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In the semiconductor industry chain, especially in the third-generation semiconductor (wide bandgap semiconductor) industry chain, the distinction between substrate and epitaxial layer is crucial.   What is the significance of the epitaxial layer? What is the difference between it and the substrate?   First of all, the substrate is a wafer made of semiconductor single-crystal material. It can be used as a direct input in the wafer manufacturing process to produce semiconductor devices, or it can be processed by the epitaxial process to produce epitaxial wafers. The substrate is the foundation of the wafer, located at the bottom layer, and supports the entire wafer. In the chip manufacturing process, the wafer is cut into multiple independent dies, and after packaging, it becomes the chip we are familiar with. The substrate is the base at the bottom of the chip, and the complex structure of the chip is built on this base. Secondly, epitaxy refers to the growth of a new single-crystal layer on a finely processed single-crystal substrate. This new single crystal can be the same as the substrate material or a different material, which is called homoepitaxial or heteroepitaxial respectively. Since the new single-crystal layer grows according to the crystal phase of the substrate, it is called an epitaxial layer. Its thickness is usually several microns. Taking silicon as an example, the significance of silicon epitaxial growth is to grow a single crystal layer with a good crystal structure with the same crystal orientation, different resistivity, and thickness on a silicon single-crystal substrate with a specific crystal orientation. The substrate after epitaxial growth is called an epitaxial wafer, and its structure can be expressed as an epitaxial layer plus a substrate. The manufacturing process of the device is carried out on the epitaxial layer. Epitaxy is divided into homoepitaxial and heteroepitaxial. Homoepitaxial refers to growing an epitaxial layer of the same material as the substrate on a substrate. The significance of homoepitaxial is to improve the stability and reliability of the product. Although the homoepitaxial layer is made of the same material as the substrate, the material purity and uniformity of the wafer surface can be improved through epitaxial treatment. Compared with the polished wafer with mechanical polishing, the substrate surface treated with epitaxial treatment has higher flatness, higher cleanliness, fewer micro defects, and fewer surface impurities, so the resistivity is more uniform, and it is easier to control defects such as surface particles, stacking faults, and dislocations.   Epitaxy not only improves the performance of the product but also ensures the stability and reliability of the product. In the CMOS silicon process, epitaxial growth on the wafer substrate is a crucial process step. 1. Improve crystal quality: The defects and impurities of the initial substrate can be improved by the growth of the epitaxial layer. The wafer substrate may produce certain defects and impurities during the manufacturing process. The growth of the epitaxial layer can generate a high-quality, low-defect, and impurity-concentration single-crystal silicon layer on the substrate, which is crucial for subsequent device manufacturing. 2. Uniform crystal structure: Epitaxial growth can ensure the uniformity of the crystal structure and reduce the influence of grain boundaries and defects in the substrate material, thereby improving the crystal quality of the entire wafer. 3. Improve electrical performance and optimize device characteristics: By growing an epitaxial layer on the substrate, the doping concentration and type of silicon can be precisely controlled to optimize the electrical performance of the device. For example, the doping of the epitaxial layer can accurately adjust the threshold voltage and other electrical parameters of the MOSFET. 4. Reduce leakage current: High-quality epitaxial layers have lower defect density, which helps to reduce leakage current in the device, thereby improving the performance and reliability of the device. 5. Support advanced process nodes and reduce feature size: In smaller process nodes (such as 7nm, and 5nm), the device feature size continues to shrink, requiring more refined and high-quality materials. Epitaxial growth technology can meet these requirements and support high-performance and high-density integrated circuit manufacturing. 6. Improve the breakdown voltage: The epitaxial layer can be designed to have a higher breakdown voltage, which is critical for manufacturing high-power and high-voltage devices. For example, in power devices, the epitaxial layer can increase the breakdown voltage of the device and increase the safe operating range. 7. Process compatibility and multi-layer structure: Epitaxial growth technology allows the growth of multi-layer structures on the substrate, and different layers can have different doping concentrations and types. This is very helpful for manufacturing complex CMOS devices and achieving three-dimensional integration. 8. Compatibility: The epitaxial growth process is highly compatible with existing CMOS manufacturing processes and can be easily integrated into existing manufacturing processes without significantly modifying the process lines.

