What is Indium Phosphide and does it have a future?
Latest update time：2022-03-18 11:22
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Indium phosphide is a compound of phosphorus and indium. As a semiconductor material, indium phosphide has excellent properties. Semiconductor devices made with indium phosphide substrates have the characteristics of high saturated electron drift velocity, suitable luminous wavelength for low-loss optical fiber communication, strong radiation resistance, good thermal conductivity, high photoelectric conversion efficiency, and high bandgap width. Therefore, indium phosphide substrates can be widely used in the manufacture of optical module devices, sensor devices, high-end RF devices, etc. In order to let everyone know more about indium phosphide, the article introduces indium phosphide in three parts. First, the article introduces the basic properties, preparation methods and research difficulties of indium phosphide; secondly, the article introduces the current market structure of indium phosphide, major manufacturers and market share, etc.; finally, the article ends with an introduction to the overall industrial chain of indium phosphide, introducing the material production end, device manufacturing end and terminal application end of indium phosphide, etc. I hope everyone knows some problems about indium phosphide.
Material properties
1. Basic Introduction
Indium phosphide (InP) is an important compound semiconductor material with many advantages such as high saturated electron drift velocity, strong radiation resistance, good thermal conductivity, high photoelectric conversion efficiency, and wide bandgap. Indium phosphide has a zinc blende crystal structure, a bandgap of 1.34eV, and a mobility of 3000-4500 cm2/(VS) at room temperature.
It
is widely used in optical communications, high-frequency millimeter-wave devices, optoelectronic integrated circuits, and solar cells for outer space. With the above material properties, semiconductor devices made of indium phosphide substrates are widely used in the production of RF devices, optical modules, LEDs (Mini LED and Micro LED), lasers, detectors, sensors, space solar cells, and other devices due to their special material properties. They have broad application space in 5G communications, data centers, new generation displays, artificial intelligence, unmanned driving, wearable devices, aerospace, and other fields.
Indium phosphide semiconductor materials have a wide bandgap structure, and electrons move quickly through InP materials. Therefore, satellite signal receivers and amplifiers made with InP chips can operate at extremely high frequencies above 100 GHz, have a wide bandwidth, are less affected by the outside world, and have high stability. Therefore, InP is a more advanced semiconductor material than GaAs, and it is possible to promote the satellite communication industry to develop to higher frequency bands.
Compared with gallium arsenide (GaAs), indium phosphide (InP) has outstanding advantages in electrical and other physical properties, and has an advantage in the field of semiconductor optical communications. As a comparable material to gallium arsenide, indium phosphide has the following advantages: (1) InP has the advantages of high electron peak drift velocity, high bandgap width, and high thermal conductivity. The direct transition band gap of InP is 1.34eV, corresponding to the band with the smallest transmission loss in optical communication; the thermal conductivity is higher than that of GaAs, and the heat dissipation performance is better; (2) InP has more advantages than GaAs in device manufacturing. The high current peak-to-valley ratio of InP devices determines the high conversion efficiency of the device; the inertial energy time constant of InP is half that of GaAs, and the working efficiency limit is twice that of GaAs devices; InP devices have better noise characteristics; (3) InP as a substrate material has the following main application paths. Optoelectronic devices, including light sources (LEDs) and detectors (APD avalanche photodetectors), are mainly used in optical fiber communication systems; integrated lasers, light detectors and amplifiers are optoelectronic integrated circuits, which are essential components of the new generation of 40Gb/s communication systems. The article introduces its wide range of application scenarios. It is worth noting that due to the limited information and knowledge of the author, although many application scenarios are introduced, it is undeniable that the author's understanding of this new material and the application of the scenario are completely incomplete. In many fields, the author's introduction is incomplete and insufficient. Please be aware of this!
