U.S. patent application number 10/905089 was filed with the patent office on 2006-06-08 for [semiconductor container that prevents crystalization on storage wafers/masks].
This patent application is currently assigned to GUDENG PRECISION INDUSTRIAL CO., LTD.. Invention is credited to MING-CHIEN CHIU, MING-LUNG CHIU, YU-CHIAN YAN.
Application Number | 20060120840 10/905089 |
Document ID | / |
Family ID | 36574402 |
Filed Date | 2006-06-08 |
United States Patent
Application |
20060120840 |
Kind Code |
A1 |
CHIU; MING-CHIEN ; et
al. |
June 8, 2006 |
[SEMICONDUCTOR CONTAINER THAT PREVENTS CRYSTALIZATION ON STORAGE
WAFERS/MASKS]
Abstract
A semiconductor container molded from a plastic material
containing silver that absorb sulfide to prevent crystal formation
on masks/wafers carried in the enclosed storage space inside the
semiconductor container during a photolithographic process under
the radiation of a deep-ultraviolet light source. In an alternate
form of the invention, the inside wall of the semiconductor
container is coated with a layer of silver to absorb sulfide. In
another alternate form of the present invention, blocks of silver
are fixedly provided inside the semiconductor container to absorb
sulfide in the enclosed storage space.
Inventors: |
CHIU; MING-CHIEN; (Taipei,
TW) ; CHIU; MING-LUNG; (Taipei, TW) ; YAN;
YU-CHIAN; (Taipei, TW) |
Correspondence
Address: |
GUDENG PRECISION INDUSTRIAL CO., LTD.
2F-4, NO. 148, SEC. 4, CHUNG HSIAO EAST ROAD
TAIPEI
TW
|
Assignee: |
GUDENG PRECISION INDUSTRIAL CO.,
LTD.
No. 428, Bade St., Shulin City,
Taipei Hsien
TW
|
Family ID: |
36574402 |
Appl. No.: |
10/905089 |
Filed: |
December 15, 2004 |
Current U.S.
Class: |
414/416.01 |
Current CPC
Class: |
G03F 1/66 20130101; G03F
7/70916 20130101; H01L 21/67366 20130101; G03F 1/64 20130101; H01L
21/67353 20130101 |
Class at
Publication: |
414/416.01 |
International
Class: |
B65B 69/00 20060101
B65B069/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 8, 2004 |
TW |
093134016 |
Claims
1. A semiconductor container made of a plastic material containing
power of silver that absorbs sulfide, preventing crystal formation
on storage masks/wafers in an enclosed storage space defined in the
semiconductor container during a photolithographic process under
the radiation of a deep-ultraviolet light source.
2. The semiconductor container as claimed in claim 1, which
comprises a container base, and a top cover covering said container
base and defining with said container base said enclosed storage
space.
3. The semiconductor container as claimed in claim 1, wherein said
plastic material is an anti-static plastic material.
4. A semiconductor container prevents crystal formation on storage
masks/wafers in an enclosed storage space defined in the
semiconductor container during a photolithographic process under
the radiation of a deep-ultraviolet light source, wherein the
semiconductor container has a silver coated on an inside wall
thereof for absorbing sulfide in said enclosed storage space.
5. The semiconductor container as claimed in claim 4, which
comprises a container base, and a top cover covering said container
base and defining with said container base said enclosed storage
space.
6. A semiconductor container that prevents crystal formation on
storage masks/wafers in an enclosed storage space defined in the
semiconductor container during a photolithographic process under
the radiation of a deep-ultraviolet light source, wherein the
semiconductor container comprising at least one block of silver
fixedly provided inside said enclosed storage space for absorbing
sulfide.
7. The semiconductor container as claimed in claim 6, which is made
of a material containing silver.
8. The semiconductor container as claimed in claim 6, which
comprises a container base, and a top cover covering said container
base and defining with said container base said enclosed storage
space.
Description
This application claims the priority benefit of Taiwan patent
application number 093134016 filed on Nov. 8, 2004.
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a semiconductor container
for carrying wafers/masks and more particularly, to such a
semiconductor container, which has silver directly added to the
material or coated on the inside wall of the semiconductor
container during fabrication of the semiconductor container, so
that silver absorbs sulfide, preventing crystal formation on
storage wafers/masks.
