Mask of amorphous hydrogenated carbon films applied to chemical polishing and chemical dicing of silicon wafers

Amorphous hydrogenated carbon (a-C:H) films deposited by r.f. chemical vapo ur deposition technique were studied as masks for the processes of chemical polishing and chemical dicing of silicon slices. After the photolithograph ic processing on selected areas, layers of a-C:H films of about 70 nm thick were deposited on the polished plane of silicon wafers and the a-C:H film was patterned by the lift-off process. The silicon samples chemically etche d in an aqueous solution of fluoridric, nitric and acetic acids (CP4) were observed by optical microscopy. For time intervals and chemical solution co mposition used, no thickness variations of the a-C:H film were observed. Mo reover, samples where the a-C:H film was removed by oxygen plasma etching w ere also observed, but no etch pits appeared on the underneath surfaces. (C ) 1999 Elsevier Science Ltd. All rights reserved.