Edge Ring Bypass Circuit for Plasma Etch Tilt Angle Control
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Solution Overview
Problem
In plasma processing for semiconductor manufacturing, the edge ring in plasma processing apparatuses is consumed over time, leading to a change in the shape of the sheath above the wafer, causing an inclination of the ion incidence direction, which complicates the control of the tilt angle of concave portions formed in the edge region of the wafer, especially when initial tilt angles differ for various high-frequency powers.
Innovation Solution
A plasma processing apparatus is designed with a bypass circuit that adjusts the power supply to the edge ring, allowing for the control of the initial tilt angle for each frequency, and a tilt control knob that adjusts the impedance of the RF filter, DC voltage, and lifting device to precisely control the tilt angle, ensuring uniformity across different high-frequency powers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the edge ring is used for plasma processing over time, then the operational lifespan is extended, but the edge ring is consumed and the sheath shape changes causing ion incidence direction to incline
Solution Approach 1:
The bypass circuit is configured to supply power to the edge ring before and during plasma processing to proactively compensate for edge ring consumption. This preliminary action maintains the sheath shape and ion incidence angle before significant degradation occurs, extending operational lifespan while preserving precision
Solution Approach 2:
The system dynamically adjusts the power supply parameters (frequency and amplitude) to the edge ring through the bypass circuit based on real-time processing conditions. By changing electrical parameters, the system compensates for physical wear of the edge ring, maintaining consistent tilt angle control throughout extended operation
2Adaptability or versatility
If different high-frequency powers are applied to control plasma processing, then processing flexibility is improved, but initial tilt angles differ for various powers making control complicated
Solution Approach 1:
The bypass circuit is designed as a universal power supply system that can deliver different high-frequency powers to the edge ring while maintaining consistent tilt angle control. This multi-functional circuit handles various power levels through a unified control mechanism, providing processing flexibility without increasing control complexity
Solution Approach 2:
The system uses feedback from the RF filter impedance changes to automatically adjust the bypass circuit power supply settings. When tilt angle deviations are detected through impedance variations, the feedback loop modifies power parameters to correct the tilt, enabling consistent control across different high-frequency powers without complex manual adjustment
3Manufacturing precision
If the RF filter impedance is adjusted to control tilt angle, then tilt angle control precision is improved, but the control range narrows
Solution Approach 1:
The bypass circuit provides dynamic power adjustment capability that complements the RF filter impedance control. By dynamically varying the power supply characteristics, the system maintains precise tilt angle control across a wide range of operating conditions, preventing the control range from narrowing while preserving precision
Solution Approach 2:
The control system is segmented into two independent but coordinated functions: the RF filter for precise tilt angle adjustment and the bypass circuit for broader operational range management. This segmentation allows each component to optimize its function without compromising the other, maintaining both precision and wide control range
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 solution enables precise control of the tilt angle, maintaining uniformity and preventing the narrowing of the control range, thereby ensuring accurate etching and extending the operational lifespan of the edge ring by optimizing power distribution and impedance adjustments.
Implementation Method 1
a source power supply configured to supply a source power for generating plasma from a gas in the chamber to the upper electrode or the lower electrode
Implementation Method 2
at least one bias power supply configured to supply one bias power or two or more bias powers having different frequencies to the lower electrode
Data Source
AI summary
A plasma processing apparatus comprising: a chamber; a substrate support disposed in the chamber and including a lower electrode, a substrate supporting surface for supporting a substrate, and an edge ring disposed to surround the substrate placed on the substrate supporting surface; an upper electrode disposed above the lower electrode; a power supply portion configured to supply two or more powers having different frequencies, the power supply portion including a source power supply configured to supply a source power for generating plasma from a gas in the chamber to the upper electrode or the lower electrode, and at least one bias power supply configured to supply one bias power or two or more bias powers having different frequencies to the lower electrode; at least one variable passive component electrically connected to the edge ring; and at least one bypass circuit that electrically connects the power supply portion and the edge ring and is configured to supply a part of at least one power selected from the group consisting of the source power and at least one bias power to the edge ring.