| 摘要 |
<p>A method of forming a trench DMOS transistor (21) is provided which reduces punch-through. The method begins by providing a substrate (100) of a first conductivity type. A body region (116), which has a second conductivity type, is formed on the substrate. A masking layer (120) is formed which defines at least one trench (124). Next, the trench and an insulating layer (150, 130) that lines the trench are formed. A conductive electrode (152) is then formed in the trench, which overlies the insulating layer. A source region (140) of the first conductivity type is formed in the body region adjacent to the trench. The step of forming the trench may include the steps of etching the trench and smoothing the sidewalls of the trench with a sacrificial oxide layer (150) before removal of the masking layer that defines the trench. The step of forming the conductive electrode (152) may include the steps of depositing a layer of undoped polysilicon followed by a layer of doped polysilicon.</p> |
