Electrostatic Chuck Attraction Using N-Phase AC Bias
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Solution Overview
Problem
Existing methods for attracting substrates and edge rings in plasma processing apparatuses experience a reduction in attractive force due to charge movement and temperature changes, leading to instability during prolonged processing.
Innovation Solution
Applying n-phase alternating current (AC) voltages to electrodes in the electrostatic chuck, where each phase has a different phase and is based on the self-bias voltage of the object, to maintain consistent attractive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If DC voltage is applied to the electrostatic chuck to attract the substrate, then the substrate is firmly attached to the mounting table, but the attractive force decreases over time due to charge movement and temperature changes
Solution Approach 1:
The patent applies AC voltage instead of DC voltage to the electrostatic chuck. The AC voltage periodically reverses polarity, preventing charge accumulation and maintaining stable attractive force throughout the processing period. This periodic action eliminates the gradual force reduction observed with DC voltage while keeping the substrate firmly attached.
Solution Approach 2:
The patent changes the voltage parameter from DC to AC, specifically using n-phase AC voltages with controlled phase differences. This parameter change transforms the electrical characteristics applied to the electrostatic chuck, enabling stable attraction force by preventing charge buildup and compensating for temperature-induced variations during plasma processing.
2Stability of the object's composition
If n-phase AC voltages are applied to maintain stable attractive force, then the attractive force remains consistent, but the system complexity increases due to phase voltage control requirements
Solution Approach 1:
The patent divides the single voltage control into n-phase AC voltages with different phase angles. Each phase is controlled independently but coordinates with others to produce a combined effect that stabilizes the attractive force. This segmentation allows the system to maintain stability while using standard AC voltage sources rather than requiring complex variable voltage control.
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
Prevents reduction in attractive force over time, ensuring stable attachment of substrates and edge rings during prolonged plasma processing, particularly in complex processes like 3D NAND device fabrication.
Implementation Method 1
a mounting table provided with an electrostatic chuck including electrodes
Implementation Method 2
n-phase alternating current (AC) voltages (n≥2) are applied to the electrodes. Each phase voltage of the n-phase AC voltages has a phase different from each other
Data Source
AI summary
A method of attracting an object to a mounting table is provided. The object is a substrate, an edge ring, or a combination of the substrate and the edge ring. The mounting table is provided with an electrostatic chuck including electrodes. After the object is placed on the electrostatic chuck, n-phase alternating current (AC) voltages (n≥2) are applied to the electrodes. Each phase voltage of the n-phase AC voltages has a phase different from each other, and the phase voltage of the n-phase AC voltages is applied based on a self-bias voltage of the object.