Development of a new pellicle for use with the new generation reticle

Abstract

This paper is intended to cover three issues related to the development of the new pellicles suitable for use with the new generation reticles, namely (1) frame shape and size; (2) frame stand-off (height); and (3) frame thickness, to reflect results and advancements achieved in our recent studies. (1) Frame shape and size: We found that the four-cornered shape best suits our purposes. As for its size, there is already large-size product currently available for LCDs in the marketplace. (2) Frame stand-off (height): While pellicle manufacturers require high stand-off to maintain pellicle strength and ease of handling, mask shop manufacturers and inspection equipment manufacturers prefer lower stand-off, for lesser blind area. Certain users requested that the new inspection equipment be available to check 6' reticles that are currently in use. As a result, the 6.3 mm stand-off combined with the trapezoidal shape was chosen to be best suited to insure wider inspection area. (3) Frame thickness: As the membranae of the pellicle adheres to the frame, the membrane tension towards the inside causes some frame distortion. Our investigation proved that distortions (maximum 0.1 mm) were present in the case of 6' frames. We examined the relationship between the frame thickness and frame distortion. Another problem arises when the pellicle is mounted on a reticle: that is reticle distortions can occur. We found that the distortions can be reduced through the use of a new type of mask adhesive.