Agitation of electrolytic solution in electrodeposition

Abstract

In a reverse pulse plating of a substrate ( 110 ), the electrolytic solution is agitated with a greater power on forward pulses ( 210 ) than on reverse pulses ( 220 ). An ultrasound agitation source ( 170 ) can be positioned at the bottom of the substrate ( 110 ) if the anode ( 134 ) is at the top. The ultrasound source may contact the substrate's bottom. Other features are also provided.

1 . An electrodeposition method comprising:
 (1) immersing a substrate into an electrolytic solution;   (2) providing a voltage between at least a portion of the substrate and an electrode spaced from the substrate to effect the electrodeposition onto the substrate, wherein providing the voltage comprises:
 (2A) providing one or more voltage pulses of a first polarity in each of a plurality of first periods of time to provide a net electrodeposition of metal onto the substrate in each first period of time; and 
 (2B) providing one or more voltage pulses of a second polarity in each of a plurality of second periods of time alternating with the first periods of time to provide a net deplating of the metal off the substrate in each second period of time; 
   (3) during a first time interval comprising a plurality of the first periods of time and a plurality of the second periods of time, operating one or more agitation sources to agitate said solution, wherein at least one of the one or more agitation sources is operated in a first mode during each first period of time and in a second mode during each second period of time.   
     
     
         2 . The method of  claim 1  wherein in operation (3), the at least one of the agitation sources provides agitation power for the solution in each first period of time but not in the second periods of time. 
     
     
         3 . The method of  claim 2  wherein in each first period of time in the first time interval, the one or more voltage pulses of the first polarity are provided only while the at least one of the agitation sources agitates said solution. 
     
     
         4 . The method of  claim 2  wherein in each first period of time in the first time interval, the at least one of the agitation sources starts agitating said solution before a start of the one or more voltage pulses of the first polarity. 
     
     
         5 . The method of  claim 4  wherein in each first period of time in the first time interval, the one or more voltage pulses of the first polarity are started only when the solution agitation at the substrate has reached its maximum in the first period of time. 
     
     
         6 . The method of  claim 2  wherein in each first period of time in the first time interval, the one or more voltage pulses of the first polarity stop no later than the at least one of the agitation sources stops providing agitation power to said solution. 
     
     
         7 . The method of  claim 2  wherein in each first period of time in the first time interval, the solution agitation at the substrate becomes zero by the end of the first period of time. 
     
     
         8 . The method of  claim 1  wherein in operation (3), the at least one of the agitation sources provides agitation power for the solution both in each first period of time and in at least one of the second periods of time, but a maximum of the agitation power in each first period of time is greater than in any of the second periods of time. 
     
     
         9 . The method of  claim 1  wherein the at least one of the agitation sources is an ultrasound source. 
     
     
         10 . The method of  claim 9  wherein at least some of ultrasound provided by the ultrasound source is coupled from the ultrasound source directly into the substrate, propagating through the substrate to reach the solution. 
     
     
         11 . The method of  claim 1  wherein the substrate comprises a via, and the electrodeposition comprises electrodeposition into the via. 
     
     
         12 . The method of  claim 11  wherein at a start of the electrodeposition, the via has an aspect ratio of at least 1:1. 
     
     
         13 . An electrodeposition method comprising:
 (1) immersing a substrate into an electrolytic solution;   (2) providing a voltage between at least a portion of the substrate and an electrode spaced from the substrate to effect the electrodeposition onto the substrate, wherein providing the voltage comprises:
 (2A) providing one or more voltage pulses of a first polarity but no pulses of a second polarity opposite to the first polarity in each of a plurality of first periods of time; and 
 (2B) providing one or more voltage pulses of the second polarity but no pulses of the first polarity in each of a plurality of second periods of time alternating with the first periods of time; 
   (3) during a first time interval comprising a plurality of the first periods of time and a plurality of the second periods of time, providing a greater maximum agitation power for the solution in each first period of time than in any of the second periods of time.   
     
     
         14 . The method of  claim 13  wherein in operation (3), the agitation power is zero in each second period of time. 
     
     
         15 . The method of  claim 14  wherein in each first period of time in the first time interval, the one or more voltage pulses of the first polarity are started only while the agitation power is positive. 
     
     
         16 . The method of  claim 14  wherein in each first period of time in the first time interval, the agitation power becomes positive before a start of the one or more voltage pulses of the first polarity. 
     
     
         17 . The method of  claim 16  wherein in each first period of time in the first time interval, the one or more voltage pulses of the first polarity are provided only when the solution agitation at the substrate has reached its maximum in the first period of time. 
     
     
         18 . The method of  claim 14  wherein in each first period of time in the first time interval, the one or more voltage pulses of the first polarity stop while the agitation power is at its maximum for the first period of time. 
     
     
         19 . The method of  claim 14  wherein the solution agitation at the substrate is zero throughout each second period of time in the first time interval. 
     
     
         20 . The method of  claim 13  wherein the agitation power is ultrasonic. 
     
     
         21 . The method of  claim 20  wherein at least some of the agitation power is coupled directly into the substrate, propagating through the substrate to reach the solution. 
     
