Oxide deglaze before sidewall oxidation of mesa or trench
US5863827A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 3, 1997 |
| Grant date | Jan 26, 1999 |
| Priority date | — |
| Expiry date | Jun 3, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/76235
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A shallow trench isolation (STJ) (10) is used to isolate two active regions (12) from each other. The advantage of STI (10) is that the upper corners (14) are rounded. Rounding of the upper corners (14) is accomplished using an oxide deglaze prior to sidewall oxidation of the trench which undercuts the pad oxide (20) from the pad nitride (22). The allows the sidewall oxidation process to form a thicker oxide at upper corners (14) which in turn, rounds the corners. Rounded corners (14) minimum the electric field strength induced by the geometry. As a result, the Vt lowering that occurs in prior art STI structures is minimized and off-state leakage due to the inherent parasitic transistor at the upper corner is reduced.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.