The localization of electronic special gas meets the historic opportunity

Overview of electronic gases

Electronic chemicals are the key basic chemical materials in the electronic industry, and the development of the electronic industry requires electronic chemicals to develop simultaneously with it and constantly update to meet the needs of its continuous innovation in technology. Especially in the fine processing of integrated circuits (IC), the key electronic chemicals required mainly include: photoresist (also known as photoresist), ultra-clean and high-purity reagents (also known as process chemicals), electronic special gases and epoxy plastic sealing materials, in which ultra-clean and high-purity reagents, photoresist, electronic special gases are used for the pre-process, and epoxy plastic sealing materials are used for the post-process. These microelectronic chemical materials account for about 20% of the total cost of IC materials, of which ultra-clean high-purity reagents account for about 5%, photoresist accounts for about 4%, and electronic special gases account for about 5%-6%.

1. Definition of electron gas

Industrial gases can be roughly divided into two categories, namely general industrial gases and special gases. General industrial gases refer to ordinary grade oxygen and nitrogen produced by air separation equipment, and other types of gases of ordinary purity produced by coke oven gas separation or electrolysis. General industrial gases require large production, but the purity of the gas is not high. Special gases are gases that are different from general gases and are a general concept. It is produced and used in strict accordance with certain specifications in terms of purity, variety and performance. It is generally believed that special gases are composed of electronic gases, high-purity petrochemical gases and standard mixed gases. In addition, in the semiconductor manufacturing industry, the gas can also be divided into bulk gas and electronic gas, bulk gas refers to the centralized supply and large amount of gas, such as N2, H2, O2, Ar, He, etc. Electronic gas is mainly a variety of chemical gases used in each process of semiconductor manufacturing, such as epitaxial growth, ion implantation, doping, etching cleaning, and mask film generation, such as high-purity SiH4, PH3, AsH3, B2H6, N2O, NH3, SF6, NF3, CF4, BCI3, BF3, HCI, CI2, etc. Also known as electronic special gas.

2, industrial gas development history

The first stage: industrial gases begin to enter the commercial sector. At the end of the 18th century, scientists separated nitrogen and oxygen from the air by chemical methods, laying the foundation for the industrial gas industry. In the early days of the industry, oxygen was mainly used in the medical field, and began to enter commercial uses such as welding at the end of the 19th century. At the same time, acetylene was discovered and gradually became a commonly used welding gas, and then acetylene was found to be soluble in acetone, which made the long-distance transportation of acetylene possible, further promoting the commercial application of acetylene.

The second stage: the industrial gas industry is maturing. The invention and application of fractionation process has greatly reduced the production cost of industrial gases and accelerated the industrialization process of industrial gases. In the mid-20th century, two world wars and the use of oxygen and acetylene torch cutting technology strongly promoted the growth of industrial gas demand. At the same time, in order to reduce the content of carbon and phosphorus and improve the quality of steel products, steel companies gave up the early air injection method and switched to oxygen injection method, and the adoption of the new method increased the global oxygen production by 10 times in 1965 compared with 1960. In addition, nitrogen is also used in large quantities as an inert "covering agent", which promotes the large-scale construction of gas production equipment.

The third stage: The industrial gas industry continues to grow. The rise of the electronics industry in the 1980s boosted demand for specialty gases. Increasing consumption in traditional markets such as metal prefabrication and production, coupled with the addition of new applications in end markets such as health care, electronics, beverages and food packaging, the gas industry continued to grow in the 1990s. The energy sector has been the biggest driver of the gas industry over the past few years. Gas is widely used as an energy source in many industries, which makes gas demand continue to strengthen in the early 21st century.

