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Investigation of macroscopic uniformity during CH4/H2 reactive ion etching of InP and its improvement by use of a guard ring

: Janiak, K.; Niggebrugge, U.


Journal of vacuum science and technology B. Microelectronics and nanometer structures 20 (2002), No.1, pp.105-108
ISSN: 0734-211X
ISSN: 1071-1023
ISSN: 2166-2746
ISSN: 2166-2754
Journal Article
Fraunhofer HHI ()
iii-v semiconductors; indium compounds; sputter etching; reactive ion etching; macroscopic uniformity; guard ring; wafer uniformity; ch4/h2 plasma; masked areas; inp

We investigated the wafer uniformity of the etch attack obtained by reactive ion etching of InP in a CH4/H2 plasma. We found that this process inherently tends to produce a rather nonuniform distribution of etch rates across InP wafers with the fastest etching occuring at the wafer edge. Nonuniformities of up to 35% are observed. We propose a simple model, which explains the observation by reactants, which originate from nonetched regions, diffuse parallel to the wafer surface, and locally enhance the etch rate. The nonuniformity can be efficiently counteracted by a proper choice of the process pressure or even completely avoided by the introduction of a guard ring. In addition we also found that the arrangement of the masked areas on the wafer influences the etch rate profile.