With the outbreak of downstream new energy vehicles, charging piles, photovoltaic, 5G base stations, detonated a huge market demand for third-generation semiconductor-silicon carbide materials, epitaxial and devices, and many companies have passed strengthening technology. R & D and capital investment layout silicon carbide industry, today we first explore the localization process of silicon carbide substrates.
◆ Silicon carbide substrate type
Carbide is divided into cubic phase (flash zinc mine structure), six-square phase (fiber zinc mine structure) and the three categories of Linger phase have a total of more than 260 structures. At present, only the 4h-SiC, 6h-SiC in the six-party phase is commercialized. value. Another silicon carbide can be divided into electrically conductive silicon carbide lining of semi-insulating silicon carbide substrate and low resistance (15 to 30 mΩ · cm) of low resistance (15 to 30 mΩ · cm) of high resistance (resistivity range of 15 to 30 mΩ · cm) according to different electrical properties. At the end, meet different functional chip requirements, where:
The semi-insulating silicon carbide substrate is mainly used to produce a gallium gallium gallium gallium radical device. By growth of gallium nitride epitaxial layers on the semi-insulating silicon carbide substrate, the silicon carbide-based gallium nitride epitaxial sheet can be further formed into a gallium nitride rafting device;
Conductive silicon carbide substrates are mainly used in manufacturing power devices. Unlike traditional silicon power devices, silicon carbide power devices cannot be directly produced on silicon carbide substrates, which require silicon carbide epitaxial layer to produce silicon carbide epitaxial sheets, and produce various power on the epitaxial layer. Device.
Large sized silicon carbide substrates helps achieve significant increase in efficacy, has become mainstream development trends. The larger the substrate size, the unit substrate can produce more chips, so the lower the unit chip cost, and the reduction in edge waste will further reduce the production cost of the chip. At present, the silicon carbide substrate of industry enterprise mass production is mainly 4 inches and 6 inches, in the semi-insulated silicon carbide market, current substrate specifications are 4 inches; in the conductive silicon carbide market, current mainstream lining The base product is 6 inches. International giants CREE, II-VI and Domestic Splendom crystals have successfully developed 8 inch substrate products.
◆ Silicon carbide single crystal preparation technology
Silicon carbide substrate preparation techniques include PVT method (physical gas phase transfer method), solution method and HTCVD method (high temperature gas phase chemical deposition method), etc. At present, the silicon carbide single crystal is prepared by PVT method in the international basis. The SiC single crystal growth experienced three stages, namely the Acheson method, the LELY method, and the improved LELY method.
Using the SiC high temperature sublimation decomposition characteristics, it can be used to grow SiC crystals, which is between the SiC powder is placed between graphite crucible and porous graphite tube, at the inert gas (argon) ambient temperature of 2 500 ° C The sublimation growth can be produced under conditions, and a sheet-like SiC crystal can be generated.
However, the LELY method is a self-erate-growing method, which is difficult to control the crystal shape of the growth SiC crystal, and the obtained crystal size is small, and there is a modified LELY method, that is, the PVT method (physical gas phase transfer method), its advantages The crystal shape of the growth crystals of SiC seed crystal is used to overcome the shortcomings of the LELY method spontaneously nucleated growth, and a single crystal SiC single crystal can be obtained, and a large size SiC single crystal can be obtained.
◆ Why is the semi-insulated type and conductive silicon carbide substrate technology barrier?
In the PVT method, the purity of SiC powder has a greater impact on the wafer quality. The powder contains very small amounts of nitrogen (N), boron (B), aluminum (Al), iron (F e), and the like, wherein nitrogen is an N-type dopant, producing free electrons, boron, boron in silicon carbide. Aluminum is a p-type dopant to produce a free hole.
In order to prepare an N-type conductive silicon carbide wafer, nitrogen is required to be introduced when grown, allowing it to produce a portion of the electron and an aluminum, aluminum, aluminum, and additional free electron silicon carbide as an n-type conductive. .
In order to prepare high-resistant non-conductive silicon carbide (semi-insulating type), vanadium (V) impurities need to be added during growth, and vanadium can produce electrons, or generate holes, which make it produced in electrons and boron, aluminum production The hole (ie, compensation), which produces the electron generated in the hole and the nitrogen generated electron, so the growth of silicon carbide has almost no free electron, holes, forming a high-resistant non-conductive wafer (semi-insulating type).
The vanadium doped process is complex, so the semi-insulating silicon carbide is difficult to prepare, and the cost is high. In recent years, a method of achieving high-resistance semi-insulating silicon carbide has occurred. P-type conductive silicon carbide is also not easy to prepare, especially low-resistant p-type silicon carbide is not easily prepared.
◆ The downstream market demand is strong, the silicon carbide substrate market ushered in gold growth period
In terms of conductive silicon carbide substrate, it is benefited from the huge demand for new energy vehicle inverters. It will maintain a high-speed growth situation. According to the data of China's CHFP Power Semiconductor and Application Industry Alliance, it is expected that demand in the domestic market in 2020-2025. 4 inches gradually decreased from 100,000 pieces from 100,000 pieces, 6 inch wafers will grow from 80,000 pieces to 200,000 pieces; 2025 ~ 2030: 4-inch wafers will gradually withdraw from the market, 6 inch wafers will grow To 400,000 pieces.
Semi-insulated silicon carbide substrate, is driven by the downstream 5G base station, the silicon carbide-based gallium high-frequency radio frequency device will gradually strengthen the market penetration, the market space is broad, expected to demand in the domestic market in 2020-2025, 4 inches gradually From the 50,000 tablets, the 6-inch wafer will increase from 50,000 pieces to 100,000 pieces; 2025 ~ 2030: 4-inch wafer will gradually exit the market, the conservative estimate of 6 inch wafers will grow to 20 10,000 pieces.
◆ Silicon carbide substrate localization process speed speed
Global silicon-silicon substrates have mainly Cree, II-VI, Sirystal, International Leaders, which have leads in domestic enterprises, with leading advantages in industrial experience, technical maturity, capacity, etc., seizes global silicon carbide Most of the market share of the substrate.
With the rapid growth of the downstream terminal market, new energy vehicles, photovoltaic, 5G base station and other fields, providing huge market vitality for the upstream silicon carbide substrate, representing Shandong Tianyue, Tianke He Da, Softjing Crystals The enterprises have running the horn-rated silicon carbide substrate market, through strengthening technology research and development and capital investment, gradually grasping 4 inches to 6 inches, or even 8 inch silicon carbide substrate manufacturing technology, narrowing technology and capacity between international faucets Aspects of gaps.
EDTOR: JQ, Original Title: China's China Silicon Substrate
Article Source: [Micro Signal: MCU168, WeChat public number: Hardware siege] Welcome to add attention! Please indicate the source of the article.
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