Wafer processing method

Abstract

 The invention relates to a wafer processing method performed subsequent to cutting (1), the wafer processing method comprising:
a) a step of transporting (2);
b) a first wafer processing step comprising charging (4) the wafer receiving container (17) with a first processing fluid (21);
c) a step of removing (5) the first processing fluid (21) from the wafer receiving container (17);
d) a second wafer processing step by charging (7) the wafer receiving container (17) with a second processing fluid (22), wherein preferably the second processing fluid (22) is different from the first processing fluid (21);
wherein the wafer block (16) is accommodated in the wafer receiving container (17) during the steps a) to d) without removing it from the wafer receiving container (17) between those steps.

Description

[0001] The invention refers to a wafer processing method according to the preamble of claim 1. The invention also refers to a wafer receiving container.

[0002] Wafers e.g. for use in solar cells are cut from a block (also called brick or ingot) in a wire cutting device employing a metal wire and abrasives. Usually abrasives suspended in a slurry, that are transported by a metal wire, are used. Nowadays, wafers are cut more and more using fixed abrasives, which are directly attached to the metal wire. Such wire is e.g. called a diamond wire. The present invention is not restricted to one of these cutting technologies.

[0003] The ingot to be cut is of poly-crystalline or mono-crystalline semiconductor material, e.g. silicon or other materials such as sapphire, boron or rare earth metals. In the case of sapphire, the ingot is generally referred to as core or boule. The ingot is what is casted or pulled. In the case of a poly-crystalline material, usually a large ingot is casted and bricks are cut from that. In case of a mono-crystalline material normally a round ingot is made by "pulling" and cut into the typical mono-crystalline wafer shape called pseudo square. Ingot as used in this application means both the ingot as casted, the brick that is made from the ingot, the core and the boule to be cut. Moreover, the ingot (in this application the term 'ingot' also comprises boule) as used in this application means the material to be cut.

[0004] From prior art containers are known for receiving a ingot already cut into a plurality of individual wafers. When the wafers are still basically in the position they were in before they were cut, the wafers are called a wafer block or wafer brick. The containers are used to clean or otherwise treat the wafers.

[0005] Prior art is further known, where the block to be cut is attached to a beam, e.g. a glass plate, which in turn is attached to a fixture attachment. The fixture attachment may for example be horizontally inserted between two guide rails (then usually L-shaped). The guide rails are part of the cutting device and only used for inserting the workpiece into the machine. As soon as the workpiece is in position, clamps hold the fixture attachment during cutting. When the cutting process is finished, the wafer block (arrangement of a plurality of more or less parallel wafers) is slid out of the cutting device, while the fixture attachment is supported by the two guide rails.

[0006] Due to the fact, that the load is pretty heavy, the relative motion of the guide rails, the fixture attachment and the dirt (slurry) in between produces friction that is irregular and pretty hard to overcome. Moreover, when moving the block into and out of the cutting device or during transportation, the block wobbles (e.g. slip-stick effect). In the case of the inward movement this does not constitute a problem, since the ingot has not been cut yet. However, when removing said wafer block comprising a plurality of extremely thin wafers, the so called slip-stick effect causes damages to the wafers. The individual wafers tilt easily about the axis formed by the thin attachment zone on the beam or the fixture attachment, respectively. This causes adjacent wafers to touch each other. When the wafers however touch each other they may be damaged and wafers may even fall off the beam. Hence the slip-stick effect causes yield loss, resulting in higher costs per wafer.

[0007] Wafer carriers for wafers for solar cells are known from the state of the art. They often have (movable) means for holding the wafers, e.g. CN201788957U, DE102005028112A, DE102006052908A, DE102008060012 A1, DE102008060014 A1, DE102008062123 A1, DE102008060012 A1, JP10181880 A and WO2008106913 A2.

[0008] JPH05220731A discloses a wafer cutting and separating method, wherein the cutting wire of a wire saw cuts in a horizontal manner when it has reached the beam. The separated wafers are received by a wafer receiving box.

[0009] JPH07153724A discloses that the wafers cut from an ingot are received by a cassette after the step of cutting. The distance between the wire guide rollers of the corresponding wire saw is very large such that the cutting quality is adversely effected.

[0010] PCT/EP2011/064621 discloses a loading device which is used to move the work piece holder with attached brick and wafer brick in and out of the wire saw, respectively.

[0011] Following parameters are a measure for the quality of the wafers:

• Thickness, TTV (Total Thickness Variation = difference of the maximum thickness value and the minimum thickness value of silicon wafers)
• Saw marks (saw marks = grooves on the wafer surfaces, which are generated during the sawing process by a wire saw)
• Sori, Bow (sori = waviness of the wafer surface, bow = difference of the highest point of one wafer surface to the lowest one of the same wafer surface).

[0012] Also know from prior art is to do the de-gluing in the wire saw and take out the wafers from between the wire guide rollers, e.g. JP7153724 A.

[0013] Other prior art documents relate to the wafer cutting process, wherein the wafers or the cut material is immersed in fluid during the cutting step, e.g. US2012085333A1, CH696389A5, DE10157433 A1. From EP1437209 B1 it is known to partially immerse the wafers in a thick fluid or gel.

[0014] Further documents EP2110216A1, JP5220731A and US7284548B2 refer to the cutting process as such.

[0015] EP2711978A1 discloses a method of making wafers from an ingot and is particularly concerned with the handling of the wafer block after sawing and before separation of the wafers from the wafer block. The wafers are received by a wafer receiving box during or subsequent to the step of cutting the ingot into a plurality of wafers. The wafers are transported by means of the wafer receiving box to at least one wafer processing station which is arranged outside of the wire saw, wherein a wafer processing step (e.g. cleaning or de-gluing) is performed in said wafer processing station. During the step of transporting the wafers to said wafer processing station the wafer receiving box is filled with fluid, such that the wafers are immersed in said fluid. Wafer processing steps are limited to the fluid in which the wafers are immersed during transport. However, wafer handling in individual processing stations and even temporarily removing wafers from the wafer receiving box within a processing station is not only a time-consuming procedure but yields high risk of wafer damage during handling (collisions)/removing.

[0016] US 4856544 A1 discloses a stationary processing system comprising a treatment fluid supply section, a fluid input element, a pair of wafer vessels, and a treatment fluid outlet section. The supply section permits introduction of treatment fluids to the wafer vessels. The supply section is connectable to reservoirs of fluid. The fluid reservoirs can include a reservoir of hot sulfuric acid, a reservoir of pressurized nitrogen, a reservoir of an etchant, e.g., hydrofluoric acid, and a reservoir of ultrapure water and correspondingly associated valves.

[0017] WO 2011/054510 A2 discloses a method to immerse the wafers (which are still attached to the beam) subsequently in different processing baths, namely a clamping bath, de-gluing bath, rinsing bath, extraction bath. Such an arrangement is very costly and space-wasting, since multiple baths are needed as well as a complicated handling mechanism for moving the wafer block from one bath to another and to lower the wafer block into the baths.

