In the booming semiconductor industry, all kinds of materials are crucial. Graphite may seem ordinary, but it is indispensable in semiconductor production with its unique properties, from characteristics to applications, to promote technological progress.
Is graphite a semiconductor?
No, it isn’t. The conductivity of semiconductors is between conductors and insulators, and their electrical properties are greatly affected by temperature and impurities. And they have a unique band structure, which can greatly change the conductive properties by doping. Although graphite conducts electricity well, its crystals are arranged in hexagonal layers and conduct electricity by delocalized large π bonds. There is no band structure that can be precisely regulated, and electrical properties cannot be significantly changed by conventional doping. So it is not a semiconductor, but a special carbon material.
Basic properties of graphite
Propiedades físicas
Crystal structure
Graphite has a typical layered crystal structure. Each layer of carbon atoms is arranged in a hexagonal dense two-dimensional plane network. And the carbon in the plane is connected by covalent bonds, the bond length is about 0.142nm, the bond Angle is 120°. And the layer is acted on by weak van der Waals force, which gives the graphite unique physical properties.
Density and hardness
Its density is about 2.09-2.23g /cm³, which has advantages in scenarios where weight is required. The Mohs hardness is only 1-2, and the texture is soft. And the layers are easy to slide relatively under the action of external forces.
Propiedades químicas
Estabilidad química
Under normal temperature and pressure, it has excellent chemical stability. It is not easy to react with common reagents, and can maintain stable structure and performance in harsh chemical environment. This is due to the covalent bond structure between carbon atoms, which can resist most conventional chemical attacks.
Reaction characteristics with common semiconductor production reagents
Strong oxidizing or corrosive reagents such as hydrofluoric acid and nitric acid are commonly used in semiconductor production. In general, it does not react significantly with these reagents, such as almost no effect with hydrofluoric acid. And it can maintain the structural integrity and function of the production equipment.
Application of graphite in all aspects of semiconductor production
Wafer fabrication
In the wafer manufacturing process, you can mainly use it for heating and support systems. Wafer growth requires precise temperature control, graphite heaters with its good electrical and thermal conductivity. It can quickly and evenly convert electrical energy into heat, providing a stable high temperature environment for wafer growth. The support parts made of graphite can withstand high temperatures, ensure the stability of the wafer during the growth process. And help improve the quality of the wafer and production efficiency.
Photolithography
Photolithography is a crucial step in semiconductor manufacturing, requiring high-precision positioning and a stable working environment. You can use graphite materials to manufacture the bearing platform and some key components in lithography equipment. Because of its good mechanical stability and low thermal expansion coefficient. In the process of lithography, it can guarantee the relative position accuracy between the lithography mask and the wafer. And reduce the lithography error caused by thermal expansion and cold contraction, to improve the resolution and accuracy of lithography.
Etching and deposition
In the etching and deposition process, graphite also plays an important role. In the etching process, the high-purity graphite electrode is used in the etching machine. It can produce a stable plasma under the action of an electric field, carry out precise etching of semiconductor materials. In the deposition process, the graphite base is used for chemical vapor deposition (CVD) and other processes. To provide a stable support and reaction environment for the growth of the film. Its high temperature stability and chemical inertness enable it to maintain stable performance during these high temperature, high energy processes. And ensuring the quality and uniformity of etching and deposition.
Graphite parts in semiconductor manufacturing
Graphite heater
The graphite heater is commonly used in semiconductor manufacturing heating elements. It has low resistance, fast heating, can reach high temperature in a short time, uniform temperature distribution. In wafer annealing, epitaxial growth and other processes requiring rapid heating and precise temperature control, it can meet the harsh temperature requirements. And it ensures the optimization of semiconductor material properties.
Graphite Crucible (monocrystalline silicon)
Graphite crucible is widely used in monocrystalline silicon production. Monocrystalline silicon growth needs high temperature pure environment, it has high temperature resistance and good chemical stability. It will not pollute monocrystalline silicon. Moreover, it has good heat conduction and uniform heat transfer, which helps the stable growth of monocrystalline silicon and improves the quality and yield.
Graphite Base (CVD)
In chemical vapor deposition (CVD) process, it is the key. It provides a stable surface for the gas phase reaction and facilitates the reaction of gaseous reactants into films. Its surface flatness and thermal stability are related to the quality and uniformity of the film. And good thermal conductivity ensures that the surface temperature of the base is uniform and the quality of the film is consistent.
High purity graphite electrode (etching machine)
In the etching machine, you can use this to generate plasma to achieve precise etching of semiconductor materials. It has good electrical conductivity and corrosion resistance, can work stably in high voltage, strong electric field and corrosive gas environment. Its high purity can avoid the introduction of impurities during etching, to ensure the etching accuracy and device performance.
Graphite molds for sintering (electronic devices)
A large number of graphite molds are used for sintering electronic devices. It has good machining performance and can be customized according to different electronic device shapes. High strength and stability at high temperature, can withstand high temperature and high pressure during sintering. It ensures the shape and size accuracy of electronic devices in sintering, promote the internal material tight bonding. And it improves device performance and reliability.
Advantages of graphite materials
Excelente resistencia a altas temperaturas
The melting point of graphite reaches 3652-3697 ℃, which can withstand the extreme temperature of the semiconductor production high temperature process. It can maintain the structure stability, and provide a reliable guarantee for high temperature treatment.
Good electrical and thermal conductivity
It has good electrical conductivity, can quickly conduct current and generate plasma. Good thermal conductivity, rapid heat transfer, conducive to improving the precision and efficiency of semiconductor production process temperature control.
Mechanical stability and processing performance
It has soft texture but good mechanical stability at high temperature, can be used normally. The processing performance is good, and you can make it to various parts by cutting and other processes to meet the production needs.
Semiconductor graphite materials market status
With the vigorous development of the semiconductor industry, the demand for semiconductor graphite materials continues to rise. And the global market is steadily rising. Internationally renowned material enterprises with technology and production capacity advantages, occupy a large share. Domestic enterprises are also increasing research and development investment, enhance competitiveness. Semiconductor technology is moving toward high-precision, large-size wafers, which require higher performance of graphite materials. And driving suppliers to continue to innovate and upgrade products.
Conclusión
Graphite is not a semiconductor, but by virtue of its unique physical and chemical properties, it plays a great role in all aspects of semiconductor production. Its high temperature resistance, good electrical and thermal conductivity, mechanical stability and good processing performance, is an indispensable material for production.
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