TRENCH CAPACITOR DRAM PROCESS WITH PROTECTED TOP OXIDE DURING STI ETCH

摘要

An array top oxide is protected in the manufacture of vertical metal oxide semiconductor field effect transistor (MOSFET) dynamic random access memory (DRAM) arrays by a protective etch stop layer (18) which protects the top oxide (16) and prevents word line to substrate shorts and/or leakage. Processing of a DRAM device containing vertical MOSFET arrays proceeds through planarization of the array gate conductor polysilicon (17) of the vertical MOSFET to the top surface of the top oxide (16). A thin polysilicon layer (18) is deposited over the planarized surface and an active area (AA) pad nitride and tetraethyl orthosilicate (TEOS) stack is deposited. The AA mask is used to open the pad layer to the silicon surface, and shallow trench isolation (STI) etching is used to form isolation trenches (20).