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TSI process performance in a transformer-coupled plasma dry develop tool

1996; SPIE; Volume: 2724; Linguagem: Inglês

10.1117/12.241838

1996-756X

John M. Hutchinson, Yosias Melaku, Wendy Nguyen, Siddhartha Das,

Metal and Thin Film Mechanics

We investigated dry development of resist in the Lam Research TCP 9400SE plasma etcher to meet process specifications for tea 180 nm lithography generation. A full-wafer imaging interferometer was integrated onto the tool, and used to measure etch rates, uniformities and stability of same in-situ. Etch rates of greater than 5000 A/min and selectivities of greater than 15:1 of silylated to unsilylated resist can be obtained in oxygen plasmas in the TCP in the electrode temperature range studied. However, lateral etching (undercut) underneath patterned oxide islands was measured to be approximately 30 nm/min for a typical oxygen process and could not be eliminated in pure oxygen plasmas. To control the lateral etching, we investigated the use of SO 2 addition to the oxygen discharge. SO 2 addition was found to eliminate the lateral etching component of the resist etch and reduce the etch lag effect, while having a minimal reduction in the overall resist etch rate. We have used the SO 2 process to minimize the effect of over-etch on developed resist profiles.