Research history and development trend of CVD diamond film in China

I. Historical review

At the beginning of 1987, China's "863 Program" was officially launched. Prof. Chen Nanxian, then the leader of the functional materials expert group in the new material field of the “863 Program”, published information on diamond film research based on the US Star Wars program, and dozens of publicly available materials on diamond films brought back from the United States. Most of them are diamond-like carbon films (DLC). It is strongly recommended to include the diamond film as a topic in the first batch of functional materials expert group startup projects. At the time, including Professor Chen himself, all members of the expert group had not seen the diamond film, and the knowledge of the preparation and characterization of the diamond film was almost zero. Among the four units approved by Jilin University, Sichuan University, Beijing Institute of Technology, and Beijing Institute of Artificial Crystals, which were approved for the first batch of diamond film research, only Professor Jin Zengsun of Jilin University actually conducted CVD diamond film during their study in Japan. Research. The initial research objectives set by the expert group are very simple. Regardless of the method used, diamond film samples must be prepared within one year, submitted to Beijing University of Science and Technology for testing and evaluation, and based on the results of the assessment, whether to continue funding.

( 1) Standards for assessment

1. Scanning electron microscopy shows the facet features of diamond grains;

2. The diamond characteristic peak at the attachment of 1332 cm ^-1 can be seen on the Raman spectrum;

3. X-ray diffraction spectrum shows the diffraction peak of diamond.

The research team of Jilin University produced the first diamond film in China in early 1987, obtained the characteristic Raman peak of diamond, and published a paper. In November 1988, a total of nine units provided samples of the diamond film they prepared. The test results of all samples were published at the Beijing University of Science and Technology. In order to ensure the openness and fairness of the “863 Plan”, units that have not entered the “863 Plan” may also request samples for testing. Unexpectedly, the diamond film prepared by the hot wire CVD method provided by Hunan University (the head of the project for Professor Chen Benjing) who did not enter the "863 Program" has the highest quality, which is better than all the units inspected. In accordance with the principle of fairness and fairness of the "863 Program," Hunan University has thus successfully entered the "863 Program."

In less than three years, the 863 “Eighth Five-Year Plan” started in 1991, and the research unit that entered the diamond film subject by expert review quickly expanded to 13 companies. Diamond film preparation technology also covers four major technologies, namely hot filament CVD, microwave plasma CVD, DC Arc Plasma Jet CVD, and Combustion deposition. In accordance with the National Science and Technology Commission's emphasis on catching up and applying the "863 Program", diamond film tool applications, thermal applications, electronics applications, diamond film sensors, and diamond film homogenous and heteroepitaxial, diamond film p-type blending Miscellaneous, as well as low-temperature deposition of diamond films and optical coatings, etc., have become the targets of research at the time.

( II) Major events occurred during the “Eighth Five-Year Plan” period (1991-1995 )

1. Jilin University began research on hot cathode CVD while continuing the growth of hot-wire CVD diamond film. This technology later flowed into South Korea and was further developed in Korea, eventually becoming one of the preparation techniques for large-area high-quality diamond self-supporting membranes;

2. Professor Hou Li from the Institute of Artificial Crystals successfully brought the EACVD technology (Electronic Enhanced Hot Filament CVD) from Penn State University back to China, and successfully produced a large-area (2 inch) tool-grade diamond self-supporting film (with substrate). Separated diamond thick film). This research advancement has made it possible to use diamond film tools (diamond wire drawing cores, diamond film brazing cutting tools, and other friction and wear applications) to begin to demonstrate the industrial application prospects of diamond films;

3. Beijing University of Science and Technology continued to conduct microwave plasma CVD diamond film cryogenic deposition and optical coating research. Since 1991, it has cooperated with the Hebei Academy of Sciences to switch to DC Arc Plasma Jet CVD equipment and process research. . In 1993, a 10 kW DC Arc Plasma Jet CVD diamond film deposition device was successfully developed with a maximum deposition rate of 150 μm/h and a maximum deposition area of ​​Φ50 mm. Exceeding the DC Arc Plasma Jet CVD device of Beijing Institute of Technology: deposition speed and maximum area, showing good scalability and industrial application prospects. At the beginning of 1994, the State Science and Technology Commission decided to set up a major key technology project of the "863 Program" to accelerate the industrial application process of the "863 Program" project. “Research on key technologies for diamond film preparation and application” entered smoothly. Jilin University (applications of thermals and electronics), Beijing Institute of Artificial Crystals (tool application) and Beijing University of Science and Technology (key equipment for large-area diamond film preparation) jointly undertake the research tasks of this major key technology project. In order to catch up with the launch of the "Ninth Five-Year Plan", this major key technology project must be completed by the end of 1995 (about one and a half years). In February 1996, the project was accepted by the National Science and Technology Commission at the Beijing University of Science and Technology. The expert group consisted of seven senior academicians including Shi Changxu, Lin Lanying, Ke Jun and Xiao Jimei. The experts gave high marks to the results achieved by the project team. The news broadcast of CCTV at 7:00 pm has also been reported.

