Method for evaluating the effects of multiple exposure processes in lithography
US6777147B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | May 21, 2003 |
| Grant date | Aug 17, 2004 |
| Priority date | — |
| Expiry date | May 21, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70641
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method of evaluating process effects of multiple exposure photolithographic processes by first determining a set of expected images for each exposure step or process of the multiple exposure process individually and then obtaining a composite set of images by sequentially perturbing images from a first or previous exposure step by weighted images from the subsequent exposure step. Preferably, the expected images are determined by simulation in the form of normalized aerial images over a range of defocus for each exposure step, and the weighting factor used is the dose-ratio of the subsequent exposure dose to the prior step exposure dose. The resulting composite set of images may be used to evaluate multiple exposure processes, for example, to provide an estimate of yield for a given budget of dose and focus errors, or alternatively, to provide specifications for tool error budgets required to obtain a target yield.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.