U.S. patent application number 13/005020 was filed with the patent office on 2011-05-05 for adjustable width cassette for wafer film frames.
This patent application is currently assigned to TEXAS INSTRUMENTS INCORPORATED. Invention is credited to Zainudin Bin Mohamed.
Application Number | 20110100937 13/005020 |
Document ID | / |
Family ID | 33451975 |
Filed Date | 2011-05-05 |
United States Patent
Application |
20110100937 |
Kind Code |
A1 |
Mohamed; Zainudin Bin |
May 5, 2011 |
Adjustable Width Cassette for Wafer Film Frames
Abstract
An expandable width cassette for storing and transporting thin
planar objects of different widths is provided. The cassette 10
includes two side panels 12 of fixed height opposite and parallel
to one another having a series of elongated slots on the inner
surface of the side panels for supporting planar objects, a sliding
bar assembly 13 on the bottom side of the cassette, and an
adjustable length panel 14 on the top side of the cassette. Spring
loaded press screws 143 disengaged from locator holes at predefined
locations in the top panel allow the cassette width to be altered
by pushing or pulling the side panels. A wafer film frame cassette
includes a back stop mechanism which further serves to align with a
frame notch.
Inventors: |
Mohamed; Zainudin Bin;
(Puchong, MY) |
Assignee: |
TEXAS INSTRUMENTS
INCORPORATED
Dallas
TX
|
Family ID: |
33451975 |
Appl. No.: |
13/005020 |
Filed: |
January 12, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10452341 |
Jun 2, 2003 |
7891937 |
|
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13005020 |
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Current U.S.
Class: |
211/41.18 |
Current CPC
Class: |
H01L 21/6732
20130101 |
Class at
Publication: |
211/41.18 |
International
Class: |
H01L 21/67 20060101
H01L021/67; B65D 85/90 20060101 B65D085/90 |
Claims
1. An adjustable width cassette for holding and transporting thin
planar objects, the cassette comprising: a substantially open front
side for insertion of said thin planar objects; two side panels
positioned opposite and parallel to each other with a plurality of
elongated opposing slots extending horizontally along the inner
surface of each of said side panels for supporting said thin planar
objects along a portion of the perimeter of said thin planar
objects; an expandable, sliding bar assembly providing connection
between said side panels on the bottom side of the cassette; an
adjustable length panel providing connection between said side
panels on the cassette top side; and a spring-loaded locking means
for locking the adjustable length panel at one of two predetermined
lengths.
2. The adjustable width cassette of claim 1 wherein said adjustable
length panel includes a screw frame having one or more spring
loaded press screws, and a base plate having a slot with a
plurality of locator holes attached by brackets to said side
panels.
3. The adjustable width cassette of claim 2 wherein said locator
holes are positioned at predefined locations in the base to control
the cassette width.
4. The adjustable width cassette of claim 2 wherein each of said
spring loaded press screws comprises a screw having a head larger
in diameter than that of the screw body, and a spring wound around
said screw body.
5. The adjustable width cassette of claim 2 wherein said adjustable
length panel includes a spring loaded screw wherein the spring has
sufficient recoil strength to disengage the screw from a locator
hole.
6. The adjustable width cassette of claim 1 wherein said side
panels are free to be moved either inwardly or outwardly.
7. The adjustable width cassette of claim 1 wherein said sliding
bar assembly comprises a frame having two sections and a sliding
bar and a rigid cover.
8. The adjustable width cassette of claim 1 wherein the length of
said sliding panel on the bottom side of said cassette is
determined by the length of the adjustable top panel.
9. The adjustable width cassette of claim 1 wherein the cassette is
of a fixed height and depth.
10. The adjustable width cassette of claim 1 which further includes
a back stop mechanism having no connection between the side
panels.
11. The adjustable width cassette of claim 1 wherein the side
panels comprise a light weight machined metal alloy.
12. The adjustable width cassette of claim 1 wherein the side
panels comprise a molded plastic.
13. The adjustable width cassette of claim 10 wherein the backstop
comprises a compliant polymeric material.
14. An adjustable width cassette for holding and transporting wafer
film frames, the cassette comprising: a substantially open front
side for insertion of said wafer film frames; two side panels
positioned opposite and parallel to each other with a plurality of
elongated opposing slots extending horizontally along the inner
surface of each of said side panels for supporting the wafer film
frames along a portion of the frame perimeter; an expandable,
sliding bar assembly providing connection between said side panels
on the bottom of the cassette; an adjustable length panel providing
connection of said side panels on the cassette top side.
15. The adjustable width cassette of claim 14 further comprising a
back stop mechanism including a rod positioned between a pair of
brackets located near the top and bottom on the inside of one side
panel.
