| 摘要 |
PURPOSE: A method for forming an isolation area in a semiconductor device is provided to improve the characteristic of device isolation by forming an oxynitride layer in a field oxide layer to prevent field recess. CONSTITUTION: A pad oxide and nitride layers(22a,23a) are formed on a semiconductor substrate(21a). A trench region is formed by etching selectively the pad oxide, nitride and the substrate in turn. After an oxide layer is deposited to fill up the trench region, it is flatten by CMP. An N2 ion is implanted on the whole surface to form an oxynitride layer in a field oxide layer(24). The pad nitride and oxide layers are removed during precleaning process.
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