A sticking model of suspended polysilicon microstructure including residual stress gradient and postrelease temperature

• Published in: Journal of microelectromechanical systems Vol. 7; no. 3; pp. 339 - 344
• Main Authors: YEE, Y, PARK, M, CHUN, K
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.09.1998; Institute of Electrical and Electronics Engineers
• Subjects: Applied sciences; Bending moments; Cantilever beams; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Fluid surfaces and fluid-fluid interfaces; Mathematical models; Mechanical engineering. Machine design; Micromachining; Microstructure; Physics; Precision engineering, watch making; Residual stresses; Rough surfaces; Stiction; Structural beams; Substrates; Surface energy (surface tension, interface tension, angle of contact, etc.); Surface roughness; Surface tension; Surface treatment; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Temperature; Thermal effects; Precision engineering; Micromachining; Polycrystal; Temperature effect; Rinsing; Cantilever; Adhesion; Modeling; Cantilever beam; Temperature gradient; Liquid; Silicon; Surface tension; Miniaturization; Residual stress; Electromechanical system
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/84.709653

A sticking (stiction) model for a cantilevered beam is derived. This model includes the effect of the bending moment, which stems from stress gradient along the vertical direction of structural polysilicon, and the temperature during the release process. The bending moment due to the stress gradient will play an important role in evaluating antisticking efficiency since liquid tension and surface energy of microstructures tend to become smaller by newly developed antisticking techniques. The effects of stress gradient and temperature were analyzed and verified with surface-micromachined polysilicon cantilevers. By modifying the substrate polysilicon with grain-hole formation technique, the effects of residual stress gradient in polysilicon on stiction could be observed in the condition of low work of adhesion.