Test pattern layout for test photomask and method for evaluating critical dimension changes
US9996000B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Apr 8, 2016 |
| Grant date | Jun 12, 2018 |
| Priority date | — |
| Expiry date | Apr 8, 2036 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F30/398
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.