Process for etching tungsten silicide overlying polysilicon particularly in a flash memory
US7754610B2 · kind B2 · utility
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13References
35Claims
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Key dates
| Filing date | Jun 2, 2006 |
| Grant date | Jul 13, 2010 |
| Priority date | — |
| Expiry date | Sep 26, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D64/035
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A method of plasma etching tungsten silicide over polysilicon particularly useful in fabricating flash memory having both a densely packed area and an open (iso) area requiring a long over etch due to microloading. Wafer biasing is decreased in the over etch. The principal etchant include NF3 and Cl2. Argon is added to prevent undercutting at the dense/iso interface. Oxygen and nitrogen oxidize any exposed silicon to increase etch selectivity and straightens the etch profile. SiCl4 may be added for additional selectivity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.