Feedback control of sub-atmospheric chemical vapor deposition processes

Abstract

A method of film deposition in a sub-atmospheric chemical vapor deposition (CVD) process includes (a) providing a model for sub-atmospheric CVD deposition of a film that identifies one or more film properties of the film and at least one deposition model variable that correlates with the one or more film properties; (b) depositing a film onto a wafer using a first deposition recipe comprising at least one deposition recipe parameter that corresponds to the at least one deposition variable; (c) measuring a film property of at least one of said one or more film properties for the deposited film of step (b); (d) calculating an updated deposition model based upon the measured film property of step (c) and the model of step (a); and (e) calculating an updated deposition recipe based upon the updated model of step (d) to maintain a target film property. The method can be used to provide feedback to a plurality of deposition chambers or to control a film property other than film thickness.

1 . A sub-atmospheric chemical vapor deposition tool for deposition of a film, comprising: 
 a sub-atmospheric chemical vapor deposition apparatus comprising a pressure chamber, a vacuum system, means for heating a wafer and a gas delivery system;    controlling means capable of controlling an operating parameter of the deposition process; and    a controller operatively coupled to the controlling means, the controller operating the controlling means to adjust the operating parameter of the deposition process as a function of a model for a film property, the model comprising:    a deposition model for sub-atmospheric CVD deposition of a film that identifies one or more film properties of the film and at least one deposition model variable that correlates with the one or more film properties.    
     
     
         2 . The tool of  claim 1 , wherein the model defines a plurality of regions on a wafer and identifies a deposition variable and a film property for each of at least two regions of the wafer.  
     
     
         3 . The tool of  claim 1 , wherein the operating parameter comprises a parameter selected from the group consisting of deposition time, wafer temperature, ozone flow rate, oxygen flow rate, reactive gas flow rate, carrier gas flow rate, dopant gas flow rate, chamber pressure and shower head spacing from the wafer.  
     
     
         4 . The tool of  claim 3 , wherein the film property is selected from the group consisting of film thickness, stress, refractive index, dopant concentration, and extinction coefficient.  
     
     
         5 . The tool of  claim 3 , wherein the model defines deposition of a plurality of films onto a plurality of wafers in a plurality of deposition chambers.  
     
     
         6 . The tool of  claim 5 , wherein the model provides for independent control of at least one operating parameter for each deposition chamber.  
     
     
         7 . The tool of  claim 5 , wherein model provides for common control of at least one operating parameter for all deposition chambers.  
     
     
         8 . The tool of  claim 5 , wherein the deposition recipe of step (b) in each chamber is the same.  
     
     
         9 . The tool of  claim 5 , wherein the deposition recipe of step (b) in each chamber is different.  
     
     
         10 . The tool of  claim 5 , wherein the calculating step of step (e) comprises calculating updated deposition recipes for each of the plurality of deposition chambers.  
     
     
         11 . The tool of  claim 5 , wherein the model provides for the effect of tool idle time of the deposition process.  
     
     
         12 . The tool of  claim 11 , wherein the model defines a first deposition time when the idle time is more than a predetermined period and a second deposition time when the idle time is less than the predetermined period.  
     
     
         13 . The tool of  claim 1 , wherein the model evaluates the reliability of a measurement of a film property.  
     
     
         14 . A computer readable medium comprising instructions being executed by a computer, the instructions including a computer-implemented software application for a sub-atmospheric chemical vapor deposition process, the instructions for implementing the process comprising: 
 a) receiving data from a sub-atmospheric chemical vapor deposition tool relating to the film property of at least one wafer processed in the sub-atmospheric chemical vapor deposition process; and    b) calculating, from the data of step (a), an updated deposition model, wherein the updated deposition model is calculated by determining the difference between an output of a film deposition model and the data of step (a).    
     
     
         15 . The medium of  claim 14 , further comprising: 
 c) calculating, using the updated model of step (b) and a target output value for the film property, an updated deposition recipe.    
     
     
         16 . The medium of  claim 14 , wherein the data of step (a) further includes one or more deposition parameters selected from the group consisting of deposition time, wafer temperature, ozone flow rate, oxygen flow rate, reactive gas flow rate, carrier gas flow rate, dopant gas flow rate, chamber pressure and shower head spacing from the wafer.  
     
     
         17 . The medium of  claim 14 , wherein the film property is selected from the group consisting of film thickness, stress, refractive index, dopant concentration, and extinction coefficient.  
     
     
         18 . A sub-atmospheric chemical deposition tool, comprising: 
 a) modeling means for identifying one or more film properties of a film and at least one deposition model variable that correlates with the one or more film properties in a sub-atmospheric CVD deposition process;    b) means for depositing a film onto a wafer using a first deposition recipe comprising at least one deposition recipe parameter that corresponds to the at least one deposition variable;    c) means for measuring a film property of at least one of said one or more film properties for the deposited film of step (b);    d) means for calculating an updated deposition model based upon the measured film property of step (c) and the model of step (a); and    e) means for calculating an updated deposition recipe based upon the updated model of step (d) to maintain a target film property.    
     
     
         19 . The sub-atmospheric CVD tool of  claim 18 , wherein the model defines deposition of a plurality of films onto a plurality of wafers in a plurality of deposition chambers.  
     
     
         20 . The sub-atmospheric CVD tool of  claim 19 , wherein the model provides for independent control of at least one deposition parameter for at least two of said plurality of deposition chambers.  
     
     
         21 . The sub-atmospheric CVD tool of  claim 19 , wherein model provides for common control of at least one deposition parameter for at least two of said plurality of deposition chambers.  
     
     
         22 . The sub-atmospheric CVD tool of  claim 19 , wherein the deposition recipe of step (b) in each chamber is the same  
     
     
         23 . The sub-atmospheric CVD tool of  claim 19 , wherein the deposition recipe of step (b) in each chamber is different.  
     
     
         24 . The sub-atmospheric CVD tool of  claim 19 , wherein the calculating step of step (e) comprises calculating updated deposition recipes for each of the plurality of deposition chambers.  
     
     
         25 . The sub-atmospheric CVD tool of  claim 19 , wherein the model provides for the effect of tool idle time of the deposition process.  
     
     
         26 . The sub-atmospheric CVD tool of  claim 25 , wherein the model defines a first deposition time when the idle time is more than a predetermined period and a second deposition time when the idle time is less than the predetermined period.  
     
     
         27 . A computer-implemented apparatus for controlling film deposition in a sub-atmospheric chemical vapor deposition (CVD) process, comprising: 
 a) modeling means for modeling a sub-atmospheric CVD deposition of a film that identifies one or more film properties of the film and at least one deposition model variable that correlates with the one or more film properties;    b) deposition means for depositing a film onto a wafer using a first deposition recipe comprising at least one deposition recipe parameter that corresponds to the at least one deposition variable;    c) measuring means for determining a film property of at least one of said one or more film properties for the deposited film of step (b); and    d) calculating means for determining an updated deposition model based upon the measured film property of step (c) and the model of step (a).