Patent ID: 11953448
Assignee: TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD.
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 15:
16. A method for defect inspection, comprising:
receiving a photomask having a surface and a plurality of patterns disposed on the surface;
obtaining a gray scale image of the photomask using a scanner of a lithography system;
defining a defect region in the gray scale image, using a computing system of the lithography system, wherein the defect region has at least a first region and a plurality of second regions, the first region has a gray scale value and a difference between the gray scale value of the first region and a gray scale reference, and each second region has a gray scale value and a difference between the gray scale value of the second region and the gray scale reference;
performing a first calculation, using the computing system of the lithography system, according to the difference between the gray scale reference and the gray scale values of the first region and the second regions in the defect region to obtain a score;
performing a second calculation, using the computing system of the lithography system, to obtain a graphical diagram,
wherein the first calculation and the second calculating are performed to improve an inspection to a hard mask/shielding layer extension defect, when two peaks are shown in the graphical diagram, determining the photomask to have a shielding layer extension defect, and when more than two peaks are shown in the graphical diagram, determining the photomask to have the hard mask/shielding layer extension defect; and
performing a first removal operation and a second removal operation when the photomask is determined to have the hard mask/shielding layer extension defect, and performing the second removal operation when the photomask is determined to have the shielding layer extension defect.