Detecting Additive Breakdown in Acid Copper Plating Baths
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Solution Overview
Problem
Current methods lack an effective way to detect leveler additive breakdown products in acid copper plating baths, which can degrade deposit properties and interfere with the functioning of the additive system, making it difficult to control the leveler additive at the optimum level.
Innovation Solution
A method involving voltammetric analysis in two measurement solutions with different volume fractions of the copper plating bath sample, comparing the copper electrodeposition rate parameters to determine the concentration of additive breakdown products, using cyclic voltammetric stripping (CVS) and a calibration curve to provide accurate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional CVS analysis methods are used to control additive concentrations, then the deposit properties can be maintained, but breakdown products of leveler additives cannot be detected and controlled
Solution Approach 1:
The patent segments the analysis into two distinct measurement steps: first measuring the copper electrodeposition rate parameter in a measurement solution containing the plating bath sample, then measuring the rate parameter after adding a known amount of leveler additive. By comparing these two measurements, the method specifically detects leveler breakdown products that interfere with leveler detection, while conventional CVS methods measure only the total electrodeposition rate without distinguishing between different additive effects.
Solution Approach 2:
The patent applies local quality by creating a specific measurement condition where the interference from breakdown products is isolated and measured. The measurement solution is prepared with specific components (plating bath sample, background electrolyte, suppressor additive, anti-suppressor additive) to create a controlled environment where leveler detection interference can be specifically identified without being masked by other bath components.
2Reliability
If leveler additive concentration is increased to compensate for breakdown products, then deposit quality may be maintained, but breakdown product concentration increases further degrading deposit properties
Solution Approach 1:
The patent implements feedback control by providing a quantitative measurement of leveler breakdown product concentration that can be used to adjust the leveler additive dosing strategy. The measured breakdown product concentration feeds back to the control system, enabling operators to optimize leveler addition rates to maintain effective leveler concentration without excessive breakdown product accumulation, thus preventing the vicious cycle of increasing additive to compensate for degradation.
Solution Approach 2:
The patent replaces empirical trial-and-error additive dosing with a scientific measurement and calculation system. Instead of mechanically increasing additive concentration to compensate for unknown breakdown, the system uses electrochemical measurement and mathematical calculation to precisely determine breakdown product concentration and guide optimal additive dosing decisions.
3Manufacturing precision
If empirical trial-and-error methods are used to control leveler concentration, then some deposit quality can be achieved, but precise control of breakdown product concentration is impossible
Solution Approach 1:
The patent uses the copper electrodeposition rate parameter as an intermediary measurement that indirectly quantifies leveler breakdown product concentration. Rather than directly measuring breakdown products (which would require complex analytical chemistry), the method uses the electrochemical response of copper deposition as a mediator to detect and quantify the presence and concentration of breakdown products interfering with leveler function.
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
Enables precise detection and control of leveler additive concentrations, preventing excessive breakdown product concentrations that can degrade deposit properties, thereby improving the quality of copper plating deposits.
Implementation Method 1
Cyclic voltammetric stripping (CVS) analysis is the most widely used bath additive control method and involves cycling the potential of an inert electrode (e.g., Pt) in the plating bath between fixed potential limits so that metal is alternately plated on and stripped from the electrode surface.
Implementation Method 2
the copper electrodeposition rate parameter reflects the rate of copper electrodeposition from the measurement solution under predetermined conditions
Data Source
AI summary
An additive breakdown product in an acid copper plating bath sample is detected by performing a voltammetric analysis for the leveler additive in two measurement solutions comprising different volume fractions of the copper plating bath sample in a background electrolyte. When the plating bath sample contains a substantial concentration of the additive breakdown product, the analyses for the first and second measurement solutions indicate different concentrations for the leveler additive in the plating bath sample. A comparison of the leveler additive concentrations indicated by the two analyses provides a measure of the concentration of the additive breakdown product.