U.S. patent application number 09/963385 was filed with the patent office on 2002-03-28 for method for manufacturing semiconductor device having low dielectric constant insulating film, wafer processing equipment and wafer storing box used in this method.
This patent application is currently assigned to KABUSHIKI KAISHA TOSHIBA. Invention is credited to Hasunuma, Masahiko, Kaneko, Hisashi, Miyajima, Hideshi, Nakata, Rempei.
Application Number | 20020037655 09/963385 |
Document ID | / |
Family ID | 18777582 |
Filed Date | 2002-03-28 |
United States Patent
Application |
20020037655 |
Kind Code |
A1 |
Hasunuma, Masahiko ; et
al. |
March 28, 2002 |
METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE HAVING LOW DIELECTRIC
CONSTANT INSULATING FILM, WAFER PROCESSING EQUIPMENT AND WAFER
STORING BOX USED IN THIS METHOD
Abstract
A method for manufacturing a semiconductor device, comprising
controlling a humidity in an atmosphere around a low dielectric
constant insulating film at 30% or less, during a processing period
and a transfer period between processing equipments, in which at
least a part of said low dielectric constant insulating film is
exposed to the atmosphere
Inventors: |
Hasunuma, Masahiko;
(Yokohama-shi, JP) ; Miyajima, Hideshi;
(Yokohama-shi, JP) ; Kaneko, Hisashi;
(Fujisawa-shi, JP) ; Nakata, Rempei;
(Kamakura-shi, JP) |
Correspondence
Address: |
Finnegan, Henderson, Farabow,
Garrett & Dunner, L.L.P.
1300 I Street, N.W.
Washington
DC
20005-3315
US
|
Assignee: |
KABUSHIKI KAISHA TOSHIBA
|
Family ID: |
18777582 |
Appl. No.: |
09/963385 |
Filed: |
September 27, 2001 |
Current U.S.
Class: |
438/778 ;
257/E21.576 |
Current CPC
Class: |
H01L 21/67017 20130101;
H01L 21/76828 20130101; H01L 21/67253 20130101 |
Class at
Publication: |
438/778 |
International
Class: |
H01L 021/31 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 27, 2000 |
JP |
P2000-295097 |
Claims
What is claimed is:
1. A method for manufacturing a semiconductor device, comprising:
controlling a humidity in an atmosphere around a low dielectric
constant insulating film at 30% or less during a processing period
and a transfer period between processing equipments in which at
least a part of said low dielectric constant insulating film is
exposed to the atmosphere.
2. The method of claim 1, wherein said processing period and said
transfer period includes: depositing said low dielectric constant
insulating film above a semiconductor wafer; first coating a whole
exposed surface of said low dielectric constant insulating film
with a metal film or an insulating film having a dielectric
constant more than 3.8; and a first transfer period during said low
dielectric constant insulating film is exposed between said
depositing and said first coating, wherein the humidity around the
semiconductor wafer is controlled at 30% or less during said
depositing, said first coating and said first transfer period.
3. The method of claim 2, wherein a temperature around the
semiconductor wafer is controlled at 75.degree. C. or more during
said depositing, said first coating and said first transfer
period.
4. The method of claim 2, wherein the humidity around the
semiconductor wafer is controlled at 25% or less and a temperature
around the semiconductor wafer is controlled at 23.degree. C. or
more during said depositing, said first coating and said first
transfer period.
5. The method of claim 2, wherein said processing period and said
transfer period further includes; exposing at least a part of said
low dielectric constant insulating film; second coating a whole
exposed surface of said low dielectric constant insulating film
with a metal film or an insulating film having a dielectric
constant more than 3.8; and a second transfer period during at
least a part of said low dielectric constant insulating film is
exposed between said exposing and said second coating, wherein the
humidity around the semiconductor wafer is controlled at 30% or
less during said exposing, said second coating and said second
transfer period.
6. The method of claim 5, wherein a temperature around the
semiconductor wafer is controlled at 75.degree. C. or more during
said depositing, said first coating, said first transfer period,
said exposing, said second coating and said second transfer
period.
7. The method of claim 5, wherein the humidity around the
semiconductor wafer is controlled at 25% or less and a temperature
around the semiconductor wafer is controlled at 23.degree. C. or
more during said depositing, said first coating, said first
transfer period, said exposing, said second coating and said second
transfer period.
8. The method of claim 1, wherein said low dielectric constant
insulating film has a dielectric constant of 3.8 or less.
9. The method of claim 8, wherein said low dielectric constant
insulating film contains silicon, oxygen and fluorine as its major
components.
10. The method of claim 8, wherein said low dielectric constant
insulating film contains a methyl group or an ethyl group, silicon
and oxygen as its major components.
