New breakthrough in semiconductor thick metal technology! One million times smaller than traditional casting, to achieve wafer-level complex metal structure casting
Recently, Maizhu Semiconductor, a startup company dedicated to the R&D and industrialization of wafer-level MEMS-Casting™ technology, successfully developed a miniature U-shaped electromagnet, an electromagnet target smaller than a fingertip It has become the smallest U-shaped electromagnet in the world at this stage. Compared with a straight spiral coil, a U-shaped coil can form a closed magnetic circuit, and the electromagnetic force generated as an electromagnet can be dozens of times larger than that of a straight electromagnet. However, the structure of a micro U-shaped coil is much more complicated than that of a straight coil, and it is difficult to achieve miniaturization by using traditional enameled wire winding methods. The MEMS-Casting technology can perfectly solve this problem and can be manufactured in batches.
What is the story behind this MEMS-Casting technology?
"Through 5000 years", from bronze to the industrial revolution, casting has a profound impact on human civilization
In June 2020, Elon Musk announced that the body of the Tesla Model Y will be manufactured in one piece using GigaCasting technology so that the 70 parts of the Model Y body will be combined into one. Not only can the production efficiency be greatly improved, but the consistency of the car body can also be greatly improved. GigaCasting, as its name suggests, is giant casting. This is the most recent highlight of casting technology in front of people.
In fact, casting technology has been profoundly affecting the development of human civilization. As early as 5000 BC, along with the development of pottery technology, bronze casting technology was invented. Prior to this, humans were basically in the Neolithic Age using ground stone tools, and the production efficiency was extremely low, and the emergence of bronze casting technology seemed to accelerate the development of human civilization.
The metal is melted, poured into a mold, and then cooled to form. The metal processing method of casting can not only achieve more complex structures, but more importantly, as a mass manufacturing method, it can greatly improve production efficiency. Because of its hardness and toughness, cast bronze is used to make production tools, such as plows for plowing, cutting knives, or bow arrows for hunting. Metal tools that can be manufactured in batches have greatly improved the ability of mankind to conquer nature. During the Warring States Period, China took the lead in developing iron casting technology. Cast iron has greatly improved hardness and toughness compared with bronze and is more suitable for the manufacture of production tools. It is no exaggeration to say that the development of cast iron technology has become one of the important factors for the rapid development of China's agricultural civilization.
It is precise because casting has made such an important contribution to the development of human civilization that some scholars once sighed: casting the most fundamental cornerstone of all civilizations unlocked the future of mankind and officially embarked on the path of conquering nature.
Time entered the 18th century. After the steam engine was improved from Watt in 1769, mankind began the journey of the industrial revolution, which produced a large amount of demand for machinery manufacturing. Casting technology, which can manufacture metal structures in large quantities, has begun to provide support for the industrial revolution. Casting not only met the production needs of a large number of industrial machine parts in the industrial revolution era but was also widely used to manufacture railroad tracks and promote the development of transportation.
Since the industrial revolution, the development of casting technology has never stopped. Die casting, centrifugal casting, vacuum casting, net body casting to extremely difficult single crystal casting, a new casting technology was invented. It is particularly worth mentioning here that single crystal casting, that is, the entire casting is a single crystal-like silicon wafer used for semiconductors. Single crystal casting is the only way to manufacture jet engine blades. The inside of the polycrystalline structure cannot withstand the high temperature and high pressure working environment of jet engines because of the weak inter-grain bonding force. To form a single crystal in casting, its solidification process must be extremely strictly controlled. Single crystal casting can be described as a peak in the development of casting technology.
"Semiconductor X casting =?" This doctoral team completed a "historical collision"
Nearly 200 years after the first industrial revolution, semiconductor technology has quietly risen, and mankind, therefore, ushered in the third industrial revolution based on information technology. There is no doubt about the far-reaching and extensive impact of integrated circuits based on semiconductor technology on human society. Decades after the rise of semiconductor technology, in the 1980s, a technology called microelectromechanical systems (MEMS) began to be derived from semiconductor technology. Unlike integrated circuits that manufacture logic computing devices on wafers, MEMS manufactures mechanical structures on wafers, such as cantilever beams, cavity films, or comb teeth, to achieve sensing and execution functions. If the integrated circuit is compared to the brain, then MEMS is more like facial features. After decades of development, MEMS devices have developed more maturely and have achieved large-scale commercial applications. For example, MEMS devices can be seen in portable or wearable devices such as smartphones and smartwatches. The automatic screen flip function of a smartphone is a classic application of MEMS devices. When we flip the phone, the MEMS gravity accelerometer in the phone senses the flip of the phone and automatically informs the system to complete the screen rotation.