     
         22 . The method of  claim 13  wherein the substrate comprises a via, and the electrodeposition comprises electrodeposition into the via. 
     
     
         23 . The method of  claim 22  wherein at a start of the electrodeposition, the via has an aspect ratio of at least 1:1. 
     
     
         24 . An electrodeposition method comprising:
 (1) immersing a substrate into an electrolytic solution;   (2) providing a voltage between at least a portion of the substrate and a first electrode spaced from the substrate to effect the electrodeposition onto the substrate, the first electrode being positioned at a first side of the substrate;   (3) during at least a part of operation (2), operating an ultrasound source to emit ultrasound at a second side of the substrate opposite to the first side of the substrate.   
     
     
         25 . The method of  claim 22  wherein the substrate comprises a via in a first side of the substrate, the via is not a through via, and the electrodeposition comprises electrodeposition into the via. 
     
     
         26 . The method of  claim 25  wherein a deepest point of the via is closer to the second side of the substrate than to the via's opening at the first side of the substrate. 
     
     
         27 . The method of  claim 24  wherein at least some of the ultrasound enters the substrate before entering the solution, and reaches the solution through the substrate. 
     
     
         28 . A controller for controlling electrodeposition, the controller comprising circuitry and/or comprising a computer readable medium with computer instructions and/or data, the circuitry and/or the computer instructions and/or data being for:
 (i) providing a voltage between a terminal to be connected to a substrate immersed into an electrolytic solution and an electrode to be spaced from the substrate to effect the electrodeposition onto the substrate, wherein providing the voltage comprises:
 (A) providing one or more voltage pulses of a first polarity in each of a plurality of first periods of time to provide a net electrodeposition of metal onto the substrate in each first period of time; and 
 (B) providing one or more voltage pulses of a second polarity in each of a plurality of second periods of time alternating with the first periods of time to provide a net deplating of the metal off the substrate in each second period of time; 
   (ii) during a first time interval comprising a plurality of the first periods of time and a plurality of the second periods of time, operating one or more agitation sources to agitate said solution, wherein at least one of the one or more agitation sources is operated in a first mode during each first period of time and in a second mode during each second period of time.   
     
     
         29 . The controller of  claim 28  wherein in operation (ii), the at least one of the agitation sources provides agitation power for the solution in each first period of time but not in the second periods of time. 
     
     
         30 . The controller of  claim 29  wherein in each first period of time in the first time interval, the one or more voltage pulses of the first polarity are started only while the at least one of the agitation sources agitates said solution. 
     
     
         31 . The controller of  claim 29  wherein in each first period of time in the first time interval, the at least one of the agitation sources starts agitating said solution before a start of the one or more voltage pulses of the first polarity. 
     
     
         32 . The controller of  claim 29  wherein in each first period of time in the first time interval, the one or more voltage pulses of the first polarity stop no later than the at least one of the agitation sources stops providing agitation power to said solution. 
     
     
         33 . The controller of  claim 28  wherein in operation (ii), the at least one of the agitation sources provides agitation power for the solution both in each first period of time and in at least one of the second periods of time, but a maximum of the agitation power in each first period of time is greater than in any of the second periods of time. 
     
     
         34 . The controller of  claim 28  wherein the at least one of the agitation sources is an ultrasound source. 
     
     
         35 . A controller for controlling electrodeposition, the controller comprising circuitry and/or comprising a computer readable medium with computer instructions and/or data, the circuitry and/or the computer instructions and/or data being for:
 (i) providing a voltage between a terminal to be connected to a substrate immersed into an electrolytic solution and an electrode to be spaced from the substrate to effect the electrodeposition onto the substrate, wherein providing the voltage comprises:
 (A) providing one or more voltage pulses of a first polarity but no pulses of a second polarity opposite to the first polarity in each of a plurality of first periods of time; and 
 (B) providing one or more voltage pulses of the second polarity but no pulses of the first polarity in each of a plurality of second periods of time alternating with the first periods of time; 
   (ii) during a first time interval comprising a plurality of the first periods of time and a plurality of the second periods of time, providing a greater maximum agitation power for the solution in each first period of time than in any of the second periods of time.   
     
     
         36 . The controller of  claim 35  wherein in operation (3), the agitation power is zero in each second period of time. 
     
     
         37 . The controller of  claim 36  wherein in each first period of time in the first time interval, the one or more voltage pulses of the first polarity are provided only while the agitation power is positive. 
     
     
         38 . The controller of  claim 36  wherein in each first period of time in the first time interval, the agitation power becomes positive before a start of the one or more voltage pulses of the first polarity. 
     
     
         39 . The controller of  claim 36  wherein in each first period of time in the first time interval, the one or more voltage pulses of the first polarity stop while the agitation power is at its maximum for the first period of time. 
     
     
         40 . The controller of  claim 35  wherein the agitation power is ultrasonic. 
     
     
         41 . An apparatus for performing electrodeposition onto a substrate, the apparatus comprising:
 a first electrode for connection to the substrate;   a second electrode; and   at least one ultrasound source;   wherein a region for containing the substrate is located between the first electrode and the ultrasound source.