A novel aluminum on quartz mask for excimer laser projection ablation

Abstract

Current excimer laser projection ablation dielectric masks consist of alternating layers of high and low refractive indexes dielectric material on a quartz substrate. Despite the successful use of dielectric masks in the manufacturing environment, due to issues such as fabrication process complexity, high cost compared to chromium on quartz masks, and limited number of mask vendors, the dielectric masks have remained a specialty masks. As an alternative, the authors have developed a novel aluminum on quartz mask structure which can withstand the high laser fluence demand of 1X stepper ablation tools and repetitive usage in manufacturing environment, in addition to the process being economical. The mask structure defined is very similar to the chromium on quartz mask used for photolithography. The proposed mask structure has the advantages of a low cost, a use for multiple wave-length ablation, and a simple fabrication process. The three different mask fabrication processes are described in this paper. The ablation characteristics and the image size control obtained for different mask fabrication processes are also described. The static single pulse and repetitive long term damage fluence threshold for the mask have been determined. All of the results obtained show that aluminum on quartz structure is highly suitable for excimer laser projection ablation process and is completely compatible to existing 1X projection tooling.