Substrate cleaning method and substrate cleaning apparatus

Abstract

In a cleaning treatment of a substrate using an aqueous solution of ammonium fluoride or a mixture of an aqueous solution of ammonium fluoride and hydrofluoric acid as a cleaning liquid, the cleaning liquid is replenished by at least one liquid selected from the group consisting of water, ammonia, aqueous ammonia, and an aqueous solution of ammonium fluoride with the lapse of time during the use of the cleaning liquid, in which the required amount of the liquid to be added according to the time lapse is calculated based on the measurement date and controlled, or the component concentration of the cleaning liquid is detected and the liquid is added according to the obtained result, so that not only can the substrate be cleaned uniformly and stably, but also a resource saving and a reduction in waste can be achieved.

What is claimed is:  
     
         1 . A substrate cleaning method for cleaning a substrate using a cleaning liquid comprising at least one selected from the group consisting of an aqueous solution of ammonium fluoride, and a mixture of an aqueous solution of ammonium fluoride and hydrofluoric acid, comprising the steps of: 
 dipping and cleaning the substrate in said cleaning liquid; and    adding a replenishing liquid comprising at least one selected from the group consisting of water, ammonia, aqueous ammonia, and an aqueous solution of ammonium fluoride with lapse of time during said cleaning liquid is used.    
     
     
         2 . The substrate cleaning method according to  claim 1 , further comprising the step of measuring characteristics of said cleaning liquid, wherein a kind and an amount of said replenishing liquid are determined in response to a result of the measurement of said cleaning liquid.  
     
     
         3 . The substrate cleaning method according to  claim 2 , wherein, in the measuring step, hydrofluoric acid concentration is measured at a predetermined time interval and water is fed as said replenishing liquid so that a measurement value of said concentration falls within a predetermined range.  
     
     
         4 . The substrate cleaning method according to  claim 2 , wherein said characteristics of said cleaning liquid is measured by at least one measurement selected from the group consisting of measurements of an absorbance at a predetermined wavelength, an infrared absorption spectrum, an ultraviolet absorption spectrum, an index of refraction, a specific gravity, a transmittance, and an electric conductivity, a measurement by means of a moisture titrator, and a measurement by means of liquid (ion) chromatography.  
     
     
         5 . The substrate cleaning method according to  claim 3 , wherein said hydrofluoric acid concentration of said cleaning liquid is measured by at least one measurement selected from the group consisting of measurements of an absorbance at a predetermined wavelength, an infrared absorption spectrum, an ultraviolet absorption spectrum, an index of refraction, a specific gravity, a transmittance, and an electric conductivity, a measurement by means of a moisture titrator, and a measurement by means of liquid (ion) chromatography.  
     
     
         6 . A substrate cleaning apparatus for cleaning a substrate, comprising: 
 a substrate cleaning bath containing therein a substrate cleaning liquid comprising at least one liquid selected from the group consisting of an aqueous solution of ammonium fluoride, and a mixture of an aqueous solution of ammonium fluoride and hydrofluoric acid; and    liquid feeding means for feeding a liquid comprising at least one selected from the group consisting of water, ammonia, aqueous ammonia, and an aqueous solution of ammonium fluoride.    
     
     
         7 . The substrate cleaning apparatus according to  claim 6 , further comprising: 
 measuring means for measuring characteristics of said cleaning liquid in said substrate cleaning bath; and    control means for arithmetically processing a signal from said measuring means to control the feeding of the liquid from said liquid feeding means to substrate cleaning bath.    
     
     
         8 . The substrate cleaning apparatus according to  claim 7 , wherein said measuring means comprises means for measuring at least one wavelength characteristic selected from the group consisting of an absorbance at a predetermined wavelength, an infrared absorption spectrum, an ultraviolet absorption spectrum, and an index of refraction.  
     
     
         9 . The substrate cleaning apparatus according to  claim 7 , wherein said measuring means comprises means for measuring at least one physical value selected from the group consisting of a specific gravity and a transmittance.  
     
     
         10 . The substrate cleaning apparatus according to  claim 7 , wherein said measuring means comprises means for measuring an electric conductivity.  
     
     
         11 . The substrate cleaning apparatus according to  claim 7 , wherein said measuring means comprises at least one measurement means selected from the group consisting of a moisture titrator and liquid (ion) chromatography.  
     
     
         12 . The substrate cleaning apparatus according to  claim 7 , wherein said measuring means measures hydrofluoric acid concentration of said cleaning liquid.  
     
     
         13 . The substrate cleaning apparatus according to  claim 12 , wherein said measuring means comprises means for measuring at least one wavelength characteristic selected from the group consisting of an absorbance at a predetermined wavelength, an infrared absorption spectrum, an ultraviolet absorption spectrum, and an index of refraction.  
     
     
         14 . The substrate cleaning apparatus according to  claim 12 , wherein said measuring means comprises means for measuring at least one physical value selected from the group consisting of a specific gravity and a transmittance.  
     
     
         15 . The substrate cleaning apparatus according to  claim 12 , wherein said measuring means comprises means for measuring an electric conductivity.  
     
     
         16 . The substrate cleaning apparatus according to  claim 12 , wherein said measuring means comprises at least one measurement means selected from the group consisting of a moisture titrator and liquid (ion) chromatography.