Plasma Processing Apparatus with Microwave Rotation Generator
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Solution Overview
Problem
The existing plasma processing apparatuses face challenges in achieving uniform etching rates and axial symmetry due to elliptical distribution of plasma and biased gas flows, especially in microfabrication and multi-layer etching, where the elliptical shape of the microwave electric field and asymmetric gas extraction complicate the uniformity of processing conditions.
Innovation Solution
A plasma processing apparatus is designed with a coaxial configuration of the gas supply, microwave introduction, and vacuuming units, incorporating a microwave rotation generator to rotate the polarized surface of the microwave, ensuring axially symmetric distribution of the electric field and gas flow, thereby stabilizing the plasma and improving uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a circular wave guide is used to introduce microwave in TE11 mode, then the microwave can be efficiently introduced into the chamber, but the electric field is distributed in an elliptical shape causing non-uniform plasma distribution
Solution Approach 1:
The patent applies asymmetry by intentionally introducing an asymmetric element (dielectric plate) into the symmetric circular wave guide system. This creates a controlled asymmetry that rotates the electric field distribution from a fixed elliptical pattern to a rotating pattern, achieving uniform time-averaged distribution while maintaining efficient microwave coupling.
Solution Approach 2:
The patent changes the physical parameter of the microwave field by introducing a dielectric plate with specific dielectric constant, which alters the phase velocity and wavelength of the microwave. This parameter change enables the transformation of the electric field distribution pattern from elliptical to uniformly rotating, solving the uniformity problem while preserving energy efficiency.
2Device complexity
If the vacuuming unit extracts gas only from one side of the exhaust duct, then the structure is simple, but biased gas flows are caused on the wafer
Solution Approach 1:
The patent segments the exhaust function by providing multiple exhaust ports distributed around the chamber perimeter instead of a single centralized exhaust. This segmentation allows gas to be extracted from multiple locations simultaneously, eliminating biased flow patterns while maintaining structural simplicity through modular port configuration.
Solution Approach 2:
The patent creates equipotential gas flow conditions by strategically positioning multiple exhaust ports around the chamber to establish balanced pressure distribution. This ensures uniform gas flow across the wafer surface by eliminating pressure gradients that would otherwise cause biased flows, while keeping the exhaust system structurally simple.
3Manufacturing precision
If the microwave electric field is rotated using a dielectric plate, then the uniformity of etching rate is improved, but the device complexity increases
Solution Approach 1:
The patent uses a dielectric plate as an intermediary element that passively rotates the microwave electric field through its dielectric properties. This intermediary approach achieves field rotation without requiring active mechanical rotation mechanisms, thereby improving etching uniformity while minimizing the increase in device complexity.
Solution Approach 2:
The patent replaces any potential mechanical rotation system with a static dielectric plate that achieves the same effect through electromagnetic interaction. This substitution eliminates moving parts and mechanical complexity while maintaining the ability to rotate the electric field for uniform plasma 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
This configuration results in significantly improved uniformity of the wafer surface, achieving axial symmetry in etching rates and dimensions, particularly effective in microfabrication and multi-layer etching processes, enhancing the precision and consistency of the etching process.
Implementation Method 1
generates plasma in the chamber using interaction of the introduced microwave with a magnetic field produced by a magnetic field-producing coil
Implementation Method 2
incorporating a microwave rotation generator to rotate the polarized surface of the microwave, ensuring axially symmetric distribution of the electric field
Data Source
AI summary
A plasma processing apparatus includes: a decompression chamber of which the inside is depressed; a gas supply unit that supplies process gas into said chamber; a microwave supply unit that supplies a microwave into the chamber to generate plasma; an object-placing electrode where a processing material, is placed and which holds the processing material in the chamber; and a vacuuming unit that is connected to the chamber to discharge the gas in the chamber, in which the chamber, a part for providing gas into the chamber of the gas supply unit, a part for introducing a microwave into the chamber of the microwave supply unit, the object-placing electrode, and the vacuuming unit are disposed coaxially with the center axis of the chamber, and the part for introducing a microwave includes a microwave rotation generator that rotates a polarization plane of the input microwave and supplies the microwave to the chamber.