Moore’s Law, which was born when the chaos of the Internet began, has gradually begun to fail in recent years. Since the chip process technology entered the 7nm era, the process dividend has gradually disappeared, and the cost of technology development has been continuously increased. This has hindered the development of some manufacturers, including Intel, in the process technology.
The gradual failure of Moore’s Law is because transistors are all on the same plane under the existing chip manufacturing technology, and their number cannot grow indefinitely. In theory, the extreme limit of the chip is about 2nm, and the current chip manufacturing process is already approaching this limit. Although manufacturers such as IBM are trying 3D chip packaging technology to continue Moore’s Law, there are still some technical problems in 3D stacking.
On the other hand, my country’s chip manufacturing industry currently lags behind the world in technology and is still far from the world’s advanced level. In particular, the manufacturing of advanced process technology chips is still blank in China, which makes the demand for chips in some high-precision fields in my country completely dependent on imports. According to statistics, my country’s domestic CPU market share in servers and computers in 2020 will only be less than 0.5%, and domestic chips have almost no presence in the high-performance computing market.
Today, although Chinese chip foundries represented by SMIC are catching up, they need new opportunities to cross the technological moat accumulated by developed countries in the chip field for decades. Carbon-based chip technology based on nano-carbon material transistors may be an opportunity for domestic chips to catch up in the future.
At a time when the chip industry as a whole is calling for change, there may be new possibilities for my country on this road.
The next-generation technology that replaces silicon-based carbon-based chips
At present, as the development of silicon-based chips is approaching the limit, major chip manufacturers are looking for new development directions of the chip industry in the future, and carbon-based chips are one of the shining stars.
Carbon-based chips are chips based on nano-carbon material transistors. Carbon-based chips have been considered by many scholars and well-known chip manufacturers at home and abroad as the next-generation technology that is most likely to replace silicon-based chips.
Due to the special geometry of graphene and carbon nanotubes, electron transport speeds in these materials greatly exceed current silicon-based materials. At the same time, there are no low-energy defects or dislocations in the metal that can cause atomic movement in the nanocarbon structure, so that the current intensity it can withstand is far higher than the current upper limit that the copper interconnects in the integrated circuit can withstand.
These properties make nanocarbon an ideal nanoscale conductive material.
The power consumption of transistors made of nanocarbon as a material is 5 times better than that of silicon transistors in a laboratory environment; the power consumption of carbon-based integrated circuits is 50 times better than the current technology.
In addition, the characteristics of low processing temperature and low operating power consumption of carbon nanomaterials make it easy for three-dimensional heterogeneous integration, which can overcome the technical problems faced by three-dimensional integrated circuits.In theory, 3D integrated circuits using nano-carbon materials have a comprehensive advantage of 1000 times the power consumption compared to silicon-based 3D integrated circuits.
For my country’s backward technology in the chip field, the manufacture of carbon-based chips also has the advantages of low cost and low threshold.
The material of the carbon-based chip determines that the 5nm process can be achieved by using a relatively simple planar device process in the field of chip manufacturing.In addition, the manufacturing of carbon-based chips can still use the current silicon-based chip manufacturing equipment, and when the equipment is three generations behind the current advanced process technology equipment, the chip performance can still be made comparable to the current advanced silicon-based chips, which makes my country’s chips It is possible for the manufacturing industry to break through the “stuck neck” on the new track.
To achieve mass production of carbon-based chips, high-quality carbon transistor fabrication technology is crucial. According to the planning of carbon nanotube integrated circuits by IBM Watson Research Center, the ideal carbon nanotube material should be a directional array of carbon nanotubes, and the optimal spacing is 5-10nm, that is, the carbon tube arrangement density is 100-200 pieces/ μm. In addition, the purity of carbon nanotube semiconductors must be greater than 99.9999%, which is also called the “six nines level”.
At present, there have been some researches on the preparation of high-semiconductor-purity carbon nanotubes at home and abroad. In 2013, IBM’s Cao and others produced carbon nanotubes with a semiconductor purity of 99%, but the density of carbon nanotubes prepared by this method will reach 500 pieces/μm, and the purity and density of carbon nanotubes do not meet the production requirements. need.
