| 摘要 |
PURPOSE: An isolation layer formation method is provided to prevent coating fail of a photoresist layer and to restrain CD(Critical Dimension) and overlay reading fail by using two-step trench etching for STI(Shallow Trench Isolation) and DTI(Deep Trench Isolation). CONSTITUTION: A pad oxide layer(43), a pad nitride layer(45) and a hard mask are sequentially formed on a semiconductor substrate(41) defined by an STI region and a DTI region. A shallow trench is formed by selectively etching the hard mask, the pad nitride layer(45), the pad oxide layer(43) and the substrate(41). A negative photoresist pattern(53) is selectively formed in the shallow trench. A deep trench(55) is formed by selectively etching the exposed substrate(41) of the DTI region using the negative photoresist pattern(53) as a mask. After removing the negative photoresist pattern(53), an isolating layer is filled into the shallow trench and the deep trench.
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