Method to form code marks on mask ROM products
US6623911B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 17, 2001 |
| Grant date | Sep 23, 2003 |
| Priority date | — |
| Expiry date | Nov 11, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L2924/0002
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A method for forming a clear code mark that is independent of backend planarization by adding an extra exposing step to the normal photolithography process is described. A layer to be patterned is provided on a substrate. A photoresist layer is coated overlying the layer to be patterned. The photoresist layer is first exposed through a code mask and second exposed through a patterning mask. The photoresist layer is developed to form a photoresist mask having a code mark pattern from the code mask and a device pattern from the patterning mask. The layer to be patterned is etched away where it is not covered by the photoresist mask to form simultaneously device structures and a code mark in the fabrication of an integrated circuit device.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.