United States Patent 3,537,921
November 3, 1970

Selective Hydrofluoric Acid Etching And Subsequent Processing
Bernard W. Boland

Filed February 28,1967
Image of US PATENT 3,537,921

Abstract of the Disclosure

A process for selectively etching silicon nitride, chromium, ultra thin silicon dioxide, etc. layers using a thin layer of silicon as a mask against hydrofluoric acid (HF) etchants. Then long diffusions, using indium, gallium, etc. are performed through a selectively etched silicon nitride mask into an underlying semiconductor without mask reprocessing cycles
Figure descriptions: cover graphic

  • Figure 1 is a flow chart illustrating a method embodying the present invention
  • Figure 2 is a series of schematic cross-sectional views aligned with the Figure 1 steps to illustrate a structure which may be expected when practicing the method of this invention.
  • Figure 3 shows an additional semiconductor structure made according to the methods of this invention.

 Citations [54]:
2,583,681 01/1952 Brittain et al. 3,193,418 07/1965 Cooper et al. 3,438,873 04/1969 Schmidt
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