Cross Flow Manifold Electroplating Uniformity
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Solution Overview
Problem
Current electroplating technologies face challenges in achieving uniform mass transfer and plating rates for small microbump and TSV features due to the formation of flow eddies and stagnation, leading to non-uniformity and reduced efficiency in copper, nickel, and other metal plating processes, particularly in wafer level packaging and TSV applications.
Innovation Solution
The implementation of a cross flow manifold system with a channeled ionically resistive element that generates cross-flowing electrolyte by combining upward and lateral fluid flows, creating a shearing force on the substrate to enhance mass transfer and plating uniformity, utilizing a mechanism for independent control of electrolyte flow rates and flow directing elements to maintain uniformity across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electroplating is used for small microbump and TSV features, then the plating process can be performed, but flow eddies and stagnation occur leading to non-uniform mass transfer and reduced plating uniformity
Solution Approach 1:
The patent introduces a cross-flow dimension by combining upward flow through the channeled plate with lateral flow across the substrate. This two-dimensional flow pattern prevents the formation of flow eddies and stagnation zones that occur with conventional single-direction flow, thereby achieving uniform mass transfer and improved plating uniformity across the substrate surface.
Solution Approach 2:
The patent employs hydraulic principles by using a channeled ionically resistive element to generate controlled upward fluid flow through the electrolyte. This hydraulic approach, combined with lateral flow, creates a cross-flow pattern that enhances mass transfer and eliminates flow stagnation, directly addressing the uniformity problem in small feature plating.
2Productivity
If higher flow rates are used to improve mass transfer, then plating rate increases, but flow instability and eddies form reducing uniformity
Solution Approach 1:
By introducing lateral flow as a second dimension to the upward flow through the channeled plate, the system achieves enhanced mass transfer at controlled flow rates. This cross-flow pattern prevents flow instability and eddies that would otherwise form at higher single-direction flow rates, thereby maintaining both high plating rates and uniform plating quality.
Solution Approach 2:
The patent changes the flow regime parameters by combining vertical and lateral flow components. This parameter change creates a cross-flow pattern that improves mass transfer efficiency and plating rate while preventing flow instability and eddies, thus maintaining plating uniformity even at elevated flow rates.
3Manufacturing precision
If flow directing elements are added to control electrolyte flow, then mass transfer uniformity improves, but device complexity increases
Solution Approach 1:
The channeled ionically resistive element serves multiple functions simultaneously: it provides ionic resistance, generates upward flow through its channeled structure, and when combined with lateral flow inlet, creates the cross-flow pattern. This multi-functionality reduces the need for separate flow directing elements, thereby improving mass transfer uniformity while limiting the increase in device complexity.
Solution Approach 2:
The patent merges the flow generation function with the ionic resistance function in the channeled ionically resistive element. By combining upward flow generation through the channeled structure with lateral flow inlet, the system achieves cross-flow pattern and uniform mass transfer without requiring additional separate flow directing components, thus balancing improved uniformity with controlled complexity.
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 improves plating uniformity and rate by reducing flow eddies and stagnation, achieving uniform deposition across the substrate, particularly in high aspect ratio features, and maintaining the desired shape and thickness of plated layers, thus addressing the challenges of non-uniformity and efficiency in WLP and TSV applications.
Implementation Method 1
fluid enters the cross flow manifold both upward through the channels in the channeled plate, and laterally through a cross flow side inlet
Implementation Method 2
creating a shearing force on the substrate to enhance mass transfer
Implementation Method 3
Electrochemical deposition processes are well-established in modern integrated circuit fabrication
Implementation Method 4
the ionically resistive element is adapted to provide ionic transport through the element during electroplating
Data Source
AI summary
The embodiments herein relate to methods and apparatus for electroplating one or more materials onto a substrate. In many cases the material is a metal and the substrate is a semiconductor wafer, though the embodiments are no so limited. Typically, the embodiments herein utilize a channeled plate positioned near the substrate, creating a cross flow manifold defined on the bottom by the channeled plate, on the top by the substrate, and on the sides by a cross flow confinement ring. During plating, fluid enters the cross flow manifold both upward through the channels in the channeled plate, and laterally through a cross flow side inlet positioned on one side of the cross flow confinement ring. The flow paths combine in the cross flow manifold and exit at the cross flow exit, which is positioned opposite the cross flow inlet. These combined flow paths result in improved plating uniformity.