Evaluating the quality of an assist feature placement based on a focus-sensitive cost-covariance field
US8296688B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 26, 2011 |
| Grant date | Oct 23, 2012 |
| Priority date | — |
| Expiry date | Apr 26, 2031 |
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. 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.