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Mechanism for Reading Hole Pattern Codes

IP.com Disclosure Number: IPCOM000101128D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 4 page(s) / 181K

Publishing Venue

IBM

Related People

Barenboim, M: AUTHOR [+3]

Abstract

This article describes a mechanism for reading the hole identifying each of a number of cassettes held in a row. Such cassettes, which are used to hold disk-shaped silicon wafers and to transport them among various steps in the manufacturing of integrated circuit modules, include flanges with patterns of holes in specific locations, to be used for purposes of identification.

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This is the abbreviated version, containing approximately 37% of the total text.

Mechanism for Reading Hole Pattern Codes

       This article describes a mechanism for reading the hole
identifying each of a number of cassettes held in a row. Such
cassettes, which are used to hold disk-shaped silicon wafers and to
transport them among various steps in the manufacturing of integrated
circuit modules, include flanges with patterns of holes in specific
locations, to be used for purposes of identification.

      This mechanism is intended to be used, for example, with a
device wherein a row of cassettes is held so that the centers of the
essentially circular peripheries of any wafers stored therein are
essentially coaxial, and so that the flanges in which the identifying
hole patterns are located are also in alignment.  When the cassettes
are held in this way, the mechanism described herein can be used to
read all of the hole codes in the row of cassettes, with a single
motion in the direction of the length of these flanges.  The
mechanism for reading such hole codes is attached to the wafer
transfer drive, so that an additional drive mechanism along the row
of cassettes, with associated feedback means, is not required. During
wafer sorting and transfer operations, the mechanism for reading hole
codes is latched in an inoperable position. Overtravel motions of the
attached wafer transfer drive are used to unlatch this mechanism
before it is used, and to relatch it before wafer sorting and
transfer operations are begun.

      This mechanism can furthermore be used with a device which
provides means for a number of such rows of cassettes to be held and
rotated into a position in which wafer sorting and transfer
operations occur.  In such an application, the disclosed mechanism
for reading hole codes is applied to a row of cassettes after it is
moved into this position.  Overtravel motion of the attached wafer
transfer drive is used to move this mechanism out of the way so that
a new row of cassettes can be rotated into this position. Using the
mechanism described herein employs only four pairs of sensors,
arranged to read the hole pattern in a single cassette at a time, and
a drive means, already present in the device for which this mechanism
is intended, is used to move this mechanism out of the way of the
rotation of cassette tables to provide buffering.

      Fig. 1 is a side view of the mechanism and of a cassette having
the pattern of holes to be read.  Fig. 2 is a partial front view of
the mechanism and of this cassette. Referring to Figs. 1 and 2, a
cassette 1, for storing and transporting wafers 2, is clamped in a
specific position relative to a cassette table 3 by clamping means
(not shown).  This cassette 1 includes hole patterns 4 in specific
locations in each of its lower flanges 5, which can be used to
identify the cassette by determining the presence or absence of
holes.  A reader bracket 10 includes a light source 11 and a sensor
12 for each row of holes in hole patterns 4, arranged so...