In the vast universe, a metallic-metal-alloy cosmic probe passes at superluminal speed. It is composed of protons and neutrons that are locked by strong mutual forces. Because the surface is absolutely smooth, it can reflect all electromagnetic waves and is invincible.... 3. Liu Cixin mentioned a spacecraft named 'Water Drops' in the science fiction "Three Body."
In fact, the pursuit of 'absolute smoothness' by humans has also been transformed from a scientific fantasy to a practical one, such as the ultra-precision polishing technology that promotes the revolution of integrated circuits. As described in the “Three-body,” the current most advanced chemistry Chemical mechanical polishing (CMP) technology has also entered the atomic scale. When the electronics industry powerhouses compete to climb or reach the peak of this process, we can only look up.
Modern electronics industry, ultra-precision polishing is the soul
Physical polishing is the most commonly used polishing technique before the 1980s, but the rapid development of the electronics industry places increasingly stringent requirements on the size and flatness of the material devices. When a substrate with a thickness of one millimeter needs to be made into dozens of In the case of integrated circuits of million layers, traditional old polishing techniques are far from the requirements.
China's Ultra-precision Polishing Process Blocked by U.S. and Japan
Take wafer fabrication as an example. Polishing is the final step of the entire process. The purpose is to improve the micro-defects left by the wafer prior to wafer processing to achieve the best parallelism. ' Dr. Wang Qi, National Institute of Nanosciences, Chinese Academy of Sciences Science and Technology Daily reporter introduced.
Today's optoelectronic information industry level, the sapphire, single crystal silicon and other materials used as optoelectronic substrate materials are more and more precise and have reached the nanometer level. This means that the polishing process has also entered the nanoscale. The degree of ultra-precision.
The importance of ultra-precision polishing technology in modern manufacturing, its application areas can directly explain the problem: integrated circuit manufacturing, medical equipment, auto parts, digital accessories, precision molds, aerospace.
Wang Qi said: 'The mission of ultra-precision polishing technology in the modern electronics industry is not only to planarize different materials, but also to planarize multi-layer materials, so that a few millimeters of square silicon through this 'global flatness The formation of mega-transistors consisting of tens of thousands to millions of transistors. For example, human computers were transformed from dozens of tons to a few hundred grams now. No super-precision polishing is possible. It is a technological soul.
The core technology is frozen, and domestic demand is controlled by people
Zhejiang Jingsheng Electromechanical Co., Ltd. is one of the pioneers in the pursuit of 'global flatness' in China's electronics manufacturing industry. Sun Ming, the company's technical director for polishing process research and development for many years, told reporters: 'If we compare the polishing process to making pancakes, we can The neck is the pot, others' pots are non-stick, and we can't do it.'
Sun Ming said that the 'pot' is the core device of the polishing machine - 'grinding disc'. Ultra-precision polishing on the polishing machine grinding disc material composition and technical requirements are almost harsh, this special steel plate synthesis, not only to meet Nano-precision precision automation, but also have accurate thermal expansion coefficient.
When the polishing machine is in high-speed operation, if the thermal expansion results in thermal deformation of the grinding plate, the flatness and parallelism of the substrate cannot be guaranteed. However, the thermal deformation error that cannot be allowed to occur is not several millimeters or several micrometers. It is a few nanometers.
At present, the world's top polishing processes such as the United States and Japan can already meet the precision polishing requirements for 60-inch substrate materials (which are oversized). They control the core technology of ultra-precision polishing processes and firmly grasp the initiative of the global market. In fact, by grasping this technology, it has largely controlled the development of electronic manufacturing.
According to Sun Ming, the grinding discs of Japanese-made polishing machines are custom-made, and they are not subject to mass production, which directly limits the imitation of other countries. Wang Qi also told reporters that the United States' polishing equipment is sold to China, and the prices are generally more than 10 million yuan. Sales orders have been placed until the end of 2019. No orders were accepted before.
“In the face of such a tight technical blockade, we are in a hurry. During the Spring and Autumn Period, Luban invented stone for humans and helped agricultural civilization. Nowadays, our progress in the electronics industry is once again stuck on the neck by a grinding wheel. But again, now we Have to wait, either to import, or independent research and development. 'Wang Qi said.
Peaking technology, asking for help
In fact, in the field of ultra-precision polishing, China is not without its achievements. As a set of highly technical synthetic processes, ultra-precision chemical mechanical polishing process must be composed of equipment and materials (polishing liquid), both of which are indispensable.
In 2011, the “Cesium Dioxide Microsphere Size Standard Reference Material and Its Preparation Technology” developed by Dr. Wang Qi received the first prize for technical invention from the China Petroleum and Chemical Industry Federation. The related nanometer granularity standard substance obtained the national measurement instrument license and the state The first-class standard material certificate. The super-precision polishing production test effect of new ceria material surpassed the traditional foreign materials in one fell swoop and filled the gap in the field.
However, Wang Qi said: 'This does not mean that we have climbed to the top of this field. For the entire process, only the polishing fluid and no super-precision polishing machine, we can only sell materials at most.'
Sun Ming believes that the specific requirements of the modern electronics manufacturing industry can be clearly defined to overcome the direction of ultra-precision polishing process: 'The polishing process needs to meet the current requirements of the electronics industry, can be summarized as ultra-precision, large size. With top-level The polishing material is only the basis. Based on this, we also need to go in two steps, first to solve the disc problem, and then to solve the problem of polishing area expansion.
According to Sun Ming, the material composition and production process of polishing discs in the United States and Japan has always been a mystery. In other words, buying and using their products does not mean that they can copy or even copy their products. This is two different things.
'What kind of materials and processes can be used to synthesize such a low thermal expansion rate, high wear resistance, and ultra-precision grinding discs on the grinding surface is the technical problem that we must concentrate on first, and once this problem is solved, the 60-inch polishing surface will not Then is the dream. And such a core technology can never be expected to be obtained from others. We have no choice but to rely on ourselves. ' Sun Ming said.