Sapphire thermocouple protection tubes and sapphire thermocouple sheaths can withstand high temperatures up to 2000 degrees Celsius and pressures up to 3000 bar, making them highly suitable for harsh environments such as chemical processing, petrochemical refining, and the glass industry. Compared to alumina thermocouple protection tubes and ceramic thermocouple protection tubes, sapphire thermocouple protection tubes and sheaths offer better material stability. They are suitable for use in high-temperature fields such as heavy oil combustion reactors and metallurgy, making them ideal replacements for alumina thermocouple protection tubes. For more details, visit: https://www.galliumnitridewafer.com/ Sapphire thermocouple protection tubes have replaced ceramic tubes that cannot withstand metal diffusion, such as in the production of lead glass, where Pt thermocouple sheaths would melt into the glass, necessitating reproduction. Currently, sapphire thermocouple protection tubes and sheaths have been successfully used in the following areas: Semiconductor manufacturing: Alumina sapphire sheaths with up to 99.995% purity ensure a contamination-free production process. Corrosive environment manufacturing: Concentrated or boiling mineral acids, high-temperature reactive oxides. Glass and ceramic industry: Replacing Pt probes to ensure contamination-free processes. Instrument manufacturing: Microwave digesters, high-temperature reaction furnaces, laboratory testing instruments, etc. Optical applications: UV lamps, automotive lights. Heavy oil reactors: Used in petrochemical and other areas. Energy sector: For the removal of NOx and other pollutants. Sapphire thermocouples, consisting of an externally sealed alumina protective sheath and an internal thermocouple capillary, also referred to as sapphire thermocouples. Due to the optical transparency and non-porosity of the single-crystal material of the sapphire sheaths, these thermocouples exhibit excellent high-temperature resistance and the ability to shield environmental temperature effects on the thermocouple. Sapphire sheaths can withstand temperatures up to 2000 degrees Celsius and pressures of 3000 bar, making them extremely suitable for harsh environments such as chemical processing, chemical, oil refining, and glass industries. Sapphire sheaths offer superior material stability compared to alumina ceramic tubes and are used in many high-temperature fields such as heavy oil combustion reactors and metallurgy. Sapphire sheaths have already replaced ceramic tubes that cannot resist metal diffusion, such as in lead glass production, where Pt thermocouple sheaths would melt into the glass, leading to the need for reproduction.      

SiC is a binary compound formed by Si element and C element in 1:1 ratio, that is, 50% silicon (Si) and 50% carbon (C), and its basic structural unit is SI-C tetrahedron.   For example, Si atoms are large in diameter, equivalent to an apple, and C atoms are small in diameter, equivalent to an orange, and an equal number of oranges and apples are piled together to form a SiC crystal. SiC is A binary compound, in which the Si-Si bond atom spacing is 3.89 A, how to understand this spacing? At present, the most excellent lithography machine on the market has a lithography accuracy of 3nm, which is a distance of 30A, and the lithography accuracy is 8 times that of the atomic distance. The Si-Si bond energy is 310 kJ/mol, so you can understand that the bond energy is the force that pulls these two atoms apart, and the greater the bond energy, the greater the force that you need to pull apart. The Si-C bond atomic spacing is 1.89 A and the bond energy size is 447 kJ/mol. Compared with traditional silicon-based semiconductor materials, it can be seen from the bond energy that the chemical properties of silicon-based semiconductor materials are more stable. It can be seen that any C atom is connected to the four nearest Si atoms, and conversely, any Si atom is connected to the four nearest C atoms. The SiC crystal structure can also be described by the layered structure method. As shown in the figure, several C atoms in the crystal occupy six grid sites on the same plane, forming a close-packed layer of C atoms, while Si atoms also occupy six grid sites on the same plane and form a close-packed layer of Si atoms. Each C in a close-packed layer of C atoms is connected to its nearest Si, and vice versa. Every two adjacent layers of C and Si atoms form a carbon-silicon diatomic layer. The arrangement and combination of SiC crystals are very rich, and more than 200 SiC crystal types have been discovered. This is similar to Tetris, although the smallest unit blocks are the same, but when the blocks are put together, they form different shapes. The spatial structure of SiC is slightly more complex than Tetris, and its smallest unit changes from a small square to a small tetrahedron, a tetrahedron composed of C and Si atoms. In order to distinguish the different crystal forms of SiC, the Ramsdell method is mainly used for labeling at present. The method uses the combination of letters and numbers to represent the different crystal forms of SiC. Letters are placed at the back to indicate the cell type of the crystal. C stands for Cubic (first letter of the English cubic), H stands for Hexagonal (first letter of the English), R stands for Rhombus (first letter of the English rhombus). Numbers are placed first to represent the number of layers of the Si-C diatomic layer of the basic repeating unit. In addition to 2H-SiC and 3C-SiC, other crystalline forms can be regarded as a mixture of sphalerite and wurtzite structure, that is, close-packed hexagonal structure. The C-plane refers to the (000-1) crystal face of the silicon carbide wafer, that is, the surface on which the crystal is cut along the negative direction of the C-axis, and the terminating atom of the surface is the carbon atom. The silicon surface refers to the (0001) crystal face of the silicon carbide wafer, that is, the surface on which the crystal is cut along the positive direction of the C-axis, and the terminating atom of the surface is the silicon atom. The difference between C-plane and silicon plane will affect the physical and electrical properties of silicon carbide wafer, such as thermal conductivity, electrical conductivity, carrier mobility, interfacial state density and so on. The choice of C-plane and silicon plane will also affect the manufacturing process and performance of silicon carbide devices, such as epitaxial growth, ion implantation, oxidation, metal deposition, contact resistance, etc.                                

