Variable Impedance Transmission Line for Plasma Etch Uniformity
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Solution Overview
Problem
In semiconductor manufacturing, there is an imbalance in plasma density within process chambers, leading to differences in etch rates between the central and edge regions of substrates during etching processes, necessitating improved methods for uniform etch rate control.
Innovation Solution
The characteristic impedance of high-frequency transmission lines used to supply RF power to the substrate's support plate is varied by adjusting the permittivity and geometry of the inner and outer conductors, allowing for precise control of plasma density distribution across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma generation methods are used with fixed impedance transmission lines, then the etching process can be performed, but etch rate uniformity across the substrate deteriorates due to plasma density imbalance between central and edge regions
Solution Approach 1:
The patent applies dynamics by making the transmission line impedance adjustable rather than fixed. The system dynamically changes the characteristic impedance of the transmission line connecting the RF power supply to the lower electrode, allowing optimization of power distribution across different substrate regions during the etching process to achieve uniform etch rates.
Solution Approach 2:
The patent changes the electrical parameter (characteristic impedance) of the transmission line to control plasma density distribution. By adjusting the impedance value, the system modifies how RF power is transmitted to the electrode, thereby controlling the plasma generation characteristics and achieving uniform etching across the substrate surface.
2Manufacturing precision
If RF power is supplied through fixed impedance transmission lines, then the plasma generation process is simple, but plasma density becomes imbalanced leading to non-uniform etching
Solution Approach 1:
The transmission line is designed with adjustable impedance capability, transforming a static component into a dynamic one that can be tuned during operation. This allows the system to optimize plasma density uniformity by adapting the impedance matching conditions according to the specific etching requirements and substrate characteristics.
Solution Approach 2:
The characteristic impedance of the transmission line is used as a controllable parameter to influence plasma generation. By varying this electrical parameter, the system achieves uniform plasma density distribution across the substrate, resolving the contradiction between manufacturing precision and ease of manufacture.
3Manufacturing precision
If the characteristic impedance of the transmission line is adjusted to control plasma density, then etch rate uniformity improves, but the device complexity increases due to additional control mechanisms
Solution Approach 1:
The patent utilizes characteristic impedance as a key control parameter for managing plasma density and etch rate uniformity. By systematically adjusting this electrical parameter through controlled impedance matching networks or variable impedance transmission lines, the system achieves precise etch rate control while managing the associated device complexity.
Solution Approach 2:
The system likely incorporates feedback mechanisms to monitor etching uniformity and adjust the transmission line impedance accordingly. This closed-loop control allows the system to automatically optimize plasma density distribution, improving etch rate uniformity while the control system manages the complexity of impedance adjustment.
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 enhances the uniformity of etch rates across the substrate by adjusting the impedance of the high-frequency transmission lines, ensuring consistent processing across both central and edge regions.
Implementation Method 1
a high-frequency transmission line through which the high-frequency power is supplied from the high-frequency power supply to the support plate
Implementation Method 2
a plasma generation unit that excites the gas in the chamber into a plasma state
Data Source
AI summary
Disclosed is an apparatus for treating a substrate. The apparatus includes a chamber having a space therein in which the substrate is treated, a support unit that supports the substrate in the chamber, a gas supply unit that supplies gas into the chamber, and a plasma generation unit that excites the gas in the chamber into a plasma state. The support unit includes a support plate on which the substrate is placed, a high-frequency power supply that supplies high-frequency power to the support plate, and a high-frequency transmission line through which the high-frequency power is supplied from the high-frequency power supply to the support plate. Characteristic impedance of the high-frequency transmission line is variable.