One-piece annular anode for electroplating edge uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In electroplating processes for semiconductor wafers, achieving uniform metal deposition across the substrate is challenging due to the terminal effect, where more metal is deposited at the edge regions, leading to non-uniformity and requiring manual adjustments of shielding elements for dissimilar substrates, which is impractical and causes downtime.
Innovation Solution
The introduction of a secondary anode with a generally annular body and protrusion of the same composition, positioned peripherally to the primary anode, allows for controlled plating current distribution without crossing the ion-permeable membrane, ensuring uniform metal deposition and accommodating dissimilar substrates without hardware changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a primary anode directly facing the substrate is used, then copper ions are supplied to the electrolyte, but non-uniform metal deposition occurs at the edge regions due to terminal effect
Solution Approach 1:
The anode system is segmented into a primary anode (for bulk copper ion supply) and a secondary annular anode (for edge region control). This segmentation allows independent control of plating current distribution, enabling uniform metal deposition across the substrate by addressing the terminal effect at edge regions through the secondary anode's peripheral positioning and separate power supply control.
Solution Approach 2:
The secondary annular anode is positioned peripherally to specifically address the edge regions where terminal effect occurs. By applying local quality control through separate power supply adjustment, the plating current distribution is optimized at the substrate edges while the primary anode maintains overall copper ion supply, achieving uniform deposition across different regions.
2Manufacturing precision
If shielding elements are manually adjusted for dissimilar substrates, then plating uniformity can be optimized, but production downtime increases
Solution Approach 1:
The secondary annular anode system provides dynamic control capability through its independent power supply, allowing real-time adjustment of plating current distribution for different substrate types without manual physical intervention. This dynamic electrical control replaces static manual shielding adjustments, enabling rapid reconfiguration between dissimilar substrates and eliminating production downtime.
Solution Approach 2:
The system changes operational parameters (plating current distribution) through the secondary anode's independent power supply to accommodate dissimilar substrates. By adjusting electrical parameters rather than physical shielding configurations, the system achieves optimal plating uniformity for different substrate types without manual intervention, maintaining high productivity.
3Ease of manufacture
If fasteners of different composition are attached to the anode, then electrical connection is achieved, but voltage fluctuations occur leading to plating non-uniformities
Solution Approach 1:
The anode structure uses fasteners made of the same composition as the annular anode body (copper, cobalt, or nickel). This homogeneity in material composition prevents galvanic corrosion and voltage fluctuations at the fastener-anode interface, ensuring stable plating conditions and uniform metal deposition while maintaining ease of manufacture through simplified assembly.
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 configuration stabilizes the plating environment, reduces voltage fluctuations, and achieves improved radial and azimuthal uniformity, enabling efficient processing of dissimilar substrates with minimal downtime by dynamically controlling the plating current.
Implementation Method 1
When an active (soluble) copper anode is used, the anode is dissolved during electroplating according to equation (1). The active anode can serve as a source of copper ions in the electrolyte. Cu-2e−→Cu2+
Implementation Method 2
When an active (soluble) copper anode is used, the anode is dissolved during electroplating according to equation (1). The active anode can serve as a source of copper ions in the electrolyte.
Implementation Method 3
The copper ions contained in the electrolyte are reduced at the cathodically biased substrate, such that copper is electrodeposited according to equation (2). Cu2++2e−→Cu
Implementation Method 4
The copper ions contained in the electrolyte are reduced at the cathodically biased substrate, such that copper is electrodeposited according to equation (2).
Data Source
AI summary
An active (consumable) anode includes, in one aspect, a generally annular body and a protrusion used for connecting the anode to the power supply, where the protrusion extends outward from the generally annular body of the anode. The compositions of the generally annular body and of the protrusion are the same, and, in some embodiments, the anode is a one-piece anode that does not include any welding seams. Such structure results in reduced voltage fluctuations during plating and in improved control over plating uniformity. In some embodiments, the anode is a copper anode, a cobalt anode, or a nickel anode machined from a single sheet of anode-grade metal. The provided anode can be used in an electroplating apparatus as a secondary, peripherally disposed anode, in conjunction with a more centrally located primary anode. The provided anode is configured to modulate electroplating at the edge of the substrate.