Figure 1. Main application areas of indium phosphide
(II) Several methods for preparing indium phosphide
(1) Synthesis technology of indium phosphide polycrystal
The melting point of indium is 1070℃. At this temperature, indium phosphide material has a very high dissociation pressure, and the dissociation pressure at the melting point is 2.75MPa. According to the functional relationship between Antoine's saturated vapor pressure and temperature, lgP = AB/(T+C), under this condition, the vapor pressure of phosphorus has exceeded 10MPa, which is much greater than the dissociation pressure of indium phosphide. Therefore, it is very difficult to synthesize indium phosphide single crystals directly from phosphorus and indium in a single crystal furnace. Therefore, high-purity indium and high-purity phosphorus are generally synthesized through polycrystalline synthesis to synthesize indium phosphide polycrystalline material, and then indium phosphide polycrystalline material is used to grow indium phosphide single crystals.
The main method for preparing indium phosphide single crystals is to use a high-pressure single crystal furnace, and the dislocation density of the crystal is reduced by doping with isoelectronic impurities. For vapor phase epitaxy, the disproportionation method of the In-PCl3-H2 system is mostly used. In this process, the indium phosphide layer is grown by the reaction between indium (99.9999%) and phosphorus trichloride (99.999%).
(2) Solute diffusion method
The solute diffusion method (SSD) is the earliest method used for the synthesis of indium phosphide polycrystals. It is a method in which phosphorus vapor diffuses in the indium melt at 900℃ to 1000℃ and then reacts to form indium phosphide polycrystals. Due to its low growth temperature, it can reduce the contamination of indium phosphide polycrystals by Si impurities in the crystal, improve the purity of the crystal, and effectively increase the carrier concentration of the crystal. The carrier concentration can reach 1014cm
-3
. However, compared with other methods, the amount of polycrystals synthesized at one time is small and the synthesis speed is slow, resulting in high production costs and unable to meet the needs of industrial mass production. It has basically been eliminated.
(3) In situ direct synthesis method
In-situ direct synthesis methods include: phosphorus vapor injection method; liquid phosphorus liquid sealing method; high-pressure direct synthesis method. One method of in-situ direct synthesis is to place indium and phosphorus in the same crucible, and then cover the top of the crucible with a heating hood. When this area is heated to a certain temperature, the phosphorus in the crucible first turns into phosphorus vapor, and then the phosphorus vapor is heated and decomposed to this wall, and the temperature decreases to form liquid phosphorus. When a certain amount is reached, the liquid phosphorus drips into the indium melt and reacts with the indium melt instantly until all the indium melt and liquid phosphorus are synthesized and converted into indium phosphide melt. However, during the solid-liquid conversion process after the solid red phosphorus in the crucible is heated, a large amount of phosphorus will volatilize, making it difficult to use the quartz observation window to observe the crystal growth. With the advancement of detection technology, X-ray scanning technology is now used to observe the contact and growth of the seed crystal. Although the monitoring of crystal growth is solved, this method will cause a lot of phosphorus waste and convert red phosphorus into white phosphorus. White phosphorus is highly toxic, has a low ignition point and is easy to spontaneously combust, so the process cost is too high and the risk is also high.
(4) VNG method
The VNG method is an important method for preparing indium phosphide. Compared with other methods, the VGF method is advanced as follows: First, in terms of single crystal diameter, the maximum diameter of single crystals grown by the HB method is generally 3 inches, and the maximum diameter of single crystals grown by the LEC method can reach 12 inches. However, the investment cost of single crystal equipment grown by the LEC method is high, and the grown crystals are uneven and have a high dislocation density. At present, the single crystals grown by the VGF method and the VB method can reach a maximum diameter of 8 inches, and the grown crystals are relatively uniform and have a low dislocation density; second, in terms of single crystal quality, compared with other methods, the crystals grown by the VGF method have a low dislocation density and stable production efficiency; third, in terms of production cost, the HB method has the lowest cost, the LEC method has the highest cost, and the products produced by the VB method and the VGF method have similar performance, but the VGF method eliminates the mechanical transmission structure and can stably produce single crystals at a lower cost.
Figure 2.
Single
crystal preparation diagram
Note: CITIC Securities Research Institute
After the above preparation, the industrial preparation process of indium phosphide also includes the common parts of the compound semiconductor production process, such as crystal pulling, rounding, cutting, grinding, etching, polishing, cleaning and other processes; the semiconductor epitaxial wafer production process is mainly epitaxial growth on the basis of polished wafers, etc. From indium phosphide materials to indium phosphide devices and terminal applications, it also includes a process of substrate-device-terminal application. Its main types and reference standards can be seen in the figure below:
Figure 3.
