Substrate cleaning method and substrate cleaning apparatus

Abstract

A valve is closed while a cleaning liquid is fed into a tubular body of a cleaning nozzle, and a piezoelectric element applies vibrations to the cleaning liquid. This causes droplets of the cleaning liquid to be produced and discharged from a plurality of discharge holes. The droplet diameter of the discharged droplets is in the range from 15 to 200 μm, and the distribution of the droplet diameter is such that the value of where a value of 3σ does not exceed 10% of the average droplet diameter. The droplet speed is in the range from 20 to 100 meters per second, and the distribution of the droplet speed is such that the value of where a value of 3σ does not exceed 10% of the average droplet speed. The droplet flow rate is not less than 10 milliliters per minute. Discharging the droplets of the cleaning liquid from the cleaning nozzle toward a substrate while satisfying these discharge conditions improves cleaning efficiency without damages to the substrate.

1 . A substrate cleaning method for cleaning a substrate by discharging droplets of a cleaning liquid toward the substrate, wherein droplets of a cleaning liquid having an average droplet diameter in the range from 15 to 200 μm and a droplet diameter distribution where a value of 3σ (where σ is a standard deviation) does not exceed 10% of said average droplet diameter are produced and discharged toward a substrate. 
     
     
         2 . The substrate cleaning method according to  claim 1 , wherein
 droplets having an average droplet speed in the range from 20 to 100 meters per second and a droplet speed distribution where a value of 3σ (where σ is a standard deviation) does not exceed 10% of said average droplet speed are discharged toward the substrate.   
     
     
         3 . The substrate cleaning method according to  claim 2 , wherein
 said droplets are discharged toward the substrate at a droplet flow rate of not less than 10 milliliters per minute.   
     
     
         4 . A substrate cleaning method for cleaning a semiconductor substrate by discharging droplets of a cleaning liquid toward the semiconductor substrate, wherein
 droplets of a cleaning liquid having an average droplet diameter in the range from 15 to 30 μm and a droplet diameter distribution where a value of 3σ (where σ is a standard deviation) does not exceed 2 μm are produced and discharged toward a semiconductor substrate.   
     
     
         5 . The substrate cleaning method according to  claim 4 , wherein
 droplets having an average droplet speed in the range from 20 to 60 meters per second and a droplet speed distribution where a value of 3σ (where σ is a standard deviation) does not exceed 5 meters per second are discharged toward the semiconductor substrate.   
     
     
         6 . The substrate cleaning method according to  claim 5 , wherein
 said droplets are discharged toward the semiconductor substrate at a droplet flow rate of not less than 10 milliliters per minute.   
     
     
         7 . A substrate cleaning method for cleaning a substrate by discharging droplets of a cleaning liquid toward the substrate, wherein
 a cleaning liquid is fed to a tubular body including a plurality of discharge holes formed in a wall surface thereof, and vibrations are applied to the cleaning liquid, whereby droplets of the cleaning liquid having an average droplet diameter in the range from 15 to 200 μm and a droplet diameter distribution where a value of 3σ (where σ is a standard deviation) does not exceed 10% of said average droplet diameter are discharged from said plurality of discharge holes toward a substrate.   
     
     
         8 . The substrate cleaning method according to  claim 7 , wherein
 droplets having an average droplet speed in the range from 20 to 100 meters per second and a droplet speed distribution where a value of 3σ (where σ is a standard deviation) does not exceed 10% of said average droplet speed are discharged from said plurality of discharge holes toward the substrate.   
     
     
         9 . The substrate cleaning method according to  claim 8 , wherein
 droplets of the cleaning liquid are discharged from said plurality of discharge holes toward the substrate at a droplet flow rate of not less than 10 milliliters per minute.   
     
