Graded anti-reflective coatings for photolithography
US6379014B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 27, 2000 |
| Grant date | Apr 30, 2002 |
| Priority date | — |
| Expiry date | Apr 27, 2020 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/12653
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A graded anti-reflective coating (ARC) with one or more layers has a bottom layer that is highly absorbing at the lithographic wavelength, and one or more layers between the substrate and the resist layer having inhomogeneous optical constants. The refractive indices are matched across layer interfaces, and the optical constants vary smoothly through the layer thicknesses. In each layer the extinction coefficient and the refractive index have independently selectable values and gradients. This ARC structure provides almost total absorption in the bottom layer and near-zero reflection at the resist interface and all other intermediate interfaces. Layers are preferably of inorganic materials, typically SiOxNy. Because of its highly absorbing bottom layer, an ARC according to an embodiment of the present invention works effectively over diverse substrate materials for a variety of lithographic wavelengths. It provides great latitude of manufacturing tolerances for thicknesses and optical constants.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.