Plasma Control System with Variable Reactance for Uniform Current
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Solution Overview
Problem
Existing plasma processing systems with long antennas struggle to achieve uniform plasma density along the longitudinal direction, especially when handling large substrates, due to non-uniform current distribution and electrostatic coupling issues.
Innovation Solution
A plasma control system with reactance variable elements and drive parts, along with current detecting and control apparatus, adjusts the reactance of antennas to ensure uniform current flow, using a control apparatus to output signals that equalize current values across the antennas, and a configuration with variable capacitors and coolants to reduce impedance and prevent arc discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If long antennas are used to handle large substrates, then the substrate coverage area is improved, but the plasma density uniformity along the longitudinal direction deteriorates
Solution Approach 1:
The patent applies reactance variable elements (variable capacitors) to the antenna system, allowing the electrical characteristics of the antennas to be dynamically adjusted. By changing the reactance values along the longitudinal direction of the antennas, the system can compensate for non-uniform current distribution and achieve uniform plasma density while maintaining long antenna dimensions for large substrate coverage.
2Adaptability or versatility
If long antennas are used, then the substrate processing capability is improved, but electrostatic coupling between antennas and vacuum container walls causes harmful current flow
Solution Approach 1:
The patent changes the electrical parameters (reactance values) of the antenna system by incorporating variable capacitors. By adjusting the capacitance values, the resonant frequency and impedance characteristics of the long antennas are modified, which reduces electrostatic coupling effects between the antennas and vacuum container walls, thereby minimizing harmful current flow while maintaining the ability to process large substrates.
3Length of stationary object
If long antennas are used, then the substrate size handling is improved, but current distribution along the antenna length becomes non-uniform
Solution Approach 1:
The patent implements reactance variable elements at different positions along the antenna structure, creating local variations in electrical characteristics. This allows the current distribution to be locally adjusted at different segments of the long antenna, compensating for the natural non-uniformity that occurs in long antenna structures and achieving overall uniform current distribution.
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
The system generates a uniform plasma along the longitudinal direction of long antennas, effectively handling large substrates by equalizing current flow and reducing impedance, while preventing arc discharge and maintaining stable capacitance.
Implementation Method 1
an inductively-coupled plasma generated by causing a high frequency current to flow through an antenna
Implementation Method 2
a first reactance variable element configured to be disposed between the first antenna and the second antenna and have a reactance changing in accordance with movement of a movable element
Implementation Method 3
a plasma processing apparatus having a configuration in which an inductively-coupled plasma (abbreviated to ICP) is generated
Data Source
AI summary
A plasma control system comprises: a high frequency power source; a first antenna connected at one end to the high frequency power source; a second antenna connected at one end to another end of the first antenna; a first variable reactance element provided between the first antenna and the second antenna; a first drive part for the first variable reactance element; a second variable reactance element connected to another end of the second antenna; a second drive part for the second variable reactance element; a first current detection part detecting the current in the one end of the first antenna; a second current detection part detecting the current between the first antenna and the second antenna; a third current detection part detecting the current in the other end of the second antenna; and a control device controlling the first drive part and the second drive part.