Plasma processing apparatus

Abstract

In the plasma processing apparatus of the present invention, a first electrode ( 21 ) for connecting a high frequency electric power source ( 40 ) in a chamber is arranged to be opposed to a second electrode ( 5 ). A substrate (W) to be processed is placed between the electrodes. There is provided a harmonic absorbing member ( 51 ) for being able to absorb harmonics of the high frequency electric power source ( 40 ) so as to come in contact with a peripheral portion or circumference of a face of the first electrode 21 , which is opposite the second electrode ( 5 ). The harmonic absorbing member absorbs the reflected harmonic before the harmonic returns to the high frequency electric power source. By absorbing the harmonic in this manner, the standing wave due to the harmonic will be effectively prevented from being generated, and the density of plasma is made even.

1 . A plasma etching apparatus comprising:
 a chamber maintained at a reduced pressure;   a first electrode and a second electrode arranged to be opposed to each other in the chamber;   a process gas source connected to the chamber;   a first high frequency electric source connected to the first electrode; and   a direct current voltage source connected to the first electrode wherein plasma is generated by applying high frequency electric power from the first high frequency electric source to the first electrode, and   wherein a substrate to be processed which is supported by the second electrode is subject to plasma etching processing in a state where thicker plasma sheath is generated by applying direct current voltage from the direct current voltage source to the first electrode.   
     
     
         2 . A plasma etching apparatus according to  claim 1 , further comprising a harmonic absorbing member arranged to come into contact with one of an outer periphery and an outer face on an opposing face, which is opposed to the second electrode, of the first electrode,
 wherein the harmonic absorbing member absorbs a harmonic generated by the high frequency electric power applied by the high frequency electric source.   
     
     
         3 . A plasma etching apparatus according to  claim 2 , wherein the harmonic absorbing member is laminated harmonic absorbing members having frequency characteristics different from each other. 
     
     
         4 . A plasma etching apparatus according to  claim 2 , wherein the harmonic absorbing member has magnetic resonance loss effect. 
     
     
         5 . A plasma etching apparatus according to  claim 4 , wherein the harmonic absorbing member contains ferrite. 
     
     
         6 . A plasma etching apparatus according to  claim 1 , further comprising an electrode plate, the electrode plate comprising:
 an outer portion constituted by conductor or semiconductor, formed in a ring-shape; and   a central portion constituted by a dielectric member or a high resistance member with higher resistivity than that of the outer portion, formed in a disk-shape fitted to an inner circumference of the ring-shape of the outer portion.   
     
     
         7 . A plasma etching apparatus according to  claim 6 , wherein the central portion of the electrode plate is formed of the high resistance member and a skin depth δ expressed by the following formula (1) is larger than the central portion of the electrode plate thickness.
   δ=(2/ω Φ μ) 1/2 
 
 [where ω=2πf (f is frequency), Φ is conductivity, μ is magnetic permeability] 
 
     
     
         8 . A plasma etching apparatus according to  claim 6 , wherein both the outer portion and the central portion of the electrode plate are formed form silicon, and the outer portion having low resistivity and the central portion having high resistivity are formed by differentiating doping amounts of dopant into the outer portion and the central portion. 
     
     
         9 . A plasma etching apparatus according to  claim 8 , further comprising:
 an electrode plate formed of conductor or semiconductor provide on the side of an opposing face, which si opposed to the second electrode, of the first electrode; and   one of a dielectric member and a high resistance member having higher resistivity than that of the electrode plate provided so as to come in contact with a central portion of a non-opposing face, which is not opposed to the second electrode of the electrode plate.   
     
     
         10 . A plasma etching apparatus according to  claim 9 , where a skin depth δ expressed by the following formula (1) is large than the electrode plate in thickness.
   δ=(2/ω Φ μ) 1/2 
 
 [where ω=2πf (f is frequency), Φ is conductivity, μ is magnetic permeability] 
 
     
     
         11 . A plasma etching apparatus according to  claim 9 , wherein a diameter of one of the dielectric member and the high resistance member is 50-220 mm. 
     
     
         12 . A plasma etching apparatus according to  claim 9 , wherein resistivity of the electrode plate is 1-100 Ω-m. 
     
     
         13 . A plasma etching apparatus according to  claim 1 , further comprising an electrode plate formed of conductor or semiconductor which is provided on the side of an opposing face, which is opposed to the second electrode of the first electrode; and
 an insulating layer formed on the side of an opposing face, which is opposed to the second electrode of the first electrode.   
     
     
         14 . A plasma etching apparatus according to  claim 1 , further comprising:
 an electrode plate formed of conductor or semiconductor provided on the side of an opposing face which is opposed to the second electrode of the first electrode; and   a member having an electromagnetic wave absorbing effect provided so as to come in contact with a central portion of an non-opposing face which is not opposed to the second electrode of the electrode plate.   
     
     
         15 . A plasma etching apparatus according to  claim 1 , further comprising:
 an electric power supplying rod connected to a central portion of the side of a non-opposing face, which is not opposed to the second electrode of the first electrode, the electric supplying rod supplying the high frequency electric power supplied from the high frequency electric source,   a conductive cylindrical member arranged near the electric power supplying rod so as to enclose the electric power supplying rod the conductive cylindrical member being grounded; and   a conductive plate-like member electrically connected to the conductive cylindrical member and grounded.   
     
     
         16 . A plasma etching apparatus according to  claim 1 , further comprising:
 an electric power supplying rod connected to a position shifted from a center to an outer periphery of the side of a non-opposing face, which is not opposed to the second electrode of the first electrode, the electric power supplying rod supplying the high frequency electric power supplied from the high frequency electric source;   a conductive cylindrical member arranged near the electric power supplying rod so as to enclose the electric power supplying rode, the conductive cylindrical member being grounded;   a conductive plate-like member electrically connected to the conductive cylindrical member and grounded; and   phase adjusting means connected to the first electrode at one terminal and grounded at the other one terminal, for adjusting a phase voltage and current of the high frequency electric power supplied to the first electrode.   
     
     
         17 . A plasma etching apparatus according to  claim 16 , wherein the phase adjusting means is an LC circuit arranged on the side of the non-opposing face of the first electrode at an opposite position to a connected position of the electric power supplying rod with respect to a center of the non-opposing face.