a process for forming a microelectromechanical system device by a deep reactive ion etching process during which a substrate overlying a cavity is etched to form trenches that breach the cavity to delineate suspended structures . a first general feature of the process is to define suspended structures with a drie process , such that the dimensions desired for the suspended structures are obtained . a second general feature is the proper location of specialized features , such as stiction bumps , vulnerable to erosion caused by the drie process . yet another general feature is to control the environment surrounding suspended structures delineated by drie in order to obtain their desired dimensions . a significant problem identified and solved by the invention is the propensity for the drie process to etch certain suspended features at different rates . in addition to etching wider trenches more rapidly than narrower trenches , the drie process erodes suspended structures more rapidly at greater distances from anchor sites of the substrate being etched . at the masking level , the greater propensity for backside and lateral erosion of certain structures away from substrate anchor sites is exploited so that , at the completion of the etch process , suspended structures have acquired their respective desired widths .