Optimization of photoresist plating mold fabrication for metal mask patterning

Abstract

In this paper, we present results on optimization of photoresist (PR) plating molds for patterning of a nickel masking layer. The process can be adopted in a number of processes, including deep reactive ion etching of strongly bonded materials with high chemical resistance, such as fused silica (FS), borosilicate glass, and silicon carbide. The desirable plating mold attributes, such as thick PR, controlled dimension, vertical sidewall angle, and low sidewall roughness were optimized by varying exposure dose, exposure contact mode, developer dilution ratio, and PR type. We demonstrated that the PR dimensions decrease proportionally to increase of the exposure dose, where the relationship was utilized to control fabricated dimensions. To improve the sidewall angle, lowering the exposure dose was shown to reduce sidewall tapering, with further improvements possible by applying the vacuum contact exposure mode. Furthermore, we showed that by using a chemically enhanced PR, such as AZ®12XT, smooth PR sidewalls can be attained. The benefits of optimizing PR features were verified through an FS etch experiment and demonstrated a vertical etch with controlled dimension, smooth sidewall, and reduced faceting.