3, electronic gas classification

Electronic special gases are indispensable raw materials for the production of ultra-large scale integrated circuits, flat panel display devices, compound semiconductor devices, solar cells, optical fibers and other electronic industries. They are mainly used in thin film, etching, doping, vapor deposition, diffusion and other processes. The electronic industry services a wide variety of electronic gas, a variety of uses, its classification is also more complex. Generally, it can be classified according to the amount of electronic gas, and it can also be classified according to the use of electronic gas. Many types of gases are used for manufacturing purposes. Generally, we are distinguished by gas characteristics, which can be divided into two categories: special gas and general gas. The former is a small amount of gas, such as SiH4, NF3, etc., the latter is a large amount of gas, such as N2, CDA (dry compressed air). In semiconductor manufacturing, it is necessary to provide a variety of high-purity general gases for pneumatic equipment power, chemical transport pressure media or as an inert environment, or to participate in the reaction to remove impurities and other different functions.

According to the different uses of electron gas, electron gas can be divided into more than ten categories, such as epitaxial crystal growth gas, thermal oxidation gas, epitaxial gas, doping gas, diffusion gas, chemical vapor deposition gas, injection gas, ion injection gas, plasma etching gas, carrier gas, purge gas, lithography gas, annealing gas, welding gas, sintering gas and balance gas. Table 2 lists examples of electronic gases used in the electronics industry and semiconductor device fabrication processes.

Second, the introduction of important electronic gases

1, Silane (SiH4) : the best silicon source material for epitaxial crystal growth

Silane melting point -185°C, boiling point -112°C, spontaneous combustion in the air, and air can form an explosive mixture, the explosion limit in the air is 0.8% to 98.0% volume fraction; Halogens or heavy metal halides can react violently at room temperature. Silane is heated to 400 degrees Celsius and begins to decompose into amorphous silicon and hydrogen, and more than 600 degrees Celsius decompose into crystalline silicon, and the semiconductor industry mainly uses this method to produce polysilicon. Silane is very toxic, can strongly stimulate the human respiratory tract, the victim may have headaches and nausea and other symptoms, inhalation of large amounts will cause physiological changes in the respiratory and lymphatic system. Silane is the most widely used in electronic gases, the most influential gas variety, because silane flammable, explosive, high purity requirements, technical difficulty is very difficult, so silane is also one of the important signs of a country's gas strength. As a gas source that provides silicon components, monosilane can be used to manufacture high-purity polysilicon, monocrystalline silicon, microcrystalline silicon, amorphous silicon, silicon nitride and other metal silicides. Because of its high purity and fine control, it has become an important electronic special gas that cannot be replaced by many other silicon sources. Mono-silane is widely used in the microelectronics and optoelectronics industry, for the manufacture of solar cells, flat panel displays, etc., and is the world's only large-scale production of granular high-purity silicon intermediates. Silane manufacturing can be divided into magnesium silicide process, lithium aluminum hydride process and UCC process (non-homogenization process).

2, Arsenane (AsH3) : a unique arsenic source compound, due to highly toxic domestic production is difficult

AsH3 is a colorless, highly toxic, flammable gas at room temperature and atmospheric pressure, with a garlic-like odor. Mixed with air to form a combustible mixture. Arsenane is slightly soluble in water and organic solvents, and is easy to react with potassium permanganate, bromine and sodium hypochlorite to form arsenic compounds. Arsenane is stable at room temperature and begins to decompose at 230-240°C. Arsenane is a hemolytic poison that can cause neurotoxicity. AsH3 is an indispensable basic material for GaAs, GaAsP growth, N-type silicon epitaxy, diffusion, ion implantation doping, etc. Due to its highly toxic, high purity requirements, synthesis, purification difficulty and other factors, the number of countries that can manufacture AsH3 is not large, and due to the extreme toxicity of AsH3, it is very troublesome to import in today's international background.

