Substrate-processing method and method of manufacturing electronic device

Abstract

A method of manufacturing an electronic device includes dipping a substrate in a solution containing sulfuric acid, which is accommodated in a processing vessel. An aqueous solution of hydrogen peroxide supplies the sulfuric acid accommodated in the processing vessel for generating peroxomonosulfuric acid (Caro's acid). Therefore, an organic material present on the surface of the substrate is removed by the action of Caro's acid within the processing vessel. The time for supplying the aqueous solution of hydrogen peroxide into the processing vessel is set on the basis of the change with time in the concentration of Caro's acid measured in advance so as to permit the peak in the concentration of Caro's acid to appear while the substrate is kept dipped in the processing solution.

1 . A method of processing a substrate, comprising:
 measuring a prescribed number of times the absorbance of a mixed liquid material containing sulfuric acid, hydrogen peroxide and an oxidizing material produced by reacting between sulfuric acid and hydrogen peroxide during the process of mixing sulfuric acid and hydrogen peroxide;   detecting the concentration of the oxidizing material in the mixed liquid material, the concentration corresponding to the absorbance, thereby obtaining the relationship between the absorbance and the concentration of the oxidizing material;   measuring the absorbance of the mixed liquid material at a plurality of timings during the process of mixing sulfuric acid and hydrogen peroxide;   checking the absorbance of the mixed liquid material measured at each timing with the relationship between the absorbance and the concentration of the oxidizing material so as to estimate in advance the change with time in the concentration of the oxidizing material in the mixed liquid material during the mixing process; and   processing a substrate with a processing solution consisting of the mixed liquid material containing the oxidizing material produced by reacting between sulfuric acid and hydrogen peroxide, wherein the processing of the substrate with the processing solution is controlled based on the estimated change with time in the concentration of the oxidizing material contained in the mixed liquid material so as to permit the peak in the concentration of the oxidizing material in the processing solution to appear during the processing of the substrate with the processing solution.   
   
   
       2 . The method according to  claim 1 , wherein the processing of the substrate with the processing solution is performed for removing an organic material present on the substrate to be processed. 
   
   
       3 . The method according to  claim 1 , wherein the oxidizing material is formed of peroxomonosulfuric acid. 
   
   
       4 . The method according to  claim 1 , wherein the absorbance of the mixed liquid material containing sulfuric acid and hydrogen peroxide is measured by capillary zone electrophoretic analysis. 
   
   
       5 . The method according to  claim 1 , wherein each of timings for measuring the absorbance comprises period of before and after the dipping of the substrate to be processed in the mixed liquid material and period at which the substrate is kept dipped in the mixed liquid material. 
   
   
       6 . A method of processing a substrate, comprising:
 measuring a prescribed number of times the absorbance of a mixed liquid material containing sulfuric acid, hydrogen peroxide and an oxidizing material produced by reacting between sulfuric acid and hydrogen peroxide during the process of supplying sulfuric acid and hydrogen peroxide into a processing vessel and mixing between sulfuric acid and hydrogen peroxide in the processing vessel;   detecting the concentration of the oxidizing material in the mixed liquid material, the concentration corresponding to the absorbance, thereby obtaining the relationship between the absorbance and the concentration of the oxidizing material;   measuring the absorbance of the mixed liquid material at a plurality of timings during the process of supplying sulfuric acid and hydrogen peroxide into the processing vessel and mixing sulfuric acid and hydrogen peroxide in the processing vessel;   checking the absorbance of the mixed liquid material measured at each timing with the relationship between the absorbance and the concentration of the oxidizing material so as to estimate in advance the change with time in the concentration of the oxidizing material in the mixed liquid material during the mixing process;   accommodating in the processing vessel a processing solution consisting of the mixed liquid material containing sulfuric acid, hydrogen peroxide and the oxidizing material produced by reacting between sulfuric acid and hydrogen peroxide during the process of supplying sulfuric acid and hydrogen peroxide into the processing vessel and mixing between sulfuric acid and hydrogen peroxide in the processing vessel; and   dipping a substrate to be processed in the processing solution for processing the substrate, wherein the processing of the substrate with the processing solution is controlled based on the estimated change with time in the concentration of the oxidizing material contained in the processing solution so as to permit the peak in the concentration of the oxidizing material in the processing solution to appear during the processing of the substrate with the processing solution.   
   
   
       7 . The method according to  claim 6 , wherein the processing of the substrate with the processing solution is performed for removing an organic material present on the substrate to be processed. 
   
   
       8 . The method according to  claim 6 , wherein the oxidizing material is formed of peroxomonosulfuric acid. 
   
