International Business Machines Corporation

Siemens Aktiengesellschaft

Elke Eckstein

Waldemar Walter Kocon

Marc Jay Weiss

Birgit Hoffman, Deceased

Edward William Kiewra

A back end of the line dry etch method is disclosed. Etching of a mask oxide and temporary (sacrificial) silicon mandrel occurs following the formation of gate stacks and tungsten studs. The mask oxide is etched selectively to tungsten and silicon through the use of a polymerizing oxide etch. The silicon is etched selectively to both silicon nitride, silicon oxide, and tungsten. The process removes the silicon mandrel and associated silicon residual stringers by removing backside helium cooling, while using HBr as the single species etchant, and by adjusting the duration, the pressure, and the electrode gaps during the silicon etch process. The silicon may be undoped polysilicon, doped polysilicon, or single crystal silicon.

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Paris, France

Elke Eckstein