( 3) Main results

1. Jilin University: Further progress was made in EACVD and hot cathode CVD. The first application of diamond film as a heat sink on a semiconductor laser was demonstrated, and a laser diode heat sink prototype device was demonstrated.

2, Artificial Crystal Research Institute: EACVD method, showing 2 inch tool-grade diamond self-supporting film and diamond film drawing core, diamond film brazing tools and other diamond self-supporting film product samples;

3. Beijing University of Science and Technology (cooperating with Hebei Academy of Sciences): Completed the development of a 100 kW DC Arc Plasma Jet CVD diamond film deposition system (using a magnetron long-channel rotary arc plasma torch technology with Chinese characteristics and independent intellectual property rights) A 110 mm uniform diamond film sample (thickness of about 100 μm) was demonstrated with a deposition rate of 30-40 μm/h. At the 10th Anniversary of the 863 Program held in 1996, photographs of the above-mentioned 100 kW DC Arc Plasma Jet CVD system were placed at the entrance to the "863" new material field.

During the "Ninth Five-Year Plan" period (1996-2000), it was the most prosperous period for domestic CVD diamond film research. The research unit has rapidly developed to more than 30. The “863 Ninth Five-Year Plan” has 17 participating units, and does not include three participating in the “Ninth Five-Year Plan” (Jilin University, Institute of Artificial Crystal and Beijing University of Science and Technology). The research content is basically synchronized with foreign research content, electronics, optics, thermals, mechanics (tools and friction and wear), doping and extension, sensors, and everything. In addition to the "863 Program", the Natural Science Foundation also gave active support.

( iv ) Major events during the “Ninth Five-Year Plan” period (1996-2000 )

In 1996, the “Ninth Five-Year Plan” major project (diamond film and its application) was launched, among which: Jilin University was responsible for the thermal and electronic applications of diamond films, the Institute of Artificial Crystals was responsible for tool applications, and Beijing University of Science and Technology was responsible for optical applications. It also puts forward the industrialization target for the application of tools, and requires an annual output value of 10 million yuan.

1. Professor Lin Zhangda of the Institute of Physics of the Chinese Academy of Sciences proposed “hetero-epitaxial diffusion of diamond film on silicon” to obtain funding for major fund projects, and at the same time obtain financial support from a certain enterprise in Hong Kong;

2. The Institute of Artificial Crystal and Nanjing Tiandi Group Co., Ltd. established Beijing Dongfang Tiandi Diamond Co., Ltd., which is the first CVD diamond film enterprise in China;

3. Beijing University of Science and Technology produced a 30mm optical grade transparent diamond film by DC Arc Plasma Jet CVD at the end of 1997. It is listed as one of the major technological advances in the new material field of the "863 Program" in 1997. However, due to the failure to complete the plan for the output value of the artificial crystal of 10 million yuan, the acceptance of the "Ninth Five-Year Plan" major project of the "863" plan did not receive the same high evaluation as the "eight-five" major key technology projects. Individual review experts have questioned the application and industrialization of CVD diamond films. Professor Li Kejian, who was then the main leader of the Fund Committee, expressed at the acceptance meeting that “from the “seventh five-year plan” to the “ninth five-year plan”, you have already engaged in three five-year plans. If a “high-tech enterprise” has a production value of 10 million yuan, Can't get it, can it be considered high technology?" Strict accusation.