Wafer surface profile parameters Bow, Warp, TTV are very important factors that must be considered in chip manufacturing. Together, these three parameters reflect the flatness and thickness uniformity of the silicon wafer and have a direct impact on many key steps in the chip manufacturing process. TTV is the difference between the maximum and minimum thickness of a silicon wafer. This parameter is an important index used to measure the thickness uniformity of silicon wafers. In a semiconductor process, the thickness of the silicon wafer must be very uniform over the entire surface. Measurements are usually made at five locations on the silicon wafer and the maximum difference is calculated. Ultimately, this value is the basis for judging the quality of the silicon wafer. In practical applications, the TTV of a 4-inch silicon wafer is generally less than 2um, and that of a 6-inch silicon wafer is generally less than 3um. Bow Bow in semiconductor manufacturing refers to the bending of silicon wafers. The word probably comes from a description of the shape of an object when it is bent, like the curved shape of a bow. The Bow value is defined by measuring the maximum deviation between the center and edge of the silicon wafer. This value is usually expressed in micrometers (µm). The SEMI standard for 4-inch silicon wafers is Bow< 40um. Warp Warp is a global feature of silicon wafers, indicating the maximum distance of the wafer surface from the plane. It measures the distance between the highest and lowest points of a silicon wafer. The SEMI standard for 4-inch silicon wafers is Warp< 40um. What's the difference between TTV,Bow,Warp? TTV focuses on changes in thickness and is not concerned with the bending or distortion of the wafer. Bow focuses on the overall bend, mainly considering the bend of the center point and the edge. Warp is more comprehensive, including bending and twisting of the entire wafer surface. Although these three parameters are related to the shape and geometric properties of the silicon wafer, they are measured and described differently, and their impact on the semiconductor process and wafer processing is also different. Effect of TTV, Bow, Warp on semiconductor process： First of all, the smaller the three parameters, the better. The larger the TTV, Bow, and Warp, the greater the negative impact on the semiconductor process, so if the values of the three exceed the standard, the silicon chip will be scrapped. Influence on the lithography process: Focal depth problem: During lithography, changes in focal depth may result, which affects the sharpness of the pattern. Alignment problems: May cause the wafer to shift during alignment, further affecting the alignment accuracy between layers. Impact on chemical mechanical polishing: Uneven polishing: May result in uneven polishing during CMP, resulting in surface roughness and residual stress. Effect on film deposition:   Uneven deposition: Convex and concave wafers may cause uneven thickness of deposited film during deposition. Impact on wafer loading:   Loading problems: Convex and concave wafers can cause damage to wafers during automatic loading.   Finally, as semiconductor practitioners, we must realize the importance of wafer profile parameters for the entire process process, and pay attention to details when doing semiconductor processes.                                                        

Epitaxial sheet (EPI) and its application Epitaxial sheet (EPI) refers to the semiconductor film grown on the substrate, which is mainly composed of P-type, quantum well and N-type. Now the mainstream epitaxial material is gallium nitride (GaN), and the substrate material is mainly sapphire. Silicon, carbonization in three, quantum Wells generally for 5 commonly used production process for metal-organic gas phase epitaxy (MOCVD), which is the core part of the LED industry, the need for higher technology and larger capital investment. At present, it can be done on the silicon substrate ordinary epitaxial layer, multi-layer structure epitaxial layer, ultra-high resistance epitaxial layer, ultra-thick epitaxial layer, the epitaxial layer resistivity can reach more than 1000 ohms, and the conductive type is: P/P++, N/N+, N/N+, N/P/P, P/N/N /N+ and many other types. Silicon epitaxial wafers are the core material used to manufacture a wide range of semiconductor devices, with applications in consumer, industrial, military and space electronics. Some of the most important microelectronics applications employ multiple production-proven and industry-standard silicon epitaxy process technologies: Diode • Schottky diode • Ultra-fast diodes • Zener diode • PIN diode • Transient Voltage Suppressor (TVS) • and others Transistor • Power IGBT • Power DMO • MOSFET • Medium power • Small signal • and others Integrated circuit/Bipolar integrated circuit • EEPROM • Amplifier • Microprocessor • Microcontroller • Radio frequency identification • and others The epitaxial selectivity is generally achieved by adjusting the relative rate of epitaxial deposition and in situ etching. The gas used is generally the chlorine-containing (Cl) silicon source gas DCS, and the selectivity of epitaxial growth is realized by the adsorption of Cl atoms on the silicon surface in the reaction is smaller than that of oxides or nitrides. Since SiH4 does not contain Cl atoms and has low activation energy, it is generally only used in low temperature total epitaxy process. Another commonly used silicon source, TCS, has low vapor pressure and is liquid at room temperature, which needs to be imported into the reaction chamber through H2 bubblers, but the price is relatively cheap, and its rapid growth rate (up to 5 um/min) is often used to grow relatively thick silicon epitaxial layers, which has been widely used in the production of silicon epitaxial sheets. Among Group IV elements, the lattice constant of Ge (5.646A) differs least from that of Si (5.431A), which makes the SiGe and Si processes easy to integrate. The SiGe single crystal layer formed by Ge in single crystal Si can reduce the band gap width and increase the characteristic cut-off frequency (fT), which makes it widely used in wireless and optical communication high frequency devices. In addition, in advanced CMOS integrated circuit processes, lattice stress introduced by the lattice constant mismatch (4%) of Ge and Si will be used to improve the mobility of electrons or holes, so as to increase the operating saturation current and response speed of the device, which is becoming a hot spot in semiconductor integrated circuit technology research in various countries.   Due to the poor electrical conductivity of intrinsic silicon, its resistivity is generally more than 200ohm-cm, and it is usually necessary to incorporate impurity gas (dopant) in the epitaxial growth to meet certain electrical properties of the device. Impurity gases can be divided into two types: N type impurity gases commonly used include phosphoane (PH3) and arsenane (AsH3), while P type is mainly borane (B2H6).  

