Point diffraction interferometric mask inspection tool and method
US6559953B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | May 16, 2000 |
| Grant date | May 6, 2003 |
| Priority date | — |
| Expiry date | May 16, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/2441
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The present invention comprises a tool for and a method of inspecting a mask used in photolithography to determine errors in phase, amplitude, and pattern edges. An embodiment of the tool comprises a laser source, a polarizing beam splitter, a first shutter, a mask, a second shutter, a quarter wave retarder, a single-mode optical fiber, and a CCD detector array. An embodiment of the method comprises four independent measurements of light intensity, comprising: a pattern of a mask, a diffraction pattern of a reference pinhole, an interference pattern of the mask and the reference pinhole, and an interference pattern of the mask and the reference pinhole with a known phase difference. Calculations are performed to determine phase and amplitude information as a function of location on the mask. The phase and amplitude information is then compared with a design layout of the mask to determine pattern edge information and identify possible defects in the mask.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.