Processing of semiconductor components with dense processing fluids and ultrasonic energy

Abstract

Method for processing an article with a dense processing fluid in a processing chamber while applying ultrasonic energy during processing. The dense fluid may be generated in a separate pressurization vessel and transferred to the processing chamber, or alternatively may be generated directly in the processing chamber. A processing agent may be added to the pressurization vessel, to the processing chamber, or to the dense fluid during transfer from the pressurization vessel to the processing chamber. The ultrasonic energy may be generated continuously at a constant frequency or at variable frequencies. Alternatively, the ultrasonic energy may be generated intermittently.

1 . A method for processing an article comprising: 
 (a) introducing the article into a sealable processing chamber and sealing the processing chamber;    (b) preparing a dense fluid by: 
 (b1) introducing a subcritical fluid into a pressurization vessel and isolating the vessel; and  
 (b2) heating the subcritical fluid at essentially constant volume and essentially constant density to yield a dense fluid;  
   (c) transferring at least a portion of the dense fluid from the pressurization vessel to the processing chamber, wherein the transfer of the dense fluid is driven by the difference between the pressure in the pressurization vessel and the pressure in the processing chamber, thereby pressurizing the processing chamber with transferred dense fluid;    (d) introducing one or more processing agents into the processing chamber either before (c), or during (c), or after (c) to provide a dense processing fluid;    (e) introducing ultrasonic energy into the processing chamber and contacting the article with the dense processing fluid to yield a spent dense processing fluid and a treated article; and    (f) separating the spent dense processing fluid from the treated article.    
     
     
         2 . The method of  claim 1  wherein the dense fluid is generated in (b2) at a reduced temperature in the pressurization vessel below about 1.8, wherein the reduced temperature is defined as the average absolute temperature of the dense fluid in the pressurization vessel after heating divided by the absolute critical temperature of the fluid.  
     
     
         3 . The method of  claim 2  wherein the contacting of the article with the dense processing fluid in the processing chamber in (d) is effected at a reduced temperature in the processing chamber between about 0.8 and about 1.8, wherein the reduced temperature is defined as the average absolute temperature of the dense processing fluid in the processing chamber during (d) divided by the absolute critical temperature of the dense processing fluid.  
     
     
         4 . The method of  claim 1  wherein the dense fluid comprises one or more components selected from the group consisting of carbon dioxide, nitrogen, methane, oxygen, ozone, argon, hydrogen, helium, ammonia, nitrous oxide, hydrogen fluoride, hydrogen chloride, sulfur trioxide, sulfur hexafluoride, nitrogen trifluoride, monofluoromethane, difluoromethane, trifluoromethane, trifluoroethane, tetrafluoroethane, pentafluoroethane, perfluoropropane, pentafluoropropane, hexafluoroethane, hexafluoropropylene, hexafluorobutadiene, and octafluorocyclobutane and tetrafluorochloroethane.  
     
     
         5 . The method of  claim 1  wherein the dense fluid comprises one or more hydrocarbons having 2 to 6 carbon atoms.  
     
     
         6 . The method of  claim 1  wherein the total concentration of the one or more processing agents in the dense processing fluid is between about 0.1 and 20 wt %.  
     
     
         7 . The method of  claim 1  wherein the dense processing fluid comprises one or more processing agents selected from the group consisting of ethyl acetate, ethyl lactate, propyl acetate, butyl acetate, diethyl ether, dipropyl ether, methanol, ethanol, isopropanol, acetonitrile, propionitrile, benzonitrile, ethylene cyanohydrin, ethylene glycol, propylene glycol, ethylene glycol monoacetate, propylene glycol monoacetate, acetone, butanone, acetophenone, trifluoroacetophenone, triethyl amine, tripropyl amine, tributyl amine, 2,4, dimethyl pyridine, dimethylethanolamine, diethylethanolamine, diethylmethanolamine, dimethylmethanolamine, dimethylformamide, dimethylacetamide, ethylene carbonate, propylene carbonate, acetic acid, lactic acid, butane-diol, propane-diol, n-hexane, n-butane, hydrogen peroxide, t-butyl hydroperoxide, ethylenediaminetetraacetic acid, catechol, choline, and trifluoroacetic anhydride.  
     
