Abstract: A method and apparatus for a charged particle scanning system and an automatic inspection system, including wafers and masks used in microcircuit fabrication. A charged particle beam is directed at the surface of a substrate for scanning that substrate and a selection of detectors are included to detect at least one of the secondary charged particles, back-scattered charged particles and transmitted charged particles from the substrate. The substrate is mounted on an x-y stage to provide at least one degree of freedom while the substrate is being scanned by the charged particle beam. The substrate is also subjected to an electric field on it's surface to accelerate the secondary charged particles. The system facilitates inspection at low beam energies on charge sensitive insulating substrates and has the capability to accurately measure the position of the substrate with respect to the charged particle beam.

Abstract: In an automatic wafer inspection system, the objective lenses used in micro inspection are mounted on a turret which is attached to an adjustable turret support member. Several lenses may be brought sequentially into position for inspection of the patterned wafer and it is necessary that the handoff be precise so as to maintain the same pattern in the viewing position. V-slots are mounted on the turret in such a location as to be correctly associated with the precise position for each lens. A detent ball spring is biased to drive into a V-slot so as to hold the associated lens in the precise viewing position. When hand-off to the next lens is to be accomplished, a counter force is applied which overcomes the spring bias and pulls the detent ball out of the V-slot. A drive motor is then enabled, which turns the turret a predetermined distance to bring the wide opening of the next adjacent V-slot into approximate alignment with the detent ball and the drive motor is disabled.

Abstract: An object mounting member is slideably interconnected with a guide member which provides a path between two separated fixed locations. The guide member is attached to a support member having fixed stops located between the two fixed locations. A pinion gear is fixedly attached to the shaft of a stepper motor, and a spur gear is held in an engaging relationship with said pinion gear. An eccentric arm is pivotally attached at one end to the spur gear and is driven to provide rapid motion between the two fixed locations with a rate of motion approaching zero hit nears each fixed location. The other end of the eccentric arm is pivotally attached to one end of a drive arm that is pivotally attached to the object mounting member. The drive arm includes a spring loaded member that is used to allow the object mounting member to be preloaded against a stop at each end of its travel.