Evaluation of Easily Removable Pellicle Adhesive

With the advancement of technology, the need to produce flatter photomasks is critical to meet strict mask manufacturing requirements. Components such as pellicle mounting techniques, pellicle frame height, frame material and adhesive all play an important role in finished photomask flatness.1-5 In particular, recent studies have shown that adhesive flexibility affect final photomask flatness significantly.6 This has motivated pellicle suppliers to optimize adhesive properties in addition to evaluate new adhesives. The paper describes the joint evaluations between IBM, Toppan and MLI, performed to determine the effect of a new MLI adhesive on the distortion of photomasks. Due to the nature of this adhesive, minimal mounting force is required. As a result of utilizing extreme low mounting pressure, benefits such as decreased flatness distortion and ease of adhesive removal are observed. The goal of this paper is to evaluate this new adhesive offering and understand the various impacts it has on pelliclized photomasks for advanced technologies.