In this issue, we delve into the application, preparation process, market size and development trend of silicon carbide epitaxy. Epitaxy refers to the growth of a layer of higher quality single crystal material on the surface of silicon carbide substrate, and the growth of a layer of silicon carbide epitaxy on the surface of conductive silicon carbide substrate, called homogeneous epitaxy; The growth of gallium nitride epitaxy layer on semi-insulated SIC substrate is called heteroepitaxy. The size of the epitaxial is also the same as the substrate, mainly 2 inches (50mm), 3 inches (75mm), 4 inches (100mm), 6 inches (150mm), 8 inches (200mm) and other specifications.   SiC carbide epitaxy can manufacture all kinds of power devices, which can be used in new energy vehicles, photovoltaic energy storage, aerospace and other fields; Gallium nitride epitaxy can manufacture various RF devices for 5G communication, radar and other fields. With the growth of demand for silicon carbide power devices in new energy vehicles, photovoltaic energy storage and other industries, the silicon carbide epitaxial market is also expanding rapidly. Industry Research data show that the global silicon carbide epitaxial market size is 172 billion US dollars in 2020, and it is expected to reach 1.233 billion US dollars by 2027. The compound annual growth rate of 32.5%, the market research company Y0LE and TECHCET released silicon carbide wafer materials report shows that the global equivalent 6-inch silicon carbide epitaxial wafer market size is expected to reach about 800,000 (YOLE) and 1,072 million (TECHCET) in 2023.   From a value point of view, the added value of the silicon carbide industry chain is concentrated upstream, and the epitaxial (including substrate) has a higher value in the silicon carbide industry chain.    According to CASA data, substrate and epitaxy, as the upstream link of the silicon carbide industry chain, account for 47% and 23% of the cost structure of silicon carbide power devices, respectively. High production barriers to high-quality silicon carbide epitaxial sheets, coupled with strong downstream demand for global silicon carbide devices, resulting in a tight supply of high-quality silicon carbide epitaxial sheets, making the value of silicon carbide epitaxial sheets in the industrial chain is relatively high. From the point of view of importance, silicon carbide crystal in the growth process will inevitably produce defects, the introduction of impurities, resulting in the quality and performance of the substrate material are not good enough, and the growth of the epitaxial layer can eliminate some defects in the substrate, so that the lattice is arranged neatly. Now almost all devices are realized on the epitaxy, so the epitaxy quality has a decisive impact on the performance of the device, and the epitaxy quality is affected by the crystal and substrate processing, epitaxy is in the middle of an industry, plays a key role.   On the one hand, the quality of silicon carbide epitaxial sheet is affected by the thickness and doping concentration of the key parameters. The epitaxial parameter requirements depend on the design of the device, and the epitaxial parameters are different according to the voltage level of the device. The greater the external thickness (the greater the difficulty), the higher the voltage can withstand, generally 100V voltage needs 1μm thickness epitaxy, 600V needs 6μm, 1200-1700V needs 10-15μm, 15000V needs hundreds of microns (about 150μm).   On the other hand, the control of SIC epitaxial defects is the key to the fabrication of high-performance devices, and defects will seriously affect the performance and reliability of SIC power devices. The epitaxial defects mainly include: substrate defects, such as microtubule, penetrating screw dislocation TSD, penetrating edge dislocation TED, base plane dislocation BPD, etc. Dislocation caused by epitaxial growth; Macro defects, such as triangle defects, carrot defects/comet defects, shallow pits, growing stacking faults, falling objects, etc. TSD and TED basically do not affect the performance of the final silicon carbide device, while BPD will lead to the degradation of device performance. Once macroscopic defects appear on the device, the device will fail to test, resulting in lower yield.   At present, the preparation methods of SiC epitaxy mainly include: chemical vapor deposition (CVD), molecular epitaxy (MBE), liquid phase epitaxy (LPE), pulsed laser deposition and sublimation (PLD).   Compared with the three preparation methods, although the epitaxy quality of silicon carbide prepared by MBE method and LPE method is better, the growth rate is too slow to meet the needs of industrialization, and CVD growth rate is higher, epitaxy quality is also in line with the requirements, and the CVD system is relatively simple and easy to operate, and the cost is lower. Chemical vapor deposition (CVD) is the most popular 4H-SiC epitaxy method at present. Its advantage is that the gas source flow, reaction chamber temperature and pressure can be effectively controlled during the growth process, which greatly reduces the epitaxial CVD process.   Summary: With the improvement of the voltage level of the device, the epitaxial thickness has developed from a few microns in the past to tens or even hundreds of microns. Domestic enterprises have gradually increased the amount of 6-inch silicon carbide epitaxy growth, and began to extend to the research and development and production of 8-inch epitaxy, but there is no large-scale supply capacity. In the field of low and medium pressure, domestic silicon carbide epitaxy can basically meet the demand, and it is very scarce in the field of high pressure. Compared with the 6-inch, 8-inch silicon carbide epitaxial edge loss is smaller, the available area is larger, and can increase production capacity, and the cost is expected to be reduced by more than 60% in the future through the improvement of production and economies of scale.

