Exposure control for phase shifting photolithographic masks
US7422841B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 7, 2004 |
| Grant date | Sep 9, 2008 |
| Priority date | — |
| Expiry date | May 7, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70558
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Mask and integrated circuit fabrication approaches are described to facilitate use of masks where substantially all of a layout is defined using phase shifting. Exposure settings including relative dosing between the phase shift mask and the trim masks are described. Additionally, single reticle approaches for accommodating both masks are considered. In one embodiment, the phase shifting mask and the trim mask are exposed using the same exposure conditions that have an effect on the characteristics of the radiation used for the exposure, except for relative dosing. The same exposure conditions are changeable optical parameters that consist of numerical aperture (N.A.), wavelength (λ) of radiation, partial coherency (σ), illumination configuration, and defocus. These approaches facilitate better exposure profiles for the resulting ICs and can thus improve chip yield and increase throughput by reducing the need to alter settings and/or switch reticles between exposures.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.