| 摘要 |
A stress enhanced MOS transistor and methods for its fabrication are provided. In one embodiment the method comprises forming a gate electrode overlying and defining a channel region in a monocrystalline semiconductor substrate. A trench having a side surface facing the channel region is etched into the monocrystalline semiconductor substrate adjacent the channel region. The trench is filled with a second monocrystalline semiconductor material having a first concentration of a substitutional atom and with a third monocrystalline semiconductor material having a second concentration of the substitutional atom. The second monocrystalline semiconductor material is epitaxially grown to have a wall thickness along the side surface sufficient to exert a greater stress on the channel region than the stress that would be exerted by a monocrystalline semiconductor material having the second concentration if the trench was filled by the third monocrystalline material alone. |
