RF Plasma Bias Waveforms for Ion Energy and Angle Control
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Solution Overview
Problem
Current plasma processing technologies face challenges in achieving precise control over edge profile, roughness, anisotropy, uniformity, and selectivity in 3D device fabrication due to limitations in RF signal waveform generation, which affect ion energy and ion angle distributions.
Innovation Solution
A method and system for plasma processing that utilize a plasma processing chamber with RF source and bipolar-DC bias signal waveforms, where the bias signal has a waveform with negative, positive, and neutral polarity durations, synchronized with RF source signals to tune the plasma environment, enabling precise control over plasma properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional RF signal waveforms are used for plasma processing, then the plasma processing system is simple to operate, but the manufacturing precision of 3D devices deteriorates due to insufficient control over ion energy and ion angle distributions
Solution Approach 1:
The patent applies dynamics by transitioning from static, continuous RF waveforms to dynamic, time-varying waveforms that change characteristics during the plasma processing cycle. The RF source waveform is modulated to different frequencies and amplitudes at different time points to dynamically control ion energy and angle distributions, enabling precise control over deposition and etching processes in 3D devices.
Solution Approach 2:
The patent implements periodic action by using cyclically varying RF waveforms that alternate between different states (e.g., high frequency/low amplitude and low frequency/high amplitude phases). This periodic modulation allows controlled alternation between ion acceleration phases and plasma maintenance phases, achieving precise control over ion bombardment characteristics while maintaining plasma stability.
2Manufacturing precision
If advanced RF signal waveforms with multiple parameters are used, then the precision and control of plasma processing is improved, but the device complexity increases
Solution Approach 1:
The patent applies parameter changes by systematically varying multiple RF waveform parameters (frequency, amplitude, duty cycle, phase) to optimize different plasma processing outcomes. Different parameter combinations are used for different process stages: higher frequencies for plasma maintenance, lower frequencies for ion acceleration, and specific amplitude ratios for controlling ion angle distributions, thereby achieving precise control over edge profile, roughness, anisotropy, and selectivity.
Solution Approach 2:
The patent implements segmentation by dividing the RF waveform into distinct time segments or phases, each with optimized parameters for specific functions. The waveform is segmented into plasma generation phases, ion acceleration phases, and relaxation phases, allowing independent optimization of each segment's parameters to achieve multiple process objectives simultaneously without requiring overly complex continuous waveforms.
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 precision and control of plasma processing, improving the fabrication of 3D devices by optimizing ion and radical distributions, leading to better edge profiles, uniformity, and selectivity in semiconductor manufacturing.
Implementation Method 1
sustaining a plasma in a plasma processing chamber
Implementation Method 2
coupling an RF source signal to the first RF electrode
Implementation Method 3
the bias signal having a bipolar DC (B-DC) waveform including a plurality of B-DC pulses, each of the B-DC pulses including: a negative bias duration during which the pulse has negative polarity, a positive bias duration during which the pulse has positive polarity
Implementation Method 4
coupling a bias signal between the first RF electrode and the second RF electrode
Data Source
AI summary
A method for plasma processing includes: sustaining a plasma in a plasma processing chamber, the plasma processing chamber including a first radio frequency (RF) electrode and a second RF electrode, where sustaining the plasma includes: coupling an RF source signal to the first RF electrode; and coupling a bias signal between the first RF electrode and the second RF electrode, the bias signal having a bipolar DC (B-DC) waveform including a plurality of B-DC pulses, each of the B-DC pulses including: a negative bias duration during which the pulse has negative polarity relative to a reference potential, a positive bias duration during which the pulse has positive polarity relative to the reference potential, and a neutral bias duration during which the pulse has neutral polarity relative to the reference potential.