| 摘要 |
PURPOSE: A method for forming an isolation layer of a semiconductor device is provided to improve isolation property by preventing the isolation layer from being depressed at a boundary with an active region. CONSTITUTION: In the method, a buffer oxide layer, a CVD oxide layer and the first nitride layer are formed on a semiconductor substrate, and then the nitride layer is selectively removed. Next, the oxide layers are etched to expose a portion of the substrate through the nitride layer. The second nitride layer is then formed over the substrate and planarized until the CVD oxide layer is exposed. Next, the CVD oxide layer and the buffer oxide layer are removed, and an oxide sidewall is formed on a negative sloping side of the remaining second nitride layer. The exposed portion of the substrate is then etched through the oxide sidewall to form a trench. After that, an insulating layer is deposited enough to fill the trench and then planarized until the nitride layer is exposed. The nitride layer is then removed and the insulating layer is etched back to obtain the isolation layer(28) partly staying over the trench.
|
