Dissolved Gas Control in Electroplating Baths
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Solution Overview
Problem
In electrochemical deposition processes for semiconductor manufacturing, controlling the concentration of dissolved gases in electroplating solutions is challenging due to the adverse effects of excessive or insufficient dissolved gas, which can lead to wafer defects and chemical corrosion, necessitating precise control to maintain a sub-saturation concentration.
Innovation Solution
A degassing device, such as a contactor, is used to control the dissolved gas concentration by adjusting pressure, employing a vacuum source and gas-liquid separation membranes to maintain an intermediate concentration, with feedback from sensors to ensure optimal conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dissolved gas concentration is increased to prevent chemical corrosion, then corrosion resistance is improved, but wafer defects increase due to excessive dissolved gas
Solution Approach 1:
The patent applies parameter changes by precisely controlling the dissolved gas concentration within a specific range (0.5-5 ppm for oxygen in copper electroplating). This involves changing the concentration parameter from either too low or too high to an optimal intermediate value, resolving the contradiction between preventing corrosion (which requires sufficient gas) and avoiding wafer defects (which require limiting gas concentration). The control system dynamically adjusts aeration and degassing parameters to maintain this precise concentration window.
2Manufacturing precision
If dissolved gas concentration is decreased to prevent wafer defects, then manufacturing precision is improved, but chemical corrosion increases due to insufficient dissolved gas
Solution Approach 1:
The system resolves this contradiction by changing the dissolved gas concentration parameter to an optimal intermediate range rather than simply minimizing it. The control methodology monitors and adjusts aeration and degassing parameters to maintain gas concentration between 0.5-5 ppm, which is sufficient to prevent corrosion but low enough to prevent wafer defects. This precise parameter control simultaneously achieves both manufacturing precision and corrosion protection.
3Reliability
If aeration is increased to maintain dissolved gas concentration, then corrosion protection is improved, but energy consumption increases
Solution Approach 1:
The patent employs feedback control by using dissolved gas concentration sensors to monitor the actual gas levels in the electroplating solution. The control system receives this feedback and dynamically adjusts the aeration rate accordingly - increasing aeration only when gas concentration falls below the target range (0.5-5 ppm) and reducing or stopping aeration when the range is maintained. This feedback mechanism prevents excessive aeration and optimizes energy consumption while ensuring adequate corrosion protection.
4Manufacturing precision
If continuous monitoring and control of dissolved gas concentration is implemented, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent implements feedback control using dissolved gas concentration sensors that continuously monitor the gas levels and provide real-time data to the control system. This feedback loop enables precise maintenance of the 0.5-5 ppm concentration range without requiring overly complex control algorithms. The system automatically adjusts aeration and degassing based on sensor feedback, achieving high manufacturing precision through a relatively straightforward closed-loop control architecture that balances complexity with effectiveness.
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 effectively regulates dissolved gas levels, preventing defects and corrosion, while ensuring adequate control of reactive species like Cu1+, thereby enhancing the uniformity and efficiency of the electroplating process.
Implementation Method 1
A degassing device, such as a contactor, is used to control the dissolved gas concentration by adjusting pressure
Implementation Method 2
employing a vacuum source and gas-liquid separation membranes to maintain an intermediate concentration
Data Source
AI summary
A concentration of a dissolved gas can be controlled by following an electroplating solution through a contactor, controlling a pressure within the contactor, and thereby maintaining the concentration of the dissolved gas in the electroplating solution within a first concentration range. The first concentration range is non-zero and sub-saturation.