Far Edge Electrostatic Chuck for Uniform Wafer Edge Plasma
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Solution Overview
Problem
The challenge in semiconductor device fabrication is the control of plasma interaction with the substrate, particularly in the circumferential outer region, which leads to non-uniform processing and defects due to differences in plasma coupling and temperature distribution across the electrostatic chuck.
Innovation Solution
The electrostatic chuck assembly incorporates a ceramic electrostatic chuck with a far edge electrode that extends to the edge of the chuck, allowing for independent AC biasing to create a uniform plasma sheath across the substrate. This assembly includes a thicker active far edge electrode and an embedded ground electrode to enhance plasma control and reduce chamber volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional electrostatic chuck is used, then the substrate can be supported during processing, but non-uniform plasma coupling occurs in the circumferential outer region leading to process skew and defects
Solution Approach 1:
The electrostatic chuck is segmented into multiple independent electrode regions: a central chucking electrode region and an outer far edge electrode region. Each region can be independently biased to control plasma coupling locally, thereby achieving uniform plasma distribution across the substrate surface and eliminating process skew in the circumferential outer region.
Solution Approach 2:
Different regions of the electrostatic chuck are assigned different electrical properties and functions. The central region provides standard electrostatic chucking, while the outer far edge electrode region provides enhanced plasma control. This local differentiation allows each zone to address specific plasma coupling characteristics, improving overall manufacturing precision.
2Manufacturing precision
If the electrostatic chuck design is extended to improve plasma control at the edges, then film coverage improves, but the footprint and complexity of the chuck increases
Solution Approach 1:
The far edge electrode serves multiple functions: it provides electrostatic chucking force at the substrate periphery, controls plasma coupling in the circumferential outer region, and helps shape the plasma sheath uniformly across the substrate. This multi-functionality achieves improved film coverage without proportionally increasing device complexity.
Solution Approach 2:
The electrode structure extends in the radial dimension beyond the traditional chucking electrode boundary. By adding this outer radial dimension with the far edge electrode, the system gains additional control over edge plasma behavior, improving film coverage uniformity while maintaining a compact overall footprint.
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 achieves improved film coverage and uniformity across the substrate, particularly at the outer circumferential portion, by controlling the plasma interaction. It also reduces the footprint of the electrostatic chuck and enhances reliability by preventing plasma light-up in gaps, thus improving the overall semiconductor device fabrication process.
Implementation Method 1
a ceramic electrostatic chuck having a body, the body having an outer diameter, a first side configured to support a substrate
Implementation Method 2
allowing for independent AC biasing to create a uniform plasma sheath across the substrate
Data Source
AI summary
A substrate support for use in a substrate processing chamber includes a ceramic electrostatic chuck having a body having an outer diameter, a first side configured to support a substrate and a second side opposite the first side, and a thickness between the first side and the second side, wherein the body comprises at least one chucking electrode having a radially outer surface and a far edge electrode disposed adjacent to the chucking electrode and extending radially outwardly of the at least one chucking electrode.