Semiconductor device manufacturing: process – Chemical etching – Vapor phase etching
Reexamination Certificate
2005-03-29
2005-03-29
Utech, Benjamin L. (Department: 1765)
Semiconductor device manufacturing: process
Chemical etching
Vapor phase etching
C438S710000, C438S712000, C438S720000
Reexamination Certificate
active
06872668
ABSTRACT:
An improved method is provided for etching back a tungsten layer that overlies a titanium nitride adhesion layer on a semiconductor structure. This method includes the steps of: (1) performing a first plasma etchback of the tungsten layer for a first predetermined time period, such that a thin layer of tungsten remains over the adhesion layer at the end of the first plasma etchback, (2) actively or passively cooling the resulting semiconductor structure to a temperature of 35° C. or lower, and then (3) performing a second plasma etchback of the tungsten layer until an endpoint is detected, thereby exposing the adhesion layer. Cooling the semiconductor structure prior to the second plasma etchback ensures that the titanium nitride adhesion layer is at a relatively low temperature during the second plasma etchback. The titanium nitride adhesion layer etches significantly slower at lower temperatures, thereby making it easier to stop the second plasma etchback on the adhesion layer.
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Cao Wanqing
Lee Shih-Ked
Lo Guo-Qiang
Xue Hongyong
Bever Hoffman & Harms LLP
Integrated Device Technology Inc.
Utech Benjamin L.
Vinh Lan
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