16. The adjustable width cassette of claim 15 wherein said rod is
positioned and sized to engage with a notch in said wafer film
frame.
17. The adjustable width cassette of claim 15 wherein said back
stop mechanism includes more than one pair of brackets of different
lengths.
18. The adjustable width cassette of claim 14 wherein said panels
comprise an aluminum alloy.
Description
FIELD OF THE INVENTION
[0001] The invention relates generally to semiconductor processing
equipment, and more particularly to cassettes for wafers on film
frames.
BACKGROUND OF THE INVENTION
[0002] The semiconductor industry, as well as unrelated industries,
frequently hold and transfer thin planar objects in cassettes
having a series of parallel, spaced apart horizontal slots which
receive and hold a single planar object in each slot. Semiconductor
wafers are frequently transferred from one processing station to
another via cassettes. In some cases, cassettes are sized and
shaped to hold film frames or other similar devices upon which a
wafer has been mounted for processing and/or transporting.
[0003] Cassettes are used within the semiconductor industry
primarily in processes which retrieve and process one wafer at a
time. In particular, wafer cassettes are often used in conjunction
with chemical mechanical planarization machines and in the
packaging and assembly operations film frame cassettes are used in
conjunction with sawing and die attach equipment. Wafers or the
film frames upon which wafers have been mounted are typically
loaded and unloaded from a cassette automatically by the processing
equipment or a robotic mechanism. A robotic arm selectively
retrieves the wafer or frame from the cassette, and transports the
work pieces one at a time to a processing station. In the case of
film frame cassettes, the frames are individually removed for
processing, usually by an automated load/unload interface device on
sawing or die attach equipment, and it is necessary that the frames
be aligned and positioned in the correct location to avoid
malfunction of the interface device.
[0004] The diameter of wafers has changed several times in recent
years as larger wafers and processing equipment for larger diameter
wafers has become available to the industry, and as the economics
of larger diameter wafers has become evident. It is not uncommon
for backend facilities, including packaging and assembly
manufacturing to process wafers of more than one diameter,
typically 150, 200, 250, and 300 mm. In order to hold the wafers
and frames securely in place, each cassette is sized to accommodate
a given wafer and/or film frame size. Therefore, the manufacturing
facilities which store and transport wafers or wafers on film
frames must store various frame and cassette sizes, and must make
changes to the processing equipment or transport equipment for each
different size wafer or frame. Typically, a cassette for each
specific wafer size differs in width, height, depth, and other
design features from a cassette for a different size wafer. The
multiplicity of cassette sizes adds to storage space requirements,
as well as inventory cost.
[0005] Modifications to automated equipment or equipment interfaces
in order to facilitate different wafer and frame sizes result in
costly work stoppages and increased cycle time. Equipment changes,
particularly those involving mechanical modifications to interface
mechanisms are labor intensive, time consuming, and are subject to
set-up errors.
[0006] A significant problem associated with multiple cassette
sizes requiring equipment set-up changes is the increased
probability of improper alignment resulting in damage to costly
wafers as a result of frames jamming into each other and sliding
across the surface of a wafer.
[0007] Industries unrelated to semiconductors have similar issues
with a multiplicity of cassette sizes; therefore, it would be an
advantage not only to the semiconductor industry, but to unrelated
industries as well, if a solution to the problems associated with
cost of multiple cassette sizes, the equipment changes, and
preparation required for handling multiple cassette sizes could be
eliminated.
SUMMARY OF THE INVENTION
[0008] In accordance with an embodiment of the invention, a
cassette which may be expanded or contracted in width for storing
and transporting thin planar objects of different widths is
provided. A first embodiment of the adjustable width cassette
includes two side panels of fixed height opposite and parallel to
one another having a series of elongated slots on the inner surface
of the side panels for supporting the objects along a portion of
the perimeter, an expandable sliding bar assembly on the bottom
side of the cassette contacting and joining the side panels, and an
adjustable length panel on the top side of the cassette having
spring loaded press screws with holes for screw engagement at
predefined locations.
[0009] The front of the cassette is open to allow objects to be
inserted into the cassette and to be supported on the side slots.
Preferably, the depth and height of the cassette are a function of
the side panels and are fixed. A stop mechanism is provided on the
cassette backside to prevent the planar objects from escaping, or
from extending outside the cassette. The stop mechanism extends
along one side of the back, and has no connection between the two
side panels. The adjustable width cassette is preferably comprised
of a lightweight durable material such as a machined metal or a
molded plastic.
