SU-8胶与基底结合特性的实验研究

Experimental Research on Adhesive Characteristics Between SU-8 Resist and Substrate

SU - 8胶是一种负性、环氧树脂型、近紫外线光刻胶。它适于制作超厚、高深宽比的MEMS微结构。为电铸出金属微结构 ,通常需要采用金属基底。但SU - 8胶对金属基底的结合力通常不好 ,因而限制了其深宽比的提高。从SU - 8胶与基底的浸润性、基底表面粗糙度以及基底对近紫外光的折射特性入手 ,对SU - 8胶与基底的结合力进行分析 ,首次指出 :在近紫外光的折射率高的基底与SU - 8胶有很好的结合性。经实验得出经过氧化处理的Ti片与SU - 8胶结合性强。这有利于为MEMS提供低成本、高深宽比的金属微结构。

SU-8 is a negative, epoxy type, near-UV photoresist.The resist has been specifically developed for ultrathick and high-aspect-ratio MEMS-type applications. In order to get a metallic microstructure, the substrate should always be metallic film. But this photoresist, in practice, has been proved to be poor adhesion with metallic substrate.Therefore the aspect ratio is limited. In this paper, the adhesive characteristics between SU-8 resist and the metallic substrate are analyzed based on the following factors, such as the wetting property between SU-8 and substrate, the roughness of the substrate and the refractive index of the substrate to near-UV.Based on the analyses,the high refractive index of the substrate to near-UV shows comparatively good adhesion with SU-8.The substrate of Ti film with oxidation treatment has the stronger adhesive to the resist. The above results will open the possibilities to provide MEMS with the metallic microstrcture of low cost and high aspect-ratio.