U.S. patent application number 11/684859 was filed with the patent office on 2007-12-20 for method for packaging contamination vulnerable articles and package therefore.
This patent application is currently assigned to International Business Machines Corporation. Invention is credited to Michael Haag, Rainer Klaus Krause, Gerd Pfeiffer, Markus Schmidt.
Application Number | 20070289896 11/684859 |
Document ID | / |
Family ID | 38860516 |
Filed Date | 2007-12-20 |
United States Patent
Application |
20070289896 |
Kind Code |
A1 |
Krause; Rainer Klaus ; et
al. |
December 20, 2007 |
Method for packaging contamination vulnerable articles and package
therefore
Abstract
A package for the transportation of contamination vulnerable
articles is provided, comprising a closeable plastic container
which is loaded with the respective articles, a first bag made from
plastic surrounding said container, and a second bag made from
plastic wrapping said first bag, wherein said first bag is provided
with a valve-filter arrangement in order to allow a controlled air
stream into said first bag when opening said valve-filter
arrangement.
Inventors: |
Krause; Rainer Klaus;
(Kostheim, DE) ; Haag; Michael; (Rodenbach,
DE) ; Pfeiffer; Gerd; (Poughquag, NY) ;
Schmidt; Markus; (Seibersbach, DE) |
Correspondence
Address: |
INTERNATIONAL BUSINESS MACHINES CORPORATION;DEPT. 18G
BLDG. 300-482, 2070 ROUTE 52
HOPEWELL JUNCTION
NY
12533
US
|
Assignee: |
International Business Machines
Corporation
Armonk
NY
|
Family ID: |
38860516 |
Appl. No.: |
11/684859 |
Filed: |
March 12, 2007 |
Current U.S.
Class: |
206/711 |
Current CPC
Class: |
B65D 33/01 20130101;
H01L 21/67386 20130101; H01L 21/67393 20130101 |
Class at
Publication: |
206/711 |
International
Class: |
B65D 85/86 20060101
B65D085/86 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 19, 2006 |
EP |
06115629.5 |
Claims
1. A package for the transportation of contamination vulnerable
articles, comprising a closeable plastic container which is loaded
with the respective articles, a first bag (4) made from plastic
surrounding said container, and a second bag made from plastic
wrapping said first bag (4), wherein said first bag (4) is provided
with a valve-filter arrangement (6, 16) in order to allow a
controlled air stream into said first bag (4) when opening said
valve-filter arrangement (6, 16).
2. The package according to claim 1, wherein said contamination
vulnerable articles are semiconductor wafers.
3. The package according to claim 1, wherein said valve-filter
arrangement (6, 16) is mounted into a corner portion (2) of said
bag (4).
4. The package according to claim 3, wherein said mounting is
accomplished by welding or heat glueing.
5. The package according to claim 3, wherein said valve-filter
arrangement (6, 16) is directly integrated into the packaging.
6. The package according to claim 1, wherein said valve-filter
arrangement (6, 16) consists of a plastic tube (8) and a filter
element (16) welded thereinto.
7. The package according to claim 1, wherein the second bag is
additionally provided with said valve-filter arrangement (6,
16).
8. The package according to claim 1, wherein said plastic container
is a Front Opening Shipping Box (FOSB).
9. The package according to claim 1, wherein said tubing part (8)
consists of a lower part (10) and a sealed upper part (12) closed
at its top.
10. The package according to claim 1, wherein said filter element
(16) consists of a filter holder (18) and a filter sheet (20).
11. The package according to claim 10, wherein said filter holder
(18) is a U-shaped plastic tube (14).
12. A method for packaging contamination vulnerable articles,
comprising the steps of loading said articles into a closeable
plastic container, surrounding said container with a first plastic
bag (4), and surrounding said container and said first plastic bag
with a second plastic bag, wherein said first plastic bag (4) is
provided with a valve-filter arrangement (6, 16) in order to allow
a controlled air stream into said first bag (4) when opening said
valve-filter arrangement (6, 16).
13. The method according to claim 12, wherein said contamination
vulnerable articles are semiconductor wafers.
14. The method according to claim 12, wherein said second bag is
additionally provided with said valve-filter arrangement (6,
16).
15. The method according to claim 12, wherein said first bag (4) is
opened by cutting off said sealed upper part (12).
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates in general to packages for
contamination vulnerable articles. More specifically the invention
relates to such packages for the transportation of semiconductor
wafers. The invention also pertains to a transportation device for
such contamination vulnerable articles.
