Test pattern layout for test photomask and method for evaluating critical dimension changes

摘要

Aspects of the present invention relate to a test photomask and a method for evaluating critical dimension changes in the test photomask. Various embodiments include a test photomask. The test photomask includes a plurality of cells having a varied density pattern. The plurality of cells include a first group of cells arranged along a first line, the first group of cells having a first combined density ratio. The plurality of cells also include a second group of cells arranged along a second line, the second group of cells having a second combined density ratio. In the plurality of cells, 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. The varied density pattern is configured to substantially neutralize fogging effects.

主权项

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.