Apparatus for measuring grain sizes in metalized layers
AssigneeTherma-Wave, Inc.
InventorsJon Opsal, Allan Rosencwaig
Life of this patent
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Abstract
An apparatus (10) is disclosed for evaluating the size of grains in a metalized layer on a semiconductor sample (12). The apparatus includes a laser (20) for generating a probe beam (22). The probe beam is focused to a diameter of about one micron and scanned over the surface of the sample. Variations in the power of the specularly reflected beam are measured. In one aspect of the subject invention, the spacing between minima in the reflectivity signal is used to give a direct measurement of average grain size. The depth of the minima can be used to derive a distribution of the grain size. For very small grains, a statistical evaluation of the reflectivity signal is performed to derive grain size.
Claims16
An apparatus for evaluating grain sizes on the surface of the sample, wherein the grains have irregular shapes, said apparatus comprising:
- means for generating a probe beam;
- means for scanning the probe beam with respect to the surface of the sample an amount sufficient to cross a plurality of grain boundaries;
- means for measuring the power of the reflected probe beam as a function of the position of the probe beam on the surface of the sample;
- and
- processor means for evaluating the sizes of the grains on the sample surface based on the probe beam power measurements, said processor means functioning to determine the average distance on the sample between locations where the power measurement drops below a predetermined threshold level to derive the average grain size.
An apparatus for evaluating the distribution of grain sizes on the surface of the sample, wherein the grains have irregular shapes comprising:
- means for generating a probe beam;
- means for scanning the probe beam with respect to the surface of the sample an amount sufficient to cross a plurality of grain boundaries;
- means for measuring the power of the reflected probe beam as a function of the position of the probe beam on the surface of the sample;
- and
- processor means for evaluating the distribution of grain size on the sample surface based on a determination of the number of times the minima of the probe beam power measurements fall below a predetermined threshold level in combination with a determination of the depth of these minima.
An apparatus for evaluating grain sizes on the surface of the sample, wherein the grains have irregular shapes, said apparatus comprising:
- means for generating a probe beam;
- means for focusing the probe beam onto the surface of the sample to diameter on the order of one micron;
- means for scanning the probe beam with respect to the surface of the sample an amount sufficient to cross a plurality of grain boundaries;
- means for measuring the power of the reflected probe beam as a function of the position of the probe beam on the surface of the sample;
- and
- processor means for evaluating the average size of the grains on the sample surface based on a statistical analysis of the variations in the probe beam power measurements.
A method for evaluating grain sizes on the surface of the sample, wherein the grains have irregular shapes, said method comprising the steps of:
- generating a probe beam;
- scanning the probe beam with respect to the surface of the sample an amount sufficient to cross a plurality of grain boundaries;
- measuring the power of the reflected probe beam as a function of the position of the probe beam on the surface of the sample;
- and
- evaluating the sizes of the grains on the sample surface based on the probe beam power measurements by determining the average distance on the sample between locations where the power measurement drops below a predetermined threshold level to derive the average grain size.
A method for evaluating the distribution of grain sizes on the surface of the sample, wherein the grains have irregular shapes, said method comprising the steps of:
- generating a probe beam;
- scanning the probe beam with respect to the surface of the sample an amount sufficient to cross a plurality of grain boundaries;
- measuring the power of the reflected probe beam as a function of the position of the probe beam on the surface of the sample;
- and
- evaluating the distribution of grain size on the sample surface based on a determination of the number of times the minima of the probe beam power measurements fall below a predetermined threshold level in combination with a determination of the depth of these minima.
A method for evaluating grain sizes on the surface of the sample, wherein the grains have irregular shapes, said method comprising:
- generating a probe beam;
- focusing the probe beam onto the surface of the sample to diameter on the order of one micron;
- scanning the probe beam with respect to the surface of the sample an amount sufficient to cross a plurality of grain boundaries;
- measuring the power of the reflected probe beam as a function of the position of the probe beam on the surface of the sample;
- and
- evaluating the average size of the grains on the sample surface based on a statistical analysis of the variations in the probe beam power measurements.
Dependencies are inferred from the claim text.