     
         8 . The method of  claim 1  wherein the dense processing fluid comprises one or more processing agents selected from the group consisting of hydrogen fluoride, hydrogen chloride, chlorine trifluoride, nitrogen trifluoride, monofluoromethane, difluoromethane, trifluoromethane, trifluoroethane, tetrafluoroethane, pentafluoroethane, perfluoropropane, pentafluoropropane, hexafluoroethane, hexafluoropropylene, hexafluorobutadiene, octafluorocyclobutane tetrafluorochloroethane, fluoroxytrifluoromethane (CF 4 O), bis(difluoroxy)methane (CF 4 O 2 ), cyanuric fluoride (C 3 F 3 N 3 ), oxalyl fluoride (C 2 F 2 O 2 ), nitrosyl fluoride (FNO), carbonyl fluoride (CF 2 O), and perfluoromethylamine (CF 5 N).  
     
     
         9 . The method of  claim 1  wherein the dense processing fluid comprises one or more processing agents selected from the group consisting of organometallic precursors, photoresists, photoresist developers, interlayer dielectric materials, silane reagents, and stain-resistant coatings.  
     
     
         10 . The method of  claim 1  which further comprises reducing the pressure of the spent dense processing fluid to yield at least a fluid phase and a residual compound phase, and separating the phases to yield a purified fluid and recovered residual compounds.  
     
     
         11 . The method of  claim 10  which further comprises recycling the purified fluid to provide a portion of the subcritical fluid in (b1).  
     
     
         12 . The method of  claim 10  which further comprises reducing the pressure of the purified fluid to yield a further-purified fluid phase and an additional residual compound phase, and separating the phases to yield a further-purified fluid and additional recovered residual compounds.  
     
     
         13 . The method of  claim 12  which further comprises recycling the further-purified fluid to provide a portion of the subcritical fluid in (b1).  
     
     
         14 . The method of  claim 1  wherein the subcritical fluid in the pressurization vessel prior to heating in (b2) comprises a vapor phase, a liquid phase, or coexisting vapor and liquid phases.  
     
     
         15 . A method for processing an article comprising: 
 (a) introducing the article into a sealable processing chamber and sealing the processing chamber;    (b) preparing a dense processing fluid by: 
 (b1) introducing a subcritical fluid into a pressurization vessel and isolating the vessel;  
 (b2) heating the subcritical fluid at essentially constant volume and essentially constant density to yield a dense fluid; and  
 (b3) introducing one or more processing agents into the pressurization vessel 
 before introducing the subcritical fluid into the pressurization vessel, or  
 after introducing the subcritical fluid into the pressurization vessel but before heating the pressurization vessel, or  
 after introducing the subcritical fluid into the pressurization vessel and after heating the pressurization vessel;  
 
   (c) transferring at least a portion of the dense processing fluid from the pressurization vessel to the processing chamber, wherein the transfer of the dense processing fluid is driven by the difference between the pressure in the pressurization vessel and the pressure in the processing chamber, thereby pressurizing the processing chamber with transferred dense processing fluid;    (d) introducing ultrasonic energy into the processing chamber and contacting the article with the transferred dense processing fluid to yield a spent dense processing fluid and a treated article; and    (e) separating the spent dense processing fluid from the treated article.    
     
     
         16 . An apparatus for processing an article which comprises: 
 (a) a fluid storage tank containing a subcritical fluid;    (b) one or more pressurization vessels and piping means for transferring the subcritical fluid from the fluid storage tank to one or more pressurization vessels;    (c) heating means to heat the contents of each of the one or more pressurization vessels at essentially constant volume and essentially constant density to convert the subcritical fluid into a dense fluid;    (d) a sealable processing chamber for contacting an article with the dense fluid;    (e) ultrasonic generation means for introducing ultrasonic energy into the sealable processing chamber;    (f) piping means for transferring the dense fluid from the one or more pressurization vessels into the sealable processing chamber; and    (g) one or more processing agent storage vessels and pumping means to inject one or more processing agents (1) into the one or more pressurization vessels or (2) into the piping means for transferring the dense fluid from the one or more pressurization vessels to the sealable processing chamber or (3) into the sealable processing chamber.    
     
