Process temperature-dependent mechanical properties of polysilicon measured using a novel tensile test structure

作者：Kamiya Shoji^*; Kuypers Jan H; Trautmann Achim; Ruther Patrick; Paul Oliver

来源：Journal of Microelectromechanical Systems, 2007, 16(2): 202-212.

DOI：10.1109/JMEMS.2007.892920

• fracture strength
• residual stress
• tensile test
• Young's modulus

A new test structure was developed to measure three major unknown mechanical parameters of deposited thin films, i.e., fracture strength, Young's modulus, and residual stress. The structure was designed to have plural specimens of a deposited thin film bridging the gap of the silicon substrate and enables the easy and efficient tensile testing of the film. It was used to measure those parameters of various polysilicon films. Polysilicon is commonly used as a structural material of microelectromechanical systems (MEMS) after being deposited at a temperature below 600 degrees C and annealed at a temperature around 1000 degrees C to remove the residual stress. On the other hand, polysilicon can be also deposited at a temperature higher than 600 degrees C. The three parameters of polysilicon films depend on process temperature and were evaluated using the new test structure. Concerning the strength, films deposited at 560 degrees C had the highest strength when annealed at 850 degrees C. Films deposited at 625 degrees C and annealed at 1050 degrees C were weaker than those deposited at 560 degrees C and annealed at 1050 degrees C. Young's modulus was found to behave in a similar way. The trend of the residual stress was the same as already reported, but its local evaluation was possible in combination with the tensile strength determination.

• 出版日期2007-4