Magnetic Ring X-Point Layout for Edge Etch Uniformity
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Solution Overview
Problem
Plasma processing technologies face challenges in achieving accurate, precise, and uniform patterning of features at atomic scale dimensions, particularly at the edge of substrates, due to non-uniform distribution of plasma species, leading to variations in etch rate and profile control.
Innovation Solution
The implementation of an additional magnetic field with a ring X point, generated by a set of magnets, to locally neutralize the magnetic field near the substrate edge, enhancing plasma density and uniformity, using a plasma processing system with a focus ring and controlled gas delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma processing is used without additional magnetic field control, then the system is simpler, but etch uniformity across the substrate deteriorates due to non-uniform plasma species distribution
Solution Approach 1:
The patent applies local quality by creating a non-uniform magnetic field configuration with a ring X-point that concentrates plasma species at specific radial positions. The magnetic field strength varies spatially, with the X-point located at a specific radius from the substrate center, creating locally enhanced plasma density and ion flux at the ring position while maintaining different conditions at other locations. This localized magnetic field modification improves etch uniformity by compensating for edge effects without requiring uniform field enhancement across the entire substrate.
Solution Approach 2:
The patent changes magnetic field parameters by introducing an azimuthal magnetic field component through coil structures positioned above and below the substrate. The field configuration is controlled by adjusting current magnitudes and directions in the coils, creating a specific field topology with an X-point at a controllable radial position. This parameter change in magnetic field structure fundamentally alters plasma species distribution and transport, improving etch uniformity without requiring changes to the basic plasma generation process.
2Quantity of substance
If magnetic field is enhanced uniformly across the substrate, then plasma density increases, but edge-specific plasma uniformity deteriorates due to excessive confinement
Solution Approach 1:
The ring X-point configuration creates a localized region of enhanced plasma density and ion flux at a specific radial position, rather than uniform enhancement across the entire substrate. The magnetic field topology with the X-point at a controlled radius from the center creates a ring-shaped region of concentrated plasma species, providing locally enhanced etching at edge regions while maintaining appropriate plasma conditions at other locations. This resolves the contradiction by applying density enhancement only where needed for edge 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 improves etch uniformity and rate across the substrate, particularly at the edge, by enhancing local plasma density and ion/radical fluxes, resulting in consistent plasma processing performance.
Implementation Method 1
a RF power source configured to generate a plasma in the plasma processing chamber
Implementation Method 2
a first magnet disposed above the substrate holder, the first magnet configured to apply an azimuthally symmetric magnetic field in the plasma processing chamber
Implementation Method 3
a second magnet disposed below the substrate holder, the second magnet configured to modify the azimuthally symmetric magnetic field and create a ring X point where the azimuthally symmetric magnetic field is locally neutralized
Implementation Method 4
exposing the substrate to the plasma and etching the underlying layer selectively to the hard mask layer
Data Source
AI summary
A plasma etching system that includes a plasma processing chamber, a substrate holder disposed in the plasma processing chamber, a RF power source configured to generate a plasma in the plasma processing chamber, a first magnet disposed above the substrate holder, the first magnet configured to apply, in the plasma processing chamber, an azimuthally symmetric magnetic field that is independent from a magnetic field generated by the RF power source, and a second magnet disposed below the substrate holder and configured to modify the azimuthally symmetric magnetic field and create a ring X point between the first magnet and the second magnet, where positions of the first magnet and the second magnet are arranged such that the ring X point is located nearer to an edge of the substrate holder than a center of the substrate holder.