Overlying shifter type phase shift photomask blank, overlying shifter type phase shift photomask and methods of producing them
US5576123A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 16, 1995 |
| Grant date | Nov 19, 1996 |
| Priority date | — |
| Expiry date | Mar 16, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P70/50
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An overlying shifter type phase shift photomask used to produce semiconductor integrated circuits of high integration density, e.g. VLSI, ULSI, etc., which is capable of transferring fine-line patterns to a wafer by projection exposure. The photomask is produced by forming at least a light-blocking layer pattern or a combination of a light-blocking layer pattern and an etching stopper layer for a shifter layer on a transparent substrate, forming a shifter layer over the whole surface of the substrate, and then patterning the shifter layer to form a shifter layer pattern. The production method includes the step of polishing away unevenness on the surface of the shifter layer caused by a step which is produced by the light-blocking layer pattern, thereby leveling the surface of the shifter layer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.