Kill index analysis for automatic defect classification in semiconductor wafers

Abstract

A kill index classification method for prioritizing relational aspects of topological defect intersections, particularly in association with an intermediate analytical testing stage of a multi-stage semiconductor fabrication process. The method relates to an analysis of the geometrical relationship between non-predetermined portion(s), generally referred to as defects, and the surrounding predetermined topology of a conductive semiconductor pattern, to determine the effect of defects on the functionality and reliability of a wafer, and particularly an examined die thereon. Further, in accordance with this geometrical information, a preferred classification of the effects of defects into a numerical value, the “kill index”, is achieved. Preferably, this kill index is strongly linked, correlated and related to the damage caused by the defect to the functionality and/or reliability of the underlying integrated circuit.

What is claimed is:  
     
         1 . In a semiconductor fabrication process, a kill index classification method for prioritizing relational aspects of topological defect intersections, said method including the steps of 
 a) locating a region having at least one non-predetermined portion therein;    b) determining a predetermined topology for the region;    c) calculating evaluation parameters based on the at least one non-predetermined portion in relation to the predetermined topology for the region; and    d) assigning a kill index classification using the calculated evaluation parameters.    
     
     
         2 . The kill index classification method according to  claim 1  wherein the step of locating a region having at least one non-predetermined portion therein includes the steps of 
 a1) accepting at least one appropriate resolution image of the region; and  
 a2) using the at least one appropriate resolution image, analyzing the region to determine if there is a rule violating shaped portion located therein.  
 
     
     
         3 . The kill index classification method according to  claim 2   wherein the step of accepting at least one appropriate resolution image of the region includes the steps of 
 i) accepting a reference image, and  
 ii) accepting a defect image, and  
   wherein the step of analyzing the region to determine if there is a rule violating shaped portion located therein includes the step of comparing the reference image with the defect image.    
     
     
         4 . The kill index classification method according to  claim 2   wherein the step of accepting at least one appropriate resolution image of the region includes the steps of 
 i) accepting a reference map, and  
 ii) accepting a defect image, and  
   wherein the step of analyzing the region to determine is there is a rule violating shaped portion located therein includes the step of comparing the reference map with the defect image.    
     
     
         5 . The kill index classification method according to  claim 2   wherein the step of accepting at least one appropriate resolution image of the region includes the steps of 
 i) accepting a reference rule set, and  
 ii) accepting a defect image; and  
   wherein the step of analyzing the region to determine if there is a rule violating shaped portion located therein includes the step of comparing the reference rule set with the defect image.    
     
     
         6 . The kill index classification method according to  claim 5  wherein the reference rule set includes a threshold for at least one topological feature selected from the list of 
 i) a detected edge discontinuity,  
 ii) a detected edge curvature,  
 iii) an interior angle formed from two intersecting detected edges,  
 iv) an exterior angle formed from two intersecting detected edges, or  
 v) a fabrication mask topology design principle.  
 
     
     
         7 . The kill index classification method according to  claim 1  wherein the step of determining a predetermined topology for the region includes at least one step selected from the list of 
 i) examining a reference image;,  
 ii) examining a reference map; or  
 iii) examining a fabrication mask topology design algorithm methodology used to produce the reference map.  
 
     
     
         8 . The kill index classification method according to  claim 1  wherein the step of calculating evaluation parameters based on the at least one non-predetermined portion in relation to the predetermined topology for the region includes the step of assigning a topology intersection parameter for the juxtaposition of the at least one non-predetermined portion with the predetermined topology.  
     
     
         9 . The kill index classification method according to  claim 1  wherein the step of assigning a kill index classification using the calculated evaluation parameters includes convoluting the calculated evaluation parameters into a numeric classification.  
     
     
         10 . The kill index classification method according to  claim 1  wherein the step of assigning a kill index classification using the calculated evaluation parameters includes convoluting the calculated evaluation parameters into a multi-parametric classification coordinate.  
     
     
         11 . The kill index classification method according to  claim 1  wherein the step of locating a region having at least one non-predetermined portion therein includes locating a region having at least one defect footprint.  
     
     
         12 . The kill index classification method according to  claim 11  wherein locating a region having at least one defect footprint includes locating a region having at least one multi-component footprint.  
     
     
         13 . The kill index classification method according to  claim 1  wherein the step of calculating evaluation parameters based on the at least one non-predetermined portion in relation to the predetermined topology for the region includes said at least one non-predetermined portion having at least one non-predetermined portion core class selected from the list: 
 a) at least one pattern non-predetermined portion selected from the list: 
 i) extra pattern connected,  
 ii) extra pattern isolated,  
 iii) missing pattern, and  
 iv) deformed pattern; or  
 
 b) at least one non-predetermined particle portion selected from the list: 
 i) crater in pattern,  
 ii) crater in background,  
 iii) particle on pattern,  
 iv) particle on background,  
 v) particle on distortion,  
 vi) embedded under pattern, and  
 vii) embedded under background.  
 
 
     
     
         14 . The kill index classification method according to  claim 1  wherein the step of calculating evaluation parameters based on the at least one non-predetermined portion in relation to the predetermined topology for the region includes said evaluation parameters having at least one parameter selected from the list: 
 a) a non-predetermined portion isolated from the predetermined topology;  
 b) a non-predetermined portion close to the predetermined topology;  
 c) a non-predetermined portion connected to the predetermined topology;  
 d) a non-predetermined portion bridging the predetermined topology; and  
 e) a non-predetermined portion close to bridging the predetermined topology.  
 
