Automated wafer inspection system

A system for transporting and precisely positioning a semiconductor wafer relative to an optical inspection axis without introducing contamination or mechanical instabilities comprising:

• a frame having a pair of spaced apart side support means bounding an interior wafer inspection position within a two-dimensional reference area, the frame further including a horizontal reference surface transverse to and intercepted by the inspection axis and within the side support means, and bridge means spanning the side support means above the reference surface and mounted to each of the support means;
• optical inspection means mounted on the bridge means, the bridge means spanning the reference area and the optical inspection means being positioned on the bridge means along the vertical inspection axis;
• XY stage means mounted on and movable within the limits of the reference surface in two orthogonal directions, and including wafer support means substantially at a first horizontal plane a predetermined distance above the reference surface;
• first wafer storage cassette means disposed adjacent the first of the side support means and including means for positioning any of a plurality of stacked wafer storage cells substantially at the first horizontal plane;
• second wafer storage cassette means disposed adjacent the second of the side support means and including means for positioning any of a plurality of stacked wafer storage cells substantially at the first horizontal plane;
• and
• wafer transport means including wafer holding means disposed substantially at the first horizontal plane a movable laterally along one side of the frame to transfer wafers between the first and second cassette means and the inspection position, the wafer transport means further comprising a laterally positioned cylinder, an internal piston therein, and trolley means coupled to the piston and the wafer holding means and movable with the piston.

A system for transporting and precisely positioning a semiconductor wafer relative to an optical inspection axis without introducing contamination or mechanical instabilities comprising:

• a frame having a pair of spaced part side support means bounding an interior wafer inspection position within a two-dimensional reference area, the frame further including a horizontal reference surface transverse to and intercepted by the inspection axis and within the side support means, and bridge means spanning the side support means above the reference surface and mounted to each of the side support means;
• optical inspection means mounted on the bridge means, the bridge means spanning the reference area and the optical inspection means being positioned on the bridge means along the vertical inspection axis;
• XY stage means mounted on and movable within the limits of the reference surface in two orthogonal directions, and including wafer support means substantially at a first horizontal plane a predetermined distance above the reference surface;
• first wafer storage cassette means disposed adjacent the first of the side support means and including means for positioning any of a plurality of stacked wafer storage cells substantially at the first horizontal plane;
• second wafer storage cassette means disposed adjacent the second of the side support mans and including means for positioning any of a plurality of stacked wafer storage cells substantially at the first horizontal plane;
• and
• wafer transport means including wafer holding means disposed substantially at the first horizontal plane and movable laterally along one side of the frame to transfer wafers between the first and second cassette means and the inspection position, the wafer transport means further comprising a pair of wafer support probes spaced apart by a distance equal to the distance between the inspection axis and the cassette means, the two cassette means being spaced form the inspection axis by a predetermined and equal distance.

A system for transporting and positioning semiconductor wafers or like precision elements so that individual microregions of individual dies on the wafer can be viewed or automatically inspected along a vertical inspection axis, the system comprising the combination of:

• a pair of wafer cassette means, each mounted on a different;
• side of the optical inspection axis along an X axis direction,
• wafer transport means positioned along one boundary of the system and movable along a first horizontal plane in the X axis and Y axis and Y axis directions, and including means for simultaneously engaging the underside of a wafer disposed in either cassette means and a wafer positioned along the inspection axis;
• control means for positioning the wafer cassette means at different vertical positions relative to the first horizontal plane, so as to enable transfer of selected wafers on the cassette means to and from the wafer transport means;
• wafer positioning means mounted adjacent the wafer transport means and movable in two orthogonal directions in a second horizontal plane encompassing the inspection axis;
• as rotatable chuck mounted on the wafer positioning means having an uppermost wafer support surface substantially at the first horizontal plane and including means for moving the support surface vertically in an incremental motion;
• and
• control means for introducing delta motions in the wafer cassette means and the vertical chuck in conjunction with the wafer transport means to effect engagement and release of selected wafers.

