Two new methods to improve the lithography precision for SU-8 photoresist on glass substrate

This paper introduces two novel approaches to effectively eliminate the influence of the scattering light from the wafer chuck and enhance the lithography precision of the SU-8 photoresist on a glass substrate. The first method is based on the complete reflection of light from Si substrate, and the second one employs materials which has low optical transparency and can achieve complete absorption of the near ultraviolet light transmitted from the SU-8 photoresist and the glass substrate. The SU-8 structures produced by these two methods have much better profiles than those made by the conventional process, and the line width deviation is smaller than 1 μm. These two routines have advantages of simplicity, low cost, therefore are applicable to batch fabrication and can significantly enhance the performance of MEMS devices.