Development of a Rotary Fast Tool Servo for Ultraprecision Grinding of Silicon Wafer

摘要

Ultraprecision ductile-mode grinding has been expected as new manufacturing technology on silicon wafer shaping process. In order to achieve ductile-mode grinding, it is necessary to ensure that the depth of cut made by an individual abrasive grain does not exceed the critical depth-of-cut; therefore a grinding machine with high motion accuracy and high stiffness is needed to control the depth of cut. The linear guiding system of such grinding machine is required to have accuracy on the order of nanometers , because the motion accuracy of the linear guiding system infeeding a grinding spindle unit has the major influence on the depth of cut. However, it is difficult to accomplish nanometer-feeding with the conventional linear guiding system. Our work aims to reduce the subsurface damage of silicon wafer by achieving nanometer-feeding of the linear guiding system. For this purpose, we have developed a rotary fast tool servo (RFTS) which compensates the motion error of the slide table infeeding the grinding spindle unit. Consequently it was clarified that the subsurface damage of silicon wafer was reduced by using the RFTS.