| 摘要 |
Adding nitrogen to the Si-SiO2 interface at STI sidewalls increases carrier mobility in MOS transistors, but control of the amount of nitrogen has been problematic due to loss of the nitrogen during liner oxide growth. This invention discloses a method of forming STI regions which have a controllable layer of nitrogen atoms at the STI sidewall interface. Nitridation is performed on the STI sidewalls by exposure to a nitrogen-containing plasma, by exposure to NH3 gas at high temperatures, or by deposition of a nitrogen-containing thin film. Nitrogen is maintained at a level of 1.0.1015 to 3.0.1015 atoms/cm2, preferably 2.0.1015 to 2.4.1015 atoms/cm2, at the interface after growth of a liner oxide by adding nitrogen-containing gases to an oxidation ambient. The density of nitrogen is adjusted to maximize stress in a transistor adjacent to the STI regions. An IC fabricated according to the inventive method is also disclosed.
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