The extent of precision required for manufacturing and inspection of LSI is less than 1 micron meter, i.e., in the order of 0.1 micron meter. To attain to such a degree of precision, highly strict conditions must be met with. Prior to the building construction, the interior environments including the structural form, temperature, cleanliness of air and vibration must be studied. Though structure, air-conditioning system, floor vibration and power lines, etc. are well studied beforehand, the speed of equipment development is often so fast that the interior conditions of the building happens to lag behind, resulting in the insufficient realization of precision function. Therefore, items of equipment delivered into the building are often laid out in quite a haphazard manner. Such instances are as follows.
Exterior Factor Exterior Factor Exterior Factor
Electromagnetic Noise Electromagnetic Noise
Constant minute vibration of the ground, traffic vibration, air-conditioning equipment vibration and noise in the building, acoustic noise, vibration and noises by machine tools and processing machines.
Direct Current
Ground Magnetism Movement of surrounding stages (steppers, inspecting equipment, etc.), magnetic bodies (elevators, rolling stocks, trolleys, etc.)
Direct Current Power Source Equipment with direct current power source, magnet (electromagnet, permanent magnet) inside.
Railway Trolley Line Trolley line (DC)of JR & private railways
AC Magnetic Field
Equipment power source Electric power lines in the vicinity of equipment including air-conditioning units.
Power Lines Ultra high tension power line of the electric company and high tension power line in the factory compound.
Line noises
Inverter lines, heater, high frequency generator, and discharge equipment.