U.S. patent application number 09/975663 was filed with the patent office on 2003-04-10 for anti-esd movable rack system for storing reticles.
This patent application is currently assigned to Taiwan Semiconductor Manufacturing Co., Ltd.. Invention is credited to Kuo, Kun-Tsang.
Application Number | 20030067253 09/975663 |
Document ID | / |
Family ID | 29216606 |
Filed Date | 2003-04-10 |
United States Patent
Application |
20030067253 |
Kind Code |
A1 |
Kuo, Kun-Tsang |
April 10, 2003 |
Anti-ESD movable rack system for storing reticles
Abstract
A reticle storing movable rack system comprises a plurality of
flat tracks fixedly secured to a floor. There is provided a
plurality of rows of storage units. Each row has a plurality of
independent racks interconnected with each other, which racks are
adapted to be moved as a single row along the flat tracks. A user
engageable drive assist mechanism is provided to move the rows.
Each of the racks comprises shelves with plurality of cells for
housing reticles. The racks are electrically grounded, and the
cells are made metallic and electrically connected to the racks to
secure electrostatic shielding properties. With the purpose of
imparting antiseismic properties to the system, the shelves are
made with a slope inside the racks, the slope being preferably
about 8.degree..
Inventors: |
Kuo, Kun-Tsang; (Hsinchu,
TW) |
Correspondence
Address: |
TUNG & ASSOCIATES
Suite 120
838 W. Long Lake Road
Bloomfield Hills
MI
48302
US
|
Assignee: |
Taiwan Semiconductor Manufacturing
Co., Ltd.
|
Family ID: |
29216606 |
Appl. No.: |
09/975663 |
Filed: |
October 10, 2001 |
Current U.S.
Class: |
312/201 ;
211/201 |
Current CPC
Class: |
H05K 9/0067 20130101;
A47B 53/02 20130101; H01L 21/67769 20130101 |
Class at
Publication: |
312/201 ;
211/201 |
International
Class: |
A47B 087/00 |
Claims
What is claimed is:
1. A reticle storing movable rack system comprising: a plurality of
flat tracks fixedly secured to a floor, a plurality of rows of
storage units, each of said storage units comprising of a plurality
of independent racks interconnected with each other and adapted to
be moved as a single row along flat tracks of said plurality of
flat tracks, each of said racks being electrically grounded, and an
operator engageable drive assist mechanism to move rows of said
plurality of rows, wherein each of said racks comprises shelves
with plurality of cells for housing reticles therein, said cells
having electrostatic shielding properties.
2. The system according to claim 1, wherein said electrostatic
shielding properties are secured by making said cells metallic and
electrically connecting them to said racks.
3. The system according to claim 1, wherein, with the purpose of
imparting antiseismic properties to the system, said shelves are
made with a slope directed inside said racks.
4. The system according to claim 3, wherein said slope is about
8.degree..
5. The system according to claim 3, wherein rows of said plurality
of rows are made double-sided.
6. A reticle storing movable rack system comprising: a plurality of
flat tracks fixedly secured to a floor, a plurality of rows of
storage units, each of said storage units comprising of a plurality
of independent racks interconnected with each other and adapted to
be moved as a single row along flat tracks of said plurality of
flat tracks, and an operator engageable drive assist mechanism to
move rows of said plurality of rows, wherein each of said racks
comprises shelves with plurality of cells for housing reticles
therein and wherein, with the purpose of imparting antiseismic
properties to the system, said shelves are made with a slope
directed inside said racks.
7. The system according to claim 6, wherein said slope is about
8.degree..
8. The system according to claim 6, wherein rows of said plurality
of rows are made double-sided.
9. The system according to claim 6, wherein each of said racks is
electrically grounded and said cells have electrostatic shielding
properties.
10. The system according to claim 9, wherein said electrostatic
shielding properties are secured by making said cells metallic and
electrically connecting them to said racks.
