Micromachined or microelectromechanical systems or microsystems are microdevices or systems that can be mass-produced, integrate micromechanisms, microsensors, microactuators, and signal processing and control circuits, even peripheral interfaces, communication circuits, and power supplies. . Its main features are: small size (feature size range: 1Î¼m - 10mm), light weight, low energy consumption, stable performance; is conducive to mass production, reduce production costs; inertia, high resonant frequency, short response time; intensive High-tech achievements, high added value. The purpose of micro-mechanics is not only to reduce the size and volume, but also aims to develop a new technology field and form a mass industry through miniaturization, integration, search for new principles, new functional components and systems.
Micro-machining technology refers to microfabrication technology that is made into a mechanical device. The appearance and development of micro-fabrication is closely related to large-scale integrated circuits. Integrated circuits require more electronic components to be contained in a small-area semiconductor to form a circuit with complicated functions. The minimum line width in circuit fine patterns is a key technical indicator for improving the integration level of integrated circuits. Microfabrication is an advanced technology for microelectronics industry that manufactures micro-size components or thin-film patterns from micrometers to nanometers. Manufacturing Technology. Microfabrication technology is mainly based on the silicon planar processing and body processing technology developed from the microfabrication technology of semiconductor integrated circuits. After the mid-1980s, LIGA processing (micro-mold electroplating process), quasi-LIGA processing, ultra-fine processing Major advances have been made in micromachining processes such as micro-discharge machining (EDM), plasma beam machining, electron beam machining, rapid prototyping (RPM), and bonding technologies.
Micro-mechanical systems can accomplish tasks that large-scale electromechanical systems cannot accomplish. The close integration of micro-mechanics and electronic technologies will enable the availability of a wide range of micro-devices, which will be manufactured in high-volume integrated and low-cost, and will be widely used in many fields of human life. It can be expected that in this century, micro-machinery will gradually move from the laboratory to application, and will have a major impact on the development of industries such as industry, agriculture, information, environment, biomedicine, space, and national defense. Micro-mechanical processing technology is a very important and very active technology field in the field of micro-mechanics technology. Its development can not only promote the development of many related disciplines, but also is closely related to national science and technology development, economic and national defense construction. The development of micro-machining technology has huge industrial application prospects.
-- Foreign Development Status of Micro-machining Technology
In 1959, Richard P Feynman (Nobel Prize-winning physics in 1965) proposed the concept of micro-machinery. In 1962, the first micro-silicon pressure sensor was introduced, and the micro-mechanics of gears, gear pumps, pneumatic turbines, and couplings with dimensions of 50 to 500 Î¼m were developed. In 1965, Stanford University developed a silicon brain electrode probe, and later succeeded in scanning tunneling microscopes and micro sensors. In 1987, the University of California, Berkeley developed a silicon micro-electrostatic machine with a rotor diameter of 60 to 12 Î¼m, showing the potential of using a silicon micro-machining process to fabricate small movable structures and to be compatible with integrated circuits to create tiny systems.
Micro-machinery has been highly valued by government agencies, business circles, universities and research institutes abroad. MIT, Berkeley, Stanford, AT&T, and 15 scientists proposed a "statement of small machines, great opportunities: reports on emerging areas - microkinetics" in the late 1980s, claiming that "because of microkinetics The urgency of (microsystems) in the United States should go ahead in competition with other countries in such a new and important technology area." It is recommended that the central government's advance payment be 50 million US dollars for five years. Investing, and taking aerospace, information, and MEMS as the three major focuses of technological development. NASA invested $100 million in the development of the "Discovery Microsatellite". The National Science Foundation has developed MEMS as a newly emerging research area to fund the research of microelectronic mechanical systems. It has been funding MIT since 1998. Eight universities such as the University of California and Bell Laboratories are engaged in research and development in this area. The annual funding has been increased from 1 million to 2 million to US$5 million in 1993. The "US Department of Defense Technology Plan" report released in 1994 listed MEMS as a key technology project. The U.S. Department of Defenseâ€™s Advanced Research Projects Agency actively leads and supports MEMS research and military applications. A MEMS standard process line has now been established to promote the research and development of new types of components/devices. U.S. industry is focused on the research of sensors, displacement sensors, strain gauges, and accelerometers. Many institutions have participated in the research of micro-mechanical systems, such as Cornell University, Stanford University, University of California, Berkeley, University of Michigan, University of Wisconsin, and Old Reynoldsmore National Research. The Berkeley Sensors and Actuators Center (BSAC) of the University of California has received funding of 15 million yuan from the Department of Defense and more than a dozen companies, and established a 1115m2 ultra-clean laboratory for research and development of MEMS.
