Cleaning is one of the most important steps in the manufacturing of semiconductors. As the devices grow smaller, their sensitivity to dust, bacteria, and certain gasses increases. Simply blowing air or nitrogen across a surface will remove the larger particles (=5 microns), but these days we are concerned about particles as small as 0.1 micron.

What if we were to combine static electricity with critical cleaning technologies?

Any time air or water blows across a surface, the fluid at the surface will be—except at its outermost edge, where the fluid meets the air—at rest. Because this area, called the boundary layer,1 is some microns thick, any 0.1 to 2 micron particles will be left on the surface. The situation is made somewhat worse by the fact that because the small particles are held to the surface by molecular attraction, it is difficult to remove them. Washing with liquid cleaners or using a technology such as megasonics can certainly help, but in many cases, liquid cleaners or megasonics cannot be used because no fluid can ever really reach the surface. This may be the time for dry ice or CO₂ particle cleaning.