In 2016, Peng Lianmao’s research group at Peking University discovered a method of “evaporation-induced self-assembly” to align carbon nanotubes on the micrometer scale. Subsequently, in 2020, the research group prepared carbon nanotubes with a semiconductor concentration that conformed to the “six nine levels” and a density of 100-200 pieces/μm through the methods of “dimension-limited self-assembly” and “DNA-limited self-assembly”. , which indicates that the preparation process of carbon nanotubes in my country has reached the technical singularity required for carbon-based chips.
For the exploration of carbon-based integrated circuits, the world is still in its infancy.Since 2013, when Stanford University developed the first computer built entirely out of carbon nanotubes and able to successfully run simple programs, the field has never stopped. In 2020, the latest achievement of my country’s Peng Lianmao-Zhang Zhiyong team’s carbon-based integrated circuit speed reached 8.06GHz, which is at the world-class level.
In general, the development of silicon-based chips always has an end, and carbon-based chips currently seem to be the most likely successors of silicon-based chips in the future. At present, my country’s theoretical and practical accumulation on carbon-based chips is at the forefront of the world. Carbon-based chips may become the key for my country’s chip industry to break through the technological moat and go global.
Breaking the blockade of advanced lithography machines, the opportunity for domestic “core” corners to overtake
For this new track in the chip field, all walks of life in my country are paying great attention.
From a technical point of view, my country is currently not the most vulnerable in the field of chip design, but its manufacturing. TSMC and Samsung have the most advanced 5nm chip process technology, and the common point of their technology is the use of EUV lithography machine from ASML in the Netherlands.
Generally speaking, mainstream lithography technology is divided into DUV and EUV technology, the former means “deep ultraviolet” and the latter is “extremely deep ultraviolet”. DUV lithography machine can achieve 25nm process, Intel can achieve 10nm process technology with the dual-stage mode. However, the process technology below 10nm can only be achieved by EUV lithography machines at present. Due to the blockade of Western countries, Chinese chip manufacturing companies are currently unable to purchase EUV lithography machines for the preparation of advanced process technology chips.
However, the DUV lithography machine can fully meet the process requirements for the preparation of 5nm carbon-based chips. This indicates that in the future, perhaps we can develop advanced process chip manufacturing technology without relying on imported lithography machines. This actually gives my country’s chip industry an opportunity to overtake in a corner.
At the 2021 IMEC (European Microelectronics Research Centre) public meeting, participants proposed four ways to continue Moore’s Law and break the physical limits of 2-nanometer silicon-based chips. Among the four methods, the development scheme of carbon-based chips was unanimously approved by the expert group. Experts agree that carbon-based chips will be the next generation of mainstream chip technology after silicon-based chips.
Academician Peng Lianmao, the leader of carbon-based chips in my country, also revealed in an interview with People’s Daily Online that he believes that carbon-based chips are the best choice for the operation and development of smart cities. Academician Peng also predicted: “After fifteen years, carbon-based chips are expected to become the mainstream technology in the chip industry.”
At present, carbon-based chips are still in the initial stage of laboratory research, and the road to mass production is still “a long way to go”. According to preliminary estimates, in order to truly complete the leap from the laboratory to the office of carbon-based chips, it is necessary to ensure continuous capital investment for at least ten years, and the investment in carbon-based materials research requires billions of yuan. However, there is a lack of investor interest in the market due to the uncertain outlook for investment returns. In this case, government input and support are particularly important.
According to Xinhuanet, carbon-based materials will be included in the “14th Five-Year Plan” related development plan for the raw material industry.
In addition, according to Bloomberg, my country has a plan to develop carbon-based chips in 2021 to help Chinese chipmakers overcome U.S. sanctions. This shows the support for carbon-based chips in national policies and the expectations for their future.
In the foreseeable future, perhaps domestic chips can really lift the paddle called carbon-based chips and sail to the far side of the sea in the new era.
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