Coaxial RF Resonator Plasma Source With Optical Window
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Solution Overview
Problem
Existing semiconductor processing technologies face challenges in accurately monitoring plasma-based processes due to limited optical emissions when process gases are excited remotely from the wafer, leading to inaccurate characterization of the process, especially in applications where considerable time is required for reactants to interact with the wafer surface.
Innovation Solution
A coaxial radio frequency (RF) resonator-based plasma source that decouples the process volume from the operating conditions, providing a robust electromagnetic field for excitation and isolation, allowing for efficient optical monitoring of process gases at various locations within the process chamber, including before, during, and after interaction with the wafer, with a simplified design for easy maintenance and compatibility with multiple process types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If process gases are excited remotely from the wafer, then the plasma source can be isolated from the process chamber, but optical emissions are limited and process characterization becomes inaccurate
Solution Approach 1:
A window is introduced as an intermediary component that allows electromagnetic fields to pass through for plasma excitation while enabling optical signals to transmit from the plasma region to external detectors. This mediator resolves the contradiction by maintaining plasma isolation while preserving both excitation capability and optical monitoring accuracy.
2Power
If a coaxial RF resonator is used to provide robust electromagnetic field, then plasma excitation efficiency is improved, but the complexity of the plasma source increases
Solution Approach 1:
The coaxial RF resonator structure serves multiple functions simultaneously: it generates robust electromagnetic fields for efficient plasma excitation, provides a defined plasma cavity geometry, and incorporates a window that enables both field transmission and optical signal passage. This multi-functionality reduces overall system complexity despite the sophisticated resonator design.
3Object-affected harmful factors
If the plasma source is isolated from the process chamber, then contamination is reduced, but optical coupling between the plasma and monitoring system becomes difficult
Solution Approach 1:
The window acts as an intermediary that physically separates the plasma source from the process chamber (reducing contamination) while simultaneously allowing electromagnetic fields to excite the plasma and enabling optical signals to pass through for external monitoring. This single component resolves both the isolation and detection difficulties.
4Measurement precision
If process monitoring is performed at multiple locations, then comprehensive process characterization is achieved, but the number of plasma sources required increases
Solution Approach 1:
The plasma source with its window and cavity structure is designed to be relocatable and adaptable to different positions within the process chamber. A single multi-functional plasma source can be moved to various locations to perform comprehensive process characterization, eliminating the need for multiple fixed plasma sources while maintaining monitoring accuracy across different regions.
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 solution enables accurate optical monitoring of semiconductor processes by minimizing interaction with the process space, reducing contamination, and maintaining compatibility across a wide pressure range, allowing for precise characterization of process endpoints and etch depths, while being suitable for various monitoring applications and easy to maintain.
Implementation Method 1
a coaxial radio frequency (RF) resonator including a first end, a second end, an inner electrode and an outer electrode, a radio frequency interface electrically coupled to the inner and outer electrode and configured to provide an RF signal to the coaxial RF resonator
Implementation Method 2
a window positioned between the first end of the resonator and the flange, and forming one side of the plasma cavity
Data Source
AI summary
The disclosure provides a plasma source, an excitation system for excitation of a plasma, and a method of operating an excitation measurement system. In one embodiment, the plasma source includes: (1) a coaxial radio frequency (RF) resonator including a first end, a second end, an inner electrode and an outer electrode, (2) a radio frequency interface electrically coupled to the inner and outer electrode and configured to provide an RF signal to the coaxial RF resonator, (3) a flange positioned at the first end of the resonator and defining a plasma cavity, and (4) a window positioned between the first end of the resonator and the flange, and forming one side of the plasma cavity, whereby the coaxial RF resonator is isolated from the plasma.