Substrate processing apparatus and method

Abstract

A method and apparatus for removing materials from a substrate contained in a closed, pressurized processing vessel. An exemplary method includes the steps of inserting a substrate to be processed into the processing vessel, closing the processing vessel gas-tight, and then pressurizing the processing vessel. A pressurized processing solution is introduced to the processing vessel while the processing vessel is maintained under pressure. The substrate is exposed to the processing solution, so that a processing step ensues and the desired material is removed from the substrate by reaction with the pressurized processing fluid. The processing is performed at greater than atmospheric pressure to maintain a high concentration of active components of the processing solution by increasing the solubility of active solution components, and to inhibit evaporation of volatile components of the processing solution.

What is claimed is:  
     
         1 . A method of removing a material from a surface of a substrate, said method comprising the steps of: 
 inserting the substrate including the material into an open processing vessel;    closing the processing vessel gas-tight;    pressurizing the processing vessel to greater than atmospheric pressure;    introducing a pressurized processing solution into the pressurized processing vessel so that a surface of the substrate is exposed to the pressurized processing solution; and    processing the substrate to remove the material from the surface of the substrate by allowing the pressurized processing fluid to react with the material, wherein said processing solution is maintained at higher than atmospheric pressure during introduction into the processing vessel and during at least part of processing of the substrate.    
     
     
         2 . The method of  claim 1  wherein the material comprises an organic material.  
     
     
         3 . The method of  claim 2  wherein the organic material comprises a photoresist.  
     
     
         4 . The method of  claim 1  wherein the processing solution comprises an oxidant.  
     
     
         5 . The method of  claim 4  wherein the oxidant is selected from the group consisting of ozone, oxygen, hydrogen peroxide, and mixtures of ozone and hydrogen peroxide.  
     
     
         6 . The method of  claim 4  wherein the oxidant is at least one of an oxygen radical and a hydroxy radical generated from exposure to UV radiation or an electrical discharge.  
     
     
         7 . The method of  claim 4  wherein the oxidant comprises ozone absorbed in deionized water.  
     
     
         8 . The method of  claim 4  wherein the oxidant comprises ozone absorbed in a solution selected from the group consisting of an acidic solution, a basic solution, and an organic solvent.  
     
     
         9 . The method of  claim 4  wherein the oxidant is ozone at a concentration greater than about 0.1 ppm in a temperature range of between about −95° C. and 200° C.  
     
     
         10 . The method of  claim 4  wherein the oxidant is ozone at a concentration greater than about 0.1 and 5000 ppm in a temperature range of between about −95° C. and 200° C.  
     
     
         11 . The method of  claim 1  wherein the processing solution comprises an acid.  
     
     
         12 . The method of  claim 11  wherein the acid comprises an organic acid  
     
     
         13 . The method of  claim 12  wherein the organic acid is selected from the group consisting of acetic acid, formic acid, butyric acid, propionic acid, citric acid, oxalic acid, and sulfonic acid.  
     
     
         14 . The method of  claim 1  wherein the material comprises an inorganic material.  
     
     
         15 . The method of  claim 14  wherein the inorganic material is selected from the group consisting of silicon, polysilicon, silicon oxide, silicon nitride, TiN, GaAs, GaN, InP, GaInP, SiGe, Al, Cu, AlCuSi, W, silver, gold, molybdenum, titanium, titanium-tungsten, silicon carbide, alumina, and other metals.  
     
     
         16 . The method of  claim 1  wherein the pressurized processing solution comprises an acid selected from the group consisting of hydrofluoric acid, hydrochloric acid, sulfuric acid, Caro's acid, phosphoric acid, nitric acid, chromic acid, aqua regia, sulfuric/ammonium persulfate, buffered oxide etch, and carbonic acid.  
     
     
         17 . The method of  claim 16  wherein the pressurized processing solution further comprises ozone.  
     
     
         18 . The method of  claim 1  wherein the processing solution comprises a base.  
     
     
         19 . The method of  claim 18  wherein the base is selected from the group consisting of ammonium hydroxide, tetramethyl ammonium hydroxide, sodium hydroxide, potassium hydroxide, n-methylpyrrolidone, and monomethanol amine (MEA).  
     
     
         20 . The method of  claim 1  wherein the processing solution is pressurized to about 50 ATM or less  
     
     
         21 . The method of  claim 1  wherein the processing solution is pressurized to about 10 ATM or less.  
     
