On adhesion force of MEMS micro-cantilever with rough surface

The adhesion force remains one of the dominant failure mechanisms in Micro Electro-Mechanical Systems (MEMS). The micro cantilever is MEMS typical component. Based on the three hypotheses and molecule friction principle, a "cutting-ball" shape adhesion physical model of the micro cantilever with rough surface is presented firstly. By analyzing the Hamaker micro continuum medium principle and solid physics principle, a Wigner-Seitz (W-S) continuum medium consistency model is put forward. The gap revision coefficients of the body with face-centered cubic (fcc) structure are derived, which include attractive force and repulsive one. The mathematical model of adhesion force of the micro-cantilever with the pedestal is obtained. Finally, the adhesion force of 2.2mmx0.05mm silicon micro-cantilever coated by Ni with surface fineness classes 10, 11, and 12 is simulated. The nonlinear relationships between the adhesion force and distance are obtained. The maximal attract forces, 0.173N, 0.4825N and 1.13N, are got, which help to improve MEMS structure design, avoid micro-cantilever adhering and enhance MEMS device reliability.