Shibaura Institute of Technology
doctoral degree thesis
High frequency inverter for plasma generation equipment,
and research on high frequency matching devices.
March 2017 芝 浦 工 業 大 学
博 士 学 位 論 文
プラズマ生成装置の高周波インバータ、
および高周波整合器に関する研究
平成 29 年3 月
Overview
This paper is concerned with high-frequency plasma generation equipment for functional devices, semiconductor and liquid crystal manufacturing equipment, and aims to reduce power loss in high-frequency inverters, improve power conversion efficiency, and wide-range impedance matching of high-frequency matching boxes using high-frequency transformers. This is a summary of research results regarding.
Thin film formation using high-frequency plasma, such as plasma chemical vapor deposition (Plasma CVD), is widely used in the production of semiconductors, liquid crystals, and solar cells. In recent years, the range of applications has expanded to include thin film coatings for industrial purposes. Furthermore, as a pretreatment for a physical vapor deposition (PVD) process, high-frequency plasma treatment using high-frequency waves is widely used to remove a natural oxide film (pre-clean).
Conventionally, the mainstream of photoresist stripping treatments has been treatments that do not involve physical reactions, such as liquid etching treatment (wet etching) using acidic or alkaline solutions. In recent years, dry etching, which uses high-frequency plasma to etch materials with reactive gases, etching gases, ions, and radicals, has become mainstream in semiconductors, liquid crystals, and manufacturing equipment. High-frequency plasma technology is becoming increasingly important in the research and development of functional devices.
Conventionally, high-frequency inverters with a frequency of 13.56 MHz and a high-frequency output of 1 kW, which are often used in semiconductor manufacturing equipment, have a low high-frequency power conversion efficiency of about 50%, and about 1 kW of power loss is converted into heat. To dissipate 1 kW of heat, a water-cooled heat exchanger and auxiliary equipment were required, which required 200 liters of cooling water per hour. There were also problems from the environmental standpoint of cooling water and ancillary equipment, energy consumption, and economics.
In this study, we focused on high-frequency output transformers with the aim of reducing high-frequency power loss and improving power conversion efficiency. Conventionally, a high-frequency output of 1 kW was obtained using four output transformers, but in this research, we investigated a high-efficiency, high-frequency output transformer, and a circuit configuration that achieves a high-frequency output of 1 kW.
By using a single high-frequency inverter with a high-frequency output of 1 kW, it is possible to
The high frequency output synthesizer used in the frequency inverter is no longer required. Therefore, we investigated ways to reduce power loss in high-frequency output combiners.
To create a single high-frequency output transformer, four MOS-FETs must be connected in parallel. We investigated a push-pull type high-frequency inverter with four MOS-FETs connected in parallel using an axial printed circuit board (PCB).
We also investigated power loss and temperature at high frequencies in high-frequency output transformers and high-frequency output combiners, which are important in realizing high-efficiency, high-frequency inverters. Furthermore, we evaluated and investigated the power loss and temperature at high frequencies of the high frequency ferrite core that constitutes the high frequency output transformer.
Conventionally, in an ICP dry etching system using an L-type high-frequency matching box used in inductively coupled plasma (ICP), the chamber pressure used for high-frequency plasma generation is a low pressure of about 0.1 to 13 Pa, and a pressure of 1011 cm-3 or more is used for generating high-frequency plasma. High density plasma can be obtained. ICP high-frequency plasma is currently the mainstream etching method in semiconductor etching processes because high-density plasma can be obtained without using an electromagnetic coil.
In the production of functional devices, photocurable resin (photoresist) is used.
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