Capacitive Coupling Plasma Electrode Segmentation
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Solution Overview
Problem
Plasma processing apparatuses of the capacitive coupling type face challenges in achieving uniform plasma density due to high-frequency RF power application, leading to center-fast states and inefficient energy use in existing solutions.
Innovation Solution
A plasma processing apparatus with a first electrode having an outer and inner portion, where RF power is applied to the outer portion and a DC voltage is applied to the inner portion, allowing for controlled plasma distribution and uniformity through the combination of RF and DC electric fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-frequency RF power is applied to the upper electrode to generate higher density plasma, then plasma density is improved, but plasma uniformity deteriorates due to center-fast state
Solution Approach 1:
The upper electrode is divided into a central portion and a peripheral portion, with each portion receiving different power frequencies. The central portion receives high-frequency RF power (50 MHz or more) for high plasma density, while the peripheral portion receives low-frequency RF power (27 MHz or less) for uniform plasma distribution, thereby resolving the center-fast state issue.
Solution Approach 2:
Different regions of the upper electrode are assigned different electrical characteristics. The central portion is configured to accept high-frequency power for localized high-density plasma generation, while the peripheral portion accepts low-frequency power to maintain overall uniformity. This local differentiation allows simultaneous optimization of both plasma density and uniformity.
2Productivity
If high-frequency RF power is applied to the upper electrode, then plasma generation efficiency is improved, but energy loss increases due to skin effect concentration
Solution Approach 1:
The power application is segmented by frequency and location. High-frequency power is applied only to the central portion where skin effect concentration occurs, maximizing plasma generation efficiency in that region. Low-frequency power is applied to the peripheral portion where skin effect is less pronounced, reducing overall energy loss while maintaining plasma generation.
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 enables high plasma uniformity and arbitrary plasma distribution, improving etching processes by controlling plasma density at the central and peripheral regions of the substrate, reducing energy loss, and maintaining high-density plasma generation even at low pressures.
Implementation Method 1
an RF (radio frequency) is applied to one of the electrodes to form an RF electric field between the electrodes. The process gas is ionized into plasma by the RF electric field
Implementation Method 2
The process gas is ionized into plasma by the RF electric field, thereby performing a plasma etching process on a semiconductor wafer
Implementation Method 3
a DC voltage is applied to the inner portion of the first electrode, allowing for controlled plasma distribution and uniformity through the combination of RF and DC electric fields
Implementation Method 4
it is transmitted through the electrode surface by means of the skin effect and is concentrated at the central portion of the electrode bottom surface (plasma contact surface)
Implementation Method 5
the high resistivity member is employed for the bottom surface central portion of an upper electrode to consume more RF power as Joule heat there
Data Source
AI summary
A plasma processing apparatus includes a process container configured to accommodate a target substrate and to be vacuum-exhausted. A first electrode and a second electrode are disposed opposite each other within the process container. The first electrode includes an outer portion and an inner portion both facing the second electrode such that the outer portion surrounds the inner portion. An RF power supply is configured to apply an RF power to the outer portion of the first electrode. A DC power supply is configured to apply a DC voltage to the inner portion of the first electrode. A process gas supply unit is configured to supply a process gas into the process container, wherein plasma of the process gas is generated between the first electrode and the second electrode.