Secondary Weir for Uniform Electroplating Overflow
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Solution Overview
Problem
Current electroplating processes face challenges in achieving uniform overflow of plating solution, leading to defects in the deposited metal layer on wafers due to non-uniform fluid behavior and bubble clearance issues, which are difficult to replicate across different electroplating cells.
Innovation Solution
The implementation of a secondary weir positioned below the primary weir in the electroplating cell ensures uniform overflow by allowing plating solution to pool and flow over the secondary weir, promoting radial and uniform fluid exit paths, thereby reducing defects and improving reproducibility of fluid behavior across different setups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a primary weir is used for plating solution overflow, then the plating solution can exit the chamber, but the overflow is non-uniform leading to defects in the deposited metal layer
Solution Approach 1:
The single primary weir is segmented into two functional weirs: a primary weir for collecting overflow and a secondary weir positioned below it for uniform distribution. This segmentation allows the system to separate the collection function from the distribution function, achieving both efficient liquid removal and uniform flow distribution across the chamber.
Solution Approach 2:
The secondary weir acts as an intermediary element between the primary weir and the chamber bottom. It receives overflow from the primary weir and mediates the flow distribution to create uniform radial flow patterns, eliminating the non-uniform overflow that causes defects while maintaining effective bubble clearance.
2Productivity
If plating solution flows directly over the primary weir, then liquid can be removed efficiently, but non-uniform fluid behavior causes defects
Solution Approach 1:
The overflow removal process is segmented into two stages: first, the primary weir efficiently collects bulk overflow; second, the secondary weir distributes this flow uniformly across the chamber. This segmentation maintains high liquid removal efficiency while adding the uniform distribution function needed for defect-free deposition.
Solution Approach 2:
The secondary weir is positioned in a different vertical dimension below the primary weir, creating a two-level overflow system. This vertical dimensionality allows the system to maintain efficient liquid removal at the upper level while achieving uniform flow distribution at the lower level, resolving the contradiction between productivity and manufacturing precision.
3Ease of operation
If the electroplating cell is tilted to improve flow, then bubble clearance may improve, but fluid behavior becomes non-reproducible across different cells
Solution Approach 1:
The dual-weir system creates an equipotential overflow surface that equalizes flow distribution across the chamber. By positioning the secondary weir below the primary weir, the system establishes a consistent flow potential that produces reproducible radial flow patterns regardless of cell tilt, eliminating the variability associated with tilted cell operations.
Solution Approach 2:
The invention changes the geometric parameters of the overflow system by adding a second weir at a different vertical position. This parameter change transforms the flow regime from non-reproducible (affected by tilt) to reproducible (controlled by the fixed dual-weir geometry), while maintaining effective bubble clearance through the established flow patterns.
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 use of a secondary weir significantly reduces bubble clearance times and ensures uniform radial overflow, resulting in defect-free and reproducible metal deposition on wafers, even in tilted electroplating cells, and improves the overall efficiency of the electroplating process.
Implementation Method 1
the overflowed plating solution can pool and remain in contact with the plating solution overflowing the primary weir, whereby the plating solution flows over the primary weir in a substantially azimuthally uniform manner
Implementation Method 2
Depositing a metal layer onto a wafer, also known as 'electroplating' or 'electrodeposition,' is often a critical step in manufacturing an integrated circuit or semiconductor device
Data Source
AI summary
Apparatuses and methods are provided for depositing a metal layer on a wafer. A secondary weir is positioned at a region below the primary weir such that overflowed plating solution over the primary weir during electroplating flows in a substantially azimuthally uniform manner. Methods are provided for electroplating wafers by increasing flow rate between wafer processes while plating solution flows over a primary weir, remains in contact with the overflowing plating solution, and flows onto the secondary weir such that overflow is substantially azimuthally uniform.