RF Impedance Transformation Circuit for Stable Plasma Power Delivery
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Solution Overview
Problem
Existing semiconductor fabrication processes, particularly plasma-based etching and plasma-enhanced atomic layer deposition, suffer from uncontrollable process variations due to variations in energy coupled to the fabrication chamber, leading to lower yields and increased costs.
Innovation Solution
An apparatus is provided with RF signal generators, electrically-small transmission lines, and a reactive circuit to transform impedance from a region of high sensitivity to a region of low sensitivity, avoiding resonant transmission lines and minimizing resistive loss, thereby maintaining consistent RF power delivery to fabrication stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional transmission lines are used to couple RF signals to the fabrication chamber, then impedance matching is achieved, but the system traverses resonant frequencies causing instability and process variations
Solution Approach 1:
The patent uses a dynamically adjustable impedance transformation network with variable capacitors and inductors that can be tuned in real-time to maintain optimal impedance matching without traversing resonant frequencies. This dynamic adjustment allows the system to adapt to changing plasma conditions while avoiding the instability caused by fixed transmission line resonances.
Solution Approach 2:
The invention changes the impedance parameters through a transformation network that converts the high impedance of the plasma load to a low impedance suitable for RF power coupling. By actively adjusting the transformation ratio and avoiding resonant frequencies, the system maintains stable power delivery despite variations in plasma impedance.
2Reliability
If electrically-small transmission lines are used to avoid resonance, then stability is improved, but RF power delivery efficiency decreases due to increased resistive loss
Solution Approach 1:
The patent introduces an impedance transformation network as an intermediary between the RF power source and the plasma load. This network acts as a mediator that converts the high impedance of the plasma to a low impedance suitable for efficient RF power coupling, thereby reducing resistive losses in the transmission line while maintaining stable power delivery.
Solution Approach 2:
By transforming the impedance parameters at the source end rather than relying on long transmission lines, the system reduces the electrical length of the transmission line and consequently the resistive losses. The impedance transformation network enables efficient power transfer by matching the source impedance to the transformed load impedance.
3Manufacturing precision
If impedance transformation is implemented to maintain consistent RF power delivery, then process control is improved, but device complexity increases due to additional reactive circuits
Solution Approach 1:
The impedance transformation network is designed to perform multiple functions: impedance matching, power optimization, and process stabilization. By consolidating these functions into a single integrated system, the patent reduces the overall complexity compared to using separate systems for each function while maintaining improved plasma process uniformity.
Solution Approach 2:
The system dynamically adjusts impedance transformation parameters to maintain consistent RF power delivery across varying plasma conditions. This parameter control enables precise manipulation of plasma properties such as density and temperature, thereby improving manufacturing precision without requiring overly complex circuit configurations.
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 allows for dynamic impedance matching, reducing reflections and maintaining consistent RF power delivery, even with varying loads, thus improving process control and reducing anomalies like arcing and deposition imbalances.
Implementation Method 1
a reactive circuit to transform impedance of each of the electrically-small transmission line from a region having a first impedance-sensitivity to a region having a second impedance-sensitivity
Implementation Method 2
one or more radiofrequency (RF) signal generators, one or more electrically-small transmission lines to couple signals from the one or more of RF signal generators to the fabrication chamber
Implementation Method 3
Impedance transformation in radio-frequency-assisted plasma generation
Data Source
AI summary
An apparatus for providing signals to a device may include one or more radiofrequency signal generators, and electrically-small transmission line, which couples signals from the one or more RF signal generators to the fabrication chamber. The apparatus may additionally include a reactive circuit to transform impedance of the electrically-small transmission line from a region of relatively high impedance-sensitivity to region of relatively low impedance-sensitivity.