Assist feature placement based on a focus-sensitive cost-covariance field
US7954071B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 31, 2008 |
| Grant date | May 31, 2011 |
| Priority date | — |
| Expiry date | Oct 20, 2029 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70641
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
One embodiment of the present invention provides a system that determines an assist feature placement within a post-optical proximity correction (post-OPC) mask layout. During operation, the system receives a set of target patterns which represent a set of polygons in a pre-OPC mask layout. The system then constructs a focus-sensitive cost function based on the target patterns, wherein the focus-sensitive cost function represents an amount of movement of post-OPC contours of the target patterns in response to changes in focus condition of the lithography system. Note that the contours of the target patterns substantially coincide with the edges of set of the polygons. Next, the system computes a cost-covariance field (CCF field) based on the focus-sensitive cost function, wherein the CCF field is a two-dimensional (2D) map representing changes to the focus-sensitive cost function due to an addition of a pattern at a given location within the post-OPC mask layout. Finally, the system generates assist features for the post-OPC mask layout based on the CCF field.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.