Variable Impedance Matcher for Plasma Processing
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Solution Overview
Problem
Current plasma processing apparatuses face inefficiencies in plasma generation due to impedance mismatching, leading to variations in ion energy delivery to substrates, which affects processing quality and efficiency.
Innovation Solution
The apparatus incorporates a second matcher with a variable impedance matching circuit and controller to reduce reflections from the load during specific periods of the radio-frequency power cycle, optimizing ion energy delivery by designating partial periods for high and low energy ion generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed impedance matching circuit is used in the second matcher, then the apparatus structure is simple, but plasma generation efficiency varies due to impedance mismatching throughout the RF cycle
Solution Approach 1:
The patent applies the dynamics principle by making the impedance matching circuit variable rather than fixed. The second matcher includes a variable impedance matching circuit that can dynamically adjust its impedance characteristics during the RF power cycle. This is achieved through components such as variable capacitors or switches that allow the matching circuit to change its impedance state, thereby maintaining optimal plasma generation efficiency throughout different phases of the RF cycle while managing the complexity through controlled variability.
Solution Approach 2:
The patent implements periodic action by designing the impedance matching circuit to vary its impedance characteristics in synchronization with the RF power cycle. The controller adjusts the matching circuit's impedance periodically, creating high impedance during ion acceleration phases and low impedance during plasma generation phases. This periodic adjustment ensures optimal plasma generation efficiency at different stages of the RF cycle, directly addressing the productivity improvement while managing device complexity through rhythmic, predictable changes.
2Manufacturing precision
If impedance matching is maintained throughout the entire RF cycle, then plasma generation is efficient, but ion energy delivery to substrate varies affecting processing quality
Solution Approach 1:
The patent applies segmentation by dividing the RF power cycle into distinct phases and applying different impedance matching strategies to each phase. The controller segments the cycle into periods requiring high ion energy (where high impedance is applied) and periods requiring efficient plasma generation (where low impedance is applied). This segmentation allows independent optimization of processing quality during ion acceleration and productivity during plasma generation, resolving the contradiction between the two objectives.
Solution Approach 2:
The patent implements local quality by applying different impedance characteristics to different time periods within the RF cycle rather than using a uniform impedance setting. During specific portions of the cycle when ion acceleration is critical, the matching circuit provides high impedance to ensure precise ion energy delivery for processing quality. During other portions when plasma generation is prioritized, the circuit switches to low impedance for efficiency. This localized optimization of impedance characteristics resolves the contradiction between processing quality and productivity.
3Manufacturing precision
If variable impedance matching circuit is used in the second matcher, then ion energy delivery is optimized, but the apparatus complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the impedance parameters of the matching circuit dynamically rather than using a fixed configuration. The variable impedance matching circuit changes its electrical parameters (impedance magnitude and phase) in response to controller signals, allowing optimization of ion energy delivery precision. This parameter variability is achieved through components like variable capacitors, inductors, or switchable impedance networks, which provide the necessary flexibility while maintaining a relatively compact and manageable apparatus configuration.
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 plasma generation efficiency by ensuring desired ion energies are efficiently supplied to the substrate, improving processing outcomes and maintaining a relatively simple and cost-effective apparatus configuration.
Implementation Method 1
The controller is configured to set an impedance of the matching circuit such that a reflection from the load of the second radio-frequency power supply is reduced in a partial period designated within each cycle of the first radio-frequency power
Implementation Method 2
The second radio-frequency power supply is configured to supply second radio-frequency power for plasma generation
Data Source
AI summary
In a plasma processing apparatus according to an embodiment, a first radio-frequency power supply is connected to a lower electrode of a substrate support provided within a chamber via a first matcher. The first radio-frequency power supply supplies first radio-frequency power for bias to the lower electrode. The second radio-frequency power supply is connected to a load via a second matcher. The second radio-frequency power supply supplies second radio-frequency power for plasma generation. A controller of the second matcher sets an impedance of a matching circuit of the second matcher such that a reflection from the load of the second radio-frequency power supply is reduced in a designated partial period within each cycle of the first radio-frequency power.