Patent ID: 7961309
Filing Date: 2011-06-14
Classification: G03F

Abstract:
1. A metrology tool arranged to measure a parameter of a substrate, provided with a pattern, in a lithographic apparatus, the metrology tool comprising: a base frame; a substrate table constructed and arranged to hold the substrate; at least one sensor constructed and arranged to measure a parameter of the substrate; a displacement system constructed and arranged to displace one of the substrate table and sensor with respect to the other one in at least a first and second direction, the second direction being perpendicular and in the same plane as the first direction; a first and second balance mass; a first bearing configured to movably support the first balance mass so as to be substantially free to translate in a direction opposite of the first direction; a second bearing configured to movably support the second balance mass so as to be substantially free to translate in an opposite direction of the second direction; a first balance mass positioning actuator connected to the first balance mass and constructed and arranged to counteract a displacement of the one of the substrate table and sensor in the first direction; and a second balance mass positioning actuator connected to the second balance mass and constructed and arranged to counteract a displacement of the one of the substrate table and sensor in the second direction, whereby the position of a combined center of gravity of the first and second balance mass and the one of the substrate table and sensor relative to the base frame remains substantially stationary.