finFET Isolation by Selective Cyclic Etch

摘要

Etching interleaved structures of semiconductor material forming fins of finFETs and local isolation material interposed between the fins is performed alternately and cyclically by alternating etchants cyclically such as by alternating gases during reactive ion etching. Etchants are preferably alternated when one of the semiconductor material and the local isolation material protrudes above the other by a predetermined distance. Since protruding surfaces are etched more rapidly than recessed surfaces, the overall etching process is accelerated and completed in less time such that erosion of other materials to which the etchants are less than optimally selective is reduced and allow improved etching of trenches for improved isolation structures to be formed.

主权项

1. A method for forming a trench for an isolation structure from a structure including excess fins formed from a layer of semiconductor material with local isolation material deposited between said fins, said method comprising steps of
depositing hard mask material over a portion of said local isolation material and selected ones of said fins, patterning said hard mask material, and cyclically etching said excess fins selectively to said hard mask material and said local isolation material alternatingly with etching said local isolation material selectively to said excess fins and said hard mask material in respective etching cycles to form a trench between said selected ones of said fins while limiting protrusion of portions of said excess fins above portions of said local isolation material and limiting protrusion of portions of said local isolation material above said portions of said excess fins.