Plasma processing apparatus

Abstract

A plasma processing method for processing a target substrate uses a plasma processing apparatus which includes a vacuum evacuable processing vessel for accommodating the target substrate therein, a first electrode disposed in the processing vessel and connected to a first RF power supply for plasma generation and a second electrode disposed to face the first electrode. The method includes exciting a processing gas containing fluorocarbon in the processing vessel to generate a plasma while applying a negative DC voltage having an absolute value ranging from about 100 V to 1500 V or an RF power of a frequency lower than about 4 MHz to the second electrode. The target layer is etched by the plasma, thus forming recesses on the etching target layer based on the pattern of the resist layer.

What is claimed is: 
     
         1 . A plasma processing apparatus comprising:
 a vacuum evacuable processing vessel for accommodating a target substrate therein, the target substrate including at least a patterned resist layer, a silicon dioxide film disposed under the resist layer, and a base layer composed of a single crystalline layer or a silicon nitride film disposed under the silicon dioxide film;   a lower electrode disposed in the processing vessel for mounting the target substrate thereon;   an upper electrode disposed to face the lower electrode;   a plurality of gas holes formed in the upper electrode to supply a processing gas containing fluorocarbon gas into the processing vessel;   a first RF power supply connected to the lower electrode to apply thereto a first RF power of a first frequency for plasma generation;   a DC supply connected to the upper electrode to apply a DC voltage thereto;   a gas exhaust line connected to the processing vessel to exhaust an inside of the processing vessel; and   a control unit configured to control the following steps of:
 loading the target substrate into the processing vessel; 
 supplying the processing gas into the processing vessel; 
 generating a plasma of the processing gas in the processing vessel by applying to the lower electrode the first RF power; 
 applying a negative DC voltage from the DC supply to the upper electrode; and 
 etching the silicon dioxide film by the plasma by using the resist layer as an etching mask, thus forming recesses in the silicon dioxide film, 
 wherein the negative DC voltage has an absolute value ranging from 100 V to 900 V to obtain a high etching rate of the silicon dioxide film and a high etching selectivity of the silicon dioxide film against the base layer of the single crystalline layer or the silicon nitride film. 
   
     
     
         2 . The plasma processing apparatus of  claim 1 , further comprising:
 a second RF power supply connected to the lower electrode to apply thereto a second RF power of a second frequency for ion attraction.   
     
     
         3 . The plasma processing apparatus of  claim 1 , wherein the upper electrode is made of a silicon-containing material. 
     
     
         4 . The plasma processing apparatus of  claim 1 , wherein the fluorocarbon gas is C 4 F 8 , C 5 F 8 , C 4 F 6  or C 6 F 6 . 
     
     
         5 . A plasma processing apparatus comprising:
 a vacuum evacuable processing vessel for accommodating a target substrate therein, the target substrate including at least a patterned resist layer, a low-k insulating film disposed under the resist layer, and a base layer composed of one of a silicon carbide, a silicon nitride or a silicon carbonitride film disposed under the low-k insulating film;   a lower electrode disposed in the processing vessel for mounting the target substrate thereon;   an upper electrode disposed to face the lower electrode;   a plurality of gas holes formed in the upper electrode to supply a processing gas containing fluorocarbon gas into the processing vessel;   a first RF power supply connected to the lower electrode to apply thereto a first RF power of a first frequency for plasma generation;   a DC supply connected to the upper electrode to apply a DC voltage thereto;   a gas exhaust line connected to the processing vessel to exhaust an inside of the processing vessel; and   a control unit configured to control the following steps of:
 loading the target substrate into the processing vessel; 
 supplying the processing gas into the processing vessel; 
 generating a plasma of the processing gas in the processing vessel by applying to the lower electrode the first RF power; 
 applying a negative DC voltage from the DC supply to the upper electrode; and 
 etching the low-k insulating film by the plasma by using the resist layer as an etching mask, thus forming recesses in the low-k insulating film, 
 wherein the negative DC voltage has an absolute value not less than 1000 V to obtain a high etching rate of the low-k insulating film and an etching selectivity of about 5 or higher, the etching selectivity being an etching selectivity of the low-k insulating film against the base layer of one of the silicon carbide, the silicon nitride and the silicon carbonitride film, and 
 wherein the negative DC voltage has an absolute value not larger than 1500 V such that a ratio of an opening diameter of the recesses to an opening diameter of an initial pattern of the resist layer is not greater than 1.2. 
   
     
     
         6 . The plasma processing apparatus of  claim 5 , further comprising:
 a second RF power supply connected to the lower electrode to apply thereto a second RF power of a second frequency for ion attraction.   
     
     
         7 . The plasma processing apparatus of  claim 5 , wherein the upper electrode is made of a silicon-containing material. 
     
     
         8 . The plasma processing apparatus of  claim 5 , wherein the fluorocarbon gas is C 4 F 8 , C 5 F 8 , C 4 F 6  or C 6 F 6 .