[0018] EP 1925577 A1 discloses a method of handling wafers with a so called process boat (Prozessboot) and relates to a method of forming stacks of wafers to be doped one-sided, in particular solar wafers, for loading the process boat with batches of wafers, where a predetermined even number of wafers is serially provided in reception slots of a transfer carrier to be clamped in a horizontal plane with an upward facing stacking opening. The wafers are brought by means of the process boat into and out from a diffusion oven.

[0019] US 8,136,538 B2 discloses a stationary processing system comprising processing units. A wafer transfer part is provided with a transfer apparatus that conveys a wafer between a carrier placed on a stage and a processing part. A wafer is loaded and unloaded through one side surface of the carrier. The risk of damage is very high, since the wafer conveyed by the transfer apparatus are objected to any kind of mechanical obstacle. A processing unit has a processing vessel that can accommodate a wafer. An ozone gas and a vapor as process fluids can be supplied to the processing vessel from an ozone-gas generating part and a vapor generating part located in a process-gas generating unit.

[0020] According to other prior art, the wafer block is removed from the wire saw and placed in a wafer carrier. The wafer carrier is transported to the next stages in the process. Normally this process consists of the following steps: Sawing, pre-cleaning, de-gluing, wafer separation, final wafer cleaning, a manufacturing step such as solar cell manufacturing.

[0021] During the wafer pre-cleaning and de-gluing processes coarse dirt is removed from the wafers and the wafers are detached from the beam, respectively. After pre-cleaning and de-gluing, the wafers are normally stacked (horizontally or vertically) or held in a wafer receiving box more or less in the same configuration as they left the wire saw. In a wafer separation (=singulation) step, the wafers are separated from each other for further individual treatment. The now singulated wafers are cleaned to a degree that they can be processed chemically to be turned into e.g. a solar cell.

[0022] The problem that arises in prior art systems is that the wafers which are covered by slurry or cutting fluid and dirt begin to dry up after the cutting step. This has the adverse effect that slurry, dirt, particles, swarf, etc. sticks on and even bond (chemically react) with the wafer surfaces, that neighbouring wafers stick together or may directly collide with each other if there is for example an accelerating force exerted on the wafers during movement. This may damage the wafers during transport and/or during separation. Wafer quality thus decreases and so does the efficiency of solar cells.

[0023] Further problems arising in prior art systems relate to the complicated handling of wafers and/or process fluids. A lot of intermediate (handling and moving) steps are necessary, in order to subject the wafers of the wafer block to different processing procedures before separating them from the wafer block.

[0024] The object of the present invention is to overcome these problems and to provide a wafer processing method, wherein the wafers of the wafer block are protected all the time from the cutting process to the separation process. Time and costs for performing such a method should be reduced. In an embodiment a fully automated wafer processing method should be provided and high quality wafers be obtained. In preferred embodiments various options for the layout of the fabrication design of the wafer processing system should be possible (i.e. not restricted to a special design) and it should be possible to change the layout readily. Moreover, since the wafer blocks can be transported in the container freely and over longer distances also the logistics of a manufacturing plant should be freely designable and adaptable according to changing requirements.

[0025] Further treatment should be facilitated by keeping the wafers as clean as possible and away from reactive components, such as air (oxygen). The transport of the wafers from the wire saw to other processing stations should be performed gently, without the risk of damaging the wafers. The handling of the wafers as well as the processing steps should be uncomplicated and cost-effective.

[0026] This object is achieved by a wafer processing method performed subsequent to cutting an ingot, brick or core into a plurality of wafers in a wire saw thereby forming a wafer block and preferably prior to separating the wafers from the wafer block in a wafer separating station, the wafer processing method comprising:

a) a step of transporting the wafer block by means of a mobile wafer receiving container to at least one or within a wafer processing station which is arranged outside of the wire saw;

b) a first wafer processing step comprising charging the wafer receiving container with a first processing fluid such that the wafers become at least partially immersed in the first processing fluid;

c) a step of removing the first processing fluid from the wafer receiving container;

d) a second wafer processing step comprising charging the wafer receiving container with a second processing fluid such that the wafers become at least partially immersed in the second processing fluid, wherein preferably the second processing fluid is different from the first processing fluid;

wherein the wafer block is accommodated in the (same) wafer receiving container during the steps a) to d) without removing it from the wafer receiving container between that steps. "During steps a) to d)" means also including step a) and step d), i.e. also during step a) and during step d).

Steps a) to d), particularly steps c) and d) may be repeated.

[0027] The wafer block is not only accommodated all the time between wafer cutting and wafer separation in the same wafer receiving container (a protection implying no adverse mechanical impacts on the wafers), but is almost always wetted by fluid. The invention solves the need for different processing steps by means of bringing the (preferably different) processing fluids to the wafers within the wafer receiving container. The same mobile wafer receiving container used for accommodation and transport of the wafers (from the wire saw to the separation station) is at the same time used for subsequently receiving different processing fluids. The method also comprises the removal of a (first) processing fluid before another processing step is started by charging the wafer receiving container with a another (second) processing fluid, wherein the processing fluids are preferably different from each other. Thus, the same container is not only used for transport but also for receiving and accommodating different processing fluids and thus for different treatments of the wafers.

[0028] Preferably, the wafers of the wafer block are held by a holding device (also when still attached to the beam), the holding device being located in the wafer receiving container and being preferably detachable from the container.

[0029] Preferably, the wafer block is accommodated in the wafer receiving container with the beam (still attached after cutting the wafers in a wire saw) facing downwardly, i.e. to the bottom of the container. The wafer block including the beam may be rotated about essentially 180° during or after being removed from the wire saw. Preferably, the wafer block with the beam is held in this orientation until separating the wafers. Here, it is not necessary that the beam is removed prior to separating individual wafers from the wafer block.

[0030] After the wafers have been removed from the container, component parts comprised in the container, such as a holding device for the wafers or wafer blocks, may be treated in the same way: they stay inside the container (preventing contamination of the surroundings and the component parts themselves) and can thus be transported, while being chemically and mechanically protected, to a cleaning station and/or back to the wire saw for collecting a new load.

[0031] Preferably, the wafers are held in the wafer receiving container by a holding device preferably during all of the steps a) to d), wherein the holding device is detachably arranged in the wafer receiving container and wherein preferably the holding device comprises holding members laterally engaging the wafer block from opposite sides, and wherein subsequent to separating the wafers from the wafer block and removing them from the wafer receiving container in a separation station a cleaning step is performed for cleaning the holding device, wherein the holding device stays accommodated in the wafer receiving container during that cleaning step, said cleaning step comprises charging the wafer receiving container with a cleaning fluid such that the holding device becomes at least partially immersed in said cleaning fluid. This embodiment allows to perform all processing in the protected area of the container. The container may be prepared for receiving and processing the next wafer block without the need of removing the holding device from the container for cleaning purposes.

[0032] Preferably, said cleaning step is performed in a separate cleaning station to which the wafer receiving container is transported from the separation station.

