Agere Systems Inc.

Mario Pita

Milton Beachy

Daniel Charles Kerr

Gerald Warren Gibson, Jr

Thomas Craig Esry

Thomas M Oberdick

A method of preventing formation of stringers adjacent a side of a CMOS gate stack during the deposition of mask and poly layers for the formation of a base and emitter of a bi-polar device on a CMOS integrated circuit wafer. The stringers are formed by incomplete removal of a hard mask layer over an emitter poly layer over a nitride mask layer. The method includes overetching the hard mask layer with a first etchant having a higher selectivity for the emitter poly material than for the material of the hard mask, determining an end point for the overetching step by detection of nitride in the etchant and applying a poly etchant that is selective with respect to nitride to remove any residual emitter poly.

Stringer elimination in a BiCMOS process

A method for forming a trench in a semiconductor silicon substrate. An anti-reflective coating layer and a photoresist layer are formed over the substrate and patterned in accordance with a location for the trench. During the trench etch into the silicon substrate, the etch environment is monitored to detect the material of the anti-reflective coating layer. The etch process is controlled in response to detecting the removal of this material and the known etch rate differential between the anti-reflective coating material layer and the silicon substrate.

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Harmony, FL, United States of America

Mario Pita