Fast arc detecting match network

Abstract

A method of detecting plasma asymmetry in a radio frequency plasma processing system, the method including providing a radio frequency power to a reaction chamber having an approximate chamber symmetry axis and receiving from a plurality of broadband electromagnetic sensors a radio frequency signal. The method also including processing the radio frequency signals using Fourier analysis and determining based on the Fourier analysis of the radio frequency signals that a plasma asymmetry has occurred within the reaction chamber.

What is claimed is: 
     
         1 . An automated impedance matching network for controlling a plasma processing system including a plasma reaction chamber, comprising:
 a broadband RF sensor within or adjacent to the plasma chamber generating sensor signals associated with a plasma process within the plasma chamber;   a processor performing a method, comprising:
 receiving the sensor signals; 
 detecting amplitudes and phases of fundamental and harmonic frequency components of the sensor signals, 
 determining non-uniformity in plasma density within the plasma chamber based on the amplitudes and phases of the fundamental and harmonic frequency components of the sensor signals, 
 recognizing a plasma fault condition based on the non-uniformity in the plasma density, 
 ordering a corrective action in response to the plasma fault condition. 
   
     
     
         2 . The automated impedance matching network of  claim 1 , further comprising an azimuthal array of broadband radio frequency sensors positioned around an axis of symmetry of the plasma reaction chamber generating the sensor signals. 
     
     
         3 . The automated impedance matching network of  claim 1 , further comprising an array of broadband radio frequency sensors positioned on or build into a sidewall of the plasma reaction chamber generating the sensor signals. 
     
     
         4 . The automated impedance matching network of  claim 1 , further comprising an array of broadband radio frequency sensors positioned on or proximate to an electrode conducting RF power within the plasma reaction chamber. 
     
     
         5 . The automated impedance matching network of  claim 1 , wherein the broadband radio frequency sensor is located in a dielectric material exhibiting a dielectric constant less than 5 positioned in an electrode conducting RF power within the plasma reaction chamber. 
     
     
         6 . The automated impedance matching network of  claim 1 , wherein the broadband radio frequency sensor is coupled to a signal cable passing through a vacuum wall of the plasma reaction chamber. 
     
     
         7 . The automated impedance matching network of  claim 1 , wherein the broadband radio frequency sensor is coupled to a wireless communication link. 
     
     
         8 . The automated impedance matching network of  claim 1 , wherein the corrective action comprises triggering an alarm. 
     
     
         9 . The automated impedance matching network of  claim 1 , wherein the corrective action comprises operating an electronically controlled capacitor of the impedance matching network. 
     
     
         10 . The automated impedance matching network of  claim 1 , wherein the corrective action comprises altering a fundamental frequency of RF power supplied to the plasma chamber within a range of one-tenth to 10 percent of the fundamental frequency. 
     
     
         11 . The automated impedance matching network of  claim 1 , wherein the corrective action comprises interrupting RF power supplied to the plasma chamber. 
     
     
         12 . The automated impedance matching network of  claim 1 , wherein the corrective action comprises shutting down the RF processing system for maintenance. 
     
     
         13 . The automated impedance matching network of  claim 1 , wherein the corrective action comprises discarding a substrate affected by the plasma fault condition. 
     
     
         14 . The automated impedance matching network of  claim 1 , wherein the corrective action comprises conducting diagnostics on a substrate affected by the plasma fault condition to determine nano-scale substrate feature non-uniformities associated with the plasma fault condition. 
     
     
         15 . The automated impedance matching network of  claim 1 , wherein the non-uniformity in the plasma density etching is associated with a nano-scale substrate feature non-uniformity below 3 nanometers on a substrate layer less than 10 nanometers thick. 
     
     
         16 . The automated impedance matching network of  claim 1 , further comprising detecting the non-uniformity in the plasma density within 50 microseconds. 
     
     
         17 . The automated impedance matching network of  claim 1 , further comprising detecting the non-uniformity in the plasma density within one microsecond. 
     
     
         18 . The automated impedance matching network of  claim 1 , wherein the processor utilizes substantially continuous Fourier analysis to identify the amplitudes and phases of the fundamental and harmonic frequency components. 
     
     
         19 . An automated impedance matching network for controlling a plasma processing system including a plasma reaction chamber, comprising:
 a broadband RF sensor within or adjacent to the plasma chamber generating sensor signals associated a plasma process within the plasma chamber;   a processor performing a method, comprising:
 receiving the sensor signals; 
 detecting amplitudes and phases of fundamental and harmonic frequency components of the sensor signals; 
 recognizing a plasma fault condition based on the amplitudes and phases of fundamental and harmonic frequency components of the sensor signals, 
 ordering a corrective action in response to the plasma fault condition comprising one or more of (a) changing a frequency of RF power supplied to the plasma chamber, (b) pulsing RF power supplied to the plasma chamber, (c) changing a duty cycle of pulsed RF power supplied to the plasma chamber. 
   
     
     
         20 . An automated impedance matching network for controlling a plasma processing system including a plasma reaction chamber, comprising:
 a broadband RF sensor within or adjacent to the plasma chamber generating sensor signals associated with a plasma process within the plasma chamber;   a processor performing a method, comprising:
 receiving the sensor signals; 
 detecting amplitudes and phases of fundamental and harmonic frequency components of the sensor signals; 
 determining an acceleration in the amplitude of one or more of the frequency components; 
 predicting an immediate future plasma fault condition based on the acceleration; 
 ordering a corrective action in response to the predicted plasma fault condition.