Development of rotary table grinding machine for large diameter Si wafers (1^st report: Performance investigation of water hydrostatic rotary table)

Abstract

Increasing of Si wafer diameter from φ300 mm to φ450 mm is required to enhance productivity of semiconductor devices. The authors developed a high stiff rotary grinding machine, which consists of a rotary table system and a wheel spindle system. These system are rigidly clamped using three ball screws and kinematic couplings. This paper investigates a basic design and the performances of the rotary table system equipped with constant flow water hydrostatic bearings. A fluid analysis around bearing pad was attempted by using the finite volume method in order to enhance a static stiffness of water hydrostatic thrust bearing. Performances of the developed rotary table was evaluated experimentally and compared with the analyzed value. The measured static stiffness and the numerical analyzed static stiffness ware 1.96 kN/μm and 1.97 kN/μm, respectively under the flow rate of each bearing pads Q=30 mL/min.