Main
types of indium phosphide and reference standards
Note: Sourced from Yole
(5) Research Difficulties
At present, the research focuses on the following aspects: First, develop the direct synthesis technology of InP polycrystals, simplify the synthesis process and reduce costs; second, develop the preparation technology of large-diameter InP single crystals, reduce twins, improve the crystallization rate and reduce costs; third, reduce the dislocation density of large-diameter InP single crystals. In addition to using vertical gradient solidification technology (VGF) and vapor pressure controlled CZ (VCz) and other processes, improving the thermal field structure, reducing thermal stress, controlling doping conditions and other process measures can also achieve this goal; fourth, improve the preparation technology of 4-inch InP wafers. In particular, improve the surface quality of the material; fifth, improve the thermal stability of semi-insulating InP single crystals and reduce the use of dopant Fe.
Current competitive landscape
The technical barriers to the preparation of indium phosphide single crystals are high. The technologies that can enable the mass growth of single crystals mainly include high-pressure liquid-sealed direct pulling method (LEC), vertical temperature gradient solidification method (VGF) and vertical Bridgman method (VB). AXT of the United States and Sumitomo of Japan can grow indium phosphide single crystals with a diameter of 150 mm using VGF and VB technology respectively. The 4-inch diameter Fe-doped semi-insulating single crystal substrate prepared by Sumitomo of Japan using the VB method can be mass-produced. The VGF production technology requires that the warpage of the crystal surface is less than 15 microns, and the lower the dislocation level, the better. There is still a large gap between China's indium phosphide preparation technology and the international level. The production capacity of domestic enterprises is small, and the production capacity of large-size indium phosphide wafers is insufficient.
However, benefiting from the increase in downstream market demand, the market size of indium phosphide substrate materials will continue to expand. According to Yole's forecast, the global indium phosphide substrate (equivalent to two inches) is expected to sell 1.2819 million pieces in 2026, with a compound growth rate of 14.40% from 2019 to 2026; the global indium phosphide substrate market size in 2026 is US$202 million, with a compound growth rate of 12.42% from 2019 to 2026. The figure below is the indium phosphide market forecast.
Figure 4.
Indium
Phosphide Market Development Forecast
Note: Sourced from Yole
The research work on indium phosphide single crystal materials has been carried out in China for more than 30 years, but the research scale, project support and investment in indium phosphide single crystal growth technology are relatively small, and there is still a large gap with the international level. At present, except for Tongmei’s Beijing factory, there are no manufacturers in China that can mass-produce single crystal substrates. However, traditional gallium arsenide and germanium single crystal substrate manufacturers have also noticed the opportunities in this market. Manufacturers including Zhuhai Dingtai Xinyuan Company, Yunnan Germanium Industry, Pioneer Rare Materials, Zhongke Jingdian, and Dongyi Crystal are actively deploying. At present, because domestic laser epitaxy manufacturers have not yet achieved large-scale production, indium phosphide substrates account for less than 2% of the global total market share.
The upstream of the indium phosphide industry chain is the production and processing of crystal growth, substrates and epitaxial wafers. From the perspective of raw materials and equipment for substrate production, the raw materials include metal indium, red phosphorus, crucibles, etc.; production equipment involves crystal growth furnaces, grinders, polishers, cutting machines, detection and testing equipment, etc. The midstream of the industry chain includes integrated circuit design, manufacturing and packaging and testing. The downstream applications of the industry chain mainly involve optical communications, unmanned driving, artificial intelligence, wearable devices and other fields.
Upstream companies in the indium phosphide industry chain include substrate manufacturers and epitaxial manufacturers, such as Beijing Tongmei, Japan JX, Sumitomo and other domestic substrate manufacturers, as well as IQE, Taiwan Lianya Optoelectronics, Taiwan New Optoelectronics, II-VI, Taiwan Inter-Lei and other epitaxial manufacturers. The device field includes Finisar, Lumentum, AOI, Mitsubishi and other companies. Downstream host manufacturers include Huawei, ZTE, Nokia, Cisco and other companies. Terminal applications include China Mobile, China Telecom, China Unicom, Tencent, Alibaba, Apple, Google, Amazon, Meta and other companies.
