System for providing photomask alignment keys in semiconductor integrated circuit processing
US4343878A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 2, 1981 |
| Grant date | Aug 10, 1982 |
| Priority date | — |
| Expiry date | Jan 2, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/00
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A system for providing photomask alignment keys in semiconductor integrated circuit processing involving selecting a common photomask subarea to be utilized as an alignment key pattern area on each photomask in the set with the alignment key pattern area having an array of sequential key locations. Each photomask after the first has a designated alignment key location which is either the same alignment key location as the immediately preceding photomask or the next alignment key location in the array. A mask key pattern is formed on the first photomask comprising aligning keys for all the associated higher numbered photomasks designed to be aligned to topography created by use of the first photomask in accordance with a mask alignment formula with each of the aligning keys being formed at key locations corresponding to the designated alignment key locations for the associated photomask. On each of the remaining photomasks of the set a mask key pattern is formed comprising an alignment key at the designated alignment key location and aligning keys for any associated higher numbered ones of the photomasks designed in accordance with the mask alignment formula to be aligned to the top…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.