Dust adhered to the integrated circuit may cause open or short circuit, and the dust directly affects the product yield. Today, the semiconductor industry (chip factory) is highly critical about the cleanliness of the production environment and the most demanding air filters.
One of the indicators for measuring chip integration is line width, which is the width of the wires on the circuit. In the era of calculating the line width in micrometers, people said that the limit of the particle size of the manufacturing environment is less than 1/10 of the line width. As the line width continues to decrease, the 1/10 becomes 1/4, 1 / 2. In 2002, the line width of the P4 processor in ordinary microcomputers was reduced to 0.13mm. At this time, any dust may damage the circuit, and the traditional comparison of particle size and line width is outdated.
The traditional ventilation mode of the chip factory is a large circulation. The entire ceiling of the workshop is covered with high-efficiency filters, and the entire floor is a return air grille. At present, some workshops of chip factories use the filtering device with built-in fan, namely FFU. Both large circulation and FFU can achieve sufficient cleanliness, but there are differences in operation management and energy consumption.
Whether it is an ordinary high-efficiency filter or FFU, it must be scanned one by one before leaving the factory. There is currently no standard for scanning test methods in China. Filter manufacturers that can squeeze into chip factories perform scanning tests on filters according to European and American standards. The chip factory believes that the test dust used in the traditional filter inspection method is itself a source of pollution, so the chip factory does not buy the sodium flame method and the DOP method.
Sea salt particles in the air are the enemy of all electronics industries, but the particles of sea salt dust in the air are relatively large, and ordinary filters can filter them out. Some people say that the ideal place for the electronics industry should be far from the coast, but the coastal areas have developed economies, and chip factories have been built in coastal areas in a swarm. Just spend more money on filters.
In the early 1990s, foreign countries had quarreled about the boron content of high-efficiency filter glass fiber filter paper. Then, the trace volatile elements of the filter became a concern of chip manufacturers. In recent years, high-efficiency polytetrafluoroethylene fiber filtering materials have appeared in foreign countries. This material has no volatiles, but it is an electrostatic electret, which has fewer hidden dangers and more trouble. The filtered air must be Electrically neutralize to remove ions from the air. At present, the price of this material is relatively high, and most filters still use glass fiber filter paper. The possible trace volatile elements on the filter mainly come from the binder and cleaning agent, and the filter manufacturers supplying the chip factories need to work on this.
Today's filtration technology can reduce the dust concentration in clean rooms to almost zero, as clean as you want. When the line width on the chip is as small as 0.5mm, it is found that chemical pollutants in the air have become a major hazard that affects the yield rate. Therefore, chemical filters are commonly deployed in chip factory air conditioning systems with line widths less than 0.5mm. The principle and manufacturing process of chemical filters are not complicated. They are activated carbon filters, but traditional activated carbon filter manufacturers and military factories have not taken the chip factory. Most of the chemical filters in chip factories are made of air-conditioning filters. Provided by the manufacturer.
The sources of chemical pollutants may be: outdoor air, the process itself, people, and decoration materials. In most cases, designers and field personnel can't tell the type and concentration of pollutants. Therefore, the chemical filters provided for them should have at least two characteristics: broad-spectrum adsorption performance and sufficient activated carbon materials. The so-called broad-spectrum adsorption means that it can adsorb more or less on everything, and the most common and cheapest granular activated carbon can have this function. If the types of pollutants can be determined, targeted chemical treatments can be performed on the activated carbon materials to enhance the ability to adsorb specific pollutants. Filter suppliers sometimes also provide corresponding on-site testing services to help users determine the use of chemical filters. This requires suppliers to have experts in chemical filtration and has a close relationship with well-known chemical laboratories. . Unfortunately, few domestic filter manufacturers are working on it, so most of the chemical filters currently used by domestic chip factories are imported products.
The semiconductor industry is not generally considered a "smoke-free industry", it also has environmental issues. The latest technology and materials are often used there. Some chemicals have been used in large quantities before their safety has been evaluated. A little carelessness will cause serious chemical pollution, both groundwater pollution and air pollution. This paid an amazing price. For insurance purposes, some companies also use chemical filters in their exhaust systems.
China is in the midst of a new round of chip factory construction. To this end, China will need hundreds of millions of dollars of high-efficiency filters and chemical filters in the next few years. If domestic filter vendors are just as keen on plagiarism, suspicion, Gu is busy in various places, not technically enterprising and not communicating with each other, this rare market of chip factories will belong to outsiders.