SiC helps to extend the range of electric vehicles           With the growing global demand for environmentally friendly and sustainable transportation, electric vehicles are becoming increasingly popular as a solution to reduce emissions and reduce dependence on oil. However, the range of electric vehicles has been a key issue. To solve this problem, a new generation of semiconductor materials - silicon carbide (SiC) is playing a key role in helping to expand the range of electric vehicles.             Silicon carbide is an advanced semiconductor material with many excellent properties that make it ideal for the electric vehicle industry. Here are a few key ways in which silicon carbide can help extend the range of electric vehicles.The reasons for the application of silicon carbide in the field of new energy vehicles include its high temperature stability, efficient energy conversion, high power density, fast switching characteristics, high voltage capability, and gradually mature manufacturing technology. These characteristics make silicon carbide one of the key technologies to improve the performance and driving range of new energy vehicles.           Silicon carbide devices have a higher power density and higher switching frequency than traditional silicon devices. This means that the use of silicon carbide devices in the electric drive system of electric vehicles can achieve a smaller and lighter design, reduce the space occupancy and weight of the system, and further improve the range of electric vehicles.SiC-based power electronics offer lower power losses compared to traditional silicon-based electronics. This increased efficiency reduces energy wastage during power conversion and allows more energy to be delivered to the wheels. As a result, the overall energy consumption of the EV is reduced, effectively extending its range.             With the continuous development and maturity of silicon carbide technology, more and more electric vehicle manufacturers have begun to use silicon carbide devices to improve the performance and driving range of electric vehicles. The wide application of silicon carbide will accelerate the popularity of electric vehicles and make greater contributions to environmentally friendly transportation.SiC devices can handle higher power densities due to their superior thermal properties and higher switching frequencies. This enables the design of more compact and lightweight power electronics systems. By reducing the weight of the components, less energy is required to move the vehicle, leading to improved range.          The electric vehicle industry is in a stage of rapid development, and silicon carbide, as an important technological innovation, will continue to play a key role in providing greater breakthroughs in the range of electric vehicles. In the next few years, we expect to see more electric vehicles using silicon carbide technology, further promoting the development of sustainable transportation.Overall, SiC technology contributes to the extended range of electric vehicles by improving power electronics efficiency, increasing power density, enabling faster charging, enhancing thermal management, and optimizing energy recovery during regenerative braking. These advancements help maximize the utilization of energy and improve the overall efficiency and range of electric vehicles.                       

              SiC silicon carbide is a compound semiconductor material composed of carbon and silicon elements, which is one of the ideal materials for making high-temperature, high-frequency, high-power, and high-voltage devices.         Compared to traditional silicon materials (Si), the bandgap width of silicon carbide (SiC) is three times that of silicon; The thermal conductivity is 4-5 times that of silicon; The breakdown voltage is 8-10 times that of silicon; The electron saturation drift rate is 2-3 times that of silicon.     The core advantages of silicon carbide raw materials are reflected in: 1) High voltage resistance characteristics: lower impedance, wider bandgap, able to withstand larger currents and voltages, resulting in smaller product designs and higher efficiency; 2) High frequency resistance characteristics: SiC devices do not have current trailing during the shutdown process, which can effectively improve the switching speed of the component (approximately 3-10 times that of Si), suitable for higher frequencies and faster switching speeds; 3) High temperature resistance: SiC has higher thermal conductivity compared to silicon and can operate at higher temperatures.        From the perspective of process flow; SiC powder undergoes crystallization, processing, cutting, grinding, polishing, and cleaning processes to ultimately form a substrate. The substrate undergoes epitaxial growth to obtain an epitaxial wafer. Epitaxial wafers are manufactured into devices through steps such as photolithography, etching, ion implantation, and deposition.     Cut the wafer into dies, package the devices, and assemble them into modules in a special casing. The industrial chain includes upstream substrate and epitaxial, midstream device and module manufacturing, and downstream terminal applications.        Power devices made of silicon carbide are divided into two categories based on their electrical performance differences, and are widely used in fields such as new energy vehicles, photovoltaic power generation, rail transit, and 5G communication. According to the different electrical properties, devices made of silicon carbide materials are divided into conductive silicon carbide power devices and semi insulating silicon carbide devices, with different terminal application fields for the two types of silicon carbide devices.      Conductive silicon carbide power devices are mainly made by growing silicon carbide epitaxial layers on conductive substrates, obtaining silicon carbide epitaxial wafers and further processing them. The varieties include Schottky diodes, MOSFETs, IGBTs, etc. They are mainly used in infrastructure construction such as electric vehicles, photovoltaic power generation, rail transit, data centers, and charging.   Semi insulating silicon carbide based RF devices are made by growing gallium nitride epitaxial layers on semi insulating silicon carbide substrates to obtain silicon carbide based gallium nitride epitaxial wafers. These devices include HEMT and other gallium nitride RF devices, mainly used for 5G communication, vehicle communication, national defense applications, data transmission, and aerospace.

