Integrated circuit system with automated best focus determination based on change in alignment due to predictable pattern degradation
US6542221B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 28, 2000 |
| Grant date | Apr 1, 2003 |
| Priority date | — |
| Expiry date | Jan 23, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70641
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method (40) of determining a best focus for an integrated circuit stepper (10). The method repeats various steps for a plurality of different focus levels. The repeated steps include forming a first element group (C1) on a wafer (30F1), where the first element group comprises one or more elements and each of the one or more elements in the first element group has a shape. The repeated steps further include defining a first reference point (CC1) for the first element group at a position relative to the shape of the one or more elements in the first element group. Similarly, the repeated steps include forming a second element group (C2) on the wafer, where the second group comprises one or more elements and each of the one or more elements in the second element group has a shape, and defining a second reference point (CC2) for the second element group at a position relative to the shape of the one or more elements in the second element group. Still another repeated step is measuring a distance between the first reference point and the second reference point such that a distance measurement is identified for each of the plurality of different focus levels. Finally, the method select…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.