Method for reducing shallow trench isolation edge thinning on tunnel oxides using partial nitride strip and small bird's beak formation for high performance flash memory devices
US6764920B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 19, 2002 |
| Grant date | Jul 20, 2004 |
| Priority date | — |
| Expiry date | May 6, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D84/038
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A method of semiconductor integrated circuit fabrication. Specifically, one embodiment of the present invention discloses a method for reducing shallow trench isolation (STI) corner recess of silicon in order to reduce STI edge thinning on tunnel oxides (510) for flash memories (devices M and N). An STI process is implemented to isolate flash memory devices (devices M and N) in the semiconductor structure (200). In the STI process, a nitride layer (210) is deposited over a silicon substrate (280). An STI region (290) is formed defining STI corners (240) where a top surface (270) of the silicon substrate (280) and the STI region (290) converge. The STI region (290) is filled with an STI field oxide and planarized until reaching the nitride layer (210). A local oxidation of silicon (LOCOS) is then performed to oxidize the top surface (270) of the silicon substrate adjacent to the STI corners (240). Oxidized silicon is grown to boost the thickness of a later formed tunnel oxide layer (510) at the STI corners (240).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.