     
     
         15 . The kill index classification method according to  claim 14  wherein said non-predetermined portion isolated from the predetermined topology includes a distance greater than a predetermined distance between the at least one non-predetermined portion and a pattern portion of the predetermined topology.  
     
     
         16 . The kill index classification method according to  claim 14  wherein said non-predetermined portion close to the predetermined topology includes a distance less than a predetermined distance between the at least one non-predetermined portion and a pattern portion of the predetermined topology.  
     
     
         17 . The kill index classification method according to  claim 14  wherein said non-predetermined portion connected to the predetermined topology includes the at least one non-predetermined portion being in contact with a pattern portion of the predetermined topology.  
     
     
         18 . The kill index classification method according to  claim 14  wherein said non-predetermined portion bridging the predetermined topology includes at least one parameter selected from the list: 
 a) at least one non-predetermined portion connecting at least two pattern portions of the predetermined topology;  
 b) at least one non-predetermined portion connecting at least one pattern portion and intersecting at least one other pattern portion of the predetermined topology; and  
 c) at least one non-predetermined portion intersecting at least two pattern portions of the predetermined topology.  
 
     
     
         19 . The kill index classification method according to  claim 14  wherein said non-predetermined portion close to bridging the predetermined topology includes the at least one non-predetermined portion being close to at least two pattern portions of the predetermined topology.  
     
     
         20 . A computer program product including a computer usable medium having computer readable program code embodied therein for a kill index classification method for prioritizing relational aspects of topological defect intersections in a semiconductor fabrication process, the computer readable program code in said computer usable medium including at least one program code selected from: 
 a) first computer readable program code for causing a computer to locate a region having at least one non-predetermined portion therein;    b) tied to the first computer readable program code, second computer readable program code for causing the computer to determine a predetermined topology for the region;    c) tied to the second computer readable program code, third computer readable program code for causing the computer to calculate evaluation parameters based on the at least one non-predetermined portion in relation to the predetermined topology for the region; and    d) tied to the third computer readable program code, fourth computer readable program code for causing the computer to assign a kill index classification using the calculated evaluation parameters;    wherein the kill index classification method includes the steps of    a) locating a region having at least one non-predetermined portion therein;    b) determining a predetermined topology for the region;    c) calculating evaluation parameters based on the at least one non-predetermined portion in relation to the predetermined topology for the region; and    d) assigning a kill index classification using the calculated evaluation parameters.    
     
     
         21 . A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform a kill index classification method for prioritizing relational aspects of topological defect intersections in a semiconductor fabrication process, said method including the steps of: 
 a) locating a region having at least one non-predetermined portion therein;    b) determining a predetermined topology for the region;    c) calculating evaluation parameters based on the at least one non-predetermined portion in relation to the predetermined topology for the region; and    d) assigning a kill index classification using the calculated evaluation parameters.    
     
     
         22 . Apparatus for performing a kill index classification method for prioritizing relational aspects of topological defect intersections in a semiconductor fabrication process, wherein said apparatus includes: 
 a) a locator module for locating a region having at least one non-predetermined portion therein;    b) in communication with the locator module, a determiner module for determining a predetermined topology for the region;    c) in communication with the determiner module, a calculator module for calculating evaluation parameters based on the at least one non-predetermined portion in relation to the predetermined topology for the region; and    d) in communication with the calculator module, an assignor module for assigning a kill index classification using the calculated evaluation parameters.    
     
     
         23 . A system for operating a multi-stage semiconductor fabrication process in association with at least two intermediate analytical testing stages, wherein, at each stage, a kill index classification method is performed for prioritizing relational aspects of topological defect intersections, wherein said system includes a management module for operating said multi-stage semiconductor fabrication process, and wherein, in association with the management module, there are at least two apparatus for using a kill index classification method for prioritizing relational aspects of topological defect intersections, and each said apparatus includes: 
 a) a locator module for locating a region having at least one non-predetermined portion therein;    b) in communication with the locator module, a determiner module for determining a predetermined topology for the region;    c) in communication with the determiner module, a calculator module for calculating evaluation parameters based on the at least one non-predetermined portion in relation to the predetermined topology for the region; and    d) in communication with the calculator module, an assignor module for assigning a kill index classification using the calculated evaluation parameters.    
     
     
         24 . A method according to  claim 1 , wherein said semiconductor fabrication process is a multi-stage semiconductor fabrication process, and wherein said kill index classification method is performed after each stage of said multi-stage semiconductor fabrication process.  
     
     
         25 . A method according to  claim 20 , wherein said semiconductor fabrication process is a multi-stage semiconductor fabrication process, and wherein said kill index classification method is performed after each stage of said multi-stage semiconductor fabrication process.  
     
     
         26 . A method according to  claim 21 , wherein said semiconductor fabrication process is a multi-stage semiconductor fabrication process, and wherein said kill index classification method is performed after each stage of said multi-stage semiconductor fabrication process.  
     
     
         27 . A method according to  claim 22 , wherein said semiconductor fabrication process is a multi-stage semiconductor fabrication process, and wherein said kill index classification method is performed after each stage of said multi-stage semiconductor fabrication process.