Substrate cleaning method for removing oxide film

Abstract

It was found out that when radicals generated by plasma are fed to a treatment chamber via a plurality of holes ( 111 ) formed on a partition plate which separates a plasma-forming chamber ( 108 ) from the treatment chamber, and the radicals are mixed with a treatment gas which is separately fed to the treatment chamber, the excitation energy of the radicals is suppressed and thereby the substrate surface treatment at high Si-selectivity becomes possible, which makes it possible to conduct the surface treatment of removing native oxide film and organic matter without deteriorating the flatness of the substrate surface. The radicals in the plasma are fed to the treatment chamber via radical-passing holes ( 111 ) of a plasma-confinement electrode plate ( 110 ) for plasma separation, the treatment gas is fed to the treatment chamber ( 121 ) to be mixed with the radicals in the treatment chamber, and then the substrate surface is cleaned by the mixed atmosphere of the radicals and the treatment gas.

1 . A substrate cleaning apparatus comprising a plasma-forming chamber, a substrate-cleaning treatment chamber containing a substrate holder, and a plasma-confinement electrode plate partitioning the plasma-forming chamber from the substrate-cleaning treatment chamber, wherein:
 the plasma-forming chamber has therein a high-frequency applying electrode in a plate-shape extending in the lateral direction of the plasma-forming chamber in parallel with the plasma-confinement electrode, the high-frequency applying electrode has a plurality of through-holes formed, which penetrate from the front face to the rear face thereof, and a ratio of V 2 /V 1  is set in a range from 0.01 to 0.8, where V 1  is the total volume of the high-frequency applying electrode including the through-holes and V 2  is the total volume of the through-holes;   the plasma-confinement electrode has a plurality of radical feed holes formed on the face thereof for communicating the plasma-forming chamber with the substrate-cleaning treatment chamber;   the plasma-confinement electrode further has a plurality of treatment gas feed holes formed on the face thereof and apposed to at least a part of the radical feed holes; and   the plasma-confinement electrode is arranged so as to face a substrate-supporting face of the substrate holder, and is electrically grounded, the radical feed holes are arranged so as to allow a neutral radical in the plasma generated in the plasma-forming chamber to pass therethrough into the substrate-cleaning treatment chamber, while preventing charged particles such as ions in the plasma generated in the plasma-forming chamber from passing therethrough, the treatment gas is fed into the substrate-cleaning treatment chamber via the treatment gas feed holes, and both the radical and the treatment gas are fed from the face of the plasma-confinement electrode toward the face of the substrate placed on the substrate holder.   
     
     
         2 . A substrate cleaning apparatus according to  claim 1 , wherein the plasma-confinement electrode has a treatment gas feed passage which transversely passes through the plasma-confinement electrode in a direction partitioning the plasma-forming chamber from the substrate-cleaning treatment chamber, each of the plurality of treatment gas feed holes is connected with the treatment gas feed passage, and the treatment gas supplied to the treatment gas feed passage is fed into the substrate-cleaning treatment chamber via the treatment gas feed holes. 
     
     
         3 . A substrate cleaning method of cleaning an oxide film on the surface of a semiconductor substrate placed in a substrate-cleaning treatment chamber, the method comprising the steps of:
 exciting a plasma-forming gas containing HF to generate plasma in a plasma-forming chamber;   selectively feeding a radical in the plasma from the plasma-forming chamber to the treatment chamber via a plurality of plasma feed holes formed distributedly on the face of a plasma-confinement electrode partitioning the plasma-forming chamber from the substrate-cleaning treatment chamber;   feeding a treatment gas containing unexcited HF into the treatment chamber; and   conducting cleaning treatment of the oxide film on the surface of the semiconductor substrate by the mixed atmosphere of the radical and the treatment gas, fed into the treatment chamber, wherein   the treatment gas is fed into the substrate-cleaning treatment chamber from the face of the plasma-confinement electrode, in almost parallel with the radical feeding, via a plurality of treatment gas feed holes formed distributedly on the face of the plasma-confinement electrode and apposed to at least a part of the radical holes, and the HF fraction to the total gas flow rate of the plasma-forming gas is in a range from 0.2 to 1.0.   
     
     
         4 . A substrate cleaning method according to  claim 3 , wherein the semiconductor substrate is a Si substrate, and the Si substrate is cleaned by etching to remove the oxide film on the Si substrate. 
     
