Methods and apparatus for monitoring a process in a plasma processing system by measuring impedance

Abstract

A method for in-situ monitoring a process in a plasma processing system having a plasma processing chamber is disclosed. The method includes positioning a substrate in the plasma processing chamber. The method also includes striking a plasma within the plasma processing chamber while the substrate is disposed within the plasma processing chamber. The method further includes obtaining a measured impedance that exists after the plasma is struck, the measured impedance value having a first value when the plasma is absent and at least a second value different from the first value when the plasma is present. The method also includes correlating the measured impedance value with an attribute of the process, if the measured impedance value is outside of a predefined impedance value envelope.

1 . A method for in-situ monitoring a process in a plasma processing system having a plasma processing chamber, comprising: 
 positioning a substrate in said plasma processing chamber;    striking a plasma within said plasma processing chamber while said substrate is disposed within said plasma processing chamber;    obtaining a measured impedance that exists after said plasma is struck, said measured impedance value having a first value when said plasma is absent and at least a second value different from said first value when said plasma is present;    if said measured impedance value is outside of a predefined impedance value envelope, correlating said measured impedance value with an attribute of said process.    
   
   
       2 . The method of  claim 1  wherein said obtaining said measured impedance values is performed at a specific RF frequency.  
   
   
       3 . The method of  claim 2  wherein said specific RF frequency is about 2 MHz.  
   
   
       4 . The method of  claim 2  wherein said specific RF frequency is about 27 MHz.  
   
   
       5 . The method of  claim 2  wherein said specific RF frequency is about 13.56 MHz.  
   
   
       6 . The method of  claim 2  wherein said plasma processing system includes a RF generator having a V/I probe, said obtaining said measured impedance value is performed using said V/I probe.  
   
   
       7 . The method of  claim 6  wherein said measured impedance value represents a value of a phase angle measurement.  
   
   
       8 . The method of  claim 6  wherein said measured impedance value represents a value of an amplitude measurement.  
   
   
       9 . The method of  claim 1  wherein said predefined impedance value envelope includes an impedance lower control limit.  
   
   
       10 . The method of  claim 9  wherein said impedance lower control limit is within 3σ of a predefined impedance target value.  
   
   
       11 . The method of  claim 1  wherein said predefined impedance value envelope includes an impedance upper control limit.  
   
   
       12 . The method of  claim 11  wherein said impedance upper control limit is within 3σ of a predefined impedance target value.  
   
   
       13 . The method of  claim 1  wherein said predefined impedance value envelope includes an impedance lower control limit and an impedance upper control limit.  
   
   
       14 . The method of  claim 1  wherein said substrate is a semiconductor wafer.  
   
   
       15 . The method of  claim 1  wherein said substrate is a glass panel.  
   
   
       16 . The method of  claim 1  wherein said attribute of said substrate represents an etch rate while etching said substrate.  
   
   
       17 . The method of  claim 1  wherein said attribute of said substrate represents a selectivity rate while etching said substrate.  
   
   
       18 . The method of  claim 1  wherein said attribute of said substrate represents an etch uniformity measurement while etching said substrate.  
   
   
       19 . The method of  claim 1  wherein said plasma processing system is a capacitively coupled plasma processing system.  
   
   
       20 . The method of  claim 1  wherein said plasma processing system is an inductively coupled plasma processing system.  
   
   
       21 . The method of  claim 1  wherein said plasma processing system is an atmospheric plasma processing system.  
   
   
       22 . The method of  claim 1  wherein said plasma processing system is a frequency-tuned coupled plasma processing system.  
   
   
       23 . An apparatus for in-situ monitoring of a process in a plasma processing system having a plasma processing chamber, comprising: 
 means for positioning a substrate in said plasma processing chamber;    means for striking a plasma within said plasma processing chamber while said substrate is disposed within said plasma processing chamber;    means for obtaining a measured impedance that exists after said plasma is struck, said measured impedance value having a first value when said plasma is absent and at least a second value different from said first value when said plasma is present;    if said measured impedance value is outside of a predefined impedance value envelope, means of correlating said measured impedance value with an attribute of said process.    
   
   
       24 . The apparatus of  claim 23  wherein said obtaining said measured impedance value is performed at a specific RF frequency.  
   
   
       25 . The apparatus of  claim 24  wherein said specific RF frequency is about 2 MHz.  
   
   
       26 . The apparatus of  claim 24  wherein said specific RF frequency is about 27 MHz.  
   
   
       27 . The apparatus of  claim 24  wherein said specific RF frequency is about 13.56 MHz.  
   
   
       28 . The apparatus of  claim 24  wherein said plasma processing system includes a RF generator having a V/I probe, said means of obtaining said measured impedance value is includes using said V/I probe.  
   
   
       29 . The apparatus of  claim 28  wherein said measured impedance value represents a value of a phase angle measurement.  
   
   
       30 . The apparatus of  claim 28  wherein said measured impedance value represents a value of an amplitude measurement.  
   
   
       31 . The apparatus of  claim 23  wherein said predefined impedance value envelope includes an impedance lower control limit.  
   
   
       32 . The apparatus of  claim 31  wherein said impedance lower control limit is within 3σ of a predefined impedance target value.  
   
   
       33 . The apparatus of  claim 23  wherein said predefined impedance value envelope includes an impedance upper control limit.  
   
   
       34 . The apparatus of  claim 33  wherein said impedance upper control limit is within 3σ of a predefined impedance target value.  
   
   
       35 . The apparatus of  claim 23  wherein said predefined impedance value envelope includes an impedance lower control limit and an impedance upper control limit.  
   
   
       36 . The apparatus of  claim 23  wherein said substrate is a semiconductor wafer.  
   
   
       37 . The apparatus of  claim 23  wherein said substrate is a glass panel.  
   
   
       38 . The apparatus of  claim 23  wherein said attribute of said substrate represents an etch rate while etching said substrate.  
   
   
       39 . The apparatus of  claim 23  wherein said attribute of said substrate represents a selectivity rate while etching said substrate.  
   
   
       40 . The apparatus of  claim 23  wherein said attribute of said substrate represents an etch uniformity measurement while etching said substrate.  
   
   
       41 . The apparatus of  claim 23  wherein said plasma processing system is a capacitively coupled plasma processing system.  
   
   
       42 . The apparatus of  claim 23  wherein said plasma processing system is an inductively coupled plasma processing system.  
   
   
       43 . The apparatus of  claim 23  wherein said plasma processing system is an atmospheric plasma processing system.  
   
   
       44 . The apparatus of  claim 23  wherein said plasma processing system is a frequency-tuned coupled plasma processing system.