Browse Prior Art Database

Buffer Mechanism for Wafer Sorting And Transfer Device

IP.com Disclosure Number: IPCOM000101184D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 4 page(s) / 180K

Publishing Venue

IBM

Related People

Barenboim, M: AUTHOR [+3]

Abstract

This article describes a buffer mechanism for use with a wafer transfer tool to provide an additional supply of items to be processed and of locations into which processed items may be placed.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 41% of the total text.

Buffer Mechanism for Wafer Sorting And Transfer Device

       This article describes a buffer mechanism for use with a
wafer transfer tool to provide an additional supply of items to be
processed and of locations into which processed items may be placed.

      The objective of the mechanism described herein is to provide a
buffer consisting of additional wafer cassettes which can be loaded
into the transfer device to act as sources of wafers and as
destination slots.  It can operate, for example, with four cassette
tables, each of which holds six cassettes.  Thus, while only one of
these tables with up to six cassettes is used for wafer sorting and
transfer operations at a time, the remaining three cassette tables
with up to eighteen additional cassettes are used to provide a
buffer.

      Fig. 1 is a side view of the buffer mechanism described herein.
Fig. 2 is a partial front view showing the left and right ends of
this mechanism.  Referring to Fig. 1 wafer transport mechanism 10 is
configured to pick up a wafer 11 from a slot in a cassette 12, to
move the wafer into an upper position at 13, to rotate the wafer
about a drive axis 14, and to read a bar code (not shown) present on
the side of the wafer, thereby determining the appropriate slot for
the wafer to be placed among the various slots available in cassettes
12.  The wafer 11 in its upper position 13 is then moved to this
appropriate slot and inserted therein by wafer transport mechanism
10.

      Wafer transport operations of this kind occur among the slots
in a number of cassettes 12, which are arranged so that the axes of
the wafers 11 held therein are essentially coaxial.

      Referring to Figs. 1 and 2 in the application of the mechanism
described herein, each cassette 12 is clamped to a cassette table 15,
each of which is, in turn, pivotably mounted to a right end drive
crank 16 by means of a right end pin 17 and to a left end
drive crank 18 by means of left end pin 19.  The right and left end
drive cranks 16 and 18 are securely mounted on short crank shafts 20,
which in turn rotate in bearings 21 attached to stationary machine
frame plates 22.  Each of these crank shafts 20 is rotationally
driven from drive shaft 23 by means of drive pulley 24 and driven
pulley 25, both of which engage a toothed belt 26. Drive shaft 23 is,
in turn, driven by a drive motor assembly 27, under operator or
program control, by means of drive pulley 28 and driven pulley 29,
both of which engage toothed belt 30.  Thus, the right and left end
drive cranks 16 and 18 are constrained to rotate through equal
angles, and the four cassette tables 15 are, in turn, constrained to
remain horizontal as these cranks are rotated.

      As a practical matter, pivot pins at diagonal corners of the
cassette tables 15 would, due to the clearances required to allow
relative motion, not constrain the tables to be held horizontally.
For this reason, the mechanism is configured so th...