[0002] Semiconductor wafers are generally dispatched from the
manufacturer to the purchaser's premises. During transportation,
long distances often have to be covered and the means of transport
may have to be changed frequently. Therefore, there is a
considerable risk that the sensitive semiconductor wafers may be
damaged. Even without any visible damage caused by scratches or
fracturing, impurities may have a considerable adverse effect on
the semiconductor wafers or even make them un-useable for the
desired purpose, namely the fabrication of electronic
components.
[0003] It had been found that after transportation wafer substrates
show significantly higher particle contamination values as compared
to the level right after fabrication. This fact can be easily
explained via the following mechanism:
[0004] Usually, wafer substrates are delivered in transport boxes,
known as Front Opening Shipping Box (FOSB), each containing 25
wafers. The boxes are double bagged to avoid particle
contamination. The bags are individually evacuated during sealing
in order to prevent bursting during, e.g., aircraft transportation.
Examples of such methods can be found, e.g., in US 2002/023413 A1,
JP 54043461 A2, JP 60167414 A2 and JP 60167415 A2.
[0005] When the bags are opened at the customer's premises (usually
by a simple cut with a knife), the pressure gradient between the
exterior of the bag and the interior of the bag causes particles
residing at the bag surface to be sucked in. A fraction of these
particles finally ends up on the wafer box itself, and some of
those consequently also on the wafers through the seal and on the
wafers once the box is opened.
[0006] Additional box cleaning procedures will not completely cure
this problem since particles present in the sealed gap between the
box body and the lid of the FOSB will not be cleaned off but drop
into the boxes interior when the door is removed.
[0007] U.S. Pat. No. 6,131,739 discloses a shock-absorbing package
for a plurality of containers holding semiconductor wafers,
consisting of two half-shells of foamed plastic configured with
recesses into which the containers are placed in a positive-fitting
manner. A container of the FOSB type is described, for example, in
U.S. Pat. No. 6,581,264. A shock-absorbing package of this type is
suitable for reducing the risk of mechanical damage to the
semiconductor wafers during transport.
[0008] In U.S. Pat. No. 6,155,027 there is described an encased and
evacuated container for semiconductor wafers, which should protect
the wafers from contaminating particles during transport.
[0009] U.S. Pat. No. 6,119,865 discloses a container for stacking
of framed wafers comprising means for binding moisture.
[0010] In U.S. 2002/0153526 A1, there is described an encased
container for wafers arranged between shock-absorbing elements in
an outer packaging.
[0011] Finally, DE 10 2004 019 664 B4 and DE 10 2004 063 912 A1
disclose a ready-for-dispatch package for semiconductor wafers and
a method for the ready-for-dispatch packaging of semiconductor
wafers, respectively, comprising a) a closeable plastic container
which is loaded with the semiconductor wafers and has a lid and a
body, a seal between the lid and the body and a particle filter
which is integrated with the container and allows exchange of gas
between the interior space of the container and the external
environment of the container; b) a first sheath made from plastic,
which surrounds the container and rests closely against the
container with the aid of reduced pressure; c) a means for binding
moisture; d) a second sheath made from coated plastic, with a
coating which blocks the passage of moisture and rests closely
against the first sheath and against the container with the aid of
reduced pressure; e) a shock-absorbing structure which embeds the
sheathed container in a positive-fitting manner; and f) an outer
packaging which surrounds the double-sheathed and embedded
container in a positive-fitting manner.
[0012] However, these containers and packages do not solve the
problem that the sensitive wafers are damaged by contaminating
particles when opening the bags at the customer's premises.
Accordingly, there is still a need for packages that do overcome
this disadvantage.
SUMMARY OF THE INVENTION
[0013] It is therefore an object of the present invention to
provide a method for packaging contamination vulnerable articles
that overcomes the above mentioned disadvantage.
[0014] It is a further object of the present invention to provide a
package for use in the above method.
[0015] These and other objects and advantages are achieved by the
method disclosed in claim 1 and the transportation device disclosed
in claim 8.
[0016] Advantageous embodiments of the invention are disclosed in
the dependent claims.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0017] The invention will be described in more detail below in
connection with the accompanying drawings, in which
[0018] FIG. 1 schematically shows one particular embodiment of the
invention;
[0019] FIG. 2 depicts a well-shut tubing according to the
invention;
[0020] FIGS. 3A and 3B depict a filter element according to the
invention; and
[0021] FIGS. 4A and 4B are flow charts comparing the process of
handling the packaged wafers according to the state of the art as
compared to the inventive process.
DETAILED DESCRIPTION OF THE INVENTION
[0022] First of all, it has to be mentioned that the present
invention is not restricted to wafers, but can be used with any
articles that are contamination vulnerable and thus need protection
during shipment. However, in the following, the invention is
described in more detail in view of semiconductor wafers as an
example.
