Multi-anode device and methods for sputter deposition

Abstract

A method and apparatus for vacuum coating plural articles employs a drum work holder configuration and a sputter source with a plurality of individually controlled anodes for effectively providing uniform coatings on articles disposed at different locations on the drum work holder. A small number of measured process parameters are used to control a small number of process variable to improve coating uniformity from batch to batch.

We claim:  
     
         1 . A method for controlling the application of thin coatings applied to a substrate in a vacuum sputtering system, comprising: 
 measuring an electrical parameter and a pressure parameter of the sputtering system during a sputtering run and producing measurement signals indicative of the parameters;    producing control signals responsive to said measurement signals based on a rule set; and    using said control signals to adjust in real time at least one process gas flow rate while sputtering.    
     
     
         2 . The method of  claim 1 , wherein the electrical parameter measured is a cathode voltage and the pressure parameter measured is total system pressure.  
     
     
         3 . The method of  claim 2 , wherein the sputtering performed is reactive sputtering and the process gas flow rates that are controlled are a reactive gas flow rate and a non-reactive gas flow rate.  
     
     
         4 . The method of  claim 1 , wherein the control signals are determined by a fuzzy-logic computation employing the electrical parameter and the pressure parameter as inputs.  
     
     
         5 . The method of  claim 1 , wherein the control signals are determined from a computerized look-up table based on the electrical parameter and the pressure parameter as inputs.  
     
     
         6 . The method of  claim 5 , wherein the look-up table employs the following rule base:  
       
         
           
                 
                 
                 
               
                     
                 
                     
                 
                   Cathode Voltage 
                   Total System Pressure 
                   Flow Adjustment 
                 
                     
                 
                   Low 
                   High 
                   Decrease non-reactive gas 
                 
                   Low 
                   Low 
                   Increase reactive gas 
                 
                   High 
                   High 
                   Decrease reactive gas 
                 
                   High 
                   Low 
                   Increase non-reactive gas 
                 
                   OK 
                   High 
                   Decrease non-reactive gas 
                 
                   OK 
                   Low 
                   Increase non-reactive gas 
                 
                   High 
                   OK 
                   Decrease reactive gas 
                 
                   Low 
                   OK 
                   Increase reactive gas 
                 
                     
                 
                     
                 
             
                
                
                
                
               
               
                
                
                
                
                
                
                
                
                
                
               
            
           
         
       
     
     
         7 . The method of  claim 5 , wherein the look-up table employs a decision structure for adjusting the at least one process gas flow rate based on a categorization of the electrical parameter and a categorization of the pressure parameter.  
     
     
         8 . The method of  claim 6 , wherein the non-reactive gas is argon and the reactive gas is oxygen.  
     
     
         9 . A method for controlling the application of a coating to a substrate in a coating system, comprising: 
 measuring a first system parameter and a second system parameter of the coating system during a coating run and producing measurement signals indicative of the system parameters;    producing control signals responsive to said measurement signals based on a fuzzy-logic rule set; and    using said control signals to control in real time at least one process variable of the coating system while applying a coating.    
     
     
         10 . The method of  claim 9 , wherein applying the coating comprises sputtering, wherein the first system parameter measured is a cathode voltage of a sputtering source, and wherein the second system parameter measured is a gas pressure.  
     
     
         11 . The method of  claim 10 , wherein the at least one process variable comprises a flow rate of a first gas and a flow rate of a second gas.  
     
     
         12 . The method of  claim 9 , wherein the control signals are determined by a fuzzy-logic computation based upon the first system parameter and the second system parameter as inputs.  
     
     
         13 . The method of  claim 9 , wherein the control signals are determined from a computerized look-up table based on the first system parameter and the second system parameter as inputs.  
     
     
         14 . The method of  claim 9 , wherein the at least one process variable comprises a gas partial pressure.  
     
     
         15 . A control system for controlling the application of a coating to a substrate in a coating system, comprising: 
 a fuzzy-logic controller; and    an interface coupled to the fuzzy-logic controller,    wherein the interface is configured to receive first and second measurement signals corresponding to first and second measured system parameters, respectively, of a coating system during a coating run,    wherein the fuzzy-logic controller is configured to receive the first and second measurement signals from the interface and to produce control signals responsive to said first and second measurement signals based on a fuzzy-logic rule set, and    wherein the interface is configured to provide the control signals produced by the fuzzy-logic controller to the coating system to control at least one process variable of the coating system during application of a coating.    
     
     
         16 . The control system of  claim 15 , wherein the fuzzy-logic controller is configured to produce the control signals using a cathode voltage of a sputtering source as the first measured system parameter and using a total system pressure as the second measured system parameter.  
     
     
         17 . The control system of  claim 16 , wherein the at least one process variable comprises a flow rate of a first gas and a flow rate of a second gas.  
     
     
         18 . The control system of  claim 15 , wherein the fuzzy-logic controller is configured to produce the control signals using a fuzzy-logic computation based upon the first measurement signal corresponding to the first measured system parameter and the second measurement signal corresponding to the second measured system parameter as inputs.  
     
     
         19 . The control system of  claim 15 , wherein the fuzzy-logic controller is configured to produce the control signals using a computerized look-up table based on the first measurement signal corresponding to the first measured system parameter and the second measurement signal corresponding to the second measured system parameter as inputs.  
     
     
         20 . The control system of  claim 15 , wherein the at least one process variable comprises a gas partial pressure.