Simultaneous Inhibitor Analysis in Plating Baths
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Solution Overview
Problem
Current methods for analyzing electroplating baths fail to accurately determine the concentrations of multiple inhibitors simultaneously, leading to significant errors in maintaining appropriate additive concentrations during mass production, which results in reduced product yield.
Innovation Solution
A method using different electrical load conditions to determine the concentrations of at least two inhibitors by applying calibration curves based on deposition rate ratios, allowing for simultaneous analysis of inhibitors like levelers and suppressors in a plating bath.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional analytical methods are used to determine inhibitor concentrations, then the analysis can be performed, but the measurement precision is poor with errors up to 43%
Solution Approach 1:
The patent segments the analysis process into two distinct phases: first determining the suppressor concentration using cyclic voltammetric stripping, then using that result as background to determine the leveler concentration. This sequential segmentation allows each inhibitor to be measured with appropriate precision without mutual interference, reducing measurement errors from 43% to under 5% and thereby improving product yield
Solution Approach 2:
The patent performs preliminary determination of suppressor concentration before measuring leveler concentration. The suppressor analysis is conducted first, and the resulting measurement solution is adjusted to a predetermined suppressor concentration that serves as the background for subsequent leveler analysis. This preliminary action eliminates the need for separate background subtraction and reduces cumulative measurement errors
2Productivity
If sequential analysis methods are used for suppressor and accelerator, then the analysis can be completed, but the productivity is reduced due to multiple separate analyses
Solution Approach 1:
The patent merges the determination of suppressor and leveler concentrations into a single integrated analytical sequence. Both inhibitors are analyzed in one continuous process using the same electrochemical cell without cleaning or rinsing between measurements. The suppressor concentration is determined first, then the leveler concentration is determined in the same solution, effectively combining two separate analyses into one operational cycle and improving productivity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides accurate, fast, and cost-effective on-line feedback control for maintaining inhibitor concentrations within pre-defined limits, significantly reducing errors from 43% to less than 5%, thereby improving product yield.
Implementation Method 1
Cyclic voltammetric stripping (CVS) methods are used to measure the concentrations of the suppressor and anti-suppressor based on the effects of these additives on the copper electrodeposition rate
Implementation Method 2
The method uses measurements of the copper electrodeposition rate to determine the concentration of the leveler additive
Data Source
AI summary
The presently claimed invention provides an accurate, fast, and cost effective method for determining the additive concentrations of at least two inhibitors simultaneously in an electroplating bath by using different electrical load conditions. The method of the present invention is able to determine additive concentrations of different inhibitors effectively during on-line feedback control for adjusting the amount of additives in the electroplating bath to maintain the additive concentrations within pre-defined limits during device production.