Edge Flow Element for Electroplating Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In electroplating processes for semiconductor wafers, especially for small microbumping features and through silicon via (TSV) applications, there are challenges in achieving uniform mass transfer and plating rates due to the formation of flow eddies and stagnation, leading to non-uniformity and reduced plating efficiency at smaller feature sizes.
Innovation Solution
The use of a channeled ionically resistive plate (CIRP) with an edge flow element that creates a cross-flow manifold and directs electrolyte flow near the substrate's periphery, promoting shear flow and uniform plating by combining impinging and shear flow mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electroplating flow patterns are used, then the process is simple, but mass transfer becomes non-uniform and plating rate decreases at smaller feature sizes
Solution Approach 1:
The patent applies local quality by introducing an edge flow element specifically at the periphery of the substrate to create localized shear flow in the corner region. This targeted intervention addresses the specific mass transfer deficiency at the edges without requiring complete redesign of the entire flow system, thereby improving plating uniformity with minimal added complexity.
Solution Approach 2:
The edge flow element acts as an intermediary component that mediates between the bulk electrolyte flow and the stagnant corner region. It creates a controlled shear flow that connects the main flow to the previously isolated corner area, enabling effective mass transfer without requiring direct modification of the substrate or substrate holder geometry.
2Productivity
If feature size is reduced to meet miniaturization requirements, then device density increases, but flow eddies and stagnation inhibit mass transfer rate
Solution Approach 1:
The patent introduces a new spatial dimension for flow control by positioning the edge flow element in the corner region between the substrate and substrate holder. This three-dimensional placement creates a localized flow path that addresses mass transfer limitations without requiring changes to the two-dimensional substrate surface or overall flow pattern, thereby maintaining productivity while improving uniformity.
3Productivity
If plating rate is increased to meet manufacturing requirements, then productivity improves, but mass transfer limitations cause non-uniform plating
Solution Approach 1:
The patent changes the flow dynamics parameter by introducing controlled shear flow through the edge flow element. This modifies the velocity distribution and flow patterns in the corner region, enabling higher plating rates to be achieved uniformly across the entire substrate surface without the mass transfer limitations that would otherwise cause non-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
This approach enhances plating uniformity and rate by improving mass transfer and reducing non-uniformity across the wafer surface, achieving high-quality electroplating results even at smaller feature sizes.
Implementation Method 1
The edge flow element promotes a relatively higher degree of shear flow near the edge of the substrate, where the substrate contacts the substrate holder
Implementation Method 2
controlling electrolyte hydrodynamics during electroplating
Implementation Method 3
creating a cross flow manifold defined on the bottom by the CIRP, and on the top by the substrate
Implementation Method 4
Electrochemical deposition processes are well-established in modern integrated circuit fabrication
Implementation Method 5
electroplating the metal into very thin, high-aspect ratio trenches and vias
Implementation Method 6
the 1D diffusion equilibration time constant for a purely diffusion process scales with feature depth L and the diffusion constant D
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. Also typically present is an edge flow element configured to direct electrolyte into a corner formed between the substrate and substrate holder. 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 and the edge flow element result in improved plating uniformity, especially at the periphery of the substrate.