Exposure field sensor of a chip leveling apparatus having an aperture for changing at least one dimension of the incident light of the sensor

摘要

A chip leveling apparatus of wafer exposure equipment adjusts the diameter of the light incident on a wafer according to the chip size so that the inclination of that area can be accurately detected for use in leveling the wafer in preparation for exposure. A wafer leveling stage supports the wafer during its exposure. A stage driving mechanism can adjust the inclination of the wafer leveling stage relative to the horizontal. A light source produces a collimated beam of light which is directed towards the wafer exposure field at an acute angle. A location sensor is fixed in position to receive the light once the light has reflected from the exposure field, and thereby senses the inclination of the exposure field. A computer controller receives information from the sensor and controls the stage driving mechanism accordingly. To ensure that the information generated by the location sensor is an accurate representation of the inclination of the exposure field, an iris having an aperture matched to the exposure field is provided in the path of the light before it meets the wafer, whereby the spot of light incident on the wafer coincides best with the exposure field.