US 6,275,742 B1Granted

Wafer aligner system

AssigneeBerkeley Process Control, Inc.

InventorsPaul Sagues, Stephen A. Gaudio, Tim K. Wong

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Abstract

An alignment device for use with a robot for manipulating and aligning a series of semiconductor wafers with respect to an edge fiducial and the center of each wafer is disclosed. The device includes a rotary vacuum chuck for holding a wafer, and an edge detector comprising a light source that extends across the wafer edge as it moves and creates a shadow that falls on a charge coupled device (CCD) below. Output data from the CCD relative to the wafer edge position is processed by a programmable logic circuit and converted to quadrature data which is fed to the logic section of a controller. The controller is programmed to calculate the location of the wafer fiducial relative to the chuck axis and further to calculate the angular and distance offset of the wafer center from the longitudinal axis of the robot arm so that the robot arm can be moved to center the wafer with its fiducial at a preselected location before the wafer is removed from the rotary chuck.

Claims11

Dependent claims

In a system for manipulating a series of disk like elements so that each element can be transported separately by a robot having an articulated two leg arm and an end effector to a station in a precise, predetermined orientation and alignment with respect to a reference fiducial on the element edge and the geometric center of the element, said system comprising:

(a) a machine controller;
(b) a rotary vacuum chuck for supporting an element and having a motor for driving said chuck connected to said controller;
(c) an alignment device including an elongated light source which is above and extends across the outer edge of said element held on said chuck so as to produce a shadow image of an edge of said element;
(d) an elongated sensor means located below said light source and the outer edge of said element and positioned to receive said shadow image;
(e) means for processing the output from said sensor means to produce quadrature signal data relative to the actual position of the edge of said element;
(f) means in said controller for synchronizing quadrature signals from said chuck motor and said sensor means for determining the location of said fiducial on said element and its geometric center relative to said chuck;
and
(g) optical means between said light source and said sensor means for optimizing the demarcation between light and shadow on said sensor means, wherein said optical means comprises first and second pairs of plano-convex lens which are spaced apart between said light source and said sensor means.

5 more elements

Dependencies are inferred from the claim text.