Process and assembly for non-destructive surface inspection

7) An optical system for detecting defects on a wafer that includes at least one pattern;

• the system comprising:
• a source of light to produce a beam;
• optics directing the beam along a path onto the wafer surface, producing an illuminated spot thereon;
• an array of detectors detecting light;
• an ellipsoidal mirrored surface, said mirrored surface and the array of detectors having an axis of symmetry about a line perpendicular to the wafer, said mirrored surface defining an input aperture positioned proximate to the test surface to receive scattered light therethrough from the surface;
• said mirrored surface further defining an exit aperture and being substantially rotationally symmetric about said axis of symmetry, so that the mirrored surface reflects and focuses rotationally symmetrically about said axis of symmetry light that passes through the input aperture to the array of detectors;
• said exit aperture being located between said array of detectors and said input aperture;
• said array of detectors are adapted to detect scattered light substantially other than scattered light part being scattered from at least one of said patterns.

14) An optical system for detecting defects on a wafer that includes at least one pattern;

• the system comprising:
• a source of light to produce a beam;
• optics directing the beam along a path onto the wafer, producing an illuminated spot thereon;
• at least one detector for detecting light;
• an ellipsoidal mirrored surface, said mirrored surface and the at least one detector having an axis of symmetry about a line perpendicular to the wafer surface, said mirrored surface defining an input aperture positioned proximate to the wafer surface to receive scattered light therethrough from the surface;
• said mirrored surface further defining an exit aperture and being substantially rotationally symmetric about said axis of symmetry, so that the mirrored surface reflects and focuses rotationally symmetrically about said axis of symmetry light that passes through said input aperture to the at least one detector;
• said exit aperture being located opposite to the input aperture;
• a Dove prism, having with the at least one detector an axis of symmetry about a line perpendicular to the wafer's surface and parallel to said Dove prism's base, said Dove prism being rotated about said axis of symmetry, so as to rotate light passing through said Dove prism at twice the angular velocity of said Dove prism in the opposite direction about said axis of symmetry;
• and
• at least one filter located between said Dove prism and said at least one detector and being configured to pass to said at least one detector scattered light rays substantially other than scattered light part being scattered from at least one of said patterns.

17) An optical system for detecting defects on a wafer that includes at least one pattern;

• the system comprising:
• a source of light to produce a beam;
• optics directing the beam along a path onto the wafer, producing an illuminated spot thereon;
• an array of detectors for detecting light;
• an ellipsoidal mirrored surface, said mirrored surface and the array of detectors having an axis of symmetry about a line perpendicular to the wafer surface, said mirrored surface defining an input aperture positioned proximate to the wafer surface to receive scattered light therethrough from the surface;
• said mirrored surface further defining an exit aperture and being substantially rotationally symmetric about said axis of symmetry, so that said mirrored surface reflects and focuses rotationally symmetrically about said axis of symmetry light that passes through said input aperture to the array of detectors;
• said exit aperture being located opposite to said input aperture;
• a Dove prism, said Dove prism and the array of detectors having an axis of symmetry about a line perpendicular to the wafer surface and parallel to said Dove prism's base, said Dove prism being rotated about said axis of symmetry, so as to rotate light passing through said Dove prism at twice the angular velocity of said Dove prism in the opposite direction about said axis of symmetry;
• said Dove prism further being configured to pass to said array of detectors scattered light rays substantially other than scattered light part being scattered from at least one of said patterns.

20) An optical system for detecting defects on a wafer that includes at least one pattern;

• the system comprising:
• a source of light to produce a beam;
• means for directing the beam along a path onto the wafer, producing an illuminated spot thereon;
• at least one means for detecting light;
• an ellipsoidal mirrored surface, said mirrored surface and the at least one detecting means having an axis of symmetry about a line perpendicular to the wafer surface, said mirrored surface defining an input aperture positioned proximate to the wafer surface to receive scattered light therethrough from the surface;
• said mirrored surface further defining an exit aperture and being substantially rotationally symmetric about said axis of symmetry, so that the mirrored surface reflects and focuses rotationally symmetrically about said axis of symmetry light that passes through the input aperture to the at least one detecting means;
• said exit aperture being located opposite to the input aperture;
• and
• at least one filter located between said exit aperture and said at least one detecting means and being configured to pass to said at least one detecting means scattered light rays substantially other than scattered light part being scattered from at least one of said patterns.

21) An optical system for detecting defects on a wafer that includes at least one pattern;

• the system comprising:
• a source of light to produce a beam;
• means for directing the beam along a path onto the wafer surface, producing an illuminated spot thereon;
• an array of detecting means for detecting light;
• an ellipsoidal mirrored surface, said mirrored surface and the array of detecting means having an axis of symmetry about a line perpendicular to the wafer, said mirrored surface defining an input aperture positioned proximate to the test surface to receive scattered light therethrough from the surface;
• said mirrored surface further defining an exit aperture and being substantially rotationally symmetric about said axis of symmetry, so that the mirrored surface reflects and focuses rotationally symmetrically about said axis of symmetry light that passes through the input aperture to the array of detecting means;
• said exit aperture being located between said array of detecting means and said input aperture;
• said array of detecting means are adapted to detect scattered light substantially other than scattered light part being scattered from at least one of said patterns.

22) An optical system for detecting defects on a wafer, comprising:

• a device for producing a beam and directing the beam onto the wafer surface, so as to produce an illuminated spot thereon;
• at least one detector detecting light;
• a mirrored assembly having together with the at least one detector an axis of symmetry about a line perpendicular to the wafer surface, said assembly is configured to receive scattered light from the surface;
• said assembly further configured to reflect and focus rotationally symmetrically about said axis of symmetry the scattered light to the at least one detector;
• and
• a device associated with said at least one detector for facilitating detection of a scattered light substantially other than scattered light part being scattered from at least one of said patterns.

