Instantaneous RF Power Measurement in Plasma Chambers
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Solution Overview
Problem
Current semiconductor chip fabrication processes face challenges in accurately monitoring and controlling the characteristics of plasma generated for surface modification, etching, and deposition, particularly due to the complexity of RF power distribution across multiple plasma processing chambers.
Innovation Solution
A system comprising RF power sources, voltage sensors, current sensors, and analog multiplier modules is used to measure and calculate instantaneous RF power in each plasma processing chamber, allowing for precise control and distribution of RF power without requiring phase measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional RF power measurement methods are used in multi-chamber plasma processing systems, then RF power can be distributed to multiple chambers, but measurement precision and control accuracy deteriorate due to phase shift complexities and calibration requirements
Solution Approach 1:
The system divides the multi-chamber plasma processing system into independent measurement channels, with each chamber having its own voltage sensor, current sensor, and analog multiplier module. This segmentation allows each chamber's RF power to be measured independently without interference from other chambers, eliminating the need for complex phase measurements and calibrations across the entire system.
Solution Approach 2:
The patent replaces complex electronic phase measurement and calibration systems with a direct instantaneous power calculation approach. By using analog multiplier modules to directly multiply voltage and current signals in the time domain, the system eliminates the need for phase angle measurements and complex calibration procedures, achieving accurate RF power measurement through a simpler method.
2Reliability
If instantaneous RF power measurement is implemented across multiple plasma processing chambers, then process control improves, but device complexity increases due to multiple sensors and multiplier modules
Solution Approach 1:
The measurement system is segmented into independent modular units, with each plasma processing chamber having its own complete measurement chain (voltage sensor, current sensor, analog multiplier). This modular segmentation allows the system to achieve reliable instantaneous power measurement for process control while keeping each measurement unit simple and independent, making the overall system manageable despite serving multiple chambers.
3Measurement precision
If phase measurement methods are used for RF power calculation, then theoretical accuracy can be achieved, but ease of operation deteriorates due to calibration requirements and error sources
Solution Approach 1:
The patent substitutes the theoretical but operationally complex phase measurement method with a practical instantaneous multiplication method. By directly multiplying voltage and current signals in the time domain using analog multiplier modules, the system achieves accurate RF power measurement without requiring phase angle measurements, calibration procedures, or complex error corrections, greatly simplifying operation while maintaining accuracy.
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 enables accurate and cost-effective measurement of RF power delivered to each chamber, improving process control and efficiency by directly measuring instantaneous RF power, reducing errors associated with phase shifts and calibration complexities.
Implementation Method 1
Each of the plurality of voltage sensors is configured to output a signal indicating an instantaneous electrical voltage present on the RF power input line to which it is connected
Implementation Method 2
Each of the plurality of current sensors is configured to output a signal indicating an instantaneous electrical current present on the RF power input line to which it is connected
Implementation Method 3
Each of the plurality of analog multiplier modules is configured to generate an output signal representing a product of its first and second input signals. The output signal of a given one of the plurality of analog multiplier modules indicates an instantaneous RF power present on the RF power input line
Implementation Method 4
RF power is transmitted to generate a plasma within the plasma processing chamber
Implementation Method 5
The plasma is often generated by applying radiofrequency (RF) power to a process gas in a controlled environment, such that the process gas becomes energized and transforms into the desired plasma
Data Source
AI summary
Each of multiple plasma processing chambers has an RF power input line connected to receive RF power from a common RF power source. An RF control module is connected to distribute RF power from the common RF power source to the RF power input lines of the multiple chambers. A voltage sensor and a current sensor are connected to a corresponding RF power input line. Each voltage sensor measures an instantaneous electrical voltage present on its RF power input line. Each current sensor measures an instantaneous electrical current present on its RF power input line. An analog multiplier module is connected to receive as inputs the instantaneous electrical voltage from its corresponding voltage sensor and the instantaneous electrical current from its corresponding current sensor. Each analog multiplier module generates an output signal that indicates an instantaneous RF power present on the corresponding RF power input line of the corresponding chamber.