Fabrication of Non-contact Transportation System by Combination of Ultrasonically Acoustic Viscous Force and Aerostatic Force

Abstract

In recent years, the size of plane substrates and semiconductor wafers has increased. As conventional contact transportation systems composed of, for example, carrier rollers, belt conveyers, and robot hands carry these longer and wider substrates, the increased weight results in increased potential for fracture. A non-contact transportation system is required to solve this problem. We propose a new non-contact transportation system combining acoustic viscous and aerostatic forces to provide damage-free transport. In this system, substrates are supported by aerostatic force and transported by acoustic viscous streaming induced by traveling wave deformation of a disk-type stator. We constructed the experimental equipment using a rotational disk with a 95mm diameter. Electric power was 70W at an input voltage of 200Vpp. A rotational torque of 8.5×10-5 Nm was obtained when clearance between the stator and disk was 120μm. Finally, we constructed a noncontact transport apparatus for polycrystalline silicon wafers (150(W) × 150(L) × 0.3(t)), producing a carrying speed of 59.2 mm/s at a clearance of 0.3mm between the stator and wafer. The carrying force when four stators acted on the wafer was 2×10-3N. Thus, the new noncontact transportation system was demonstrated to be effective.