Carrier Wave Group Plasma Processing for Stable Low-Pressure Ion Control
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Solution Overview
Problem
Conventional plasma processing apparatuses face challenges in stably maintaining plasma at low pressure and low plasma density, with difficulty in accurately controlling ion energy distribution due to fluctuations in high frequency power and electric fields.
Innovation Solution
A plasma processing apparatus that generates a carrier wave group with alternating first and second peaks in the time domain, allowing for controlled ion energy distribution and stable plasma maintenance by alternately generating plasma ignition and maintenance electric fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high frequency power is increased to maintain plasma under low pressure environment, then plasma maintenance is improved, but plasma density becomes excessively increased
Solution Approach 1:
The patent applies periodic action by using a pulsed power supply that alternates between a first high frequency power for plasma generation and a second high frequency power for plasma maintenance. This periodic switching allows the system to achieve stable plasma maintenance at low pressure while controlling plasma density by using lower power during maintenance phases, thus resolving the contradiction between reliable plasma maintenance and excessive plasma density increase.
2Quantity of substance
If high frequency power is decreased to suppress excessive plasma density increase, then plasma density control is improved, but electric field becomes insufficient to maintain plasma
Solution Approach 1:
The pulsed power supply implements periodic action by switching between two distinct power levels: a first high frequency power sufficient for plasma generation and ionization, and a second reduced high frequency power for plasma maintenance. This periodic modulation allows the system to suppress excessive plasma density during maintenance while ensuring sufficient electric field strength during generation phases, thereby resolving the contradiction between plasma density control and plasma maintenance stability.
3Use of energy by moving object
If low frequency is used to obtain high ion energy, then ion energy is improved, but ion energy distribution becomes broader and harder to control
Solution Approach 1:
The patent applies parameter changes by utilizing multiple high frequency power levels instead of a single low frequency. By switching between a first high frequency power (for plasma generation) and a second high frequency power (for plasma maintenance), the system achieves high ion energy while maintaining narrow ion energy distribution. This approach resolves the contradiction by changing the frequency parameter from low to high while using pulsed modulation to control energy distribution precision.
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
Enables stable plasma maintenance at low pressure and low plasma density while improving controllability of ion energy distribution, preventing excessive plasma density increases and ensuring sufficient electric fields for plasma sustenance.
Implementation Method 1
The plasma generation unit is configured to generate a plasma in the processing chamber by using the carrier wave group
Implementation Method 2
when the high frequency power is increased, an electric field in the processing chamber is increased. Accordingly, ionization of the plasma is accelerated
Data Source
AI summary
A plasma processing apparatus includes a processing chamber, a carrier wave group generation unit and a plasma generation unit. The carrier wave group generation unit is configured to generate a carrier wave group including a plurality of carrier waves having different frequencies in a frequency domain. The carrier wave group is represented by an amplitude waveform in which a first peak and a second peak of which absolute value is smaller than an absolute value of the first peak alternately appear in a time domain. The plasma generation unit is configured to generate a plasma in the processing chamber by using the carrier wave group.