11. A wafer processing equipment comprising: a wafer processing
chamber processing a semiconductor wafer by a predetermined
treatment to expose at least a part of a low dielectric constant
insulating film; a transfer tube connected to said wafer processing
chamber and through which the semiconductor wafer is carried into
and out from said wafer processing chamber; and a humidity control
unit controlling a humidity in said transfer tube at 30% or
less.
12. The wafer processing equipment of claim 11, further comprising
a temperature control unit controlling a temperature in said
transfer tube at 75.degree. C. or more.
13. The wafer processing equipment of claim 11, further comprising
a temperature control unit controlling a temperature in said
transfer tube at 23.degree. C. or more, wherein: said humidity
control unit controls the humidity in said transfer tube at 25% or
less.
14. The wafer processing equipment of claim 11, including: a
equipment depositing said low dielectric constant insulating film
above the semiconductor wafer; and a equipment coating a whole
exposed surface of said low dielectric constant insulating film
with a metal film or an insulating film having a dielectric
constant more than 3.8.
15. The wafer processing equipment of claim 11, wherein said
humidity control unit comprises a vacuum exhaust unit evacuating
inside of said transfer tube.
16. The wafer processing equipment of claim 11, wherein said
humidity control unit comprises an inert gas replacing unit
replacing an atmosphere in said transfer tube by inert gas.
17. A wafer storing box comprising: a wafer storing chamber storing
a semiconductor wafer provided with a low dielectric constant
insulating film, at least a pan of which is exposed; and a humidity
control unit controlling a humidity in said wafer storing chamber
at 30% or less.
18. The wafer storing box of claim 17, further comprising a
temperature control unit controlling a temperature in said wafer
storing chamber at 75.degree. C. or more.
19. The wafer storing box of claim 17, further comprising a
temperature control unit controlling a temperature in said wafer
storing chamber at 23.degree. C. or more, wherein: said humidity
control unit controls the humidity in said wafer storing chamber at
25% or less.
20. The wafer storing box of claim 17, wherein said humidity
control unit comprises a vacuum exhaust unit evacuating inside of
said wafer storing chamber.
21. The wafer storing box of claim 17, wherein said humidity
control unit comprises an inert gas replacing unit replacing an
atmosphere in said wafer storing chamber by inert gas.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method for manufacturing
a semiconductor device having a low dielectric constant insulating
film, to a wafer processing equipment depositing and exposing a low
dielectric constant insulating film, and to a wafer storing box
storing a semiconductor wafer during transfer between wafer
processing equipments. More particularly, the present invention
relates to a method for manufacturing a semiconductor device using
an interlayer insulating film, including the low dielectric
constant insulating film, which has weak properties as to the
peeling or cracks of a film and the like.
[0003] 2. Description of the Related Art
[0004] Along with a recent progress in highly integrated and
miniaturized semiconductor integrated circuits, a manufacturing
system for a semiconductor integrated circuit is usually disposed
in a clean room. The temperature of the clean room is controlled at
about 23.degree. C. under a relative humidity (RH) of about 40%
with the intention of removing dusts and static electricity, A
semiconductor wafer during the course of manufacture is exposed to
a clean room atmosphere, which is controlled in the above
temperature and humidity condition for a undefined period of time.
The undefined period of time includes during carrying-in and
carrying-out of the wafer from various wafer processing units and
during the transfer and storage between manufacturing stages
[0005] On the other hand, a recent progress in large-scaled and
high-speed semiconductor integrated circuits is accompanied by
progresses in multi-level of wiring and thin interlayer insulating
films. However, the decrease of the thickness of the thin
interlayer insulating film increases a parasitic capacitance
between wirings, which is an obstacle to a high-speed circuit
operation. In order to decrease the parasitic capacitance between
wirings, a low dielectric constant insulating film, known as "low
k" film is required as the interlayer insulating film. As the low k
dielectric film may include a silicon oxide (SiO.sub.2) film
containing an organic component (hereinafter referred to as "LKD"
film) and a fluorinated silicon oxide film (SiOF film). The SiOF
film is generally called "FSG film (Fluorinated Silica Glass
film)". The SiOF film is reduced in dielectric constant by adding
fluorine to silicon oxide (SiO.sub.2). Multi-level wiring
technologies using these low dielectric constant insulating films
as the interlayer insulating films are commonly used.
BRIEF SUMMARY OF THE INVENTION
[0006] An aspect of the present invention inheres in a method for
manufacturing a semiconductor device comprising controlling a
humidity in an atmosphere around a low dielectric constant
insulating film at 30% or less during a processing period and a
transfer period between processing equipments in which at least a
part of the low dielectric constant insulating film is exposed to
the atmosphere.
[0007] Another aspect of the present invention inheres in a wafer
processing equipment comprising a wafer processing chamber which
provides a semiconductor wafer with a predetermined treatment, a
transfer tube which is connected to the wafer processing chamber
and through which the wafer is carried into and out from the wafer
processing chamber, and a humidity control unit which controls the
humidity of the transfer tube at 30% or less.
