Atmospheric Pre-aligner Manual
4000-0015 Rev 1
1
Overview
A pre-aligner determines the center and orientation of a wafer and re-
orients the wafer. It centers the wafer and aligns the flat or notch to a user-
programmable angle.
A wafer handling system requires a pre-aligner if:
• The wafer notch must be oriented to some axis in the tool.
• The wafer must be placed in the process or measurement tool with
greater precision than the cassette tolerance allows.
• The wafer pattern must be placed in the process or measurement tool
within the field of view of a pattern recognition camera.
Equipe atmospheric pre-aligners combine high resolution optical sensing
with Charged Couple Device (CCD) pixel resolution of 10.7 microns.
High-precision mechanics and chuck-encoder resolution of 0.018° ensure
consistent performance and repeatability. A uniform light source provides
optimal illumination of the CCD sensors.
Pre-aligner Axes
Equipe builds three-axis and single-axis pre-aligners.
A three-axis pre-aligner can independently align a wafer while the robot is
processing another wafer. The chuck spins the wafer between the LED
array and CCD array and the three pins lift and shift the wafer. A Pre-
aligner Amplifier Board in the controller amplifies the PWM motor-driven
signals to drive the three motors in the Pre-aligner. Three servo axes move
in three directions during alignment:
• The vertical axis raises and lowers the wafer using the pins.
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