Aluminum nitride (AlN) is a kind of integrated high performance new ceramic material, has excellent thermal conductivity, a reliable electrical insulation, low dielectric constant and dielectric loss, non-toxic and match the silicon thermal expansion coefficient, and a series of excellent features, is considered to be * * a high degree of the semiconductor substrate and the ideal of the electronics packaging materials, wide attention by the researchers at home and abroad. In theory, the thermal conductivity of AlN is 320 w/(m), industrial preparation of polycrystalline aluminum nitride on actual thermal conductivity can be up to 100 ~ 250 w/(m), This value is 5 ~10 times of the thermal conductivity of traditional substrate material alumina, which is close to the thermal conductivity of beryllium oxide. However, beryllium oxide is gradually stopped in industrial production due to its highly toxic properties. Compared with other ceramic materials, aluminum nitride ceramic has excellent comprehensive properties, and is very suitable for semiconductor substrates and structural packaging materials.
High resistivity, high thermal conductivity and low dielectric constant are the basic requirements of integrated circuits for packaging substrates. The packaging substrates should also have good thermal matching, easy to form, high surface flatness, easy metallization, easy to process, low cost and certain mechanical properties with silicon wafers. Most ceramics are ionic bond or covalent bond materials, with excellent comprehensive performance, is commonly used in electronic packaging substrate materials, with high insulation performance and excellent high-frequency characteristics, at the same time, linear expansion coefficient and electronic components are very similar, very stable chemical properties and high thermal conductivity. For a long time, most of the substrate materials of high-power hybrid integrated circuits have been using A1203 and BeO ceramics, but the thermal conductivity of A1203 substrate is low, and the thermal expansion coefficient does not match Si. Although BeO has excellent comprehensive performance, its high production cost and virulent disadvantages limit its application and popularization. Therefore, considering such factors as performance, cost and environmental protection, they cannot meet the needs of the development of modern electronic power devices.
Electronic thin film materials are the basis of microelectronics and optoelectronics, so the research of various new electronic thin film materials has become the focus of many researchers. AlN was discovered in the 1860s and can be widely used as electronic thin film material. In recent years, represented by Ⅲ A family of nitrides of wide bandgap semiconductor material and the fast development of electronic devices, known as the represented by Si * * generation and second generation represented by GaAs semiconductor after the third generation of semiconductor. A1N as typical Ⅲ A family of nitride obtained more and more the attention of the researchers at home and abroad. At present, many countries have invested a lot of manpower and material resources to research AlN films. A1N has many excellent performances, band gap width, strong polarization, band gap width of 6.2ev, which makes it have broad application prospects in the fields of mechanical, microelectronics, optics, electronic components, SAW manufacturing, high frequency broadband communication and power semiconductor devices. AlN has been widely used as piezoelectric film due to its many excellent properties. As the packaging, dielectric isolation and insulation material of electronic devices and integrated circuits, it has an important application prospect. As blue light and ultraviolet luminescence materials, it is also a research hotspot.
In order to improve the fragility of ceramic materials, many researches have been carried out. The process of adding the second and third phase particles to form the multiphase ceramic is also the best way to improve the toughness of ceramic material. Silicon carbide has been widely used in machinery, chemical industry, energy and military industry due to its high hardness, high temperature strength, abrasion resistance, corrosion resistance and low density. However, its application is limited due to its low room temperature strength and insufficient toughness. In order to improve the strength and toughness of sic ceramic materials, some achievements have been made by using the second phase particle addition method according to the theory of metal dispersion strengthening. For example, SiC/TiC, SiC/ A1203, SiC/TlB, etc.
Aluminum nitride (AlN) with high thermal conductivity, the theory of thermal conductivity of 320 w/(m • K), the actual value of up to 260 w/(m • K), 10 ~ 15 times of alumina ceramics) the relative dielectric constant, low (about 8.8) and reliable electrical insulation resistivity (> 1016 q, m – 1), high temperature resistance, corrosion resistance, non-toxic, good mechanical properties and thermal expansion coefficient of matching with the silicon (20 ℃ ~ 500 ℃, 4.6 x 10-6 K – 1) and a series of excellent properties, more and more widely applied in many fields of high technology, Which in many cases, requirements for AlN abnormity and micro parts, but the traditional mold and isostatic pressing process cannot be prepared ceramic parts of complex shape, plus the AlN ceramic material inherent low ductile and brittle and difficult to machining flaws, made using traditional machining method is difficult to preparation of the complex shapes of AlN ceramic parts. In order to give full play to the performance advantages of AlN, broaden its application range, and solve the problem of complex shape forming technology of AlN ceramics is one of the key links.
Excerpt from research and application development of aluminum nitride ceramics