24) An optical system for detecting defects on a wafer, comprising:

• a device for producing a beam and directing the beam onto the wafer surface, so as to produce an illuminated spot thereon;
• at least one detector detecting light;
• a mirrored assembly configured to receive scattered light from the surface;
• said assembly further configured to reflect the scattered light to the at least one detector;
• and
• a device associated with said at least one detector for facilitating detection of a scattered light substantially other than scattered light part being scattered from at least one of said patterns.

26) An optical method for detecting defects on a wafer that includes at least one pattern;

• the method comprising:
• providing a beam of light;
• directing the beam along a path onto the wafer, producing an illuminated spot thereon;
• positioning an ellipsoidal mirrored surface and at least one detector so that they have an axis of symmetry about a line perpendicular to the wafer surface, said mirrored surface defining an input aperture positioned proximate to the wafer surface to receive scattered light therethrough from the surface;
• said mirrored surface further defining an exit aperture and being substantially rotationally symmetric about said axis of symmetry, so that the mirrored surface reflects and focuses rotationally symmetrically about said axis of symmetry light that passes through the input aperture to the at least one detector;
• said exit aperture being located opposite to the input aperture;
• and
• locating at least one filter between said exit aperture and said at least one detector, configuring the at least one filter to pass to said at least one detector scattered light rays substantially other than scattered light part being scattered from at least one of said patterns.

27) An optical method for detecting defects on a wafer that includes at least one pattern;

• the method comprising:
• providing a beam of light;
• directing the beam along a path onto the wafer surface, producing an illuminated spot thereon;
• positioning an ellipsoidal mirrored surface and an array of detectors so that hey have an axis of symmetry about a line perpendicular to the wafer, said mirrored surface defining an input aperture positioned proximate to the test surface to receive scattered light therethrough from the surface;
• said mirrored surface further defining an exit aperture and being substantially rotationally symmetric about said axis of symmetry, so that the mirrored surface reflects and focuses rotationally symmetrically about said axis of symmetry light that passes through the input aperture to the array of detectors;
• said exit aperture being located between said array of detectors and said input aperture;
• adapting said array of detectors to detect scattered light substantially other than scattered light part being scattered from at least one of said patterns.

28) An optical method for detecting defects on a wafer that includes at least one pattern;

• the method comprising:
• providing a beam of light;
• directing the beam along a path onto the wafer, producing an illuminated spot thereon;
• positioning an ellipsoidal mirrored surface and at least one detector so that they have an axis of symmetry about a line perpendicular to the wafer surface, said mirrored surface defining an input aperture positioned proximate to the wafer surface to receive scattered light therethrough from the surface;
• said mirrored surface further defining an exit aperture and being substantially rotationally symmetric about said axis of symmetry, so that the mirrored surface reflects and focuses rotationally symmetrically about said axis of symmetry light that passes through said input aperture to the at least one detector;
• said exit aperture being located opposite to the input aperture;
• positioning a Dove prism, so as to have with the at least one detector an axis of symmetry about a line perpendicular to the wafer's surface and parallel to said Dove prism's base;
• said Dove prism is rotated about said axis of symmetry, so as to rotate light passing through said Dove prism at twice the angular velocity of said Dove prism in the opposite direction about said axis of symmetry;
• and
• locating at least one filter between said Dove prism and said at least one detector and configuring the filter to pass to said at least one detector scattered light rays substantially other than scattered light part being scattered from at least one of said patterns.

29) An optical method for detecting defects on a wafer that includes at least one pattern;

• the method comprising:
• providing a beam of light;
• directing the beam along a path onto the wafer, producing an illuminated spot thereon;
• positioning an ellipsoidal mirrored surface and an array of detectors so that they have an axis of symmetry about a line perpendicular to the wafer surface, said mirrored surface defining an input aperture positioned proximate to the wafer surface to receive scattered light therethrough from the surface;
• said mirrored surface further defining an exit aperture and being substantially rotationally symmetric about said axis of symmetry, so that said mirrored surface reflects and focuses rotationally symmetrically about said axis of symmetry light that passes through said input aperture to the array of detectors;
• said exit aperture being located opposite to said input aperture;
• positioning a Dove prism so as to have with the array of detectors an axis of symmetry about a line perpendicular to the wafer surface and parallel to said Dove prism's base;
• said Dove prism is rotated about said axis of symmetry, so as to rotate light passing through said Dove prism at twice the angular velocity of said Dove prism in the opposite direction about said axis of symmetry;
• said Dove prism is further being configured to pass to said array of detectors scattered light rays substantially other than scattered light part being scattered from at least one of said patterns.

30) An optical method for detecting defects on a wafer, comprising:

• providing a device for producing a beam and directing the beam onto the wafer surface so as to produce illuminated spot thereon;
• positioning a mirrored assembly and at least one detector so that they have an axis of symmetry about a line perpendicular to the wafer surface;
• configuring said assembly to receive scattered light from the surface and further configuring said assembly to reflect and focus rotationally symmetrically about said axis of symmetry the scattered light to the at least one detector;
• and
• positioning a device associated with said at least one detector for facilitating detection of a scattered light substantially other than scattered light part being scattered from at least one of said patterns.

31) An optical method for detecting defects on a wafer, comprising:

• providing a device for producing a beam and directing the beam onto the wafer surface so as to produce an illuminated spot thereon;
• positioning a mirrored assembly configured to receive scattered light from the surface and further configuring said assembly to reflect the scattered light to the at least one detector;
• and
• positioning a device associated with said at least one detector for facilitating detection of a scattered light substantially other than scattered light part being scattered from at least one of said patterns.