Optics: measuring and testing – By alignment in lateral direction – With registration indicia
Patent
1992-12-31
1994-06-28
Evans, F. L.
Optics: measuring and testing
By alignment in lateral direction
With registration indicia
2504431, 2504911, G01B 1100
Patent
active
053251806
ABSTRACT:
The present invention provides a device which can identify and measure both thermally induced errors and system induced errors in a measuring system, especially a photolithographic system for processing semiconductor wafers. The system includes a stage having associated therewith a first material having a known, relatively high, coefficient of thermal expansion (CTE) and a second material having a significantly lower (preferably zero) CTE in the temperature range in which the system is to be used. The system has a "home" position or location. At least one first indicia mark or set of marks is placed on the first material at a given known (calibrated) distance(s) (at a given known temperature) from the "home" position, and at least one second indicia mark or set of marks is placed on the second material at a given known (calibrated) distance(s) from the home position. The system is configured to periodically measure (even during wafer processing) the distances between each of the indicia marks and the "home" position. By periodically measuring these distances and checking them against their calibrated values, the system can determine, measure and distinguish both system induced errors and temperature induced errors.
REFERENCES:
patent: 5031331 (1991-07-01), Herzog et al.
Patent Abstracts of Japan, Abstract Group No. E151, vol. 7, No. 4, Publication date Jan. 8, 1983, Abstract of 57-162431.
Chappelow Ronald E.
Conrad Edward W.
Evans F. L.
International Business Machines - Corporation
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