Resonant Circuit Tuning for Expanded CCP Plasma Region
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Solution Overview
Problem
Dual-frequency CCP plasma processing apparatuses face challenges in expanding the plasma formation region to the vicinity of the processing substrate, limiting the increase in processing speed.
Innovation Solution
Incorporating a resonant circuit that allows high-frequency current at the second frequency to pass through, reducing impedance between the counter electrode and the substrate-supporting stage, and adjusting the resonant frequency to match the second frequency to enhance plasma expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If dual-frequency CCP plasma processing is applied, then plasma generation capability is improved, but plasma formation region expansion to substrate vicinity is limited
Solution Approach 1:
The patent introduces a resonant circuit as an intermediary component between the upper electrode and ground. This resonant circuit acts as a mediator that enables efficient energy transfer and plasma current flow, allowing the plasma formation region to expand toward the substrate without compromising plasma generation capability. The resonant circuit facilitates the coupling between the second high-frequency voltage and the plasma, solving the contradiction by providing an intermediate pathway for energy transmission.
Solution Approach 2:
The patent utilizes parameter changes in the resonant circuit, specifically adjusting the resonant frequency to match the second high-frequency voltage frequency. By changing the electrical parameters (inductance and capacitance) of the resonant circuit, the system optimizes plasma current flow and expands the plasma formation region. This parameter adjustment allows the system to maintain high plasma generation capability while extending the plasma region to the substrate vicinity.
2Productivity
If plasma formation region is expanded to substrate vicinity, then processing speed increases, but impedance of plasma current increases
Solution Approach 1:
The resonant circuit serves as an intermediary that bridges the impedance mismatch between the upper electrode and the substrate vicinity. By introducing this intermediate component with tuned resonant properties, the system can expand the plasma formation region to increase processing speed while the resonant circuit simultaneously provides a low-impedance pathway for plasma current flow, thus maintaining current reliability.
Solution Approach 2:
The resonant circuit exploits electromagnetic resonance (analogous to mechanical vibration principles) at the second high-frequency voltage frequency. This resonance phenomenon creates enhanced current flow conditions that allow plasma to expand to the substrate vicinity for increased processing speed, while the resonant condition itself ensures low impedance by matching the natural oscillation frequency of the circuit, thereby maintaining current reliability.
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 expanded plasma formation region leads to increased processing speed, as demonstrated by improved etching rates and efficient use of high-frequency voltage.
Implementation Method 1
The resonant circuit allows high-frequency current at the second frequency from the counter electrode to pass therethrough. Since this plasma processing apparatus includes the resonant circuit that allows the high-frequency current at the second frequency from the counter electrode to pass therethrough between the power supply line and a ground potential, impedance of plasma current flowing to the stage from the counter electrode decreases.
Implementation Method 2
Capacitive coupling plasma vacuum processing apparatuses of vacuum processing apparatuses such as etching apparatuses are known. For example, Patent Literature 1 has disclosed an apparatus that performs plasma processing by applying a first high-frequency voltage to a lower electrode supporting a processing substrate and applying a second high-frequency voltage to an upper electrode with a gas-introducing mechanism to generate a capacitive coupling plasma.
Data Source
AI summary
[Object] To provide a plasma processing apparatus capable of expanding an formation region of plasma generated on an upper electrode side to increase the processing speed and a control method therefor.[Solving Means] A plasma processing apparatus according to an embodiment of the present invention includes a vacuum chamber, a substrate-supporting stage, a counter electrode, and a resonant circuit. The substrate-supporting stage is disposed inside the vacuum chamber and is connected to a first high-frequency power supply circuit that supplies a high-frequency power at a first frequency. The counter electrode is disposed in opposite to the stage and is connected to a second high-frequency power supply circuit that supplies a high-frequency power at a second frequency. The resonant circuit allows high-frequency current at the second frequency from the counter electrode to pass therethrough.