Split Magnet Ring for Uniform Tantalum Deposition
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Solution Overview
Problem
Conventional sputter reactors face challenges in achieving uniform deposition and etching of refractory metals like tantalum within high aspect-ratio holes, particularly due to non-uniform magnetic fields that lead to uneven plasma distribution and resputtering issues.
Innovation Solution
A split magnet ring assembly is positioned around the processing area of a plasma sputter reactor, comprising two magnet rings of the same polarity separated by non-magnetic material, which flattens the magnetic field and reduces plasma diffusion to the chamber sidewall, enhancing uniformity and reducing resputtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional single magnet ring is used in the sputter reactor, then the magnetic field provides plasma confinement, but the magnetic field is non-uniform causing uneven plasma distribution and resputtering issues
Solution Approach 1:
The single magnet ring is divided into two separate magnet rings positioned at different axial locations within the chamber. This segmentation allows each ring to contribute to different regions of the magnetic field, creating a more uniform overall field distribution that improves plasma confinement and reduces resputtering while maintaining ease of operation.
2Manufacturing precision
If the magnetic field is strengthened to improve plasma confinement, then deposition uniformity improves, but plasma diffusion to chamber sidewall increases causing resputtering
Solution Approach 1:
The two magnet rings are positioned at different axial locations to create locally optimized magnetic field distributions. The first ring addresses plasma confinement in one region while the second ring addresses confinement in another region, collectively achieving uniform deposition without excessive plasma diffusion to sidewalls that would cause resputtering.
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 split magnet ring configuration improves radial uniformity and reduces resputtering, resulting in more uniform deposition and etching of refractory metals, such as tantalum, by maintaining a stronger average magnetic field density and minimizing plasma focusing towards the center.
Implementation Method 1
A split magnet ring assembly is positioned around the processing area of a plasma sputter reactor, comprising two magnet rings of the same polarity separated by non-magnetic material, which flattens the magnetic field and reduces plasma diffusion to the chamber sidewall
Implementation Method 2
The split magnet ring configuration improves radial uniformity and reduces resputtering, resulting in more uniform deposition and etching of refractory metals, such as tantalum, by maintaining a stronger average magnetic field density
Implementation Method 3
Sputtering, alternatively called physical vapor deposition (PVD), is commonly used in depositing layers of metals and related materials in the fabrication of semiconductor integrated circuits
Data Source
AI summary
A split magnet ring, particularly useful in a magnetron plasma reactor sputter depositing tantalum or tungsten or other barrier metal into a via and also resputter etching the deposited material from the bottom of the via onto the via sidewalls. The magnet ring includes two annular magnet rings composed of the same axial polarity separated by a non-magnetic spacing of at least the axial length of one magnet and associated poles. A small unbalanced magnetrons rotates about the back of the target having an outer pole of the same polarity as the ring magnets surrounding a weaker inner pole of the opposite pole.