利用背面曝光技术制造大高宽比SU8结构的一种新方法

提出了一种解决大高宽比SU 8结构的新方法.该方法是将SU 8胶涂在一块掩模上,紫外光从掩模的背面照射,这样SU 8胶的曝光将从底部开始,不需要进行过曝光来保证底部胶的曝光剂量,从而很容易控制曝光剂量和SU 8胶结构的内应力.实验结果表明,该方法能够得到高宽比为32的SU 8结构,而文献报道的SU 8胶结构的高宽比最大仅为18

A New Method for Fabrication of SU8 Structures with a High Aspect Ratio Using a Mask-Back Exposure Technique

A new method is presented,which can obtain high aspect ratio in SU8 structures.Instead that the top of the photo resist layers are exposed to UV light through masks in conventional lithography,the new method utilizes a mask-back exposure technique,i.e.the SU8 resist layer coated on a mask surface (metal patterns on a glass plate),is irradiated by UV light through the back of the mask.So a desired exposure dose on the bottom of the resist layer can be easily achieved without over-exposing from its top.This has a two-fold effect,i.e.proper dose on the bottom of the resist and less internal stress.Initial experimental results show that compared to an aspect ratio of 18 obtained by conventional method,a higher aspect ratio of 32 in the SU8 structures can be achieved by this new method.