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With the continuous and steady growth of China's national economy and the constant innovation and development of production technologies, the production process has become increasingly demanding on the production environment. The upstream and downstream processes in large-scale and ultra-large-scale Ic production put forward higher requirements for the production environment, not only to maintain a certain degree of temperature, humidity, and cleanliness, but also to pay enough attention to electrostatic protection.
As we all know, the packaging industry is a post-production process in the entire IC production. In this process, for plastic ICs, hybrid ICs, or monolithic ICs, there are mainly wafer thinning (grain polishing), wafer cutting (dicing), On the core (stickies), pressure welding (bonding), packaging (encapsulation), pre-curing, plating, printing, post-curing, cutting ribs, tube, post-sealing test procedures. Each process has different requirements for different process environments.
Effect of electrostatic factors on IC package
First, the cause of static electricity is everywhere. With the rapid development of science and technology and highly automated industrial production, the harm of static electricity in industrial production is already obvious. It can cause various obstacles, limit the improvement of automation level and influence product quality. Here we combine the actual conditions of the IC packaging and production process in our company to explain why static electricity is generated. There are mainly the following reasons.
1. The high-resistance materials are used in the production of building decoration materials. The IC production process requires the use of clean workshops or ultra-clean workshops.
It is required that the particle size of the dust particles be changed from the conventional 0.3 μm to 0.1 μm, and the dust density is about 353 particles/m 3 . For this reason, in addition to installing various vacuum cleaners, inorganic and organic non-dusting materials should also be used to prevent dusting. However, the electrical properties of building materials are not considered as an indicator. There are also no provisions in the design specifications of industrial plants for clean workshops. The interior decoration materials mainly used in IC factory cleanrooms include: polyurethane elastic floor, nylon, hard plastic, polyethylene, plastic wallpaper, resin, wood, white porcelain, enamel, gypsum, and so on. Most of the above materials are high molecular compounds or insulators. For example, the organic glass has a bulk resistivity of 1012 to 1014 Ω/cm and the polyethylene has a resistivity of 1013 to 1015 Ω/cm. Therefore, the conductive properties are relatively poor, and static electricity is not easily leaked through the earth to the earth due to a certain cause, thereby causing static electricity to accumulate.
2. Static electricity
The different actions of clean plant operators move back and forth. The soles and the ground are continuously in close contact with each other. The various parts of the human body also have activities and friction. Either brisk walking or slow walking, the trot will generate static electricity, that is, the so-called walking electrification; standing after the human activities. When the work clothes worn by the human body are in contact with the chair surface and separated, static electricity may also be generated. If the body's electrostatic voltage does not go away and it touches the IC chip, it may unknowingly cause the IC to break down.
3, static electricity caused by air conditioning and air purification
Since IC production is required to be performed under 45-55% RH, air conditioning is performed while air purification is performed. The dehumidified air is sent to the clean room via primary filter, intermediate filter, high-efficiency filter and air duct. The general wind speed of the air duct is 8~10m/s. The inner wall of the air duct is painted. When the dry air and air duct, the dry air and the filter move relative to each other, static electricity will be generated. It should be noted that static electricity and humidity have a more sensitive relationship.
In addition, static electricity is generated during the transport of semi-finished products and IC products during packaging and transportation. This is one of the factors that cause electrostatic charging.
Second, the harm of static electricity to IC is quite large. In general, static electricity has the characteristics of high electric potential and strong electric field. In the process of electrostatic charge-discharge, transient high-current discharge and electromagnetic pulse (EMP) are sometimes formed, resulting in a very wide spectrum of electromagnetic radiation field.
In addition, compared with conventional electric energy, the electrostatic energy is relatively small. In the natural electrification-discharge process, the electrostatic discharge (ESD) parameter is uncontrollable and is a difficult random process, so its function is often caused by people. Ignored. Especially in the field of microelectronics technology, the harm it has caused to us is astonishing. According to reports, the direct economic losses caused by static electricity are as high as several hundred million yuan each year. Electrostatic hazards have become a major obstacle to the development of the microelectronics industry.
In the semiconductor device manufacturing plant, the yield of ICs, especially VLSI, is greatly reduced due to the adsorption of dust on the chips. IC production plant operators wear clean work clothes. If the human body is electrostatically charged, dust and dirt are easily adsorbed. If these dust and dirt are brought to the operation site, the quality of the product will be affected, and the performance of the product will be deteriorated. Ic will be greatly reduced. Yield. If the radius of the adsorbed dust particles is larger than 100 μm and the line width is about 100 μm, the film thickness is 50 μm, and the product is most likely to be scrapped.
Again, static electricity damages ICs with certain characteristics.
(1) Concealment Unless electrostatic discharge occurs, the human body cannot directly sense static electricity, but the human body does not necessarily have a feeling of electric shock because of electrostatic discharge. This is because the electrostatic discharge voltage perceived by the human body is 2 to 3 kV, so the static electricity is hidden.
(2) Potentiality The performance of some sinks after being electrostatically damaged does not drop significantly. However, accumulating discharges several times can cause internal damage to IC devices and cause hidden troubles. Therefore, electrostatic damage to the IC is potential.
(3) Random IC Under certain circumstances, it will suffer from electrostatic damage. It can be said that from the time an IC chip is produced until it is damaged, all processes are threatened by static electricity, and the generation of these static electricity is also random. Its damage is also random.
(4) Complexity Failure analysis of electrostatic discharge damage is time-consuming, costly, and expensive because of the fine, detailed, and minute structural features of microelectronic IC products. It requires high technology and often requires the use of highly sophisticated instruments. Even so Some electrostatic damage phenomena are difficult to distinguish from damage caused by other causes; mistakes caused by electrostatic discharge damage are regarded as other failures. This is often attributed to early failure or unclear circumstances before electrostatic discharge damage is fully understood. The failure, and thus unconsciously masked the real cause of the failure. Therefore, it is complicated to analyze the damage of static electricity to the IC.
All in all, it is necessary to establish an electrostatic protection system during the process of IC manufacturing and packaging. IC packaging production lines are more strict with static electricity requirements. In order to ensure the normal operation of the production line, the anti-static building materials are completely renovated in their clean workshops, and all personnel working in and out of clean workshops are equipped with anti-static clothing and other hardware measures. The packaging companies can comply with relevant national standards and the actual conditions of the company. The company formulated the corporate standards or specific requirements for anti-static electricity to meet the normal operation of the IC packaging production line. With the expansion of China's IC packaging line, the increase in packaging capacity year by year, the increase in the number of packages, and the higher requirements for product quality and yield, correspondingly various software and hardware requirements and the awareness of electrostatic protection for all employees Strengthening is even more important, and it is also playing and serving as the "main role" and "invisible killer" that affect the quality of our products. Therefore, electrostatic protection will be a major issue for the entire IC industry now and in the future.
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