Professor Li Kejian's questioning is not the opinion of individual people. Many people from the State Science and Technology Commission and the fund committee and other departments in China have similar views. In foreign countries, the situation is similar to that in China. The CVD diamond film research also entered a low tide (half times earlier than domestic). CVD diamond film research has been applied from the beginning, and people's expectations for CVD diamond film are too high. Therefore, when several important applications of diamond film are blocked, the most typical one is diamond high temperature semiconductor. Many people have cheered diamonds. The advent of the times, but when large-area diamond heteroepitaxial has not been realized, and the n-type doping of diamond films is also difficult, the disappointment quickly spread. Therefore, in the "10th Five-Year Plan" from 2001 to 2005, CVD diamond film research finally experienced the "coldest winter." The "863 Program" finally no longer lists the diamond film topics. Only a few projects have the honor to enter the "10th Five-Year Plan" of the "863 Program." The National Natural Science Foundation of China no longer favors the diamond film project alone. Many domestic diamond film research groups have felt the threat of survival more or less. Many units have turned to more novel and fashionable - C3N4, carbon nanotubes, fullerenes, or DLC closer to industrial applications. However, even in such an environment, domestic CVD diamond film research has not stopped.

( 5) Major events during the “10th Five-Year Plan” period (2001-2005 )

1. Preparation of nano-diamond (NCD) films (grain size less than 200 nm) and ultra-nano (UNCD) diamond films (grain size less than 20 nm), and related electronics, friction and wear, and electrochemical applications have arisen in China. And become a new highlight of the Natural Science Foundation funded project;

2. The momentum of diamond film industrialization continued to strengthen: Beijing Tiandi Company finally passed the key “profit and loss point” and began to make profits; Jilin University took over the diamond film enterprise of Beijing Institute of Technology in Jinzhou (the company was not adopted by Beijing Institute of Technology) The industrialized verification of DC Arc Plasma Jet technology failed, the local government required the 863 expert group to intervene), and announced that it cooperated with Huanghe Group, the largest high-temperature and high-pressure synthetic diamond company in China, to establish the diamond film industry; Shanghai Jiaotong University established a special diamond film. The company coating large-diameter wire drawing die, and successfully applied nano-diamond film coating technology; the Ministry of Nuclear Industry's nine hospitals used the military-to-civilian project funds to establish a diamond film enterprise, and the diamond film coated large-aperture hard alloy The wire drawing die is used for the industrial production test of cold drawn high-strength steel wire; the Hebei Academy of Sciences began to promote the diamond self-supporting film drawing core produced by the DC Arc Plasma Jet CVD method in China, and sold the newly developed 30 to some domestic research institutes. Kilowatt production and R&D equipment (based on the cooperation with Beijing University of Science and Technology) Preparation 100 kilowatt reduction research DC Arc Plasma Jet CVD system, simplification and improvement);

3. Application research is further strengthened: Beijing University of Science and Technology has prepared 60mm×0.6mm optical grade diamond self-supporting film polishing window sample, which is close to the type IIa natural diamond single crystal (Raman half height 3.2cm ^-1 , 8-12 m m transmittance is 70.6%, thermal conductivity is 20W/cm.K, Tan: 3×10 ^-4 (35 GHz), but in the ultraviolet region (220-400 nm) and the optical fiber of E6 company prepared by microwave plasma CVD in foreign countries Compared with the grade diamond film, there is still a clear gap. It has begun to attract the interest of some application units in the domestic aerospace and electronics industry; Jilin University has carried out research on SOD anti-radiation devices, showing application prospects in a series of important technical fields; progress in diamond radiation (particle) detector research, The prototype device has a charge collection distance of 12.5 m and a charge collection efficiency of 60%. BDD (boron-doped diamond film) electrodes were prepared on Si, Ti and other materials, and wastewater treatment using BDD was carried out.

The biggest highlight during the “Eleventh Five-Year Plan” period (2005-2010) is that CVD diamond film research has finally embarked on the right path of industrial application.

( 6) In basic research and applied research

1. With the advent of the graphene research boom, some people turned. Guangzhou Nonferrous Institute stopped the development of CVD diamond film and turned to the industrial application of DLC;

2, nano (NCD) and ultra-nano (UNCD) diamond film preparation and related applications research boom has not been reduced;

3. With the introduction and preparation technology advancement of foreign advanced (Seki) advanced microwave plasma CVD equipment, Jilin University, 12 electronics group, Oriental Tiandi Company and other units have announced the preparation of optical grade diamond self-supporting film, the largest size of 2 inches. (50mm). At the same time, Beijing University of Science and Technology used high-power DC Arc Plasma Jet CVD optical grade diamond film to complete the comprehensive performance test and research for aerospace and other high-tech applications, including Raman FWHM and impurities (nitrogen). Content, UV, visible and infrared absorption, microwave dielectric loss (Tan d ), thermal conductivity, fracture strength, fracture toughness, resistance to high temperature oxidation and protection, sand erosion resistance, thermal shock resistance, laser damage resistance, and high temperature radiation Series performance data such as coefficients. And an optical grade diamond self-supporting film window of Φ120mm and a maximum thickness exceeding 2mm is prepared;