    Key Semiconductor Raw Materials under Export Controls On August 1, 2023, the Ministry of Commerce and the General Administration of Customs of China officially implemented export controls on semiconductor raw materials gallium and germanium. There are various opinions in the industry regarding this move, and many people believe that it is in response to the Dutch ASML's upgraded control on the export of lithography machines. But in August 2022. The United States has included high-purity semiconductor material gallium oxide in its prohibited export control list to China. The Bureau of Industry and Security (BIS) of the US Department of Commerce has also announced the inclusion of fourth generation semiconductor materials such as gallium oxide and diamond, which can withstand high temperatures and voltages, as well as ECAD software specifically designed for chips at 3nm and below, into new export controls.     At that time, there were not many people paying attention to this export control, and it was not until a year later that China included gallium in the export control list that the industry began to pay attention to the important material of fourth generation semiconductors - gallium oxide. Gallium and germanium are key raw materials in the semiconductor industry, and their applications cover the manufacturing of first to fourth generation semiconductors. Today, with Moore's Law facing a bottleneck, semiconductor materials with larger bandgap widths, such as diamond, gallium oxide, AlN, and BN, have the potential to become the driving force for the next generation of information technology due to their excellent physical properties.     For China, it is a critical period for the development of semiconductors, and various sanctions from the United States have made the research of key revolutionary materials such as gallium oxide a key breakthrough constraint. Despite the numerous challenges, if we can succeed in this semiconductor technology revolution, China will have the potential to leap from a manufacturing powerhouse to a manufacturing powerhouse, achieving a truly unprecedented transformation in a century. This is not only a major test of China's technological strength, but also an important opportunity to showcase China's ability to face global technological challenges.   Advantages beyond silicon carbide and gallium oxide Gallium oxide, a fourth generation semiconductor material, has advantages such as large bandgap width (4.8 eV), high critical breakdown field strength (8MV/cm), and good conduction characteristics. Gallium oxide has five confirmed crystal forms, among which the most stable is β- Ga2O3. Its bandgap width is 4.8-4.9 eV, and the breakdown field strength is as high as 8 MV/cm. Its conduction resistance is much lower than that of SiC and GaN, greatly reducing the conduction loss of the device. Its characteristic parameter, Baliga Premium (BFOM), is as high as 3400, approximately 10 times that of SiC and 4 times that of GaN. Compared to silicon carbide and gallium nitride, the growth process of gallium oxide can be achieved using the liquid melt method at atmospheric pressure, which results in high quality, high yield, and low cost. Due to their own characteristics, silicon carbide and gallium nitride can only be produced by gas-phase method, which requires maintaining a high-temperature production environment and consuming a large amount of energy. This means that gallium oxide will have a cost advantage in production and manufacturing, and is suitable for domestic manufacturers to quickly increase production capacity. In comparison with silicon carbide, gallium oxide surpasses silicon carbide in almost all performance parameters. Especially with its large bandgap width and high breakdown field strength, it has significant advantages in high-power and high-frequency applications Specific Applications and Market Potential of Gallium Oxide The development prospects of gallium oxide are increasingly prominent, and the market is currently mainly monopolized by two giants in Japan, Novell Crystal Technology (NCT) and Flosfia. NCT has been investing in the research and development of gallium oxide since 2012, successfully breaking through multiple key technologies, including 2-inch gallium oxide crystal and epitaxial technology, as well as mass production of gallium oxide materials. Its efficiency and high performance have been widely recognized in the industry. It successfully mass-produced 4-inch gallium oxide wafers in 2021 and has started supplying customer wafers, once again keeping Japan ahead in the third-generation compound semiconductor competition. According to NCT's prediction, the market for gallium oxide wafers will grow rapidly in the next decade and expand to approximately RMB 3.02 billion by 2030. FLOSFIA predicts that by 2025, the market size of gallium oxide power devices will begin to surpass that of gallium nitride, reaching 1.542 billion US dollars (approximately 10 billion RMB) by 2030, accounting for 40% of silicon carbide and 1.56 times that of gallium nitride. According to the prediction of Fuji Economy, the market size of gallium oxide power components will reach 154.2 billion yen (approximately 9.276 billion yuan) by 2030, surpassing the market size of gallium nitride power components. This trend reflects the importance and future potential of gallium oxide in power electronic devices. Gallium oxide has significant advantages in certain specific application fields. In the field of power electronics, gallium oxide power devices partially overlap with gallium nitride and silicon carbide. In the military field, they are mainly used in power control systems such as high-power electromagnetic guns, tanks, fighter jets, and ships, as well as radiation resistant and high-temperature resistant aerospace power supplies. The civilian sector is mainly applied in fields such as power grids, electric traction, photovoltaics, electric vehicles, household appliances, medical equipment, and consumer electronics.      