Patent ID: 8513135
Filing Date: 2013-08-20
Classification: H01L

Abstract:
1. A method of etching a material layer, comprising: forming a patterned temporary material having sidewalls and a horizontal surface over an underlying material; forming an oxide material onto the patterned temporary material; removing the oxide material from the horizontal surface of the patterned temporary material to form oxide spacers on the sidewalls of the patterned temporary material; removing the patterned temporary material to form vertical, free-standing and spaced-apart oxide spacers having a length, vertical surfaces with convex and concave portions, and an initial critical dimension that is variable along the length; exposing the vertical, free-standing and spaced-apart oxide spacers to an ammonium fluoride gas to convert the convex portions of the vertical surfaces of the vertical, free-standing and spaced-apart oxide spacers to a heat decomposable compound; removing at least a portion of the heat decomposable compound to obtain a uniform critical dimension along the length of the vertical, free-standing and spaced-apart oxide spacers; and removing the underlying material exposed within openings between the vertical, free-standing and spaced-apart oxide spacers.