     
         22 . The method of  claim 1  wherein the processing solution is pressurized to between about 50 and 100 ATM.  
     
     
         23 . The method of  claim 1 , further comprising a step of: 
 maintaining the processing solution above room temperature during the step of processing.    
     
     
         24 . The method of  claim 1 , further comprising a step of: 
 maintaining the processing solution above a freezing temperature of the processing solution during the step of processing.    
     
     
         25 . The method of  claim 1 , further comprising a step of: 
 after the step of processing, transferring the processing solution to a holding tank, while maintaining the processing solution under pressure.    
     
     
         26 . The method of  claim 1 , further comprising: 
 removing the pressurized processing solution from the processing vessel after completion of processing;    introducing a second pressurized processing solution into the pressurized processing vessel to contact the substrate; and    processing the substrate to remove additional material from the surface of the substrate by allowing the second pressurized processing fluid to react with the additional material,    wherein said second processing solution is maintained at a pressure higher than atmospheric pressure prior to introduction into the processing vessel during introduction into the processing vessel and during at least part of processing of the substrate.    
     
     
         27 . The method of  claim 1 , further comprising applying sonic energy to the pressurized processing vessel during the processing step.  
     
     
         28 . The method of  claim 1 , further comprising: 
 evacuating the sealed processing vessel after the closing step; and    pressurizing the evacuated processing chamber by the introduction of a flow of gas prior to introduction of the pressurized processing solution.    
     
     
         29 . The method of  claim 28 , wherein the evacuated processing chamber is pressurized by a flow of an inert gas.  
     
     
         30 . The method of  claim 28 , wherein the evacuated processing chamber is pressurized by a flow of a gas that will react with the material.  
     
     
         31 . The method of  claim 1 , further comprising: 
 pressurizing the processing solution to above atmospheric pressure prior to introduction into the processing vessel.    
     
     
         32 . The method of  claim 1 , wherein the step of processing further comprises inducing turbulence in the pressurized flow of processing solution.  
     
     
         33 . The method of  claim 1 , wherein the step of processing further comprises maintaining a laminar or a plug flow in the pressurized processing solution.  
     
     
         34 . The method of  claim 1 , further comprising the step of rotating the substrate during the processing step to reduce a thickness of a liquid layer present over the substrate surface.  
     
     
         35 . The method of  claim 1 , wherein a pressure of the processing vessel is changed during the processing step.  
     
     
         36 . The method of  claim 1 , wherein the pressurized processing solution experiences a pressure drop upon introduction to the pressurized processing vessel, such that outgassing of a solution component occurs.  
     
     
         37 . The method of  claim 1 , wherein the substrate is submerged in the processing solution.  
     
     
         38 . The method of  claim 1 , wherein the processing solution is introduced into the processing vessel as a spray of droplets to wet a surface of the substrate.  
     
     
         39 . The method of  claim 1 , wherein the surface of the substrate is suspended over the processing solution and thereby exposed to vapors from the processing solution.  
     
     
         40 . The method of  claim 1 , wherein the substrate is rotated during at least part of the processing step.  
     
     
         41 . The method of  claim 1  wherein: 
 the step of closing the processing vessel comprises sealing a separate enclosure gas-tight around the processing vessel; and  
 the step of pressurizing the processing vessel comprises pressurizing the separate enclosure.  
 
     
     
         42 . The method of  claim 1  wherein the processing step comprises enhancing bubble formation in the processing solution.  
     
     
         43 . The method of  claim 1  wherein the processing step comprises suppressing bubble formation in the processing solution.  
     
     
         44 . The method of  claim 1  further comprising the step of drying the substrate after the processing step by generating a surface tension gradient between a meniscus of the processing solution on the substrate surface and a remaining bulk portion of the processing solution as the substrate is moved relative to the pressurized processing solution.  
     
     
         45 . The method of  claim 44  wherein the pressure induces a surface tension lowering component to be concentrated in the meniscus to generate the surface tension gradient.  
     
     
         46 . The method of  claim 1  wherein the processing solution further comprises a component selected from the group consisting of a reducing agent, a wetting agent, a surfactant, and a surface modifying reactant.  
     