The new energy vehicle market also provides a huge application scenario for gallium oxide. However, in China, the power devices at the vehicle level have always been weak, and there is currently no SiC MOS IDM at the vehicle level. Although several Fabless companies that contract with XFab can quickly have comprehensive SBD and MOS specifications to market, and sales and financing progress is relatively smooth, in the future, they still need to build their own FAB to master production capacity and develop unique processes, in order to generate differentiated competitive advantages. Charging stations are very cost sensitive, which provides an opportunity for gallium oxide. If     If gallium oxide can meet or even exceed performance requirements while gaining market recognition with cost advantages, there is a great possibility of its application in this field. In the RF device market, the market capacity of gallium oxide can refer to the market of silicon carbide epitaxial gallium nitride devices. The core of new energy vehicles is the inverter, which has very high requirements for device specifications. Currently, companies such as Italy Semiconductor, Hitachi, Ansemy, and Rohm are able to mass produce and supply automotive grade SiC MOSFETs. It is expected that by 2026, this number will increase to $2.222 billion (approximately 15 billion RMB), indicating that gallium oxide has broad application prospects and market potential in the RF device market.      Another important application in the field of power electronics is 48V batteries. With the widespread use of lithium batteries, a higher voltage system can be used to replace the 12V voltage system of lead batteries, achieving the goals of high efficiency, weight reduction, and energy conservation. These lithium battery systems will widely use 48V voltage, and for electronic power systems, high-efficiency 48V → 12V/5V conversion is required. Taking the two wheeled electric vehicle market as an example, according to data from 2020, the overall production of electric two wheeled vehicles in China was 48.34 million units, a year-on-year increase of 27.2%, and the penetration rate of lithium batteries exceeded 16%. Faced with such a market, 100V high-voltage high current devices such as gallium oxide, GaN, and silicon based SG-MOS devices are targeting this application and making efforts.      In the industrial field, it has several major opportunities and advantages, including unipolar replacement of bipolar, higher energy efficiency, ease of mass production, and reliability requirements. These characteristics make gallium oxide potentially play an important role in future power applications. In the long run, gallium oxide power devices are expected to play a role in the 650V/1200V/1700V/3300V market, and are expected to fully penetrate the automotive and electrical equipment fields from 2025 to 2030. In the short term, gallium oxide power devices will first appear in fields such as consumer electronics, home appliances, and highly reliable and high-performance industrial power supplies. These characteristics may lead to competition between materials such as silicon (Si), silicon carbide (SiC), and gallium nitride (GaN).      The author believes that the focus of competition for gallium oxide in the next few years will be on the conventional use of 650V devices on the 400V platform. The competition in this field will involve multiple factors such as switching frequency, energy loss, chip cost, system cost, and reliability. However, with the advancement of technology, the platform may be upgraded to 800V, which will require the use of 1200V or 1700V devices, which is already an advantage area for SiC and Ga2O3. In this competition, startups have the opportunity to establish scenario awareness, vehicle regulation system, and customer mentality through in-depth communication with customers, laying a solid foundation for the application of inverters to automotive enterprise customers.     Overall, gallium oxide has great potential in the field of power devices and can compete with materials such as SiC and GaN in multiple fields to meet the needs of high-performance applications such as high efficiency, low energy consumption, high frequency, and high temperature. However, the penetration of new materials in applications such as inverters and chargers takes time and requires continuous development of suitable specifications for specific applications, gradually promoting them to the market.

