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June 19, 2024

Application of aluminum nitride in the semiconductor field

01 Substrate materials and packaging materials

With the vigorous development of microelectronics and semiconductor technology, current-power semiconductor devices need to have high voltage, high current, high power density, small size, and other characteristics at the same time. The heat flow density of electronic substrates has increased significantly, and maintaining a stable operating environment inside the equipment has become a focus. Technical issues of concern. For this reason, substrate materials in power-integrated circuits must have both good mechanical reliability and high thermal conductivity. At present, packaging substrate materials mainly use alumina ceramics or polymer materials. However, as the requirements for carrier substrates for electronic parts become more and more stringent, their thermal conductivity cannot meet the needs of the industry. AlN ceramics have thermal conductivity It has the characteristics of high thermal expansion coefficient, close to the thermal expansion coefficient of silicon, high mechanical strength, good chemical stability and environmental protection, and non-toxicity. It is considered to be an ideal material for the new generation of heat-dissipation substrates and electronic device packaging. Compared with the Al2O3 ceramic substrate and Si3N4 ceramic substrate, the AlN ceramic substrate has these advantages: using the AlN ceramic substrate as the carrier of the chip can isolate the chip from the module heat dissipation bottom plate, and the AlN ceramic layer in the middle of the substrate can effectively improve the insulation capability of the module. (Ceramic layer insulation withstands voltage >2.5KV), and the aluminum nitride ceramic substrate has good thermal conductivity, and the thermal conductivity can reach 170-260W/mK. In addition, the expansion coefficient of the AlN ceramic substrate is similar to that of silicon, which will not cause stress damage to the chip. The peeling resistance of the AlN ceramic substrate is >20N/mm2. It has excellent mechanical properties, and corrosion resistance, and is not prone to deformation. It can be used in a wide range of applications. Use within temperature range.

AlN BN Ceramic 24052

02 Electrostatic chuck for wafer processing

The wafer processing process in modern semiconductor manufacturing processes involves multiple processes. The wafers need to be transferred back and forth between hundreds of process equipment, so a device is needed to clamp the wafers. The electrostatic chuck can fix the wafer through electrostatic adsorption. The adsorption force is uniform and stable. The wafer will not warp and deform, ensuring the processing accuracy and cleanliness of the wafer. The current common electrostatic chuck technology mainly uses alumina ceramics or aluminum nitride ceramics as the main material. For ordinary silicon wafer processing, high-purity alumina or sapphire can meet the requirements. However, if used in silicon carbide wafer processing, the thermal conductivity is insufficient, and aluminum nitride must be used to meet the requirements.

The advantage of the aluminum nitride ceramic electrostatic chuck is that it can obtain a wide temperature range and sufficient adsorption force by controlling its volume resistivity. The electrostatic chuck can achieve good temperature uniformity through a heater design with a high degree of freedom; Nitrogen Aluminum is integrally co-fired and will not undergo changes over time due to electrode degradation, ensuring product quality to the greatest extent; it can operate for a long time in a plasma halogen vacuum atmosphere to withstand the most demanding process environments of semiconductors and microelectronics. It also provides stable adsorption and temperature control.

03 Substrate material

AlN crystal is an ideal substrate for GaN, AlGaN, and AlN epitaxial materials. Compared with sapphire or SiC substrates, AlN and GaN have higher thermal matching and chemical compatibility, and less stress between the substrate and the epitaxial layer. Therefore, when AlN crystal is used as a GaN epitaxial substrate, it can greatly reduce the defect density in the device, improve the performance of the device, and have good application prospects in the preparation of high-temperature, high-frequency, and high-power electronic devices. In addition, using AlN crystal as an AlGaN epitaxial material substrate with a high aluminum (Al) component can also effectively reduce the defect density in the nitride epitaxial layer and greatly improve the performance and service life of nitride semiconductor devices. High-quality solar blind detectors based on AlGaN have been successfully used.

04 Thin film materials

Due to AlN’s wide band gap, strong polarization, and bandgap width of 6.2eV, the aluminum nitride thin film material prepared by it has many excellent physical and chemical properties, such as high breakdown field strength, high thermal conductivity, high resistivity, and high Due to its chemical and thermal stability, as well as good optical and mechanical properties, it is widely used as an isolation medium and insulating material in the packaging of electronic devices and integrated circuits. The high-quality AlN film also has the characteristics of extremely high ultrasonic transmission speed, small acoustic wave loss, considerable piezoelectric coupling constant, and thermal expansion coefficient similar to Si and GaAs. Its unique properties make it widely used in machinery, and microelectronics, There are broad application prospects in the fields of optical and electronic components, surface acoustic wave device manufacturing, and high-frequency broadband communications. At present, the preparation of aluminum nitride thin films is still at a stage where the equipment is complex, expensive, and difficult to commercialize, and the method used to prepare the thin films usually requires heating the substrate to a relatively high temperature. At present, the method of preparing aluminum nitride thin films at low temperatures is not mature and perfect. The development of integrated optical devices requires thin film preparation at lower temperatures to avoid thermal damage to the substrate material. There is still a lot of work to be done to improve the preparation method of aluminum nitride films and obtain denser, more uniform, higher purity, and lower-cost aluminum nitride films at lower temperatures and simpler process conditions.

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