Plasma Processing Apparatus Capacitance Control
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Solution Overview
Problem
Conventional capacitively coupled plasma processing apparatuses experience non-uniform plasma distribution and deposit film adherence issues, particularly at high radio frequency frequencies, leading to compromised in-surface processing uniformity and potential interference in subsequent processes.
Innovation Solution
A plasma processing apparatus with a capacitance varying unit that adjusts electrostatic capacitance based on process conditions and substrate number, allowing for controlled plasma density distribution and preventing deposit film adherence by switching between high and low capacitance modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the frequency of radio frequency power is increased to generate high-density plasma, then plasma density is improved, but in-surface uniformity of the process deteriorates
Solution Approach 1:
The patent applies local quality by creating different electrical conditions in different regions of the processing chamber. Specifically, it introduces a plurality of electrodes with different potentials (including floating electrodes and electrodes at different RF phases) to create localized plasma density variations that compensate for the natural central concentration effect, thereby achieving uniform plasma distribution across the substrate surface while maintaining high overall plasma density
Solution Approach 2:
The patent employs dynamics by using multiple radio frequency power sources operating at different phases and amplitudes that can be dynamically adjusted. This allows the plasma density distribution to be actively controlled and optimized in real-time, enabling uniform plasma generation across the entire processing area even at high frequencies where static single-point RF application would create non-uniform distribution
2Quantity of substance
If radio frequency power is applied to generate plasma, then plasma generation is achieved, but deposit films adhere to electrodes affecting subsequent processes
Solution Approach 1:
The patent applies periodic action by implementing alternating plasma generation and cleaning cycles. During plasma generation phases, processing is performed; during cleaning phases, reverse polarity is applied or oxygen plasma is introduced to remove deposit films from electrodes. This periodic switching prevents harmful deposit accumulation while maintaining effective plasma generation for processing
Solution Approach 2:
The patent converts the harmful effect of deposit film adherence into a beneficial cleaning mechanism. By applying reverse polarity or oxygen plasma to the electrodes, the accumulated deposits are sputtered or oxidized and removed. The same electrode structure that accumulates deposits during processing becomes the platform for their removal, transforming a harmful byproduct into a controllable cleaning opportunity
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 solution enhances plasma processing uniformity and stability, preventing deposit film adherence and maintaining consistent results despite changes in processing environments over time.
Implementation Method 1
the first electrode is connected to the processing vessel via an insulator or a space, and is electrically coupled to a ground potential via a capacitance varying unit whose electrostatic capacitance is variable
Implementation Method 2
Electrons are accelerated by an electric field formed by the radio frequency voltage to collide with a processing gas. As a result of ionization by the collision between the electrons and the processing gas, a plasma is generated
Implementation Method 3
a variable capacitor, 86, whose capacitance can be varied, in the space 50
Data Source
AI summary
A plasma processing method performs a desired plasma process on substrates by using a plasma generated in a processing space. A first and a second electrode are disposed in parallel in a processing vessel that is grounded, the substrate is supported on the second electrode to face the first electrode, the processing vessel is vacuum evacuated, a desired processing gas is supplied into the processing space formed between the first electrode, the second electrode and a sidewall of the processing vessel, and a first radio frequency power is supplied to the second electrode. The first electrode is connected to the processing vessel via an insulator or a space, and is electrically coupled to a ground potential via a capacitance varying unit whose electrostatic capacitance is varied based on a process condition of the plasma process performed on the substrate.