      01 Hebei Tongguang Semiconductor Co., Ltd At present, the commonly used technology for synthesizing high-purity silicon carbide powder mainly adopts high-temperature solid-state synthesis of high-purity silicon powder and high-purity carbon powder, namely self-propagating high-temperature synthesis. To solve the problem of high nitrogen impurity concentration in traditional self-propagating synthesis of SiC powder, Hebei Tongguang Semiconductor Co., Ltd. has invented a low nitrogen impurity concentration silicon carbide powder synthesis method that can be used for the growth of high-purity semi insulating SiC single crystals. This method uses nitrogen removal substances that undergo chemical reactions with nitrogen elements at high temperatures. The formed nitrides exist in a stable form within the temperature range of silicon carbide synthesis, effectively avoiding nitrogen impurities from entering the silicon carbide lattice. It breaks through the current traditional synthesis method of silicon carbide raw materials and achieves the synthesis of low nitrogen content silicon carbide raw materials, with a nitrogen content below 2 × 1016 pieces/cm3, which is particularly suitable for the growth of high-purity semi insulating SiC single crystals. At present, the most effective method for growing SiC crystals is the Physical Vapor Transport (PVT) method, and the crystals formed in sublimation systems have lower defect levels, making them the main commercial mass production technology. When using PVT method to grow SiC crystals, the growth equipment, graphite components, and insulation materials cannot avoid being contaminated by nitrogen impurities. These materials will adsorb a large amount of nitrogen impurities, resulting in a high content of nitrogen impurities in the SiC crystals grown. At present, the purity of high-purity SiC powder raw materials produced commercially can generally only reach 99.999%, with a nitrogen content of mostly 5% × A level of over 1016 units/cm3 seriously affects the nitrogen content in its subsequent product - high-purity semi insulating silicon carbide single crystals. Therefore, reducing the nitrogen impurity content in powder raw materials is of great significance for the preparation of high-purity semi insulating silicon carbide crystals. Below, based on the patent information of several well-known enterprises disclosed by Tianyancha, relevant technologies for the preparation of high-purity silicon carbide powder are introduced.   This method includes the following steps: (1) Mix the silicon raw material and carbon raw material thoroughly; (2) Add nitrogen removal substances to the mixture of silicon raw materials and carbon raw materials, and then place the crucible containing nitrogen removal substances and carbon silicon mixture raw materials in the reaction chamber; The crucible material is high-purity graphite, with a purity of over 99.9995%; (3) Vacuum the reaction chamber to reduce the content of oxygen and nitrogen in the reaction chamber; (4) Heat the reaction chamber, raise the temperature, and cause the nitrogen removal substance to react with the nitrogen element, forming a solid or gas form of nitride that will not decompose below 2400 ℃; (5) Inject inert gas into the reaction chamber, maintain the pressure of the reaction chamber, gradually increase the temperature of the reaction chamber, cause the carbon raw material and silicon raw material to react, gradually cool to room temperature, and end the reaction; (6) Remove the nitride from the obtained silicon carbide to obtain low nitrogen content silicon carbide raw material.   02 Beijing Tankblue Semiconductor Co., Ltd Tianke Heda has invented a preparation method for low nitrogen content silicon carbide powder and silicon carbide single crystal. The preparation method includes the following steps: mixing high-purity silicon powder, high-purity graphite powder, and volatile high-purity organic matter, and letting the volatile high-purity organic matter evaporate to less than 10% of the initial mass under an inert atmosphere. The mixed material is sintered to obtain low nitrogen content silicon carbide powder. The invention uses volatile and high-purity organic compounds to remove nitrogen from the surface of raw materials and grain boundaries during the preparation of silicon carbide powder, thereby reducing the nitrogen content in the product. The experimental results show that the nitrogen content of silicon carbide powder and single crystal is less than 5 × 1016 pieces/cm3.   03 Zhongdian Compound Semiconductor Co., Ltd Zhongdian Compound Semiconductor Co., Ltd. has invented a synthesis method for silicon carbide powder, which includes: mixing high-purity carbon powder and high-purity silicon powder, and loading them into a graphite crucible. The graphite crucible is lined with fluorinated graphite, and the graphite crucible is placed in the furnace cavity; Raise the temperature of the furnace chamber, and during the heating process, a mixture of hydrogen and inert gas is introduced into the furnace chamber, and the fluorinated graphite lining decomposes to release fluorinated gas; Extract the gas from the furnace chamber, causing the high-purity carbon powder to react with the high-purity silicon powder to obtain intermediate products; Raise the temperature of the furnace chamber to cause the intermediate phase products to react and generate silicon carbide powder. By providing a method for synthesizing silicon carbide powder, high-purity silicon carbide powder can be obtained. 04 Shandong  SICC Advanced Technology Co., Ltd Tianyue Advanced has invented a device and method for preparing silicon carbide powder, which includes: a furnace body, with a partition board installed inside the furnace body. When the partition board is closed, the part inside the furnace body is divided into two parts; When the partition is opened, the furnace body is internally connected; The surface of the electrode is at least partially covered with carbon source raw materials; Crucible, placed inside the furnace body; The crucible and electrode undergo relative displacement to allow the electrode to enter or leave the crucible. During the melting process of silicon source raw materials, a partition is used to separate the silicon source raw materials and carbonization raw materials in the furnace, avoiding the evaporation of silicon liquid during heating and crystallization at the carbonization raw materials, which affects the growth of powder and improves the quality of powder growth. This method can prevent the evaporation of silicon liquid during the melting process of silicon source raw materials and crystallization at the carbonized raw materials by controlling the opening or closing of the partition, resulting in low nitrogen impurity content and other impurity content in the obtained powder. It can be used for the preparation of high-purity silicon carbide crystals.