Dry etching apparatus and method

Abstract

There is provided dry etching apparatus including a stage on which a wafer is placed, an antenna electrode, a high frequency power supply, a shower plate, and an RF bias power supply. Further, a bias path controller is provided on the side of the antenna electrode. The bias path controller resonates in series with the static reactance formed by the shower plate with respect to the frequency of the RF bias. Then, the bias path controller changes and grounds the impedance by the variable inductive reactance. With this mechanism, highly uniform etching can be achieved even if a shower plate of quartz is used for corrosive gases.

What is claimed is: 
     
         1 . A dry etching apparatus comprising:
 a placement unit which is located in a vacuum chamber capable of being evacuated and on which an object to be processed is placed;   an antenna electrode which is located opposite the placement unit and supplied with high frequency to ionize etching gas into a plasma introduced into the vacuum chamber;   a high frequency supply unit connected to the antenna electrode to supply high frequency to the antenna electrode;   an antenna electrode dielectric material located on the plasma side of the antenna electrode to discharge the gas into the vacuum chamber;   a pressure control unit for controlling the pressure of the gas introduced into the vacuum chamber; and   an RF bias application unit for applying an RF bias to the placement unit,   wherein a bias path controller is provided on the side of the antenna electrode,   wherein the bias path controller resonates in series with a static reactance formed by the antenna electrode dielectric material with respect to the frequency of the RF bias,   wherein the bias path controller changes and grounds the impedance by a variable inductive reactance.   
     
     
         2 . The dry etching apparatus according to  claim 1 , further comprising a plasma distribution adjustment unit including a plurality of electromagnets. 
     
     
         3 . The dry etching apparatus according to  claim 1 ,
 wherein the bias path controller includes an antenna RF bias current detection unit and a variable reactance automatic matching unit,   wherein the variable reactance automatic matching unit is synchronized with a time modulated signal from the RF bias.   
     
     
         4 . The dry etching apparatus according to  claim 1 ,
 wherein the dry etching apparatus includes a bias distribution control unit,   wherein the bias distribution control unit changes the impedance of the bias path controller, by using a current value from a total RF bias current detection unit located on the side of the RF bias application unit, and using a current value from the antenna RF bias current detection unit.   
     
     
         5 . The dry etching apparatus according to  claim 2 ,
 wherein the dry etching apparatus includes a bias distribution control unit,   wherein the bias distribution control unit changes the current values of the electromagnets, by using a current value from a total RF bias current detection unit located on the side of the RF bias application unit, and using a current value from the antenna RF bias current detection unit.   
     
     
         6 . The dry etching apparatus according to  claim 1 ,
 wherein the vacuum chamber includes an insulating inner wall in the side wall portion between the antenna electrode and the placement unit.   
     
     
         7 . The dry etching apparatus according to  claim 6 ,
 wherein the insulating inner wall is partially covered by a folded earth part.   
     
     
         8 . The dry etching apparatus according to  claim 6 ,
 wherein the vacuum chamber includes the bias path controller on the side wall side.   
     
     
         9 . A dry etching method comprising the steps of:
 placing an object to be processed on a stage;   introducing etching gas into a vacuum chamber in which the stage is placed;   controlling the pressure of the gas introduced into the vacuum chamber;   supplying high frequency to an antenna electrode disposed opposite the objet to be processed to ionize the gas into a plasma; and   applying an RF bias to the object to be processed,   wherein the dry etching method further includes an RF bias current ratio control step for controlling the ratio of the RF bias current flowing to the antenna electrode and the RF bias current flowing to the side of the side wall of the vacuum chamber.   
     
     
         10 . The dry etching method according to  claim 9 ,
 wherein the RF bias current ratio control step includes a step of controlling the impedance on the antenna side.   
     
     
         11 . The dry etching method according to  claim 10 ,
 wherein the step of controlling the impedance on the antenna side includes the steps of:   changing and grounding the impedance to the frequency of the RF bias by a bias path controller located on the side of the antenna electrode; and   detecting the total current of the RF bias as well as the current flowing to the antenna electrode, and adjusting the bias path controller so that the change in the current is within the allowable value during plasma processing.   
     
     
         12 . The dry etching method according to  claim 9 ,
 wherein the RF bias current ratio control step includes a step of controlling the distribution of the plasma by using a plurality of electromagnets.   
     
     
         13 . The dry etching method according to  claim 12 ,
 wherein the step of controlling the distribution of the plasma includes a step of detecting the total current of the RF bias as well as the current following to the antenna electrode, and adjusting the ratio of the current to the electromagnets so that the change in the current is within the allowable value during plasma processing.   
     
     
         14 . The dry etching method according to  claim 10 ,
 wherein the RF bias current ratio control step includes a step of controlling the impedance on the side of the side wall of the vacuum chamber.