Collar formation using selective SiGe/Si etch

Details Collar formation using selective SiGe/Si etch Collar formation using selective SiGe/Si etch

2005-08-02

2005-08-02

Whitehead, Jr., Carl (Department: 2813)

Semiconductor device manufacturing: process

Making passive device

Trench capacitor

C438S269000, C438S706000, C438S719000

Reexamination Certificate

active

06924205

ABSTRACT:
A method of forming collar isolation for a trench storage memory cell structure is provided in which amorphous Si (a:Si) and silicon germanium (SiGe) are first formed into a trench structure. An etching process that is selective to a:Si as compared to SiGe is employed in defining the regions in which the collar isolation will be formed. The selective etching process employed in the present invention is a wet etch process that includes etching with HF, rinsing, etching with NH4OH, rinsing, and drying with a monohydric alcohol such as isopropanol. The sequence of NH4OH etching and rinsing may be repeated any number of times. The conditions used in the selective etching process of the present invention are capable of etching a:Si at a faster rate than SiGe.

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patent: 2003/0062568 (2003-04-01), Beintner

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