Electronic gases, important raw materials for the semiconductor industry

Introduction to Electronic Gases

Electronic specialty gases (referred to as electronic gases) are an important branch of specialty gases and are indispensable raw materials for the production of integrated circuits (IC), flat panel display devices (LCD, LED, OLED), solar cells, and other electronic industries.

In the semiconductor production industry, gases are typically divided into two categories: common gases and special gases. Common gases refer to those that are centrally supplied and used in large quantities, such as N2, H2, O2, Ar, He, etc. Special gases refer to the chemical gases used in semiconductor production processes, such as extension, ion implantation, doping, cleaning, and mask formation. These are the electronic gases in the gas category, such as high-purity SiH4, PH3, AsH3, B2H6, N2O, NH3, SF6, NF3, CF4, BCl3, BF3, HCl, Cl2, etc. In the IC production process, nearly 100 types of electronic gases are used, with about 30 commonly used in core processes. It is these gases that give silicon wafers semiconductor properties through different processes, determining the performance, integration, and yield of integrated circuits. Even a slight excess of a specific impurity can lead to serious quality defects, and in severe cases, the diffusion of unqualified gases can contaminate the entire production line, causing a complete shutdown. Therefore, electronic gases are key foundational materials in the electronic manufacturing process and are rightly called the "blood" of the electronics industry.

The raw materials for electronic gases mainly include air separation gases, low-purity raw gases produced during petrochemical and coal chemical production processes, waste gases, and other basic chemical raw materials. The main raw materials are widely sourced, with ample market supply, making it relatively easy to obtain them from related raw material suppliers. Large steel and fertilizer enterprises in China are generally equipped with air separation equipment, ensuring a large and stable supply of air separation gases. The consumption of raw gases for electronic specialty gases accounts for a small proportion of the output of petrochemical and coal chemical raw gases, and the stable petrochemical and basic chemical industries can provide sufficient raw materials for the electronic specialty gas industry. The "13th Five-Year Plan" further clarifies environmental protection and industrial waste gas emission targets, ensuring a more abundant supply from upstream industries. Gas containers, which can be used for a long time, account for a low proportion of electronic gas costs, and price fluctuations have little impact on the industry.

Classification and Applications of Electronic Gases

There are many types of electronic gases, widely used in electronic product manufacturing processes. Currently, there are more than 60 types of pure electronic gases and more than 80 types of mixed gases in common use. Electronic gases can be divided into three categories: pure gases, high-purity gases, and semiconductor special material gases. Special material gases are mainly used in processes such as epitaxy, doping, and etching; high-purity gases are mainly used as dilution and carrier gases.

Electronic gases are mainly used in semiconductors, flat panel displays, solar cells, and other fields, with a domestic market demand of 8 billion yuan. According to the China Industrial Gas Association, the domestic demand for electronic specialty gases reached 8 billion yuan in 2019, including 3.5 billion yuan for integrated circuits, 2.2 billion yuan for flat panel displays, and 800 million yuan for solar cells.

The manufacturing of integrated circuit chips requires the use of various electronic gases, including silicon-based gases such as silane, doping gases such as PH3, etching gases such as CF4, metal vapor deposition gases such as WF6, and other reaction and cleaning gases. In the preparation process of electronic-grade silicon, electronic gases such as SiHCl3 and SiCl4 are involved. In the chemical vapor deposition (CVD) process for forming films on silicon wafers, gases such as SiH4, SiCl4, and WF6 are mainly involved. In some wafer processes, gas etching, also known as dry etching, is used, involving electronic gases such as CF4, NF3, and HBr. These etching gases are used in relatively small quantities and need to work with inert gases such as Ar and N2 to achieve uniform etching. The doping process involves introducing the required impurities into specific semiconductor regions to change the electrical properties of the semiconductor, involving electronic gases such as B2H6 and BF3 (trivalent gases) and PH3 and AsH3 (pentavalent gases).

