Recent developments in experimental on-chip stiction research: a review

Abstract

Release-related stiction problems in Microelectromechanical Systems (MEMS) have been solved almost completely by the use of CO2 drying and vapour-phase HF etching, but in-use stiction still poses a reliability threat to these tiny machines. In this paper, a review is presented of the recent work on the experimental investigation of adhesion forces in MEMS. The Cantilever Beam Array (CBA) technique and its derivatives (two-sides clamped, arc-shaped, S-shaped, electrostatic actuation, sidewall contacts) is discussed first. Atomic Force Microscope (AFM) studies can be used to obtain a more accurate physical picture of nanoscale adhesion, but suffer from the fact that the contact geometry is not exactly the same as a true MEMS contact. Emphasis is placed on new techniques that can be used to investigate stiction between MEMS surfaces in situ dynamically on-chip by means of dedicated MEMS devices. Combination of these techniques with AFM is especially promising, as is the application of these techniques to microscale friction research.