Essential knowledge of IC testing

IC Industry Business Model

From IDM to vertical division of labor, specialized division of labor in the IC industry has led to the emergence of independent testing vendors. The integrated circuit industry has gradually emerged since the 1960s, and early companies used the IDM operation model (vertical integration), which covered the entire chip production process of design, manufacturing, packaging and testing. These types of companies generally have the characteristics of large-scale, comprehensive technology, and deep accumulation, such as Intel, Samsung, etc. With the increasing cost of technological upgrades and the increasing demand for production efficiency in the IC industry, the entire industry is gradually moving towards a vertical division of labor model.

In 1987, TSMC was founded, which separated IC manufacturing from the IC industry and gradually developed into an industrial chain model that separated design, manufacturing, packaging, and testing. This vertical division of labor model greatly improves the operational efficiency of the entire industry; Secondly, separating the design of relatively light assets from the manufacturing and testing of heavy assets is beneficial for concentrating research and development investment in each link, accelerating technological development, and reducing the entry threshold and operating costs of enterprises; Furthermore, each link is entrusted to different manufacturers to enhance the professionalism of the enterprise and the accuracy of the production process. In addition, separating professional testing from sealed testing can not only reduce duplicate production capacity investment, but also provide stable professional testing services for small and medium-sized design manufacturers, reducing product testing costs and industry costs through economies of scale.

IC testing and division of labor

IC (Integrated Circuit) testing is located at key nodes in the industry chain, running through the entire process of design, manufacturing, packaging, and application. From the perspective of the entire manufacturing process, integrated circuit testing specifically includes design verification in the design phase, process technology inspection in the wafer manufacturing phase, wafer testing before packaging, and finished product testing after packaging. It runs through the entire process of design, manufacturing, packaging, and application, and plays an important role in ensuring chip performance and improving the efficiency of the industrial chain operation.

Design verification, also known as laboratory testing or characteristic testing, is the verification of the correctness of the design before the chip enters mass production, which requires functional testing and physical verification.

Process technology testing, also known as testing during wafer manufacturing, requires the detection of defects, film thickness, line width, critical dimensions, etc., which belongs to pre testing.

Chip Probing, also known as in chip testing, is a process of testing a wafer that has been manufactured by a foundry. The purpose is to remove any defective chips before slicing and packaging, in order to reduce packaging and chip product testing costs. At the same time, it calculates the pass rate of chips on the wafer, the exact location of non-conforming chips, and various forms of pass rates, which can directly reflect the wafer manufacturing yield and test the wafer manufacturing capability.

Final Test (also known as Final Test) for chip products, involves the process of slicing, bonding, packaging, and aging in the subsequent stages of integrated circuits, which can damage some circuits. Therefore, after packaging and aging, a comprehensive circuit performance test should be conducted on the circuit products according to the test specifications. The goal is to select qualified products, classify them according to the parameter indicators of device performance, and record the number of devices at all levels and the statistical distribution of various parameters; Based on this data and information, the quality management department supervises the quality of the product, while the production management department controls the production of the circuit.

IC testing is an important step in ensuring product yield and cost control, and plays a crucial role in the IC production process. IC testing is an important part of the integrated circuit production process. The main purpose of testing is to ensure that the chip can fully achieve the functions and performance indicators specified in the design specifications in harsh environments. Each test will generate a series of test data. As the test program is usually composed of a series of test items, the chip is fully tested from various aspects. Not only can it determine whether the chip performance meets the standards and whether it can enter the market, but it can also fully and quantitatively reflect various indicators of each chip from structure, function to electrical characteristics from the detailed data of the test results. Therefore, testing integrated circuits can effectively improve the yield and production efficiency of chips.

Design verification and process control testing are difficult to independently divide labor, and wafer testing and chip finished product testing are the main business forms of professional testing companies. The design verification part is difficult to outsource due to the issues of information confidentiality and low market demand, while process control testing has high requirements for cleanliness and stability in the production process, making it difficult to independently divide tasks. Wafer testing and chip finished product testing belong to the middle and back testing parts, and their information confidentiality and production environment control requirements are relatively low. In addition, the independence and professionalism of third-party testing vendors can ensure the validity of test results and timely feedback to upstream, improving chip production efficiency. Therefore, most design and manufacturing manufacturers currently outsource wafer testing and chip finished product testing to third-party professional testing vendors.

IC testing trends

The rapid growth of the industry is driven by upstream prosperity, refined division of labor, and independent and controllable demand. The potential market space for domestic IC professional testing is large, and there are deterministic opportunities. In recent years, the entire IC industry in China has developed rapidly. In terms of IC manufacturing, the country has focused on investing in the construction of a large number of wafer factories and expanding production lines.

