Synchronous RF Power Modulation for Plasma Stability
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Solution Overview
Problem
Current plasma processing techniques face challenges in maintaining stability and reproducibility due to impedance changes and reflection waves caused by modulating radio frequency power amplitude at regular intervals, leading to charging damage and non-uniformity issues during semiconductor and FPD manufacturing.
Innovation Solution
A plasma processing apparatus and method that modulates the amplitude and frequency of radio frequency power synchronously to control ion energy and plasma impedance, minimizing impedance changes and reflection waves, using a configuration with a vacuum chamber, electrodes, and matching units to ensure stability and reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the amplitude of radio frequency power is modulated at regular intervals to prevent charging damage, then charging damage is reduced, but impedance changes and reflection waves occur causing instability and reproducibility issues
Solution Approach 1:
The patent applies periodic action by modulating the amplitude of radio frequency power at regular intervals (pulse modulation) to prevent charging damage to the gate oxide film. The modulation switches between high and low levels with a variable duty cycle, creating periodic plasma generation and cessation that controls ion bombardment and charge accumulation on the substrate surface.
Solution Approach 2:
The patent changes the amplitude parameter of radio frequency power through pulse modulation to control plasma density and ion energy. By varying the duty cycle and modulation frequency, the system adjusts the average power delivered to the plasma while maintaining instantaneous high power levels for effective etching when plasma is present.
2Object-affected harmful factors
If the amplitude of radio frequency power is modulated at regular intervals, then charging damage is reduced, but automatic matching function deteriorates causing changes in plasma generation characteristics
Solution Approach 1:
The system uses periodic amplitude modulation of radio frequency power to create controlled plasma on/off cycles. This periodic action allows the plasma impedance to adapt to the modulation frequency, and by optimizing the duty cycle and frequency, the system maintains sufficient plasma uniformity across the substrate while preventing charging damage during the off periods.
3Object-affected harmful factors
If the amplitude of radio frequency power is modulated at regular intervals, then charging damage is reduced, but reflection wave causes overheating and breakdown of radio frequency power supply
Solution Approach 1:
The periodic modulation creates predictable impedance variations that can be managed by the matching network. By synchronizing the modulation frequency with the plasma response time and using appropriate duty cycles, the system minimizes reflection waves while maintaining the protective off-periods that prevent charging damage.
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
The synchronous modulation of radio frequency power amplitude and frequency stabilizes plasma processing, reducing charging damage and non-uniformity, thereby enhancing the stability and reproducibility of the process while protecting the radio frequency power supply.
Implementation Method 1
a plasma excitation unit for generating a plasma by exciting the processing gas in the processing chamber
Implementation Method 2
a first radio frequency power frequency modulation unit for modulating a frequency of the first radio frequency power in substantially synchronously with the amplitude modulation of the first radio frequency power
Implementation Method 3
a first radio frequency power supply unit for supplying a first radio frequency power to the first electrode to attract ions in the plasma to the substrate
Data Source
AI summary
A plasma processing apparatus includes a vacuum evacuable processing chamber; a first electrode for supporting a substrate to be processed in the processing chamber; a processing gas supply unit for supplying a processing gas into a processing space; a plasma excitation unit for generating a plasma by exciting the processing gas in the processing chamber; a first radio frequency power supply unit for supplying a first radio frequency power to the first electrode to attract ions in the plasma to the substrate; and a first radio frequency power amplitude modulation unit for modulating an amplitude of the first radio frequency power at a predetermined interval. The plasma processing apparatus further includes a first radio frequency power frequency modulation unit for modulating a frequency of the first radio frequency power in substantially synchronously with the amplitude modulation of the first radio frequency power.