[0033] It is explicitly mentioned that the method steps a), b), c) and d) may be performed in any order. It is preferred that at least the steps b), c) and d) are performed one after another or at least in the order as given above. Also in this preferred case it would be possible to perform additional (intermediate) steps between these steps b), c) and d). Especially steps b), c) and d) may be repeated multiple times (after step d) again starting from step b).

[0034] Step a) - i.e. step of transporting - may be performed at any time during the wafer processing method, i.e. before, during and/or subsequent to any of the steps b), c) and d). During the step of transporting the wafer receiving container may be transported from a wire saw to a processing station, which may be e.g. the separating station or any other processing station or from a processing station to another processing station. Preferably, step a) is performed before or between the steps b), c) and d).

[0035] It is also mentioned that the first processing step and the second processing step may belong to the same kind of process. The process may be e.g. a cleaning process comprising at least two processing steps. Each processing step comprise charging the wafer receiving container with a cleaning fluid: during the first processing step a large amount of dirt is removed from the wafers; during the second processing final cleaning is achieved by means of a second cleaning removing residuals of dirt from the wafers. In this case the same fluids may be used for the first and second processing step.

[0036] However, it would be also possible that a (pre-)cleaning process has already been performed within the wire saw and the process covered by the invention is a de-gluing process, which comprises at least two processing steps (the first and second processing step).

[0037] In a further embodiment the first processing step and the second processing step may belong to different processes. The first processing step may for example belong to a cleaning process and the second process may belong to a de-gluing process.

[0038] It is possible that processes are more and more integrated into single machines or processing stations. More than one process may be done within one machine or station. However, also only one process may be carried out in one processing station (e.g. pre-cleaning is done in wire saw; de-gluing is done in the container - by removing transporting fluid and introducing cleaning fluid - and the wafers are separated afterwards).

[0039] It is also possible that all processes take place in the separating station.

[0040] The processing stations may in fact be units of or locations in a single piece of equipment.

[0041] The invention is related to any kind of wafers, particularly (but not restricted to) wafers for solar cells, electronic or optical (e.g. cover glasses) applications, LEDs, etc., including any kind of semiconductor material.

[0042] The inventive solution combines in an elegant way the handling of wafers (transport after wafer cutting and before separation) and the handling of different processing fluids with the same wafer receiving container, i.e. for processing a certain wafer block only one container is needed. According to the invention it is not necessary to remove the wafer block from the container in order to apply a different processing fluid. It would be also possible that the wafer receiving container is adapted for receiving more than one wafer block and accommodates more than one wafer block during the inventive method.

[0043] An advantage of the invention over prior art is that during charging and removing fluid into/from the container, particularly charging the fluid from above the wafers and letting fluid leaving the container from below or through a duct with an opening near the bottom of the container, the wafers are (mainly) pulled away from the beam/holding means. Such a process does not adversely influence the integrity of the wafers and their relative position. In contrast to prior art, where the wafers are (several times) inserted into a fluid, the fluid will press the wafers towards the beam/holding means, making them bend and touch each other.

[0044] When the wafers are still essentially in the same position as they were immediately after finishing the cutting process, the wafer arrangement is also called a wafer block (or wafer brick). The individual wafers of the wafer block are still attached to the sacrificial substrate (or beam) of the cutting procedure. During the de-gluing process the wafer block is then detached from the sacrificial substrate. It is mentioned that in the present specification the term 'wafer block' and 'wafer' is also used for cases, in which the ingot, brick or core is not completely cut through. It would be possible to cut only the major amount, e.g. at least 95%, of a complete cut through, such that the individual wafers are still connected with each other by a thin bridge. The wafers may be separated later by carefully breaking or cutting off (e.g. with a laser).

[0045] The inventive solution provides a method for treating wafers after they have been sawn from an ingot, brick or core and up to they are separated. The invention has following advantages: mechanically and chemically protecting the wafers at all time (by accommodation in a container and immersing in a fluid), allowing various options for the layout of the fabrication as desired (long distances between wire saw, processing station(s) and separation station do not constitute a problem), allowing parallel-processing in time, reduction of costs by fully utilizing the existing machinery and the possibility of a complete full-automation process.

[0046] The wafer processing station(s) may be selected from the group consisting of a pre-cleaning station, a cleaning station, an etching station, a de-gluing station and a wafer separating station.

[0047] It is also possible that the wafer processing steps are performed in only one processing station (e.g. in a station which is at the same time the separation station) or in several subsequent processing stations.

[0048] Preferably, the method comprises: e) a step of transporting the wafer block by means of the wafer receiving container from a processing station to the separating station (in this embodiment the wafer separating station is different from the at least one foregoing wafer processing station), wherein the wafer block is accommodated in the wafer receiving container during the steps a) to e) without removing it from the wafer receiving container between that steps.

[0049] The wafer processing method according to the invention allows access to both sides of each wafer, since the wafers within the wafer block are distanced from each other by the cutting gap. Preferably, the wafer block is held within the container by a holding device, preferably laterally from opposite sides. The holding device may comprise a clamping mechanism. Two movable holding members of the clamping mechanism laterally engage the wafers (preferably immediately after the cut is finished). The wafers are clamped by the clamping mechanism during the step of transporting and during the processing steps. Thus, also after the de-gluing process (separating the wafer block from the beam) the gaps originating from wafer cutting are maintained due to the holding device, holding the wafers in their original relative position. The invention allows an efficient de-gluing procedure, since removing glue is easier and faster when de-gluing fluid may enter from both wafer sides (through the gaps). The same holds for cleaning fluid cleaning the wafers and removing residues of cutting fluid carrying sawing dust.

[0050] It is preferred that the first processing fluid and the second processing fluid are both liquids. It is also preferred that the further processing fluid - if provided - is a liquid. A liquid guarantees best protection of the wafers within the container, particularly during the step of transporting, and allows efficient interaction with the wafers or with the dirt covering the wafers or with the glue holding the wafer block to the sacrificial substrate (beam).

[0051] An aspect of the invention is that the container is moved from one processing station to the next, wherein the processing stations are distanced from each other. It is preferred that multiple containers are provided each holding a wafer block so that the processes can be carried out in time parallel.

[0052] Moreover, in the inventive method and container, the wafers are put into the container once and undergo in that (same) container all treatment steps needed up to the point where they are separated. In this way the wafers cannot collide with anything (mechanical protection) and cannot dry out since the container can be refilled quickly with the same or with a different processing fluid or with a (intermediate) protective fluid after a processing fluid has been removed (chemical protection). Different processing fluids may be filled into and removed from the container.

[0053] Preferably, during step a) - i.e. during the step of transporting the wafer block by means of a mobile wafer receiving container to at least one wafer processing station which is arranged outside of the wire saw - the wafer receiving container is at least partially filled with a fluid, preferably a cutting fluid (which may have been used during wafer cutting), such that the wafers are immersed in the fluid, and wherein preferably the fluid is removed from the wafer receiving container prior to step b) - i.e. prior to the first wafer processing step comprising charging the wafer receiving container with a first processing fluid such that the wafers become at least partially immersed in the first processing fluid. This may be done in an additional step. The term 'filled' means, that the container contains fluid during the transport, submerging the wafers at least partially.