In the flat panel display industry, the main types of electronic gases used include silicon-based gases such as silane, doping gases such as PH3, and etching gases such as SF6. In the thin film process, SiO2, SiNx, and other films are deposited on glass substrates through chemical vapor deposition, using specialty gases such as SiH4, PH3, NH3, and NF3. In the dry etching process, selective corrosion of the substrate occurs in a plasma gas environment, typically using gases such as SF6, HCl, and Cl2.

Solar cells can be divided into crystalline silicon solar cells and thin-film solar cells. In the production of crystalline silicon solar cells, POCl3 and O2 are used in the diffusion process, SiH4 and NH3 are used in the plasma-enhanced chemical vapor deposition (PECVD) process for anti-reflection layers, and CF4 is used in the etching process. In thin-film solar cells, diethyl zinc (DEZn) and B2H6 are used in the deposition of transparent conductive films, and silane is used in the deposition of amorphous/microcrystalline silicon.

Application Fields of Electronic Gases

Semiconductor Industry—The Most Important Downstream Application of Electronic Gases

Gases are the second largest consumable in wafer manufacturing. According to 2018 sales data, silicon wafers, as the raw material for semiconductors, account for the largest proportion of manufacturing materials at 37%, with sales of $12.1 billion. Due to the many steps involved in the manufacturing process, the consumption of electronic gases is much higher than other materials, accounting for 13% with sales of $4.3 billion. Gases (including high-purity and mixed gases) are the most commonly used manufacturing materials in wafer manufacturing, and as a core raw material in semiconductor materials, their consumption cost is the highest after silicon wafers. They are often used in steps such as photolithography, etching, and CVD/PVD. Especially in the integrated circuit manufacturing process, high-purity bulk gases such as N2, H2, O2, Ar, and He are often used in high-temperature thermal annealing, protective gases, and cleaning gases. High-purity electronic specialty gases are used more in the manufacturing process, also known as electronic gases, such as chemical gases used in ion implantation, vapor deposition, cleaning, and mask formation, commonly including SiH4, PH3, AsH3, B2H6, N2O, NH3, SF6, NF3, CF4, BCl3, BF3, HCl, and Cl2. In the IC production process, nearly 100 types of electronic gases are used, with about 40-50 commonly used in core processes.

With the development of semiconductor integrated circuit technology, the purity and quality requirements for electronic gases are becoming increasingly stringent. Each order of magnitude increase in the purity of electronic gases has a significant impact on the downstream integrated circuit industry. In 2014, the state issued the "National Integrated Circuit Industry Development Promotion Outline" and established the Integrated Circuit Industry Investment Fund. According to the plan, the annual growth rate of China's integrated circuit sales will remain at around 20%, and it is expected to reach 870 billion yuan by 2020. If the electronic gases used in semiconductors maintain the same stable growth rate, the domestic semiconductor electronic gas market will double by 2020.

The proportion of the electronic gas market in mainland China is continuously increasing. According to data from the Forward Industry Research Institute, the market size of China's electronic specialty gases has been increasing, from $1.34 billion in 2014 to $2.004 billion in 2018, with the global proportion increasing from 38.5% to 44.4%. With the continuous increase in production capacity, the proportion will also increase. 2020-2022 is the peak period for the commissioning of wafer fabs in mainland China, with emerging wafer fabs such as Yangtze Memory and ChangXin Memory and established wafer fabs such as SMIC and Huahong in a period of capacity expansion, and intensive commissioning is expected in the next three years. Calculated in terms of 12-inch equivalent capacity, the mainland's production capacity in 2019 was 1.05 million wafers per month, and it is expected to increase to 2.01 million wafers per month by 2022. According to the construction speed and planning of domestic wafer fabs, the domestic electronic gas market in 2022 is expected to be twice that of 2019, and the electronic gas market is entering a period of rapid development. Based on the market space of $2 billion in 2019, it is expected that by 2022, the market space for electronic gases in mainland China will be close to $4 billion, achieving a doubling of the market size.

