Lithographic mask, comprising a membrane having improved strength
US5362575A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 31, 1992 |
| Grant date | Nov 8, 1994 |
| Priority date | — |
| Expiry date | Dec 31, 2012 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/24926
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A membrane is supported at its edge by an annular, tapered skirt structure. The skirt strengthens the attachment of the membrane to the support ring and reinforces the edge region where the membrane would otherwise tend to fail. Stress concentrations are reduced by providing a skirt or featheredge, on the interior side of the skirt, that meets the membrane at a relatively small effective contact angle. In a preferred embodiment, the membrane is made by depositing a polysilicon layer on the surface of a substrate of silica-based glass. A portion of the substrate is removed by an isotropic, selective etchant, such that a portion of the polysilicon layer remains as a free-standing, tensile film supported by a remaining portion of the substrate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.