Study of Feature Dimensions of SU-8 High-aspect-ratio Microstructures

• Main Authors: Li-Chung Hsieh, 謝立中
• Other Authors: none
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/34732553029859728587

碩士 === 國立高雄第一科技大學 === 機械與自動化工程研究所 === 99 === The present study aims to produce high-aspect-ratio SU-8 micro-gear structures in the lithography process of MEMS UV-LIGA technology, and also to study the effect of the UV-light diffraction on the sidewall inclination. Different thin-film materials with various reflective index are coated or produced on the silicon wafer surface to study the Fresnel diffraction effect. The Taguchi method is adopted here. The surface coating materials, exposure gap, exposure dose, and resist thickness are chosen as four control factors. The effects of these factors on the photoresist sidewall inclination and also its dimension are investigated. The photoresist microstructure is fabricated by the UV-LIGA process. Experiments are conducted to study the effects of the control factors. In this study, the best combination for the sidewall inclination angle is A1 (film material: TiN)、B1(Exposure Gaps: 10um)、C2(Dosage: 450 mJ/cm2)、D3(PR thickness: 500um), while the best combination for the gear width is A3 (film material: SiO2)、B1(Exposure Gaps: 10um)、C3(Dosage: 500 mJ/cm2)、D3(PR thickness: 500um). The most dominant factor is confirmed to be the surface coating materials. The optimal combination is proved to achieve the intended improvement for the sidewall inclination angle and also the gear width.