Upper Electrode Cover Layer Suppresses Abnormal Discharges
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Solution Overview
Problem
Abnormal discharges in upper electrodes of capacitively-coupled plasma processing apparatuses are not effectively suppressed, leading to inefficiencies in plasma processing.
Innovation Solution
The upper electrode is designed with a conductor first member and a second member having a cover layer with a secondary electron emission coefficient less than 1, which reduces secondary electron emission and exhausts electrons to ground, thereby suppressing abnormal discharges. The cover layer can be made of materials like diamond-like carbon, amorphous carbon, or silicon carbide, and may include an insulating layer and a conductive member for further suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional upper electrode structure is used, then the plasma processing can be performed, but abnormal discharges occur leading to processing inefficiency
Solution Approach 1:
The patent changes the material parameter of the upper electrode surface by forming a silicon oxide layer or using silicon carbide material, which has different electrical properties (higher resistivity, lower secondary electron emission coefficient) compared to conventional conductive materials. This parameter change suppresses abnormal discharges while maintaining plasma processing capability
Solution Approach 2:
The patent employs composite material structures where a silicon-based layer (silicon oxide or silicon carbide) is combined with conductive materials. The silicon oxide layer formed on the silicon electrode plate or the silicon carbide material creates a composite structure that suppresses secondary electron emission and abnormal discharges while allowing controlled plasma generation
2Reliability
If the secondary electron emission is not suppressed, then electrons can be emitted for plasma generation, but abnormal discharges occur in the upper electrode
Solution Approach 1:
The patent changes the surface material parameter of the upper electrode to silicon oxide or silicon carbide, which have inherently lower secondary electron emission coefficients compared to conventional metals. This parameter change directly reduces secondary electron emission from the electrode surface, preventing abnormal discharge conditions
Solution Approach 2:
The patent converts the potentially harmful effect of secondary electron emission into a beneficial control mechanism. By using silicon oxide or silicon carbide materials with controlled electron emission properties, the electrode can still generate necessary electrons for plasma while suppressing excessive secondary electron emission that causes abnormal discharges
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 abnormal discharges in the upper electrode, maintaining potential difference and improving plasma processing efficiency by reducing secondary electron emission and exhausting electrons to ground.
Implementation Method 1
The secondary electron emission coefficient of the cover layer is smaller than 1
Implementation Method 2
electrons are exhausted to ground
Data Source
AI summary
An upper electrode disclosed configures a shower head in a capacitively-coupled plasma processing apparatus. The upper electrode includes a first member and a first member. The first member includes a conductor. The first member provides a plurality of first holes. The plurality of first holes penetrate the first member. The second member includes a main body and a cover layer. The main body includes a conductor and is provided above the first member. The cover layer covers the surface of the main body. The second member provides one or more second holes. The secondary electron emission coefficient of the cover layer is smaller than 1.