Mask having multiple patterns

US5439764A · kind A · utility

Assignee

• Micrel, Inc. · US

Inventors

• Martin Alter · Los Altos, US
• Lawrence R. Sample · Tecate Mission Road, US
• Hiu Ip · San Jose, US
• Marty Garnett · Los Gatos, US
• Helmuth R. Litfin · San Jose, US

Key dates

• Filing date: Jul 1, 1993
• Grant date: Aug 8, 1995
• Expiry date: Jul 1, 2013

Classification

• Technology area (CPC G): Physics
• CPC primary: G03F1/50
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

One embodiment of the invention includes multiple patterns on a single mask, where all the patterns on the single mask are used for forming a single product. In the preferred embodiment, each of four quadrants of a mask have a different process layer pattern, where each of the four patterns is associated with a different process layer for the same product. After exposure of the wafer using the mask, the mask is rotated 90.degree. for the next exposure step so that the mask pattern image for the next layer to be formed on the wafer will overlie the designated quadrant of the wafer which will contain the final product. Although, by using this technique, three-quarters of the wafer will be unusable, this partial waste of the wafer will be offset by the savings in mask costs with low volume production, in prototyping situations, and in product debugging. Using the above technique, conventional mask exposure machines may be used.