Tantalum carbide ceramics-a key material for semiconductor equipment and aerospace

tantalum carbide ceramic-Key materials in the field of semiconductor equipment and aerospace

Recently, Hengpu Technology launched a new kind of technology in the official microSiCCrystal growth thermal field material-porous tantalum carbide, it is introduced that the material is conducive to the control of defects in the process of crystal growth.

What kind of material is tantalum carbide?

Tantalum carbide (TaC) is an ultra-high temperature ceramic material, the so-called ultra-high temperature ceramic (UHTCs) usually means that the melting point exceeds3000C, and in2000A class of ceramic materials used in high temperatures above °C and corrosive environments (e. g., oxygen-atom environments), suchZrC,HfC,TaC,HfB2,ZrB2,HfNWait.

TaCNature

The melting point of tantalum carbide is as high3880℃, with high hardness (Mohs hardness9~10), larger thermal conductivity (22W·m-1·K-1), large bending strength (340~400MPa), and a smaller coefficient of thermal expansion (6.6×10-6K-1), and exhibits excellent thermochemical stability and excellent physical properties, with graphite andC/CComposite materials have good chemical compatibility and mechanical compatibility, soTaCCoatings are widely used in aerospace thermal protection, single crystal growth, energy electronics, and medical devices.

Applied to semiconductor equipment

At present, the wide band gap semiconductor represented by silicon carbide is a strategic industry facing the main economic battlefield and the major needs of the country. At the same time, silicon carbide semiconductor is an industry with complex process and high equipment requirements. Among them, the preparation of silicon carbide single crystal is the most basic and important link of the entire industrial chain.

CurrentlySiCThe most commonly used method of crystal growth is the physical vapor transport method (PVTlaw),PVTmethod by means of induction heating within a closed growth chamber2300°CThe above high temperature, close to vacuum low pressure heating silicon carbide powder, so that its sublimation to produce containing.Si,Si2C,SiC2The reaction gas of different gas phase components is passed through the solid.-The gas reaction produces a silicon carbide single crystal reaction source, a silicon carbide seed crystal (seed) is set at the top of the growth chamber, and the gas phase component transported to the seed crystal is atomically deposited on the surface of the seed crystal driven by the supersaturation of the gas phase component, and grows into a silicon carbide single crystal.

The process has long growth cycle, difficult to control, easy to produce microtubules, inclusions and other defects. For the control of defects, the slight adjustment or drift of the thermal field in the furnace will bring about the change of crystal or the increase of defects. More to face laterIn addition to the improvement of theory and engineering, the challenge of "growing fast, growing thick and growing up" also needs more advanced thermal field materials as support.

The materials of the crucible in the thermal field are mainly graphite and porous graphite. However, graphite is easily oxidized when exposed to oxygen at high temperature, and will be corroded by molten metal.TaCIt has excellent thermochemical stability and excellent physical properties, and has good chemical compatibility and mechanical compatibility with graphite, and is prepared on the surface of graphite.TaCThe coating can effectively enhance its oxidation resistance, corrosion resistance, wear resistance and mechanical properties. especially suitableMOCVDEquipment growthGaNorAlNsingle crystal andPVTEquipment growthSiCThe quality of the grown single crystal is significantly improved.

In addition, the silicon carbide single crystal preparation process, through the solid.-After the gas reaction produces the silicon carbide single crystal reaction source,Yes/CThe stoichiometric ratio varies with the distribution of the thermal field, the gas phase components need to be distributed and transmitted according to the designed thermal field and temperature ladder, the air permeability of porous graphite is not enough, additional openings are needed to increase the air permeability, and the porous graphite with large air permeability is faced with processing, powder dropping, etching and other challenges. Porous tantalum carbide ceramics can better realize the gas phase component filtration, adjust the local temperature gradient, guide the direction of material flow, control leakage and so on.

DueTaCcoating pairH2,HCl,NH3With excellent acid and alkali resistance, in the silicon carbide semiconductor industry chain,TaCAlso available inMOCVDIn the process of epitaxial treatment, the graphite substrate material is completely protected and the growth environment is purified.

application in aerospace

With the development of modern aircraft such as aerospace vehicles, rockets and missiles towards high speed, high thrust and high altitude, the requirements for high temperature resistance and oxidation resistance of surface materials under extreme conditions are getting higher and higher. When the aircraft enters the atmosphere, it faces extreme environments such as high heat flux, high stagnation pressure and fast airflow scouring speed, as well as chemical ablation caused by reaction with oxygen, water vapor and carbon dioxide. When the aircraft flies out and into the atmosphere, the air around its nose cone and wing will be severely compressed and produce greater friction with the surface of the aircraft, causing its surface to be heated by the airflow. In addition to the aerodynamic heating of the aircraft surface during flight, it will also be affected by solar radiation and environmental radiation during flight, which will cause the surface temperature of the aircraft to rise continuously. This change will seriously affect the service status of the aircraft.

TaCIt is a member of the ultra-high temperature resistant ceramic family, with high melting point and excellent thermodynamic stability.TaCIt is widely used in the hot end of aircraft, for example, it can protect the surface coating of rocket engine nozzle.

Other Applications

TaCIt also has a wide range of applications in the fields of cutting tools, abrasive materials, electronic materials and catalysts. For example, willTaCAdding in cemented carbide can prevent the grain growth of cemented carbide, improve the hardness of cemented carbide and improve its service life;TaCHas good conductivity, and can be composed of non-stoichiometric compounds, conductivity varies with the composition, this property makesTaCIt has attractive application prospects in the field of electronic materials.TaCIn terms of catalytic dehydrogenation, some researchers haveTiC,TaCThe catalytic performance of the study shows that at lower temperatures,TaCBasically no catalytic activity, but at higher1000C, the catalytic activity increased significantly. ForCOThe catalytic performance of the study found that,300℃TaCThe catalytic products are methane, water and a small amount of olefins.

In semiconductor chip equipment, the cost of precision ceramic components accounts for about10%, the current market is basically monopolized by the United States, Japan and other developed countries. How to realize the localization of advanced ceramic components in semiconductor equipment such as lithography machines and solve the current "stuck neck" problem in the chip industry is also an important part of the great opportunities and challenges faced by domestic advanced ceramic enterprises.

At the same time, with new energy vehicles,5GWith the vigorous development of industries such as artificial intelligence and the Internet of things, the scale of the third generation wide band gap semiconductor material industry represented by silicon carbide and gallium nitride continues to expand, and advanced ceramics will usher in a larger application market in the semiconductor industry.