     
         17 . The apparatus of  claim 16  which further comprises pressure reduction means and phase separation means to separate a spent dense processing fluid withdrawn from the processing chamber to yield at least a purified fluid and one or more recovered residual compounds.  
     
     
         18 . The apparatus of  claim 17  which further comprises recycle means to recycle the purified fluid to the fluid storage tank.  
     
     
         19 . A method for processing an article comprising: 
 (a) introducing the article into a sealable processing chamber and sealing the processing chamber;    (b) providing a dense processing fluid in the processing chamber;    (c) introducing ultrasonic energy into the processing chamber and varying the frequency of the ultrasonic energy while contacting the article with the dense processing fluid to yield a spent dense processing fluid and a treated article; and    (e) separating the spent dense processing fluid from the treated article.    
     
     
         20 . The method of  claim 19  wherein the frequency of the ultrasonic energy is increased during (c).  
     
     
         21 . The method of  claim 19  wherein the frequency of the ultrasonic energy is decreased during (c).  
     
     
         22 . The method of  claim 19  wherein the dense processing fluid is prepared by: 
 (a) introducing a subcritical fluid into a pressurization vessel and isolating the vessel;  
 (b) heating the subcritical fluid at essentially constant volume and essentially constant density to yield a dense fluid; and  
 (c) providing the dense processing fluid by one or more steps selected from the group consisting of 
 (1) introducing one or more processing agents into the dense fluid while transferring the dense fluid from the pressurization vessel to the processing chamber,  
 (2) introducing one or more processing agents into the pressurization vessel to form a dense processing fluid and transferring the dense processing fluid from the pressurization vessel to the processing chamber,  
 (3) introducing one or more processing agents into the derise fluid in the processing chamber after transferring the dense fluid from the pressurization vessel to the processing chamber,  
 (4) introducing one or more processing agents into the pressurization vessel before introducing the subcritical fluid into the pressurization vessel,  
 (5) introducing one or more processing agents into the pressurization vessel after introducing the subcritical fluid into the pressurization vessel but before heating the pressurization vessel, and  
 (6) introducing one or more processing agents into the pressurization vessel after introducing the subcritical fluid into the pressurization vessel and after heating the pressurization vessel.  
 
 
     
     
         23 . The method of  claim 19  wherein the dense processing fluid is prepared by: 
 (a) introducing a subcritical fluid into the sealable processing chamber and isolating the chamber;  
 (b) heating the subcritical fluid at essentially constant volume and essentially constant density to yield a dense fluid; and  
 (c) providing the dense processing fluid by one or more steps selected from the group consisting of 
 (1) introducing one or more processing agents into the sealable processing chamber before introducing the subcritical fluid into the sealable processing chamber,  
 (2) introducing one or more processing agents into the sealable processing chamber after introducing the subcritical fluid into the sealable processing chamber but before heating the subcritical fluid therein, and  
 (3) introducing one or more processing agents into the sealable processing chamber after introducing the subcritical fluid into the sealable processing chamber and after heating the subcritical fluid therein.  
 
 
     
     
         24 . A method for processing an article comprising: 
 (a) introducing the article into a sealable processing chamber and sealing the processing chamber;    (b) providing a dense fluid in the processing chamber;    (c) introducing ultrasonic energy into the processing chamber and varying the frequency of the ultrasonic energy while contacting the article with the dense fluid to yield a spent dense fluid and a treated article; and    (e) separating the spent dense fluid from the treated article.    
     
     
         25 . A method for processing an article comprising: 
 (a) introducing the article into a sealable processing chamber and sealing the processing chamber;    (b) providing a dense processing fluid in the processing chamber;    (c) introducing ultrasonic energy into the processing chamber intermittently while contacting the article with the dense processing fluid to yield a spent dense processing fluid and a treated article; and    (e) separating the spent dense processing fluid from the treated article.    
     
     
         26 . A method for processing an article comprising: 
 (a) introducing the article into a sealable processing chamber and sealing the processing chamber;    (b) providing a dense fluid in the processing chamber;    (c) introducing ultrasonic energy into the processing chamber intermittently while contacting the article with the dense fluid to yield a spent dense fluid and a treated article; and    (e) separating the spent dense fluid from the treated article.