Automated specimen inspection system for and method of distinguishing features or anomalies under either bright field or dark field illumination

An automated method of inspection of a surface of a specimen having distinguishing features or anomalies that are detectable under either bright field illumination or dark field illumination, comprising:

• directing light rays from one or more light sources of line illumination, each of which in optical association with a corresponding line aperture, to strike the surface of the specimen at angles of incidence that provide simultaneous bright field and dark field illumination of the specimen, the light rays directed to strike the surface of the specimen illuminating first and second spaced-apart scan areas of the specimen;
• imparting to the specimen and the light rays relative motion that causes the light rays to traverse the surface of the specimen and that leaves substantially unchanged the angles of incidence at which the light rays strike the surface;
• collecting at least some of the light rays after they have struck the surface of the specimen, the collected light rays including bright field light rays propagating along a bright field path and dark field light rays propagating along a dark field path, and the collecting of light rays being accomplished by positioning a first set of multiple light path directing elements to receive and direct along a first path the bright field light rays and positioning a second set of multiple light path directing elements to receive and direct along a second path the dark field light rays, the first set of light path directing elements being positioned to receive bright field light rays propagating from the first scan area and the second set of light path directing elements being positioned to receive dark field light rays propagating from the second scan area;
• and
• processing the bright field light rays to detect features or anomalies having characteristic signatures under bright field illumination and processing the dark field light rays to detect dark field features or anomalies having characteristic signatures under dark field illumination to thereby merge bright field and dark field specimen feature or anomaly information.

An automated method of inspection of a surface of a specimen having a surface area and distinguishing features or anomalies that are detectable under either bright field illumination or dark field illumination, comprising:

• directing light rays from one or more light sources of line illumination, each of which in optical association with a corresponding line aperture, to strike the surface of the specimen at angles of incidence that provide simultaneous bright field and dark field illumination of the specimen, the light rays directed to strike the surface of the specimen propagating from multiple stationary light sources of line illumination and the multiple stationary light sources of line illumination being positioned to illuminate first and second stationary spaced-apart elongate scan areas of the specimen;
• imparting to the specimen and the light rays relative motion that causes the light rays to traverse the surface of the specimen and that leaves substantially unchanged the angles of incidence at which the light rays strike the surface, the specimen being mounted to a linear translation table that moves the specimen relative to the light sources of line illumination to cause the light rays to traverse the surface of the specimen, the table moving the specimen so that the first and second scan areas scan the entire surface area of the specimen;
• collecting at least some of the light rays after they have struck the surface of the specimen, the collected light rays including bright field light rays propagating along a bright field path and dark field light rays propagating along a dark field path;
• and
• processing the bright field light rays to detect features or anomalies having characteristic signatures under bright field illumination and processing the dark field light rays to detect dark field features or anomalies having characteristic signatures under dark field illumination to thereby merge bright field and dark field specimen feature or anomaly information.

An automated method of inspection of a surface of a specimen having distinguishing features or anomalies that are detectable under dark field illumination, comprising:

• supporting the specimen in place on a support member;
• providing an illumination system from which light rays propagate to strike the surface of the specimen at angles of incidence that provide dark field illumination of a scan area of the specimen, the illumination system having an effective illumination surface and the scan area having a width, the effective illumination surface being substantially larger than the scan area so that the light rays striking the scan area provide illumination of substantially uniform intensity across the width of the scan area;
• imparting relative motion to the support member on which the specimen is supported in place and the light rays, the relative motion causing the light rays to traverse the surface of the specimen and leaving substantially unchanged the angles of incidence at which light rays strike the surface;
• collecting at least some of the light rays after they have struck the surface of the specimen, the collected light rays including dark field light rays propagating along the dark field path;
• and
• processing the dark field light rays to detect specimen features or anomalies having characteristic signatures under dark field illumination.

A specimen inspection system for detecting a distinguishing feature or anomaly, comprising:

• a specimen support including a table for holding in place a specimen under inspection having a surface;
• an illumination system from which light rays propagate, the illumination system having an effective illumination surface and being positioned relative to the surface of the specimen so that light rays strike the surface of the specimen at angles of incidence that provide dark field illumination of a scan area of the specimen, the effective illumination surface being substantially larger than the scan area so that the light rays striking the scan area have no appreciable difference in light intensity or light intensity distribution angle;
• a mechanism for imparting to the table holding the specimen in place and illumination system relative motion that causes the light rays to traverse the surface of the specimen and that leaves substantially unchanged the angles of incidence at which the light rays strike the surface;
• a light collecting system for collecting dark field light rays propagating from the scan area as the light rays traverse the surface of the specimen;
• and
• a processor for determining from the dark field light rays the presence of a specimen feature or anomaly having a characteristic signature under dark field illumination.

