Method and system for establishing a common reference point on a semiconductor wafer inspected by two or more scanning mechanisms

摘要

A method and system for establishing a common reference point on a semiconductor wafer inspected by two or more scanning mechanisms. The semiconductor wafer includes a plurality of dies of identical size, each die being generally rectangularly shaped and having four corners. Adjacent dies are separated by a die street, the sum of the width of a die and the width of a die street equaling a die period. The method includes scanning the semiconductor wafer with a first scanning mechanism to establish a first coordinate system for the wafer. The first scanning mechanism determines a point on the wafer to be the center of the wafer which is assigned a first coordinate value relative to the first coordinate system. The location of the common reference point in the first coordinate system is calculated as the die corner which is within half the die period from the first coordinate value, the common reference point being assigned a second coordinate value in the first coordinate system. The semiconductor wafer is then scanned by a second scanning mechanism which establishes a second coordinate system for the wafer. The second coordinate value is located in the second coordinate system. The location of the common reference point in the second coordinate system can be calculated as the die corner which is within half the die period from the second coordinate value in the second coordinate system.