Patent ID: 7315373
Filing Date: 2008-01-01
Classification: H01L

Abstract:
1. A method of positioning a circular wafer with a wafer positioning device comprising a line sensor capable of generating a sensor line, a wafer seat capable of seating a wafer, a wafer seat driver capable of moving the wafer seat in two-dimensional directions or three-dimensional directions and rotating the wafer seat about a given rotation axis to move a wafer center point to a given position and to orient a wafer notch part in a given direction, and a calculation unit capable of calculating a wafer center point position and a notch part angle based on a rotation of the wafer seat by the wafer seat driver and detection results of an outer periphery edge of the wafer lying on the wafer seat by the line sensor, the method comprising: positioning the wafer seat at an initial reference position, such that the rotation axis of the wafer seat intersects the sensor line of the line sensor, and rotating the wafer seat on which the wafer lies on the rotation axis, by the wafer seat driver; finding α, β geometrically calculating θ, ΔX, and ΔY as measured from the initial reference position, by the calculation unit; and moving the rotation axis in the directions ΔX and ΔY, rotating the wafer seat about the rotation axis by the rotation angle θ, and then stopping the wafer seat, without removing the wafer from the wafer seat, by the wafer seat driver, wherein θ is calculated or approximated as where Lm is a maximum eccentric radius or a minimum eccentric radius of the wafer as measured from an eccentric center of the wafer, defined by an intersection of the rotation axis with the wafer, to the outer periphery edge of the wafer, d is a deviance distance from the wafer center point position to the eccentric center of the wafer, r is a predetermined radius of the wafer, θ is a rotation angle of the wafer seat about the rotation axis, as measured from the initial reference position, to orient the notch part in the given direction, α is a rotation angle of the wafer seat about the rotation axis, as measured from the initial reference position, to a position obtained when the eccentric radius of the wafer firstly becomes the maximum eccentric radius or the minimum eccentric radius, β β γ is an angle, with respect to the initial reference position, formed between the sensor line and a line extending through both the wafer center point and a point bisecting a line between the first end and the final end of the notch part, ΔX is a movement distance of the rotation axis in an X axis direction, and ΔY is a movement distance of the rotation axis in a Y axis direction.