Plasma processing-apparatus processing object support platform, plasma processing apparatus, and plasma processing method

Abstract

According to one embodiment, a plasma processing-apparatus processing object support platform includes a lower plate, an upper plate, and a variable condenser. The lower plate is electrically conductive. The upper plate is provided on the lower plate. A processing object is placed on an upper surface of the upper plate. The variable condenser is provided along a circumferential direction of the lower plate in a region at an upper outer circumferential vicinity of the lower plate. The region has an annular configuration. The variable condenser includes a first capacitance element and a second capacitance element disposed respectively on an inner circumferential side and an outer circumferential side in the region having the annular configuration. Mutually-different control voltages are suppliable to the first capacitance element and the second capacitance element.

What is claimed is: 
     
         1 . A plasma processing-apparatus processing object support platform, comprising:
 a lower plate, the lower plate being electrically conductive;   an upper plate provided on the lower plate, a processing object being placed on an upper surface of the upper plate; and   a variable condenser provided along a circumferential direction of the lower plate in a region at an upper outer circumferential vicinity of the lower plate, the region having an annular configuration, the variable condenser including a first capacitance element and a second capacitance element disposed respectively on an inner circumferential side and an outer circumferential side in the region having the annular configuration, mutually-different control voltages being suppliable to the first capacitance element and the second capacitance element.   
     
     
         2 . The support platform according to  claim 1 , wherein the variable condenser includes a plurality of the first capacitance elements disposed on the inner circumferential side in the region having the annular configuration, and a plurality of the second capacitance elements disposed on the outer circumferential side in the region having the annular configuration, a set of the first capacitance element and the second capacitance element being multiply arranged along the circumferential direction. 
     
     
         3 . The support platform according to  claim 1 , wherein
 the variable condenser includes a pair of counter electrodes, and a variable capacitance unit held between the pair of counter electrodes, and   the variable condenser is disposed to have an orientation in which one of the pair of counter electrodes is on a lower side and the other of the pair of counter electrodes is on an upper side.   
     
     
         4 . The support platform according to  claim 3 , wherein the control voltage is supplied between the pair of counter electrodes. 
     
     
         5 . The support platform according to  claim 3 , wherein the variable condenser further includes a pair of control electrodes provided at positions not interfering with the pair of counter electrodes. 
     
     
         6 . The support platform according to  claim 5 , wherein
 a prescribed bias voltage is supplied between the pair of counter electrodes, and   the control voltage is supplied between the pair of control electrodes.   
     
     
         7 . The support platform according to  claim 3 , wherein the variable capacitance unit is a p-n junction-type diode. 
     
     
         8 . The support platform according to  claim 3 , wherein the variable capacitance unit is a ferroelectric. 
     
     
         9 . The support platform according to  claim 1 , wherein
 the lower plate includes an upper portion, a lower portion, and a stepped portion between the upper portion and the lower portion, the upper portion being positioned on the upper plate side and having substantially the same outer diameter as the upper plate, the lower portion having a larger outer diameter than the upper portion, and   the variable condenser is disposed at the stepped portion of the lower plate.   
     
     
         10 . A plasma processing apparatus, comprising:
 the plasma processing-apparatus processing object support platform according to  claim 1 ;   a gas supply unit arranged to oppose the processing object support platform;   a chamber housing the processing object support platform and the gas supply unit; and   a RF power supply supplying electrical power to the lower plate of the processing object support platform.   
     
     
         11 . A plasma processing-apparatus processing object support platform, comprising:
 a lower plate, the lower plate being electrically conductive;   an upper plate provided on the lower plate, a processing object being placed on an upper surface of the upper plate; and   a variable condenser provided along a circumferential direction of the lower plate in a region at an upper outer circumferential vicinity of the lower plate, the region having an annular configuration, the variable condenser including at least two capacitance elements along the circumferential direction in the region having the annular configuration, mutually-different control voltages being suppliable respectively to the capacitance elements.   
     
     
         12 . The support platform according to  claim 11 , wherein
 the variable condenser includes a pair of counter electrodes, and a variable capacitance unit held between the pair of counter electrodes, and   the variable condenser is disposed to have an orientation in which one of the pair of counter electrodes is on a lower side and the other of the pair of counter electrodes is on an upper side.   
     
     
         13 . The support platform according to  claim 12 , wherein the control voltage is supplied between the pair of counter electrodes. 
     
     
         14 . The support platform according to  claim 12 , wherein the variable condenser further includes a pair of control electrodes provided at positions not interfering with the pair of counter electrodes. 
     
     
         15 . The support platform according to  claim 14 , wherein
 a prescribed bias voltage is supplied between the pair of counter electrodes, and   the control voltage is supplied between the pair of control electrodes.   
     
     
         16 . The support platform according to  claim 12 , wherein the variable capacitance unit is a p-n junction-type diode. 
     
     
         17 . The support platform according to  claim 12 , wherein the variable capacitance unit is a ferroelectric. 
     
     
         18 . The support platform according to  claim 11 , wherein
 the lower plate includes an upper portion, a lower portion, and a stepped portion between the upper portion and the lower portion, the upper portion being positioned on the upper plate side and having substantially the same outer diameter as the upper plate, the lower portion having a larger outer diameter than the upper portion, and   the variable condenser is disposed at the stepped portion of the lower plate.   
     
     
         19 . A plasma processing apparatus, comprising:
 the plasma processing-apparatus processing object support platform according to  claim 11 ;   a gas supply unit arranged to oppose the processing object support platform;   a chamber housing the processing object support platform and the gas supply unit; and   a RF power supply supplying electrical power to the lower plate of the processing object support platform.   
     
     
         20 . A plasma processing method, comprising:
 placing a processing object on an upper plate of a processing object support platform while placing an edge ring above a variable condenser of the processing object support platform, the processing object support platform including a lower plate, the upper plate, and the variable condenser, the lower plate being electrically conductive, the upper plate being provided on the lower plate, the processing object being placed on an upper surface of the upper plate, the variable condenser being provided along an outer circumference of the lower plate in a region at an upper outer circumferential vicinity of the lower plate, the region having an annular configuration, the variable condenser including a first capacitance element and a second capacitance element disposed respectively on an inner circumferential side and an outer circumferential side in the region having the annular configuration, mutually-different control voltages being suppliable to the first capacitance element and the second capacitance element; and   supplying a processing gas from a gas supply unit arranged to oppose the processing object support platform inside a chamber, and generating plasma in a space above the processing object and the edge ring,   processing of a second processing object being implemented after implementing processing of a first processing object,   the processing of the first processing object being implemented by generating plasma in the space in a state in which the first processing object is placed on the upper plate of the processing object support platform while the edge ring is placed above the variable condenser of the processing object support platform, and a capacitance of the variable condenser is set to a first value,   the processing of the second processing object being implemented by generating plasma in the space in a state in which the second processing object is placed on the upper plate of the processing object support platform with the edge ring still placed above the variable condenser of the processing object support platform, and the capacitance of the variable condenser is set to a second value greater than the first value.