Electrostatic Chuck With Three-Phase AC Voltage
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Solution Overview
Problem
Existing electrostatic chucks in plasma processing apparatuses face challenges in maintaining consistent adsorptive force and preventing residual electric charges, which can lead to decreased adsorption efficiency and contamination issues.
Innovation Solution
Applying three AC voltages with different phases to three electrodes of the electrostatic chuck, ensuring continuous potential differences and alternating electric field intensities to maintain adsorptive force while minimizing residual charges, and using a depressurization pump to attract and position the focus ring without applying voltages under atmospheric pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If DC voltage is applied to the electrode of the electrostatic chuck, then the target object is adsorbed on the electrostatic chuck, but electric charges remain on the surface of the electrostatic chuck after voltage application is stopped
Solution Approach 1:
The patent applies AC voltage instead of DC voltage to the electrostatic chuck electrode. The AC voltage periodically reverses polarity, creating alternating positive and negative cycles that prevent charge accumulation. This periodic action allows the electrostatic chuck to maintain adsorptive force during the positive cycle while the negative cycle dissipates residual charges, thus resolving the contradiction between maintaining adsorption and preventing charge buildup.
Solution Approach 2:
The patent changes the voltage parameter from DC (direct current) to AC (alternating current). This parameter change transforms the electrical characteristics from unidirectional to bidirectional, enabling the system to maintain adsorptive force when needed while automatically eliminating residual charges through the alternating polarity cycles, thereby solving the contradiction between sustained adsorption and charge prevention.
2Ease of manufacture
If the surface of the electrostatic chuck is modified by process products, then electrification becomes easier, but adsorptive force decreases due to abnormal electrification
Solution Approach 1:
By using AC voltage with alternating polarity, the patent prevents abnormal electrification that would occur with DC voltage on modified surfaces. The periodic reversal of voltage polarity prevents charge accumulation and abnormal electrification effects, allowing the chuck to maintain both ease of electrification on modified surfaces and sustained adsorptive force throughout the processing cycle.
Solution Approach 2:
The AC voltage application ensures continuous useful action by maintaining adsorptive force throughout the entire voltage cycle. Unlike DC voltage which would cause abnormal electrification and force degradation over time, the continuous alternating action of AC voltage sustains proper electrification and adsorptive force continuously, preventing the degradation that occurs with modified surfaces.
3Reliability
If three AC voltages with different phases are applied to three electrodes, then residual electric charges are suppressed, but device complexity increases
Solution Approach 1:
The patent divides the single electrode into three separate electrodes, each connected to an AC power supply with a different phase. This segmentation allows each electrode to independently contribute to charge suppression through its phase-differentiated AC voltage, collectively achieving superior residual charge suppression while distributing the complexity across multiple simpler components rather than one complex system.
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 maintains a continuous adsorptive force, suppresses residual electric charges on the electrostatic chuck, and prevents contamination and position deviation of the focus ring during processing, enhancing the controllability and efficiency of the plasma processing apparatus.
Implementation Method 1
when the DC voltage is applied to the electrode, a surface of the electrostatic chuck is electrified. Furthermore, since a target object is electrically grounded, a surface of the target object facing the electrostatic chuck is electrified with polarities opposite to those of the surface of the electrostatic chuck. Thus, a potential difference between the surface of the electrostatic chuck and the target object is made, so that the target object is adsorbed on the electrostatic chuck.
Implementation Method 2
Applying three AC voltages with different phases to three electrodes of the electrostatic chuck, ensuring continuous potential differences and alternating electric field intensities to maintain adsorptive force while minimizing residual charges
Data Source
AI summary
A plasma processing apparatus of processing a processing target object within a depressurized space is provided. The plasma processing apparatus includes a processing vessel that partitions a depressurizable space; a mounting table, provided within the processing vessel, having an electrostatic chuck which is for a focus ring and has three electrodes; a power supply configured to apply three AC voltages having different phases to the three electrodes, respectively, to adsorb a target object on the electrostatic chuck.