A system for transporting semiconductor wafers securely but without contamination between first and second positions separated apart in a given plane comprising:

• a controllable pneumatic piston mechanism lying parallel to the given plane and along a second axis parallel to but spaced apart from a first axis defined by the first and second positions, the piston mechanism including a piston movable along the axis of the piston mechanism;
• means mounted adjacent the first axis for supporting the piston mechanism, the supporting means being controllably positionable in a direction normal to the first axis;
• trolley means projecting from the piston of the piston mechanism and movable therewith parallel to the second axis and generally along the given plane;
• and
• vacuum probe means coupled to the trolley means and extending therefrom in a direction normal to the first axis and toward the first and second positions to engage or release wafers thereat.

A system for transporting and precisely positioning semiconductor wafers relative to an optical inspection axis and for inspecting the wafers, the system comprising:

• a frame;
• optical inspection means mounted on the frame along the inspection axis;
• a wafer support positioned along the inspection axis within the frame adjacent the optical inspection means, the wafer support having an upper wafer-supporting surface lying substantially along a horizontal plane extending substantially perpendicular to the inspection axis;
• a first wafer storage cassette disposed on one side of the frame and including means for positioning any of a plurality of stacked wafer storage cells substantially at the horizontal plane;
• a second wafer storage cassette disposed on the other side of the frame and including means for positioning any of a plurality of stacked wafer storage cells substantially at the horizontal plane, the first and second wafer storage cassettes and said wafer support being substantially in alignment, the inspection axis being disposed between and equidistant from the first and second wafer storage cassettes;
• and
• a wafer transport means comprising a pair of parallel wafer support probes extending toward the cassettes and wafer support and movable in unison substantially along the horizontal plane, the probes being spaced apart by a distance equal to the distance between the inspection axis and each of the wafer storage cassettes, one of the probes being adapted to transport wafers between the first wafer storage cassette and the wafer support, and the other of the probes being adapted to transport wafers between the second wafer storage cassette and the wafer support.

A system for inspecting semiconductor wafers relative to an optical inspection axis, the system comprising:

• a frame having a pair loft spaced apart side supports, means within the confines of the frame and spanning the side supports for defining a horizontal reference surface intercepted by the inspection axis, and a bridge spanning the upper extremities of the side supports above the horizontal reference surface;
• optical inspection means mounted on the bridge along the inspection axis;
• an XY stage mounted within the frame on the horizontal reference surface and movable parallel to the horizontal reference surface in two orthogonal directions;
• a wafer support carried by the XY stage within the confines of the frame for positioning relative to the inspection axis, the wafer support defining a wafer-supporting surface lying substantially along a horizontal plane above and parallel to the horizontal reference surface;
• the frame side supports, bridge and reference surface-defining means providing a stable, vibration-free mount for the optical inspection means and wafer support;
• a first wafer storage cassette disposed outside the frame adjacent one of the side supports, the first cassette including a plurality of stacked wafer storage cells and means for positioning any of the cells substantially at the horizontal plane;
• a second wafer storage cassette disposed outside the frame adjacent the other side support, the second cassette including a plurality of stacked wafer storage cells and means for positioning any of the cells substantially at the horizontally plane;
• the wafer storage cassettes and the inspection axis being in substantial alignment in the direction of a first axis orthogonal to the inspection axis, the cassettes being symmetrically disposed relative to the inspection axis, each cassette being spaced apart from the inspection axis by a predetermined distance;
• a wafer transport apparatus outside of the frame and including a pair of parallel wafer support probes extending toward the wafer cassettes and wafer support in a direction parallel to a second axis mutually orthogonal to the inspection axis and first axis, the probes being spaced apart by the predetermined distance and movable in unison substantially along the horizontal plane, one of the probes being adapted to transport wafers between the first wafer storage cassette and the wafer support, the other probe being adapted to transport wafers between the second wafer storage cassette and the wafer support;
• a first linear device mechanism coupled to the probes for moving the probes between limit positions in a direction parallel to the first axis, the limit positions being spaced apart by the predetermined distance, at one of the limit positions one of the probes being in alignment with the first wafer cassette and the other probe being in alignment with the wafer support, and at the other limit position the one probe being in alignment with the wafer support and the other probe being in alignment with the second wafer cassette;
• and
• a second linear drive mechanism coupled to the first linear drive mechanism for advancing and retracting the first drive mechanism and probes relative to the cassettes and wafer support in a direction parallel to the second axis.