Special gases are essential silicon-based support source materials in fields such as optoelectronics and microelectronics, especially in the manufacturing of ultra large scale integrated circuits, liquid crystal display devices, amorphous silicon thin-film solar cells, semiconductor light-emitting devices, and semiconductor materials. Its purity and cleanliness directly affect the quality, integration, specific technical indicators, and yield of optoelectronic and microelectronic components, and fundamentally constrain the accuracy and precision of circuits and devices.
Semiconductor lighting is an emerging industry, and with the expansion of the compound semiconductor market, the demand for specialty gases is showing greater growth. Epitaxial growth requires a large amount of ultra pure sources and process gases. At present, the compound semiconductor markets in Taiwan and Japan have a relatively high market share. In recent years, China and South Korea have shown strong development momentum, and the market share in North America and Europe has also increased. The special gases used in semiconductor technology have a wide variety of types, strict quality requirements, and technical and safety requirements for production, filling, transportation, and storage. In addition, factors such as economic scale require accumulation from multiple aspects to achieve large-scale production. Therefore, the current situation in China is characterized by a large market and limited supply capacity.
The semiconductor industry uses a wide variety of gases with high quality requirements and low usage, most of which are toxic or corrosive gases. There are over a hundred varieties. The classification of special gas applications in the semiconductor industry mainly includes:
1. Silicon based gases: Silanes containing silicon, such as silane, dichlorosilane, disilane, etc.
2. Doping gas: a gas containing three or five groups of atoms such as boron, phosphorus, arsenic, etc., such as boron trichloride, boron trifluoride, phosphine, arsine, etc.
3. Etching cleaning gas: mainly containing halides and halogenated carbon compounds, such as chlorine gas, nitrogen trifluoride, hydrogen bromide, carbon tetrafluoride, hexafluoroethane, etc.
4. Reactive gases: mainly composed of carbon and nitrogen oxides, such as carbon dioxide, ammonia, nitrous oxide, etc.
5. Metal vapor deposition gas: containing halogenated metals and organic alkane metals such as tungsten hexafluoride, trimethyl gallium, etc.
In the LED industry chain, epitaxial technology, equipment, and materials are the key to epitaxial wafer manufacturing technology. The current MOCVD process has become the fundamental technology for manufacturing the vast majority of optoelectronic materials. The ultra pure specialty gases required for epitaxial technology include high-purity arsine, high-purity phosphine, and high-purity ammonia. Silane N-type doping is used in gallium arsenide production, while hydrogen chloride and chlorine gas are often used as etching gases, and argon, hydrogen, and nitrogen are necessary carrier gases. The organic sources required for simultaneous epitaxial growth are mainly trimethyl gallium, trimethyl indium, trimethyl aluminum, diethyl zinc, dimethyl zinc, ferrocene, etc. The development of existing technology has increasingly high quality requirements for these products.
In the production process of semiconductor compounds, in addition to pure specialty materials, some mixed gases are also required, mainly including SiH4/H2. SiH4/N2 as the film-forming source. Although the amount used is not large, it requires extremely high product quality. The dew point of the mixed gas should be below -95 ℃ to ensure the yield of epitaxial wafer growth.
The expansion of the compound semiconductor industry has driven the rapid growth of the raw material market, including demand for wafers, substrates, etchants, process gases, organic metal compounds, testing and packaging materials, etc., increasing at a rate of approximately 21% annually. Process gases (arsine, phosphine, ammonia, argon, hydrogen, nitrogen, hydrogen chloride, chlorine, etc.) account for 8% of the overall raw material consumption.
