Electrostatic Chuck Grounding Sequence for Plasma Discharge Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In plasma processing, abnormal electric discharge occurs between the substrate and the susceptor due to high DC voltage application, leading to potential substrate damage.
Innovation Solution
The method involves grounding the electrostatic chuck conductor before loading the substrate, applying a direct current voltage after loading, switching to a floating state for RF power application, and then grounding again to prevent abnormal discharge by managing the electric potential of the substrate and susceptor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high DC voltage is applied to the conductor of the electrostatic chuck prior to starting plasma processing, then the substrate can be held firmly on the susceptor, but abnormal electric discharge occurs between the substrate and susceptor causing substrate damage
Solution Approach 1:
The patent applies preliminary grounding action to the susceptor before applying high DC voltage to the electrostatic chuck conductor. This preliminary grounding prevents abnormal electric discharge by providing a discharge path for accumulated charges, allowing the substrate to be held firmly without damage
Solution Approach 2:
The patent introduces an intermediary grounding connection between the susceptor and chamber wall. This intermediary provides a controlled path for electric charges to dissipate, mediating between the high voltage conductor and the substrate to prevent harmful discharge while maintaining holding force
2Productivity
If the susceptor is kept in electrically floating state for RF power application, then plasma processing can be performed effectively, but electric potential difference causes abnormal discharge through heat transfer gas
Solution Approach 1:
The patent applies preliminary grounding to the susceptor before applying RF power. This preliminary action ensures that when the susceptor transitions to floating state for plasma processing, abnormal discharge is prevented by the pre-established reference potential and discharge paths
Solution Approach 2:
The patent employs periodic switching between grounded and floating states of the susceptor. During plasma processing, the susceptor alternates between these states to maintain effective plasma generation while periodically dissipating accumulated charges to prevent abnormal discharge
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 effectively prevents abnormal electric discharge, enhancing the yield rate in plasma processing by ensuring the substrate remains at ground potential, thus avoiding damage.
Implementation Method 1
A high DC voltage of, e.g., 2 to 3 kV, is applied to the conductor to generate an electrostatic force in the substrate mounted on the susceptor, thereby attracting and holding the substrate with a Coulomb force
Implementation Method 2
If the high DC voltage is applied to the conductor of the electrostatic chuck, the electric potential of the substrate and the susceptor is instantly increased by electrostatic induction up to substantially the same electric potential as the high DC voltage
Implementation Method 3
a RF power supply arranged outside the processing chamber applies a RF power of a specified frequency to the susceptor via a matching unit
Implementation Method 4
a heat transfer gas (typically, a helium gas) is supplied at a predetermined pressure to the rear surface of the substrate through a gas flow path formed in the susceptor
Data Source
AI summary
In a plasma processing method, a conductor of an electrostatic chuck (ESC) and an electrode are electrically grounded prior to starting the plasma processing. A DC voltage with a polarity is applied to the conductor at a first time point after loading a substrate on the electrode. Then, the electrode is switched from an electrically grounded state to an electrically floating state at a second time point. A RF power is then applied to the electrode at a third time point. The application of the RF power is stopped at a fourth time point after a specified time has lapsed from the third time point. Then, the electrode is switched from the electrically floating state to the electrically grounded state at a fifth time point. Thereafter, the application of the DC voltage is stopped and the conductor is restored to a ground potential at a sixth time point.