US 11,988,955 B2
Pellicle and method for producing the same
Akinori Nishimura, Annaka (JP)
Assigned to SHIN-ETSU CHEMICAL CO., LTD., Tokyo (JP)
Filed by Shin-Etsu Chemical Co., Ltd., Tokyo (JP)
Filed on Feb. 6, 2023, as Appl. No. 18/106,110.
Application 18/106,110 is a continuation of application No. 17/556,368, filed on Dec. 20, 2021, granted, now 11,599,018.
Application 17/556,368 is a continuation of application No. 16/700,077, filed on Dec. 2, 2019, granted, now 11,237,474, issued on Feb. 1, 2022.
Claims priority of application No. 2018-226482 (JP), filed on Dec. 3, 2018.
Prior Publication US 2023/0185186 A1, Jun. 15, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. G03F 1/62 (2012.01)
CPC G03F 1/62 (2013.01) 8 Claims
 
1. An exposure method, comprising
performing an exposure by irradiating an exposure light to a photomask substrate through a pellicle, a photomask unit comprising the photomask substrate and the pellicle, and the pellicle being disposed on the photomask substrate, while operating the photomask unit in a scanning motion, wherein the pellicle comprises a pellicle film having a thickness of not more than 0.28 μm, and a film tension (film frequency) of the pellicle film stretched on the pellicle frame is 30 Hz or more, so that vibration of the pellicle film due to the scanning motion during the exposure is reduced, and
the scanning motion is carried out at a speed, at which the overlay of larger than 1 nm is caused when operating the photomask unit comprising the photomask substrate and the pellicle having not more than 28 Hz of a film tension (film frequency) of the pellicle film stretched on the pellicle frame.