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(11) | EP 1 029 600 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
| published in accordance with Art. 158(3) EPC |
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| (54) | CLEANING DEVICE |
| (57) Disclosed is a cleaning apparatus having a very simple arrangement and capable of
reliably removing the reaction product and the used fluid which have built up in a
brush. A recessed section (2) having a size for permitting a brush to be located therein
is formed to a main unit (4) having an open upper surface, and a chamber section (5)
is formed so as to surround the recessed section (2). A plurality of nozzle sections
(6) are formed to the main unit (4) between the chamber section (5) and the recessed
section (2), whereas an introduction hole (7) communicating with the chamber section
(5) and a discharge hole (3) communicating with the recessed section (2) are opened
to the main unit (4), respectively. |
TECHNICAL FIELD
[0001] The present invention relates to a cleaning apparatus, and more specifically, to a cleaning apparatus for cleaning a brush which is used in a polishing apparatus for polishing a workpiece such as a semiconductor wafer, a CD disc and the like, which has a mirror-finished surface and is required to have a uniform thickness, by means of an abrasive cloth.
BACKGROUND ART
[0002] In general, the surfaces of semiconductor wafers, CD discs and the like must be mirror-finished to a uniform thickness. When this is described as to the semiconductor wafer, the semiconductor wafer, which is composed of sliced monocrystal silicon, must be polished to a uniform thickness with the surface of it precisely mirror-finished before a semiconductor circuit is formed on the wafer.
[0003] For this purpose, in a polishing apparatus, a base plate (or platen), on which an abrasive cloth such as felt is adhered, is rotated as well as a plurality of heads, on which a plurality of semiconductor wafers are fixed, are also rotated so that the abrasive cloth rotates relatively to the semiconductor wafers.
[0004] In this state, a surface of each semiconductor wafer is polished by being pressed against the abrasive cloth while supplying an alkaline solution containing abrasive grain such as fine particle silica or the like to the rotating abrasive cloth, whereby the surface of each semiconductor wafer is mirror-finished.
[0005] However, as the abrasive cloth is used, it is clogged with the slurry of a reactive product penetrated thereinto, which is composed of an abrasive and particles separated from the semiconductor wafer when the wafer is polished. The polishing capability of the abrasive cloth is dropped thereby.
[0006] A means for solving the above problem is to provide a dressing device with the polishing apparatus as proposed in Japanese Unexamined Patent Publication No. 3-10769. The dressing device is arranged such that high pressure pure water is injected to the polishing surface of the abrasive cloth from an injection nozzle while a polishing job is carried out and the reaction product, which builds up in the deep layer of the abrasive cloth, is beaten and removed by the impact of the injected water.
[0007] The dressing device is provided with a splash prevention cover for entirely surrounding the nozzle in order to prevent the reaction product, which has been removed by the injection of the high pressure pure water, from being sprung out and splashed to the surroundings by the high pressure pure water injected to the reaction product thereafter.
[0008] With this means, however, the pure water and the reaction product build up in the splash prevention cover and the surface of the abrasive cloth is covered with them, whereby the removing capability of the abrasive cloth for removing the reaction product by the splash of the high pressure pure water is dropped.
[0009] To prevent the drop of the removing capability, there has been proposed Japanese Patent No. 2622069. Japanese Patent No. 2622069 proposes a device provided with a brush, and the device is arranged such that a fluid injected to the abrasive cloth is not caused to build up at the position where the fluid is injected to the abrasive cloth but is caused to temporarily build up at a position apart from the above injecting position and discharged by the brush while the energy of the built-up fluid is lost by the brush.
[0010] However, the brush used in the device has the following problem. That is, the slurry of the reactive product, which is composed of an abrasive penetrating the abrasive cloth and particles separated from the semiconductor wafer when the wafer is polished, enters the inside of the brush. Thus, the object intended by the device cannot be achieved as a time passes, although the reaction product and the used fluid are satisfactorily discharged at the beginning of the use of the brush.
[0011] This problem arises likewise in the polish of the surface of a CD disc and in the polish of the surface of liquid crystal glass, and the like, in addition to the polish of the semiconductor wafer.
[0012] An object of the present invention is to provide a cleaning apparatus capable of always securing the initial state of a brush, which is used in a polishing apparatus for polishing a workpiece such as a semiconductor wafer, a CD disc and so forth whose surface must be mirror-finished to a uniform thickness, when the brush cannot be satisfactorily used, as a time passes, due to the reaction product and the used fluid which have built up in the inside of the brush. In the cleaning apparatus, the initial state of the brush is restored by discharging the reaction product and the used fluid which have entered the inside of the brush.
