Edge Ring Electric Field Control for Uniform Wafer Etching
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Solution Overview
Problem
As semiconductor devices undergo miniaturization and increased integration, the edge region of semiconductor wafers experiences non-uniform etching due to plasma sheath curvature, leading to angled recesses and potential yield loss from Etch-Induced Overlay Shift (EIOS) and short circuits.
Innovation Solution
The use of a tunable doping edge ring with controlled electric field adjustments, applying DC and RF voltages to maintain a planar plasma sheath over the wafer and edge ring, ensures perpendicular ion acceleration and uniform etching profiles, extending the edge ring's lifespan and reducing yield loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etching is used without edge ring control, then etching process is simple, but etching uniformity deteriorates in edge regions due to plasma sheath curvature
Solution Approach 1:
The patent applies parameter changes by adjusting the DC voltage applied to the edge ring to control the plasma sheath shape. By varying the voltage parameter, the system transitions from a curved plasma sheath (causing non-uniform etching) to a planar plasma sheath (achieving uniform etching). This directly addresses the technical contradiction by using electrical parameter control to improve etching uniformity while managing system complexity.
Solution Approach 2:
The edge ring acts as an intermediary component between the plasma source and the wafer. It mediates the plasma sheath formation by providing a controllable electrical boundary that shapes the plasma distribution. This intermediary device enables uniform etching across the wafer surface without requiring fundamental changes to the entire etching system.
2Manufacturing precision
If DC voltage is applied to edge ring to maintain planar plasma sheath, then etching uniformity is improved, but energy consumption increases
Solution Approach 1:
The system optimizes energy consumption by dynamically adjusting the DC voltage parameter applied to the edge ring. Rather than maintaining constant high voltage, the system modifies the voltage level based on process requirements, thereby reducing unnecessary energy consumption while preserving etching uniformity. This parameter optimization resolves the contradiction between precision and energy efficiency.
3Manufacturing precision
If edge ring is used to control plasma sheath, then etching uniformity is improved, but device complexity increases
Solution Approach 1:
The edge ring is designed as a multi-functional component that simultaneously serves as a plasma boundary control element, a voltage application interface, and a structural support feature. By consolidating multiple functions into a single component, the patent reduces overall device complexity while maintaining the ability to control plasma sheath and achieve uniform etching.
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 approach achieves more uniform etching profiles across the wafer, minimizes yield loss, and extends the edge ring's operational life by compensating for wear and maintaining plasma sheath planarity, thus overcoming non-uniformity and reducing replacement costs.
Implementation Method 1
plasma sheath curvature
Implementation Method 2
controlled electric field adjustments, applying DC and RF voltages
Implementation Method 3
perpendicular ion acceleration
Data Source
AI summary
Semiconductor devices, methods of manufacturing the semiconductor device and tools are disclosed herein. Some methods include providing an electrostatic chuck and placing an edge ring adjacent to the electrostatic chuck. The electrostatic chuck includes a first electrode to generate a sheath at a first distance over the electrostatic chuck. The edge ring includes a coil and a second electrode to generate an electric field control to maintain a portion of the sheath over the edge ring in a coplanar orientation with the portion of the sheath over the electrostatic chuck.