Extended kalman filter incorporating offline metrology

Abstract

An algorithm uses offline metrology to control a process by passing information from an outer control loop to an inner control loop, extended Kalman filter estimator. The inner control loop operates online, and the outer control loop operates asynchronously with respect to the inner control loop. The online control loop is updated for each subsequent process. The offline metrology is optionally updated for each subsequent process.

1 . A computer readable medium for executing a set of instructions, the computer readable medium comprising: 
 in an inner loop: 
 establishing estimates of state variables of a substrate planarizing cycle, wherein establishing includes the use of an extended Kalman filter engine; and  
 estimating the endpoint of the substrate planarizing cycle based upon the estimates of the state variables;  
   in an outer loop: 
 asynchronously comparing at least one of a state variable and an endpoint to an offline metrology database; and  
 sending and information statement from the outer loop to the inner loop.  
   
   
   
       2 . The computer readable medium according to  claim 1 , wherein establishing estimated state variables of a substrate planarizing cycle includes providing an initial estimate of state variables, wherein the state variables include at least one of the depth of thickness of a substrate layer, the erosion rate of the substrate layer, and the endpoint thickness of the substrate layer.  
   
   
       3 . The computer readable medium according to  claim 1 , wherein establishing estimated state variables includes: 
 calculating total reflectance of a substrate that includes an array and a periphery region;    calculating an instantaneous change in reflectance of the substrate relative to the depth being planarized;    measuring actual reflectance;    updating the state variables by an extended Kalman filter engine estimate; and    estimating whether the reflectance is within a given variance of measured reflectance.    
   
   
       4 . The computer readable medium according to  claim 3 , wherein after estimating whether the reflectance is within a given variance the method includes: 
 if the estimated reflectance is not within the given variance: 
 providing a new estimate of state variables; and  
 recalculating total reflectance of the substrate;  
   and if the estimated reflectance is within the given variance: 
 calculating an endpoint time:  
 determining whether the elapsed physical process time is equal to the most recently calculated endpoint time;  
   and if the query receives an affirmative: 
 terminating the substrate planarizing process;  
   and if the query receives a negative: 
 providing a new estimate of state variables; and  
 recalculating total reflectance of the substrate.  
   
   
   
       5 . The computer readable medium according to  claim 3 , wherein after estimating whether the reflectance is within a given variance the method includes: 
 if the estimated reflectance is not within the given variance: 
 providing a new estimate of state variables; and  
 recalculating total reflectance of the substrate;  
   and if the estimated reflectance is within the given variance: 
 estimating the planarizing status of the substrate; and  
 altering at least one process parameter of the planarizing cycle.  
   
   
   
       6 . A computer readable medium for executing a set of instructions, the computer readable medium comprising: 
 estimating state variables of a physical process by use of an extended Kalman filter engine operating in an online control loop; and    transmitting the estimated state variables to a control loop of the physical process, including at least one of an estimated endpoint of the physical process based upon the estimates of the state variables, estimated total reflectance of a substrate that includes an array and a periphery region; and an estimated instantaneous change in reflectance of the substrate.    
   
   
       7 . The computer readable medium according to  claim 6 , wherein the online control loop is an inner control loop in communication with an offline loop including a second extended Kalman filter engine.  
   
   
       8 . The computer readable medium according to  claim 7 , wherein the offline loop and the online loop operate asynchronously.  
   
   
       9 . The computer readable medium according to  claim 7 , wherein the online loop generates at least two control cycles before receipt of the communication from the offline loop.  
   
   
       10 . The computer readable medium according to  claim 7 , wherein the offline loop includes a metrology data base.  
   
   
       11 . A computer readable medium for executing a set of instructions, the computer readable medium comprising: 
 instructions for communicating with a physical interface;    instructions for communicating with an online first, extended Kalman filter estimator;    instructions for communicating with an offline metrology data base including a second extended Kalman filter engine estimator;    communicating an information statement from the offline metrology data base to the first extended Kalman filter engine estimator; and    communicating a control statement from the online extended Kalman filter engine estimator to the physical interface.    
   
   
       12 . The computer readable medium according to  claim 11 , wherein the physical interface includes communication with a chemical-mechanical polishing apparatus.  
   
   
       13 . The computer readable medium according to  claim 11 , wherein the online, first extended Kalman filter engine estimator is part of an inner control loop of the set of instructions.  
   
   
       14 . The computer readable medium according to  claim 13 , wherein the inner control loop operates in a cycle that is asynchronous from the second extended Kalman filter engine.  
   
