Electrostatic protection in semiconductor production
In the semiconductor manufacturing process, the prevention and control of static electricity is necessary. If the prevention and control of static electricity is not carried out, problems such as particle pollution, semiconductor damage due to static discharge and related equipment shutdown will occur. The static electricity prevention and control programs in the semiconductor production process include: grounding, static dissipative materials and air ionization neutralization ions. In order to meet the requirements brought about by the rapid development of the semiconductor industry, static dissipative materials and air ionizers are also constantly changing.
The necessity of static control in semiconductor production
In the field of semiconductor production, it is impossible to completely eliminate the negative effects of static electricity. Even with static protection, it is difficult to maintain a high level of product quality and yield. However, if there is a lack of static control, particle pollution, electrostatic discharge damage and equipment failure, these problems are in the manufacture of silicon substrates and photomasks, in the clean room of the semiconductor front-end and in the back-end process including assembly, packaging, and final testing and shipping. It may happen at any time, seriously affecting the quality of semiconductor products.
Semiconductor static control method
In the semiconductor manufacturing environment, whether in the front clean room or in the rear test, assembly and packaging, the grounding of conductors and static dissipative materials should be used. Grounding prevents static electricity from being generated on insulated conductors and static dissipative materials. If these materials carry static electricity, they can also take away static electricity. Every conductive material, including personnel, equipment, factory surfaces (floors, walls, ceilings and work surfaces) and products, should have reliable grounding. These ground terminals should be checked regularly. Some ungrounded conductors are usually static discharge sources.
Static dissipative materials dissipate static charges while maintaining the properties of certain insulating materials (such as flexibility and chemical resistance). If they are reliably grounded, they will not retain static charge. In certain applications (such as desktop computers or test sockets), these materials can replace conductor materials. In these applications, they may come into contact with electrostatically charged products. The high resistance of static dissipative materials (typically in the range of 10^4 to 10^11 ohms) can slow down the charge movement process to prevent electrostatic discharge damage events. Static dissipative materials must be inspected and tested regularly. Many of these materials are not compatible with clean rooms, and static dissipative characteristics will change over time, so they must be selected correctly when using them.
Air ionization is used to neutralize static charges on insulators (and insulated conductors). The principle is that an ionizer (ion fan) generates an ion cloud composed of positive and negative air ions to neutralize static electricity everywhere in the production environment. In the manufacturing process, air ionization must be used to control the electrostatic field generated by the insulator. For example, many aspects of semiconductor production, such as cleanliness, chemical resistance, and high-temperature processes, rely on insulators. For the semiconductor manufacturing industry where manual operations are rarely used, these insulators are also essential inside the process equipment. The most important thing is that the product itself is an insulator, whether it is a front-end semiconductor chip or the final epoxy packaged device.