Electrochemical deposition systems with enhanced crystallization prevention features

Abstract

Electrochemical deposition systems and methods are described that have enhanced crystallization prevention features. The systems may include a bath vessel operable to hold an electrochemical deposition fluid having a metal salt dissolved in water. The systems may also include sensors including a thermometer and concentration sensor operable to measure characteristics of the electrochemical deposition fluid. The systems further include a computer configured to perform operations that include receiving system data from the electrochemical system and generating a control signal to change a characteristic of the electrochemical deposition fluid to prevent crystallization of a metal salt in the fluid. The computer generates the control signal based on processing that may include comparing an actual metal salt concentration in the electrochemical deposition fluid to a theoretical solubility limit for the metal salt in the fluid.

What is claimed is: 
     
         1 . A method to prevent precipitation of an electrodeposition salt in an electrochemical deposition system, the method comprising:
 measuring a temperature of an electrochemical deposition fluid in a bath vessel of the electrochemical deposition system;   measuring a metal salt concentration of a metal salt in the electrochemical deposition fluid;   generating system data from the electrochemical deposition system, wherein the system data comprises temperature data from the measuring of the temperature of the electrochemical deposition fluid and concentration data from the measuring of the concentration of the metal salt in the electrochemical deposition fluid; and   generating a control signal from a computer coupled to the electrochemical deposition system, wherein the control signal adjusts the concentration or the temperature of the metal salt in the electrochemical deposition fluid.   
     
     
         2 . The method of  claim 1 , wherein the control signal adjusts the temperature of the metal salt in the electrochemical deposition fluid by adjusting an amount of power delivered to a heater in thermal contact with the electrochemical deposition fluid. 
     
     
         3 . The method of  claim 1 , wherein control signal adjusts the concentration of the metal salt in the electrochemical deposition fluid by adjusting an amount of deionized water supplied to the electrochemical deposition fluid. 
     
     
         4 . The method of  claim 1 , wherein the electrochemical deposition fluid further comprises an acid characterized by an acid concentration, and wherein the system data further comprises acid concentration data from measuring the acid concentration of the electrochemical deposition fluid. 
     
     
         5 . The method of  claim 1 , wherein the method further comprises measuring a first power condition from a heater to heat the electrochemical deposition fluid in the bath vessel and measuring a second power condition from a pump to circulate the electrochemical deposition fluid in the bath vessel, and
 wherein the control signal generated by the computer comprises a drain signal to remove the electrochemical deposition fluid from the bath vessel based on the measurement of the first power condition and the second power condition.   
     
     
         6 . The method of  claim 1 , wherein the metal salt in the electrochemical deposition fluid comprises a copper salt, a nickel salt, or a gold salt. 
     
     
         7 . A non-transitory computer-readable medium comprising instructions that, when executed by one or more processors, cause one or more processors to execute operations comprising:
 receiving temperature data from a temperature sensor in thermal contact with an electrochemical deposition fluid in a bath vessel of an electrochemical deposition system;   receiving metal salt concentration data from a concentration sensor operable to measure a metal salt concentration in the electrochemical deposition fluid;   generating system data from the electrochemical deposition system, wherein the system data comprises the temperature data and the metal salt concentration data; and   generating a control signal based on the system data to adjust the temperature or the concentration of the metal salt in the electrochemical deposition fluid.   
     
     
         8 . The non-transitory computer-readable medium of  claim 7 , wherein the instructions, when executed by one or more processors, cause the one or more processors to execute operations comprising:
 receiving acid concentration data from an acid concentration sensor operable to measure an acid concentration in the electrochemical deposition fluid; and   generating the control signal based on additional system data that includes the acid concentration data.   
     
     
         9 . The non-transitory computer-readable medium of  claim 7 , wherein the instructions, when executed by one or more processors, cause the one or more processors to execute operations comprising:
 receiving electrochemical deposition fluid level data from a level sensor operable to measure an amount of the electrochemical deposition fluid in the bath vessel; and   generating the control signal based on additional system data that includes the electrochemical deposition fluid level data.   
     
     
         10 . The non-transitory computer-readable medium of  claim 7 , wherein the instructions, when executed by one or more processors, cause the one or more processors to execute operations comprising:
 receiving power status data from a first power sensor operable to detect if a heater is heating the electrochemical deposition fluid and a second power sensor operable to detect if a pump is circulating the electrochemical deposition fluid in the bath vessel; and   generating the control signal comprising a drain signal based on the power status data.   
     
     
         11 . The non-transitory computer-readable medium of  claim 7 , wherein the instructions, when executed by one or more processors, cause the one or more processors to execute operations comprising:
 generating from the system data an actual metal salt concentration in the electrochemical deposition fluid, and comparing the actual metal salt concentration to a theoretical solubility limit for the metal salt in the electrochemical deposition fluid; and   generating the control signal based on the comparing of the actual metal salt concentration to the theoretical solubility limit for the metal salt.   
     
     
         12 . The non-transitory computer-readable medium of  claim 11 , wherein the theoretical solubility limit is generated by the computer based on the temperature of the electrochemical deposition fluid and a solubility constant of the metal salt in water.