AsH3 is an important material for the manufacture of gallium arsenide semiconductor compound, so far there is no substitute for AsH3. Arsenane is a popular product in China, although many units claim to have arsenane production technology, but arsenane and arsenic-containing compounds are serious drugs, so it is difficult to meet the national series of production permits. In the current domestic security background, few companies are willing to take risks to carry out such work. The Tianjin explosion in 2015 increased the difficulty of the localization of China's AsH3. From the technical point of view, there are many similarities between the synthesis of arsenane and the synthesis of phosphorane, the only difference is the toxicity of the two. In 2018, the purity of high-purity phosphoane and arsenane produced by Quanjiao Nanda Optoelectronics, a holding subsidiary of Nanda Optoelectronics, reached 6N level. Relying on the parent company's mature sales channels and excellent technical support, the products have achieved major market shares in the LED industry and contributed to better sales performance.

3, nitrous oxide (N2O) : dielectric film process gas, the current domestic production capacity is about to grow

Nitrous oxide is a colorless sweet gas that can support combustion under certain conditions, but is stable at room temperature, has a slight anesthetic effect, and can cause people to laugh, commonly known as laughing gas. As an electronic gas, nitrous oxide is mainly used in the dielectric film process for the development and production of semiconductor optoelectronic devices, and is an irreplaceable key point gas that directly affects the quality of optoelectronic devices. High purity nitrous oxide is an important raw material for PECVD deposition of SiO2 film, masking film, passivation film, anti-reflection and anti-reflection film of devices. The purity of N2O directly affects the purity of SiO2 film. If the impurity content is high, the deposited SiO2 film has many particles and is not bright, resulting in uneven surface refractive index and other phenomena, which is not conducive to the process of lithography. If the trace water content in N2O is high, it can cause the hydrogen content of SiO2 film to be large, and the compactness can not meet the requirements, resulting in unstable working state of the device and weak anti-electromagnetic radiation ability. Therefore, in order to ensure the quality and reliability of photoelectric device products, the purity of nitrous oxide must be above 5N.

4, ammonia (NH3) : the film forming gas of nitriding film in the electronics industry, is an important "nitrogen" source of chemical vapor deposition

In the microelectronics industry, high purity ammonia is one of the indispensable raw materials. It is mainly used in the growth process of silicon nitride mask in semiconductor device and integrated circuit manufacturing and nitrogen doped process in manufacturing gallium phosphide green luminous materials. When the silicon wafer is deposited and grows the silicon nitride mask, even if the high purity ammonia contains only 50 parts per million of trace water, only silicon oxide is obtained, rather than the required silicon nitride. Also containing trace oxygen (greater than 3 parts per million) of ammonia for gallium phosphide nitrogen will bring deep level of oxygen impurities, so that the diode emitted green light (wavelength 500nm) doped with infrared light (wavelength 900nm) and red light (wavelength 700nm), high purity ammonia in the oil and other impurities on the semiconductor device is also quite large harm.

5, nitrogen trifluoride (NF3) : gas cleaning agent, at present, the domestic technology monopoly has been broken

The melting point of nitrogen trifluoride is -208.5°C, the boiling point is -129°C, and the relative density of the liquid at the boiling point is 1.89. NF3 is the most stable of nitrogen trihalides, but it explodes violently when mixed with water, hydrogen, ammonia, carbon monoxide or hydrogen sulfide. High purity NF3 is almost odorless, it is a thermodynamically stable oxidizing agent, at about 350°C can decompose into nitrogen difluoride and fluorine gas, can react with many elements at high temperatures, can be used as a free radical supply source. Perfluorocarbons (PFCS), which are harmful to the environment as industrial gas cleaners for semiconductors, have been gradually replaced by NF3 in recent years. Using a CVD box that is more stable and easier to handle than F2, it can reduce pollutant emissions by about 90% compared to PFC, and can significantly improve the cleaning speed, which can increase the cleaning equipment capacity by about 30%. NF3 is also an excellent plasma etching gas in the microelectronics industry, etching silicon and silicon nitride, has a higher etching rate and selectivity, and no pollution to the surface, especially in less than 1.5μm of integrated circuit materials can be heavy, NF3 has a very good moment rate and selectivity, leaving no residue on the etched surface.