[0054] Due to the fact that the wafers are immersed in the fluid during their transport, particularly from the wire saw to the processing station, they will not dry up and the adverse effects of sticking are overcome. They are also protected from oxygen. The fluid film between the wafers prevents that slurry, dirt, swarf, etc. sticks to the wafer surfaces and/or that the wafers stick together. Further, the fluid acts as an damper which attenuates vibrations, mechanical impacts and acceleration forces during the handling and/or transport. The wafer receiving container by means of which the transport to the processing station is performed has a transport function and may be also denoted as transport wafer receiving container. Preferably, the wafers are completely immersed in fluid during the step of transporting.

[0055] If the wafers are not directly received by the wafer receiving container during the cutting step, the wafers may be received by the wafer receiving container immediately subsequent to the cutting step, such that the wafers are kept wet and have no time to dry so. This also prevents that the particles in the fluid/components of the cutting fluid itself do not attach themselves to the wafers.

[0056] If the wafers are not (completely) received in the wafer receiving container during the cutting step (but at a later stage), means may be provided in the wire saw to keep them wet, e.g. fluid nozzles.

[0057] The wafers are now completely protected from adverse influences. This also means that in a preferred embodiment the wafers may be stored in the fluid of the wafer receiving container before being further processed. Preferably, the wafers are stored for more than 5 minutes, more preferably more than an hour, or even several hours or days. This allows to interrupt the manufacturing process without the risk of diminishing wafer quality.

[0058] During storage, the wafer receiving container may be hooked up to a supply of fluid, making a fluid flow within the container to at least partially clean the wafers. The advantage of not letting the wafers dry is that the silicon particles and cutting fluid/slurry do not stick to the wafers while drying up. Also the wafers do not build groups as easily. Groups are formed because of attractive forces acting between wafers. If the wafers are submerged, adhesive forces do not play an important role because they work on the wafers symmetrically. Grouping makes it harder to separate the wafers. Also the pre-cleaning is impaired: if two wafers stick together it is virtually impossible to clean their touching surfaces.

[0059] Wafers are placed in the wafer receiving container after they are removed from the wire saw subsequent to the cutting step and may be placed on a transport wagon. The wafers preferably are held using a wafer carrier when they leave the wire saw. Preferably, the transport is performed slowly in order not to spill fluid. Transport means for transporting the wafer receiving container during the step of transporting may be a carriage or wagon, a conveyor belt, a crane, a cableway, etc..

[0060] Preferably, already the (partially cut) wafers are submerged during cutting in fluid filled in the container, keeping them submerged during any of de-gluing, pre-cleaning, transporting to the next processing station or any combination thereof.

[0061] A further preferred goal is to be able to place the container in the separation station so that the wafers do not leave the container and thus the fluid before they are separated and/or (subsequently) cleaned completely.

[0062] The wafers are at least partially held inside the container. The wafers being held in the container by holding means.

[0063] Preferably, the wafer processing method further comprises:

• at least one further step f) of removing a wafer processing fluid from the wafer receiving container; and
• at least one further wafer processing step g) comprising charging the receiving container with a further wafer processing fluid such that the wafers become at least partially immersed in the further processing fluid, wherein the further processing fluid is preferably different from the foregoing processing fluid.

[0064] These further steps may be performed subsequent to or started during step d) (i.e. a second wafer processing step comprising charging the wafer receiving container with a second processing fluid such that the wafers become at least partially immersed in the second processing fluid, wherein the second processing fluid is preferably different from the first processing fluid).

[0065] Preferably, step b) and/or step d) and/or step g) is/are part of a process of de-gluing the wafers from a beam.

[0066] Preferably, step d), preferably also step c), is/are performed in the wafer separation station. This allows to combine individual processing procedures in a single station thereby reducing processing time and costs. Here, the de-gluing process is performed in the wafer separation station. This allows to save time, since the wafers can be taken out individually from the container immediately after the beam has been separated from the wafer block. This is done by a handling mechanism (separator head) taking each wafer individually.

[0067] Preferably, the first processing step is part of a de-gluing process and any of the subsequent steps is part of a cleaning process.

[0068] The wafer separating station may also be at a large distance from the wire saw. However, it takes only one separator head to serve about eight wire saws. Meaning that the distance between the separating station and wire saw can be also kept small. If a factory wants to keep chemicals at one location, the distance from wire saw to the separating station may become large. This is not a problem with the inventive solution, since the wafers are well protected (mechanically and chemically) all the time and can thus be transported easily.

[0069] Preferably, during step e) - i.e. a step of transporting the wafer block by means of the wafer receiving container to the separation station - the wafer receiving container is at least partially filled with a fluid, such that the wafers are immersed in the fluid. This allows to achieve the advantageous effects described above with respect to step a) - wafers do not dry up.

[0070] Preferably, at least one step of cleaning the wafer receiving container is performed between a step of removing a wafer processing fluid from the wafer receiving container and a step of charging the wafer receiving container with a different processing fluid, wherein the wafer block is kept accommodated in the wafer receiving container during the step of cleaning the wafer receiving container (i.e. the wafer block is kept accommodated in the wafer receiving container between the step of removing a wafer processing fluid from the container and the step of charging the container with a wafer processing fluid). This allows to remove residues of a foregoing processing fluid as well as dirt, particles, swarf, etc.. This embodiment thus provides means for cleaning the container between two different treatments to prevent contamination.

[0071] Preferably, at least one step of removing a wafer processing fluid from the wafer receiving container and at least one step of charging the wafer receiving container with a wafer processing fluid at least partially overlaps in time. In this case the supply (of e.g. the new processing fluid) and the removal (of the foregoing processing fluid) is spatially separated. This allows to optimize the process in time and guarantees that the wafers do not dry during the exchange of the processing fluids.

[0072] Alternatively, particularly if the different fluids must not mix with each other, a (first) fluid is completely removed from the container before another (second) fluid is charged into the container. Here, the container becomes temporarily empty between processing steps.

[0073] Preferably, removing a wafer processing fluid from the wafer receiving container is performed via an outlet in the lower portion of the wafer receiving container and charging the wafer receiving container with a wafer processing fluid is performed via an inlet arranged in the upper portion of the wafer receiving container. In such a way supply and removal of fluids is spatially separated.

[0074] Preferably, the wafer receiving container has at least one opening preferably in its top portion, more preferred in a lid and wherein a fluid supply duct for charging the container with a processing fluid and/or a removing duct for removing processing fluid from the container is/are inserted in the at least one opening.

[0075] Preferably - in the case of a removing duct is inserted - the removing duct extends to the bottom region of the wafer receiving container.

[0076] Preferably, the wafer receiving container has at least two openings preferably in its top portion, more preferred in a lid and wherein a fluid supply duct for charging the container with a processing fluid is inserted in one of the openings and a removing duct for removing processing fluid from the container is inserted in the other opening, wherein preferably the removing duct extends to the bottom region of the wafer receiving container (i.e. the opening of the duct may be located near the bottom of the container). In such a way supply and removal of fluids is spatially separated. The ducts are not part of the wafer receiving container. They belong to a wafer processing station and are inserted if fluid has to be handled. The ducts may be inserted at the same time, in order to reduce process steps.

