Resonance Coil Spacing in Plasma Units to Reduce Wall Sputtering
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Solution Overview
Problem
The existing plasma processing technologies suffer from sputtering issues on the inner walls of process chambers, which leads to contamination of substrates with material components from the chamber walls, affecting the quality of processed films.
Innovation Solution
A plasma processing apparatus is designed with a resonance coil installed around the plasma vessel, where the coil separation distance varies along its length to maximize the current amplitude at certain points and minimize the voltage amplitude at others, thereby controlling the plasma generation and reducing sputtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-frequency power is applied to an electrode to generate plasma, then substrate processing can be performed, but ions are accelerated and collide with the inner wall causing sputtering
Solution Approach 1:
A matching network is introduced as an intermediary component between the high-frequency power source and the electrode. This matching network optimizes impedance matching to control the distribution of high-frequency voltage and current, thereby reducing ion acceleration and sputtering on the chamber wall while maintaining effective plasma generation for substrate processing.
Solution Approach 2:
The patent changes the electrical parameters (voltage and current distribution) along the electrode by using a matching network with specific impedance characteristics. This parameter optimization allows the electrode to generate sufficient plasma for processing while minimizing the voltage peaks that cause ion acceleration and wall sputtering.
2Device complexity
If the coil is installed with uniform distance from the plasma vessel, then the structure is simple, but the amplitude of standing wave voltage is not optimized for sputtering reduction
Solution Approach 1:
The coil is designed with non-uniform spacing from the plasma vessel wall, creating different local conditions along its length. The spacing is specifically optimized at positions where standing wave voltage amplitude is maximized to enhance sputtering reduction effectiveness, while maintaining reasonable structural complexity.
3Object-generated harmful factors
If the distance from coil to plasma vessel is maximized at all positions, then sputtering is reduced, but plasma generation efficiency decreases
Solution Approach 1:
The coil spacing is optimized locally rather than uniformly. At positions where standing wave voltage amplitude is maximum, the coil is positioned farther from the plasma vessel to reduce sputtering. At other positions, the spacing is reduced to maintain effective plasma generation, thus balancing sputtering reduction with plasma generation efficiency.
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 configuration effectively suppresses the generation of plasma that causes sputtering on the inner walls of the process chamber, reducing the introduction of impurities into processed films and improving the overall quality and yield of semiconductor devices.
Implementation Method 1
a coil installed to wind around an outer periphery of the plasma vessel and configured to be supplied with high-frequency power
Implementation Method 2
the generated ions may be accelerated due to an effect of electric field formed by an electrode to which high-frequency power is applied, and may collide with an inner wall of the process chamber to cause sputtering
Data Source
AI summary
There is provided a plasma vessel in which a process gas is plasma-excited; a substrate process chamber which is in communication with the plasma vessel; a gas supply system supplying the process gas; and a coil installed to wind around an outer periphery of the plasma vessel and supplied with high-frequency power, wherein the coil is installed such that: a distance from an inner periphery of the coil to an inner periphery of the plasma vessel at a predetermined position on the coil is different from a distance from the inner periphery of the coil to the inner periphery of the plasma vessel at another position on the coil; and a distance from the inner periphery of the coil to the inner periphery of the plasma vessel at a position at which an amplitude of a standing wave of a voltage applied to the coil is maximized is maximized.