Carbon-based chips: the future of the semiconductor industry

In the process of chip development, people began to explore new materials to replace silicon-based chips. Since carbon has many excellent properties, carbon nanotubes were used to make transistors, and the resulting carbon-based chips were made.

What is a carbon-based chip?

The concept of carbon-based chip may be unfamiliar to some people who do not know much about it. The carbon-based chip was introduced in the 1950s and 1960s. At that time, the development of integrated circuits had begun to speed up, so it had the resistors and capacitors needed for the circuit. These then became the core technology at that time. To integrate them on a small piece of silicon wafer by connecting wires, and then in the solder package inside the tube housing, this technology was a strong pillar of the whole development.

Later, in order to be able to improve the performance of the chip, people follow the law to enhance the number of transistors in a single chip. This law that every 18 months on the integrated circuit can accommodate the number of transistors doubled the performance also doubled. But then the related process difficulty also increased. Especially after entering the nanometer level, the physical limitations of the technology regarding material technology and systems led to a stagnation in the development of silicon-based chips. At this time, people also began to look for new materials to replace the silicon-based chips, of which carbon is the best choice because of its superior characteristics.

Silicon-based chips cannot be replaced in a short time

Using carbon nanotubes for conduction, the electron mobility of transistors can reach 1000 times that of silicon transistors. Moreover, the free of electrons in carbon nanotubes is very long, and the electron activity is freer, so it is less prone to frictional heating. In this way, the ultimate movement speed of transistor will be 5~10 times that of silicon transistor. The power consumption is only 1/10 of that of silicon transistors.

Although this concept has been mentioned, it is still not that simple to really replace the silicon-based chip. Because there is no way to measure the length of the current carbon economic tube, the carbon element is too active, and the dielectric constant is relatively low. So our current technology there are certain technical barriers, in addition to technical barriers, the cost and the cost rate of the problem, the same difficult to overcome at present.

Why the manufacturing of carbon-based semiconductors doesn't need photolithography?

It is certain that the processing of carbon-based integrated circuits will definitely not use photolithography! The essence of the traditional silicon-based chip manufacturing process is to produce hundreds of millions of transistors on silicon wafers through various processes in accordance with the requirements of the chip circuit design. And use the circuit to connect the transistors, so as to achieve the logic operation function of the chip.

The characteristics of silicon materials determine the production of silicon-based chips must go through a series of complex processes such as polishing, lithography, etching, and ion implantation to create transistors on wafers. The transistors of carbon-based semiconductors use carbon nanotubes, and the preparation process of carbon nanotubes is fundamentally different from the preparation method of silicon-based transistors, so the processing of carbon-based integrated circuits must not use photolithography.

The opening of the era of carbon-based semiconductors

At present, smart phones, computers, and other electronic devices have become an indispensable part of people's lives. Higher operating speed and longer power consumption have always been the goals we pursue. How to achieve these better performances is inseparable from the technological breakthroughs in the field of transistor research.

In order to break the bottleneck of physical constraints faced by the development of traditional silicon-based chips, scientists have started to research new materials to replace silicon-based chips in recent years. With its superior performance, carbon-based transistors have become a new generation of stars to improve the speed of computer operation and reduce the power consumption of electronic devices. However, for many years, it has been facing development problems in the manufacturing process and materials.

On September 25, 2020, Crommie, a professor of physics, Fischer, a professor of chemistry, and their colleagues at the University of California, Berkeley, and Lawrence Berkeley National Laboratory (Berkeley Lab) published a new study in Science, in which a team of chemists and physicists created a wire made entirely of carbon. metal wire.

The wire provides the last tool in the toolbox for making carbon-based circuits. The creation will certainly accelerate the research process for carbon-based transistors and provide a solid foundation for the manufacture of carbon-based computers.

Felix Fischer, a professor of chemistry at the University of California, Berkeley, said, "In the field of Carbon-Based Materials (CBM), the technology to integrate homogeneous materials is key." He noted that the ability to make all circuit components from the same material would make manufacturing easier, which has been one of the key factors missing in all-carbon-based integrated circuit architectures.

Conclusion

According to the International Technology Roadmap for Semiconductors (ITRS) committee, the performance of silicon-based semiconductors is predicted to reach its physical limits around the year 2020.

In 2020, the most advanced chip process node advances to 5nm. after 5nm, where does the global semiconductor industry go? Even if it is not 2020, the size limit of silicon-based transistors will eventually come, and then the chip industry should do?

In the face of the size limit of silicon-based materials, the switch to carbon-based materials is not a lost approach. The achievements of Peking University's research team in preparing carbon nanotube transistors are a step forward for the industrial application of carbon-based semiconductors.

On June 1, following the publication of the Science paper by the Peking University team, progress was also made in carbon nanotube research at the Massachusetts Institute of Technology. According to the paper published in Nature Electronics, MIT researchers have demonstrated that carbon nanotubes can be mass-produced in factories.

Since its discovery in 1991, carbon nanotube technology has been steadily advancing. Perhaps in the future, carbon-based materials will become a "major" presence in the semiconductor field, let us wait and see.