Plasma processing apparatus

Abstract

A plasma processing apparatus includes a stage disposed in a processing chamber for mounting a wafer, a plasma generation chamber disposed above the processing chamber for plasma generation using process gas, a plate member having multiple introduction holes, made of a dielectric material, disposed above the stage and between the processing chamber and the plasma generation chamber, and a lamp disposed around the plate member for heating the wafer. The plasma processing apparatus further includes an external IR light source, an emission fiber arranged in the stage, that outputs IR light from the external IR light source toward a wafer bottom, and a light collection fiber for collecting IR light from the wafer. Data obtained using only IR light from the lamp is subtracted from data obtained also using IR light from the external IR light source during heating of the wafer. Thus, a wafer temperature is determined.

What is claimed is: 
     
         1 . A plasma processing apparatus comprising:
 a vacuum vessel including therein a processing chamber, having a reduced pressure, to which process gas is supplied;   a stage disposed at an inner lower position of the processing chamber, the stage having an upper surface, and configured to mount a wafer to be processed, on the upper surface;   a plasma generation chamber disposed above the processing chamber, wherein plasma is generated in the plasma generation chamber using the process gas;   a plate member made of a dielectric material disposed above the upper surface of the stage and between the processing chamber and the plasma generation chamber, the plate member having a plurality of introduction holes for introducing the process gas;   a lamp arranged to circumferentially surround the plate member, and configured to heat the wafer;   an external infrared (IR) light source for determination of a wafer temperature;   a spectroscope; and   a detector configured to detect dispersed IR light, wherein   the stage has a plurality of fiber installation openings,   each of the plurality of fiber installation openings receives:
 an IR light emission fiber configured to output, from a rear side of the wafer, IR light from the external IR light source for determination of the wafer temperature, and 
 an IR light collection fiber configured to collect IR light passing through, and reflected by, the wafer, 
   an optical path switch configured to switch on and off IR light emission to the wafer, and a light splitter configured to split IR light into multiple beams, are both provided at an intermediate location on the IR light emission fiber,   a plurality of the IR light collection fibers are connected to an optical multiplexer, and   IR light corresponding to a selected one of the channels of the optical multiplexer is transmitted to the spectroscope, and is measured by the detector.   
     
     
         2 . The plasma processing apparatus according to  claim 1 , wherein each of the IR light emission and collection fibers is arranged at an angle with respect to a wafer plane of the wafer mounted on the stage. 
     
     
         3 . The plasma processing apparatus according to  claim 1 , wherein a quartz tube is inserted in each of the plurality of fiber installation openings in the stage, and the quartz tube is terminated at one end of the quartz tube, and receives therein the IR light emission fiber and the IR light collection fiber. 
     
     
         4 . The plasma processing apparatus according to  claim 1 , wherein wavelength profile data of IR light intensity obtained during an “on” state of the optical path switch is subtracted from wavelength profile data of IR light intensity obtained during an “off” state of the optical path switch to calculate an infrared absorption edge wavelength from the data obtained by the subtraction to estimate the wafer temperature. 
     
     
         5 . The plasma processing apparatus according to  claim 1 , wherein
 the plasma processing apparatus processes the wafer by repeating
 an adsorption step of adsorbing of particles in the plasma on a film disposed on a surface of the wafer to generate a product layer, 
 a desorption step, performed after the adsorption step, of desorbing of the product layer by heating the wafer by the lamp in the processing chamber, and 
 a cooling step of cooling the wafer after the desorption step, 
   the lamp is lit, during the adsorption step and during the cooling step, at power lower than power used during the desorption step, and   light from the lamp is used to determine the wafer temperature.