US 6,256,555 B1 · Robot arm with specimen edge gripping end effector

Abstract

Robot arm (16) end effectors (10, 110) of this invention rapidly and cleanly transfer between a wafer cassette (14) and a processing station semiconductor wafers (12) having diameters greater than 150 mm. The end effectors include proximal and distal rest pads (24, 26, 124,126) having pad and backstop portions (32, 34, 132, 134) that support and grip the wafer within an annular exclusion zone (30) that extends inward from a peripheral edge (30) of the wafer. An active contact point (50, 150) is movable by a vacuum actuated piston (52, 152) between a retracted wafer-loading position and an extended position that urges the wafer against the distal rest pads to grip the wafer within the exclusion zone. The end effector further includes fiber optic light transmission sensors (90, 102, 202) for locating the wafer periphery and bottom surface (100, 200). The sensors provide robot arm extension and elevation positioning data supporting methods of rapidly and accurately placing and retrieving a wafer from among a stack of closely spaced apart wafers stored in the wafer cassette. The methods effectively prevent accidental contact between the end effector and the wafers while effecting clean, but secure, gripping of the wafer at its edge or within its exclusion zone.

Claims19

Dependent claims

A robotic arm end effector apparatus for gripping a specimen by its peripheral edge, comprising:

a body having a proximal end attached to the robotic arm and an opposed distal end;
at least one distal rest pad attached to the distal end of the body and having a pad portion for supporting the peripheral edge of the specimen and a backstop portion that forms with the pad portion an included angle for gripping the peripheral edge of the specimen;
at least one proximal rest pad coupled to the proximal end of the body for supporting the peripheral edge of the specimen;
and
a proximal end active contact point movable between a retracted specimen-loading position and an extended specimen-gripping position in which the peripheral edge of the specimen is urged into the included angle formed in the distal rest pad.

2 more elements

A method for retrieving from a wafer cassette a semiconductor wafer having a periphery, comprising:

providing a robotic arm with an end effector having a proximal end and an opposed distal end, the end effector movable in X and Z directions and further including at least one distal rest pad having a pad portion for supporting the edge of the wafer and a backstop portion that forms with the pad portion an included angle for gripping the edge of the wafer, and a proximal end active contact point movable between a retracted and extended positions;
retracting the active contact point;
moving the end effector an X direction distance into the cassette;
elevating the end effector in the Z direction to contact the edge of the wafer on the pad portion of the landing pad;
extending the active contact point to urge the edge of the wafer into the included angle between the pad and backstop portions of the distal rest pad, thereby gripping the wafer;
and
retrieving the wafer in the X direction from the cassette.

4 more elements

Dependencies are inferred from the claim text.

Robot arm with specimen edge gripping end effector

Life of this patent

Robot arm with specimen edge gripping end effector

Life of this patent

Abstract

Claims19