Variable Capacitor ICP Antenna for Plasma Uniformity
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Solution Overview
Problem
Inductively coupled plasma (ICP) methods face challenges in achieving uniform plasma density on substrate processing surfaces due to non-uniform antenna coil shapes and limited frequency adjustments, leading to variations in plasma behavior and potential damage from high ion impact energy.
Innovation Solution
An ICP antenna with a variable capacitor connected in parallel to the antenna coil, allowing for impedance adjustment and improved plasma uniformity by controlling coil current and plasma power distribution across the substrate surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional ICP antenna with fixed capacitance is used, then the antenna structure is simple, but the plasma density uniformity on the substrate surface deteriorates
Solution Approach 1:
The patent applies the dynamics principle by replacing the fixed capacitor with a variable capacitor in the ICP antenna circuit. This allows the capacitance value to be dynamically adjusted during operation, enabling optimization of plasma density uniformity across the substrate surface. The variable capacitor provides real-time adaptability to compensate for non-uniform plasma distribution without requiring complex structural modifications to the antenna itself.
Solution Approach 2:
The patent implements parameter changes by modifying the electrical parameters of the antenna circuit, specifically the capacitance value. By changing the capacitance parameter of the variable capacitor, the impedance matching and plasma coupling characteristics of the antenna are adjusted, which directly improves plasma density uniformity. This approach achieves performance improvement through parameter optimization rather than structural complexity increase.
2Quantity of substance
If high radio frequency power is supplied to generate high density plasma, then the ion density increases, but the ion impact energy increases causing substrate damage
Solution Approach 1:
The patent applies parameter changes by adjusting the capacitance value of the variable capacitor to optimize the antenna's electrical characteristics. This allows for better coupling efficiency between the RF power source and the plasma, enabling high ion density to be achieved at lower RF power levels. By changing the electrical parameters of the antenna circuit, the system can maintain high plasma density while reducing the harmful ion impact energy that would otherwise require high power input.
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 integration of a variable capacitor in the ICP antenna enhances plasma uniformity on the substrate surface, reducing high-density plasma hotspots and maintaining plasma power, thereby preventing damage from ion impact while improving processing efficiency.
Implementation Method 1
applies a high frequency to an antenna that has generally a spiral shape, and accelerates electrons of the inside of a chamber, by means of an electric filed induced according to a change of a magnetic field caused by high frequency current introduced to the antenna
Implementation Method 2
a variable capacitor connected in parallel to a portion of the antenna coil
Data Source
AI summary
Provided is an ICP antenna used in a plasma processing device. The ICP antenna includes an antenna coil having one end connected to an RF power source through an impedance matching circuit and the other end that is grounded; and a variable capacitor connected in parallel to a portion of the antenna coil.