A SURVEY ON THE REACTIVE ION ETCHING OF SILICON IN MICROTECHNOLOGY

This article is a brief review of dry etching as applied to pattern tr ansfer, primarily in silicon technology. It focuses on concepts and to pics for etching materials of interest in micromechanics. The basis of plasma-assisted etching, the main dry etching technique, is explained and plasma system configurations are described such as reactive ion e tching (RIE). An important feature of RIE is its ability to achieve et ch directionality. The mechanism behind this directionality and variou s plasma chemistries to fulfil this task will be explained. Multi-step plasma chemistries are found to be useful to etch, release and passiv ate micromechanical structures in one run successfully. Plasma etching is extremely sensitive to many variables, making etch results inconsi stent and irreproducible. Therefore, important plasma parameters, mask materials and their influences will be treated. Moreover, RIE has its own specific problems, and solutions will be formulated. The result o f an RIE process depends in a non-linear way on a great number of para meters. Therefore, a careful data acquisition is necessary. Also, plas ma monitoring is needed for the determination of the etch end point fo r a given process. This review is ended with some promising current tr ends in plasma etching.