Electrostatic Chuck Edge Structure for Uniform Plasma Sheath
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Solution Overview
Problem
Existing plasma processing systems face challenges with arcing and non-uniformity of deposited material layers, particularly at the substrate edge, due to asymmetry in the RF return path and geometry of the pedestal heater.
Innovation Solution
The substrate support is designed with angled walls and upper surfaces to expand the plasma radially outward from the substrate edge, improving plasma sheath uniformity and reducing arcing. This design includes a protrusion with stepped surfaces to enhance plasma distribution and prevent substrate sliding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional substrate support with symmetric geometry is used, then the manufacturing cost is low and the structure is simple, but arcing occurs along the RF return path and plasma sheath uniformity is poor at the substrate edge
Solution Approach 1:
The substrate support employs an asymmetric geometry design where the pedestal heater has a non-circular cross-section (e.g., rectangular or elliptical) and the RF return path is positioned asymmetrically relative to the substrate center. This asymmetric configuration modifies the plasma sheath distribution and RF current flow patterns, preventing arcing along the RF return path while maintaining manufacturing feasibility through standard machining processes
Solution Approach 2:
The invention introduces vertical dimensionality to the substrate support design by incorporating a stepped or tiered pedestal structure with different height levels. This vertical variation in the pedestal height creates non-uniform plasma sheath thickness across the substrate surface, improving plasma distribution uniformity at the substrate edge and reducing arcing tendencies through three-dimensional geometric control
2Manufacturing precision
If the pedestal heater geometry is modified to improve plasma sheath uniformity, then deposition uniformity improves, but the manufacturing complexity and cost increase
Solution Approach 1:
The pedestal heater is segmented into multiple distinct components including a separate pedestal body, heater element, and RF return path structure. This segmentation allows each component to be manufactured independently using standard processes and then assembled, achieving complex geometric configurations for improved plasma uniformity without requiring complex single-piece manufacturing
Solution Approach 2:
The substrate support structure is designed to perform multiple functions: the pedestal serves as both a mechanical support and a heater mount, the heater element provides both heating and plasma generation, and the RF return path serves as both an electrical conductor and a structural component. This multi-functionality reduces the number of separate parts needed, simplifying manufacturing while achieving the desired plasma sheath uniformity through integrated design
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 improved substrate support reduces arcing and enhances deposition uniformity, leading to more consistent material layers and increased processing throughput while maintaining low manufacturing costs.
Implementation Method 1
The substrate may be held to the substrate support by vacuum, gravity, electrostatic forces, or by other suitable techniques
Implementation Method 2
The precursor gas or gas mixture in the chamber is energized (e.g., excited) into a plasma by applying a power, such as a radio frequency (RF) power, to an electrode in the chamber
Implementation Method 3
In some systems, prevention of arcing along the RF return path particularly in the proximity of the substrate support is a major challenge
Implementation Method 4
At higher processing temperature (e.g.: 650C), the substrate bow is high and ESC is used to chuck the substrate for good uniformity
Data Source
AI summary
Aspects of the present disclosure relate to one or more implementations of a substrate support for a processing chamber. In one implementation, a substrate support includes a body having a center, and a support surface on the body configured to at least partially support a substrate. The substrate support includes a first angled wall that extends upward and radially outward from the support surface, and a first upper surface disposed above the support surface. The substrate support also includes a second angled wall that extends upward and radially outward from the first upper surface, the first upper surface extending between the first angled wall and the second angled wall. The substrate support also includes a second upper surface extending from the second angled wall. The second upper surface is disposed above the first upper surface.