Adjustable Anode Mask Layout for Uniform Plating on Polygonal Substrates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The in-plane uniformity of film thickness on polygonal substrates is compromised due to the terminal effect, resulting in uneven plating distribution, particularly near corner portions and center regions, which is exacerbated by variations in resist opening rates and plating solution conditions.
Innovation Solution
A plating apparatus and method that utilizes an anode mask with adjustable mask members projecting towards the center of the substrate, allowing for controlled adjustment of the distance between these mask members to mitigate the terminal effect and enhance film uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrical contact points are disposed at peripheral edge portions of a polygonal substrate with a regulation plate and anode mask having openings with similar shapes, then the terminal effect occurs substantially uniformly over the periphery, but film thickness distribution becomes non-uniform with singular points near corner portions
Solution Approach 1:
The patent applies asymmetry by configuring the anode mask opening shape to differ from the substrate shape. Specifically, for a quadrangular substrate, the anode mask has a circular opening that does not correspond to the corner portions, thereby eliminating the terminal effect concentration at corners and achieving uniform film thickness distribution across the substrate surface.
Solution Approach 2:
The patent changes the geometric parameter of the anode mask opening from a polygonal shape matching the substrate to a circular shape. This parameter change in the opening geometry fundamentally alters the electric field distribution, preventing the formation of singular points at corner portions and achieving uniform plating thickness.
2Manufacturing precision
If the anode mask opening size is adjusted to compensate for terminal effect, then film thickness uniformity may be improved in some regions, but corner portions and center portions exhibit significantly different thickness trends that cannot be sufficiently improved
Solution Approach 1:
The patent resolves the adaptability issue by using a circular anode mask opening that is asymmetric relative to the polygonal substrate. This asymmetric configuration eliminates the corner effect entirely, making the plating process adaptable to various polygonal substrate shapes and sizes without requiring complex adjustments to mask opening dimensions.
Solution Approach 2:
The circular anode mask opening design provides universality by being applicable to different polygonal substrate configurations. The same circular mask geometry can be used for various substrate shapes (triangular, quadrangular, pentagonal, etc.), making the system versatile and eliminating the need for substrate-specific mask designs.
3Manufacturing precision
If a circular substrate is used for plating, then the terminal effect occurs uniformly over the periphery, but the film thickness at the center portion becomes thinner than at the peripheral edge portions
Solution Approach 1:
The patent applies asymmetry by using a circular anode mask opening with a diameter larger than the inscribed circle of the polygonal substrate. This creates an asymmetric electric field distribution that compensates for the terminal effect, directing more current toward the center portion and achieving uniform film thickness across the entire substrate surface.
Solution Approach 2:
The patent changes the critical parameter of the anode mask opening diameter to be larger than the substrate's inscribed circle diameter. This parameter change ensures that the electric field is properly distributed across the polygonal substrate, preventing center portion thinning while maintaining peripheral uniformity.
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 apparatus achieves improved in-plane uniformity of the plating film thickness on polygonal substrates by adjusting the anode mask's opening shape, effectively reducing thickness variations across the substrate surface.
Implementation Method 1
This phenomenon that a metal ion reduction current, that is, a plating current concentrates on the peripheral edge portions of the substrate due to a potential difference between the substrate center and the peripheral edge portions is called a terminal effect.
Implementation Method 2
the electrolytic plating method which enables miniaturization and relatively stable performance has been increasingly used
Implementation Method 3
the potential gradually drops by the amount corresponding to an electric resistance of the seed layer
Data Source
AI summary
To improve in-plane uniformity of a film to be plated on a polygonal substrate. A plating apparatus includes: a plating tank; a substrate holder configured to hold a polygonal substrate; an anode disposed inside the plating tank such that the anode faces the substrate held by the substrate holder; and an anode mask defining an opening corresponding to an outer shape of the polygonal substrate. The anode mask includes a first mask member defining a first projecting portion projecting toward a center of the opening at a center portion of a first opening side of the opening corresponding to a first side of the polygonal substrate and a second mask member defining a second projecting portion projecting toward the center of the opening at a center portion of a second opening side of the opening corresponding to a second side of the polygonal substrate, and is configured to be able to adjust a mutual distance between the first mask member and the second mask member.