Conductive Sieve for Electrolyte Jet Boundary Layer Disruption
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Solution Overview
Problem
Existing electrochemical deposition techniques face challenges in achieving uniform plating and efficient mass transfer, leading to non-uniform boundary layers and reduced plating rates, especially when using precious metals like gold.
Innovation Solution
The proposed solution involves an electrochemical deposition apparatus with a disk-shaped, electrically neutral and conductive sieve that directs high-velocity jets of electrolyte toward a rotating semiconductor wafer, disrupting the boundary layer and enhancing ion replenishment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electrochemical deposition is used without boundary layer disruption, then the process is simple, but plating uniformity and mass transfer efficiency are poor
Solution Approach 1:
The patent employs a porous electrode structure with numerous pores that serve as outlets for electrolyte jets. This porous configuration allows electrolyte to be delivered uniformly across the electrode surface through many small jets, disrupting the boundary layer effectively while maintaining a relatively simple overall device structure. The porous material itself becomes the electrolyte delivery mechanism.
Solution Approach 2:
The electrolyte delivery system is segmented into multiple discrete jets emerging from the porous electrode surface. Instead of using a single complex flow distribution system, the electrolyte flow is divided into many smaller jets that are distributed across the electrode, each contributing to boundary layer disruption and improving plating uniformity.
2Productivity
If high electrolyte flow rate is used to improve mass transfer, then plating rate increases, but energy consumption and system complexity increase
Solution Approach 1:
The porous electrode structure enables efficient mass transfer at lower bulk electrolyte flow rates by utilizing the porous network to distribute and direct electrolyte flow precisely where needed. The porous structure acts as an internal flow distribution system that reduces energy losses associated with high-volume pumping while maintaining effective ion supply to the electrode surface.
Solution Approach 2:
The patent utilizes hydraulic principles by employing electrolyte jets emerging from the porous electrode to create localized high-velocity flows that disrupt the boundary layer. These jets are driven by pressure differential rather than requiring high bulk flow rates, thereby reducing energy consumption while maintaining effective mass transfer.
3Manufacturing precision
If conventional electrolyte flow is used, then the system is simple, but boundary layer thickness increases reducing plating quality
Solution Approach 1:
The porous electrode structure inherently provides multiple flow outlets that create distributed jets, eliminating the need for complex external flow control mechanisms. The porous material itself structures the electrolyte flow into numerous small jets that naturally disrupt the boundary layer, improving plating quality without adding significant device complexity.
Solution Approach 2:
The electrolyte flow is segmented into multiple discrete jets through the porous electrode structure, creating localized high-velocity flows that effectively disrupt the boundary layer. This segmentation is achieved passively through the porous material geometry rather than requiring active flow control systems.
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 results in faster and more uniform plating, as evidenced by testing where a 5 liter per minute electrolyte flow rate with the sieve achieves the same plating rate as a 60 liter per minute flow rate without the sieve.
Implementation Method 1
directs jets of electrolyte toward a workpiece that rotates within the chamber
Implementation Method 2
disrupt a boundary layer of electrolyte at a surface of the rotating semiconductor wafer
Implementation Method 3
metal ions in the solution are reduced at the silicon wafer's surface. This reduction process causes the metal ions to bond with the silicon substrate, forming a plated metal layer
Implementation Method 4
metal ions in the solution are reduced at the silicon wafer's surface
Implementation Method 5
a workpiece that rotates within the chamber
Data Source
AI summary
An electrochemical deposition fountain reactor for processing spinning semiconductor wafers can include a perforated ionic membrane near the wafer surface through which electrolyte flows. This allows high velocity electrolyte jets to impinge the wafer surface at low bulk flow rates, which reduces the boundary layer at the wafer surface and allows for better replenishment of ions at the wafer surface.