Low Power RF Tuning Using Optical and Non-Reflected Power Methods

Abstract

Aspects of the present invention include methods and apparatuses that may be used for monitoring and adjusting plasma in a substrate processing system by using a plasma data monitoring assembly. For example, an optical instrument adapted to measure properties of light over a specific portion of the electromagnetic spectrum may be used to detect one or more wavelength intensities from the plasma. Then, an electronic device, for example a computer software may analyze the wavelength intensities and a match circuit may then be adjusted. In this way, consistent plasma may be obtained. In other embodiments, the present invention may utilize the relationship between chamber pressure, substrate temperature, coil currents and/or the plasma in order to adjust and maintain a repeatable plasma process.

1 . A method for monitoring plasma in a substrate processing system, comprising:
 monitoring reflected electromagnetic radiation reflected from a plasma within a chamber;   associating the reflected electromagnetic radiation to an RF power within the processing system; and   adjusting a matching circuit to maintain a repeatable plasma condition.   
     
     
         2 . The method of  claim 1 , wherein the electromagnetic radiation reflected from the plasma source may have a wavelength between about 200 nm and about 800 nm and the substrate processing system is adapted to detect the wavelength. 
     
     
         3 . The method of  claim 1 , wherein the monitoring the reflected electromagnetic radiation is performed by utilizing an interferometer. 
     
     
         4 . The method of  claim 1 , wherein the monitoring the reflected electromagnetic radiation is performed by utilizing a spectrometer. 
     
     
         5 . The method of  claim 1 , wherein the adjusting the match circuit is performed before and after processing of the substrate. 
     
     
         6 . The method of  claim 1 , wherein the substrate processing system is a plasma nitridation chamber. 
     
     
         7 . The method of  claim 1 , wherein the RF power has an effective power of about 5 Watts to about 30 KWatts. 
     
     
         8 . The method of  claim 1 , wherein the reflected electromagnetic radiation is optical. 
     
     
         9 . A method for controlling a plasma in a substrate processing system, comprising:
 Controlling a first set of wavelength intensities of reflected electromagnetic radiation reflected from a plasma within a chamber before processing of first set of one or more substrates;   associating the first wavelength intensity of reflected electromagnetic radiation to an RF power within the processing system;   adjusting a matching circuit based on the reflected electromagnetic radiation;   processing the first set of one or more substrates in the substrate processing system;   controlling a second a set of wavelength intensities of reflected electromagnetic radiation reflected from a plasma within a chamber;   associating the second wavelength intensity of reflected electromagnetic radiation to an RF power within the processing system; and   adjusting a matching circuit based on the first or the second set of reflected electromagnetic radiation, while processing a second set of one or more substrates.   
     
     
         10 . The method of  claim 9 , wherein the second set of wavelength intensities are selected based on substrate type or process recipe. 
     
     
         11 . The method of  claim 9 , wherein the first set of one or more substrates and the second set of one or more substrates are of different types. 
     
     
         12 . The method of  claim 9 , wherein the electromagnetic radiation reflected from the plasma source may have a wavelength between about 200 nm and about 800 nm and the substrate processing system is adapted to detect the wavelength. 
     
     
         13 . The method of  claim 9 , wherein the controlling the reflected electromagnetic radiation is performed by utilizing an interferometer. 
     
     
         14 . The method of  claim 9 , wherein the controlling the reflected electromagnetic radiation is performed by utilizing a spectrometer. 
     
     
         15 . The method of  claim 9 , wherein the adjusting the match circuit is performed before and after performing a service maintenance. 
     
     
         16 . The method of  claim 9 , wherein the substrate processing system is a plasma nitridation chamber. 
     
     
         17 . The method of  claim 9 , wherein the RF power has an effective power of about 5 Watts to about 30 KWatts. 
     
     
         18 . Apparatus for monitoring a plasma in a substrate processing system, comprising:
 a plasma chamber;   an RF power source;   an RF matching circuit, wherein the RF matching circuit is controllable;   a plasma data monitoring assembly for acquiring data related to the plasma, wherein the plasma data collecting assembly is disposed within the processing chamber; and   a computer, wherein the computer comprises a software program adapted to model a relationship between the data collected by the plasma data monitoring assembly and the RF power and is capable of providing values for controllable elements in the RF match circuit for a repeatable process.   
     
     
         19 . The apparatus of  claim 18 , wherein the plasma data monitoring assembly further comprising:
 a first reactance element; and   a second reactance element;   
     
     
         20 . The apparatus of  claim 18 , wherein the plasma data monitoring assembly further comprises a third reactance element. 
     
     
         21 . The apparatus of  claim 18 , wherein the plasma data monitoring assembly is an interferometer. 
     
     
         22 . The apparatus of  claim 18 , wherein the plasma data monitoring assembly is an spectrometer. 
     
     
         23 . The apparatus of  claim 18 , wherein the substrate processing system is a plasma nitridation chamber. 
     
     
         24 . The method of  claim 18 , wherein the monitoring data assembly is adapted to detect electromagnetic radiation reflected from the plasma with wavelengths between about 200 nm and about 800 nm. 
     
     
         25 . The method of  claim 18 , wherein the RF power has an effective power of about 5 KWatts to about 30 KWatts. 
     
     
         26 . Apparatus for monitoring a plasma in a substrate processing system, comprising:
 a plasma chamber;   an RF power source;   an RF matching circuit, wherein the RF matching circuit is controllable; and   a computer, wherein the computer comprises a data monitoring assembly adapted to model a relationship between the data collected by the data monitoring assembly and the RF power and is capable of providing values for controllable elements in the RF match circuit for a repeatable process.   
     
     
         27 . The apparatus of  claim 26 , wherein the data collected is coil current; 
     
     
         28 . The apparatus of  claim 26 , wherein the data collected is electron density. 
     
     
         29 . The apparatus of  claim 26 , wherein the data collected is electron-neutron ratio. 
     
     
         30 . The apparatus of  claim 26 , wherein the data collected is a temperature of a substrate. 
     
     
         31 . The apparatus of  claim 25 , wherein the data collected is related to the plasma generated within the chamber. 
     
     
         32 . The apparatus of  claim 26 , wherein the data collected comprises two or more elements from the group consisting of electromagnetic radiation reflected from the plasma source, coil current, electron density, substrate temperature and electron-neutron ratio.