Minute-particle reduction by applying thermophoresis to semiconductor production equipment

As the size of semiconductor chips decreased, the diameter of particles on the silicon wafers to be controlled becomes smaller. These minute-particles are more greatly affected by diffusion than gravity and inertia. We proposed thermophoresis as a new particle control method. The effect of thermophoresis was investigated in a piece of experimental crosswind equipment with transportation of wafers in mind. The adhesion rate of 50 nm particles on 10 K heated wafer could be decreased to 1/20 than reference wafer. Then, in actual semiconductor production equipment, the effect of thermophoresis was investigated. the adhesion rate on 8 K heated wafer decreased to 1/10 than reference wafer. Then, we proposed to expand area of heater for thermophoresis. And we verified them with simulation. Thermophoresis effect of wide area heater was twice larger than conventional heater.