Electronic Gases for Flat Panel Displays—The Rapid Development of TFT-LCD Will Expand the Market Space for Electronic Gases

There are many types of flat panel displays, among which TFT-LCD has fast response time and high imaging quality, making it the most widely used LCD technology. The manufacturing process of TFT-LCD panels can be mainly divided into three steps: front-end array process, mid-end cell process, and back-end module assembly process. Electronic specialty gases are mainly used in the film formation and dry etching stages of the front-end array process, depositing SiNx non-metallic films and metal films such as gate electrodes, source-drain electrodes, and ITO on the substrate through multiple film formation processes. The TFT-LCD panel industry in mainland China is entering a golden era of development. In 2016, the global electronic gas market for TFT-LCD panels exceeded 6.6 billion yuan, and the domestic market reached 2.2 billion yuan. In recent years, global LCD panel production capacity has been continuously shifting from Japan, South Korea, and Taiwan to mainland China. With the slowdown in the construction of new LCD production lines in South Korea and Taiwan, domestic manufacturers such as BOE and CSOT have emerged. With the rapid growth in TFT-LCD market demand and the strong promotion of the flat panel display industry by central and local governments, large-scale, high-generation TFT-LCD panel projects are being invested and built everywhere, and major domestic manufacturers are still rapidly expanding production. Currently, the application of LCD panels is increasingly trending towards large size and high definition, and large-size LCD panels need to be cut through high-generation production lines. Domestic manufacturers such as BOE, CSOT, and HKC are laying out high-generation production lines, and the demand for electronic gases will also greatly increase.

Barriers in the Electronic Gas Industry

Electronic gases are widely used, with high technical requirements and stringent requirements for gas sources and supply systems, belonging to a typical technology-intensive industry. The most difficult industry barriers are reflected in two levels: 1. Technical barriers; 2. Qualification barriers.

1. Technical barriers. The technical barriers of electronic gases can be divided into gas purity barriers and gas precision barriers. In terms of gas purity, the purification of specialty gases is the main technical barrier in gas manufacturing. In ordinary industrial fields, the purity requirement for specialty gases is within 99.99%. However, in the electronic grade, especially in the field of semiconductor chip manufacturing, as chip manufacturing technology has developed to the nanometer level, the gas purity must also be at the ppt level or above. Excessive impurity content in the gas will seriously affect chip yield and reliability. The purity requirements for electronic gases are also becoming increasingly stringent, often requiring 6N (99.9999%) or higher purity, and the stability requirements for electronic gas quality are also becoming more stringent. Advanced processes below 10 nanometers have increasingly higher requirements for impurity filtration, and the cleanliness of the wafer fab production environment must be further improved to ensure that semiconductor wafers are not contaminated and production yield is improved. From 28 nanometers to 7 nanometers, the metal impurity requirements for products must be reduced by 100 times, and the volume of contaminant particles must be reduced by 4 times. As the process moves below 10 nanometers, the cleanliness requirements will only become stricter. For example, a 28-nanometer wafer may have 10 contaminant particles, but a 7-nanometer wafer can only have 1. Wafers using advanced processes have very thin film layers and are very sensitive to oxygen, easily oxidized, so the demand for specialty gases in wafer manufacturing is greater. Future 3/5 nanometers have entered the atomic scale. Therefore, whether specialty gas suppliers can provide higher purity gases is a key condition for entering the mainstream international wafer fabs.

In terms of gas precision barriers, accurately controlling the ratio precision of different gases is another barrier; for mixed gases, the ratio precision is the core parameter. Gas mixing refers to the method of mixing two or more components of gases in specific proportions according to different needs, using methods such as weight method, partial pressure method, and dynamic volume method. The cumulative error control, mixing precision, and impurity control during the mixing process are extremely demanding. As the number of product components increases and the ratio precision rises, gas suppliers are often required to perform fine operations on multiple ppm or even ppb level gas components, and the difficulty and complexity of the configuration process also increase significantly. Especially for lithography gases, the precision control of mixed gases is more important. Lithography gases include Ar/F/Ne mixed gas, Kr/Ne mixed gas, Ar/Ne mixed gas, Kr/F/Ne mixed gas, etc.

