C36 Influence of Anisotropy of Silicon Wafer on Shape Measurement Accuracy

Abstract

Deflection due to gravity exerts a great influence on the measurement accuracy of the three-point-support inverting method which can measure the warp and thickness of large flat panels simultaneously. Especially when the panels are made of monocrystalline materials like silicon wafers, the influence of the anisotropy of the elastic modulus on the deflection should be taken into consideration. The deflection due to gravity depends on the crystal orientation relative to the three-point-supports. Thus the deviation of actual crystal orientation from the direction indicated by notch causes a measurement error. Rotation of crystal orientation relative to the three-point-supports can prevent the wafer vibration excited by disturbance vibration because resonance frequency of the wafer can be changed.