In 1997, Japanâ€™s Ministry of International Trade and Industry began a 10-year, 25-billion-yen micro-scale large-scale research project to develop two prototypes, one for medical treatment, diagnosis and microsurgery into the human body, and the other for industrial use. , Maintenance of micro cracks in aircraft engines and atomic energy equipment. The plan includes dozens of companies including Tsukuba University, Tokyo Institute of Technology, Tohoku University, Waseda University, and the Fujitsu Institute.
European industrialized countries have also successively invested in the research and development of microsystems. Germany has started a microprocessing 10-year plan project since 1988. Its Ministry of Science and Technology allocated 40,000 mark in 1990-1993 to support the study of the â€œMicrosystems Programâ€ and The microsystems have been listed as the focus of the development of science and technology at the beginning of this century. The LIGA process pioneered by Germany has provided new technological means for the development of MEMS and has become the preferred process for the production of three-dimensional structures. France's 70 million francs "Microsystems and Technology" project launched in 1993. The European Community formed the "Multifunctional Microsystems Research Network NEXUS" and coordinated the research of 46 institutes. Switzerland also invested in MEMS development on the basis of its traditional watch manufacturing industry and small precision machinery industry. In 1992, it invested 10 million US dollars. The British government has also formulated a nanoscience program. Eight projects have been listed for research and development in the fields of mechanics, optics and electronics. In order to strengthen the development of MEMS in Europe, some European companies have formed MEMS development group.
A large number of micro-mechanics or micro-systems have been studied. For example, a miniature tweezers with a tip diameter of 5 Î¼m can pick up a red blood cell, and a micro-pump with a size of 7 mmÃ—7 mmÃ—2 mm can reach a car that can start up at 250 Î¼l/min. The machine butterfly that flies in the magnetic field, as well as the miniature inertial assembly (MIMU) that integrates the micro-velocity meter, the miniature gyro and the signal processing system. Germany created the LIGA process and made cantilever beams, actuators, and micro-pumps, micro-nozzles, humidity, flow sensors, and a variety of optics. Caltech in the United States adhered a considerable amount of 1mm microbeams to the wing surface of aircraft to control its bending angle to influence the aerodynamics of the aircraft. The mass-produced silicon accelerometer in the United States integrates microsensors (mechanical parts) and integrated circuits (electrical signal sources, amplifiers, signal processing, positive detection circuits, etc.) on a silicon chip in a 3 mmÃ—3 mm range. Japan's small-scale centimeters of micro-lathe can be used to machine micro axes with an accuracy of 1.5 Î¼m.
-- Domestic status of micro-machining technology
China's Ministry of Science and Technology, the National Natural Science Foundation, the Ministry of Education, and the General Armament Department have been tracking foreign micro-machinery research and actively conducting MEMS research. Existing microelectronic devices and synchrotrons provide the basic conditions for microsystems. The development of microdrives and micro-robots has long been listed in the National 863 High-Tech Plan and Climbing Plan B. Nearly 40 research groups have achieved the following research results. Guangdong University of Technology cooperated with the University of Tsukuba, Japan, to conduct research on biological and medical micro-robots. It has developed one-dimensional and two-dimensional linked piezoelectric ceramic actuators with a displacement range of 10 Î¼mÃ—10 Î¼m; a displacement resolution of 0.01 Î¼m, with an accuracy of At 0.1 Î¼m, a 6-DOF miniature robot is being developed; Changchun Institute of Optics and Precision Mechanics has developed a piezo motor with a diameter of Î¦3 mm, an electromagnetic motor, a micro-testing instrument, and a micro-operating system. Shanghai Metallurgical Research Institute has developed micro-motors, poly-silicon beam structures, micro-pumps and valves. Shanghai Jiaotong University developed a Î¦2mm electromagnetic motor, and Nankai University carried out research on micro-robot control technology.
Many institutions in China have carried out corresponding research on a variety of micro-machining methods, and have laid a certain processing foundation, can carry out silicon plane processing and bulk silicon processing, LIGA processing, micro-EDM processing and stereolithography modeling processing Wait.
-- The development trend of micro-machining technology
The development of micro-machining technology has just gone through more than 10 years. While the processing technology has been continuously developed, a number of micro-devices and systems have been developed, showing great vitality. As a mass-produced micro-mechanical product, it will win the market with its low price and excellent performance in bio-engineering, chemistry, micro-analysis, optics, defense, aerospace, industrial control, medical, communications and information processing, agriculture and home services, etc. The field has a potentially huge application prospect. Currently, large-scale production of micro-mechanical products such as miniature pressure sensors, micro-accelerometers and inkjet print heads has captured a huge market. At present, the market is dominated by fluid-conditioning and control MEMS, followed by pressure sensors and inertial sensors. In 1995, the sales volume of global micro-machinery was US$1.5 billion. It is expected that by 2002, the value of related products will reach US$40 billion. Obviously, micro-machines and their processing technologies have huge market and economic benefits.
