Combination thin-film stress and thickness measurement device
OwnerLanhua Weiinventor
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Abstract
A composite metrology tool, measures basic optical parameters of thin films (e.g., thickness, index of refraction, and birefringence) and stress (e.g., wafer displacements, such as bow and warp). These measurements are combined (e.g. in a processor) using optimization techniques to yield accurate overall information of the wafer parameters.
Claims41
A method of analyzing a wafer having a thin film thereon, comprising:
- obtaining at least one optical property measurement of the thin film that is nominally indicative of the thickness of the thin film;
- measuring a deformation of the thin film that is nominally indicative of an amount of stress on the thin film;
- and
- combining the at least one optical property measurement with the deformation measurement to determine the thickness of the thin film and the stress on the thin film.
The method of claim 2, wherein the combining step utilizes an optimization algorithm.
A method of analyzing the characteristics of a thin film on a semiconductor wafer comprising the steps of:
- directing a first probe beam of radiation to reflect off the wafer surface;
- measuring the change in magnitude or polarization of the reflected probe beam induced by the interaction with the wafer and generating first signals responsive thereto;
- directing a second probe beam of radiation to reflect of the wafer;
- measuring the angular deviation of the reflected probe induced by the interaction with the wafer and generating second signals responsive thereto;
- analyzing the first and second signals in order to determine characteristics of the wafer including the thickness of the film and the stress in the film.
A method of measuring parameters of a substantially planar wafer, comprising:
- supporting the wafer only at points substantially two-thirds of the distance from the center of the wafer;
- directing a probe beam of radiation onto the wafer;
- and
- determining at least one parameter based on an observation of the interaction of the probe beam with the wafer.
A method of calibrating a wafer tilt detection system for use in correcting a measured tilt of a wafer resting on a movable stage, comprising:
- resting a spherical mirror on the stage in place of the wafer;
- directing the probe beam to the spherical mirror;
- moving the stage and, at a plurality of positions of the stage, determining the angle between the probe beam and the reflection of the probe beam;
- and
- determining a relationship between the positions and the determined angles, whereby the relationship is a tilt detection system calibration factor by which an actual tilt measurement of the wafer may be adjusted.
A method of determining a stage tilt calibration factor for use in correcting a measured tilt of a wafer resting on a movable stage, comprising:
- resting a flat mirror on the stage in place of the wafer;
- directing the probe beam to the flat mirror;
- moving the stage and, at a plurality of positions of the stage, determining the angle between the probe beam and the reflection of the probe beam;
- and
- determining a relationship between the positions and the determined angles, whereby the relationship is the stage tilt calibration factor.
An apparatus for analyzing a wafer having a thin film thereon, comprising:
- a first light generator that directs a first probe beam of radiation to reflect off the wafer surface;
- an analyzer that measures the change in magnitude or polarization of the reflected probe beam induced by the interaction with the wafer and generates first signals responsive thereto;
- a second light generator that directs a second probe beam of radiation to reflect of the wafer;
- a detector that detects the angular deviation of the reflected probe induced by the interaction with the wafer and generates second signals responsive thereto,
- wherein the first light generator, the analyzer, the second light generator and the detector are provided in a single tool.
Dependencies are inferred from the claim text.