Flow-through Edge Shield for Wafer Electroplating Current Crowding
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Solution Overview
Problem
Current electroplating processes face challenges with current crowding at the wafer edge due to larger gaps between the wafer and edge shields, leading to high edge current densities and deposition rates, which can result in non-uniform edge plating.
Innovation Solution
The introduction of an edge shield with one or more rings disposed below the wafer edge, configured to restrict current flow to the edge of the wafer while allowing electrolyte flow to pass through, effectively reducing current crowding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a gap between the wafer and chamber walls is maintained to allow flow exit, then mass transfer is improved, but current crowding at the wafer edge increases
Solution Approach 1:
An edge shield is introduced as an intermediary component between the wafer and chamber walls. The edge shield includes openings that allow controlled electrolyte flow while its body blocks excessive current paths, mediating between the conflicting requirements of mass transfer and current distribution
Solution Approach 2:
The edge shield provides localized modification of the electroplating environment at the wafer edge region. By placing the shield specifically at the edges where current crowding occurs, it locally alters current distribution without affecting the overall mass transfer to the entire wafer surface
2Manufacturing precision
If conventional weir shields are used to protect against current crowding, then current density uniformity is improved, but mass transfer to the wafer edge is blocked
Solution Approach 1:
The edge shield incorporates openings that function similarly to porous structures, allowing selective passage of electrolyte flow while maintaining the shielding effect against excessive current. The openings enable mass transfer while the solid portions of the shield block harmful current paths
3Manufacturing precision
If the chamber outer walls are aligned with the wafer edge to minimize current crowding, then current density uniformity is improved, but flow exit is blocked
Solution Approach 1:
The edge shield segments the gap between the wafer and chamber walls into controlled flow paths through its openings. This segmentation allows the shield to maintain current blocking function while providing dedicated channels for electrolyte flow exit
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 edge shield system achieves a more uniform current density distribution across the wafer, reducing edge current crowding and enhancing plating uniformity, thereby improving the overall quality of the electroplated film.
Implementation Method 1
mass-transfer determines the availability of cupric (Cu++) ions and additives at the plating surface. Plating consumes Cu++ ions at the surface, which must be replenished via mass-transfer
Implementation Method 2
Current density flows from the anode through the jet array to the wafer
Data Source
AI summary
An edge shield for reducing electrical current crowding of a wafer, having a first side and a second side, during jet array electroplating, including one or more rings disposed below a second side of the wafer and configured to restrict current flow to an edge of the wafer, and at least one opening configured to allow electrolyte flow to pass through. Further, a system for reducing electrical current crowding of a wafer during jet array electroplating, including a chamber where, when the wafer is placed inside the chamber, there is a first gap between a wall of the chamber and an edge of the wafer and a second gap between a jet array and the second side of the wafer, and an edge shield disposed in the second gap, wherein the edge shield includes at least one opening configured to allow electrolyte flow to escape the chamber.