Discover sticky dust particles in FAB
During the manufacturing process of semiconductor components, it's not allowed to have too much dust particles in the air; because the particles in the air, for the certain steps in the fabrication of semiconductors, such as cleaning, carrier transport operations or the processes of coating photoresist, will affect the quality of the product and make a significant loss. It is a necessary to perform the work in a cleanroom.
However, there is still a very small amount of dust in the cleanroom. These dusts, apart from air convection, may be from consumables (such as gloves and masks) or produced by the human body. (e.g. the dead skin cells from the surface of the skin).
In the cleanroom, some areas absent of airflow (dead spot) will slowly accumulate micro dust. If the air is disturbed, these airborne micro dusts will fall directly onto the product or staff body and not to be sensed by Particle Counter. These dust particles that are not apt to stay afloat in air within the cleanrooms. When they are gathered together due to static electricity or polarity, it's difficult to blow the sticky dust to the exhaust.
For such sticky dusts, not only the collection efficiency of air filter is low, but also the particle counter is difficult to sense, and once the sticky dusts adhered to an important surface (such as a reticle), it may affect the yield. (The thinner the path, the greater the impact.)
If it's hard for the operator to distinguish dust particles from the background under the general white lighting, that's impossible to clean the dust effectively, and it will result the loss. Therefore, in a cleanroom, if a detection tool with specific wavelength or low-angle collimated light source can be used, the sticky dust on the product will be effectively examined, thereby reducing the defect rate.
Lumos Technology Has Solutions to See These Dust Particles
- Blue excitation light for organic dust particles that emit fluorescence.
- Green light for other dust particles.
- Yellow or 4000k white light for dust particles on mask with pellicle.