Pellicle transmission uniformity requirements

Abstract

Controlling critical dimensions of devices is a constant battle for the photolithography engineer. Current DUV lithographic process exposure latitude is typically 12 to 15% of the total dose. A third of this exposure latitude budget may be used up by a variable related to masking that has not previously received much attention.The emphasis on pellicle transmission has been focussed on increasing the average transmission. Much less, attention has been paid to transmission uniformity. This paper explores the total demand on the photospeed latitude budget, the causes of pellicle transmission nonuniformity and examines reasonable expectations for pellicle performance. Modeling is used to examine how the two primary errors in pellicle manufacturing contribute to nonuniformity in transmission.World-class pellicle transmission uniformity standards are discussed and a comparison made between specifications of other components in the photolithographic process. Specifications for other materials or parameters are used as benchmarks to develop a proposed industry standard for pellicle transmission uniformity.

Pellicle Life-Testing for High Exposure Dose Applications

“…Significant characterization and life-time testing has been done on pellicle materials as lithography systems have evolved from g-line (436 nm) to ArF excimer laser deep UV (193 nm) wavelengths [4,5,6,7,8,9]. This testing provided valuable information for both pellicle manufacturers and users to meet the technology roadmap for resolution and pattern placement requirements and system throughput.…”