Massachusetts llstitUte ofTechnologyAhi 帥 stiffrotary 帥 1 魄 machine fer 450rrmi Si wafer has been desigried and developed . in order to impreve a stiflhess of 止 e mach 血 e , rotary and aXial feed motion was built 血 a 帥 d血 g sp 血dle。 As 止 e res 皿 t , we can reduce the number of comp 。 nent parts and successfully developed high stifihess grinding machine . Ke 脚 rd :450
Si wafer diameter tends to be increased from 300 mm to 450 mm in order to increase semiconductor device productivity. To this end, the authors developed a rotary grinding machine with high stiffness, equipped with water hydrostatic bearings. This grinding spindle is designed to govern infeed motion of the grinding wheel. This study investigates the basic design and performance of the grinding spindle system. This system itself is composed of a constant pressure water hydrostatic bearing as a radial bearing and a magnetic actuator as a thrust bearing. The magnetic actuator combine the infeed device and the thrust bearing. The measured results show that the static stiffness, Ks, is 1.06 kN/μm, the natural frequency is 353 Hz, and the positioning accuracy is 0.2 μm. These results meet the performance requirements necessary to grind φ450 mm Si wafer.
Increasing the wafer diameter from φ300 mm to φ450 mm is required to enhance semiconductor devices productivity. A high-stiffness rotary grinding machine equipped with water hydrostatic bearings was developed for a φ450 mm silicon wafer. The grinding machine has an upper structure consisting of a wheel spindle system and a lower structure consisting of a rotary worktable system. The spindle shaft creates both rotary and axial feeding motion. The upper and lower structures are clamped together rigidly by three kinematic couplings. A higher loop stiffness is required for the grinding machine because grinding the larger wafer requires a higher grinding force. This paper investigates the loop stiffness of the developed wafer grinding machine.
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