The harm of static electricity in clean room
Semiconductors, flat panel displays, optoelectronics and other clean rooms, despite a lot of work, the electrostatic problems in the clean room still affect production safety and product yield, affecting manufacturing costs and benefits, affecting product quality and reliability.
1. Electrostatic Coulomb force
Under the action of electrostatic Coulomb force, the adsorbed dust and dirt cause components to leak or form a short circuit, which impairs performance and greatly reduces the yield and reliability. If the particle size of the dust is >100 μm, the width of the aluminum wire is about 100 μm, and the thickness of the oxide film is 50 μm, the product is most likely to be scrapped. Now the wire diameter is finer, the oxide film is very thin, and the dust particles with small particle size will damage the components. This happens mostly in the processes of corrosion cleaning, photolithography, spot welding and packaging.
2, electrostatic discharge ESD
(1) The insulating oxide film of the component is broken, and the lead is blown or the line is blown. If the human body carries 10KV (100PF) of static charge, ESD occurs when the device is touched, and the pulse discharge current peaks up to 20A (10~100s) can be formed instantaneously to the earth, not to mention high density, fine wire diameter, thin SiO2 film. Lsi, Vlsi, is the general IC, MOS will suffer damage.
Generally speaking, the withstand voltage field strength of the device insulating gate SiO2 film is E=(5-10)×106V/cm. If the film thickness of the device SiO2 is 1000, the static voltage of 50V-100V or more will be hit when the device input pin is applied. Wearing, and the body with static electricity more than 50V, 100V is very common.
(2) causing noise and emitting electromagnetic interference
ESD causes EMI to have a sharp peak before and after the electromagnetic wave, and the signal is strong, which is equivalent to a few volts of energy in the circuit. The frequency spans a few MH2 or hundreds of MH2 of strong noise, which may cause component damage, equipment and sensors do not work properly, or even cause The device crashed.
The EMI caused by ESD also causes an input of an error signal or a latching phenomenon. In a clean room, the EMIF box of the wafer is placed on a steel trolley, and the ESD of the wafer is transmitted to the trolley through the inductor. The wheel is insulated, and the diffusion of EMI causes the wafer handler to crash.
(3) Electric shock to the human body
When the human body's ESD or the human body's ESD exceeds the human body's electric shock limit current of 5 mA or more, people will have various feelings of injury, causing staff's emotional anxiety and operational errors.
Cleanrooms such as semiconductors, flat panel displays, and optoelectronics have done a lot of work, but the static problems in cleanrooms still affect production safety and product yield, affecting manufacturing costs and benefits, and affecting product quality and reliability. According to foreign industrial experts, the annual loss of products due to static electricity in the United States averages 8-33%. Some people estimate that the annual damage to the electronics industry in the United States is worth 10 billion US dollars. In the 1980s, Japan analyzed the scrapped electronic products. The loss caused by ESD accounts for 1/3. China's semiconductors, flat-panel liquid crystal displays, optoelectronics, etc. all started late, but electrostatic hazards also occur from time to time, and the yield is low. Banks, securities companies, confidential databases, monitoring centers, power dispatching rooms, etc., if ESD occurs, it is easy to cause interference, and the data is lost, the situation is even more serious.