Mechanical characterization of KMPR by nano-indentation for MEMS applications

The elastic modulus and hardness of a novel negative photoresist, KMPR, under different heat treatment temperatures, have been characterized in this work using a combination of nanoindentation, uniaxial tension and vibration tests. There are two major conclusions. First, the material exhibits strong anisotropy. The apparent modulus obtained by the indentation method (6.5-7.5GPa) is higher than that characterized by the uniaxial tensile test (1.07GPa). The modulus issue is further validated by the subsequent vibration test data. Second, the apparent modulus and the apparent hardness vary with heat treatment temperatures. The room temperature elastic modulus decreased with an increase of the processing temperature but the apparent hardness essentially exhibited an opposite trend. It is suggested that this unusual result was caused by the pile-up effect during the indentation process.