[0077] Preferably, the wafer receiving container comprises at least two inlets, preferably in an upper portion, more preferably in a lid of the wafer receiving container, wherein the step of charging a first wafer processing fluid to the wafer receiving container is performed via a first inlet and the step of charging a second wafer processing fluid which is different from the first processing fluid is performed via the second inlet. This allows to provide different inlets for different processing fluids. It is not necessary to clean an inlet from a first fluid prior to charging the container with a second fluid, since there is a separate inlet for that second fluid. A partial mixing of different fluids is also avoided.

[0078] Preferably, the wafer receiving container accommodating the wafer block is moved between wafer processing steps from one processing station to another processing station or from one subunit to another subunit of the same processing station. This allows to move the container from one 'docking station' to another. A docking station may comprise a connection to at least one fluid reservoir for charging the container and/or a connection to at least one fluid tank for receiving used fluid from the container. The connection(s) is/are connected to the inlet(s) and/or outlet(s) of the container to perform the charging and removing steps.

[0079] Preferably, the first processing fluid and/or the second processing fluid and/or, if provided, the at least one further processing fluid is/are selected from the group consisting of water, acid, lye, solution, etching fluid and cleaning fluid.

[0080] Preferably, the first wafer processing step and/or the second wafer processing step and/or, if provided, the at least one further wafer processing step is/are part of at least one process selected from the group consisting of pre-cleaning the wafers, cleaning the wafers, etching the wafers and de-gluing wafers from a beam used for wafer cutting. As already mentioned, the first processing step and the second processing step may belong to the same process or to different processes (e.g. cleaning and de-gluing).

[0081] A distinction can be made between: transporting steps; processing steps comprising the fluid handling; processes; and processing stations.

[0082] Different processing steps may be part of the same process or different processes. Processes are realized using the processing steps and transporting steps. A processing station is the location where the processing steps comprising the fluid handling (and maybe also transporting steps) are carried out. The fluid handling steps (charging fluid, removing fluid) of a process may take place in one or multiple processing stations. A process may take place in one or multiple stations.

[0083] Preferably, the wafers are wetted by fluid, preferably almost always immersed in fluid, during the whole wafer processing method between wafer cutting and wafer separation. Adverse effects if wafers dry up are efficiently avoided.

[0084] Preferably, during the separation step in the wafer separation station the wafer block (from which individual wafers are taken) is still accommodated in the (same) wafer receiving container in which it was accommodated during the processing steps using the different processing fluids.

[0085] The invention also relates to a wafer processing system being capable of performing a wafer processing method as described above and/or according to one of the above embodiments, the system comprising: a mobile wafer receiving container, a supply for charging the mobile wafer receiving container accommodating a wafer block with a first wafer processing fluid and a supply for charging the mobile wafer receiving container accommodating a wafer block with a second wafer processing fluid, wherein the second fluid is different from the first fluid.

[0086] Preferably, the wafer receiving container is covered by a lid during step a), preferably during all steps a) to d), preventing fluid from being spilled out of the container.

[0087] The wafer receiving container is preferably made of a metal.

[0088] The object of the invention is also achieved with a mobile wafer receiving container for receiving wafers in form of a wafer block, wherein the wafer receiving container is adapted for use with a wafer processing method according to one of the foregoing embodiments. The wafer receiving container is a mobile transport container and is capable of receiving and holding a fluid.

[0089] Preferably, the wafer receiving container comprises at least two fluid inlets for different wafer processing fluids, wherein preferably the fluid inlets are arranged in the upper portion, more preferred in a lid of the wafer receiving container.

[0090] Preferably, the wafer receiving container comprises at least two fluid outlets for different wafer processing fluids, wherein preferably the fluid outlets are arranged in the lower portion, more preferred in the bottom of the wafer receiving container.

[0091] Preferably, the wafer receiving container has at least two openings preferably in its top portion, more preferred in a lid, for inserting fluid ducts of a processing station.

[0092] Preferably, the wafer receiving container is attached to a transport means, preferably to rolls, wheels or a guide rail.

[0093] Transporting means may be provided also for multiple containers in queue. In this way containers, in which de-gluing takes place, can be queued. Also containers, in which a certain process has already finished, can thus be queued, for example for over-night processing. Since de-gluing and neutralizing is faster than separating, multiple containers may queue up in front of a separating station. They may be handled when no wire saws are running. Thus, also multiple containers may serve a (much more expensive) separator. Operational costs and capex may be saved. Preferably, the wafer receiving container is transported or moved by hand. For facilitating movement by hand the receiving container is provided with a handle (or grip).

[0094] Preferably, two different processing stations are provided, wherein the processing stations are distanced from each other. This allows to realize an optimized and economic wafer processing system.

[0095] In the following a concept of the invention is described: The container (also called: basin) with the wafers is always (i.e. during the whole processing steps between cutting and separating; preferably also during separating) accommodated in the container. The container may be (completely or partially) empty from time to time to exchange fluids.

[0096] The container is transported from the wire saw to

• consecutive processing stations; or
• only to one processing station, wherein preferably the container being movable inside that station between different processing units or different processes being carried out in that station in one and the same location.

[0097] The transport container is subsequently filled with different fluids for different processes. The wafer processing method comprises: cleaning wafers. The wafers do not leave the container until a first and a second (i.e. different) process with different fluids filing the container have been performed.

[0098] A typical process is described herein: Wafers (still) attached to the sacrificial substrate (or beam) of the wafer cutting procedure is placed in the container. (Hot) water or (hot) acetic acid is introduced into the container until the wafers have detached themselves from the sacrificial substrate.

[0099] If acid is used: the container is cleaned using water in an intermediate step. The container may be filed multiple times (with different fluids). The wafers are separated while the wafers are in a clean water. This may be e.g. done by a separation head as disclosed in DE102006011870A1, the disclosure of which is taken into this description by reference.

[0100] In the following preferred processing steps are described:

Neutralization step: After treatment with an acid or lye, the wafers may be neutralized using e.g. water or a solution.

[0101] Wafer cleaning process: Cleaning of the wafers could also be done with warmed water (e.g. at least 60°C, preferably at least 80°C warmer than room temperature). In addition the cleaning process can be stimulated using ultra sound, bubbles, (varying) under-pressure. The cleaning process is performed before and/or after the de-gluing process

[0102] Repetition of steps: A fluid (e.g. (DI-) water for neutralization) may be introduced and removed from container multiple times to get the desired result.

[0103] Processing times: First and second wafer processing steps may have different processing times. This allows work to be done in advance and later process further.

[0104] De-gluing process: The de-gluing process is preferably performed by letting the wafer block accommodated in the container filled with (warm) water or acetic acid (and or other acids). The water may be heated inside the container and a flow may be sustained.

