Dry Ashing by Secondary Excitation

Abstract

An ashing process and device forms radicals of an ashing gas through a secondary reaction. A plasma is generated from a first gas, which is diffused through a first gas distribution plate (GDP). The plasma is diffused through a second GDP and a second gas is supplied below the second GDP. The first gas reacts with the second gas to energize the second gas. The energized second gas is used in ashing a resist layer from a substrate.

What is claimed is: 
     
         1 . An apparatus comprising:
 a plasma source generator configured to generate a plasma from a first gas in a first chamber;   a first gas source configured to provide the first gas to the first chamber;   a first gas distribution plate (GDP) interposed between the first chamber and a second chamber, the first GDP configured to limit plasma from the first chamber to the second chamber;   a second GDP interposed between the second chamber and a third chamber, the second GDP comprising first holes, the first holes being through holes;   a second gas source configured to provide a second gas to the third chamber; and   a pedestal disposed in the third chamber, the pedestal configured to retain a wafer.   
     
     
         2 . The apparatus of  claim 1 , wherein the pedestal is configured to move the wafer up or down. 
     
     
         3 . The apparatus of  claim 1 , wherein the second GDP comprises a plurality of gas supply holes formed in a bottom of the second GDP, wherein the second gas source is coupled to the plurality of gas supply holes. 
     
     
         4 . The apparatus of  claim 3 , wherein the first holes have a first width and the gas supply holes have a second width, the second width being smaller than the first width. 
     
     
         5 . The apparatus of  claim 1 , wherein a distance between the first GDP and the second GDP is configured by vertically moving the first GDP or the second GDP. 
     
     
         6 . The apparatus of  claim 1 , wherein the first GDP and the second GDP are grounded. 
     
     
         7 . The apparatus of  claim 1 , wherein the pedestal is configured to retain the wafer while radicals of the first gas energize the second gas to form radicals of the second gas, wherein the radicals of the second gas alter a surface of the wafer. 
     
     
         8 . The apparatus of  claim 1 , wherein sidewalls of the first holes of the second GDP are anti-perpendicular to an upper surface of the second GDP. 
     
     
         9 . The apparatus of  claim 8 , wherein an opening of each of the first holes at the upper surface of the second GDP are larger than a corresponding opening of each of the first holes at a lower surface of the second GDP, wherein the upper surface corresponds to a bottom of the second chamber and the lower surface corresponds to a top of the third chamber. 
     
     
         10 . An apparatus comprising:
 a plasma source generator configured to generate a plasma from a first gas;   a first gas distribution plate (GDP) interposed between the plasma source generator and a process chamber, the first GDP comprising first holes configured to limit plasma from the plasma source generator to the process chamber, the first GDP comprising second holes configured to provide a second gas to the process chamber, the second holes interspersed among the first holes;   a second gas source coupled to the second holes, configured to provide the second gas; and   a pedestal disposed in the process chamber, the pedestal configured to retain a wafer.   
     
     
         11 . The apparatus of  claim 10 , wherein the second holes have an upper opening which is interposed between an upper surface of the first GDP and a lower surface of the first GDP. 
     
     
         12 . The apparatus of  claim 10 , wherein sidewalls of the first holes of the first GDP are non-vertical. 
     
     
         13 . The apparatus of  claim 12 , wherein each of the first holes are funnel shaped, having a larger top opening than bottom opening. 
     
     
         14 . The apparatus of  claim 10 , wherein a width of each of the second holes are smaller than a width of each of the first holes. 
     
     
         15 . The apparatus of  claim 10 , further comprising a first gas channel and a second gas channel, each of which are interposed in the first GDP between an upper surface of the first GDP and a lower surface of the first GDP, wherein the first gas channel is parallel to the second gas channel, wherein the second holes are coupled to the first gas channel, wherein the first gas channel and the second gas channel are coupled to the second gas source. 
     
     
         16 . The apparatus of  claim 10 , configured to generate a plasma from the first gas while radicals of the first gas energize the second gas to form radicals of the second gas, wherein the radicals of the second gas remove a material layer from the wafer. 
     
     
         17 . A device comprising:
 a first chamber;   a second chamber;   a third chamber;   a plasma generator, the plasma generator configured to generate radicals of a first gas in the first chamber;   a first plate between the first chamber and the second chamber, the first plate comprising a first plurality of through holes formed therein, the first plate configured to restrict a first portion of the radicals of the first gas from entering the second chamber;   a second plate between the second chamber and the third chamber, the second plate comprising a second plurality of through holes formed therein, the second plate configured to restrict a second portion of the radicals of the first gas from entering the third chamber; and   a pedestal, wherein the pedestal is configured to retain a wafer.   
     
     
         18 . The device of  claim 17 , wherein the second plate further comprises a plurality of gas supply holes formed in a bottom surface of the second plate, the gas supply holes configured to supply a second gas to the third chamber. 
     
     
         19 . The device of  claim 18 , wherein the gas supply holes are configured to supply the second gas to the third chamber while the radicals of the first gas enter the third chamber by the second plurality of through holes, wherein when the radicals of the first gas interact with the second gas a penning ionization occurs to create radicals of the second gas, the radicals of the second gas contacting the wafer. 
     
     
         20 . The device of  claim 17 , wherein the each of first plurality of through holes or each of the second plurality of through holes have a first sidewalls and a second sidewall, wherein the first sidewall is anti-parallel to the second sidewall.