11. A reticle storing movable rack system comprising: a plurality
of flat tracks fixedly secured to a floor, a plurality of rows of
storage units, each of said storage units comprising of a plurality
of independent racks interconnected with each other and adapted to
be moved as a single row along flat tracks of said plurality of
flat tracks, and an operator engageable drive assist mechanism to
move rows of said plurality of rows, wherein each of said racks
comprises shelves with plurality of cells for housing reticles
therein, said shelves being made with a slope directed inside said
racks and said cells having electrostatic shielding properties.
12. The system according to claim 11, wherein said electrostatic
shielding properties are secured by making said cells metallic,
electrically connecting said metallic cells to said racks, and
electrically grounding said racks.
13. The system according to claim 11, wherein said slope is about
8.degree..
14. The system according to claim 11, wherein rows of said
plurality of rows are made double-sided.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates in general to semiconductor
manufacturing industry, and more specifically to movable racks for
storing reticles. Even more specifically, the invention relates to
reticle storing movable rack system having
anti-electrostatic-damage and earthquake-proof properties.
[0003] 2. Description of the Related Art
[0004] It is well known in the art that in the fabrication of
semiconductor devices and integrated circuits, electrostatic
discharge is a phenomenon that commonly occurs during the handling
of semiconductor integrated circuit devices and one of the main
factors causing damage of the integrated circuits that may turn
into a very critical problem immediately affecting stable yield and
smooth production.
[0005] As an example, the static electricity problem may arise when
an operator walks on a carpet with semi-conductor wafers.
Electrostatic voltage of about a few hundred volts may exist on
one's body and wafers if relative humidity is high. With humidity
being at its low, the electrostatic voltage may reach as high as
about a few thousand volts. If a conductive object occasionally
contacts the wafers, a substantial electrostatic damage could occur
and damage the integrated circuits on the wafers. Electrostatic
damage is an especially serious problem for fabrication of a
complementary metal-oxide semiconductor device.
[0006] Damage due to electrostatic charge, which may accumulate for
various reasons and produce potentially destructive effects on an
integrated circuit device, typically can occur during a testing
phase of the fabrication of the integrated circuits or during
assembly of the integrated circuit onto a circuit board, as well as
during use of equipment, into which the integrated circuit has been
installed. Damage to a single integrated circuit due to poor
electrostatic damage protection in an electronic device can
partially, or sometimes completely, hamper its functionality.
Electrostatic damage protection for semiconductor integrated
circuits is, therefore, a reliability issue.
[0007] In semiconductor industry, the above-identified problem of
electrostatic damage and protection there against may exist with
regard to various articles. Those may include silicon wafers,
reticles, or other substrates used for building integrated circuit
devices. (By reticle, a transparent ceramic substrate is understood
that is coated with a metallic layer forming a pattern for an
electronic circuit. The reticle is generally used in an imaging
step during a photolithographic process where a pattern of a
circuit is reproduced on the surface of an electronic substrate,
i.e., on a wafer surface.) In a semiconductor fabrication facility,
static electricity or electrostatic discharge frequently develops
on surfaces of articles made of insulating materials when they are
touched or rubbed by other insulating materials such as insulating
gloves. The electricity is produced based on a triboelectricity
theory. The discharge of the static electricity to machines and to
human operators can cause damage not only to semiconductor wafers
but to process tools as well. Sometimes, it may even cause injury
to a machine operator.
[0008] In semiconductor industry, specifically in manufacturing
integral circuits, idle reticles, i.e. those not involved in a
current manufacturing process, are usually stored on racks.
Reticles on the racks are subjected to electrostatic damage.
Capacity of existing racks is not sufficient enough. Also, there is
high risk of them being damaged in case of earthquake. Therefore, a
need exists to provide racks for storing reticles that would be
free of drawbacks of existing structures used for the same
purpose.
