Laser imaging system for inspection and analysis of sub-micron particles

A microscope for imaging a surface of an object, the microscope comprising:

• a stage for supporting the object;
• a laser imaging system configured to provide a three-dimensional image of the surface, the laser imaging system including:
• a laser light source for emitting a beam of laser light;
• a lens arranged to be between the laser light source and the stage, the lens having a focal plane;
• a beam scanner for scanning the beam and for directing the scanned beam toward the stage through the lens;
• and
• a first photodetector for measuring the intensity of laser light reflected from the surface of the object, wherein the measured intensity of laser light reflected from the surface is at a maximum intensity when the surface lies in the focal plane of the lens;
• and
• a white-light imaging system for imaging the surface simultaneous with the laser imaging system, the white-light imaging system including:
• a white light source for emitting white light toward the stage;
• and
• a second photodetector for measuring the intensity of white light reflected from the surface.

A microscope for imaging a surface of an object, the microscope comprising:

• a stage for supporting the object;
• a laser imaging system for imaging the surface, the laser imaging system including:
• a laser light source for emitting a beam of laser light;
• a lens arranged to be between the laser light source and the stage, the lens having a focal plane;
• a beam scanner for scanning the beam and for directing the scanned beam toward the stage through the lens;
• and
• a first photodetector for measuring the intensity of laser light reflected from the surface of the object, wherein the measured intensity of laser light reflected from the surface is at a maximum intensity when the surface lies in the focal plane of the lens;
• and
• a white-light imaging system for imaging the surface simultaneous with the laser imaging system, the white-light imaging system including:
• a white light source for emitting white light toward the stage;
• and
• a second photodetector for measuring the intensity of white light reflected from the surface;
• wherein one of the laser light or the white light is to be emitted at a first wavelength for causing fluorescence of a particular material in or on the surface such that the one of the laser light or white light is reflected from the material at a second wavelength, and
• wherein the microscope further comprises a filter for allowing light of the second wavelength to pass through the filter and for preventing light of the first wavelength from passing through the filter.

An imaging system for detection or analysis of defects in or on an object to be imaged, the system comprising:

• a stage for supporting the object;
• a source of polarized light of a first polarity, the source for directing polarized light toward the stage, whereby the polarized light impinges upon the object when the object is supported by the stage;
• a pinhole aperture positioned between the light source and the stage such that a portion of the light of a first polarity travels through the pinhole aperture toward the stage;
• a lens, mounted between the source of polarized light and the stage, for focusing the portion of the light of the first polarity to a focal point of the lens;
• a photodetector for measuring the intensity of light reflected from the object when the object is supported by the stage, wherein the intensity of light reflected from the object is at a maximum intensity when a surface of the object and the focal point are coincident;
• and
• a filter, positioned between the stage and the photodetector, for changing the polarization of reflected light so that the polarization of light reflected by the surface is of a second polarity different from the first polarity.

A system for inspecting a semiconductor wafer to determine the efficacy of a wafer process previously performed, the system comprising:

• a stage for supporting the wafer to be inspected;
• a light source for emitting a beam of light;
• a beam scanner for scanning the beam and directing the scanned beam toward the stage, wherein the stage is arranged such that a portion of the scanned beam will be reflected from a plurality of points on a surface of the wafer to be inspected;
• a photodetector for measuring the intensity of the reflected portion of the scanned beam from the plurality of points on the wafer surface to define a plurality of test values, each of the test values representing the intensity of light reflected from one of the plurality of points on the wafer surface;
• a first region of memory for storing the plurality of test values;
• a second region of memory for storing a plurality of reference values, each of the reference values representing the intensity of light reflected from one of a plurality of points on a reference surface;
• and
• means for comparing ones of the plurality of test values with corresponding ones of the plurality of reference values to identify differences between corresponding ones of the test and reference values,
• wherein the differences between corresponding ones of the test and reference values diagnose whether an optical anomaly is present on the wafer and
• wherein the optical anomaly provides an indication of the efficacy of the process.

A system for inspecting a semiconductor wafer to determine the efficacy of a wafer process previously performed, the system comprising:

• a stage for supporting the wafer to be inspected;
• a light source for emitting a beam of light;
• a beam scanner for scanning the beam and directing the scanned beam toward the stage, wherein the stage is arranged such that a portion of the scanned beam will be reflected from a plurality of points on a surface of the wafer to be inspected;
• a photodetector for measuring the intensity of the reflected portion of the scanned beam from the plurality of points on the wafer surface to define a plurality of test values, each of the test values representing the intensity of light reflected from one of the plurality of points on the wafer surface;
• a first region of memory for storing the plurality of test values;
• a second region of memory for storing a plurality of reference values, each of the reference values representing the intensity of light reflected from one of a plurality of points on a reference surface;
• and
• means for comparing ones of the plurality of test values with corresponding ones of the plurality of reference values to identify differences between corresponding ones of the test and reference values,
• wherein the differences between corresponding ones of the test and reference values indicate the presence of an optical anomaly, and
• wherein the optical anomaly provides an indication of the efficacy of the process,
• said system further comprising a third region of memory for storing a group of difference values, the group of difference values representing the differences between corresponding test and reference values, and
• wherein the means for comparing may be used to analyze the group of difference values to determine a location of the anomaly on the wafer, the location being defined by X, Y, and Z coordinates.

