Pulsed Plasma Bias Waveforms for Ion Energy Control in Etching
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Solution Overview
Problem
Current plasma-assisted etching processes, particularly at advanced technology nodes like 2 nanometers, face challenges in controlling ion energy and achieving consistent results due to limitations in traditional RF generator and RF biasing methods.
Innovation Solution
The method involves generating a pulsed radio frequency (RF) waveform and a pulsed voltage (PV) waveform, where the delivery of the PV waveform overlaps with the RF waveform, allowing for controlled plasma processing and improved ion energy management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional RF generator and RF biasing methods are used, then plasma is formed and ions are accelerated towards the substrate, but ion energy control is insufficient and process results are inconsistent
Solution Approach 1:
The patent applies periodic action by using pulsed RF waveforms instead of continuous sinusoidal RF. The RF generator delivers RF power in controlled pulses with specific duty cycles, frequencies, and pulse widths, enabling precise temporal control over plasma generation and ion acceleration. This periodic modulation allows independent control of ion energy and flux, resolving the contradiction between manufacturing precision and process reliability.
Solution Approach 2:
The patent implements dynamics by making the RF biasing parameters adjustable and time-dependent. The system dynamically modifies RF pulse characteristics (amplitude, width, frequency, duty cycle) during processing to optimize ion energy control. This dynamic control capability enables adaptation to different process requirements, achieving both precise ion energy control and consistent results across varying conditions.
2Adaptability or versatility
If sinusoidal RF waveform is used to excite the plasma, then plasma is formed, but the sinusoidal shape limits ability to adjust ion energy during processing
Solution Approach 1:
The patent applies parameter changes by transitioning from fixed sinusoidal RF waveforms to programmable pulsed RF waveforms with multiple controllable parameters. The system independently adjusts pulse amplitude, pulse width, frequency, and duty cycle to precisely control plasma sheath properties and ion energy. This multi-parameter control provides the adaptability needed for ion energy adjustment while maintaining manufacturing precision through optimized waveform characteristics.
3Manufacturing precision
If RF biasing methods are used, then plasma processing is performed, but there is inability to desirably control plasma sheath properties for smaller feature sizes
Solution Approach 1:
The patent uses periodic action with pulsed RF waveforms to achieve precise control over plasma sheath properties. By modulating the RF power delivery in pulses with optimized duty cycles and frequencies, the system creates controlled plasma sheath collapse and ion bombardment events. This periodic control enables precise feature size control while providing the flexibility needed for advanced patterning processes.
Solution Approach 2:
The patent implements dynamic control of plasma sheath properties through time-dependent RF pulse parameters. The system dynamically adjusts pulse characteristics during processing to optimize sheath control for different feature sizes and aspect ratios. This dynamic adaptability enables precise control of plasma interactions with the substrate, achieving the manufacturing precision required for smaller features while maintaining process flexibility.
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 control over plasma properties, leading to improved etch results, such as better aspect-ratio control and profile uniformity, which are critical for forming high aspect ratio features in semiconductor devices.
Implementation Method 1
ions are accelerated from the plasma towards the substrate across a plasma sheath
Implementation Method 2
a plasma is formed in a processing chamber and ions from the plasma are accelerated
Data Source
AI summary
Embodiments of the disclosure include apparatus (e.g., plasma processing systems) and methods for the plasma processing of a substrate in a processing chamber. Some embodiments are directed to a method for waveform generation, which generally includes delivering a radio frequency (RF) waveform at a frequency for a first period of time using a RF generator and then halting the delivery of the RF waveform for a second period of time, and delivering a pulsed voltage waveform at a first voltage for at least a portion of a third period of time using a pulser, wherein the delivery of the pulsed voltage waveform overlaps with the delivery of the RF waveform during a portion of the second period of time.