Method and system for machine vision-based feature detection and mark verification in a workpiece or wafer marking system

Abstract

A system and method for inspecting machine readable marks on one side of a wafer without requiring transmission of radiant energy from another side of the wafer and through the wafer. The wafer has articles which may include die, chip scale packages, circuit patterns and the like. The marking occurs in a wafer marking system and within a designated region relative to an article position. The articles have a pattern on a first side. The method includes the steps of imaging a first side of the wafer, imaging a second side of the wafer, establishing correspondence between a portion of first side image and a portion of a second side image, and superimposing image data from the first and second sides to determine at least the position of a mark relative to an article.

1. A method for inspecting machine readable marks on one side of a wafer without requiring transmission of radiant energy from another side of the wafer and through the wafer, the wafer having articles which may include die, chip scale packages, circuit patterns and the like, the marking occuring in a wafer marking system and within a designated region relative to an article position, the articles having a pattern on a first side, the method comprising:
 imaging a first side of the wafer;  
 imaging a second side of the wafer;  
 establishing correspondence between a portion of first side image and a portion of a second side image; and  
 superimposing image data from the first and second sides to determine at least the position of a mark relative to an article.  
 
     
     
       2. The method of  claim 1  further comprising substantially matching images obtained from the first and second sides so that the superimposed image portions correspond, wherein the step of substantially matching is carried out using a calibration target and a matching algorithm. 
     
     
       3. The method of  claim 2  wherein the superimposed data is used to determine the position of a mark relative to the article. 
     
     
       4. A system for inspecting machine readable marks on one side of a wafer without requiring transmission of radiant energy from another side of the wafer and through the wafer, the wafer having articles which may include die, chip scale packages, circuit patterns and the like, the marking occurring in a wafer marking system and within a designated region relative to an article position, the articles having a pattern on a first side, the system comprising:
 means for imaging the first side of the wafer to obtain an image;  
 means for imaging a mark on the second side of the wafer to obtain an image;  
 means for establishing correspondence between a portion of a first side image and a portion of a second side image; and  
 means for superimposing image data from the first and second sides to determine at least the position of the mark relative to an article.  
 
     
     
       5. The system as claimed in  claim 4  wherein the means for establishing correspondence includes a calibration target and an algorithm.