Assist features for use in lithographic projection
US6887625B2 · kind B2 · utility
14Cited by
3References
62Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jul 16, 2001 |
| Grant date | May 3, 2005 |
| Priority date | — |
| Expiry date | Apr 9, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F1/36
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
In a mask pattern for a device such as a DRAM including a nearly regular array of isolated features, assist features are positioned so as to make the array more symmetric. Where the isolated features are positioned at most but not all of the points of a regular unit cell, the assist features may be positioned at the points of the unit cell not occupied by the isolated features. The isolated features may represent contact holes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.