Journal of Electronic Materials
December 2015, Volume 44, Issue 12, pp 4891-4897
J. FAN,1,2 T. ZHU,1 W.J. WU,1 S.H. TANG,1 J.Q. LIU,1 and L.C. TU1,2,3
1.—MOE Key Laboratory of Fundamental Physical Quantities Measurement, School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China.
2.—Institute of Geophysics, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China.
3.—e-mail: tlc@hust.edu.cn
Photosensitive polyimide (PSPI) based insulating layer fabrication for microelectromechanical systems (MEMS) application has been systematically investigated in this work. The PSPI was spin coated on a silicon substrate as an insulating layer between two metal lines. In consideration of thermal properties, a low temperature hard bake process was carefully optimized. Finally, the polyimide insulating layer was hardened by exposure to air at 80°C for 120 min + 150°C for 60 min + 180°C for 60 min + 250°C for 60 min + 350°C for 60 min in a dry furnace. Using this optimized hardening process, the outgassing effect in post-fabrication heat treatment can be completely eliminated, which presented an excellent thermal resistance in MEMS fabrications. The reliability test was accomplished through an immersion in organic solvent and acid/base solution in order to verify the corrosion resistance of the PSPI frame for insulating application. The excellent resistance which is on the order of 108 Ω between two metal lines, shows an outstanding insulating property.
Keywords: Photosensitive polyimide (PSPI)，hard bake parameters，thermal resistance，reliability test，insulation，MEMS
Springer Link: http://link.springer.com/article/10.1007/s11664-015-4076-y
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