Aluminum nitride ceramics are an advanced ceramic material with aluminum nitride (AlN) as the main crystal phase. It has many excellent properties: in terms of physics, it has high thermal conductivity, can effectively dissipate heat, has excellent electrical insulation performance, can avoid circuit interference, and its thermal expansion coefficient matches well with semiconductor materials; in terms of chemistry, it has high chemical stability and excellent oxidation resistance and can remain stable in corrosive environments such as acids and alkalis and high-temperature oxidizing atmospheres; in terms of mechanical properties, it has high hardness and strength, and its bending strength can reach more than 900 MPa. It also has good thermal shock resistance and can withstand drastic changes in temperature. Based on these characteristics, aluminum nitride ceramics are widely used in electronics, optics, machinery, the chemical industry, biomedicine, and other fields, such as making integrated circuit substrates, LED substrates, wear-resistant parts, corrosion-resistant containers, biosensors, etc. It is one of the important materials to promote the development of modern science and technology.

Physical properties of aluminum nitride ceramics

Appearance: White or off-white, single crystals are colorless and transparent.

Density: The density is 3.3 g/cm³, which is lower than most ceramics.
Melting point and boiling point: The melting point is 2200°C, the boiling point is 2517°C, and it has high heat resistance.

High thermal conductivity: The thermal conductivity can reach 260 W/(m?K), which is 5-8 times higher than alumina and close to BeO and SiC. It is one of the ceramic materials with higher thermal conductivity, so it has good thermal shock resistance and can withstand extreme heat of 2200°C.

Low thermal expansion coefficient: The thermal expansion coefficient is (4.0-6.0)×10??/?, which matches well with Si (3.5-4×10??/?) and GaAs (6×10??/?). When the temperature changes, its size changes less, which helps to maintain the stability of thermal conduction.

Optical transmission characteristics: The optical transmission characteristics are good and can be used to manufacture optical components such as infrared windows.

Chemical properties of aluminum nitride ceramics

Good chemical stability: aluminum nitride ceramics have good chemical stability, good resistance to moisture and many chemicals, can maintain stability in a variety of chemical environments, can maintain stability in corrosive environments such as acids and alkalis and high-temperature oxidizing atmospheres, and reduce corrosion and degradation.

Strong oxidation resistance: At high temperatures, a dense oxide film will form on the surface of aluminum nitride ceramics to prevent further oxidation, so it has good oxidation resistance.

Resistance to molten metal corrosion: aluminum nitride ceramics are not corroded by aluminum liquid and other molten metals and gallium arsenide, especially molten aluminum liquid. It has excellent corrosion resistance and can be used as crucibles and casting mold materials for smelting metals such as aluminum, copper, silver, and lead.

Electrical properties of aluminum nitride ceramics

Excellent electrical insulation performance: The electrical insulation strength can reach 10¹?Ω?cm, making it an ideal insulating material in electronic components, and it can maintain stable electrical properties under high-temperature and high-frequency environments.

Good dielectric properties: Relatively high dielectric constant, 8.8-8.9 (pure AlN), which is similar to the dielectric constant of Al?O?, but much lower than SiC, and has low dielectric loss, which can be used in high-frequency circuit applications. In addition, AlN also shows piezoelectricity, which is useful in thin film applications.

Aluminum nitride ceramics have a wide range of applications in the semiconductor field, mainly including the following aspects:

Semiconductor manufacturing equipment

• Heater
  Aluminum nitride ceramic heaters have become an indispensable component in the semiconductor manufacturing process due to their high thermal conductivity, low thermal expansion coefficient, and good electrical insulation properties. Especially in chemical vapor deposition (CVD) equipment, aluminum nitride heaters can provide uniform temperature distribution, ensure the temperature stability of wafers during processing, and thereby improve production efficiency and product quality.

• Electrostatic chuck
  Electrostatic chuck (ESC) is a key component used to fix and control the temperature of wafers in the semiconductor manufacturing process. Aluminum nitride has become an ideal material for making the dielectric layer of electrostatic chucks due to its high thermal conductivity and good electrical insulation properties. Aluminum nitride electrostatic chucks can ensure the temperature uniformity and surface flatness of the wafer during processing and improve the stability and yield of the process.

• Precision ceramic parts
  Aluminum nitride ceramic parts are widely used in semiconductor equipment. For example, Zhongci Electronics has developed alumina and aluminum nitride core materials and supporting metallization systems for precision ceramic parts and established a complete precision ceramic parts manufacturing process platform. These parts have excellent properties such as high strength, corrosion resistance, and high precision and are used in semiconductor key equipment such as etchers, glue developers, and ion implanters.

Semiconductor packaging

• Ceramic substrates
  Aluminum nitride ceramic substrates are ideal for high-performance electronic packaging. Its high thermal conductivity and low thermal expansion coefficient enable it to effectively dissipate heat, reduce thermal stress, and improve the reliability and life of packaged devices. Aluminum nitride substrates are widely used in high-power semiconductor devices, LED packaging, communication devices, and other fields.

• Package shell
  Aluminum nitride ceramics have good airtightness and electrical insulation properties and can be used to manufacture semiconductor package shells. The package shell can protect the semiconductor chip from the influence of the external environment and improve the reliability and stability of the chip.

Semiconductor materials

• Substrate materials
  Aluminum nitride crystals are ideal substrates for GaN, AlGaN, and AlN epitaxial materials. Compared with sapphire or SiC substrates, AlN has higher thermal matching and chemical compatibility with GaN and less stress between the substrate and the epitaxial layer. Therefore, when AlN crystals are used as GaN epitaxial substrates, they can significantly reduce the defect density in the device and improve the performance of the device. They have good application prospects in the preparation of high-temperature, high-frequency, and high-power electronic devices.

• Thin film materials
  Due to the wide band gap, strong polarization, and bandgap width of 6.2 eV, the aluminum nitride thin film materials prepared by AlN have many excellent physical and chemical properties, such as high breakdown field strength, high thermal conductivity, high resistivity, high chemical and thermal stability, and good optical and mechanical properties. They are widely used as isolation media and insulating materials in the packaging of electronic devices and integrated circuits.