Nitrogen implementation to minimize device variation
US7388262B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 16, 2004 |
| Grant date | Jun 17, 2008 |
| Priority date | — |
| Expiry date | Nov 16, 2024 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/0214
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A rapid thermal nitridation (RTN) process produces a nitrogen concentration gradient in an oxynitride layer to compensate for transistor threshold voltage effects from a thickness gradient in the oxynitride layer. The nitrogen concentration gradient is selected to allow greater dopant penetration through thicker gate dielectrics in PMOS transistors formed using the oxynitride layer. Any increases in threshold voltage due to thicker gate dielectrics are counteracted by corresponding decreases in threshold voltage due to dopant penetration, allowing consistent threshold voltage values to be maintained for all PMOS transistors on a single wafer. The nitrogen concentration gradient can be introduced by regulating the flow of nitrous oxide during RTN processing to cause an accumulation of atomic oxygen to develop within the process chamber. The atomic oxygen forms a concentration distribution that increases in the direction of nitrous oxide flow, and therefore removes incorporated nitrogen from the oxynitride layer in corresponding proportions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.