[0003] 2. Description of the Related Art
[0004] IC (Integrated Circuit) is one of the most important
elements that construct the so-called "third wave revolution" or
"information revolution". Computer, mobile phone, Internet, and LCD
are important inventions of this digital era that greatly influence
the living of human beings. Because IC chip has a wide application,
it is used in a variety of electronic consumer products including
computer and mobile phone. Following fast development of
semiconductor technology, electronic products are designed to meet
the requirements of modern electronic features such as light, thin,
short, small, high speed, high frequency, high performance, and
high precision. Heavy market demand for electronic products having
modern electronic features promotes development of semiconductor
technology towards this market trend. In consequence, investment in
semiconductor industry keeps increasing in recent years. Every
manufacturer is trying hard to create new technology in order to
take the leading place in the market so as to enjoy huge commercial
profit from the market. In order to survive from severe market
competition, it is important to reduce the cost and improve the
efficiency in this semiconductor field.
[0005] IC fabrication is an application of photolithography. This
technique is to have an electronic circuit pattern on a mask
reticle be projected onto a wafer by light. After developing and
baking, a contracted circuit pattern is formed on the wafer. The
wafer thus obtained is then processed through other posterior
procedures such as wafer saw, die attach, wire bond, molding, . . .
and etc. Therefore, reducing line width should be achieved by
improving photolithographic process. A relatively smaller
line-width CD value means a relative bigger number of transistors
in a unit area, and the IC will have a relative stronger function,
lower power consumption and lower cost. For example, when improved
the manufacturing process of a 128 MB DRAM from 0.25 .mu.m to 0.13
.mu.m, the productivity for 8 inches wafer will be increased by 4
times, or the number of dies will not be significantly reduced when
improved the production to 256 MB DRAM. This is the Moore's law
that is the observation made in 1965 by Intel co-founder Gordon
Moore that each new memory integrated circuit contained roughly
twice as much capacity as its predecesoor, and each chip was
released within 18-24 months of the previous chip.
[0006] Due to Moore's law, the successability of technical
improvement toward smaller line width CD value is determined
subject to photolithographic techniques, and scanner is the key
implement. Currently, 248 nm deep-UV is intensively used for 0.11
.mu.m photolithography. However, due to wavelength's sake, it is
not possible to have the downward going line be in the way like 90
nm.about.65 nm. Further, the use of 248 nm deep-UV for 0.11 .mu.m
lithography requires the so-called PSM (phase shift mask) reticle,
which is made of molybdenum (MO) that is about 2-3 times over the
price of chromium (Cr). In order to obtain a relatively smaller
line width, the wavelength of the exposure machine should be
relatively shorter. Therefore, 248 nm deep-ultraviolet light is
intensively used to substitute for 365 nm ultraviolet. Recently,
there are manufacturers studying the use of 193 nm deep-ultraviolet
photoresist and light source of ultra short wave (Argon fluoride
excimer laser to generate 193 nm deep-ultraviolet light) to improve
lithographic process to the stage of 0.13 .mu.m.about.65 nm.
[0007] However, current semiconductor manufacturers commonly use
SMIF system provided by Hewlett-packard for storing and
transporting wafers/masks, i.e., the so-called closed transfer
container. SMIF system is designed to reduce particle flux in
storage and transport of semiconductor products during a
semiconductor manufacturing process. This objective is achievable
by: keeping the air proximity to the wafer or mask from change
relative to the wafer or mask during storage and transport so as to
prevent passing of particles from the surroundings into the air
proximity to the wafer or mask. SMIF system uses a small amount of
particle-free air to provide a clean environment for the object
where the movement and flowing direction of the air and pollutant
are well controlled. This measure greatly reduces the cost for
clean room.
[0008] Before using 193 nm deep-UV to run a lithographic process,
as shown in FIG. 1, mask reticle A and mask pellicle B are stored
in an enclosed storage container D. When in use, mask reticle A and
mask pellicle B are taken out of the enclosed storage container D
and put in a mini-environment, and then radiated with 193 nm
deep-UV. At this time, harmful crystals C are formed on the surface
of mask reticle A and mask pellicle B (see FIG. 3). These crystals
C lower the transmittance of mask reticle A and mask pellicle B,
thereby resulting in distortion of the circuit pattern on mask
reticle A or low yielding rate. Sometimes, the whole lot of wafers
becomes unusable. This problem is indeed serious. This problem is
also seen in the old manufacturing process with 365 nm ultraviolet
light. However, because the old manufacturing process employs a
relatively longer wavelength that has a relatively lower energy to
provide a relatively lower capacity, the transparency of crystals
formed on wafers after radiation is still high enough, and the
problem of crystal formation on wafers during running of the old
manufacturing process is never so serious to obstruct the product.