[0009] On the other hand, known in the art are various structures
of sliding storage racks that seemingly could be used for storing
reticles. For example, Potter, U.S. Pat. No. 3,601,257, discloses a
file apparatus having movable racks. The apparatus has parallel
tracks, between which rollers movable along the tracks suspend
racks supporting looseleaf binders. The rack is tubular and has an
open-ended channel, in which a T-bar is disposed. A plate stem
depending from the T-bar through a slot lengthwise of the bottom of
the rack carries a binder. The T-bar is slidably inserted or
removed through an end of the channel as a unit with the binder. A
nameplate clipped to an end of the rack identifies the contents of
the binder. A cutaway at each end of the rack allows easy insertion
or removal of the T-bar. The apparatus may be formed to carry
tracks extending in a longitudinal as well as in a lateral
direction, permitting selective use of either set of tracks to
support the racks. The apparatus may also be formed of groups of
posts supporting tracks at various levels between them. The latter
construction is extensible to include additional levels of tracks;
and is of a knockdown nature permitting ready assembly or
disassembly of its component parts.
[0010] In another U.S. Pat.(No. Re. 35,047), Potter disclosed a
self-sliding storage rack for 3480 cartridges. In accordance with
the invention, cartridge storage racks are arranged end-to-end and
back-to-back in stationary rows. Additionally, adapted to be
mounted to slide alongside the front of each row are similar racks.
The number of stationary racks, without disturbing existing racks,
may be extended to the extent of room space; and track elements may
be added as needed to the extent of the rows of stationary racks
for sliding additional slide racks. The slide racks slide relative
to the stationary racks in such manner as not to block full access
of an individual to the stationary racks; and means is provided to
brake the sliding racks against over-travel relative to the
stationary racks.
[0011] Latino, U.S. Pat. No. 5,341,944, discloses a modular library
system for computer cartridges has stationary and mobile racks.
Each of the racks comprises a plurality of spaced "T" shaped
vertical supports. The vertical supports define vertical spaces for
receiving cartridge holding trays or packs. The "T" shaped supports
have tabs for holding the packs. A top panel, a rear panel, a
mounting base, and a spreader interconnect the "T" shaped supports.
The spreader interlinks with all the vertical supports for
providing structural rigidity.
[0012] Croker, U.S. Pat. No. 5,439,281 discloses a movable storage
system that has one or more storage units, a plurality of flexible
track elements conformable with an irregular supporting surface,
and an individual base structure, which supports each storage unit
for movement along the track elements through roller members
associated with particular track elements. The flexible track
elements have a pair of cylindrical longitudinally extending track
members supported by a flexible base. The roller members or wheels
have a generally U-shaped external contour, which encompasses the
track elements and prevents derailing of the storage units.
[0013] Theken, U.S. Pat. No. 5,624,166, discloses a mobile storage
cabinets, which are "slide-by" cabinets, that is, the cabinets ride
on a carriage in a longitudinal direction on a cabinet track to
allow access to the contents of a posterior cabinet. The top
surface of the posterior cabinet includes an anti-tip track, which
is substantially parallel to the cabinet track. The anti-tip track
has a cylindrical groove with a longitudinally extending top
opening, which forms a slot. A football-shaped is captured in the
groove to form a journaled follower, which optionally includes
roller bearing surfaces, vertical link extends through the slot and
is joined at a fixed angle to a horizontal link, which is pivotally
joined to a bracket member attached to the back surface of a front
cabinet. The bracket extends beyond the top of the cabinet. If
multiple rows of cabinets are used, the anti-tip assemblies for the
cabinets of each row are stepped so that they clear the top of
posterior cabinets.
[0014] Sarno, U.S. Pat. No. 5,683,155, discloses an apparatus for
moving laterally accessible file storage or similar shelving units,
from a stowed densely packed lateral array of such units,
longitudinally to a full access position. The apparatus includes a
wheeled carriage, which travels over a flat supporting track laid
in the path of the carriage as the unit is rolled longitudinally.
The flexible track has a leveling feature, which can accommodate
uneven or varying level base floor surfaces. Return movement of the
carriage picks up the flexible track leaving no exposed portion of
the apparatus when the unit is stowed.
