This paper presents a study of various well-known release techniques (bulk- and surface-micromachining) for the fabrication of movable silicon micromechanical structures. Their pro's and con's will be discussed. Further, a detailed study of a new self-aligned plasma technique is presented which uses silicon on insulator wafers (SOI). It has the ability to etch, release, and passivate MEMS in one ME run. Therefore, MEMS can be fabricated quickly, accurate, and at low costs