The influence of static factors on IC packaging
With the continuous and steady growth of China's national economy and the continuous innovation and development of production technology, the production process has higher and higher requirements for the production environment. The processes in the large-scale and ultra-large-scale Ic production put forward higher requirements on the production environment, not only to maintain a certain temperature, humidity, cleanliness, but also to pay sufficient attention to electrostatic protection.
As we all know, the packaging industry belongs to the downstream production process in the whole IC production. In this process, for plastic ICs, hybrid ICs or monolithic ICs, there are mainly wafer thinning (grinding), wafer cutting (dicing), Upper core (adhesive sheet), pressure welding (bonding), encapsulation (encapsulation), pre-curing, electroplating, printing, post-curing, cutting, tube loading, post-sealing testing, etc. Each process has different requirements for different process environments.
The influence of static factors on IC packaging
First, the cause of static electricity is everywhere. Today, with the rapid development of technology and the high degree of automation of 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 affect product quality. Here, combined with the actual situation of our factory in the integrated circuit packaging and production process to explain the reason for the occurrence of static electricity, there are mainly the following reasons.
1. High-resistance materials are used in the construction and decoration materials of the production workshop. The IC production process requires the use of clean workshops or ultra-clean workshops.
It is required that the particle size of the dust-removing particles is changed from the conventional 0.3 μm to 0.1 μm, and the dust particle density is about 353/m3. To this end, in addition to the installation of various vacuuming equipment, inorganic and organic non-dusting materials are also used to prevent dusting. However, the electrical properties of building materials are not taken into account as an indicator. There are also no provisions in the design specifications for industrial plants. The interior decoration materials used in the clean factory of the IC factory are: polyurethane elastic floor, nylon, hard plastic, polyethylene, plastic wallpaper, resin, wood, white porcelain, enamel, plaster and so on. Most of the above materials are polymer compounds or insulators. For example, the vitrinite resistivity is 1012 to 1014 Ω/cm, and the polyethylene resistivity is 1013 to 1015 Ω/cm, so that the electrical conductivity is relatively poor. For some reason, static electricity does not easily leak to the earth through them, thereby causing static electricity to accumulate.
2, the body static
The different actions of the operators of the clean plant and the movements of the back and forth, the sole and the ground are constantly in close contact and separation, and the various parts of the human body also have activities and friction. Whether it is walking fast or slow, the trotting will generate static electricity, which is called walking and charging; Static electricity is also generated when the work clothes worn by the human body are separated from the surface of the chair. If the static voltage of the human body cannot be removed, and the IC chip is touched, the IC may be broken down unconsciously.
3. Static electricity caused by air conditioning and air purification
Since the IC production requirements are carried out under conditions of 45-55% RH, air conditioning is required and air purification is required. The dehumidified air is sent to the clean room through the primary filter, the medium efficiency filter, the high efficiency filter and the air duct. Generally, the total air duct wind speed is 8~10m/s, and the inner wall of the air duct is painted. When the dry air and the air duct, the dry air and the filter move relative to each other, static electricity is generated. It should be noted that static electricity has a relatively sensitive relationship with humidity.
In addition, the transportation of semi-finished products and IC products will generate static electricity during packaging and transportation, which is one of the factors of electrostatic charging.
Second, the harm of static electricity to IC is quite large. In general, static electricity has the characteristics of high potential and strong electric field. In the process of electrostatic electrification-discharge, transient high-current discharge and electromagnetic pulse (EMP) are sometimes formed, resulting in a 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 process that is difficult to repeat, so its role is often used by people. Neglected. Especially in the field of microelectronics, the harm it causes us is amazing. It is reported that the direct economic loss caused by static electricity is as high as several hundred million yuan every year. The electrostatic hazard has become a major obstacle to the development of the microelectronics industry.
In the semiconductor device manufacturing plant, the yield of ICs, especially very large scale integrated circuits (VLSIs), is greatly reduced due to the adsorption of dust on the chips. IC production workshop operators wear clean overalls. If the human body is charged with static electricity, it is easy to absorb dust, dirt, etc. If these dusts and dirt are brought to the operation site, it will affect product quality, deteriorate product performance, and greatly reduce Ic. Yield. If the radius of the adsorbed dust particles is larger than 100 μm and the line width is about 100 μm, when the film thickness is 50 μm, the product is most likely to be scrapped.
Again, static damage to the IC has certain characteristics.
(1) Concealment Unless the electrostatic discharge occurs, the human body cannot directly sense static electricity, but the human body may not have the feeling of electric shock when it is electrostatically discharged. This is because the electrostatic discharge voltage perceived by the human body is 2~3kv, so the static electricity is concealed.
(2) Potentiality There is no significant drop in the performance of some sinks after electrostatic damage, but multiple accumulating discharges can cause internal injuries to IC devices and pose a hidden danger. Therefore, the damage of static electricity to the IC is potential.
(3) Under what circumstances will random ICs suffer electrostatic damage? It can be said that all processes are threatened by static electricity from the time of generation of an IC chip until it is damaged, and the generation of these static electricity is random. Its damage is also random.
(4) The failure analysis of complex electrostatic discharge damage is time-consuming, labor-intensive, and expensive due to the fine, fine, and small structural features of microelectronic IC products. High-tech is required and highly sophisticated instruments are often required. Even so Some electrostatic damage phenomena are also difficult to distinguish from damage caused by other causes; people mistakenly regard the failure of electrostatic discharge damage as other failures, which is often attributed to early failure or unclear situation before the electrostatic discharge damage is not fully recognized. The failure, so unconsciously masked the real cause of failure. Therefore, it is complicated to analyze the damage of static electricity to IC.
All in all, it is necessary to establish an ESD protection system during the processing and packaging of ICs! The IC packaging production line has stricter requirements on static electricity. In order to ensure the normal operation of the production line, the overall decoration of the anti-static building materials for its clean factory, and the hardware measures for all the personnel entering and leaving the clean factory to be equipped with anti-static clothing, the packaging enterprises can be based on the relevant national standards and the actual situation of the enterprise. The company has established enterprise standards or specific requirements for anti-static to meet the normal operation of the IC packaging production line. With the expansion of China's IC packaging line, the increasing packaging capacity, the increase of packaging varieties and the higher requirements for product quality and yield, correspondingly, various software and hardware requirements and awareness of static protection for all employees Strengthening is even more important, and it is playing and acting as the "major role" and "invisible killer" that affects the quality of our products. Therefore, static protection will be a major issue in the entire IC industry now and in the future.