Shipping, handling, and storage of reticles

Abstract

Listen

Translate article

Reticles are used for printing IC patterns onto semiconductor wafers. In photolithography processing, defects in the images are converted to wafers after each exposure. In unfortunate cases, a large batch of wafers might be processed before the defects are detected. Multiple and repeating pattern defects on wafers have the biggest impact on the yield. Random defects can be generated during shipping, handling, or storage, often after inspection, as a consequence of particle deposition to charged reticles or damage of chrome lines due to Electrostatic Discharge (ESD) events. Killer particles and ESD-induced damage can lead to classic failures such as short circuits or opens. As the critical dimensions shrink to deep submicron regime, the susceptibility of reticle patterns to contaminants increases. In order to meet the requirements of next-generation lithography, a new version of the Asyst Single Reticle Pod (SRP) is developed. Reticles are encapsulated in the sealed pod to avoid particulate contamination in storage, as well as in manual or automatic transport. Constructed exclusively with static dissipative materials, the SRP provides effective protection for reticles from ESD-induced damage. Airborne Molecular Contamination (AMC) is minimized by carefully selecting the materials. In particular, the SRP is compatible with chemically amplified resists and does not cause problems such as optics hazing that could surface printable defects. Design principles and performance evaluations of the SRP are presented in this paper.