In the 5G era, can diamond/metal composites save overheated semiconductor devices?
With the rapid development of electronic technology, communication technology has gradually entered the 5G era. While the semiconductor materials are constantly being updated, integrated circuits are also moving in the direction of large-scale, high-integration, and high-power. The application of wide-bandgap semiconductor materials represented by SiC and GaN has led to the rapid development of insulated gate bipolar transistors (IGBTs), which is opening up a new situation for a new generation of information technology.
High power and high current density are the development trend of IGBT chips, which will inevitably cause overheating of electronic components. Research data shows that when the chip surface temperature reaches 70-80°C, the reliability of the chip decreases by 5% for every 1°C increase in temperature. More than 55% of the failure modes of electronic devices are caused by excessive temperature. To solve the heat dissipation problem, in addition to adopting more efficient cooling technology, it is urgent to develop new lightweight electronic packaging materials with a thermal conductivity greater than 400W/(m·K) and an expansion coefficient matching the semiconductor material. As a new type of electronic packaging material, diamond/metal composite materials have gradually moved to the center of the stage after more than ten years of research and development, and are highly expected.
Diamond has excellent performance such as large forbidden band width, high hardness and thermal conductivity, high electron saturation drift speed, high temperature resistance, corrosion resistance, and radiation resistance. It is used in high-voltage and high-efficiency power electronics, high-frequency and high-power microelectronics, deep Ultraviolet optoelectronics and other fields have extremely important application prospects. Diamond has the highest thermal conductivity (2200W/(m·K)) among the currently known natural substances, which is 4 times larger than silicon carbide (SiC), 13 times larger than silicon (Si), and larger than gallium arsenide (GaAs) It is 43 times larger, which is 4 to 5 times that of copper and silver. At present, diamond/metal heat-dissipating composite materials are promising.
Diamond is a cubic crystal, formed by covalent bonding of carbon atoms. Many of the extreme properties of diamond are the direct result of the sp³ covalent bond strength that forms a rigid structure and a small number of carbon atoms. Metal conducts heat through free electrons, and its high thermal conductivity is associated with high electrical conductivity. In contrast, heat conduction in diamond is only accomplished by lattice vibrations (ie, phonons). The extremely strong covalent bonds between diamond atoms make the rigid crystal lattice have a high vibration frequency, so its Debye characteristic temperature is as high as 2220K. Since most applications are much lower than the Debye temperature, the phonon scattering is small, so the heat conduction resistance with the phonon as the medium is extremely small. But any lattice defect will produce phonon scattering, thereby reducing thermal conductivity, which is an inherent characteristic of all crystal materials.
The thermal conductivity of diamond/copper composite materials is mainly limited by the design and preparation process of the composite material interface, specifically the intrinsic thermal conductivity of the copper matrix, diamond, the volume fraction of diamond, particle size, and the improvement of the interface between the two It is also particularly important. Generally, diamond with a complete crystal form, low nitrogen content, 100-500 um size is used as the reinforcing phase of the composite material to prevent the surface from transforming into a graphite-like phase, increase the volume fraction of diamond in the composite material, and help obtain high-quality diamond/ Copper composite material.
In the face of semiconductor components with ever-increasing power density, it is worth looking forward to whether diamond/metal composite materials can achieve rapid heat dissipation.