DISCLOSURE OF THE INVENTION
[0013] That is, according to the present invention, a cleaning apparatus is arranged such that a recessed section, which has an open upper surface and a size for permitting a brush to be located in the recessed section, is formed to a main unit, a chamber section is formed in the inside of the main unit so as to surround the recessed section, a plurality of nozzle sections are formed to the main unit between the chamber section and the recessed section, and an introduction hole communicating with the chamber section and a discharge hole communicating with the recessed section are opened to the lower surface of the main unit, respectively. Accordingly, the cleaning apparatus can discharge the reaction product and the used fluid, which have entered the inside of the brush. Further, the recessed section is formed to a square, and the chamber section is formed to a square surrounding the recessed section.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014]
FIG. 1 is a schematic plan view showing a preferable cleaning apparatus according to the present invention; and
FIG. 2 is a schematic longitudinal sectional view of the cleaning apparatus.
BEST MODE OF CARRYING OUT THE INVENTION
[0015] The present invention will be described below in more detail with reference to the accompanying drawings.
[0016] FIG. 1 shows a schematic plan view of a cleaning apparatus, and FIG. 2 shows a schematic sectional view of the cleaning apparatus.
[0017] The cleaning apparatus 1 of the present invention is provided with a recessed section 2 having a size in which a brush used in a polishing apparatus can be accommodated. A discharge hole 3 is formed to the bottom of the recessed section 2 at the center thereof, and the inside of the recessed section 2 communicates with the lower surface of a main unit 4 through the discharge hole 3.
[0019] A plurality of nozzle sections 6 are formed to the main unit 4 between the chamber section 5 and the recessed section 2 over the entire periphery of the recessed section 2.
[0020] Further, an introduction hole 7, which is opened to the lower surface of the main unit 4, is formed to the chamber section 5.
[0021] As the arrangement of the main unit 4, an upper surface section and a lower surface section may be separately made and formed to an integral body. In addition to the above arrangement, various arrangements may be employed. As to the material of the main unit 4, a Teflon resin or other resins, metal, resin-coated metal, and the like may be employed. In this case, they can be preferably used so long as they have resistance to a chemical agent such as an abrasive and the like which deposits on the brush.
[0022] Further, as to the strength of the main unit 4, it is preferably about 0 to 10 kg/cm2 and more preferably about 2 to 3 kg/cm2.
[0024] First, a high pressure water supply source is connected to the high pressure water introduction hole 7 which is opened to the lower surface of the main unit 4.
[0025] Although a connecting means is not particularly exemplified in the figure, a port may be screwed into the introduction hole 7 or any of known means may be employed.
[0026] In contrast, located in the inside of the recessed section 2 of the main unit 4 is the brush which is mounted on the polishing apparatus and used therein and in which a reaction product and a used fluid build up.
[0027] When the high pressure water is introduced through the introduction hole 7 in this state, the inside of the chamber section 5 is filled with the high pressure water.
[0028] As a result, the high pressure water is sprayed to the brush through the plurality of nozzle sections 6. Since the high pressure water is sprayed in a direction opposite to that when the brush is mounted on the polishing apparatus and used in it, the reaction product and the used fluid, which have built up in the inside of the brush, are easily fed to the inside of the brush together with the high pressure water.
[0029] Thereafter, the reaction product and the used fluid, which have built up in the inside of the brush, reach the central portion of the recessed section 2 together with the high pressure water introduced through the introduction hole 7 and then are discharged through the discharge hole 3 opened to the lower surface of the main unit 4.
[0030] That is, the reaction product and the used fluid, which have built up in the inside of the brush used in the polishing apparatus, can be reliably discharged only with the high pressure water.
[0031] Therefore, the brush can be restored to the initial state of it by the above operation and can be used again, whereby the operating cost of the polishing apparatus can be reduced.
[0032] Since the cleaning apparatus is very simply arranged as a whole, it can be manufactured at an inexpensive cost.
[0033] The pressure of the high pressure water and the period of time during which the high pressure water is introduced can be arbitrarily set depending upon the state of the reaction product and the used fluid which have built up in the inside of the brush.
[0034] Although both the recessed section and the chamber section are formed to a square, they may be toned to a square with round corners. That is, they may be formed to any arbitrary shape according to the shape of the brush to be used.
INDUSTRIAL APPLICABILITY
[0035] As described above, the cleaning apparatus according to the present invention is suitable for a cleaning apparatus for cleaning a brush, which is used in a polishing apparatus for polishing a workpiece such as a semiconductor wafer, a CD disc and the like whose surface is mirror-finished and which is required to have a uniform thickness, by means of an abrasive cloth. The cleaning apparatus can reliably remove the reaction product and the used fluid which have built up in the inside of the brush used in the polishing apparatus. The initial state of the brush itself can be restored thereby so that the brush can be used repeatedly.
1. A cleaning apparatus, characterized in that a recessed section, which has an open
upper surface and a size for permitting a brush to be located in the recessed section,
is formed to a main unit, a chamber section is formed in the inside of the main unit
so as to surround the recessed section, a plurality of nozzle sections are formed
to the main unit between the chamber section and the recessed section, and an introduction
hole communicating with the chamber section and a discharge hole communicating with
the recessed section are opened to the lower surface of the main unit, respectively.
2. A cleaning apparatus according to claim 1, wherein the recessed section is formed
to a square.
3. A cleaning apparatus according to claim 1, wherein the chamber section is formed to
a square surrounding the recessed section.