From the perspective of the market structure, the concentration of leading companies in the indium phosphide substrate material market is very high, and the main suppliers include Sumitomo, Beijing Tongmei, Japan JX, etc. According to Yole data, the top three manufacturers in the world accounted for more than 90% of the indium phosphide substrate market in 2020, among which Sumitomo is the world's largest manufacturer, accounting for 42%; Beijing Tongmei ranks second, accounting for 36%.
1. ATX
AXT, Inc. is a high-tech company in Silicon Valley, USA. It was founded in 1986 and listed on NASDAQ in 1998 with the stock code AXTI. The company is mainly engaged in the manufacture of III-V compounds including gallium arsenide, indium phosphide, etc. and single crystal germanium semiconductor substrate materials. Its products are mainly used in wireless optical fiber communications, infrared optics, radiation and light detectors, aerospace solar energy and other fields. They are exported to Europe, America, Japan, South Korea, Singapore, Taiwan and other regions, ranking among the top three in the industry.
As a world-leading compound semiconductor substrate manufacturer, AXT has invested in the upstream and downstream fields of compound semiconductor production such as gallium arsenide and indium phosphide, and directly controls and participates in ten related companies. Beijing Boyu is one of its holding subsidiaries.
2. InPACT, France
Researchers from InPACT SA in France used FEMAG/CZ software to simulate and analyze the liquid-encapsulated Czochralski (LEC) process of InP crystal growth and studied ways to reduce the dislocation density of InP. In the traditional LEC single crystal growth process, they added a heat shield and changed the growth furnace structure to reduce the thermal gradient during crystal growth.
Researchers from InPACT SA in France used FEMAG/CZ software to simulate and analyze the liquid-encapsulated Czochralski (LEC) process of InP crystal growth and study ways to reduce the dislocation density of InP. In the traditional LEC single crystal growth process, they added heat shields and changed the structure of the growth furnace to reduce the thermal gradient during crystal growth. The shape of these heat shields was optimized by global numerical simulation of heat transfer and thermal stress using FEMAG/CZ. Through optimization, thermal stress was reduced by 50% and dislocation density was significantly reduced (from 50,000/cm to 30,000/cm in the upper part of a 2-inch iron-included crystal). They also found that reducing the thermal gradient in the melt (from 12K/cm to 6K/cm) will lead to destabilization of the interface (this effect will be more significant for tin-included crystals).
Industry Chain Distribution
The upstream of the indium phosphide industry chain is the production and processing of crystal growth, substrates and epitaxial wafers. From the perspective of raw materials and equipment for substrate production, the raw materials include metal indium, red phosphorus, crucibles, etc.; production equipment involves crystal growth furnaces, grinders, polishers, cutting machines, detection and testing equipment, etc. The midstream of the industry chain includes integrated circuit design, manufacturing and packaging and testing. The downstream applications of the industry chain mainly involve optical communications, unmanned driving, artificial intelligence, wearable devices and other fields. See Figure 4 below for details.
Figure 5.
Distribution
of Indium Phosphide Industry Chain
Note: The picture comes from the official website of Beijing Tongmei Crystal Technology Co., Ltd.
Next, the article will introduce the industrial chain of indium phosphide according to this classification.
(I) Upstream materials and equipment: Indium phosphide single crystals, Indium phosphide substrates, etc.
Indium phosphide single crystal materials and indium phosphide substrates are at the upstream of the industrial chain, and 80% of the market share is monopolized by foreign manufacturers. At present, Japan's Sumitomo is the industry leader, occupying 60% of the global market share, the United States's Tongmei has a market share of 15%, and British and French companies have a market share of 10% and 5% respectively. At present, the annual domestic substrate consumption totals about 30,000 pieces, accounting for less than 2% of the global total market share. There are few companies in China that can produce indium phosphide wafers. Zhuhai Dingtai Xinyuan Company has 30 patents and 10 patents are being applied for. The indium phosphide crystal growth rate can reach 40%-50%. The technical team and technical support behind the company are the Chinese Academy of Sciences. At present, Dingtai Xinyuan has mastered the production technology of 2-inch to 6-inch wafers.
