| 摘要 |
A method for fabricating a semiconductor memory device is provided to prevent formation of a step on the surface of a silicon substrate by forming a gate of a select transistor on the silicon substrate while forming a PIP(poly insulator poly) transistor on a trench. A silicon substrate(100) having a trench(104) is prepared. After a first high-density N-poly layer is deposited on the surface of the silicon substrate, the first high-density N-poly layer is selectively etched to form a lower electrode on the trench. A dielectric layer and a second high-density N-poly layer are sequentially deposited along the surface of the substrate having the lower electrode. The second high-density N-poly layer and the dielectric layer are selectively etched so that a gate(113) is formed on the substrate while a capacitor(112) is formed on the trench. A source/drain(116) is formed in the substrate at both sides of the capacitor and the gate. After an interlayer dielectric(117) is formed on the resultant structure, the interlayer dielectric is planarized. The interlayer dielectric is selectively etched to form a contact hole(118) exposing a part of the capacitor and the source/drain. A metal interconnection(119) is formed in the contact hole.
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