| 摘要 |
1522755 Semiconductor devices NCR CORP 7 July 1976 [25 July 1975] 28230/76 Heading H1K A method of producing openings for contact regions 18, 20, Fig. 2, for source and drain regions 12.1, 12.1<SP>1</SP> and 12.3, 12.3<SP>1</SP> respectively of IGFETS 12, 12<SP>1</SP> comprises two steps of providing a field oxide layer 24, Fig. 7, on the substrate covering two contact regions, etching the field oxide layer to expose selected areas of the contact regions, Fig. 5 (not shown), forming a plurality of superimposed gate insulating layers 28, 30, 32 on the field oxide layer and on the exposed areas of the contact regions, and etching selectively two gate insulating layers to expose areas of the contact regions that are smaller than the said selected areas. Preferably, the source and the drain regions, the lead conductors 14, 16 and the contact regions 18, 20 are produced by the same diffusion step involving the use of an oxide maze (22), Fig. 3 (not shown). A solution of ammonium fluoride and hydrogen fluoride etching oxide layer 28 at a faster rate as compared to its rate of etching nitride layer 30, is employed to form openings 36, 38, Fig. 9. |
