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 apparatus for cleaning a substrate by discharging droplets of a cleaning liquid toward the substrate, comprising:
 a cleaning nozzle having a plurality of discharge holes formed in the wall surface of a tubular body made of quartz including a hollow interior space formed therein, wherein   said cleaning nozzle is configured such that while the cleaning liquid always continues to be fed to said tubular body, the liquid pressure of the cleaning liquid within the tubular body increases when the cleaning process is performed, whereby the cleaning liquid is discharged from each of said plurality of discharge holes, and the cleaning liquid flowing out of each of said plurality of discharge holes is divided by the vibration generated by the alternating voltage having the fixed predetermined frequency, thereby, only 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 are produced and discharged toward a substrate at a predetermined droplet flow rate from each of said plurality of discharge holes during the cleaning process.   
     
     
         2 . The substrate cleaning apparatus according to  claim 1 , wherein
 said cleaning nozzle is configured such that only 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 apparatus according to  claim 1 , wherein said cleaning nozzle is configured such that said droplets are discharged toward the substrate at a droplet flow rate of not less than 10 milliliters per minute. 
     
     
         4 . The substrate cleaning apparatus according to  claim 1 , further comprising:
 a pivoting part for causing said cleaning nozzle to pivot over the rotating substrate and discharging droplets of said cleaning liquid from said cleaning nozzle toward the rotating substrate.   
     
     
         5 . The substrate cleaning apparatus according to  claim 4 , further comprising:
 a drying part for stopping discharge of the droplets from said cleaning nozzle, and thereafter, increasing the number of rotation of the substrate to perform the drying process of the substrate.   
     
     
         6 . A substrate cleaning apparatus for cleaning a semiconductor substrate by discharging droplets of a cleaning liquid toward the semiconductor substrate comprising:
 a cleaning nozzle having a plurality of discharge holes formed in the wall surface of a tubular body made of quartz including a hollow interior space formed therein, wherein   said cleaning nozzle is configured such that while the cleaning liquid always continues to be fed to said tubular body, the liquid pressure of the cleaning liquid within the tubular body increases when the cleaning process is performed, whereby the cleaning liquid is discharged from each of said plurality of discharge holes, and the cleaning liquid flowing out of each of said plurality of discharge holes is divided by the vibration generated by the alternating voltage having the fixed predetermined frequency, thereby, only 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 produced and discharged toward a semiconductor substrate at a predetermined droplet flow rate from each of said plurality of discharge holes during the cleaning process.   
     
     
         7 . The substrate cleaning apparatus according to  claim 6 , wherein
 said cleaning nozzle is configured such that only 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.   
     
     
         8 . The substrate cleaning apparatus according to  claim 6 , wherein
 said cleaning nozzle is configured such that said droplets are discharged toward the semiconductor substrate at a droplet flow rate of not less than 10 milliliters per minute.   
     
     
         9 . The substrate cleaning apparatus according to  claim 6 , further comprising:
 a pivoting part for causing said cleaning nozzle to pivot over the rotating semiconductor substrate and discharging droplets of said cleaning liquid from said cleaning nozzle toward the rotating semiconductor substrate.   
     
     
         10 . The substrate cleaning apparatus according to  claim 9 , further comprising:
 a drying part for stopping discharge of the droplets from said cleaning nozzle, and thereafter, increasing the number of rotation of the semiconductor substrate to perform the drying process of the semiconductor substrate.