CMOS structure with varying gate oxide thickness and with both different and like conductivity-type gate electrodes
US5497021A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 7, 1994 |
| Grant date | Mar 5, 1996 |
| Priority date | — |
| Expiry date | Dec 7, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D84/857
Abstract
After forming a gate oxide film on the surface side of a single crystalline silicon substrate, a first polycrystalline silicon layer is subsequently formed. After that, portions of polycrystalline silicon layers are left in each gate electrode formation region of a high voltage drive circuit. Then, the gate oxide film in a low voltage drive circuit side is removed while maintaining this state. Then, after forming a gate oxide film on those surface sides, a polycrystalline silicon layer is subsequently formed in the surface side. After that, impurities are introduced into the polycrystalline silicon layer to provide it with electrical conduction, and then portions of polycrystalline silicon layers are left.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.