Plasma Etching Rate Uniformity via Dynamic Electromagnet Control
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Solution Overview
Problem
Existing plasma etching methods using capacitively coupled plasma processing apparatuses face limitations in controlling the distribution of etching rates across the diameter of a workpiece, often resulting in fixed magnetic fields and localized peaks due to electron confinement, which reduces controllability and uniformity of the etching process.
Innovation Solution
The method involves controlling the current supplied to a plurality of electromagnets arranged coaxially or in concentric circles around the central axis of a plasma processing apparatus, allowing for dynamic adjustment of the magnetic field and etching rate distribution across the workpiece during plasma generation, enabling the achievement of varied and uniform etching rates by alternating or sequencing current settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed current is supplied to the electromagnets, then the apparatus structure is simple and easy to operate, but the etching rate distribution uniformity deteriorates due to localized peaks from electron confinement
Solution Approach 1:
The single electromagnet is divided into multiple electromagnets arranged in the radial direction. Each electromagnet can be controlled independently, allowing the etching rate to be adjusted at different radial positions. This segmentation enables precise control over the etching rate distribution, eliminating localized peaks while maintaining operational simplicity through standardized modular components.
Solution Approach 2:
The system transitions from a fixed current supply to a dynamic current control system where the current to each electromagnet can be adjusted independently. This allows real-time optimization of the etching rate distribution across the workpiece surface, adapting to different processing requirements while maintaining ease of operation through automated control.
2Device complexity
If the magnetic field is fixed, then the device complexity is reduced, but the controllability of etching rate distribution deteriorates
Solution Approach 1:
The magnetic field generation system is segmented into multiple independently controllable electromagnets. This allows the magnetic field distribution to be optimized for different etching requirements without increasing overall device complexity, as each module uses standard electromagnet design. The segmented approach provides versatile control over etching rate distribution while maintaining manageable system complexity.
Solution Approach 2:
The system enables independent adjustment of current parameters for each electromagnet, allowing dynamic optimization of the magnetic field strength and distribution. This parameter control provides high adaptability for different etching scenarios while keeping the device structure relatively simple, as it involves only electrical parameter adjustments rather than mechanical reconfigurations.
3Device complexity
If a single electromagnet is used, then the device complexity is low, but the ability to control diametric distribution of etching rate deteriorates
Solution Approach 1:
The single electromagnet is replaced with multiple electromagnets arranged radially, with each electromagnet responsible for a specific radial zone. This segmentation provides direct control over the diametric distribution of etching rates, allowing independent optimization of different regions of the workpiece while maintaining low device complexity through modular, standardized electromagnet designs.
Solution Approach 2:
Each electromagnet is optimized to provide the appropriate magnetic field strength for its specific radial position, creating local quality variations that result in uniform overall etching. This allows precise control over the diametric distribution of etching rates, with each region receiving tailored magnetic field conditions appropriate to its position, while the overall device remains relatively simple.
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 the controllability and uniformity of the etching rate distribution across the workpiece, reducing variations and achieving a more consistent etching process compared to fixed current settings, as demonstrated in test examples and simulations.
Implementation Method 1
The plurality of electromagnets are formed of a plurality of coils provided coaxially around a central axis passing through the center of placing table in the vertical direction. The plurality of electromagnets are used to adjust a diametric distribution of the density of the plasma generated within the processing container
Implementation Method 2
a processing gas is supplied into the processing container from the gas supply unit, and the processing gas is excited by a high frequency electric field formed between the upper electrode and the lower electrode. Accordingly, plasma is generated
Data Source
AI summary
Disclosed is a plasma etching method which is performed using a plasma processing apparatus that is a capacitively coupled plasma processing apparatus, and includes: a processing container; a gas supply unit that supply an etching processing gas into the processing container; a placing table including a lower electrode; an upper electrode provided above the placing table; and a plurality of electromagnets including a plurality of coils, or a plurality of electromagnets each including a coil, on the upper electrode. The plasma etching method includes generating plasma of the processing gas to perform a plasma etching on a single film of a workpiece placed on the placing table; and controlling a current supplied to the plurality of electromagnet to change a distribution of an etching rate of the single film in the diametric direction with respect to the central axis during the generating of the plasma of the processing gas.