Variable-Diameter Plasma Coil Layout to Reduce Chamber Sputtering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing substrate processing technologies face challenges in reducing sputtering on the inner walls of process chambers during plasma-excited gas processing, which leads to contamination of the substrate and degradation of film quality due to the release of chamber materials into the processing environment.
Innovation Solution
A substrate processing apparatus is designed with a resonance coil having a varying winding diameter, where the distance from the coil's inner periphery to the plasma vessel is minimized at positions of maximum current amplitude and maximized at positions of maximum voltage amplitude, reducing the electric field intensity and suppressing the generation of capacitively coupled plasma, thereby minimizing sputtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a process gas is plasma-excited in a process chamber using a coil, then substrate processing efficiency is improved, but sputtering occurs on the inner wall of the process chamber causing contamination
Solution Approach 1:
The coil winding diameter is varied locally around the plasma vessel: smaller diameter at positions where capacitively coupled plasma easily occurs (to reduce electric field intensity), and larger diameter at other positions (to maintain plasma generation efficiency). This local variation in coil geometry allows different regions to have optimized characteristics for their specific functional requirements.
Solution Approach 2:
The physical parameter of the coil (winding diameter) is changed to resolve the contradiction. By adjusting the winding diameter at different angular positions around the plasma vessel, the electric field distribution is modified to suppress sputtering while maintaining plasma generation efficiency for substrate processing.
2Quantity of substance
If high-frequency power is applied to generate plasma, then reactive species are generated for substrate processing, but ions are accelerated causing sputtering and material release
Solution Approach 1:
The coil structure is designed with non-uniform winding diameter to create local variations in electric field intensity. This ensures that regions prone to excessive ion acceleration and sputtering have reduced electric field strength, while other regions maintain sufficient field strength for reactive species generation.
Solution Approach 2:
The design converts the potentially harmful effect of electric field-induced sputtering into a beneficial configuration by strategically placing smaller coil sections at critical locations. This transforms the electric field distribution from a source of contamination to a controlled parameter that protects the chamber while enabling processing.
3Speed
If the coil is positioned close to the plasma vessel for efficient plasma generation, then processing speed increases, but electric field intensity increases causing more sputtering
Solution Approach 1:
The coil winding diameter varies locally to optimize the balance between processing speed and sputtering reduction. At positions where close positioning is necessary for efficient plasma generation, the smaller diameter compensates by reducing the electric field intensity, preventing excessive sputtering while maintaining processing speed.
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 reduces the introduction of chamber materials into the substrate films, improving film quality and process chamber integrity by minimizing sputtering and maintaining plasma density uniformity.
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
Implementation Method 3
a distance from the inner periphery of the coil to the inner periphery of the plasma vessel at a position on the coil at which an amplitude of a standing wave of a voltage applied to the coil is maximized is maximized
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.