Dedicated test structure for the measurement of adhesion forces between contacting surfaces in MEMS devices

This paper reports on a new test structure that is designed for measuring adhesion forces that arise between contacting surfaces in microelectromechanical systems (MEMS). More specifically, the test structure allows one to measure the force that occurs when out-of-plane moving MEMS enter into mechanical contact with a bottom electrode. The test structure has been designed and fabricated in imec´s poly-SiGe MEMS platform. A measurement procedure that relies on the use of a laser Doppler vibrometer (LDV) has been elaborated. The measurement results that were obtained at different pressure levels and in dry environments as well as in environments with varying levels of relative humidity show how van der Waals and other adhesion forces can be measured using the device.