[0010] The adjustable length panel on the cassette top includes a
base plate having a slot with a plurality of locator holes and is
attached to the side panels by brackets. The panel further includes
a screw frame having spring loaded screws which may be depressed to
disengage from locator holes in the base plate. The holes
effectively form stop positions and are placed at predefined
locations along the length of the plate to permit the cassette
width to be changed.
[0011] The spring loaded press screws include a screw having a head
larger in diameter than the body, and a spring wound around the
body. The springs have sufficient recoil strength to disengage from
locator holes when pressed and released.
[0012] Use of the adjustable width cassette is accomplished by
pressing to disengage the screw(s), the frame is then free to move
along the slot in the base plate, the side panels may be pulled
apart until a new locator hole is encountered, and the screws
become reengaged to form a wider cassette. Alternately, the press
spring loaded screws may be depressed to become disengaged from the
locator holes and the sides pushed together until an inner stop
position is encountered for a smaller width cassette.
[0013] A sliding bar assembly on the bottom of the cassette
includes a two part frame with a sliding bar, and a rigid cover.
The sliding mechanism is controlled by movement of the top side
adjustable length panel.
[0014] In an embodiment wherein the adjustable width cassette is a
wafer film frame holder, the cassette includes a rod of
approximately the same height as the side panels positioned on the
back side of the cassette. The rod is held by a pair of brackets
extending from one of the side panels, and is positioned to mate
with the notch in a given film frame, thereby forming both a stop
mechanism to preclude frames from extending beyond the cassette
back side, and an alignment feature to insure correct frame
orientation. The brackets are placed near the top and bottom of the
cassette. The rod may be placed in a second set of brackets of a
different length for a different frame size.
[0015] An adjustable width cassette for semiconductor wafers
includes more narrow slots than a cassette for film frames, and the
backstop mechanism is of a material sufficiently compliant to avoid
chipping or damage to brittle wafers, such as a molded plastic.
[0016] In accordance with other embodiments of the invention, the
adjustable width cassette is applicable to various thin planar
materials of different widths which require horizontal storage and
or transporting, and is not limited to the semiconductor
industry
[0017] The expandable width cassette of this invention reduces the
amount of storage space required in a manufacturing facility for
multiple fixed width cassettes, reduces inventory costs, reduces
equipment set-up time, and minimizes errors associated with use of
different single width cassettes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a perspective view of an embodiment of the
adjustable width cassette of the current invention.
[0019] FIG. 2 schematically demonstrates the adjustable width
cassette in an expanded mode.
[0020] FIG. 3 schematically demonstrates the cassette in a fully
contracted position.
[0021] FIG. 4a is a detailed cross sectional view of a portion of
the adjustable length panel including the screw frame, spring
loaded screws, and locator holes in the base plate.
[0022] FIG. 4b is a detailed top view of the slot and holes in the
base plate.
[0023] FIG. 5a is a top view of the sliding bar assembly in the
bottom of the cassette.
[0024] FIG. 5b is a cross sectional view of the sliding bar
assembly.
[0025] FIG. 6 is a top view of a film frame and wafer in the
adjustable width cassette.
[0026] FIG. 7a illustrates an expandable width cassette with film
frame back stop rod and brackets.
[0027] FIG. 7b illustrates in more detail a portion of a side panel
with two pairs of brackets for a back stop rod.
[0028] FIG. 8 is a top view of a film frame notch engaged with a
back stop rod.
DETAILED DESCRIPTION OF THE INVENTION
[0029] FIG. 1 provides a perspective view of a first embodiment of
the invention, an adjustable width cassette 10 for holding and
transporting planar objects. The cassette 10 includes a
substantially open front facing side 11 to allow insertion of thin,
planar objects, a pair of vertical side panels 12 opposite and
parallel to each other having a plurality of elongated opposing
horizontal slots 121 on the inner surface for supporting the planar
members, a sliding bar assembly 13 on the bottom side of the
cassette providing connection between the side panels 12, and an
adjustable length horizontal panel 14 on the top side of the
cassette providing connection between the side panels 12. The
horizontal structures, a sliding bar assembly 13 on the bottom and
the adjustable length panel 14 on the top, are approximately
centered front to back of the cassette in order to provide
dimensional stability to the vertical side panels 12.
[0030] The adjustable length panel 14 on the cassette top side is
an assemblage which includes the significant elements to permit
adjustment and fixing of the cassette width. The panel assemblage
14 includes a rigid plate 141 having a slot with locator holes
(hidden from view) connected to each of the vertical side panels 12
by brackets 247 as shown in FIG. 2 on which the plate may move, and
a screw frame 142 atop and near the center of the assemblage and
having spring loaded press screws 143 which mate with locator holes
at predefined locations. Locator holes are spaced along the length
of the plates 141 to engage the screws 143 and fix each
predetermined cassette width.