[0105] During any processing step a flow of fluid may be generated in the container

[0106] The container may have a lid forming a (removable) cover of the container. Alternatively a lid may be part of a processing station (preferably for temporarily covering the container). I.e. the lid may belong to the wafer receiving container or to the processing station. In any case the lid is provided for covering the container and thus the fluid therein. Preferably the lid has integrated inlets, ducts and/or openings.

[0107] The container may have at least one duct extending to the bottom of the container to be connected to a supply for a processing fluid. The container may have heating means and/or means for generating a flow. All may enter basing through opening in lid or be part of lid. Ducts or nozzles may also be used to generate and maintain a flow. Preferably, a duct forming a means for filing and/or emptying the bath(s) extends into the container all the way from the top to the bottom of the container.

[0108] Alternatively, the container may be open on its top side (i.e. without a lid).

[0109] Under-pressure: Means for creating under-pressure can be provided so that the processes can be conducted under reduced pressure. Also means for generating ultra sound or bubbles may be provided.

[0110] A lid for (temporarily) covering the container may also be part of a processing station. Alternatively, the lid may be movably attached to the container.

[0111] Flushing: The container may be filled or charged (e.g. with a sprinkler) from above and drained at the same time from below. In this way the fluid can be replaced without the wafers getting dry. The draining or removing may be done faster than the sprinkling, so that the wafers are cleaned without mixing too much of both wafer processing fluids (producing waste). A sprinkler may also be used to keep the wafers wet, the fluid being removed from the container continuously.

[0112] Preferably, during the step of cutting the wafers, the wafer receiving container is removably held or removably attached in the wire saw such that the wafers are received by the wafer receiving container during the step of cutting. This allows a simple uncomplicated handling, because the wafers are protected by the wafer receiving box and the fluid inside immediately after their cut. It is not necessary to retrieve the wafers through the wire web. They are directly accommodated in the receiving box, which is removable from the wire saw. The transport to further processing stations is performed by means of that wafer receiving container. Normally, the container is placed and secured in the wire saw prior to cutting. As soon as the wafers need to be removed from the wire saw, the container is disengaged and taken from the wire saw. Removably as used here means that the container is temporary (during cutting) part of the wire saw and easily removed by the operator as part of normal daily routine. Means may be provided for easily attaching and detaching the wafer container by hand or (semi-) automatically.

[0113] Preferably, during the step of cutting the wafers, the wafer receiving container is at least partially filled with a fluid such that the wafers are immersed in said fluid during the step of cutting. The fluid protects the wafers already during the step of cutting. This fluid may be a cutting fluid, another fluid than used for cutting or unused (and thus clean) cutting fluid that may later be used for cutting.

[0114] Preferably, during and/or subsequent to the step of cutting, a fluid flow is generated in said fluid of the wafer receiving container, preferably when the wafer receiving container is still inserted in the wire saw and/or during storage of the wafers in the wafer receiving container prior to a wafer processing step. This allows a pre-cleaning process during which particles generated during the cutting process can be removed from the wafers. During the cutting process the fluid may also act a cooling medium.

[0115] Preferably, the wafer receiving container comprises a clamping mechanism and wherein the wafers are clamped by the clamping mechanism during the transport and during the processing steps. The clamping of the wafers protects them from striking to each other, rocking movement/flow in the fluid and/or vibrations.

[0116] Further embodiments of the invention are indicated in the figures and in the dependent claims. The list of reference marks forms part of the disclosure. The invention will now be explained in detail by the drawings. In the drawings:

Fig. 1 shows a wire saw for cutting a plurality of wafers from an ingot,

Fig. 2 shows the path of a wafer receiving container from a wire saw to a wafer separating station via wafer processing stations,

Fig. 3 shows an embodiment of wafer processing stations,

Fig. 4 an embodiment of the wafer processing method comprising a sequence of method steps,

Fig. 5 shows an embodiment of a wafer receiving container,

Fig. 6 shows an embodiments of a wafer separating station,

Fig. 7 shows an embodiment of a wafer receiving container with fluid ducts inserted.

[0117] Fig. 1 shows a wire saw 13 for cutting a plurality of wafers from an ingot 14 (also called brick or core). The wire saw 13 comprises a support base for positioning ingot 14 with respect to a wire web which is formed by a cutting wire. Ingot 14 is glued to a beam 27 (also called sacrificial substrate), which in turn is attached to a fixture attachment usually made of metal. The beam 27 is mounted to the fixture attachment which in turn is detachably mounted to the support base of the wire saw 13. Wire saw 13 further comprises wire guide rollers for forming a field of cutting wire, i.e. wire web. During the cutting process, the ingot 14 is pushed through the wire web, causing the cutting wire to bend downwards (not shown). Because of this bow of the cutting wire and the different cutting speed of the individual wire segments, the top edges of the ingot are cut before the middle part of the ingot is completely cut. It is the purpose of the sacrificial substrate or beam 27 to keep the fixture attachment at a distance of the ingot 14, so that the fixture attachment is not cut. The beam 27 - which is relatively inexpensive - is replaced after each cut.

[0118] After the cuts have been made (all wafers are cut in parallel), the wafers 15 (Fig. 2) are still attached to the beam 27 giving the wafer block a comb-like structure.

[0119] Fig. 2 shows some aspects of the wafer processing method performed between cutting 1 an ingot 14 into a plurality of wafers 15 in a wire saw 13 thereby forming a wafer block 16 and separating 11 the wafers 15 from the wafer block 16 in a wafer separating station 12. The wafer processing method comprises:

a) a step of transporting 2 the wafer block 16 by means of a mobile wafer receiving container 17 to at least one wafer processing station 12, 18, 19 which is arranged outside of the wire saw 13;

b) a first wafer processing step comprising charging 4 the wafer receiving container 17 with a first processing fluid 21 such that the wafers 15 become at least partially immersed in the first processing fluid 21 (left part of Fig. 3);

c) a step of removing 5 the first processing fluid 21 from the wafer receiving container 17 (right part of Fig. 3);

d) a second wafer processing step comprising charging 7 the wafer receiving container 17 with a second processing fluid 22 such that the wafers 15 become at least partially immersed in the second processing fluid 22, wherein the second processing fluid 22 is different from the first processing fluid 21 (right part of Fig. 3);

[0120] The wafer block 16 is accommodated in the (same) wafer receiving container 17 during the steps a) to d) without removing it from the wafer receiving container 17 between that steps.

[0121] In the embodiment of Fig. 2 the method also comprises: e) a step of transporting 10 the wafer block 16 by means of the wafer receiving container 17 from a processing station 19 to the separating station 12. The wafer block 16 is accommodated in the wafer receiving container 17 during the steps a) to e) without removing it from the wafer receiving container 17 between that steps. During transporting 10 the wafer block 16 the wafer receiving container 17 is at least partially filled with a fluid, such that the wafers are immersed in the fluid.

