Alignment method usable in a step-and-repeat type exposure apparatus for either global or dye-by-dye alignment
US4918320A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 18, 1988 |
| Grant date | Apr 17, 1990 |
| Priority date | — |
| Expiry date | Mar 18, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7003
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method of aligning a semiconductor wafer, usable in a step-and-repeat type exposure apparatus for projecting, in a reduced scale, images of a pattern formed on a reticle upon different shot areas on the semiconductor wafer in a predetermined sequence. According to this alignment method, the wafer is moved stepwise before the initiation of step-and-repeat exposures of the shot areas on the wafer and in accordance with a predetermined layout grid concerning the sites of the shot areas on the wafer. While moving the wafer stepwise in this manner, any positional deviation of each of some of the shot areas with respect to the layout grid is measured by use of a reduction projection lens system and, from the results of measurement, a corrected grid is prepared according to which grid the amount of stepwise movement of the wafer to be made for the step-and-repeat exposures thereof is determined. By this, for the exposures, the wafer can be moved stepwise exactly in accordance with the actual layout of the shot areas. Sample shot areas which are the subject of measurement can be selected under predetermined conditions. Additionally, of the values obtained as a result of the measurement, …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.