With the explosive development of new technologies such as new energy, 5G and artificial intelligence, the global demand for chips based on high-quality semiconductor materials has increased. In recent years, the United States has tried to retain China in the field of semiconductor chips, which has led to an unprecedented increase in the Chinese people's attention to the semiconductor industry. Recently, Huawei and Harbin Institute of Technology jointly applied for a patent for a hybrid bonding method for three-dimensional integrated chips based on silicon and diamond, which has attracted widespread attention in the technological community. In fact, in the field of next-generation semiconductor materials, countries are also making efforts.

What are the advantages of diamond semiconductors

According to patent materials, the invention patent jointly applied by Huawei and Harbin Institute of Technology has achieved three-dimensional heterogeneous silicon/diamond integration based on the Cu / SiO2 hybrid bond. External analysis suggests that the advancement of this technology lies in the successful combination of silicon and diamond, two materials with very different properties, opening up new ideas in the field of chip manufacturing. With the continuous development of emerging technologies, the requirements for chip performance are becoming higher and higher. While traditional silicon-based chips meet these needs to some extent, they still have certain limitations in certain specific fields, such as high-power, high-temperature environments. Diamond, as a material with excellent thermal, electrical and mechanical properties, is considered one of the ideal choices for the next generation of chips.

Semiconductor devices manufactured in diamond thin films

Japan also has high hopes for diamond semiconductors. According to Nihon Keizai Shimbun's website, Japanese start-up OOKUMA plans to put the diamond semiconductor, known as the "final semiconductor," into practical use, which will be put into production as early as 2026. According to reports, research by Saga University in Japan has shown that diamond semiconductors can operate at temperatures 5 times higher and voltages 33 times higher compared to conventional silicon-based semiconductors. The performance is also superior to common third-generation semiconductors such as silicon carbide and gallium nitride. This feature makes it expected to be used in fields such as pure electric vehicles, high speed communication and satellite communication in high voltage environments.

It is reported that diamond semiconductor devices produced by the OOKUMA company will be used for the first time for the treatment of nuclear waste at the Fukushima Daiichi Nuclear Power Plant. Only robots that can withstand extremely high radiation intensity are able to inspect and clean up melted fuel left behind after the core melts at the Fukushima Daiichi Nuclear Power Plant. But ordinary semiconductor devices have a very short lifespan in extreme environments, while OOKUMA found that diamond semiconductor devices can still function normally in aggressive environments with high temperatures of 450 degrees Celsius and extremely high radiation intensity. In addition, to protect semiconductor devices from strong radiation and high temperature environments, it was originally necessary to engage the robot's core with heavy lead and equip it with specialized cooling devices. However, with diamond semiconductors, these devices can be eliminated, thereby reducing the robot's weight and improving work efficiency. OOKUMA plans to mass-produce diamond semiconductors treating waste from nuclear power plants. In order to strive for application in satellite communication, the company has begun joint research with Mitsubishi Electric and others. We will also promote the development of components for pure electric vehicles with Japanese manufacturers within the year.

The rapid development of third-generation semiconductor materials

Diamond semiconductors are one of the third generation semiconductor materials that are currently receiving a lot of attention. Li Yingrui, a postdoctoral fellow at the Shenzhen Research Institute of Northwest Polytechnic University, told Global Times reporters that semiconductors are a series of materials with conductivity properties between conductors and insulators at room temperature. Common semiconductor materials include silicon, germanium, gallium arsenite and so on. The conductivity of semiconductors is controllable and can be adjusted by adding impurities (doping) or by changing the temperature. Using the characteristics of semiconductor materials, it is possible to produce semiconductor devices-transistors-that control the voltage or current of another port through the voltage or current of a port. Connecting transistors with components of resistors, capacitors and other passive devices forms an integrated circuit. The essence of the chips is to create integrated circuits in semiconductor substrates (also known as wafers) that can achieve a number of specific functions.