The cost advantage of scale is obvious, and the trend is towards specialized testing. The IC industry continues to highly refine its division of labor, and the trend towards specialization in chip testing is bound to be inevitable. Firstly, the evolution of IC processes and the increasing complexity of processes require higher requirements for parameter control and defect detection during the manufacturing process, leading to an increasing demand for specialized IC testing; Secondly, chip design tends to be diversified and customized, and the corresponding testing plans are also diversified, which increases the requirements for testing talents and experience. Therefore, testing outsourcing is beneficial for reducing the burden on small and medium-sized enterprises and increasing efficiency. In addition, professional testing has certain cost advantages. At present, the testing equipment is mainly imported, with a single machine value ranging from $300000 to $1 million. Domestic IC design companies are more inclined to choose mainland testing vendors due to considerations of cost coordination and domestic autonomy in OEM, packaging, and testing processes. Domestic IC design companies face high transportation and communication costs in the process of connecting with overseas testing manufacturers, including contract manufacturers. At the same time, considering the independent and controllable aspects of wafer contract manufacturing, packaging, and testing in China, design manufacturers are more inclined to choose mainland testing manufacturers when professional IC testing services can be provided domestically.

The development of upstream has also driven the development of domestic testing equipment manufacturers. In recent years, the technology of domestic testing equipment such as probe stations and chip testing has also been greatly improved, and a group of emerging testing equipment manufacturing enterprises have emerged. For example, Shenzhen Taike Optoelectronic Technology Co., Ltd. has reached the advanced level in domestic technology in probe stations, chip testing machines, blue film ribbon machines and other equipment, gradually catching up with foreign brand products, and is in the early stage of catching up with domestic professional testing equipment. The company that is the first to achieve breakthroughs has a clear first mover advantage.

IC testing market

After capital mergers and acquisitions, the domestic sealing and testing industry has entered the top tier of global sealing and testing, with a stable market share in the top three.

The market share of independent professional testing has been increasing year by year. IC testing runs through the entire process of chip manufacturing, which is of great significance in ensuring the performance and stability of chips. Independentization of testing not only helps to improve its professionalism, but also enables timely analysis and feedback of existing problems in chip design and manufacturing, reducing capacity waste, effectively reducing production costs, and improving efficiency. Therefore, the proportion of independent professional testing in global IC testing has been increasing year by year.

The domestic professional testing field is still in the early stage of catching up, and small and medium-sized testing companies are rapidly developing. At present, the professional testing of IC in China is still in the early stage of development, and dozens of small and medium-sized testing companies are rapidly developing with the rise of upstream design and manufacturing processes. However, compared with mature enterprises such as Taiwan's Kywon Electronics, domestic IC testing companies still have a significant gap in scale and technology. The ability to develop independent testing solutions and rich testing experience constitute technical barriers.

The IC testing program is cumbersome and requires high standards. Wafer testing and finished product testing are essentially electrical performance tests of integrated circuits, including the electrical characteristics, electrical parameters, and circuit functions of the chip. Among them, function is the behavior (ability) of the device, characteristic is the manifestation of device behavior, and characteristic parameters are the main characteristics of the device. Therefore, electrical performance testing is the examination of the electrical characteristics, parameters, and functions of integrated circuits under different conditions. In addition, a series of testing specifications will be adopted during the IC testing process to improve the level of integrated circuit design, process control, and usage, including characteristic specifications, production specifications, user specifications, and end-of-life specifications, which correspond to the allowable limits of chip working conditions and the evaluation of circuit performance compliance, online testing during the production process, user acceptance testing, and reliability evaluation.

The focus of technical research and development is on developing testing programs and testing solutions. The testing program during the wafer testing phase is the process control program. The developed control program is input into the machine to test the wafer. The testing program during the finished product testing phase is developed based on chip functional testing, usually by burning the program on the chip and conducting functional testing. The development of testing plans is based on the combination of different testing types, chip types, and other testing machines to improve testing efficiency. For example, wafer testing is the combination of probe stations and testing machines, which can achieve and optimize the testing of wafers of different sizes and process technologies, while finished product testing is the combination of sorting machines and testing machines.

Write at the end

IC testing requires a lot of experience accumulation. Testing enterprises rely on talent, equipment, and experience, and require continuous research and development to adapt to new process and process requirements. In terms of research and development, IC testing is constantly updated with the diversification of chip products and the development of Moore's Law. Testing companies need to constantly research and develop, introduce, and debug new testing platforms to meet the testing needs of new products, processes, and processes; In terms of talent, IC testing runs through all aspects of chip production. Test engineers not only need to have testing related abilities such as test plan development and equipment debugging, but also need to have knowledge and experience in chip design, manufacturing, and other fields. Currently, there is a clear shortage of integrated circuit talents in China, and the training of test engineers is weak. Talents with market-oriented experience are even rarer; In terms of equipment, currently the main reliance is on imported testing equipment from abroad. In recent years, domestic testing equipment manufacturers have also gradually occupied local markets. For example, Shenzhen Tech Optoelectronics has made great progress in technology and research and development of probe stations, chip testing machines, blue film braiding machines, and spectrophotometer braiding machines, which are at the forefront of China. The gap with imported products is constantly narrowing, gradually penetrating the market; In terms of experience, IC testing, like traditional manufacturing, requires a process of capacity ramp up and process optimization, requiring testing experience for different customers and products.

Part of the content comes from "Semiconductor Industry Observation and Changqing Economic Research Institute"