An automated method of inspection of a surface of a specimen having distinguishing features or anomalies that are detectable under either bright field illumination or dark field illumination, comprising:

• supporting the specimen in place on a support member;
• directing light rays from one or more light sources of line illumination, each of which in optical association with a corresponding line aperture, to strike the surface of the specimen at angles of incidence that provide simultaneous bright field and dark field illumination of the specimen, and at least one of the light sources comprises multiple light emitters in optical association with a light diffusing element;
• imparting relative motion to the support member on which the specimen is supported in place and the light rays, the relative motion causing the light rays to traverse the surface of the specimen and leaving substantially unchanged the angles of incidence at which the light rays strike the surface;
• collecting at least some of the light rays after they have struck the surface of the specimen, the collected light rays including bright field light rays propagating along a bright field path and dark field light rays propagating along a dark field path;
• and
• processing the bright field light rays to detect features or anomalies having characteristic signatures under bright field illumination and processing the dark field light rays to detect dark field features or anomalies having characteristic signatures under dark field illumination to thereby merge bright field and dark field specimen feature or anomaly information.

An automated method of inspection of a surface of a specimen having distinguishing features or anomalies that are detectable under either bright field illumination or dark field illumination, comprising:

• supporting the specimen in place on a support member;
• directing light rays to strike the surface of the specimen at angles of incidence that provide simultaneous bright field and dark field illumination of the specimen;
• imparting relative motion to the support member on which the specimen is supported in place and the light rays, the relative motion causing the light rays to traverse the surface of the specimen and leaving substantially unchanged the angles of incidence at which the light rays strike the surface;
• collecting at least some of the light rays after they have struck the surface of the specimen, the collected light rays including bright field light rays propagating along a bright field path and dark field light rays propagating along a dark field path;
• and
• processing the bright field light rays to detect features or anomalies having characteristic signatures under bright field illumination and processing the dark field light rays to detect dark field features or anomalies having characteristic signatures under dark field illumination to thereby merge bright field and dark field specimen feature or anomaly information, the processing including comparing the bright field and dark field specimen feature or anomaly information against a pre-established detection level stored in a database.

An automated method of inspection of a surface of a specimen having distinguishing features or anomalies that are detectable under either bright field illumination or dark field illumination, comprising:

• supporting the specimen in place on a support member;
• directing light rays to strike the surface of the specimen at angles of incidence that provide simultaneous bright field and dark field illumination of the specimen, the surface having a surface area and the light rays striking a region of the surface area;
• imparting relative motion to the support member on which the specimen is supported in place and the light rays, the relative motion causing the light rays to traverse the surface of the specimen, a quantity of the light rays striking the region of the surface area forming a scan area that is substantially smaller than the region of the surface area so that the angles of incidence of the quantity of the light rays are about the same, and the relative motion leaving substantially unchanged the angles of incidence at which the quantity of the light rays forming the scan area strike the surface;
• collecting at least some of the quantity of the light rays after they have struck the scan area of the surface of the specimen, the collected light rays including bright field light rays propagating along a bright field path and dark field light rays propagating along a dark field path;
• and
• processing the bright field light rays to detect features or anomalies having characteristic signatures under bright field illumination and processing the dark field light rays to detect dark field features or anomalies having characteristic signatures under dark field illumination to thereby merge bright field and dark field specimen feature or anomaly information.

An automated method of inspection of a surface of a specimen that includes multiple reticle fields having repeatable pattern features across the multiple reticle fields, the specimen having distinguishing features or anomalies that are detectable under either bright field illumination or dark field illumination, comprising:

• directing light rays to strike the surface of the specimen at angles of incidence that provide simultaneous bright field and dark field illumination of the specimen;
• imparting to the specimen and the light rays relative motion that causes the light rays to traverse the surface of the specimen and that leaves substantially unchanged the angles of incidence at which the light rays strike the surface;
• collecting at least some of the light rays after they have struck the surface of the specimen, the collected light rays including bright field light rays propagating along a bright field path and dark field light rays propagating along a dark field path;
• and
• processing the bright field light rays to detect features or anomalies having characteristic signatures under bright field illumination and processing the dark field light rays to detect dark field features or anomalies having characteristic signatures under dark field illumination to thereby merge bright field and dark field specimen feature or anomaly information, the processing including comparing the bright field and dark field specimen feature or anomaly information against a pre-established detection level stored in a database by computing an image difference between two of the reticle fields and forming from the image difference a gray level deviation map for comparison against a gray level standard.

An automated method of inspection of a surface of a specimen having distinguishing features or anomalies that are detectable under either bright field illumination or dark field illumination, comprising:

• directing light rays to strike the surface of the specimen at angles of incidence that provide simultaneous bright field and dark field illumination of the specimen, the surface having a surface area and the light rays striking a region of the surface area;
• imparting to the specimen and the light rays relative motion that causes the light rays to traverse the surface of the specimen, a quantity of the light rays striking the region of the surface area forming a scan area that is substantially smaller than the region of the surface area so that the angles of incidence of the quantity of the light rays are about the same, and the relative motion leaving substantially unchanged the angles of incidence at which the quantity of the light rays forming the scan area strike the surface;
• collecting at least some of the quantity of the light rays after they have struck the scan area of the surface of the specimen, the collected light rays including bright field light rays propagating along a bright field path and striking a first light sensitive sensor and dark field light rays propagating along a dark field path and striking a second light sensitive sensor;
• and
• processing the bright field light rays to detect features or anomalies having characteristic signatures under bright field illumination and processing the dark field light rays to detect dark field features or anomalies having characteristic signatures under dark field illumination to thereby merge bright field and dark field specimen feature or anomaly information.