     
         5 . A method of forming a gate insulation film in a MOS structure, comprising the steps of:
 cleaning the surface of a Si substrate by the method of  claim 4 ;   moving the surface-cleaned Si substrate to an epitaxial chamber without exposing the Si substrate to atmospheric air to form an epitaxial layer on the surface-cleaned Si substrate in the epitaxial chamber;   moving the Si substrate having the epitaxial layer formed thereon to a sputtering chamber without exposing the Si substrate to atmospheric air to form a dielectric film by sputtering on the epitaxial layer; and   moving the Si substrate having the dielectric film formed thereon to an oxidation-nitrification chamber without exposing the Si substrate to atmospheric air to form the gate insulation film by oxidizing, nitrifying or oxynitrifying the dielectric film.   
     
     
         6 . A method of  claim 5 , wherein the dielectric film is made of the one selected from the group consisting of Hf, La, Ta, Al, W, Ti, Si and Ge, or an alloy thereof. 
     
     
         7 . A method of cleaning a substrate surface in a substrate cleaning apparatus including a plasma-forming chamber, a substrate-cleaning treatment chamber, and a plasma-confinement electrode plate partitioning the plasma-forming chamber from the substrate-cleaning treatment chamber, the method comprising the steps of:
 placing a plate-shape substrate facing the face of the plasma-confinement electrode plate in the substrate-cleaning treatment chamber;   feeding a neutral radical in the plasma generated in the plasma-forming chamber from the plasma chamber to the substrate-cleaning treatment chamber via a plurality of radical feed holes distributedly formed on the face of the electrically grounded plasma-confinement electrode plate for communicating the plasma-forming chamber with the substrate-cleaning treatment chamber, while preventing charged particles such as ions in the plasma from passing therethrough; and   feeding an unexcited treatment gas into the substrate-cleaning treatment chamber, wherein   a high-frequency applying electrode in a plate-shape extending in a lateral direction in the plasma-forming chamber applies high frequency power with a high-frequency power density ranging from 0.001 to 0.25 W/cm 2  to the plasma-forming chamber, the high-frequency applying electrode has a plurality of through-holes formed penetrating from the front face to the rear face thereof, and a ratio of V 2 /V 1  is set in a range from 0.01 to 0.8 (where V 1  is the total volume of the high-frequency applying electrode including the through-holes, and V 2  is the total volume of the through-holes); and   the feed of the treatment gas to the substrate-cleaning treatment chamber is done, in parallel with the radical feeding, through a plurality of treatment gas feed holes distributedly formed on the face of the plasma-confinement electrode so as to face the face of the substrate, apposed to at least a part of the radical feed holes.   
     
     
         8 . A method of cleaning a substrate surface according to  claim 7 , wherein an oxide film on the substrate surface is cleaned. 
     
     
         9 . A method of cleaning an oxide film on a substrate surface according to  claim 8 , which is a method of cleaning an oxide film on the surface of a group IV semiconductor material substrate, wherein plasma is generated by feeding a plasma-forming gas containing HF to the plasma-forming chamber, and the treatment gas contains HF. 
     
     
         10 . A method of cleaning an oxide film on a substrate surface according to  claim 9 , wherein the HF fraction to the total gas flow rate of the plasma-forming gas is in a range from 0.2 to 1.0. 
     
     
         11 . A method of cleaning a substrate surface according to  claim 10 , wherein the treatment gas is sole HF. 
     
     
         12 . A method of cleaning an oxide film on a substrate surface according to  claim 7 , wherein the plasma gas is fed to the plasma-forming chamber via a shower plate, the shower plate has an inner face facing the high-frequency applying electrode, and the plasma-forming gas is fed to the plasma-forming chamber via a plurality of plasma-forming gas feed holes distributedly formed on the inner face of the shower plate. 
     
     
         13 . A method of forming a gate insulation film in a MOS structure, comprising the steps of:
 cleaning an oxide film on the surface of a Si substrate by the method of  claim 9 ;   moving the surface-cleaned Si substrate to an epitaxial chamber without exposing the Si substrate to atmospheric air to form an epitaxial layer on the surface-cleaned Si substrate;   moving the Si substrate having the epitaxial layer formed thereon to a sputtering chamber without exposing the Si substrate to atmospheric air to form a dielectric film on the epitaxial layer by sputtering; and   moving the Si substrate having the dielectric film formed thereon to an oxidation-nitrification chamber without exposing the Si substrate to atmospheric air to form the gate insulation film by oxidizing, nitrifying or oxnitrifying the dielectric film.   
     
     
         14 . A method of forming a gate insulation film according to  claim 13 , wherein the dielectric film is made of the one selected from the group consisting of Hf, La, Ta, Al, W, Ti, Si and Ge, or an alloy thereof.