The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 01, 2021
Filed:
Oct. 18, 2019
Taiwan Semiconductor Manufacturing Co., Ltd., Hsinchu, TW;
TAIWAN SEMICONDUCTOR MANUFACTURING CO, , LTD., Hsinchu, TW;
Abstract
A method of evaluating a focus control of an extreme ultraviolet (EUV) lithography apparatus includes preparing a wafer exposed by using the EUV lithography apparatus. The wafer includes test patterns formed of a photoresist and having circular islands or holes prepared by multiple exposures of EUV at different foci of exposure. The method further includes measuring a roughness parameter of the test patterns and estimating a function representing a dependence of the roughness parameter on the focus. A best focus is estimated based on an extremum of the function. Exposure wafers are then exposed to EUV with the best focus. The exposure wafers include the test patterns. The roughness parameter for the test patterns on the exposure wafers obtained by exposing the exposure wafers at the best focus is periodically measured. An abnormality in focus is then determined based on the measured roughness parameter and the function.