Oscillating Flow Agitation for Electroplating Uniformity
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Solution Overview
Problem
In semiconductor processing, achieving uniform high strain rates during electroplating is challenging due to non-uniform mass transfer across large substrates, leading to plating non-uniformities and increased complexity and costs in equipment design.
Innovation Solution
The implementation of an oscillating flow system across the wafer substrate, using mechanisms like pistons or moving walls to expel and intake liquid electrolyte, creating high and uniform strain rates without the need for agitators, which simplifies electric field control and reduces equipment complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high flow strain rates are used to achieve high mass transfer for plating megapillars, then plating rate and mass transfer are improved, but flow uniformity across the substrate deteriorates, resulting in plating non-uniformities
Solution Approach 1:
The patent employs dynamic flow control by oscillating the electrolyte flow direction periodically between opposite directions. This dynamic approach allows the system to achieve high instantaneous flow rates for mass transfer while the oscillation ensures uniformity across the substrate by alternating which regions receive highest flow intensity, preventing localized non-uniformities that would occur with steady unidirectional high-speed flow
Solution Approach 2:
The system implements periodic flow oscillation where the electrolyte flow direction is reversed at regular intervals. This periodic action ensures that all regions of the substrate are exposed to high flow rates alternately, maintaining uniform mass transfer across the entire substrate surface while still achieving the high overall mass transfer rates needed for high plating rates in megapillar structures
2Productivity
If traditional agitation systems are used to achieve high mass transfer, then plating rate is improved, but equipment complexity and cost increase
Solution Approach 1:
The patent removes traditional mechanical agitation components (agitators, paddles, impellers) from the system and replaces them with a flow oscillation mechanism. This extraction of complex mechanical agitation systems while maintaining high mass transfer through controlled electrolyte flow oscillation directly reduces equipment complexity and cost while preserving the ability to achieve high plating rates
Solution Approach 2:
The system replaces mechanical agitation systems with a fluid dynamics-based oscillation approach. Instead of using mechanical devices to agitate the electrolyte, the patent uses controlled flow direction changes and pressure gradients to achieve the same mass transfer enhancement, substituting a simpler fluid control system for complex mechanical agitation equipment
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 enables uniform plating across large substrates with high strain rates, improving plating quality and rate, reducing equipment costs, and enhancing reliability by maintaining uniform electric field and current density.
Implementation Method 1
oscillating flow across the wafer substrate during plating. The flow of the liquid electrolyte may include a uniform or substantially uniform strain rate near the wafer or other substrate
Implementation Method 2
High strain rates may be achieved, allowing plating into high aspect vias, trenches, or other features. High strain rates can help improve the shape of features being plated on a substrate, enhance additive transport and metal ions into features
Implementation Method 3
electrochemically plating metal onto the substrate while flowing the electrolyte in the first direction and while flowing the electrolyte in the second direction
Data Source
AI summary
Systems and methods for electroplating are described. The electroplating system may include a vessel configured to hold a first portion of a liquid electrolyte. The system may also include a substrate holder configured for holding a substrate in the vessel. The system may further include a first reservoir in fluid communication with the vessel. In addition, the system may include a second reservoir in fluid communication with the vessel. Furthermore, the system may include a first mechanism configured to expel a second portion of the liquid electrolyte from the first reservoir into the vessel. The system may also include a second mechanism configured to take in a third potion of the liquid electrolyte from the vessel into the second reservoir when the second portion of the liquid electrolyte is expelled from the first reservoir. Methods may include oscillating flow of the electrolyte within the vessel.