Stringer elimination in a BiCMOS process
US7700491B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 10, 2005 |
| Grant date | Apr 20, 2010 |
| Priority date | — |
| Expiry date | Feb 18, 2029 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D84/038
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A method of preventing formation of stringers adjacent a side of a CMOS gate stack during the deposition of mask and poly layers for the formation of a base and emitter of a bi-polar device on a CMOS integrated circuit wafer. The stringers are formed by incomplete removal of a hard mask layer over an emitter poly layer over a nitride mask layer. The method includes overetching the hard mask layer with a first etchant having a higher selectivity for the emitter poly material than for the material of the hard mask, determining an end point for the overetching step by detection of nitride in the etchant and applying a poly etchant that is selective with respect to nitride to remove any residual emitter poly.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.