Adaptive Impedance Matching Design Of MBE Gas Source Furnace

In recent years,the worldwide competition for high-end technology has become more intense,and the necessity of the development of the semiconductor industry has gradually come to the fore.As the foundation of the semiconductor field,upstream semiconductor equipment in China started late and has a significant gap with the foreign leading level,and still needs to rely on imported foreign equipment to realize the production of most semiconductor products.Molecular beam epitaxy(MBE)equipment is the core equipment for the production of third-generation semiconductors,and the plasma source can be used as a gas source furnace on MBE equipment.This paper has conducted a understanding of the working mode of the plasma source,and based on this,a key technology in its working processimpedance matching is studied,and a technical solution that can realize adaptive impedance matching is proposed.Firstly,an equivalent model of the plasma source is constructed,and its equivalent impedance characteristics are obtained based on the electromagnetic simulation software CST;Then the importance of impedance matching is introduced,and the concept of Smith's circle diagram is introduced at the same time,and finally the L-shaped impedance matching network is selected as the impedance matching network of this device with the combination of the impedance change characteristics with the Smith Chart.Next,Smith V3.10 software is used to design the parameters of the components in the matching network;The vector voltammetry method is selected to monitor the overall reflection coefficient,the Roche coil is selected to extract the current signal,and the voltage signal is extracted from the voltage divider capacitor,and the parameters of the Roche coil and voltage divider capacitor is determined according to the current and voltage variation law during the operation.Then,the AD8302 is selected to process the signals of Roche coil and voltage divider capacitor,and output the amplitude ratio and phase difference between them;The STM32F429 IG is selected as the central control unit to calculate the AD8302 signals and then control the operation of the adjustment devices;The dual-output 42-type stepper motor is selected as the adjustment device to change the capacitance value and realize the monitoring of capacitance value;According to the designed adaptive impedance matching device,a direct solution method based on this device is proposed,which has a shorter adjustment time than other matching algorithms;Finally,some structures of the device are tested and verified,and the results show that all these structures can meet the design requirements and realize their respective functions.