2. Qualification barriers. The qualification certification for enterprise customers is difficult and takes a long time. Customers' selection of gas suppliers requires two rounds of strict audit and certification: factory audit and product certification. The audit and certification cycle for photovoltaic energy and optical fiber and cable fields is usually 0.5-1 year, for display panels it is usually 1-2 years, and for integrated circuits, the audit and certification cycle is as long as 2-3 years. On the other hand, the cost of electronic specialty gases in the downstream manufacturing process is relatively low, but they have a significant impact on the performance of electronic products. Once quality problems occur, downstream customers will suffer significant losses. To maintain stable gas supply, customers will not easily change gas suppliers after establishing a cooperative relationship with them.

Current Development Status and Future Development Space of Domestic Electronic Gases

The global electronic gas industry is highly concentrated, with obvious oligopoly

The electronic gas industry is highly concentrated, and the global electronic specialty gas market is monopolized by leading enterprises in several developed countries, and domestic enterprises face fierce competition. Globally, the main providers of specialty electronic gases include American Gas Chemical, American Praxair, Japan's Showa Denko, UK's BOC (acquired by Linde in 2006), Germany's Linde (merged with American Praxair in 2018), France's Air Liquide, and Japan's Taiyo Nippon Sanso. The global specialty gas market is dominated by American Air Products, Praxair, Air Liquide, Taiyo Nippon Sanso, and Germany's Linde, accounting for 94% of the market share; in the domestic market, several overseas leading enterprises also control 85% of the market share, and the situation of electronic specialty gases being controlled by others urgently needs to be changed.

Overseas leading electronic specialty gas companies have company standards higher than industry standards. Internationally, the SEMI standard (International Semiconductor Equipment and Materials Association standard) is generally adopted for electronic gases, but several major gas companies abroad have their own company standards, which highlight the technical level characteristics of each company, with product purity generally 1-2 orders of magnitude higher than SEMI, and each has its own characteristics in analysis and testing, packaging, usage methods, and application technology descriptions. Some companies only indicate "to be negotiated with users" for some key impurities (metal impurities, particulate impurities, etc.), indicating that electronic gas technology and market competition are very fierce, and key technologies are kept confidential.

The domestic electronic gas market is growing rapidly, with foreign companies dominating

With the transfer of the semiconductor and flat panel display industry chain, the domestic electronic gas market is growing significantly faster than the global growth rate. The president of American Praxair once said that China will be the last battlefield for global electronic gas competition. Currently, the domestic electronic gas market is mainly monopolized by six companies: American Gas Chemical, American Praxair, Japan's Showa Denko, UK's BOC (now a subsidiary of Linde Group), France's Air Liquide, and Japan's Taiyo Nippon Sanso, accounting for 85% of the market share. Domestic enterprises are mainly concentrated in the mid-to-low-end market.

Domestic electronic gases have begun to occupy a certain market share. After years of development, some domestic enterprises have overcome technical difficulties in some products, such as Sichuan Kemeite's CF4 entering TSMC's 12-inch Tainan 28nm wafer processing production line, and Jinhong Gas developing 7N electronic-grade ultra-pure ammonia, breaking the monopoly of foreign gas companies on ultra-pure ammonia. Other listed companies include Yoke Technology, Juhua Group, NDGD, etc.

After more than 30 years of development, China's semiconductor electronic specialty gases have achieved good results. The 718th Research Institute of China Shipbuilding Industry Corporation, Luling Electronics, Guangdong Huate, etc., have made breakthroughs in 12-inch wafer products and achieved stable mass supply; Sichuan Kemeite's CF4 has entered TSMC's 12-inch Tainan 28nm wafer processing production line. In May 2018, the 718th Research Institute of China Shipbuilding Industry Corporation held a groundbreaking ceremony for the second phase of the project. After full production in 2020, it will produce 20,000 tons of high-purity electronic gases annually, and the production capacity of four products, nitrogen trifluoride, tungsten hexafluoride, hexafluorobutadiene, and trifluoromethanesulfonic acid, will rank first in the world. In terms of high-purity silane, Zhongning Silicon uses self-produced high-purity silane as raw material, researching and developing semiconductor-grade silane gas preparation technology with independent intellectual property rights,