[0031] The spring loaded press screws include a screw having a head
larger in diameter than the body, and a spring wound around the
body. The springs have sufficient recoil strength to disengage from
locator holes when pressed and released.
[0032] FIG. 2 schematically illustrates the mechanism whereby the
width of the cassette 20 is increased. Spring loaded press screws
243 in the adjustable length top panel 24 are moved vertically by
pressing and releasing; recoil of the spring engages the screw head
causing the screw to disengage from locator holes 245 in the base
plate 241, thereby freeing the plate for lateral movement on the
brackets 247. With the screws disengaged from the locator holes,
side panels 22 of the cassette may then be pulled laterally, as
indicated by arrows 246, until a more widely spaced set of locator
holes are encountered, and the spring loaded screws become
reengaged with the new locator holes. In the same expansion step,
the slide bar 23 on the cassette bottom side is expanded
lengthwise, thus providing a bottom support for a wider
cassette.
[0033] Alternately, to form a more narrow cassette 30 as shown in
FIG. 3, the press spring screws 343 are moved vertically until they
become disengaged from locator holes and the cassette sides 32 are
then pushed inwardly, as indicated by arrows 348, until a different
set of locator holes 345 within the slot in the plate 341 are
encountered and engaged. The slide bar 33 on the bottom follows the
width set by the top side adjustable length panel 34.
[0034] In FIG. 4a, a cross section of a portion of the adjustable
length panel assemblage including the screw frame 442 further
illustrates the mechanism for adjusting the cassette width. A pair
of spring 448 wound screws 443 having heads 449 larger in diameter
than the screw body is set in the screw frame 442. Each of the
screws 443 is engaged with a mating locator hole 445 in a plate
441. It can be seen that a different set of holes 446 are included
in the plate and the holes are set equidistant from each other so
that the screws 443 may be engaged with a different pair of holes,
thus allowing a different width of cassette to be formed when the
screws are released and the cassette side panels are pushed apart
or together.
[0035] In FIG. 4b, a top view of the base plate 441 illustrates the
slot 445 in the plate with enlarged holes 446 which may engage the
screws and form a stop position. The base plate 441 slides on the
brackets 447 which are connected to the side panels 42.
[0036] A pair of screws with mating holes has been illustrated in
FIG. 4a; however, in an alternate embodiment having a different
panel width, the number of screws and holes placed along the length
of the panel may be increased or decreased.
[0037] In FIGS. 5a and 5b, the sliding bar assembly 53 on the
bottom of the cassette connects the two vertical side panels
521,522, and the assembly 53 comprises two major components. The
first component is a frame having two sections 531 and 532 with a
sliding bar 533, and the second component, a rigid cover. The two
section frame 531, 532 is shown from a top view in FIG. 5a and a
cross sectional view in FIG. 5b. The frame includes a smaller
section 531 which is attached to one cassette side 521, and a
larger section 532 on which the bar 533 slides is attached to the
opposite cassette side panel 522. In FIG. 5b, the frame sections
531,532 include a recess 534 equal to or greater than the thickness
of the sliding bar 533. The sliding bar 533 is positioned and moves
within the recess 534 in the frame sections 531,532.
[0038] The length of the cover 535 is equal to the shortest
distance to which the inner sides of the cassette can be set, and
thereby the cover may form a hard stop for cassette minimum width.
The length of the bottom sliding assembly 53 is established by the
adjustable length panel on the cassette top side, and the bottom
sliding assembly 53 acts as a slave.
[0039] In a preferred embodiment, the depth and height of the
cassette are a function of the side panels and are fixed.
[0040] A stop mechanism is provided on the cassette backside to
prevent the planar objects from escaping, or from extending outside
the cassette. Because the cassette width is variable, it is
desirable that a stop for the backside be attached to one or both
sides, but that there be no connection between the cassette sides
which could interfere with the width adjustment. The back stop may
be a solid or perforated element of sufficient length to preclude
objects being stored from extending beyond the cassette.
Preferably, the back stop will extend from one side panel between
the top and bottom.
[0041] In an embodiment of the adjustable width cassette to be used
for holding semiconductor wafers comprising a brittle material such
as silicon, the back stop material is of sufficiently compliant
material to prevent chipping the wafer edges. A polymeric material
such as Teflon.TM. or a silicone is preferred.
[0042] The adjustable width cassette preferably comprises a
lightweight durable material such as a machined metal or a molded
plastic.