[0023] As has been described before, the boxes containing the
wafers are double-bagged to avoid particle contamination. According
to the invention, the bags are modified in such a way that the
first bag, i.e., the bag wherein the wafer box is packed (or, in
the following called the inner bag), carries a valve as well as a
filter element attached thereto. In a special embodiment, the
second bag, i.e., the bag wrapped around the first bag (or, in the
following called the outer bag) is provided with such a valve and
filter element as well.
[0024] FIG. 1 schematically shows one particular embodiment of the
invention. It has to be mentioned that the skilled worker will
readily think of other embodiments to realize such a valve-filter.
Such designs are usually cost-driven and FIG. 1 shows an
economically priced embodiment. In a corner portion 2 of the inner
standard vacuum sealing bag 4, a valve 6 is arranged. This valve
can also be arranged elsewhere in the bag, however, arranging it in
a corner portion is advantageous because it is easier to attach and
easier to access in order to open the bag. The valve 6,
advantageously formed of one single piece, consists of an elongated
flexible plastic tubing part 8 that is mounted to the sealing bag 4
by welding or glueing or is directly integrated into the packaging.
The tubing part 8 consists of a lower part 10 arranged so as to
extend into the bag 4, and an upper part 12 protruding from the
bag. The upper part 12 is closed at its top. According to FIG. 2,
the flexible plastic tubing 8 (also called weld shut tubing)
consists of a plastic tube 14 closed on one side, i.e., having a
U-shape. Welded into said plastic tube is a filter element 16,
shown in detail in FIGS. 3A and 3B. This filter element may be a
commercially available filter element such as, e.g., an Ultra Low
Penetration Air (ULPA) filter sheet. The filter holder 18, wherein
the filter sheet 20 is arranged, may have a design as shown in FIG.
3B. It may consist of a plastic tube 22 showing an integrated
holder 24 for the filter sheet 20.
[0025] The first bag gets removed through pressure release by
cutting off the sealed end of the filter valve along line 26 (cf.
FIG. 1), thus allowing a controlled air stream into the second bag.
The filter secures that only particle free air is released from the
evacuated bag. The same procedure is used to open the inner bag. In
case also the inner bag is provided with the inventive valve, the
desired effect is increased.
[0026] The plastic tubing 8 in combination with the filter element
16, built into the bag 4, has the function of a valve filtering the
air from particles. The filter pore size determines the particle
limit filtered, which should satisfy regular class 1 clean room
conditions. After opening the weld-shut, the pressure release goes
fairly slow due to the filter resistance.
[0027] As has already been described above, in the old packaging
process, the FOSB is packed into two bags, one after the other, and
each bag gets evacuated to achieve shipment protection.
[0028] In the new, inventive method, the wafers are loaded into the
FOSB for transportation in the packaging area. The FOSB then gets
closed and is put into the first bag being provided with a filter
wave included in a corner portion of the bag. The bag then gets
evacuated to protect the box during shipment. For additional
protection a second bag is used that may also include the
filter-valve. The second bag is evacuated as well to additionally
protect the box during shipment.
[0029] FIGS. 4A and 4B depict flowcharts comparing the old (FIG.
4A) and the new (FIG. 4B) packaging process flow. The typical
problem is that after sorting from an FOSB into a Front Opening
Unified Pad (FOUP) at the customer's premises, at least the wafers
in the first and the last slot of the containers show increased
particle contamination. This is pretty much a common problem in
industry caused, as has already been explained, by the pressure
difference and the leaky seals of the boxes. The typical action to
resolve this problem up to now is that the wafers have to see wet
cleaning, which is an additional process step with remaining risk,
due to handling and treatment.
[0030] The controlled opening by cutting off the valves according
to the invention causes slow pressure release in the bag(s). This
prevents particles which are located on the outer bag's surface
from being sucked onto the inner bag or the FOSB surface,
respectively. From the box surface the particles reach into the box
through the seals, which, in the prior art, are not designed to
stay the rapid pressure difference. Thus, the controlled opening of
the bag(s), using the valves including a filter, has the positive
effect that the wet cleaning of the wafers can be eliminated.
[0031] The advantages of the inventive device and method are as
follows: [0032] No additional inspection, rework and further
cleaning required. [0033] Improvement of yield and substrate phase
in the process. [0034] Prevention of particle contamination,
triggered through bag opening, the filter pore size depending on
the cleanliness requirements. [0035] very simple application, only
air filters have to be added to the bag(s).
* * * * *