Indium phosphide substrate materials are at the upstream of the optical communication industry chain, and there is an obvious foreign monopoly. At present, due to the high barriers in the growth equipment and technology of indium phosphide single crystals, there are few participants in the indium phosphide market, and they are mainly a few foreign manufacturers. The main suppliers include Japan's Sumitomo, Japan Energy, the United States AXT (made in China), France InPact, the United Kingdom WaferTech, etc. The above five manufacturers account for nearly 80% of the global market share.
(II) Midstream device production: including optical module devices, sensor devices, and RF devices
Optical modules are core components of optical communications. They are interface modules that realize information transmission between devices through photoelectric conversion. They are mainly used in communication base stations and data centers. Indium phosphide substrates are used to manufacture lasers and receivers in optical modules. 5G communication is a new generation of broadband mobile communication technology with high speed, low latency and large connection characteristics. The use of optical modules in 5G base stations is significantly higher than that in 4G base stations. With the large-scale deployment of 5G base station construction and the changes in the network structure of 5G base stations, the demand for optical modules will be greatly driven. According to Yole statistics, the global telecommunications optical module (including 5G communication market) market size will increase from US$3.7 billion in 2019 to US$5.6 billion in 2025, with a compound growth rate of 7.15% from 2019 to 2025.
Since indium phosphide has the characteristics of high saturated electron drift velocity, good thermal conductivity, high photoelectric conversion efficiency, and high bandgap width, wearable devices made with indium phosphide substrates have good pulse response and good signal-to-noise ratio. Therefore, indium phosphide substrates can be used to manufacture sensors in wearable devices to monitor vital signs such as heart rate, blood oxygen concentration, blood pressure, and even blood sugar levels. In addition, laser sensors made with indium phosphide substrates can emit invisible light that does not damage vision and can be used in products such as virtual reality (VR) glasses and automotive radars.
Indium phosphide substrates have an application market in the fields of manufacturing high-frequency and high-power devices, optical fiber communications, wireless transmission, radio astronomy and other RF devices. RF devices made using indium phosphide substrates (hereinafter referred to as "Indium phosphide-based RF devices") have shown excellent performance in application scenarios such as satellites and radars. Indium phosphide-based RF devices are highly competitive in the RF front-end of radar and communication systems, analog/mixed signal wide-bandwidth circuits, and are suitable for applications such as high-speed data processing and high-precision wide-bandwidth A/D conversion. In addition, Indium phosphide-based RF device-related devices such as low-noise amplifiers, modules and receivers are also widely used in satellite communications, millimeter-wave radars, active and passive millimeter-wave imaging and other equipment. At bandwidth levels above 100 GHz, the use of Indium phosphide-based RF devices has obvious advantages in wireless transmission in backhaul networks and point-to-point communication networks. In the future, in 6G communication and even 7G communication wireless transmission networks, Indium phosphide substrates are expected to become the mainstream substrate material for RF devices.
(III) Downstream terminal application sales: cloud vendors Amazon, Alibaba, etc.
From the perspective of global cloud computing market share, American manufacturers dominate, Amazon is the only industry leader, and Alibaba Cloud ranks fourth. According to Gartner statistics, Amazon, Microsoft, and Google accounted for 72% of the market share in 2019. Amazon ranks first in the world with a market share of 45%, followed by Microsoft with 17.9%, Google with 9.1%, and Alibaba Cloud with 5.3%.
Note: The author has processed some of the data in the article based on official data; the sources of all pictures have been noted, such as Beijing Tongmei, Yole, etc. In addition, the company rankings in the article have nothing to do with the company's strength and do not contain the author's subjective views. It is only a question of introduction. At the same time, due to the limited information of the author, if there is any inappropriate introduction, the author now apologizes! Please be informed.
*Disclaimer: This article is originally written by the author. The content of the article is the author's personal opinion. Semiconductor Industry Observer reprints it only to convey a different point of view. It does not mean that Semiconductor Industry Observer agrees or supports this point of view. If you have any objections, please contact Semiconductor Industry Observer.
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