According to experimentation, the transmittance of crystals formed
on wafers after radiation with 365 nm ultraviolet light T=76.1%;
the transmittance of crystals formed on wafers after radiation with
248 nm deep-UV T=29.2%, which is approximately the limit; the
transmittance of crystals formed on wafers after radiation with 193
nm deep-UV T=13%, which is about the opaque status. If this problem
is not settled, semiconductor manufacturing process will be limited
to 0.11 .mu.m, and the unit transistor capacity will not be doubled
as within 18 months as expected subject to Moore's law.
[0009] In order to eliminate the problem of the formation of
crystals on mask reticle A and mask pellicle B, the inventor of the
present invention studied the formation of harmful crystals C.
FIGS. 1 and 2 show a 193 nm deep-ultraviolet exposure bake process
according to the prior art. According to Example I in FIG. 2, mask
reticle A and mask pellicle B were kept in an enclosed storage
container D at 40.degree. C. for 3 days, and then mask reticle A
and mask pellicle B were taken out of the storage container D and
put in a mini-environment and radiated with 193 nm deep-UV, and
crystals were found on the surface of mask reticle A and mask
pellicle B. According to Example II in FIG. 2, mask reticle A was
put in an enclosed plastic storage container D at 40.degree. C. for
3 days, and then mask reticle A was taken out of the plastic
storage container D and put in a mini-environment and radiated with
193 nm deep-UV, and crystals were found on the surface of mask
reticle A. According to Example III in FIG. 2, mask reticle A and
mask pellicle B were put in an enclosed stainless steel storage
container D at 40.degree. C. for 3 days, and then mask reticle A
and mask pellicle B were taken out of the stainless steel storage
container D and put in a mini-environment and radiated with 193 nm
deep-UV, and no crystal C formation was seen on the surface of mask
reticle A and mask pellicle B. This study shows crystal formation
has a great concern with the storage container D.
[0010] According to study, we wound the reasons of crystal
formation as follows.
[0011] According to analysis, the chemical formula of the crystals
formed on mask reticle and mask pellicle is
(NH.sub.4).sub.2SO.sub.4, mainly composed of (NH.sub.4).sup.+ and
(SO.sub.4).sup.2-. During synthesis, there are important catalysts:
(a) light source of short wavelength high energy, (b) organic or
inorganic gas, (c) environment humility.
[0012] Either the use of KrF (Krypton fluoride) excimer laser to
generate 248 nm deep-ultraviolet light or ArF (Argon fluoride)
excimer laser to generate 193 nm deep-ultraviolet light, the narrow
pulse light has a high energy that is continuously supplied during
photolithography, which causes crystal formation upon its radiation
on mask. It shows that the shorter the wavelength is, the higher
the energy and the lower the transmittance of crystal will be.
[0013] Poor airtight status of the storage container allows passing
of wet air (water molecule) from the outside clean room into the
inside of the storage container to provide element requisite for
its chemical reaction, and therefore crystals are formed on the
surface of mask reticle and mask pellicle after removal from the
storage container and radiation with 193 nm deep-UV.
[0014] The material of the storage container itself releases
harmful gas that penetrates into the inside of mask pellicle,
thereby causing formation of crystals on mask reticle and mask
pellicle after removal from the storage container and radiation
with 193 nm deep-UV.
[0015] Because the aluminum frame of mask pellicle is made of
aluminum alloy treated with a sulfuric acid process, a big amount
of sulphate ion SO.sub.4.sup.2- is left on the surface of the
aluminum frame of mask pellicle, and the concentration of sulfur
molecule in the enclosed space inside the storage container will be
increased following evaporation of sulphate ion SO.sub.4.sup.2-,
thereby causing crystal formation on mask reticle and mask pellicle
after removal of mask reticle and mask pellicle from the storage
container and radiation of mask reticle and mask pellicle with 193
nm deep-UV.
