TW282579B - Fabrication method of DRAM capacitor - Google Patents

Abstract

A fabrication method of DRAM capacitor, which is applicable to implement capacitor on semiconductor substrate with formed MOS transistor, comprises the steps of: forming insulator on the above semiconductor substrate; forming multiple polysilicon layers on the above insulator in sequence, and doped density of odd layer in the above polysilicon is different from the even's; forming trench deep through the above semiconductor substrate through one of the above polysilicon and either of drain and source of MOS transistor; forming down polysilicon on the above trench and polysilicon; forming masking layer on the above down polysilicon to confine down conductive layer of the above capacitor; with the above masking layer as mask implementing plasma etching to the above polysilicon, and due to different doped density either of odd and even layer in the above polysilicon forming isotropic etching, and the other forming anisotropic etching so as to make the above polysilicon form the above down conductive layer; removing the above masking layer; forming dielectric of the above capacitor on the above down conductive layer surface.