RF Signal Measurement for Multi-Station Plasma Chamber Power Control
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Solution Overview
Problem
In semiconductor fabrication, variations in RF signal parameters lead to inconsistent deposition and etch rates, causing performance issues in integrated circuit devices due to inadequate monitoring and control of RF power in multi-station fabrication chambers, resulting in defects and reduced yields.
Innovation Solution
An apparatus that estimates RF signal parameters by using voltage and current sensors, analog-to-digital converters, and processors to transform signals into frequency domain representations, allowing for precise control of RF power delivery and minimizing power reflections, without relying on voltage division, peak detection, or buffer amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage division, peak detection, or buffer amplifiers are used to measure RF power, then measurement can be performed, but measurement precision and reliability are insufficient leading to process variations
Solution Approach 1:
The patent replaces traditional electronic measurement methods (voltage division, peak detection, buffer amplifiers) with a direct digital measurement approach. Voltage and current sensors convert RF signals to baseband signals, which are then directly digitized by high-speed analog-to-digital converters. This substitution of measurement methodology eliminates the precision limitations and reliability issues of traditional analog measurement chains, enabling accurate real-time RF power measurement for plasma process control.
2Productivity
If RF power is not accurately monitored and controlled, then fabrication can proceed, but deposition and etch rates become inconsistent causing performance issues
Solution Approach 1:
The patent implements a closed-loop feedback control system for RF power in plasma processes. High-speed analog-to-digital converters capture voltage and current waveforms in real-time, and processors calculate instantaneous RF power delivery to the plasma. This feedback information is used to dynamically adjust RF power levels, ensuring consistent deposition and etch rates across wafers while maintaining high fabrication throughput. The system monitors and controls RF power parameters including forward power, reflected power, and power delivery to the plasma.
3Device complexity
If traditional measurement methods are used, then device complexity is reduced, but the ability to make fine adjustments to process variables is lost
Solution Approach 1:
The patent enables dynamic control of multiple RF power parameters by directly measuring voltage and current waveforms and calculating instantaneous power delivery. The system can independently control and monitor forward power, reflected power, impedance, and power delivery to the plasma. This parameter-level control capability allows fine adjustments to process variables for optimal deposition and etch rates, while the digital measurement approach manages complexity through software-based signal processing rather than complex analog circuitry.
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 process uniformity and repeatability, reduces defect ratios, and improves the quality and yield of integrated circuit devices by accurately measuring and controlling RF power in real-time, preventing plasma extinguishing and maintaining optimal plasma conditions across all stations.
Implementation Method 1
the voltage sensor of the apparatus includes a capacitive voltage sensor
Implementation Method 2
the current sensor includes an inductive current transformer
Data Source
AI summary
An apparatus to estimate parameters of a radio frequency (RF) signal may include a voltage sensor configured to provide an indication of a voltage of the RF signal as well as a current sensor configured to provide an indication of current conducted by the RF signal. The apparatus may additionally include an analog-to-digital conversion module coupled to an output port of the voltage sensor and the current sensor, wherein the analog-to-digital converter is configured to provide digital representations of an instantaneous voltage and an instantaneous current of the RF signal. The apparatus may additionally include one or more processors configured to transform the digital representations of the instantaneous voltage and current into frequency domain representations of a complex voltage and complex current.