Plating Current Control Using Voltage Change at Limiting Current Density
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Solution Overview
Problem
In plating apparatuses, increasing current density to reduce plating time can lead to abnormal deposition due to uncertainties in limiting current density, which may be underestimated due to solution density changes or operational errors, resulting in excessive current density application before inspection.
Innovation Solution
A method and apparatus that monitor voltage changes during current density increments to determine if the current density has reached or exceeded the limiting current density, adjusting the plating process to prevent abnormal deposition by controlling current values and durations based on measured voltage thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the current density is increased to reduce plating time, then productivity is improved, but abnormal deposition occurs when the current density exceeds the limiting current density
Solution Approach 1:
The patent implements a feedback control system that continuously monitors the voltage across the substrate during plating. When the voltage exceeds a predetermined threshold, indicating that the current density has reached the limiting current density, the system automatically adjusts the current density to remain at or below the limiting value. This prevents abnormal deposition while maximizing plating speed by operating at the highest safe current density.
2Productivity
If the current density is set close to the limiting current density to reduce plating period, then productivity is improved, but the risk of exceeding limiting current density increases due to uncertainties in determining the exact limiting current density
Solution Approach 1:
The system uses real-time voltage monitoring to dynamically determine and control the limiting current density during plating operations, rather than relying on pre-determined fixed values. This feedback mechanism allows the system to adapt to variations in plating conditions and accurately maintain operation at the true limiting current density, improving both reliability and productivity.
Solution Approach 2:
The patent transitions from a static, pre-determined current density approach to a dynamic control system that continuously adjusts the current density based on real-time voltage measurements. This dynamic adjustment allows the system to respond to changing plating conditions and maintain optimal current density throughout the plating process, reducing the risk of exceeding the limiting current density.
3Use of energy by stationary object
If the current density is increased to shorten plating time, then energy consumption is reduced, but the supply of metal ions to the substrate surface becomes insufficient
Solution Approach 1:
The voltage monitoring system provides feedback on the metal ion supply status at the substrate surface. When the voltage increases, indicating insufficient metal ion supply, the system automatically reduces the current density to a level where metal ion supply is adequate. This ensures efficient energy utilization by operating at the maximum current density that maintains sufficient metal ion supply.
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 allows for real-time determination of current density levels, preventing excessive current application and maintaining film quality by adjusting current values and durations, thereby ensuring consistent plating without abnormal deposition.
Implementation Method 1
an electroplating apparatus that includes a plating bath, which internally houses a plating solution, a substrate and an anode
Implementation Method 2
measuring a voltage value applied to the substrate
Data Source
AI summary
A plating method for plating a substrate by increasing a current value from a predetermined current value to a first current value is provided. The plating method plates the substrate for a first predetermined period with the first current value when a first current density corresponding to the first current value is lower than a limiting current density. This plating method includes measuring a voltage value applied to the substrate, and when the current value is increased from the predetermined current value to the first current value, determining whether the first current density is equal to or more than the limiting current density or not based on an amount of change in the voltage value.