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

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 plasma frequency that exists after the plasma is struck, the measured plasma frequency 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 plasma frequency value with an attribute of the process, if the measured plasma frequency value is outside of a predefined plasma frequency 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 plasma frequency that exists after said plasma is struck, said measured plasma frequency 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 plasma frequency value is outside of a predefined plasma frequency value envelope, correlating said measured plasma frequency value with an attribute of said process.    
   
   
       2 . The method of  claim 1  wherein said obtaining said measured plasma frequency values is performed at a target RF frequency.  
   
   
       3 . The method of  claim 2  wherein said target RF frequency is about 2 MHz.  
   
   
       4 . The method of  claim 2  wherein said target RF frequency is about 27 MHz.  
   
   
       5 . The method of  claim 2  wherein said target 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 plasma frequency value is performed using said V/I probe.  
   
   
       7 . The method of  claim 6  wherein said measured plasma frequency value represents a value of a phase angle measurement.  
   
   
       8 . The method of  claim 6  wherein said measured plasma frequency value represents a value of an amplitude measurement.  
   
   
       9 . The method of  claim 1  wherein said predefined plasma frequency value envelope includes a plasma frequency lower control limit.  
   
   
       10 . The method of  claim 9  wherein said plasma frequency lower control limit is within 3σ of a predefined plasma frequency target value.  
   
   
       11 . The method of  claim 1  wherein said predefined plasma frequency value envelope includes a plasma frequency upper control limit.  
   
   
       12 . The method of  claim 11  wherein said plasma frequency upper control limit is within 3σ of a predefined plasma frequency target value.  
   
   
       13 . The method of  claim 1  wherein said predefined plasma frequency value envelope includes a plasma frequency lower control limit and a plasma frequency 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 plasma frequency that exists after said plasma is struck, said measured plasma frequency 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 plasma frequency value is outside of a predefined plasma frequency value envelope, means of correlating said measured plasma frequency value with an attribute of said process.    
   
   
       24 . The apparatus of  claim 23  wherein said obtaining said measured plasma frequency value is performed at a target RF frequency.  
   
   
       25 . The apparatus of  claim 24  wherein said target RF frequency is about 2 MHz.  
   
   
       26 . The apparatus of  claim 24  wherein said target RF frequency is about 27 MHz.  
   
   
       27 . The apparatus of  claim 24  wherein said target 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 plasma frequency value is includes using said V/I probe.  
   
   
       29 . The apparatus of  claim 28  wherein said measured plasma frequency value represents a value of a phase angle measurement.  
   
   
       30 . The apparatus of  claim 28  wherein said measured plasma frequency value represents a value of an amplitude measurement.  
   
   
       31 . The apparatus of  claim 23  wherein said predefined plasma frequency value envelope includes a plasma frequency lower control limit.  
   
   
       32 . The apparatus of  claim 31  wherein said plasma frequency lower control limit is within 3σ of a predefined plasma frequency target value.  
   
   
       33 . The apparatus of  claim 23  wherein said predefined plasma frequency value envelope includes a plasma frequency upper control limit.  
   
   
       34 . The apparatus of  claim 33  wherein said plasma frequency upper control limit is within 3σ of a predefined plasma frequency target value.  
   
   
       35 . The apparatus of  claim 23  wherein said predefined plasma frequency value envelope includes a plasma frequency lower control limit and an 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.