     
         47 . A method of drying a substrate comprising: 
 positioning a substrate within a gas-tight processing vessel;    pressurizing the processing vessel to greater than atmospheric pressure;    introducing a pressurized rinsing liquid into the processing vessel to submerge the substrate, the rinsing liquid comprising a surface-tension lowering component concentrated at a surface of the rinsing solution; and    moving the processed substrate relative to the rinsing liquid such that a surface tension gradient is created between a meniscus on the substrate surface and a remaining bulk portion of the rinsing liquid, the surface tension gradient drawing liquid from the substrate surface into the remaining bulk rinsing liquid.    
     
     
         48 . The method of  claim 47  wherein the surface tension lowering component is concentrated in the meniscus from a pressurized gas present in the gas tight processing vessel.  
     
     
         49 . An apparatus for removing a material from a surface of a substrate, comprising: 
 a processing vessel configured to receive and contain a substrate in a gas-tight sealed environment;    a pressurized processing solution source in fluid communication with the processing vessel through an inlet valve, the pressurized processing solution source configured to containing a pressurized processing solution having a concentration of a component greater than available in the solution at atmospheric pressure; and    a drain valve enabling fluid communication of the processing vessel with a drain.    
     
     
         50 . The apparatus of  claim 49  further comprising: 
 a pressurized holding vessel configured to maintain a pressurized processing solution under pressure when not being used in the processing vessel; and  
 a control valve coupled between the processing vessel and the holding vessel for controlling flow of the processing solution from the holding vessel and to the processing vessel.  
 
     
     
         51 . The apparatus of  claim 49  further comprising a megasonic unit in acoustic communication with the processing vessel and configured to apply sonic energy to the processing vessel.  
     
     
         52 . The apparatus of  claim 49  further comprising a temperature control unit in thermal communication with the processing vessel and configured to apply or remove thermal energy from the processing vessel.  
     
     
         53 . The apparatus of  claim 49  further comprising a circulating loop including a pump configured to transfer the pressurized processing solution out of the processing vessel through a circulating outlet port and into the pressurized vessel through a circulating inlet port.  
     
     
         54 . The apparatus of  claim 49  further comprising a stirrer within the vessel to circulate fluid within the vessel.  
     
     
         55 . The apparatus of  claim 49  further comprising a vacuum pump in communication with the processing vessel through a vacuum valve.  
     
     
         56 . The apparatus of  claim 49  further comprising an ozonating apparatus in fluid communication with the pressurized processing vessel and configured to cause ozone to be dissolved in the pressurized processing solution.  
     
     
         57 . The apparatus of  claim 56  wherein the ozonating apparatus comprises: 
 an oxygen source;  
 an ozone generator in fluid communication with the oxygen source; and  
 an injector structure in fluid communication with the ozone generator, the injector structure configured to receive a flow of an ozone-containing gas from an outlet of the ozone generator and to cause ozone from the ozone-containing gas to be dissolved within a flow of the pressurized processing fluid.  
 
     
     
         58 . The apparatus of  claim 57  further comprising: 
 a surge vessel in selective fluid communication with the processing vessel through a surge valve; and  
 an ozonation loop in fluid communication with the surge vessel and with the injector structure.  
 
     
     
         59 . The apparatus of  claim 57  wherein the injector structure comprises a venturi injector.  
     
     
         60 . The apparatus of  claim 57  wherein the injector structure comprises a membrane gasifier.  
     
     
         61 . The apparatus of  claim 57  further comprising a static mixer to promote interaction between the ozone and the processing solution.  
     
     
         62 . The apparatus of  claim 57  further comprising a contact column to lengthen a contact time between the ozone and the processing solution.  
     
     
         63 . The apparatus of  claim 57  further comprising a degasser to remove bubbles from the processing solution.  
     
     
         64 . The apparatus of  claim 49  further comprising a nozzle configured to direct a pressurized flow of a processing solution into contact with a substrate present within the processing vessel.  
     
     
         65 . The apparatus of  claim 64  wherein the processing vessel is configured to submerge the substrate within the processing solution and the nozzle is immersed within the processing solution.  
     
     
         66 . The apparatus of  claim 64  wherein the nozzle is configured to spray droplets of processing solution onto the substrate.  
     
     
         67 . The apparatus of  claim 49  wherein the vessel is configured to support the substrate within a vapor phase produced from the processing liquid.