发明授权
US07563675B2 Ladder poly etching back process for word line poly planarization 有权
用于字线多平面化的梯形多层刻蚀工艺

Ladder poly etching back process for word line poly planarization
摘要:
A method is disclosed for etching a polysilicon material in a manner that prevents formation of an abnormal polysilicon profile. The method includes providing a substrate with a word line and depositing a polysilicon layer over said substrate and word line. An organic bottom antireflective coating (BARC) layer is then deposited over said polysilicon layer. A ladder etch is performed to remove the BARC layer and a portion of the polysilicon layer. The ladder etch consists of a series of etch cycles, with each cycle including a breakthrough etch and a soft landing etch. The breakthrough and soft landing etches are performed using different etchant gases, and at different source and bias powers, pressures, gas flow rates, and periods of time. The ladder etch results in a smooth polysilicon surface without abrupt steps.
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