Method and system for machine vision-based feature detection and mark verification in a workpiece or wafer marking system
A precision laser based method of marking semiconductor wafers, packages, substrates or similar workpieces is provided. The workpieces have articles which may include die, chip scale packages, circuit patterns and the like. The marking occurs in a workpiece marking system and within a designated region relative to an article position. The method includes determining at least one location from which reference data is to be obtained using (a) information from which a location of an article is defined, and (b) a vision model of at least a portion of at least one article. Reference data is obtained to locate a feature on a first side of (a second) workpiece using at least one signal from a first sensor. The method further includes positioning a marking field relative to the workpiece so as to position a laser beam at a marking location on a second side of the workpiece. The positioning is based on the feature location. A predetermined pattern is marked on the second side of the workpiece using a laser marking output beam. The workpiece is a semiconductor wafer, and the step of determining includes: measuring at least one feature in an image obtained from a first wafer portion; relating the measured feature to a wafer map; and storing the data for use when marking of wafers substantially identical to the first wafer.
1 - 24 . (canceled)
25 . 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, marking of the marks 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 of the wafer, the method comprising:
imaging at least a portion of the first side of the wafer to obtain a first side image;
imaging at least a portion of a second side of the wafer to obtain a second side image;
establishing a correspondence between at least a portion of the first side image and at least a portion of the second side image;
determining at least the position of a mark relative to an article based on the correspondence.
26 . The method of claim 25 further comprising:
receiving a wafer map that provides information for marking an article and information that relates to coordinates of die within a pattern;
relating image information from the first or second side images so as to provide relative coordinate information, the image information being related to the position of the article and mark position relative to the article; and
storing the relative coordinate information for use when marking or inspecting at least one of a portion of the wafer and a portion of other substantially identical wafers.
27 . The method of claim 25 , wherein the step of imaging at least a portion of the first side further includes: generating a vision model of the at least one portion of the first side wherein the vision model is the first side image obtained during the steps of establishing a correspondence and determining.
28 . The method of claim 25 , wherein coordinates of the mark is the position of the mark.
29 . The method of claim 25 , wherein the step of establishing is carried out with a calibration target and a matching algorithm.
30 . 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, marking of the marks 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 of the wafer, the system comprising:
means for imaging at least a portion of the first side of the wafer to obtain a first side image;
means for imaging at least a portion of a second side of the wafer to obtain a second side image;
means for establishing a correspondence between at least a portion of the first side image and at least a portion of the second side image;
means for determining at least the position of a mark relative to an article based on the correspondence.
31 . The system as claimed in claim 30 , wherein the means for establishing includes a calibration target and a matching algorithm.