Determining the gradient and hessian of the image log slope for design rule optimization for accelerating source mask optimization (SMO)
US8356261B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Jul 2, 2010 |
| Grant date | Jan 15, 2013 |
| Priority date | — |
| Expiry date | Nov 23, 2030 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F1/70
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The Hessian (second derivative) of the image log slope (ILS) can be quickly and accurately calculated without the need to use approximate methods from the gradient of the ILS with respect to mask transmission and source intensity. The Hessian has been traditionally calculated using a finite-difference approach. Calculating the Hessian through a finite-difference approach is slow and is an approximate method. The gradient of the ILS improves the speed of calculation of the Hessian, and thus accelerated SMO operation is realized. The results of ILS evaluation can be used in design for manufacturing (DFM) to suggest changes in the design rules to improve imaging. For a fixed illumination, this information can help remove forbidden pitches and help select design rules for 1-D and 2-D patterns on a mask design layout.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.