System and method for defect detection threshold determination in an workpiece surface inspection system

A system for inspecting a surface of a semiconductor workpiece, the system comprising:

• a laser source that causes a laser light to impinge upon a test location on the workpiece surface and thereby cause the laser light to emerge from the surface as returned light comprising at least one of reflected light and scatter light;
• a collection subsystem that collects the returned light and generates a signal from the returned and collected light, the signal comprising a signal value representative of a characteristic of the workpiece surface at the test location;
• a processing device that compares the signal value to a plurality of threshold candidates and selects a threshold from among the plurality of threshold candidates, and that uses the threshold to assess the characteristic of the workpiece surface at the test location;
• wherein the surface inspection system to automatically analyzes the workpiece surface at a plurality of test locations by making said comparisons at each of the test locations.

A method of differentiating noise from particles on a surface of a semiconductor workpiece using a threshold, wherein the threshold is used to assess a characteristic of the workpiece surface at a current test location, the method comprising:

• providing a surface inspection system and using the surface inspection apparatus to cause laser light to impinge upon the current test location on the workpiece surface and thereby cause the laser light to emerge from the surface as returned light comprising at least one of reflected light and scatter light;
• collecting the returned light and generating a signal from the returned and collected light, the signal comprising a signal value representative of the characteristic of the workpiece surface at the current test location and a plurality of prior signal values representative of the characteristic of the workpiece surface at a corresponding plurality of secondary test locations, wherein the secondary test locations comprise at least one of the current test location and test locations other than the current test location;
• causing the surface inspection system to select a threshold from among at least one threshold candidate, wherein the at least one threshold candidate is selected based on statistical data for the secondary test locations;
• comparing the threshold to the signal value to obtain a difference value;
• using the difference value to assess the characteristic of the workpiece surface at the current test location;
• and
• using the surface inspection system to automatically cause the method to be repeated for a plurality of test locations on the workpiece surface.

A system for inspecting a surface of a semiconductor workpiece, wherein the workpiece surface has a characteristic at a current test location, the system comprising:

• a laser source that causes a laser light to impinge upon the current test location on the workpiece surface and thereby cause the laser light to emerge from the surface as returned light comprising at least one of reflected light and scatter light;
• a collection subsystem that collects the returned light and generates a signal from the returned and collected light, the signal comprising a signal value representative of the characteristic of the workpiece surface at the current test location and a plurality of prior signal values representative of the characteristic of the workpiece surface at a corresponding plurality of secondary test locations, wherein the secondary test locations comprise at least one of the current test location and test locations other than the current test location;
• and
• a processing device that selects a threshold from among at least one threshold candidate, compares the threshold to the signal value to obtain a difference value, and uses the difference value to assess the characteristic of the workpiece surface at the current test location, wherein the at least one threshold candidate is selected based on statistical data for the secondary test locations;
• wherein the surface inspection system automatically analyzes the workpiece surface at a plurality of test locations on the workpiece surface by making said comparisons at each of the test locations.

A method for inspecting a surface of a semiconductor workpiece, the method comprising:

• providing a surface inspection system and using the surface inspection apparatus to cause laser light to impinge upon a test location on the workpiece surface and thereby cause the laser light to emerge from the surface as returned light comprising at least one of reflected light and scatter light;
• collecting the returned light and generating a signal from the returned and collected light, the signal comprising a signal value representative of a characteristic of the workpiece surface at the test location, wherein the signal value comprises raw data comprising a data line comprising a vector of voltage values based on intensity measurements of the returned light at locations on the workpiece surface within the test location and a selected scan line;
• filtering the raw data;
• extracting components of the signal value representative of the matched filtered
• data and attributable to a haze component and a noise component;
• performing a thresholding calculation;
• and
• using the surface inspection system to automatically cause the method to be repeated for a plurality of test locations on the workpiece surface.

A method for inspecting a surface of a semiconductor workpiece, the method comprising:

• providing a surface inspection system and using the surface inspection apparatus to cause laser light to impinge upon a test location on the workpiece surface and thereby cause the laser light to emerge from the surface as returned light comprising at least one of reflected light and scatter light;
• collecting the returned light and generating a signal from the returned and collected light, the signal comprising a signal value representative of a characteristic of the workpiece surface at the test location;
• providing a plurality of threshold candidates in respective tiers and causing the surface inspection system to select a threshold from among the plurality of threshold candidates using the tiers;
• comparing the threshold to the signal value to obtain a difference value;
• using the difference value to assess the characteristic of the workpiece surface at the test location;
• and
• using the surface inspection system to automatically cause the method to be repeated for a plurality of test locations on the workpiece surface.