[0015] Baker et al., U.S. Pat. No. 6,112,917, discloses a large
capacity mobile storage system having a plurality of storage units
and a plurality of interconnected support assemblies for rolling
movement. Each of the support assemblies includes a frame and a
pair of spherical shaped hardened steel support wheels. Only one of
the support assemblies includes a pair of guide rollers disposed
perpendicular to its associated support wheels in order to maintain
rolling movement of the storage system along a linear path. The
support wheels of the other support assemblies are allowed to move
independently from one another in order to prevent the scrubbing
action of the supporting apparatus. The supporting assemblies also
include a drive track and a sprocket disposed at one end of the
storage unit with a drive mechanism. This feature helps to keep the
floor area between the flat tracks uncluttered. The apparatus
compensates for a significant degree of unevenness and undulation
of the flat tracks caused by an uneven floor upon which the flat
tracks are mounted.
[0016] Baker et al., U.S. Pat. No. 6,158,601, discloses a modular
storage apparatus for movably supporting one or more storage units
in front of a plurality of non-movably supported storage units. The
apparatus comprises a plurality of independent, modular base
sections each having a pair of tracks thereon, which are securable
together via cam lock coupling devices to form a single, rigid,
lightweight, elongated base assembly. A leveling and supporting
system associated with each base unit enables the entire base
assembly to be precisely leveled. The base units each support at
least one carriage unit, which in turn supports an independent
storage unit thereon. An anti-tip system prevents each movable
storage unit from tipping or leaning beyond a predetermined degree.
The modular construction enables the apparatus to be easily and
conveniently shipped, packaged and handled and the assembled base
assembly does not need to be secured to a supporting floor.
[0017] All the advantages of the above-described devices
notwithstanding, neither of them seems to be adapted for storing
reticles. They do not address the problem of electrostatic damage
protection. Neither of them deals with earthquake protection. The
above-described prior art references do not disclose any suggestion
as to the way of modifying the respective structures to solve those
problems.
[0018] Therefore, the primary object of the present invention is to
provide a movable rack system that, while keeping advantages of the
racks known in the art, would at the same time be suitable for a
specific purpose--to store reticles.
[0019] Another object of the present invention is to provide a
movable rack system for storing reticles that would secure the
reticles against electrostatic damage.
[0020] Yet another object of the present invention is to provide a
movable rack system suitable for storing reticles that, along with
the ESD protection, would protect reticles against from falling out
of the racks during a moderate earthquake.
SUMMARY OF THE INVENTION
[0021] Providing a movable rack system attains the above-identified
objects of the invention. According to the present invention, a
reticle storing movable rack system comprises a plurality of flat
tracks fixedly secured to a floor. There is provided a plurality of
rows of storage units. Each row has a plurality of independent
racks interconnected with each other, which racks are adapted to be
moved as a single row along the flat tracks. Provided also is a
user engageable drive assist mechanism to move the rows. Each of
the racks comprises shelves with plurality of cells for housing
reticles therein. The racks are electrically grounded, and the
cells have electrostatic shielding properties.
[0022] Making the cells metallic and electrically connecting them
to the racks secure the electrostatic shielding properties.
[0023] With the purpose of imparting antiseismic properties to the
system, the shelves are made with a slope directed inside the
racks.
[0024] The slope is selected to be preferably about 8.degree..
[0025] To further increase capacity of the system, the rows can be
made double-sided.
BRIEF DESCRIPTION OF DRAWINGS
[0026] The above-mentioned and other objects, advantages and
features of the present invention will be in more detail
illustrated in and will become more apparent to those skilled in
the art from the ensuing specification and subjoined claims, when
considered in conjunction with the accompanying drawings, in
which:
[0027] FIG. 1a is a side view of a row of storage units of the
system according to the present invention;
[0028] FIG. 1b is a front view of a row of storage units of the
system according to the present invention; and
[0029] FIG. 2 is a photo fragment of a plurality of rows of a pilot
model of the system according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] Referring now to FIGS. 1a, 1b, and 2, a movable rack system
10 for storing reticles comprises a plurality of rows of storage
units 12. Each row consists of plurality of independent racks 14
interconnected to each other in such a way that they are adapted to
be moved as a single row to permit access between any pair of
adjacent rows of storage units 12. The racks 14 comprise shelves 16
carrying cells 18. Each of the cells 18 houses a reticle in a box
(not visible in the Figures).
