Patent ID: 9372394
Filing Date: 2016-06-21
CPC Classification: G03F,G06F

Claim Text:
1. A test pattern layout for a test photomask, the test pattern layout comprising: a plurality of cells having a varied density pattern, the plurality of cells including: a first group of cells arranged along a first line, the first group of cells having a first combined density ratio, each cell in the first group of cells having a respective density ratio and wherein the first combined density ratio is a total of the respective density ratios for each cell in the first group of cells; and a second group of cells arranged along a second line, the second group of cells having a second combined density ratio, each cell in the second group of cells having a respective density ratio and wherein the second combined density ratio is a total of the respective density ratios for each cell in the second group of cells, wherein the second combined density ratio for the second group of cells is equal to the first combined density ratio of the first group of cells, and wherein no respective density ratio of a cell in either the first group of cells or the second group of cells is equal to the respective density ratio of another cell in either the first group of cells or the second group of cells.