Microwave Cavity Conductor Layout for Uniform High-Pressure Plasma
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Solution Overview
Problem
Existing plasma processing apparatuses face challenges in achieving uniform plasma processing characteristics over a wide pressure range, particularly at high pressures, due to localized plasma generation and isotropic diffusion, leading to non-uniform etching rates across the wafer surface.
Innovation Solution
A plasma processing apparatus is designed with a ring-shaped conductor and a circular conductor within a cavity resonator, combined with a magnetic field forming mechanism, to uniformly distribute plasma across the wafer surface by adjusting the magnetic field distribution and guiding microwaves outward from the central axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If ECR plasma generation method is used, then plasma can be efficiently generated in low pressure range, but plasma generation becomes localized at central axis under high pressure conditions
Solution Approach 1:
The microwave introduction system is segmented into multiple independent waveguides (central waveguide and surrounding waveguides), allowing separate control of microwave power distribution to different regions of the discharge chamber. This enables independent optimization of plasma generation in central and peripheral regions, resolving the localization problem while maintaining overall efficiency.
Solution Approach 2:
Different microwave power levels are applied to different spatial regions through the segmented waveguide system. The central waveguide provides focused power for efficient plasma generation, while surrounding waveguides supply additional power to peripheral regions to ensure uniform plasma distribution across the entire discharge chamber under high pressure conditions.
2Quantity of substance
If microwave power is increased to improve plasma generation efficiency, then plasma density increases, but plasma localization at central axis becomes more severe
Solution Approach 1:
The total microwave power is segmented and distributed through multiple waveguides positioned at different locations. This allows the plasma density to be increased overall while maintaining uniform spatial distribution, as each waveguide contributes to plasma generation in its respective region rather than concentrating all power at the center.
Solution Approach 2:
The microwave power distribution is extended from a single central point to a two-dimensional array of waveguides (central plus surrounding waveguides). This spatial arrangement in multiple dimensions enables uniform plasma density increase across the discharge chamber cross-section, preventing central axis localization even at high power levels.
3Device complexity
If single waveguide configuration is used, then device complexity is reduced, but plasma uniformity across wafer surface deteriorates
Solution Approach 1:
The microwave introduction system is divided into multiple waveguides (central and surrounding waveguides) that can be independently controlled. This segmentation allows precise adjustment of power distribution to achieve uniform plasma processing across the wafer surface, with the added benefit that not all waveguides need to be active simultaneously, managing complexity through selective operation.
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 apparatus achieves highly uniform plasma processing across a wide pressure range by suppressing plasma localization at the central axis, ensuring consistent etching rates and uniformity on the wafer surface.
Implementation Method 1
a cavity resonator which resonates a microwave transmitted from the radio frequency power supply through a waveguide
Implementation Method 2
a magnetic field forming mechanism which forms a magnetic field in the processing chamber
Implementation Method 3
The ECR is a resonance phenomenon that occurs when there is a match between an electromagnetic wave frequency introduced from an electromagnetic wave generation source and a cyclotron frequency of electrons by a magnetic field formed by an electromagnetic coil. Plasma is generated when high-energy electrons accelerated by the ECR collide with gas molecules and are ionized.
Data Source
AI summary
A plasma processing apparatus includes: a processing chamber in which a sample is subjected to plasma processing, including, at an upper side therein, a dielectric plate, through which microwaves are transmitted; a radio frequency power supply which supplies radio frequency power for the microwaves; a cavity resonator which resonates microwaves transmitted from the radio frequency power supply through a waveguide and is placed above the dielectric plate; and a magnetic field forming mechanism which forms a magnetic field in the processing chamber. The plasma processing apparatus further includes: a ring-shaped conductor placed inside the cavity resonator; and a circular conductor which is placed inside the cavity resonator and placed in an opening at the center of the ring-shaped conductor.