   
       15 . A computer readable medium for executing a set of instructions, the computer readable medium comprising: 
 instructions for communicating with a chemical-mechanical polishing interface;    instructions for communicating with an online first, extended Kalman filter extended Kalman filter engine estimator;    instructions for communicating with an offline metrology data base including a second extended Kalman filter engine estimator;    communicating an information statement from the offline metrology data base to the first extended Kalman filter engine estimator; and    communicating a control statement from the online extended Kalman filter engine estimator to the chemical-mechanical polishing interface.    
   
   
       16 . The computer readable medium according to  claim 15 , further including instruction controlling motion of a substrate to be polished, wherein the chemical-mechanical polishing interface receives a control statement form the online extended Kalman filter engine estimator that is generated from one of the state variable selected from depth of thickness of a layer that is being planarized, the erosion rate of a top layer over an array on the substrate, the erosion rate of a top layer over a periphery on the substrate, and the erosion rate ration of array erosion rate on the substrate over the array areas on the substrate.  
   
   
       17 . The computer readable medium according to  claim 15 , wherein the online, first extended Kalman filter engine estimator is part of an inner control loop.  
   
   
       18 . The computer readable medium according to  claim 15 , wherein the online, first extended Kalman filter engine estimator is part of an inner control loop, and wherein the inner control loop operates in a cycle that is asynchronous from the second extended Kalman filter engine.  
   
   
       19 . A computer readable medium for executing a set of instructions, the computer readable medium comprising: 
 instructions for communicating with a physical interface;    instructions for communicating with an online first, extended Kalman filter estimator;    instructions for communicating with an offline metrology data base in communication with the online estimator;    instructions for sending an information statement from the offline metrology data base to the extended Kalman filter estimator; and    instructions for sending a control statement from the online extended Kalman filter estimator to the physical interface.    
   
   
       20 . The computer readable medium according to  claim 19 , wherein the online first extended Kalman filter estimates state variables of a physical process controlled by the physical interface by operating in an online control loop; and 
 transmits the estimated state variables to a control loop of instructions for the physical process, including at least one of an estimated endpoint of the physical process based upon the estimates of the state variables, estimated total reflectance of a substrate that includes an array and a periphery region; and an estimated instantaneous change in reflectance of the substrate.    
   
   
       21 . The computer readable medium according to  claim 20 , wherein the online control loop is an inner control loop in communication with an offline loop including a second extended Kalman filter engine.  
   
   
       22 . The computer readable medium according to  claim 20 , wherein the offline loop and the online loop operate asynchronously.  
   
   
       23 . The computer readable medium according to  claim 21 , wherein the online loop generates at least two control cycles before receipt of the communication from the offline loop.  
   
   
       24 . The computer readable medium according to  claim 20 , wherein the offline loop includes a metrology data base.  
   
   
       25 . A computer readable medium for executing a set of instructions in a cyclic process, comprising: 
 an outer control loop, sending process parameter data from an nth process run, where n is an integer greater than zero, to update and improve accuracy in a process parameter;    an inner control loop including an extended Kalman filter receiving the process parameter data, calculating an updated process parameter and sending the updated process parameter to a process parameter controller; and    the process parameter controller receiving the updated process parameter and applying the updated process parameter to the (n +m)th process run, where m is greater than one.    
   
   
       26 . The computer readable medium of  claim 25 , wherein m is greater than 2.  
   
   
       27 . The computer readable medium of  claim 25 , wherein the process parameters include at least one of an estimated endpoint of the cyclic process based upon the estimates of the state variables, estimated total reflectance of a substrate that includes an array and a periphery region; and an estimated instantaneous change in reflectance of the substrate.  
   
   
       28 . The computer readable medium of  claim 25 , wherein the cyclic process includes a chemical-mechanical polishing process.  
   
   
       29 . The computer readable medium of  claim 25 , wherein the outer control loop and the inner control loop operate asynchronously.  
   
   
       30 . The computer readable medium of  claim 25 , wherein the outer control loop includes a second extended Kalman filter.  
   
   
       31 . A computer readable medium for executing a set of instructions, the computer readable medium comprising: 
 estimating a state variable for a physical process by use of an extended Kalman Filter that operates in an online control loop;    applying a control statement to the physical process from the online control loop; and    sending an information statement from an offline metrology control loop to the online control loop, wherein the information statement optionally changes estimating the state variable.    
   
   
       32 . The computer readable medium according to  claim 31 , wherein the offline metrology control loop includes an extended Kalman Filter engine.  
   
   
       33 . The computer readable medium according to  claim 31 , wherein the online control loop and the offline metrology control loop are operated asynchronously.  
   
   
       34 . The computer readable medium according to  claim 31 , wherein the online control loop generates at least two control cycles before receipt of the information statement from the offline metrology control loop.