     
         10 . A substrate cleaning method for cleaning a semiconductor substrate by discharging droplets of a cleaning liquid toward the semiconductor substrate, wherein
 a cleaning liquid is fed to a tubular body including a plurality of discharge holes formed in a wall surface thereof, and vibrations are applied to the cleaning liquid, whereby droplets of the cleaning liquid having an average droplet diameter in the range from 15 to 30 μm and a droplet diameter distribution where a value of 3σ (where σ is a standard deviation) does not exceed 2 μm are discharged from said plurality of discharge holes toward a semiconductor substrate.   
     
     
         11 . The substrate cleaning method according to  claim 10 , wherein
 droplets having an average droplet speed in the range from 20 to 60 meters per second and a droplet speed distribution where a value of 3σ (where σ is a standard deviation) does not exceed 5 meters per second are discharged from said plurality of discharge holes toward the semiconductor substrate.   
     
     
         12 . The substrate cleaning method according to  claim 11 , wherein
 droplets of the cleaning liquid are discharged from said plurality of discharge holes toward the semiconductor substrate at a droplet flow rate of not less than 10 milliliters per minute.   
     
     
         13 . A substrate cleaning apparatus for cleaning a substrate by discharging droplets of a cleaning liquid toward the substrate, comprising
 a cleaning nozzle having a tubular body including a plurality of discharge holes formed in a wall surface thereof, and a piezoelectric element affixed to said wall surface, said cleaning nozzle being configured to apply vibrations to a cleaning liquid fed to said tubular body from said piezoelectric element, thereby discharging droplets of the cleaning liquid having an average droplet diameter in the range from 15 to 200 μm and a droplet diameter distribution where a value of 3σ (where σ is a standard deviation) does not exceed 10% of said average droplet diameter from said plurality of discharge holes toward a substrate.   
     
     
         14 . The substrate cleaning apparatus according to  claim 13 , wherein
 said cleaning nozzle discharges droplets having an average droplet speed in the range from 20 to 100 meters per second and a droplet speed distribution where a value of 3σ (where σ is a standard deviation) does not exceed 10% of said average droplet speed from said plurality of discharge holes toward the substrate.   
     
     
         15 . The substrate cleaning apparatus according to  claim 14 , wherein
 said cleaning nozzle discharges droplets of the cleaning liquid from said plurality of discharge holes toward the substrate at a droplet flow rate of not less than 10 milliliters per minute.   
     
     
         16 . A substrate cleaning apparatus for cleaning a semiconductor substrate by discharging droplets of a cleaning liquid toward the semiconductor substrate, wherein
 a cleaning nozzle having a tubular body including a plurality of discharge holes formed in a wall surface thereof, and a piezoelectric element affixed to said wall surface, said cleaning nozzle being configured to apply vibrations to a cleaning liquid fed to said tubular body from said piezoelectric element, thereby discharging droplets of the cleaning liquid having an average droplet diameter in the range from 15 to 30 μm and a droplet diameter distribution where a value of 3σ (where σ is a standard deviation) does not exceed 2 μm from said plurality of discharge holes toward a semiconductor substrate.   
     
     
         17 . The substrate cleaning apparatus according to  claim 16 , wherein
 said cleaning nozzle discharges droplets having an average droplet speed in the range from 20 to 60 meters per second and a droplet speed distribution where a value of 3σ (where σ is a standard deviation) does not exceed 5 meters per second from said plurality of discharge holes toward the semiconductor substrate.   
     
     
         18 . The substrate cleaning apparatus according to  claim 17 , wherein
 said cleaning nozzle discharges droplets of the cleaning liquid from said plurality of discharge holes toward the semiconductor substrate at a droplet flow rate of not less than 10 milliliters per minute.   
     
     
         19 . The substrate cleaning apparatus according to  claim 13 , wherein
 said tubular body is cylindrical.   
     
     
         20 . The substrate cleaning apparatus according to  claim 13 , further comprising:
 a pressure pump for feeding a cleaning liquid through an opening at a first end of said tubular body; and   a valve for closing an opening at a second end of said tubular body.