ESC Blocking Electrode Layout for Wafer Edge RF Uniformity
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Solution Overview
Problem
Semiconductor processing tools with electrostatic chucks (ESCs) face challenges in achieving uniform processing due to non-uniformities caused by the blocking electrode's design, particularly the spokes, which lead to variations in RF density and plasma interaction.
Innovation Solution
The design incorporates an electrostatic chuck with a blocking electrode featuring an annular portion and multiple spokes, where the number of spokes is based on the RF power frequency, and the geometry is optimized to reduce non-uniformities by controlling the plasma formation and interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a blocking electrode with spokes is used in the electrostatic chuck, then the wafer can be clamped and plasma can be generated, but non-uniformities in RF density and plasma interaction occur at the wafer edge
Solution Approach 1:
The blocking electrode is designed with an asymmetric configuration where the annular portion has a different geometry than traditional circular designs, and the spokes are positioned at specific asymmetric angles. This asymmetric design redistributes the RF density more uniformly across the wafer surface, reducing edge non-uniformities while maintaining effective plasma generation and wafer clamping.
2Manufacturing precision
If the blocking electrode geometry is optimized to reduce non-uniformities, then processing uniformity improves, but the design complexity increases
Solution Approach 1:
The blocking electrode is segmented into distinct functional portions: an annular portion that provides overall plasma confinement and multiple spoke elements that radially distribute RF energy. This segmentation allows each portion to be independently optimized for its specific function while working together to achieve uniform processing, balancing design complexity with performance improvement.
3Manufacturing precision
If the number of spokes is increased based on RF power frequency, then plasma uniformity improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The number of spokes in the blocking electrode is specifically determined as a function of the RF power frequency used in the plasma process. By establishing this quantitative relationship, the design optimizes plasma density uniformity for different operating frequencies without requiring excessive spokes, thus balancing manufacturing complexity with plasma uniformity requirements.
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 design improves processing uniformity by reducing peak and average non-uniformities at the wafer edge, allowing for more controlled plasma properties and enhanced semiconductor wafer processing outcomes.
Implementation Method 1
one or more clamping electrodes beneath the upper surface, wherein the one or more clamping electrodes are configured to, when powered, electrostatically clamp the wafer to the upper surface
Implementation Method 2
Plasma sources are used to create a plasma that, when a process gas is flowed into them, creates neutral particles, ions, and/or radicals of the process gas
Implementation Method 3
Pedestals in the electrostatic chuck (ESC) may be used to generate an electromagnetic field that clamps the substrate to the ESC and/or bias towards the ESC
Data Source
AI summary
Electrostatic chuck (ESC) apparatuses and systems are provided. An ESC may have one or more chucking electrodes and a blocking electrode that surrounds the chucking electrodes. The blocking electrode may reduce non-uniformities in semiconductor processing operations performed with the ESC. In some implementations, the blocking electrode is positioned beneath the chucking electrodes.