Electroless plating method

Abstract

An electroless plating method which can prevent stoppage of a plating reaction and a decrease in a plating rate is disclosed. This method includes: circulating a plating solution through a plating bath while heating the plating solution; immersing the substrate in the plating solution in the plating bath; forming a first electroless plating film on the substrate while circulating the plating solution at a first flow rate during a period from when the substrate is immersed in the plating solution until a predetermined time elapses; and forming a second electroless plating film on the first electroless plating film while circulating the plating solution at a second flow rate that is lower than the first flow rate after the predetermined time has elapsed.

What is claimed is: 
     
         1 . An electroless plating method for plating a substrate, comprising:
 circulating a plating solution through a plating bath while heating the plating solution;   immersing the substrate in the plating solution in the plating bath;   forming a first electroless plating film on the substrate while circulating the plating solution at a first flow rate during a period from when the substrate is immersed in the plating solution until a predetermined time elapses; and   forming a second electroless plating film on the first electroless plating film while circulating the plating solution at a second flow rate that is lower than the first flow rate after the predetermined time has elapsed.   
     
     
         2 . The electroless plating method according to  claim 1 , wherein:
 the substrate has an underlying metal and a dielectric film that covers the underlying metal;   the dielectric film has an opening through which the underlying metal is exposed; and   the first electroless plating film is formed on an exposed surface of the underlying metal.   
     
     
         3 . The electroless plating method according to  claim 2 , wherein the first electroless plating film is formed in the opening of the dielectric fihn. 
     
     
         4 . The electroless plating method according to  claim 1 , wherein the predetermined time is in a range of 30 seconds to 10 minutes. 
     
     
         5 . The electroless plating method according to  claim 1 , wherein the predetermined time is not more than one-tenth of a time for forming the second electroless plating film while circulating the plating solution at the second flow rate. 
     
     
         6 . The electroless plating method according to  claim 1 , wherein a flow velocity of the plating solution moving on the substrate when the plating solution is circulating at the first flow rate is in a range of 50 cm/sec to 500 cm/sec, and a flow velocity of the plating solution moving on the substrate when the plating solution is circulating at the second flow rate is in a range of 0.05 cm/sec to 200 cm/sec. 
     
     
         7 . The electroless plating method according to  claim 1 , wherein a flow velocity of the plating solution moving on the substrate when the plating solution is circulating at the first flow rate is at least three times a flow velocity of the plating solution moving on the substrate when the plating solution is circulating at the second flow rate. 
     
     
         8 . The electroless plating method according to  claim 1 , further comprising:
 cleaning, the substrate by immersing the substrate in a cleaning liquid while maintaining the cleaning liquid within a predetermined temperature range,   wherein immersing the substrate in the plating solution in the plating bath comprises immersing the cleaned substrate in the plating solution in the plating bath, and   the predetermined temperature range is from 30° C. to a temperature higher by 10° C. than a temperature of the plating solution.   
     
     
         9 . The electroless plating method according to  claim 8 , further comprising:
 deaerating the cleaning liquid.   
     
     
         10 . The electroless plating method according to  claim 8 , further comprising:
 supplying an inert gas into the cleaning liquid.   
     
     
         11 . An electroless plating method for plating a substrate, comprising:
 supplying a heated plating solution to the substrate at a first flow rate to form a first electroless plating film on the substrate; and   after a predetermined time has elapsed since supply of the plating solution is started, supplying the heated plating solution to the substrate at a second flow rate that is lower than the first flow rate to form a second electroless plating film on the first electroless plating film.