Front Referenced Anode Positioning Mechanism for Electroplating
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Solution Overview
Problem
In electroplating, consumable anodes undergo shape changes during plating, leading to non-uniform metal deposition on semiconductor wafers due to changing distances between the anode and the work piece, which affects plating uniformity, especially for thin layers.
Innovation Solution
An anode support system with a positioning mechanism that maintains a consistent distance between the consumable anode and the work piece by adjusting the anode's position as it is consumed, using springs and hard stops to ensure a stable gap and apply upward force, allowing for continuous plating without significant changes in resistivity or power requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a consumable anode is used in electroplating, then the anode dissolves into the electrolyte to replenish metal ions, but the anode undergoes shape change and distance change from the work piece, leading to non-uniform plating
Solution Approach 1:
The anode is designed with a movable positioning mechanism that dynamically adjusts the anode's position during plating. As the anode consumes and thins, the positioning mechanism moves the anode to maintain a constant distance from the work piece, ensuring uniform plating throughout the process
Solution Approach 2:
The system changes the physical state of the anode support from static to dynamic, allowing continuous adjustment of the anode's spatial position. This parameter change compensates for the anode's consumption and maintains optimal plating conditions
2Device complexity
If the anode is allowed to consume naturally without positioning adjustment, then the plating process is simple, but the distance between anode and work piece changes, affecting electric field uniformity and plating quality
Solution Approach 1:
An intermediary positioning mechanism is introduced between the anode and the plating system structure. This mediator component automatically adjusts the anode's position, decoupling the anode consumption process from the distance variation that would otherwise occur
3Duration of action of moving object
If thicker anodes are used to extend plating duration, then anode life is extended, but the initial distance and positioning complexity increases
Solution Approach 1:
The positioning mechanism is designed to automatically compensate for anode consumption without external intervention. The system self-regulates the anode position throughout its service life, maintaining uniform plating conditions from initial installation until the anode is fully consumed
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 enhances plating uniformity by minimizing sensitivity to resistive variations and power changes, extends anode life, reduces the need for frequent replacements, and lowers the cost of ownership by maintaining a consistent gap, enabling the use of thicker anodes for longer periods without compromising uniformity.
Implementation Method 1
Electroplating uses electrical current to reduce cations of a desired material from a solution and coat a conductive object, the work piece, with a thin layer of the material, such as a metal
Implementation Method 2
At the cathode, the dissolved metal ions in the electrolyte solution are reduced at the surface of the cathode, such that they 'plate out' onto the cathode
Implementation Method 3
Metal atoms of the anode are oxidized to ions, allowing them to dissolve in the electrolyte
Implementation Method 4
In this manner, the ions in the electrolyte bath are continuously replenished by the anode
Implementation Method 5
the anode positioning mechanism includes: (i) a support plate, for supporting the consumable anode; and (ii) a drive component, configured to apply upward force to the support plate sufficient to raise the anode
Data Source
AI summary
Apparatus and methods for electroplating are described. Apparatus described herein include anode supports including positioning mechanisms that maintain a consistent distance between the surface of the wafer and the surface of a consumable anode during plating. Greater uniformity control is achieved. The consumable anode in one implementation has a plurality of through channels and at least one depression on its surface (e.g., a depression surrounding a channel) that is configured for registering with a protrusion on a component of an anode assembly, such as with a support plate. Fasteners may pass through the channels in the anode and attach it to a charge plate.