Transparent photographic masks

Abstract

Abstract Photographic masks, suitable for reproduction in a photoresist layer -- by exposure of the latter to actinic light under the mask, and development of the photo-resist image -- of the pattern of a microelectronic component or device, are made by exposure to light in accordance with an original (especially by contact exposure under a primary mask) containing the pattern to be reproduced, of light-sensitive material having a flat, rigid, dimensionally stable transparent base such as glass and a thin (e.g. 0.5 to 10 micron thick) transparent resin layer adhering to the base and containing, molecularly dispersed therein an azo coupling component and a light-sensitive diazonium compound, susceptible to decomposition on exposure to light and temporarily stabilized against coupling pending alkaline development, the diazonium compound and coupling component being uniformly distributed throughout the thickness of the resin layer, said light-sensitive material yielding on development with ammonia vapor, in the unexposed areas, an azo dye coloration transparent to visible light but opaque to ultraviolet light, while the decomposition products of the diazonium compound and azo coupling component in the light-exposed areas are transparent to ultraviolet as well as visible light. The light-sensitive materials are made by applying the sensitizing composition and resin to the base in the form of a solution in a volatile solvent, removing any excess e.g. by centrifugation, and drying to remove the solvent. The masks produced afford satisfactory resolution to 0.1 micron. They are used to reproduce the pattern in a photo-resist layer coated on a substrate such as a silicon wafer, as by contact exposure under the mask, development of the photo-resist, and suitable modifying treatment of the thereby exposed areas of the underlying substrate.

Inventors

• 👤 Frank J. Loprest

Bibliographic Details