Micro-machinery is a cross-cutting science, and the development of each technology associated with it will promote the development of micro-machinery. With the continuous development of microelectronics, materials science, and information science, micro-machinery has a better foundation for development. Due to its huge application prospects and economic benefits, as well as the attention of governments and enterprises, the development of micro-machinery will surely have a greater leap forward. New principles, new functions, new structures, micro-sensors, micro-actuators and systems will continue to emerge, and large mechanical devices can be embedded to increase automation and intelligence.
As the most critical technology of micro-machinery, micro-machining technology is bound to have a big development. Silicon processing, LIGA processing, and quasi-LIGA processing are moving toward more complex, higher-depth microstructures that adapt to a variety of demanding material and surface properties, as well as the development of different materials, especially functional material microstructures that are easier to integrate with circuits. The combination of various processing technologies is also an important direction. Micro-machinery is in the design direction of the development of the design system to achieve the analysis and evaluation of the characteristics of devices and systems while the structure and process design, and the introduction of virtual reality technology.
The priority areas for the development of micro-processing technology in China are biology, environmental monitoring, aerospace, industry and national defense, etc. Several micro-machinery research and development bases with advanced world standards have been established, and new physical phenomena on the micro-scale have also been emphasized. The research of new and effective effects has accelerated the research and development of micro-mechanics in China and has met the challenges of the 21st century technology and industrial revolution.
- Key technologies for micro machining
Micro-machinery is a new, multi-disciplinary, high-tech area that faces many topics and involves many key technologies.
When a system's feature size reaches the micro- and nano-scale, many new scientific problems will arise. For example, as the size decreases, the ratio of surface area to volume increases, surface mechanics and surface physics will play a leading role, and traditional design and analysis methods will no longer be applicable. Problems such as tribology and micro-heating will be crucial in the micro-system. The research on the scale effect of micro-systems will contribute to the innovation of micro-systems.
Micromachinery is not a direct miniaturization of traditional machinery, it goes far beyond the concept and category of traditional machinery. Micromachinery is completely different from traditional machinery in terms of scale effects, structure, materials, manufacturing methods, and working principles. The research on the scale effect, physical properties, design, manufacture, and testing of micro-systems is an important research area in the field of micro-systems.
In the microsystems research work, some domestic and foreign research institutions have been miniaturizing the size effect, microfabrication technology, micro-mechanical materials and micro-structures, micro-sensors, micro-actuators, micro-mechanics measurement technology, microfluidic control and micro System integration control and applications have achieved phased results in varying degrees. Micro-machining technology is a key basic technology for the development of micro-mechanics, including micro-mechanical design micro-fabrication technology, micro-mechanical assembly and packaging technology, system characterization and measurement technology, and micro-system integration technology.
Key technologies in the field of micro-machining technology are:
1, micro system design technology
Mainly in the micro-structure design database, finite element and boundary analysis, CAD/CAM simulation and simulation technology, micro-system modeling, micro-miniaturization of the size and micro-scale theoretical research is also an indispensable topic of design research, such as: Force size effects, micro-structure surface effects, microscopic friction mechanisms, heat conduction, error effects, and micro-component material properties.
2, micro-processing technology
Mainly refers to the high-depth than the multi-layer microstructure of the silicon surface processing and body processing technology, the use of X-ray lithography, electroforming LIGA and the use of ultraviolet quasi-LIGA processing technology; micro-structure of special precision machining technology, including micro-sparking, energy beam Processing, three-dimensional photolithography forming processing; special materials, especially functional materials, micro-structure processing technology; a combination of multiple processing methods; micro-system integration technology;
3, micro-machine assembly and packaging technology
Mainly refers to the adhesion of the bonding material, electrostatic sealing of silicon glass, silicon silicon bonding technology and self-aligned assembly technology, with the three-dimensional moving parts packaging technology, vacuum packaging technology and other new packaging technology exploration.
4, Microsystem Characterization and Testing Technology
There are structural material property testing techniques, micro-mechanics, electrical and other physical measurement techniques, micro-device and micro-system performance characterization and testing techniques, micro-system dynamics testing techniques, and micro-device and micro-system reliability measurement and evaluation techniques.