A system for inspecting a semiconductor wafer to determine the efficacy of a wafer process previously performed, the system comprising:

• a stage for supporting the wafer to be inspected;
• a laser light source for emitting a beam of light, wherein the laser light source is capable of emitting light of a plurality of wavelengths;
• a beam scanner for scanning the beam and directing the scanned beam toward the stage, wherein the stage is arranged such that a portion of the scanned beam will be reflected from a plurality of points on a surface of the wafer to be inspected;
• a photodetector for measuring the intensity of the reflected portion of the scanned beam from the plurality of points on the wafer surface to define a plurality of test values, each of the test values representing the intensity of light reflected from one of the plurality of points on the wafer surface;
• a first region of memory for storing the plurality of test values;
• a second region of memory for storing a plurality of reference values, each of the reference values representing the intensity of light reflected from one of a plurality of points on a reference surface;
• and
• means for comparing ones of the plurality of test values with corresponding ones of the plurality of reference values to identify differences between corresponding ones of the test and reference values,
• wherein the differences between corresponding ones of the test and reference values indicate the presence of an optical anomaly, and
• wherein the optical anomaly provides an indication of the efficacy of the process.

A method of locating an optical anomaly on a test surface, wherein the test surface is contained within a test volume represented by a Cartesian coordinate system having x, y, and z axes describing a set of unique x-y-z coordinates, the method comprising the steps of:

• scanning the test surface in the test volume with a focussed beam so that the focal point of the focussed beam coincides, in turn, with each unique x-y-z coordinate within the test volume;
• determining, for each unique x-y-z coordinate in the test volume, a reflected intensity of the focussed beam to create a set of reflected intensity values;
• and
• comparing the set of reflected intensity values to a set of reference values to determine whether the set of reflected intensity values is different from the set of reference values;
• wherein differences between the set of reflected intensity values and the set of reference values indicate the presence of an optical anomaly.

A method comprising the steps of:

• generating three-dimensional microscope image data representing a semiconductor wafer;
• comparing the three-dimensional microscope image data to reference three-dimensional image data;
• and
• characterizing structures on the semiconductor wafer based on the step of comparing.

A system for inspecting a semiconductor wafer to determine the efficacy of a wafer process previously performed, the system comprising:

• means for supporting the wafer to be inspected;
• means for emitting a beam of light;
• means for scanning the beam and directing the scanned beam toward the stage, wherein the stage is arranged such that a portion of the scanned beam will be reflected from a plurality of points on a surface of the wafer to be inspected;
• means for measuring the intensity of the reflected portion of the scanned beam from the plurality of points on the wafer surface to define a plurality of test values, each of the test values representing the intensity of light reflected from one of the plurality of points on the wafer surface;
• a first memory means for storing the plurality of test values;
• a second memory means for storing a plurality of reference values, each of the reference values representing the intensity of light reflected from one of a plurality of points on the wafer surface;
• and
• means for comparing ones of the plurality of test values with corresponding ones of the plurality of reference values to identify differences between corresponding ones of the test and reference values,
• wherein the differences between corresponding ones of the test and reference values diagnose whether an optical anomaly is present on the wafer, and
• wherein the optical anomaly provides an indication of the efficacy of the process.

A system for inspecting a semiconductor wafer to determine the efficacy of a wafer process previously performed, the system comprising:

• means for supporting the wafer to be inspected;
• means for emitting a beam of light;
• means for scanning the beam and directing the scanned beam toward the stage, wherein the stage is arranged such that a portion of the scanned beam will be reflected from a plurality of points on a surface of the wafer to be inspected;
• means for measuring the intensity of the reflected portion of the scanned beam from the plurality of points on the wafer surface to define a plurality of test values, each of the test values representing the intensity of light reflected from one of the plurality of points on the wafer surface;
• a first memory means for storing the plurality of test values;
• a second memory means for storing a plurality of reference values, each of the reference values representing the intensity of light reflected from one of a plurality of points on the wafer surface;
• and
• means for comparing ones of the plurality of test values with corresponding ones of the plurality of reference values to identify differences between corresponding ones of the test and reference values,
• wherein the differences between corresponding ones of the test and reference values indicate the presence of an optical anomaly, and
• wherein the optical anomaly provides an indication of the efficacy of the process,
• said system further comprising a third memory means for storing a group of difference values, the group of difference values representing the differences between corresponding test and reference values;
• and
• wherein the means for comparing may be used to analyze the group of difference values to determine a location of the anomaly on the wafer, the location being defined by X, Y, and Z coordinates.

A system for inspecting a semiconductor wafer to determine the efficacy of a wafer process previously performed, the system comprising:

• means for supporting the wafer to be inspected;
• a laser capable of emitting light of a plurality of wavelengths;
• means for scanning the beam and directing the scanned beam toward the stage, wherein the stage is arranged such that a portion of the scanned beam will be reflected from a plurality of points on a surface of the wafer to be inspected;
• means for measuring the intensity of the reflected portion of the scanned beam from the plurality of points on the wafer surface to define a plurality of test values, each of the test values representing the intensity of light reflected from one of the plurality of points on the wafer surface;
• a first memory means for storing the plurality of test values;
• a second memory means for storing a plurality of reference values, each of the reference values representing the intensity of light reflected from one of a plurality of points on a reference surface;
• and
• means for comparing ones of the plurality of test values with corresponding ones of the plurality of reference values to identify differences between corresponding ones of the test and reference values,
• wherein the differences between corresponding ones of the test and reference values indicate the presence of an optical anomaly, and
• wherein the optical anomaly provides an indication of the efficacy of the process.

A method comprising the steps of:

• generating three-dimensional microscope image data representing a workpiece bearing an integrated circuit pattern;
• comparing the three-dimensional microscope image data to reference three-dimensional image data;
• and
• characterizing structures on the workpiece based on the step of comparing.