During the production process of semiconductor device wafers, it is easy to be affected by foreign objects, dust particles, metal ions and other foreign objects to destroy the surface structure. This product characteristic also determines the cleanliness requirements in the manufacturing process. At the same time, during the testing of semiconductor wafers, the test room must also be placed in a clean room. The control of cleanliness is also important. Poor control of the cleanliness of the clean room will result in excessive dust content in the air. This leads to an increase in foreign objects, which in turn affects the accuracy and stability of the test. In severe cases, it will cause damage to the probe test card.
Key Points of the Design and Layout of Semiconductor Wafer Workshop
The main function of the clean room is to control the cleanliness, temperature and humidity of the atmosphere that the products (such as silicon chips, etc.) contact, so that the products can be produced in a good environmental space. In the wafer workshop, in order to solve the problems of poor yield during wafer testing, unstable test results, damage to probe test cards and scrap of wafers, the design of clean rooms and auxiliary rooms should be the first priority for plant construction. One of the tasks.
The larger the wafer production enterprises, the higher the requirements for the automation and intelligence of the entire factory. Therefore, for the designers of the semiconductor clean production workshop, what kind of reasonable planning and systems should be made in the wafer plant area with an investment of tens of billions? Setting up to improve the space utilization of the entire clean factory, reduce the idle time of the machine, and improve the yield of the product is the top priority of their design. Of course, these contents are also issues that need to be discussed and researched with the manufacturer before the factory design is finalized.
The wafer workshop has strict control requirements for the temperature, humidity, cleanliness, and anti-microvibration of the production environment, and various supporting systems are numerous and complicated. Designers will also use FAB layout design routinely.
Most FBA factories have a four-layer structure, from top to bottom: upper technical interlayer, clean production layer, clean technical interlayer and non-clean technical interlayer.
Key points of design indicators and parameters:
1. Because of its high requirements for constant temperature and humidity control in the production environment (temperature control at 22℃±1℃, relative humidity control at 43%±3%);
2. The air cleanliness level of the production environment is 1,000 (ISO 6);
3. The air purification level of special areas such as lithography is level 10 (ISO level 4);
4. The specification requires that the clean room with air purification level (ISO 1-4) adopts vertical laminar flow: the air in the upper technical mezzanine (air supply static pressure box) is transported to the clean production layer through the FFU (fan filter unit), and the air flows through The raised floor and the holes of the waffle board are sent to the clean technical mezzanine, and then go back to the upper technical mezzanine through the DCC (dry cooling coil) in the return air duct.
In addition, the Fab factory uses a large number of flammable, explosive and toxic chemicals, and there are many types. Therefore, the designer should pay special attention to the design of Class A and B gases, hazardous chemicals, and even inert gas storage and distribution rooms according to the specifications during the design process. The outdoor space corresponding to the storage and collection room for acidic, alkaline, and organic chemicals should be arranged against the external wall, and sufficient tank truck loading and unloading area should be reserved. Fire protection design is the difficulty and pain point of Fab factory design. Designers have to invest a lot of energy in fire protection zone design, explosion prevention design, and the setting of special fire exits. The four specifications of "Silicon Integrated Circuit Chip Factory Design Code", "Building Design Fire Protection Code", "Electronic Industry Clean Factory Design Code", "Clean Factory Design Code" are the main specifications for wafer shop design, and each designer needs to study Thoroughly and practice as a design basis.
