Method to diagnose imperfections in illuminator of a lithographic tool
US6943882B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 19, 2002 |
| Grant date | Sep 13, 2005 |
| Priority date | — |
| Expiry date | Feb 23, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70133
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method for diagnosing a lithographic tool. The method includes developing digitalized images of at least one wafer pattern with different exposure doses and assembling the digitized images into a pupilgram. The at least one function is of a known illuminator behavior of the lithographic tool is modeled. The pupilgram is fitted to the modeled function to determine whether a behavior associated with the pupilgram is within predetermined limits of illuminator behavior to diagnosis imperfections in the illuminator behavior. One technique applied to the illuminator analysis consists of evaluating the dose transmitted (by direct calculation) by the lens for a given input pupilgram (or set of pupilgram basis functions), a given pattern size and pitch, and a defined lens NA, is described. This transmitted dose is calculated and displayed as a function of position within the illumination distribution (pupilgram), and is valuable for the highlighting of those parts of the illumination distribution that contribute the largest amount of relative dose to the imaging process, and to compare the dose transmitted by different orientations of the same pattern.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.