The front-end of line (FEOL) is the processing process of the wafer fabrication plant, where the circuit is processed on a blank silicon wafer, and the factory product is still a complete round silicon wafer. It is one of the most critical links in the entire chip production process. The chip front-end process involves chip preparation, lithography, etching, thin film growth, ion implantation, cleaning, CMP, measurement and other processes; If there is a problem in these links, it will affect the entire chip production process.
First, the process of the chip front-end process
1. Preliminary preparation
Before chip production, it is necessary to prepare materials, inspect equipment, and arrange production plans.
2. Wafer preparation
In chip manufacturing, wafers, as the basis of chips, need to undergo scribing, grinding, polishing and other processing processes to meet the requirements of surface flatness and thickness.
3. Thin film deposition
In chip manufacturing, a variety of thin film deposition technologies are required, such as chemical vapor deposition (CVD), physical vapor deposition (PVD), sputtering, etc., to achieve the smoothness and corrosion resistance of the chip material surface. The SiO2 thin film layer formed on the surface of the silicon wafer is processed into the required shape, and a series of processes such as oxidation, photolithography, etching, and degumming are carried out. The diagram below illustrates a standard process, where the first step of film formation is mostly deposition (CVD, PVD, etc.), with only a small amount of oxidation.
4. Photolithography
Lithography technology can transfer the circuit pattern of the chip to the photoresist, so that the subsequent process process can be etched, deposited and other processing, so as to form the circuit structure of the chip. After gate oxide and polysilicon deposition, photolithography and etching, the pattern in the diagram is formed, and the gate is processed. Note that gate processing also goes through the process of photoresist, lithography and development, which are omitted in the figure below.
Ion implantation is preceded by gluing, photolithography and development, where the area to be protected is covered with photoresist and then ion implantation is performed to process the source and drain.
Finally, in the manufacturing process of metal contact holes and wires, it is generally necessary to process the insulating layer and the metal wire layer separately.
5. Cleaning
The cleaning process is an important part of chip manufacturing, which aims to clean the film based on different processes to ensure the stability and consistency of chip quality. At the same time, CMP and cleaning are usually performed after the process in preparation for the next round of the process.
6. Measurement
Measurement and inspection work at every critical step.
Second, the key technology of the chip front-end process
1. Wafer preparation technology
Wafer preparation technology is directly related to the flatness of the chip surface and the stability of quality.
2. Thin film deposition technology
Thin film deposition technology is an important part of chip manufacturing, which requires the use of appropriate vapor deposition, physical deposition technology and other processing methods to achieve the smoothness, uniformity and chemical properties of the material surface.
3. Lithography technology
Lithography technology is one of the key processes in chip manufacturing, which needs to fully consider factors such as the resolution, depth, and line width of the circuit pattern.
4. Cleaning technology
The cleaning process is an important part of chip manufacturing, which requires the use of water washing, pickling, alkali washing and other methods to ensure that the surface of the chip is clean and free of impurities.
3. The significance and importance of the chip front-end process
The significance and importance of the front-end process are mainly reflected in the following aspects:
1. The formation of the infrastructure
The front-end process is the initial stage of chip manufacturing, and its core task is to form basic circuit components such as transistors. These basic components are the basis for the subsequent circuit function implementation, and if the front-end process is inaccurate or incomplete, it will directly affect the overall performance and reliability of the chip.
2. Precision and miniature technology
With the development of Moore's Law, chip process nodes continue to shrink, requiring precise control of front-end processes at the nanometer level. For example, the implementation of 7nm, 5nm, and even 3nm process nodes is highly dependent on the refinement and precision of the front-end process. This high-precision manufacturing capability is the key to the advancement of semiconductor technology and the improvement of chip performance.
3. Material and process innovation
Front-end processes involve a great deal of material science and process innovation. For example, the introduction of new materials and structures, such as high-kappa materials, metal gate technology, and FinFET structures, all need to be realized through front-end processes. These innovations are important means to improve chip performance, reduce power consumption, and increase integration.
4. Cost and yield management
The complexity and precision of the front-end process directly affect the cost and yield of chip manufacturing. Optimizing the front-end process can not only reduce production costs, but also improve yield and increase production efficiency. Efficient front-end process management is of great significance to the economic benefits of the entire semiconductor industry chain.
5. Technical competitiveness
Leading front-end process technology is an important part of the core competitiveness of semiconductor enterprises. Mastering the advanced front-end technology can enable enterprises to occupy a dominant position in the fierce market competition and gain more market share and technical discourse.
To sum it up
The chip front-end process is one of the key links in the entire chip manufacturing process, involving multiple processes and technologies. Only on the basis of reasonable arrangement of production processes and technical paths can we produce chip products with high quality and stability.
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