Substrate Holder Seal Ring Opening Ratio for Plating Uniformity
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Solution Overview
Problem
The existing cup-type electroplating apparatuses do not adequately address the impact of the seal and seal holder configuration on the uniformity of the plating film thickness, as the difference in opening diameters between the seal and the seal holder affects the electric field density, leading to non-uniform plating film thickness.
Innovation Solution
A substrate holder is designed with a seal and a seal ring holder where the opening diameter ratio of the seal ring holder to the seal is between 99.32% and 99.80%, optimizing the balance of electric field restriction and spread to enhance the uniformity of the plating film thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the opening diameter of the seal holder is made smaller than the opening diameter of the seal to allow appropriate holding, then the seal is properly secured, but the uniformity in the thickness of the plating film deteriorates due to altered electric field density
Solution Approach 1:
The invention changes the geometric parameters of the seal holder by providing a tapered surface that extends from the opening edge toward the seal, creating intermediate opening diameters between the seal holder opening and seal opening. This gradual parameter transition optimizes the electric field distribution while maintaining secure seal holding.
Solution Approach 2:
The invention applies local quality by creating a tapered surface with varying opening diameters at different locations. The taper ratio is specifically controlled (0.01 to 0.1 per mm axial length) to achieve optimal electric field distribution in the critical region between the seal and substrate, while maintaining the structural integrity of the seal holder.
2Manufacturing precision
If additional components are added to adjust the electric field, then the plating film thickness uniformity can be improved, but the device complexity increases
Solution Approach 1:
The invention makes the seal holder multi-functional by integrating the electric field adjustment function directly into its structure. The tapered surface on the seal holder simultaneously serves as a structural component for holding the seal and as an electric field modulation element, eliminating the need for separate adjustment components.
Solution Approach 2:
The invention merges the seal holding function and the electric field adjustment function into a single integrated component - the seal holder. The tapered surface configuration combines structural support with electric field optimization, reducing the number of parts and simplifying the overall apparatus.
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 configuration significantly improves the in-plane uniformity of the plating film thickness, particularly in the outer peripheral regions of the substrate, without the need for additional components to adjust the electric field, thereby enhancing the overall plating process efficiency.
Implementation Method 1
the density of electric lines of force (electric field) to the plating surface of the substrate during plating affects the uniformity in the thickness of the plating film
Implementation Method 2
applies a voltage between the substrate and anode to make a conductive film (plating film) deposit on a surface of the substrate
Data Source
AI summary
There is provided a substrate holder configured to hold a substrate in an apparatus for plating. The substrate holder comprises a seal configured to seal an outer peripheral part of the substrate and provided with a first opening which a surface to be plated or a plating surface of the substrate is exposed on; and a seal ring holder configured to hold the seal and provided with a second opening which the plating surface of the substrate is exposed on, wherein an opening diameter ratio that is a ratio of an opening diameter of the second opening to an opening diameter of the first opening is in a range of not lower than 99.32% and not higher than 99.80%.