Whether it is the steam engine of the first industrial revolution or the motor of the second industrial revolution, it needs to rely on cast mechanical parts. Casting is like an old man who works hard and has no complaints, and has been silently supporting the development of human civilization. As soon as semiconductor technology appeared on the stage of human history like a star, the exponential growth of Moore's Law made semiconductor technology unparalleled for the time being.
Casting and semiconductors, these two seemingly unmatched technologies, have finally ushered in a historic collision and opportunity. The MEMS-Casting technology developed by Maizhu Semiconductor is a perfect combination of this ancient metal processing technology and the emerging semiconductor technology.
MEMS casting technology is actually an unexpected research invention. In 2012, Dr. Gu Jiebin, the founder of Maizhu Semiconductor, returned to China from the UK where he had studied and worked for six years, and began to work at the Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences. Regarding the regret that the technology he did during his Ph.D. study at Imperial College London did not succeed in commercial transformation, Dr. Gu decided to study a new technical route to realize the micro-hole metallization filling problem via interconnection (TSV) in semiconductor advanced packaging. In the course of more than nine years of research, Dr. Gu and his team have overcome one problem after another. Finally explored and invented this micro-electromechanical casting technology. Fortunately, this research work was also strongly supported by Li Xinxin, then director of the State Key Laboratory of Sensing Technology.
Engineers are providing TSV filling services for customers with special micro-electro-mechanical casting equipment independently developed by Maizhu
MEMS itself is a multi-disciplinary ultra-precision machining technology. MEMS-Casting is based on the integration of fluid mechanics, thermodynamics, metal science, casting, mechanical engineering, electrical engineering, and semiconductor-related knowledge in physics. A multidisciplinary technology has been developed. In Dr. Gu’s own words, the solution to every problem has a story worth telling. For example, it is an interesting story to get the inspiration to solve the "cutting" problem of liquid alloy from a mercury thermometer. This technology-related research was accepted and published by Electron Device Letters (EDL), the most recognized electronic device journal in the academic industry. It was accepted as an oral report by the top international academic conference IEEE MEMS for two consecutive years and was the only one in the IEEE EDTM conference in 2021. First prize.
"The limit of miniaturization of casting" to realize the casting of complex metal structures at the wafer level
By applying a variety of micro-nano principles, MEMS casting technology can shrink the traditional casting by one million times. Therefore, for the first time, humans can realize the casting of complex metal structures on wafers. Before this, human beings had almost only one method of electroplating (casting) for the manufacture of metal structures with a scale of tens to hundreds of microns. However, electroplating has various shortcomings, such as complex process (needing a seed layer), the electrolyte used is toxic and easy to cause environmental pollution, and it is not suitable for manufacturing complex three-dimensional structures.
The MEMS casting technology perfectly solves these problems: because only vacuum and pressure are needed, there is no pollution problem; the molding efficiency is very high, generally, a wafer can be metalized by the casting process in only ten minutes; it is very easy to Realize the manufacture of complex three-dimensional structures, such as spiral coil structures. The spiral coil is a complex three-dimensional structure. If it is manufactured by electroplating, it needs at least three hours of electroplating. Using the micro-electromechanical casting technology, the entire coil structure can be metalized and formed in only ten minutes. In a sense, the MEMS casting technology has made up for the shortcomings of humans in the manufacture of metal structures of tens to hundreds of microns and is a breakthrough in semiconductor thick metal deposition technology.
Iterative R&D prototype diagram of special equipment for micro-electro-mechanical casting
Nowadays, as a low-level platform technology, MEMS casting can not only realize the micro-hole metallization filling of TSV but also can be used to manufacture complex three-dimensional structures on wafers, which caters to the current further miniaturization of semiconductor devices. The need for packaging. In order to better apply this technology and also respond to the national call for innovation and entrepreneurship, in 2018, Dr. Gu established Maizhu Semiconductor Technology Co., Ltd. to bring this technology on the journey of commercialization. At present, more than ten related intellectual property rights have been accumulated in this technical field. Many companies/institutions are cooperating with Maizhu Semiconductor to develop the application of this technology in lithography machines, fluxgate current sensors, and defense fields. . At the same time, this technology also presents huge application opportunities in fields such as consumer electronics.
The importance of metals to modern human civilization is beyond doubt. In order to make better use of metal, humans have never stopped seeking new metal processing methods. "The detector is in the shape of a perfect water drop, with a round head and a sharp tail. The surface is an extremely smooth total reflection mirror. The Milky Way is reflected in a smooth light pattern on its surface, making this drop of mercury look simple and beautiful." The water droplets in Liu Cixi's novel "Three-Body" are so pure and perfect, they are the ultimate yearning for metal. Every bit of human progress in metal processing will inevitably promote the advancement of civilization.
If Musk’s GigaCasting is the development of casting technology to a huge scale, Dr. Gu Jiebin’s MEMS-Casting is the other extreme of the development of casting technology, an extreme of miniaturization.