[0031] There also provided flat tracks 20 fixedly secured to a
floor 22, whereas the racks 14 are equipped with wheels 24, and the
racks 14 are made movable along the tracks 20. A drive assist
mechanism enables an operator to easily move its associated rack
row in a storage unit 12 along the tracks 20 by providing a
mechanical advantage through a suitable arrangement of gears. Each
drive assist mechanism includes a hand assembly 26, which the
operator turns rotationally to impart linear movement to its
associated storage unit 12 via a drive chain (not shown). Drive
assist mechanism of this kind are well known in the art and
therefore are not discussed in more detail.
[0032] To cope with the electrostatic damage problem, a number of
measures are to be taken according to the present invention. Walls
and floor coverings are built with slightly conductive materials
such that electrical charges can be routed to ground. The coverings
are connected to the metal framework of the wall systems, which is
connected to the planar ground (not shown in the Figures). The
racks 14 and tracks 20 are made of metal. The tracks 20 are
grounded that is symbolically shown by reference numeral 28.
Therefore, an electrical connection is established between the
racks 14 and the grounding 28. Besides grounding the racks 14
through the tracks 20 and floor 22, they can be additionally
grounded through electrically connecting them to overhead joists
(not shown), which in turn are electrically connected to the
walls.
[0033] According to the present invention, the cells 18 exhibit
electrostatic shielding properties. They are made of metal, for
example light steel, and electrically connected to the racks 14.
The connection can be carried out by electrically joining the cells
to the rack through the shelves provided the latter are also
metallic, or directly, not relying on the shelves.
[0034] To additionally contribute to anti-electrostatic-damage
protection, an operator can also be grounded since the body
constitutes an electric charge.
[0035] The above-discussed anti-electrostatic-damage measures and
features lead to impressive results. Whereas the number of
electrostatically damaged reticles after 24, 48, and 72 hours of
being stored in the prior art system was 7, 13, and 17,
respectively, none of reticles was electrostatically damaged after
24, 48, and 72 hours of being stored in the system according to the
present invention.
[0036] To conveniently increase capacity of the system, the rows of
racks 14 can be made double-sided, that is arranged back-to-back as
shown by 14a and 14b in FIG. 1. Calculations show that making the
racks double-sided and movable can increase the capacity of the
idle mask storage up to 250% (say, from 6000 reticles up to 15,000
reticles).
[0037] Though it is believed that the above-described system is
relatively stable due to its structure and thus can hold out
against a non-catastrophic earthquake, the present invention adds
to the system's earthquake-proof features. According to the
invention, the shelves 16 are made slant, with a slope directed
inside the rack 14, toward its back that is shown in FIG. 1a by
dotted double lines and can also be visible in FIG. 2 by an angle
between a stanchion 30 and edges 32 of the otherwise rectangular
cells 18 placed on the shelves 16. Preferably, the angle is
selected to be about 8.degree.. Making the shelves with the slope
prevents the boxes with the reticles from falling down out of the
cells in the time of earthquake.
[0038] While the preferred embodiment of the present invention has
been disclosed herein above, it is to be understood that this
embodiment is given by example only and not in a limiting sense.
Those skilled in the art may make various modifications and
additions to the preferred embodiment chosen to illustrate the
invention without departing from the spirit and scope of the
present contribution to the art. Accordingly, it is to be realized
that the patent protection sought and to be afforded hereby shall
be deemed to extend to the subject matter claimed and all
equivalence thereof fairly within the scope of the invention.
* * * * *