[0122] As can be seen from Fig. 2 and 3 during step a) - step of transporting 2 - the wafer receiving container 17 is at least partially filled with a fluid 20, preferably a cutting fluid (which may have been used during wafer cutting 1), such that the wafers 15 are immersed in the fluid 20. The fluid 20 is removed 3 from the wafer receiving container 17 prior to step b) or at least partially overlapping in time with step b) - i.e. charging 4 (left part of Fig. 3).

[0123] The wafer processing method between step d) and step e) and/or between step c) and step d) further comprise (Fig. 4):

• a step of removing 8 the processing fluid 21, 22 from the wafer receiving container 17; and
• at least one further wafer processing step comprising charging 9 the receiving container 17 with a further processing fluid 23 such that the wafers 15 become at least partially immersed in the further processing fluid 23, wherein the further processing fluid 23 is different from the second processing fluid 22.

[0124] Preferably, step d) is part of a process of de-gluing the wafers from a beam 27 and wherein step d), preferably also step c), is/are performed in the separation station 12.

[0125] The embodiment of the container 17 as shown in figure 2 has two openings 24a and 24b used for introducing ducts (not shown) into the container for respectively introducing into and/or removing a fluid from container 17. Preferably the latter duct may extend to the bottom of the container so that the fluid can be removed from below the wafers (by sucking the fluid upwards, e.g. by a pump).

[0126] Fig. 4 schematically shows a sequence of possible method steps, however it is mentioned, that it is not necessary to perform all of them. As indicated in the embodiment of Fig. 4 at least one step of cleaning 6 the wafer receiving container 17 is performed between a step of removing a fluid 21 from the wafer receiving container 17 and a step of charging the wafer receiving container 17 with a different processing fluid 22. Here, priority is given to the cleaning of the wafer receiving container 17. During this step the wafer block 16 is kept accommodated in the wafer receiving container 17.

[0127] It is possible, that a step of removing a wafer processing fluid 21, 22 from the wafer receiving container 17 and a step of charging the wafer receiving container 17 with a different wafer processing fluid 22, 23 at least partially overlaps in time.

[0128] Fig. 3 shows that removing a wafer processing fluid 21, 22 from the wafer receiving container 17 is performed via an outlet 25a, 25b in the lower portion, preferably in the bottom, of the wafer receiving container 17 and charging the wafer receiving container 17 with a wafer processing fluid 21, 22 is performed via an inlet 24a, 24b arranged in the upper portion (here: in a lid 26) of the wafer receiving container 17.

[0129] In the embodiment of Fig. 3 the wafer receiving container 17 comprises at least two inlets 24a, 24b, wherein the step of charging a first wafer processing fluid 21 to the wafer receiving container 17 is performed via a first inlet 24a and the step of charging a second wafer processing fluid 22 which is different from the first processing fluid 21 is performed via the second inlet 24b. The same principle may be applied for the outlets 25a and 25b (Fig. 3).

[0130] The wafer receiving container 17 accommodating the wafer block 16 is moved between wafer processing steps from one processing station 18, 19 to another processing station 19, 12. It is also possible that there are more processing steps than processing stations. In this case it would be possible to move the container 17 from one subunit to another subunit of the same processing station or it may remain in the same place.

[0131] The first processing fluid 21 and/or the second processing fluid 22 and/or, if provided, the at least one further processing fluid 23 is/are selected from the group consisting of water, acid, lye, solution, etching fluid and cleaning fluid. The first wafer processing step and/or the second wafer processing step and/or, if provided, the at least one further wafer processing step is/are part of at least one process selected from the group consisting of pre-cleaning the wafers, cleaning the wafers, etching the wafers and de-gluing wafers from a beam used for wafer cutting.

[0132] The wafers 15 are wetted by fluid, preferably almost always immersed in fluid, during the whole wafer processing method between wafer cutting 1 and wafer separation 11.

[0133] Fig. 5 shows a wafer separating station 12 comprising a separator head 30. The separator head 30 comprises a conveyor (belt) engaging individually to the wafers 15 and taking them out of the container 17. In such a way the wafers 15 are singularized from the wafer block 16 and may be transported to further treatment processes.

[0134] Fig. 6 shows a mobile wafer receiving container 17 for receiving wafers 15 in form of a wafer block 16, wherein the wafer receiving container 17 is adapted for use with a wafer processing according to the invention. Container 17 may have a handle 31 for moving it by hand.

[0135] As already discussed with respect to Fig. 3, the wafer receiving container 17 may comprise at least two fluid inlets 24a for different wafer processing fluids, wherein preferably the fluid inlets 24b are arranged in the upper portion, more preferred in a lid 26 of the wafer receiving container 17.

[0136] It would be also possible, that the wafer receiving container 17 comprises at least two fluid outlets 25a, 25b for (removing) different wafer processing fluids, wherein preferably the fluid outlets 25a, 25b are arranged in the lower portion, more preferred in the bottom of the wafer receiving container 17.

[0137] As can be seen from Fig. 2, 3 and 6 the wafer receiving container 17 is attached to a transport means 29 (here in form of rolls or wheels. Guide rails would be possible as well, if the system has rails between and in the processing stations.

[0138] As can be seen from Fig. 1, the wafer receiving container 17 comprises a clamping mechanism 28. Two movable holding members laterally engage the wafers 15 when the cut is finished. The wafers 15 are clamped by the clamping mechanism 28 during the step of transporting 2, 10 and during the processing steps.

[0139] In the embodiment of Fig. 7 the wafer receiving container 17 has at least two openings in its top portion, here in a lid 26. A fluid supply duct 32a for charging the container 17 with a processing fluid is inserted in one of the openings and a removing duct 32b for removing processing fluid from the container 17 is inserted in the other opening. In the preferred embodiment the removing duct 32b extends to the bottom region of the wafer receiving container 17.

[0140] Fig. 7 also shows that the wafer block 16 with the beam 27 still attached to the wafers is oriented such, that the beam 27 faces downwards (i.e. to the bottom region of the container 17) and the wafers upwards. The inventive method may be also performed with this orientation.

[0141] The invention is not restricted to these embodiments. Other variants will be obvious for the person skilled in the art and are considered to lie within the scope of the invention as formulated in the following claims. Individual features described in above specification, particularly with respect to the figures may be combined with each other to form other embodiments and/or applied mutatis mutandis to what is described in the claims and to the rest of the description.

List of reference marks

[0142] 

1

cutting

2

transporting

3

removing

4

charging

5

removing

6

cleaning

7

charging

8

removing

9

charging

10

transporting

11

wafer separation

12

wafer separating station

13

wire saw

14

ingot

15

wafers

16

wafer block

17

wafer receiving container

18

processing station

19

processing station

20

fluid

21

first processing fluid

22

second processing fluid

23

further processing fluid

24a

first inlet

24b

second inlet

25a

first outlet

25a

second outlet

26

lid

27

beam

28

holding device

29

transport means

30

separator head

31

handle of container 17

32a

fluid supply duct

32b

fluid removing duct

Claims

1. Wafer processing method performed subsequent to cutting (1) an ingot (14), brick or core into a plurality of wafers (15) in a wire saw (13) thereby forming a wafer block (16), the wafer processing method comprising:

a) a step of transporting (2) the wafer block (16) by means of a mobile wafer receiving container (17) to at least one or within a wafer processing station (12, 18, 19) which is arranged outside of the wire saw (13);

b) a first wafer processing step comprising charging (4) the wafer receiving container (17) with a first processing fluid (21) such that the wafers (15) become at least partially immersed in the first processing fluid (21);

c) a step of removing (5) the first processing fluid (21) from the wafer receiving container (17);

d) a second wafer processing step comprising charging (7) the wafer receiving container (17) with a second processing fluid (22) such that the wafers (15) become at least partially immersed in the second processing fluid (22), wherein preferably the second processing fluid (22) is different from the first processing fluid (21);

wherein the wafer block (16) is accommodated in the wafer receiving container (17) during the steps a) to d) without removing it from the wafer receiving container (17) between those steps.

