Subtractive Metal Patterning for High-Aspect-Ratio Interconnects
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Solution Overview
Problem
Conventional subtractive metal patterning techniques are inadequate for manufacturing metal features with small feature sizes and high aspect ratios required for next-generation electronic devices, as they suffer from issues like pinch-off voiding and increased resistance, and existing gapfill techniques are not reliable for high aspect ratio trenches.
Innovation Solution
The development of metal etch tools with electrodes made of the same material as the sample, which allows for reliable and cost-effective subtractive patterning of metals like copper and platinum, enabling features with pitches lower than conventional tools and aspect ratios greater than those achievable by existing methods, by using a chamber with specific configurations and control systems to manage plasma and ion energies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional subtractive metal patterning techniques are used, then manufacturing process is simple, but feature size and aspect ratio are insufficient for next-generation devices
Solution Approach 1:
The etch tool is segmented into distinct functional zones: a source region for generating metal ions, a transport region with controlled plasma environment, and a processing region where patterning occurs. This segmentation allows independent optimization of each zone to achieve high aspect ratio etching while maintaining process control
Solution Approach 2:
A controlled plasma environment acts as an intermediary medium between the metal ion source and the substrate. The plasma provides both the ion flux for etching and the chemical environment necessary for anisotropic profile control, enabling precise feature formation at high aspect ratios
2Reliability
If existing gapfill techniques are used for high aspect ratio trenches, then some features can be filled, but pinch-off voiding and increased resistance occur
Solution Approach 1:
The mechanical pressure-driven gapfill process is replaced with a plasma-based transport mechanism. Metal ions are accelerated through controlled electric and magnetic fields, enabling deposition in high aspect ratio trenches without requiring high pressure that causes pinch-off voiding
Solution Approach 2:
The deposition parameters are fundamentally changed from pressure-driven atomic layer deposition to plasma-enhanced ion beam deposition. This allows control of deposition rate and profile by adjusting plasma power, ion energy, and gas composition rather than relying on pressure gradients
3Manufacturing precision
If conventional etch tools are used, then tool structure is simple, but pitch and aspect ratio capabilities are insufficient
Solution Approach 1:
The source region is nested within the processing chamber, with the substrate positioned to receive ions from the source through a controlled path. This nested configuration allows the source to be integrated into the chamber structure, providing high ion flux without requiring a completely separate external ion source system
Solution Approach 2:
The etch process transitions from conventional planar ion bombardment to a three-dimensional ion transport path with controlled angular distribution. Ions are directed along specific trajectories through magnetic field confinement and electrostatic focusing, enabling anisotropic etching at high aspect ratios
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
These tools enable the formation of metal features with improved aspect ratios and reduced resistance, enhancing the performance of interconnects in integrated circuits by maximizing metal volume and reducing RC delay, while being suitable for high-volume manufacturing.
Implementation Method 1
controlling the metal etch tool to etch the metal of the sample
Implementation Method 2
controlling the metal etch tool to etch the metal of the sample
Data Source
AI summary
Disclosed herein are tools and methods for subtractively patterning metals. These tools and methods may permit the subtractive patterning of metal (e.g., copper, platinum, etc.) at pitches lower than those achievable by conventional etch tools and/or with aspect ratios greater than those achievable by conventional etch tools. The tools and methods disclosed herein may be cost-effective and appropriate for high-volume manufacturing, in contrast to conventional etch tools.