Seal Ring Design for Electroplating Uniformity
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Solution Overview
Problem
Existing electroplating processes face challenges with non-uniform metal plating due to 'plate-up' on electrical contacts and seal rings, which require additional steps to remove and can lead to reduced substrate usage and inconsistent electroplating quality, as well as seal failure and sticking issues.
Innovation Solution
A new seal ring design that minimizes contact area and ensures consistent, precise sealing with minimal slipping or deflection, using a combination of a rigid support ring and a molded seal material like Viton fluoroelastomer, with specific geometric features to prevent sliding and maintain sealing integrity across various wafer surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seal ring is used to prevent plate-up on electrical contacts, then plate-up is avoided, but the seal ring itself can plate up over successive cycles
Solution Approach 1:
The patent introduces an intermediary substance (release agent or coating) between the seal ring and the wafer surface to prevent direct metal deposition on the seal ring while maintaining the sealing function. This mediator layer allows the seal ring to perform its sealing duty without becoming a target for plate-up.
Solution Approach 2:
The patent modifies the surface properties of the seal ring by applying coatings or changing material composition to alter its electrochemical characteristics. This parameter change makes the seal ring surface less susceptible to metal deposition while preserving its sealing capability.
2Reliability
If the seal ring contacts a larger area of the substrate surface, then sealing is more reliable, but the usable substrate surface area is reduced
Solution Approach 1:
The patent employs a flexible seal ring made of elastomeric material that can conform to the wafer surface with minimal contact pressure and area. This flexible film approach provides reliable sealing while minimizing the footprint on the usable substrate surface.
Solution Approach 2:
The seal ring is constructed from composite materials combining elastomeric sealing properties with non-stick surface characteristics. This composite structure enables effective sealing with reduced adhesion and minimal substrate contact area.
3Manufacturing precision
If the seal ring is made rigid to provide precise sealing dimensions, then sealing precision is improved, but the seal ring may stick to the wafer after plating
Solution Approach 1:
The patent uses a flexible elastomeric seal ring that maintains precise sealing dimensions through its inherent elasticity and compliance. The flexibility prevents sticking by allowing the seal to release cleanly from the wafer surface after plating cycles.
Solution Approach 2:
The seal ring combines rigid structural support with a flexible non-stick sealing surface. This composite construction provides dimensional precision while the elastomeric outer layer prevents adhesion and sticking during the plating process.
4Adaptability or versatility
If the seal ring slips or deflects laterally on the wafer surface, then it may accommodate surface variations, but the sealing consistency is degraded
Solution Approach 1:
The flexible elastomeric seal ring naturally accommodates wafer surface variations through its compliance while maintaining consistent sealing pressure. The material's elasticity allows it to conform to slight surface irregularities without lateral slipping or deflection.
Solution Approach 2:
The seal ring design distributes contact pressure uniformly across its circumference, creating equipotential sealing conditions. This uniform pressure distribution allows the seal to adapt to surface variations while maintaining consistent sealing performance throughout the wafer perimeter.
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
The new seal ring design enhances electroplating uniformity and yield by reducing plate-up, minimizing substrate area usage, and maintaining reliable sealing over multiple cycles with reduced risk of sticking and leakage, thereby improving the overall quality and efficiency of the electroplating process.
Implementation Method 1
a seal ring seals the electrolyte away from the electrical contacts
Implementation Method 2
Metal ions in the electrolyte deposit or plate out onto the substrate, creating a metal layer on the substrate
Implementation Method 3
Electrical current is passed through the electrolyte and the conductive layer
Data Source
AI summary
A seal ring for an electrochemical processor does not slip or deflect laterally when pressed against a wafer surface. The seal ring may be on a rotor of the processor, with the seal ring having an outer wall joined to a tip arc through an end. The outer wall may be a straight wall. A relatively rigid support ring may be attached to the seal ring, to provide a more precise sealing dimension. Knife edge seal rings that slip or deflect laterally on the wafer surface may also be used. In these designs, the slipping is substantially uniform and consistent, resulting in improved performance.