3. Current status of electronic gases in China

In semiconductor materials, electronic gases are the second largest market demand after large silicon wafers, accounting for 14% of the semiconductor materials market in 2016. With the development of the semiconductor industry, the electronic gas market has also grown. The global electronic specialty gases market was $3.89 billion in 2016 and grew to $4.512 billion in 2018, an increase of 15.93% from 2016. With the transfer of the global semiconductor industry chain to the domestic, the domestic electronic gas market has accelerated significantly, far higher than the global growth rate. According to the statistics of the China Semiconductor Industry Association, from 2010 to 2018, the market size of China's electronic special gas industry has maintained a rapid development trend, reaching 12.156 billion yuan in 2018, an increase of 11.19% compared with 2017.

In recent years, the domestic semiconductor market has developed rapidly, and the production capacity under construction and planned for future construction has provided a broad space for electronic gases. With the development of semiconductor integrated circuit technology, the purity and quality of electronic gases are increasingly required. Every order of magnitude increase in the purity of electronic gases will have a huge impact on the downstream integrated circuit industry. In 2014, the state issued the "National Integrated Circuit Industry Development and Promotion Outline" and established the integrated circuit industry investment fund, according to the plan, the average annual growth rate of China's integrated circuit sales will remain at about 20%, is expected to reach 870 billion yuan in 2020. If the domestic electronic gas for semiconductor integrated circuits maintains the same stable growth rate, its market size in 2020 will increase by 44% on the basis of 2018.

1, the industry concentration is high, and local enterprises are gradually rising

After years of development and mergers and acquisitions, the global industrial gas market has formed a market pattern in which a few gas producers occupy the majority share of the global market. According to SAI Corporation statistics: In the global industrial gas market in 2013, the top four manufacturers in the global industrial gas market, The top four manufacturers - France's Air Liquide Group (ALAL), Germany's Linde Group (Linde), the United States PRAXAIR Group (PRAXAIR) and the United States Air Chemical Products group (AirProducts) together account for 75% of the market share, the market is highly concentrated. On October 23, 2018, Linde Group announced the merger of equals with Praxair Group of the United States to become the world's largest industrial gas business supplier business supplier, and in the same year, the three gas giants (Linde, liquefied Air, air Chemicals) accounted for 76.71% of the global industrial gas outsourcing market. Compared with traditional bulk gases, the electronic gas industry has a high market concentration due to high technical barriers. In the global semiconductor electronic gas market in 2018, five major companies such as Air Chemical of the United States, Praxair of the United States, Linde Group of Germany, Air Liquide of France and Dayo Nippon Acid Co., LTD., controlled more than 90% of the global market share, forming an oligopoly situation. In the domestic market, several leading overseas enterprises also control 85% of the share, China's electronic gas is subject to the situation is very serious.

2. Technology is difficult to overcome in the short term

One of the main reasons for the wide market share of domestic and foreign enterprises is the technical gap that is difficult to make up in a short period of time. The production of special gas is a systematic engineering, which involves the deep purification technology of gas, the analysis and detection technology of trace impurities, the inner surface treatment technology of gas cylinder, and the detoxification treatment technology of toxic exhaust. 

There are many reasons that e-gas technology can't overcome:

First, the deep purification technology is difficult. According to Jing Song, a researcher at the Institute of Semiconductor Materials, Zhejiang University, taking silane as an example, there is a long way to purify its purity from 4N to 6N, in addition to solving the purification problem of ordinary gaseous impurities, but also to purify metal elements to 10-9 and 10-12 levels, to develop new processes or new adsorbents, catalysts.

Second, the storage and transportation of packaging boxes can not keep up. The production and application of ultra-high purity gas require the use of high-quality gas packaging storage and transportation containers, corresponding gas transmission lines, valves and interfaces to avoid the occurrence of secondary pollution. Internationally renowned gas companies have independently developed cylinder and cylinder handling technologies suitable for contemporary electronic gas packaging storage and transportation. China has not carried out systematic research and development work in this area, and the gap with foreign countries is very large.