[0043] In a second embodiment, the adjustable width cassette is a
film frame holder for storing and transporting semiconductor
wafers. A film frame holder is typically used to position and
secure a wafer on tape by a controlled release adhesive during the
processes of sawing the wafer into individual chips, transporting
the frame with sawed wafer to a pick and place equipment, and
aligning the wafer in a pick and place equipment.
[0044] In FIG. 6, a top view of the adjustable width cassette 60 is
shown with a film frame 67 having a semiconductor wafer 68 adhered
to a support film 69. Curved sides of the frame 67 rest on slots in
opposite side panels 62 of the cassette. The film frame 67 is
typically fabricated with flat sides adjacent to the curves sides.
Spring loaded screws 643 in the top panel 64 engage in holes at
predefined locations to secure the cassette width for the selected
frame and wafer width.
[0045] Diameter of the wafer 68 is a major determining factor in
the film frame 67 dimension. The film area 69 within the frame is
larger than the wafer 68 in order to avoid damage to a dicing saw
blade if it were to encounter the rigid metal frame. However, it is
preferable that the frame size and requisite cassette size be as
small as the wafer permits in order to avoid the need for excessive
factory storage space.
[0046] The frame 67 has one or two flat sides 671 for correct
alignment to the cassette and to provide a surface which does not
extend beyond the cassette front and back sides. The frame further
includes at least one notch 672 for alignment at the pick and place
equipment.
[0047] The adjustable width cassette as shown in FIG. 1 may be used
to support and transport thin planar objects, such as wafers,
disks, plates, or a number of other objects. For different types of
objects to be handled, the back side of the cassette may require
alternate stop mechanisms to control the objects from being pushed
through and out the back side of the cassette. In the embodiment as
a film frame cassette, the preferred stop mechanism on the back
side serves dual purposes (1) of precluding frames from escaping
through the back side, and (2) of aligning the notch in the frame
so that correct orientation of the wafer is assured.
[0048] In FIG. 7a, the cassette 70 includes two sets of brackets 71
and 72 extending inwardly from one side panel 702, and a rod 73 of
approximately the same height as the side panel connecting the two
components of one bracket set 71. A more detailed view of the back
stop rod arrangement for a film frame cassette is shown in FIG. 7b.
Each set of brackets 71 and 72, include two components, one of
which is positioned near the top and the second near the bottom of
the cassette. Components of the bracket set placed closer to the
back 71 of the cassette are longer than those of the set of bracket
moved more toward the center, and are located so that the rod 73
will engage the notch of a larger film frame. A smaller diameter
film frame will be engaged by a rod in the shorter bracket, and a
larger diameter frame by a rod positioned in the longer bracket
set. The rod may be moved manually to the desired location. Because
the brackets and rod are attached to a single side 702 of the
cassette, there is no interference with the cassette width
adjustment mechanisms.
[0049] In FIG. 8 from the top view, a film frame 87 with wafer 88
is positioned on a slot in the cassette side panel 802. The rod 83
extending through a bracket 81 has engaged the notch 871 in the
frame 87 causing it to stop. Precise alignment of the film frame
and wafer is a significant asset for automated pick and place
equipment. The equipment typically has a programmed location on the
wafer to begin removing the chips from the wafer tape, and that
location must be correct in order to avoid selecting the wrong
chips.
[0050] This back stop and frame alignment feature has been
illustrate with two locations, however, it is not limited to two
sizes of frames, but additional brackets may be included.
[0051] Width adjustment of the film frame cassette makes use of the
same adjustable length panel on the top side and sliding bar
assembly as shown in FIGS. 2 through 5, and the method for
expanding and contracting the width is the same as previously
described.
[0052] The adjustable width cassette provides a transport and
storage case useful for a number of planar objects wherein the
objects are of different widths. Preferably, the height and depth
of the cassette are fixed, thereby eliminating much of the work
required to adjust equipment interface systems for cassettes having
not only different width, but also different height and depth. The
adjustable width cassette reduces the amount of storage and
inventory of cassettes required for a factory which supports
processing of multiple sized planar objects.
[0053] In an embodiment of a cassette for film frames and wafer,
the frames are typically constructed of a metal such as aluminum or
a steel alloy, and therefore the preferred materials for the film
frame cassette are of a light weight, durable, rigid material such
as an aluminum alloy. In an alternate embodiment, the cassette may
be constructed of a molded plastic of sufficient structural
strength to withstand expansion and contraction.
[0054] It will be recognized that an adjustable width cassette is
applicable for transport and storage of many types of objects, and
that modifications for various applications will become apparent to
those skilled in the art. Therefore, it is intended that the
appended claims be interpreted as broadly as possible.
* * * * *