Strasbaugh nTellect (Model 7AF) Wafer Grinder
4 - 8 Version 1.2 - June 2004
The robot arm performs radial movements via a specially constructed belt driven
pulley system. In addition to the pulley system, the arm consists of two supporting
rings, a limit ring, a virtual arm, a forearm, and an end effector base with dowel pins.
The end effector base is part of the external timing pulley of the forearm.
The cover, made from a single piece of black anodized aluminum sheet metal and
tightly closed on the robot's body with two plastic latches, protects the robot's
mechanism and seals the robot's body. The sealing of the body permits vacuum
evacuation of the robot and its arm when a vacuum exhaust hose is attached to the
flange on the bottom of the robot.
PRE-ALIGNER
The Equipe Technologies pre-aligner centers the wafer and aligns the notch or flat
(usually notch for eight-inch wafers and flat for six-inch wafers) using optical sensing
and a closed loop servo driven three-axis mechanism. During alignment the wafer can
be raised and lowered, moved radially, and rotated around a center axis. The
mechanism first rotates the incoming wafer over a linear array CCD sensor. The CCD
sensor, with an associated uniform light source, provides data to the separate
controller box and its internal computer over a parallel I/O link. The controller box
computer then analyses the data and computes a vector of offset for the wafer to place
the wafer in a position concentric to the chuck.
The pre-aligner is equipped with vacuum pins around the rotating chuck which move
up and down to lift the wafer in an "x" direction to shift the wafer's center position.
The vector of offset is aligned with the directional movement of the pins which move
up to perform the offset.
The pre-aligner then moves the primary flat or notch back over the sensor for a high
resolution scan after which the center of the flat or notch is moved to the user
specified position. The pre-aligner signals when alignment is complete and the wafer
is ready to be picked up by the robot.
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