Apparatus and method for curvature and thin film stress measurement
AssigneeHermes-Epitek Corporation
InventorsChung-Yuan WU, Robert Champetier, Chung-Hua FU, Bu-Chin CHUNG
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Abstract
Apparatus and method for curvature and thin film stress measurement are disclosed. The apparatus comprises two light sources and a detector. Two light beams from the two light sources with an angle are not parallel. The two light beams are collimated and projected onto a specimen with a pitch. The detector receives the light beams reflected from the specimen. The curvature of the specimen is calculated via a distance between spots of the light beams on the detector or a size variation of one of the spots.
Claims22
An apparatus for curvature and thin film stress measurement, comprising:
- a first light source and a second light source, the second light source and the first light source being located such that an angle is formed between a second light beam from the second light source and a first light beam from the first light source;
- a first collimator and a second collimator, the first light beam and the second light beam projecting on a specimen after being approximately collimated by the first collimator and the second collimator, such that the first light beam and the second light beam are brought to a sharp focus on the detector, after reflection from the specimen;
- a beam splitter being configured to be located between the first collimator and the second collimator and the specimen;
- and
- a detector, the beam splitter reflecting the first light beam and the second light beam reflected from the specimen to the detector, wherein the spots of the first and second light beams on the detector overlap if the specimen is flat.
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An apparatus for curvature and thin film stress measurement, comprising:
- two light sources being located such that an angle is formed between two light beams from the light sources respectively, the light beams being focused sharply at the detector, after first reflecting from a specimen, wherein a distance is between locations of the light beams on the specimen;
- and
- a detector, the detector receiving the light beams reflected from the specimen and calculating a curvature of the specimen according to a separation between spots of the light beams on the detector, wherein the spots of the light beams on the detector overlap if the specimen is for calibration.
A method for curvature and thin film stress measurement, comprising:
- providing two non-parallel focused light beams with an angle therebetween;
- projecting the light beams onto a specimen, wherein a distance is between locations of the light beams on the specimen;
- receiving the light beams reflected from the surface of the specimen;
- and
- calculating a curvature of the specimen according to a displacement between focused spots of the light beams on a detector, wherein the spots of the light beams on the detector overlap if the specimen is flat.
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Dependencies are inferred from the claim text.