   
       9 . The method according to  claim 6 , wherein the absorbance of the mixed liquid material containing sulfuric acid and hydrogen peroxide is measured by capillary zone electrophoretic analysis. 
   
   
       10 . The method according to  claim 6 , wherein each of timings for measuring the absorbance comprises period of before and after the dipping of the substrate to be processed in the mixed liquid material and period at which the substrate is kept dipped in the mixed liquid material. 
   
   
       11 . A method of manufacturing an electronic device, comprising:
 estimating in advance the change with time in the concentration of an oxidizing material contained in a mixed liquid material and produced during the mixing process between sulfuric acid and hydrogen peroxide, wherein the estimating process includes the steps of:
 (a) measuring a prescribed number of times the absorbance of the mixed liquid material containing sulfuric acid, hydrogen peroxide and the oxidizing material produced by reacting between sulfuric acid and hydrogen peroxide, wherein the absorbance is measured during the process of mixing sulfuric acid with hydrogen peroxide, 
 (b) detecting the concentration of the oxidizing material in the mixed liquid material, the concentration corresponding to the absorbance, so as to obtain the relationship between the absorbance and the concentration of the oxidizing material, 
 (c) measuring the absorbance of the mixed liquid material at a plurality of timings during the process of mixing sulfuric acid with hydrogen peroxide, and 
 (d) checking the absorbance of the mixed liquid material measured at each timing with the relationship between the absorbance and the concentration of the oxidizing material; 
   forming a pattern of an organic material on a film to be processed;   processing the film to be processed by using the pattern of the organic material as a mask; and   processing the substrate having the pattern of the organic material formed thereon with a processing solution consisting of a mixed liquid material containing sulfuric acid, hydrogen peroxide and the oxidizing material produced by reacting between sulfuric acid and hydrogen peroxide, wherein the processing of the substrate with the processing solution is controlled based on the estimated change with time in the concentration of the oxidizing material contained in the mixed solution so as to permit the peak in the concentration of the oxidizing material in the processing solution to appear during the processing of the substrate with the processing solution.   
   
   
       12 . The method according to  claim 11 , wherein the oxidizing material is formed of peroxomonosulfuric acid. 
   
   
       13 . The method according to  claim 11 , wherein the concentration of the oxidizing material is detected by capillary zone electrophoretic analysis. 
   
   
       14 . The method according to  claim 11 , wherein each of timings for measuring the absorbance comprises period of before and after the dipping of the substrate having the pattern of the organic material formed thereon in the mixed liquid material and period at which the substrate is kept dipped in the mixed liquid material. 
   
   
       15 . A method of manufacturing an electronic device, comprising:
 estimating in advance the change with time in the concentration of peroxomonosulfuric acid in a mixed liquid material containing sulfuric acid, hydrogen peroxide and peroxomonosulfuric acid, wherein the estimating process includes the steps of:
 (a) sampling a mixed liquid material containing sulfuric acid, hydrogen peroxide and peroxomonosulfuric acid produced by reacting between sulfuric acid and hydrogen peroxide in a processing vessel during the process of supplying hydrogen peroxide into the processing vessel having a sulfuric acid-containing solution accommodated therein for forming peroxomonosulfuric acid, and 
 (b) detecting hydrogen peroxide and sulfuric acid contained in the sampled mixed liquid material by capillary zone electrophoretic analysis, 
   forming a film to be processed on a substrate;   forming a pattern of an organic material on the film to be processed;   processing the film to be processed by using the pattern of the organic material as a mask; and   supplying an aqueous solution of hydrogen peroxide into the processing vessel accommodating a solution containing sulfuric acid;   dipping the substrate having the pattern of the organic material formed thereon in the solution accommodated in the processing vessel; and   setting the supplying time of the aqueous solution of the hydrogen peroxide into the processing vessel based on the estimated change with time in the concentration of the peroxomonosulfuric acid so as to permit the peak in the concentration of the peroxomonosulfuric acid to appear while the substrate is kept dipped in the solution accommodated in the processing vessel, thereby removing the organic film.   
   
   
       16 . The method according to  claim 15 , wherein the supplying time of the aqueous solution of hydrogen peroxide into the processing vessel is set to permit the peak in the concentration of the peroxomonosulfuric acid to appear when the time as counted from the insertion of the substrate into the processing vessel falls within a period of 40 to 60% of the period between the insertion of the substrate bearing the organic material into the processing vessel and the withdrawal of the substrate out of the processing vessel. 
   
   
       17 . The method according to  claim 15 , wherein each of timings for sampling the mixed liquid material comprises period of before and after the dipping of the substrate having the pattern of the organic material formed thereon in the mixed liquid material and period at which the substrate is kept dipped in the mixed liquid material.