SUMMARY OF THE INVENTION
[0016] The present invention has been accomplished under the
circumstances in view. It is therefore the main object of the
present invention to provide a semiconductor container, which
absorbs sulfide, preventing crystal formation on storage
wafers/masks. According to one embodiment of the present invention,
power of silver is directly added to plastics to form a
silver-contained plastic material for injection molding into the
designed semiconductor container such that power of silver in the
semiconductor container absorbs sulfide, preventing crystallization
on storage wafers/masks. According to an alternate form of the
present invention, the inside wall of the semiconductor container
is directly coated with a layer of silver that absorbs sulfide,
preventing crystallization on storage wafers/masks. According to
another alternate form of the present invention, blocks of silver
are fixedly provided inside the enclosed storage space of the
semiconductor container for absorbing sulfide to prevent crystal
formation on storage wafers/masks.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a schematic drawing showing a 193 nm
deep-ultraviolet exposure bake process according to the prior art
(I).
[0018] FIG. 2 is a schematic drawing showing a 193 nm
deep-ultraviolet exposure bake process according to the prior art
(II).
[0019] FIG. 3 is a schematic drawing showing crystal formation on a
photo mask.
[0020] FIG. 4 is a sectional view of a semiconductor container
according to one embodiment of the present invention.
[0021] FIG. 5 is a sectional view of an alternate form of the
semiconductor container according to the present invention.
[0022] FIG. 6 is a sectional view of another alternate form of the
semiconductor container according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0023] Referring to FIG. 4, a semiconductor container 1 in
accordance with the present invention is shown comprising a
container base 11, and a top cover 12 covering the container base
11 and defining with the container base 11 an enclosed storage
space 13.
[0024] According to conventional techniques, the container base 11
and the top cover 12 are respectively molded from plastics that are
high molecule polymers extracted from petroleum. However, plastic
material contains sulfide 2. After injection molding of the
container base 11 and the top cover 12, sulfide 2 will be
continuously evaporated from the container base 11 and the top
cover 12. According to the before-stated analysis, crystallized
compound contains a big percentage of sulfide. In order to
eliminate this problem, power of silver 3 is added to plastic
material to form a silver contained plastic material that is used
and injection-molded into the designed container base 11 and the
top cover 12. Thus, power of silver 3 in the container base 11 and
the top cover 12 absorbs sulfide 2 in the material, preventing
evaporation of sulfide 2 into the enclosed storage space 13, and
therefore the problem of crystallization on the surface of
wafers/masks is completely eliminated. Preferably, the plastic
material used is an anti-static plastic material.
[0025] FIG. 5 is a sectional view of an alternate form of the
semiconductor container according to the present invention.
According to this embodiment, the semiconductor container 1 is
constructed subject to SMIF (Standard Mechanical Interface)
definitions. In order to facilitate closing/opening of the top
cover 12, the locking force that locks the top cover 12 to the
container base 11 is limited. Further, because there is a
manufacturing tolerance from deformation, the airtight condition of
the enclosed will become worse with the use of the semiconductor
container 1, and external sulfide 2 will permeate into the enclosed
storage space 13 of the semiconductor container 1 gradually.
Therefore, the invention has the inside wall of the semiconductor
container 1 be coated with a layer of silver 3 that absorbs sulfide
2 in the enclosed storage space 13.
[0026] FIG. 6 is a sectional view of another alternate form of the
semiconductor container according to the present invention.
According to this embodiment, blocks of silver 3 are fixedly
provided in the enclosed storage space 13 inside the semiconductor
container 1 for absorbing sulfide 2.
[0027] Further, the semiconductor container 1 can be made of any of
a variety of materials containing silver 3.
[0028] As indicated above, the technical features of the present
invention to prevent crystallization on wafers/masks are as
follows.
[0029] 1. Power of silver can be added to plastics to form a
silver-contained plastic material for injection-molding into the
designed container base and top cover such that power of silver
power in the semiconductor container formed of the container base
and the top cover absorbs sulfide, preventing crystallization on
storage wafers/masks.
[0030] 2. The inside wall of the semiconductor container can be
directly coated with a layer of silver to absorb sulfide,
preventing crystallization on storage wafers/masks.
[0031] 3. Blocks of silver may be fixedly provided inside the
enclosed storage space of the semiconductor container to absorb
sulfide, preventing crystal formation on storage wafers/masks.
[0032] A prototype of semiconductor container has been constructed
with the features of FIGS. 4.about.6. The semiconductor container
functions smoothly to provide all of the features discussed
earlier.
[0033] Although particular embodiments of the invention have been
described in detail for purposes of illustration, various
modifications and enhancements may be made without departing from
the spirit and scope of the invention. Accordingly, the invention
is not to be limited except as by the appended claims.
* * * * *