Ground Electrode Shield for Plasma Adhesion Control
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Solution Overview
Problem
In plasma processing apparatuses, the adhesion of reaction products to the ground electrode can impede DC voltage application, leading to unstable plasma conditions, especially when the reaction products have high adhesive force or when the process is prolonged.
Innovation Solution
An annular shield member with a protruding portion is positioned above the ground electrode, and a groove is formed at the outer peripheral portion of the ground electrode, increasing its exposed surface area and reducing adhesion, allowing stable DC voltage application over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ground electrode surface is exposed within the processing chamber to apply DC voltage, then DC voltage application is enabled, but reaction product adhesion impedes DC current flow and destabilizes plasma
Solution Approach 1:
A shield member is introduced as an intermediary component between the reaction product-laden plasma environment and the ground electrode. This shield member intercepts reaction products before they can reach and adhere to the ground electrode surface, thereby protecting the electrode's electrical functionality while maintaining plasma stability.
Solution Approach 2:
The ground electrode system is segmented into two functional parts: the ground electrode itself (providing the electrical reference) and the shield member (providing protective coverage). This segmentation allows the electrode to maintain its electrical function while the shield handles the protective function against adhesion.
2Object-affected harmful factors
If a shield wall is provided around the ground electrode to suppress adhesion, then adhesion is reduced, but function deterioration occurs over time with prolonged plasma processes
Solution Approach 1:
The shield member extends vertically above the ground electrode surface, utilizing the vertical dimension to create a protective overhang. This three-dimensional configuration allows the shield to intercept reaction products falling from the plasma zone, providing protection that extends beyond a simple planar barrier and effectively reducing adhesion on the electrode surface during prolonged operation.
3Productivity
If DC voltage is applied to improve plasma process performance, then process performance is enhanced, but reaction product adhesion impedes DC current flow
Solution Approach 1:
The shield member acts as a protective intermediary that preserves the electrical pathway for DC current flow by preventing reaction product accumulation on the ground electrode surface, thereby maintaining the reliability of DC voltage application for enhanced plasma process performance.
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 effectively suppresses reaction product adhesion to the ground electrode, maintaining stable plasma conditions and preventing function deterioration, enabling long-term stable DC voltage application.
Implementation Method 1
a high frequency power is applied to at least any one of an upper electrode and a lower electrode provided to face each other within a processing chamber and a gas is excited into plasma by electric field energy of the high frequency power
Implementation Method 2
there has been suggested a process of applying a DC voltage into a processing chamber by connecting an upper electrode to a DC power supply
Implementation Method 3
the target object is microprocessed through a plasma process, e.g., an etching process, by the generated electric discharge plasma
Data Source
AI summary
A plasma processing apparatus of exciting a processing gas into plasma by applying a high frequency power between an upper electrode and a lower electrode provided within a processing chamber and performing a plasma process on a target object to be processed with the plasma includes a DC power supply configured to apply a DC voltage to the upper electrode; a ground electrode connected to the DC power supply; and an annular shield member provided outside the ground electrode. A groove is formed into a downward recess at an outer peripheral portion of the ground electrode, and an upper end of the shield member is positioned above an upper end of the peripheral portion of the ground electrode. A protruding portion, which is protruded toward a center of the ground electrode, is formed at a portion of the shield member positioned above the ground electrode.