4. Jilin University adopted the microwave plasma CVD method to start the high-speed growth of CVD diamond large single crystals in China. The Beijing University of Science and Technology followed up, but adopted high-power DC Arc Plasma Jet CVD technology; (5) Nanjing Airlines Aerospace University, Beijing University of Science and Technology, Jilin University, etc. have announced the successful preparation of curved (spherical) diamond self-supporting film samples.

( VII) During the “Eleventh Five-Year Plan” period (2005-2010 ) , the industrialization of CVD diamond film showed a gratifying new weather.

1. CVD diamond film production enterprises have rapidly expanded to more than 20, with only 5 in Beijing;

2. After hot-wire CVD (EACVD), DC Arc Plasma Jet has become one of the main technologies for the domestic industrialization of CVD diamond film, forming a situation in which two technologies compete;

3. Beijing University of Science and Technology and Hebei Academy of Sciences jointly established Hebei Plessman Diamond Technology Co., Ltd. in 2009. The company's output value reached more than 7 million yuan in the year, and almost all of its products were sold to Europe and America. The company's tool-grade diamond self-supporting film is produced by 30 kW DC Arc Plasma Jet CVD. It has high strength, high wear ratio and brown transparency after polishing. It is called “Brown Diamond” by foreign customers. Part of the E6 tool-grade diamond film product was replaced in the European and American markets. In 2010, the annual output value rose rapidly to about 11 million yuan, of which the domestic market accounted for about 20%;

Second, the status quo

Since entering the "Twelfth Five-Year Plan" (2011-2015), the research and application of CVD diamond film continues to pick up.

( 1) In basic research and applied research

1. Research on the preparation and related applications of nano- (NCD) and ultra-nano (UNCD) diamond films continues the development momentum of the past few years;

2, CVD diamond single crystal growth began to achieve results: Jilin University using microwave plasma CVD method, using CO ₂ and N ₂ O (laughing gas) to achieve high-speed growth of CVD diamond single crystal (maximum growth rate of 135μm / h), they also It is reported that the growth rate can reach 200 μm/h; Beijing University of Science and Technology successfully grows a high quality diamond single crystal layer with a size of 7.5 mm × 7.5 mm × 1.03 mm (weight 1.13 carats) using a 30 kW DC Arc Plasma Jet CVD. 400) The diffraction peak single crystal rocking curve has a full width at half maximum of 9.8 arc seconds, a Raman half width of 1.9 cm ^-1 , and a nitrogen content of about 6 ppm (from industrial pure hydrogen and methane used);

3. In addition to infrared window and dome, high-power traveling wave tube heat-dissipating support rod, surface acoustic wave device (SAW), SOD (radiation-resistant electronic device), nuclear technology (Gyrotron) window and radiation detector) application, space environment High-end applications such as detection and sensing have attracted the attention of relevant domestic application departments, and some projects have been researched.

( 2) In the industrialization and market of CVD film

1. The annual output value of Hebei Presman Diamond Technology Co., Ltd. reached 22 million yuan in 2012. The annual output value has increased by 2 times in the three years from 2009 to 2012, with an average annual growth of over 50%. It currently has more than 30 sets of 30 kW DC Arc Plasma Jet CVD equipment with a capacity of over 7 million cubic millimeters (120,000 carats), covering tool-grade, heat sink and optical grade diamond self-supporting film products. In 2012, the domestic market sales volume has risen to over 30%;

2. The heat sink grade CVD diamond film began to appear as a fixed customer, and the optical grade diamond self-supporting film and window began to be sold in small quantities (Hebei Presman Company);

3. Shanghai Jiaotong University's diamond film coated deep-hole hard alloy wire drawing die has annual sales of more than 10 million;

4. Xiboer Company exhibited 250mm×250mm large area hot wire CVD diamond self-supporting film;

5. Microwave plasma CVD technology has finally begun to make great progress. In the 23 years from 1987 to 2010, domestic microwave plasma CVD equipment has remained at the level of foreign countries from the late 1980s to the early 1990s. Around 2007, Chengdu Electronics University of Science and Technology developed a 5-kilowatt ellipsoidal microwave plasma CVD apparatus, which was sold to Tsinghua University, but has not been functioning properly. In the three years from 2009 to 2012, Beijing University of Science and Technology began to design and build an 8 kW ellipsoidal cavity microwave plasma CVD system and a 5 kW class air intake tunable cavity microwave plasma CVD. system. The former has reached the level of foreign countries in the late 1990s, and the latter has improved compared with the resonant cavity design of the current microwave plasma CVD system abroad. At present, the 8-kilowatt ellipsoidal cavity microwave device has been delivered to Hebei Presman Company for the development of optical grade and electronic grade diamond self-supporting membranes; the latter has also been delivered to domestic users.

