Apparatus and methods for reducing tool-induced shift during overlay metrology
US7433039B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 6, 2004 |
| Grant date | Oct 7, 2008 |
| Priority date | — |
| Expiry date | Oct 14, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70616
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Disclosed are apparatus and methods for determining a minimum tool-induced shift (TIS) during an overlay metrology procedure. In a specific embodiment, a method of determining overlay or misalignment error on a target is disclosed. For a predefined number of positions of a target within a field of view (FOV) of a metrology tool, the following operations are performed: (i) determining a tool-induced shift (TIS) parameter value for each predefined position of the target within the FOV based on at least one overlay measurement obtained from the target at the each position (for example, based on overlay measurements at 0 and 180 degrees of wafer orientation) and (ii) determining a minimum TIS parameter value and its corresponding FOV position from the plurality of determined TIS parameters values at the predefined positions of the target within the FOV. The FOV position that corresponds to the minimum TIS is then defined as an appropriate position for the actual overlay measurement and the value of minimum TIS is used for overlay correction.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.