It is reported that the first generation of semiconductor materials refers to semiconductor materials of elements represented by silicon and germanium, which are widely used. Currently, more than 90% of semiconductor products are made of silicon-based materials; second-generation semiconductor materials are composite materials represented by gallium arsenite and indium phosphide. Li Yingrui believes that from the perspective of materials, the future direction of development will inevitably be broad bandgap semiconductors. Bandgap width is an important characteristic parameter of semiconductors, and its size is mainly determined by the semiconductor band structure, which is related to the crystal structure and atomic bond properties. Bandgap width determines the conductivity of semiconductors at different temperatures and electric fields. Wide bandgap semiconductors can operate at higher temperatures, voltages and frequencies, thus reducing losses and improving efficiency. This advantage is particularly important for new energy vehicles, 5G communication, aerospace and military systems, and can also be applied to more complex environments. Bandgap broad semiconductors are generally referred to as third generation semiconductors, mainly including silicon carbide, gallium nitride, zinc oxide, diamond, aluminum nitride, etc. They have the advantages of large bandgap width (> 2,2 ev), high breakdown electric field, high thermal conductivity, Strong radiation resistance, high luminous efficiency and high frequency. They can be used for high temperature, high frequency, radiation resistance and high power devices, and are also a new type of semiconductor device vigorously developed by various countries.

Gallium nitride wafer

For example, silicon carbide semiconductor devices, which have begun to be widely used, have good heat resistance, stress resistance and extremely low conduction energy loss compared to first and second generation semiconductor materials, Making them ideal materials for the manufacture of high voltage power devices and high power RF devices. And other widely used material of gallium nitride can significantly improve the performance and design of semiconductors. Compared to other materials, it can withstand higher gains at higher frequencies with greater efficiency. Gallium nitride has excellent thermal performance and higher breakdown voltage, making it possible to design and manufacture semiconductor materials that are smaller and thinner without affecting power consumption, reliability or safety. In the age of the Internet of Things 5G, where everything is interconnected, this is an undeniable advantage.

Emerging materials are gaining more and more attention

In addition to third-generation semiconductor materials, there are also more emerging materials that are receiving increasing attention. The 2023 Nobel Prize in Chemistry was awarded to three scientists for the discovery and synthesis of quantum dots. So-called quantum dots are a type of small or nanocrystal particles, which are semiconductor materials with a diameter of between 2-10 nanometers. They are semiconductor nanostructures that are linked by conduction band electrons, valence band bores, and excitons in three spatial dimensions. In addition to its applications in the fields of display and lighting, the Nobel Committee on Chemistry stated that quantum dots have the potential to make contributions in fields such as quantum computing, flexible electronic products, micro sensors, and thinner solar cells in the future.

In addition, the application of two-dimensional materials such as graphene in the field of semiconductors has also been widely studied. Graphene is a two-dimensional material composed of a single layer of carbon atoms, which has excellent electronic mobility and thermal conductivity. The unique properties of this material provide new possibilities for future electronic devices such as ultra-fast transmission devices and highly integrated sensors.

The next generation of chips requires innovative development in semiconductor materials.

In addition to materials, technological advances in other areas are also expected to further promote the progress of semiconductor technology. Li Yingrui's research team recently launched a new generation of semiconductor photon count infant imaging system, breaking the technological lock of foreign countries. This mainly depends on the team's advances in the three key technologies affecting photon counting applications, including crystal materials, ASIC specific reading chips and multi spectral imaging algorithms, which have reached the international advanced level in the field of crystal solutions.

Faced with challenges such as the slowdown in the growth rate of Moore's Law, academic Dai Qionghai's team from the Department of Automation at Tsinghua University recently proposed a new computing architecture to break free of Moore's Law: analog optoelectronic chips. In visual tasks, its computing power has reached more than 3000 times that of today's high-performance commercial chips. The research team introduced in an interview with Global Times reporters that the new computing structure starts from the most fundamental physical principles, combines optical computing based on the spatial propagation of electromagnetic waves with pure analog electronic computing based on Kirchhoff's law, "breaks free" From the physical bottleneck of data conversion speed, precision and power consumption in traditional chip architectures, and it breaks the three challenges of integrating large-scale computing units, efficient non-linearity and high-speed, single-chip optoelectronic interface.