2. Wafer processing method according to claim 1, wherein the method comprises:

e) a step of transporting (10) the wafer block (16) by means of the wafer receiving container (17) from a wafer processing station (18, 19) to the separating station (12),

wherein the wafer block (16) is accommodated in the wafer receiving container (17) during the steps a) to e) without removing it from the wafer receiving container (17) between that steps.

3. Wafer processing method according to claim 1 or 2, wherein during step a) the wafer receiving container (17) is at least partially filled with a fluid (20), preferably a cutting fluid, such that the wafers are at least partially immersed in the fluid (20), and wherein preferably the fluid (20) is removed (3) from the wafer receiving container prior to step b) or at least partially overlapping in time with step b).

4. Wafer processing method according to one of the preceding claims, wherein the wafer processing method further comprises:

- at least one further step f) of removing (8) a processing fluid (21, 22) from the wafer receiving container (17); and

- at least one further wafer processing step g) comprising charging (9) the receiving container (17) with a further processing fluid (23) such that the wafers (15) become at least partially immersed in the further processing fluid (23), wherein preferably the further processing fluid (23) is different from the foregoing processing fluid (22).

5. Wafer processing method according to one of the preceding claims, wherein step b) and/or step d) and/or step g) is/are part of a process of de-gluing the wafers from a beam (27),
and/or wherein step d), preferably also step c), is/are performed in the separation station (12) for separating the wafers (15) from the wafer block (16),
and/or wherein during step e) the wafer receiving container (17) is at least partially filled with a fluid, such that the wafers are immersed in the fluid.

6. Wafer processing method according to one of the preceding claims, wherein at least one step of cleaning (6) the wafer receiving container (17) is performed between a step of removing a fluid (20, 21, 22) from the wafer receiving container (17) and a step of charging the wafer receiving container (17) with the same or a different processing fluid (21, 22, 23), wherein the wafer block (16) is kept accommodated in the wafer receiving container (17) during the step of cleaning (6) the wafer receiving container (17).

7. Wafer processing method according to one of the preceding claims, wherein removing a wafer processing fluid (21, 22, 23) from the wafer receiving container (17) is performed via an outlet (25a, 25b) in the lower portion, preferably in the bottom, of the wafer receiving container (17) and charging the wafer receiving container (17) with a wafer processing fluid (21, 22, 23) is performed via an inlet (24a, 24b) arranged in the upper portion, preferably in a lid (26), of the wafer receiving container (17),
or wherein the wafer receiving container (17) has at least one opening preferably in its top portion, more preferred in a lid (26) and wherein a fluid supply duct (32a) for charging the container (17) with a processing fluid and/or a removing duct (32b) for removing processing fluid from the container (17) is/are inserted in the at least one opening, wherein preferably the removing duct (32b) extends to the bottom region of the wafer receiving container (17).

8. Wafer processing method according to one of the preceding claims, wherein the wafer receiving container (17) comprises at least two inlets (24a, 24b), preferably in an upper portion, more preferably in a lid (26) of the wafer receiving container (17), wherein the step of charging a first wafer processing fluid to the wafer receiving container (17) is performed via a first inlet (24a) and the step of charging a second wafer processing fluid which is different from the first processing fluid is performed via the second inlet (24b).

9. Wafer processing method according to one of the preceding claims, wherein the wafer receiving container (17) accommodating the wafer block (16) is moved between wafer processing steps from one processing station (18, 19) to another processing station (19, 12) or from one subunit to another subunit of the same processing station.

10. Wafer processing method according to one of the preceding claims, wherein the first processing fluid (21) and/or the second processing fluid (22) and/or, if provided, the at least one further processing fluid (23) is/are selected from the group consisting of water, acid, lye, solution, etching fluid and cleaning fluid.

11. Wafer processing method according to one of the preceding claims, wherein the first wafer processing step and/or the second wafer processing step and/or, if provided, the at least one further wafer processing step, or any combination thereof is/are part of at least one process selected from the group consisting of pre-cleaning the wafers, cleaning the wafers, etching the wafers and de-gluing wafers from a beam used for wafer cutting.

12. Wafer processing method according to one of the preceding claims, wherein the wafers (15) are held in the wafer receiving container (17) by a holding device (28) preferably during all of the steps a) to d), wherein the holding device (28) is detachably arranged in the wafer receiving container (17) and wherein preferably the holding device (28) comprises holding members laterally engaging the wafer block (16) from opposite sides, and wherein preferably subsequent to separating the wafers (15) from the wafer block (16) and removing them from the wafer receiving container (17) in a separation station (12), a cleaning step is performed for cleaning the holding device (28), wherein the holding device (28) stays accommodated in the wafer receiving container (17) during the steps a) to d) and during that cleaning step without removing it from the wafer receiving container (17) between those steps, said cleaning step comprises charging the wafer receiving container (17) with a cleaning fluid such that the holding device (28) becomes at least partially immersed in said cleaning fluid, and wherein preferably said cleaning step is performed in a separate cleaning station to which the wafer receiving container (17) is transported from the separation station (12).

13. Wafer processing method according to one of the preceding claims, wherein the wafer receiving container (17) is covered by a lid (26) during at least one of the steps a) to d), preferably during all of the steps a) to d).

14. Mobile wafer receiving container (17) for receiving wafers (15) in form of a wafer block (16), wherein the wafer receiving container (17) is adapted for use with a wafer processing method according to one of the preceding claims, wherein preferably the wafer receiving container (17) comprises a wafer holding device (28) for holding the wafers in the container (17), preferably comprising holding members laterally engaging the wafers.

15. Wafer receiving container according to claim 14, wherein the wafer receiving container (17) comprises at least two fluid inlets (24a, 24b), preferably in form of openings or ducts extending into the wafer receiving container (17), for different wafer processing fluids, wherein preferably the fluid inlets (24b) are arranged in the upper portion, more preferred in a lid (26) of the wafer receiving container (17),
and/or wherein the wafer receiving container (17) comprises at least two fluid outlets (25a, 25b), preferably in form of ducts extending into the wafer receiving container (17), for different wafer processing fluids, wherein preferably the fluid outlets (25a, 25b) are arranged in the lower portion, more preferred in the bottom of the wafer receiving container (17).

Drawing