Plasma etching apparatus

Abstract

A plasma etching apparatus of an electrodeless system can uniformize a radical density, and improve the uniformity of etching. The plasma etching apparatus of the electrodeless system includes a decompression chamber, a gas supply mechanism, a dielectric window, a plasma generation unit, a stage on which a sample is placed, and a first RF power supply connected to the stage. The plasma etching apparatus further includes a gas introduction mechanism for supplying a second gas, and a second RF power supply for inputting a RF power that allows radicals to be generated in an outer periphery of the sample.

What is claimed is: 
     
         1 . A plasma etching apparatus that has a first gas introduction mechanism for supplying a first gas into a decompression chamber, generates plasma by inputting electromagnetic waves from an external of the decompression chamber into the decompression chamber through a dielectric window, generates radicals from the first gas by the plasma, irradiates a sample placed on a stage with the radicals, and inputs a RF power from a first RF power supply connected to the stage to generate a bias voltage in the sample for etching, the plasma etching apparatus comprising:
 a second gas introduction mechanism for supplying a second gas aside from the first gas introduction mechanism; and   a second RF power supply for inputting the stage the RF power that allows the radicals to be generated in the outer periphery of the sample, which is different in frequency from the first RF power supply.   
     
     
         2 . The plasma etching apparatus according to  claim 1 ,
 wherein the second gas is supplied from a position within 1/5 of a diameter of the sample from an outermost periphery of the sample.   
     
     
         3 . The plasma etching apparatus according to  claim 1 ,
 wherein the frequency of the second RF power supply is 4 MHz or higher, and the frequency of the first RF power supply is lower than the frequency of the second RF power supply.   
     
     
         4 . The plasma etching apparatus according to  claim 1 ,
 wherein the electromagnetic waves are microwaves, and a solenoid coil for generating a magnetic field within the decompression chamber is provided.   
     
     
         5 . The plasma etching apparatus according to  claim 1 ,
 wherein a ring made of a dielectric material is disposed in an outer periphery of the stage, and introduction holes of the second gas are formed in the ring.   
     
     
         6 . The plasma etching apparatus according to  claim 3 ,
 wherein a ring made of a dielectric material is disposed at an outer periphery of the stage, and introduction holes of the second gas are formed in the ring.   
     
     
         7 . The plasma etching apparatus according to  claim 5 ,
 wherein the introduction holes of the second gas are connected each other and formed a circumferential slit in the ring.   
     
     
         8 . The plasma etching apparatus according to  claim 5 ,
 wherein the introduction holes of the second gas are arranged at a pitch a along the ring, and at a distance b from the outermost periphery of the sample, and a/b is 1 or lower.   
     
     
         9 . The plasma etching apparatus according to  claim 5 ,
 wherein the introduction holes of the second gas are arranged so that the distance from the outermost periphery of the sample is b, and a distance from the dielectric window is c, and b/(b+c) is 0.5 or lower.   
     
     
         10 . The plasma etching apparatus according to  claim 1 ,
 wherein the second gas is oxygen gas or fluorocarbon gas.   
     
     
         11 . A plasma etching apparatus that has a first gas introduction mechanism for supplying a first gas into a decompression chamber, generates plasma by inputting electromagnetic waves from an external of the decompression chamber into the decompression chamber through a dielectric window, generates radicals from the first gas by the plasma, irradiates a sample placed on a stage with the radicals, and inputs a RF power from a first RF power supply connected to the stage to generate a bias voltage in the sample for etching, the plasma etching apparatus comprising:
 a second gas introduction mechanism for supplying a second gas aside from the first gas introduction mechanism;   an electrode disposed in an outer periphery of the sample so as to be isolated from the stage; and   a second RF power supply for inputting the RF power that allows the radicals to be generated in the outer periphery of the sample to the electrode, which is different in frequency from the first RF power supply.   
     
     
         12 . The plasma etching apparatus according to claim wherein the second gas is supplied from a position within 1/5 of a diameter of the sample from an outermost periphery of the sample.