Microwave RF Power Delivery for Uniform Plasma Electrodes
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Solution Overview
Problem
In semiconductor fabrication systems, higher frequency RF sources used for creating higher density plasma result in non-uniform electric fields due to shorter wavelengths, leading to non-uniform film deposition or etching across wafer surfaces.
Innovation Solution
A system with a radio frequency (RF) source circuit and solid-state impedance matching circuits that output RF signals of at least 300 MHz, electronically altering impedance to match with a distributed electrode, thereby improving electric field uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the frequency of the RF source is increased to create higher density plasma, then productivity is improved, but the electric field uniformity deteriorates due to shorter wavelengths
Solution Approach 1:
The patent divides the single RF source into multiple RF sources (e.g., four RF sources for a 300mm wafer), with each RF source connected to a separate electrode segment. This segmentation allows independent control of each electrode segment, enabling uniform plasma density across the entire wafer surface while maintaining high frequency operation for productivity.
Solution Approach 2:
The patent applies different RF power levels to different electrode segments based on local requirements. By adjusting the power delivered to each electrode segment independently, the system achieves uniform electric field distribution across the wafer surface, compensating for the non-uniformity caused by short wavelengths at high frequencies.
2Loss of time
If the frequency of the RF source is increased, then deposition and etch times are reduced, but the wavelength becomes comparable to chamber dimensions causing non-uniform electric field
Solution Approach 1:
The patent segments the electrode structure into multiple independently controlled sections, each fed by RF sources operating at high frequencies (e.g., 2.45 GHz). This allows the system to maintain the time-saving benefits of high-frequency operation while achieving uniform electric field distribution through localized control of each segment.
Solution Approach 2:
The patent employs dynamic control of RF power delivery to each electrode segment, adjusting power levels in real-time to maintain uniform electric field distribution. This dynamic adjustment compensates for the non-uniformity inherent in high-frequency operation, enabling both fast processing and uniform results.
3Device complexity
If a single RF source is used for simplicity, then device complexity is reduced, but electric field uniformity over the electrode deteriorates
Solution Approach 1:
The patent uses multiple RF sources connected to multiple electrode segments, with each segment independently controllable. This segmentation approach achieves uniform electric field distribution across the electrode surface, overcoming the limitations of single-source systems while maintaining manageable system complexity through modular architecture.
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 enhances the uniformity of the electric field on the distributed electrode, allowing for more efficient film deposition and etching processes even with higher frequency RF sources, reducing deposition and etch times.
Implementation Method 1
a solid-state impedance matching circuit operably coupled to the RF source circuit output and configured to receive the RF source signal output by the RF source circuit output; and electronically alter its impedance to enable an impedance match between the RF source circuit output and a load
Implementation Method 2
an RF source circuit comprising at least one RF generator and multiple RF source circuit outputs, each RF source circuit output outputting an RF source signal having a frequency of at least 300 MHz
Implementation Method 3
In a semiconductor fabrication system, one approach for reducing film deposition or etch times is to use a higher density plasma (HDP). One method for creating HDP is to increase the frequency of the RF source
Data Source
AI summary
In one embodiment, the present disclosure is directed to a system for controlling microwave power delivered to a distributed electrode to improve the uniformity of an electric field on the distributed electrode. The system includes an RF source circuit comprising at least one RF generator and multiple RF source circuit outputs, each RF source circuit output outputting an RF source signal having a frequency of at least 300 MHz. For each of the RF source circuit outputs, a solid-state impedance matching circuit is operably coupled to the RF source circuit output and configured to receive the RF source signal output by the RF source circuit output. For each of the matching circuits, a system output is operably coupled to the matching circuit and configured to output the RF source signal to a distributed electrode of the load.