Third, the existing problems

Reviewing the bumpy history of CVD diamond film research and application in China for more than 20 years, it is gratifying to build a high-level CVD diamond film research and development team from scratch, forming a CVD diamond film industry, and has begun to develop. The process of growth. But there are also some problems as follows:

(1) From the perspective of the government and management departments, the idea of ​​quick success and instant benefit has seriously affected the progress of research and application of CVD diamond film in China. In the initial research start-up and team building period, basic research and capacity building (including equipment and research teams) were not carried out in a down-to-earth manner, but the application and industrialization were emphasized prematurely. As a result, a large number of applied research is basically carried out at a lower level of preparation. Although it has no effect on the publication of the paper, it has hardly promoted the application and industrialization.

(b) For the same reason, the “863 Program” expert group did not put the development and update of preparation methods and equipment in an important position due to the eagerness of the government and management departments to make a high-quality, large-area diamond film preparation. It has always lagged behind foreign standards. A typical example is microwave plasma CVD, which has not been supported by the “863” and other government-funded programs for more than 20 years. Although DC Arc Plasma Jet was funded by the “863 Program” major project, the maturity of this technology was more than 10 years of effort after the “863 Program” ceased the special funding and there was almost no major national project support. Only gradually achieved. The development of industrial equipment for hot-wire CVD (EACVD) and hot cathode CVD methods and the preparation of large-area diamond film are also achieved through continuous and painstaking efforts by the relevant units without the continued support of the “863 Program”. . Without the insistence of these units, it is difficult to imagine that the industrialization of CVD diamond films will reach the current level.

(3) The lack of industrialization mechanism to realize research projects is another important reason hindering the industrialization of diamond film. National projects, including the “863 Program” project, can only support the feasibility study and prototype device (product) development phase, while the subsequent pilot and industrialization are broken. Most of the entrepreneurs in our country adopt the attitude of “not seeing rabbits and not hawking” and are unwilling to bear the risks in the process of industrialization. The low secondary research and development capabilities of the company itself are also possible reasons. At present, as the CVD diamond film industry has begun to show a benign development trend, the situation has been significantly improved.

(4) In terms of technology and competition. Although the performance of CVD diamond film is very high, it is almost unmatched by other materials. Because the cost of preparation and processing of diamond film is still high, and in many cases, diamond film is not the only choice, so its cost performance is still a big problem. . The specific brief description is as follows:

1. Tools and friction and wear applications: The current tool-grade diamond film products are basically limited to trimming and drawing cores, replacing natural diamonds, and subject to competition by PCD, so the market size will not be large. Precision cutting tools have been considered a good market direction, but they face the impact of high-end natural and synthetic diamond single-crystal tools and low-end PCD tools, and because of the columnar crystal characteristics of polycrystalline diamond films, only suitable In the production of low-end tools, it is difficult to take advantage of product positioning and cost performance. Due to the wide application range and low preparation cost, diamond film coating tools have much room for development. However, the current domestic market is still limited to large-size deep-hole carbide drawing die. Diamond film coated carbide metal cutting tools are still not available in large quantities.

2. Thermal application: The thermal conductivity of diamond film is the highest among all known materials, and the potential market scale is large. However, due to the limitation of cost performance, only a small number of products are currently sold. Due to the high cost of diamond film preparation and processing, diamond films currently have no competitive advantage except for individual applications. In recent years, composite materials such as diamond/copper and diamond/aluminum have a moderate thermal conductivity compared to other heat sink materials, and the thermal expansion coefficient is close to that of metal materials such as copper and aluminum, and electronic devices (or The system) is more compatible and has become a strong competitor to the diamond film heat sink.