Third, the concept of analysis and inspection is backward. Foreign countries have developed systematic and complete analysis and testing methods and on-site analysis instruments, which have withdrawn a variety of analytical instruments for impurity components, particles and metal ions that are more harmful in electronic gases. However, under the guiding ideology of "the product is produced, not detected", China has not paid enough attention to the research and development of analytical detection technology in the field of electronic gas production and application. At present, the level of domestic analysis and testing technology is not in line with international standards.

3, domestic electronic gas is difficult to enter the integrated circuit and other fields

Although from the technical point of view, some domestic enterprises have basically had the ability to produce high-purity electronic gases, but they can not enter the integrated circuit and other fields for three main reasons:

First, the local electronic gas production and suppliers are small in scale, and can not provide users with a full range of services. Compared with international giants, domestic suppliers are generally small in size, and most of them occupy a limited market share through low-price competition. Fierce competition among local suppliers leads to rapid price decline, thin profits, and even losses.

Second, electronic gases, especially high-purity electronic gases, are important factors affecting the reliability and yield of electronic devices. With the rapid development of electronic information technology, the quality stability of electronic gas is more and more demanding. If an electronic gas product is validated in the IC manufacturing process, such purity and quality requirements are locked in. Chipmakers don't want to see any change in the quality of their products, and even a further increase in purity could create unexpected problems. Therefore, any change in the production process of electronic materials, including the replacement of raw material suppliers, changes in the production process, etc., must be notified in time to the chip manufacturer, and decide whether to re-verify according to the situation. Electronic gases produced by domestic enterprises have suffered many quality accidents, affecting the trust of chip manufacturers in local electronic products.

Third, the packaging, storage and transportation of domestic electronic gas products have failed to meet the requirements of the modern electronics industry. In order to save costs and compete at low prices, many enterprises have reduced requirements in packaging, storage and transportation, so there have been various problems.

4. Future development trend

The specialty gas market is growing rapidly. Under the new normal of the economy, more emphasis will be placed on the optimization and upgrading of the economic structure, and the contribution of integrated circuits, display panels, photovoltaic energy, optical fiber and cable, new energy vehicles, aerospace, environmental protection, medical and other industries to China's economic growth will become more prominent. As an indispensable key material for the development of the above industries, the market size of special gases will continue to maintain rapid development. According to Zhuochuang information statistics, 2010-2017 China's special gas market average growth rate of 15.48%, 2017 China's special gas market size of about 17.8 billion yuan, of which integrated circuits, display panels, photovoltaic energy, optical fiber and cable semiconductor field of special gas market size of about 10 billion yuan. At the same time, according to Zhuo Chuang Information, the growth rate of China's special gas market in 2018-2022 will still be as high as 15%, and the size of China's special gas market will reach 41.1 billion yuan by 2022. Special gases will inject new impetus into the development of emerging industries in China. In the world, the special gas also maintained a high growth rate, in 2017, the global special gas market reached 24.1 billion US dollars, an increase of 11.55% compared with 2016, the special gas market space is broad.

The localization of special gases is the general trend. Since the introduction of special gases into the Chinese market in the mid-1980s, China's special gas industry has undergone 30 years of development and precipitation. With the continuous accumulation of experience and technological progress, leading enterprises in the industry have achieved breakthroughs in some products, reached the international standard, and gradually realized import substitution, and the localization of special gases has objective conditions. At the demand level, in recent years, China has continuously built a number of 8-inch, 12-inch large-scale integrated circuit production lines, high-generation panel production lines, etc., in order to ensure stable supply, timely service, and cost control, there is an urgent need for the localization of special gases. In addition, in recent years, the state has issued guiding documents such as the "13th Five-Year Plan for the Development of National Strategic Emerging Industries" and the "New Materials Industry Guide", aiming to promote the localization of key materials, including special gases. Therefore, under the influence of multiple factors such as technological progress, demand pull and policy stimulus, the localization of special gases is imperative.