(19)
(11)EP 0 223 994 A3

(12)EUROPEAN PATENT APPLICATION

(88)Date of publication A3:
25.10.1989 Bulletin 1989/43

(43)Date of publication A2:
03.06.1987 Bulletin 1987/23

(21)Application number: 86114062.2

(22)Date of filing:  10.10.1986
(51)International Patent Classification (IPC)4H01L 21/00, H01L 21/76
(84)Designated Contracting States:
DE FR GB IT

(30)Priority: 30.10.1985 US 792931

(71)Applicant: International Business Machines Corporation
Armonk, N.Y. 10504 (US)

(72)Inventors:
  • Ogura, Seiki
    Hopewell Junction, N.Y. 12 533 (US)
  • Riseman, Jacob
    Poughkeepsie, N.Y. 12 602 (US)
  • Rovedo, Nivo
    Poughquag, N.Y. 12 570 (US)
  • Schulz, Ronald Norman
    Salt Point, N.Y. 12 578 (US)

(74)Representative: Mönig, Anton, Dipl.-Ing. 
IBM Deutschland Informationssysteme GmbH, Patentwesen und Urheberrecht
D-70548 Stuttgart
D-70548 Stuttgart (DE)


(56)References cited: : 
  
      


    (54)Method of forming a sub-micrometer trench structure on a semiconductor substrate


    (57) In the process of sidewall image transfer, a vertical step is etched in some material and then a conformal layer of some other material is deposited over the step. By reactive ion etching the conformal material can be anisotropically etched which results in a sidewall spacer of the second material on the vertical surfaces of the step material. By removing the step material, the free standing spacer can then be used as a mask. One area in which improvement is desired is in the selectivity of the etch of the spacer to the material immediately below it. Because of the limited number of materials and reactive ion etching gases it is difficult to avoid an etch in the underlying layer as the sidewall spacer is formed. A suitable etch stop is employed beneath the step material to avoid the problem. Because of the usual techno­logy, the spacer material is plasma deposited silicon nitride and the step material is photoresist. Polysilicon, aluminum or similar metal is employed as an etch stop, since it is not affected by a CF₄ based gas which is used to form the spacer.







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