Method and apparatus for stable plasma processing

Abstract

A method and apparatus for etching a substrate using a spatially modified plasma is provided herein. In one embodiment, the method includes providing a process chamber having a plasma stabilizer disposed above a substrate support pedestal. A substrate is placed upon the pedestal. A process gas is introduced into the process chamber and a plasma is formed from the process gas. The substrate is etched with a plasma having an ion density to radical density ratio defined by the plasma stabilizer.

1 . An apparatus for plasma processing a substrate, comprising:
 a plasma processing chamber;   a substrate support pedestal disposed in the plasma processing chamber;   an inductive antenna for forming a plasma within the plasma processing chamber;   a plasma stabilizer member disposed in the plasma processing chamber above the substrate support pedestal, the plasma stabilizer member electrically isolated from the plasma processing chamber and having a diameter greater than a diameter of the pedestal and a plurality of apertures formed through the member; and   a plurality of support legs supporting the plasma stabilizer member above the substrate support pedestal; and   an edge ring disposed on the substrate support pedestal and having the plurality of support legs extending from the edge ring, wherein the plasma stabilizer member is secured to the edge ring.   
     
     
         2 . The apparatus of  claim 1 , wherein the antenna inductively couples RF power to the plasma processing chamber. 
     
     
         3 . The apparatus of  claim 1 , wherein the plasma stabilizer member is disposed about 1.25 cm below a ceiling of the plasma processing chamber. 
     
     
         4 . The apparatus of  claim 1 , wherein the plurality of apertures is arranged in a square grid pattern. 
     
     
         5 . The apparatus of  claim 1 , wherein the apertures are about 1.25 cm in diameter. 
     
     
         6 . The apparatus of  claim 1 , wherein the plasma stabilizer member is non-parallel to the upper surface of the substrate support pedestal. 
     
     
         7 . The apparatus of  claim 1 , wherein the apertures have a hole size, shape, position, and distribution over the surface of the plasma stabilizer member to define an ion density to radical density ratio proximate the substrate support pedestal. 
     
     
         8 . The apparatus of  claim 1 , wherein the edge ring is disposed about an upper portion of the substrate support pedestal. 
     
     
         9 . The apparatus of  claim 1 , wherein the legs support the plasma stabilizer member in a substantially parallel, spaced apart relation with respect to the substrate support pedestal. 
     
     
         10 . The apparatus of  claim 1 , wherein the plasma stabilizer member is fabricated from at least one of ceramic, quartz, or anodized aluminum. 
     
     
         11 . The apparatus of  claim 1 , wherein the plasma stabilizer member is electrically isolated from ground. 
     
     
         12 . The apparatus of  claim 1 , wherein the plasma stabilizer member is operable to form a plasma having an ion density to radical density ratio in a first region above the plasma stabilizer member that is different from the ion density to radical density in a second region below the plasma stabilizer member. 
     
     
         13 . The apparatus of  claim 12 , wherein the ion density to radical density ratio is lower in the second region. 
     
     
         14 . An apparatus for plasma etching, comprising:
 a process chamber;   a substrate support disposed in the process chamber, wherein the substrate support comprises an edge ring;   an inductive antenna for forming a plasma within the process chamber;   a member secured to the edge ring and having a diameter greater than a diameter of the substrate support and a plurality of apertures, wherein the member is electrically isolated from the process chamber; and   a plurality of support legs extending from the edge ring and maintaining the member in a spaced apart relation to the substrate support.   
     
     
         15 . The apparatus of  claim 14 , wherein the antenna inductively couples RF power to the process chamber. 
     
     
         16 . The apparatus of  claim 14 , wherein the plurality of apertures comprises a first group of apertures arranged in a first aperture density and a second group of apertures arranged in a second aperture density that is different than the first aperture density. 
     
     
         17 . The apparatus of  claim 15 , wherein the legs maintain the member in a substantially parallel relation with respect to the substrate support. 
     
     
         18 . The apparatus of  claim 16 , wherein the plasma has an ion density to radical density ratio in a first region above the member that is different from the ion density to radical density in a second region below the member. 
     
     
         19 . The apparatus of  claim 17 , wherein the member is fabricated from at least one of ceramic, quartz, or anodized aluminum. 
     
     
         20 . The apparatus of  claim 18 , wherein the apertures are arranged in a square grid pattern.