Process including silo-chloro passivation for etching tungsten silicide overlying polysilicon

a technology of tungsten silicide and etching process, which is applied in the field ofplasma etching, can solve the problems of increasing difficulties, severe etching process requirements, and shrinkage, and achieve the effects of reducing the depth microloading, reducing the residence time of etching, and increasing the selectivity of silicon
US20070281479A1Inactive Publication Date: 2007-12-06APPLIED MATERIALS INC
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Patent Information

Authority / Receiving Office
US · United States
Patent Type
Applications(United States)
Current Assignee / Owner
APPLIED MATERIALS INC
Publication Date
2007-12-06
Estimated Expiration
Not applicable · inactive patent

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Abstract

A method of plasma etching tungsten silicide over polysilicon particularly useful in fabricating flash memory having both a densely packed area and an open (iso) area requiring a long over etch due to microloading. Wafer biasing is decreased in the over etch. The principal etchant include NF3 and Cl2. Argon is added to prevent undercutting at the dense / iso interface. Oxygen and nitrogen oxidize any exposed silicon to increase etch selectivity and straightens the etch profile. SiCl4 as an example of a silicon and chlorine containing passivating gas may be added for additional selectivity.
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Description

RELATED APPLICATION

[0001] This application is a division of Ser. No. 11 / 445,709 filed Jun. 2, 2006.FIELD OF THE INVENTION

[0002] The invention relates generally to plasma etching. In particular, the invention relates to etching tungsten and other tungsten-containing materials over silicon.BACKGROUND ART

[0003] Flash memory has assumed an increasingly important position in semiconductor memory technology. It provides relatively fast non-volatile rewritable memory, which is particularly attractive in mobile applications such as cell phones, portable music players, and other devices which rely upon battery power but are often turned off for extended periods. Nonetheless, flash memory chips are being economically fabricated which have a capacity of greater than a gigabit.

[0004] However, large-capacity flash memories of the desired characteristics have been accomplished by aggressively reducing the area of the memory cells, by reducing the thickness of many of the important layers, and by rely...

Claims

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