3. Electronics applications: Due to the failure of large-area diamond film heteroepitaxial diffusion and the difficulty in n-type doping, diamond high-temperature semiconductors are no longer the mainstream of current high-temperature semiconductor research. Although the semiconductor performance of SiC is far less than that of diamond, large-size SiC single crystals are easier to grow than diamonds and have better compatibility with existing silicon semiconductor technologies. Therefore, SiC at home and abroad is the mainstream of research, and diamond is not a reasonable choice.

4, optical applications: In extreme applications, CVD diamond film has obvious advantages, in some cases may be the only choice. The problem is that the actual application is very demanding for the quality of the diamond self-supporting film (requires optical pole), size and thickness, shape (such as dome), and the application environment. The technical difficulty is very imaginable. In the past 10 years, due to the existing materials such as sapphire (3-5μm medium wave infrared window material) and ZnS (8-12μm long-wave infrared window material) can basically meet the application requirements, there is no engineering application of optical grade diamond film. Put it on the agenda. After entering the "Twelfth Five-Year Plan", it was discovered that for the development of future technologies, diamond film has become the only choice in some important application fields. However, due to the lack of sufficient financial support for a long time, it is easy to realize the engineering application of optical grade diamond film in a short period of time. In any case, this has injected new vitality into CVD diamond film research. However, from the perspective of industrialization, the market size will not be large.

Fourth, the outlook

Although CVD diamond film research has been more than 30 years old, there are still new highlights and new research directions. They will be the recipients of the Natural Science Foundation of China and other types of basic research programs. Nano (NCD) and ultra-nano (UNCD) diamond films and related applications will continue to be one of the hotspots of domestic CVD diamond film research for a long time. Based on NCD and UNCD-based MEMs and NEMs, electronics applications, electrochemical applications, and biomedicine and sensors are likely to be the highlights. Epitaxial growth of CVD diamond single crystals will soon become a new hot research direction in China. Relevant electronic applications, high-performance particle detectors, and high-pressure physics experiments will soon appear. Microwave plasma CVD equipment and technology will be further developed, gradually getting closer to the gap between foreign equipment and technology. Electronic grade diamond self-supporting films will soon appear in China and will be used in high power microwave windows and high performance particle (radiation) detectors. Based on diamond film SOD, SAW, traveling wave tube and other high-power devices, high-tech applications such as optical window (ball cover) will likely receive more attention, and may be practically applied in the next 5-10 years. It is possible to form a small-scale market.

Although the diamond self-supporting film tool application market is limited, it seems to have begun to take shape. The domestic large-scale market has just begun to form, and there is still a considerable distance from the saturation of domestic and foreign markets, and there is considerable room for development and space. The application of diamond film coating tools has not yet opened the door to the market. The existing market application (large aperture deep hole diamond film coated carbide brushing die) is only a special case. The development space and space will depend on the further development of technology. And product and technology research for real-world application needs, as well as market development. The potential market for diamond film heat sink applications is very large, but the prospects in the near future are not clear. It has been difficult to greatly reduce the preparation cost of the heat sink grade diamond film by relying on existing technologies. However, there is still a market of a certain size in special applications where high thermal conductivity is emphasized and cost performance requirements are reduced. The market for heat sink grade diamond films at home and abroad will gradually expand, but it will not form a large scale until the production cost is greatly reduced. The market for optical grade diamond films will also gradually increase, but due to the particularity of the application, it is unlikely to form a large-scale market. CVD diamond large single crystal may become a dark horse in the domestic diamond film market. It is possible to form diamond single crystal precision cutting tool and CVD diamond diamond ring market in the next 5 years, which may affect the order of diamond ring market at home and abroad (if anyone uses it) To pretend to be a natural diamond ring).

V. Conclusion

The research and application of CVD diamond film has been concerned by many research and application departments at home and abroad, as well as government agencies, and has given great expectations. However, due to the poor performance of several applications with the highest expectations (high temperature semiconductors, diamond film coating tools and heat sinks, etc.), the research and application of domestic CVD diamond films have experienced bitterness and frustration, and once faced unsustainable Dilemma. Due to the continuous efforts of the domestic CVD diamond film research industry, it has finally passed through the difficulties, and there has been a gratifying situation and good development momentum in research and industrialization. The author has been working in this field for more than 20 years, and has participated in and witnessed the entire historical process of China's CVD diamond film from birth to growth. This article is specially made to share the domestic research and application field of CVD diamond film. For a long time, memory errors and inadequate research and research are inevitable! (Author: Professor Lu Fanxiu Beijing University of Technology, this article is taken from "Chinese diamond industry fifty years" lower)