Balancing Electrostatic Chucking Force via RF Matching Circuit
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Solution Overview
Problem
Conventional electrostatic chucking systems in plasma processing equipment face challenges in maintaining balanced electrostatic forces, leading to substrate deformation and particle generation due to unbalanced chucking forces, and arcing issues caused by center-tap cables, which reduce chamber component life and introduce contaminants.
Innovation Solution
A system and method that utilize a plasma processing chamber with an RF matching circuit, sensor, and controller to detect changes in electrical characteristics and adjust the chucking voltage of a bipolar electrostatic chuck, eliminating the need for a center-tap cable by predicting and balancing the chucking voltage based on RF matching circuit data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a center-tap cable is used to detect voltage for balancing chucking force, then the electrostatic attraction force can be maintained constant, but arcing occurs during plasma processing which reduces component life and introduces contaminants
Solution Approach 1:
The patent removes the center-tap cable from the system entirely. Instead of using a cable to detect voltage at the center-tap, the system uses the existing RF matching circuit to detect electrical characteristic changes that correlate with chucking force balance, thereby eliminating the arcing-prone cable while maintaining voltage balance capability
Solution Approach 2:
The RF matching circuit serves as an intermediary element that indirectly measures the electrical state related to chucking force balance. By detecting changes in the RF matching circuit's electrical characteristics, the system infers voltage balance without direct electrical contact at the center-tap, avoiding arcing while maintaining control
2Device complexity
If unbalanced chucking voltage is applied to electrodes, then the system operation is simpler, but substrate deformation occurs due to imbalance in electrostatic chucking force
Solution Approach 1:
The system implements feedback control by continuously monitoring electrical characteristic changes in the RF matching circuit and using this information to adjust the chucking voltage applied to each electrode. This closed-loop control maintains substrate flatness by compensating for voltage imbalances without requiring complex manual adjustment mechanisms
3Device complexity
If center-tap cable is used for voltage detection, then the system structure is simpler, but chamber components experience reduced life due to arcing
Solution Approach 1:
The center-tap cable is completely removed from the system. The patent leverages the RF matching circuit that already exists in the plasma processing system to detect electrical characteristic changes, thereby eliminating the need for additional cables and their associated arcing problems while maintaining the ability to monitor and control chucking force balance
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 reduces the risk of arcing, enhances substrate yield by maintaining uniform electrostatic forces, and improves processing quality by eliminating the need for center-tap cables, thereby reducing contamination and extending chamber component life.
Implementation Method 1
A chucking voltage is applied to one or more electrodes in the electrostatic chuck to induce oppositely polarized charges in the substrate and the electrodes, respectively. The opposite charges pull the substrate against the electrostatic chuck, thus retaining the substrate.
Implementation Method 2
a radio-frequency (RF) matching circuit coupled to the chamber
Implementation Method 3
depositing a layer of a material on the substrate by a physical vapor deposition process utilizing the plasma
Data Source
AI summary
Embodiments of the disclosure relate to methods and a system for adjusting the chucking voltage of an electrostatic chuck. In one embodiment, a system for plasma processing a substrate includes a plasma processing chamber, a radio-frequency (RF) matching circuit coupled to the chamber, a sensor and a controller. The chamber includes a chamber body having an inner volume, a bipolar electrostatic chuck disposed in the inner volume and a power supply configured to provide chucking voltage to a pair of electrodes embedded within the electrostatic chuck. When plasma is energized within the chamber by the application of RF power through an RF matching circuit, the sensor is configured to detect a change in an electrical characteristic at the RF matching circuit. The controller is coupled to the power supply and configured to adjust the chucking voltage in response to the change in the electrical characteristic detected by the sensor.