Ammonium hydroxide etch of photoresist masked silicon
US5976767A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 9, 1997 |
| Grant date | Nov 2, 1999 |
| Priority date | — |
| Expiry date | Oct 9, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/76895
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
The present invention relates to a process for selectively etching polysilicon utilizing an ammonia solution etchant that is selective to silicon dioxide and photoresist. In one embodiment of the inventive material, a polysilicon layer is formed over a semiconductor substrate. A photoresist layer is then formed over the polysilicon layer. A portion of the photoresist layer is selectively removed by an edge bead removal process along the edge of the semiconductor wafer so as to expose a portion of the polysilicon layer. The exposed polysilicon layer is selectively removed by an etch conducted at a temperature range from about 20.degree. C. to about 30.degree. C. with an ammonium hydroxide etchant having an ammonia concentration in the range of about 1% to about 5% by volume. The etch is selective to the photoresist layer. A second application of the inventive process is conducted upon a semiconductor substrate having thereon a silicon base layer, a pair of gate stacks each having a spacer thereon, a silicon dioxide layer formed upon the silicon base layer over the of gate stacks and defining therein a contact hole between the pair of gate stacks that terminates at the silicon base l…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.