Abstract
The mechanical properties of thin film are very critical for the performance of MEMS devices. Since Poly-silicon film is of great use in MEMS, this study investigates the surface modification by various plasma treatments to finely tune the chemical and mechanical properties of poly-silicon film. Various plasma treatments, including H 2 , O 2 , and NH 3 , were implemented to modify the original Si-Si film bonding, Young's modulus, and hardness of poly-silicon film. These were significant Si-O, Si-OH/Si-H and Si-NH 2 /Si-N bonds formed after O 2 , H 2 and NH 3 plasma treatment, respectively. According to the H analysis from SIMS depth profile of, the thickness of surface modified layer would be ranged from 50 to 120 nm. In summary, the surface modification with H 2 plasma can reduce the elastic modulus of poly-silicon film for about 32.3%; moreover, the following vacuum annealing will further reduce the elastic modulus for about 60.2%. Therefore, surface modification with an adequate plasma treatment would be an effective method to change the chemical and mechanical properties of poly-silicon film. © 2004 Materials Research Society.