[0008] Still another aspect of the present invention inheres in a
wafer storing box comprising a wafer storing chamber which stores a
semiconductor wafer on which a low dielectric constant insulating
film is deposited, and a humidity control unit which controls the
humidity of the wafer storing chamber at 30% or less.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0009] FIG. 1A is a plan view showing a scratch formed on the
surface of an LKD fib film having a film thickness of 900 nm.
[0010] FIG. 1B is a plan view showing a scratch formed on the
surface of an LKD film having a film thickness of 983 nm.
[0011] FIG. 2 is a graph showing the relationship between the rate
of the progress of cracks of an LKD film in a clean room atmosphere
and the film thickness of the LKD film.
[0012] FIG. 3 is a table showing storing temperature and humidity
in a storing box and the value of maximum film thickness of an LKD
film when no cracks occurs.
[0013] FIG. 4 is a graph showing the relationship between the
concentration of fluorine (F) in an SiOF film used as a low
dielectric interlayer insulating film and water content (that is,
the amount of the adsorbed moisture) contained in the SiOF film
after the film is allowed to stand for one week in a normal clean
room atmosphere after it is deposited.
[0014] FIG. 5 is a graph showing the relationship between the
concentration of F in a SiOF film and percent failures ascribable
to the SiOF film during the course of a method for manufacturing a
semiconductor device in a normal clean room atmosphere.
[0015] FIG. 6 is a graph showing the relationship between the
concentration of F in a SiOF film and percent failures ascribable
to the SiOF film when the temperature of the atmosphere around a
semiconductor wafer is fixed at room temperature (RT) and the
humidity of the atmosphere is changed.
[0016] FIG. 7 is a graph showing the relationship between the
concentration of F in a SiOF film and percent failures ascribable
to the SiOF film when the relative humidity (RH) of the atmosphere
around a semiconductor wafer is fixed to 30% and the temperature of
the atmosphere is changed.
[0017] FIG. 8 is a graph showing the relationship between the
dielectric constant and percentage failures of various low
dielectric constant insulating films.
[0018] FIG. 9 is a block diagram showing the structures of a wafer
processing tV equipment and a wafer storing box according to a
first embodiment of the present invention.
[0019] FIG. 10 is a flowchart showing a method for manufacturing a
semiconductor device according to the first embodiment of the
present invention.
[0020] FIG. 11 is a block diagram showing the structures of a wafer
processing equipment and a wafer storing box according to a second
embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0021] Various embodiments of the present invention will be
described with reference to the accompanying drawings. It is to be
noted that the same or similar reference numerals are applied to
the same or similar parts and elements throughout the drawings, and
the description of the same or similar parts and elements will be
omitted or simplified.
[0022] First Experimental Example
[0023] Low dielectric constant insulating films generally have a
low Young's modulus and hence low breaking toughness correlated
with the Young's modulus. Therefore, the low dielectric constant
insulating films involve the problem as follows. Cracks
(self-cracks) occur in a self-breaking manner if the low dielectric
constant insulating films are thickened. Cracks is made to progress
by chemical mechanical polishing (CMP), and by scratches caused
during the course of manufacture, for example, during the course of
the transfer of a wafer
[0024] It has been clarified from our studies as follows. In the
vicinity of a metal wiring in which Young's modulus and linear
expansion coefficient differ from the low dielectric constant
insulating film, the thermal stress in manufacturing process is
concentrated. In spite of being thinner than the limitative film
thickness that causes the self crack in the solid states, the self
crack is generated in the low dielectric constant insulating film,
and this self crack progresses.
[0025] This concentration of stress disturbs the formation of a
thick interlayer insulating film. The progress of cracks causes
vital defects such as wiring failures, for example, the short
circuits between wirings in the same level and between vertically
stacked levels.
[0026] Moreover, the low dielectric constant insulating films
generally have high hygroscopicity and gas permeability. Even if
the low dielectric constant insulating film is exposed to the above
clean room atmosphere only for a very short time, it adsorbs
moisture, and gas is left resultantly. Particularly, if the SiOF
film has adsorbed the moisture once, it will releases the water
when heated. Also this water reacts with fluorine contained in the
SiOF film, to release fluorine (F) in the form of hydrogen fluoride
(HF). It is known that this causes the following hindrances
resultantly.
[0027] (1) The formation of an upper level film is inhibited, when
the upper level film is formed on the low dielectric constant
insulating film.
[0028] (2) The adhesion of the upper level film, particularly an
upper level metal film is deteriorated.
[0029] (3) The dielectric constant of the LKD film is raised.
[0030] (4) Resistance to cracks is deteriorated.
[0031] These hindrances become serious problems in the
manufacturing of semiconductor devices using the low dielectric
constant insulating film. For this, a semiconductor device is
frequently heated to remove water. Or the SiOF film is coated with
a SiO.sub.2 film (cap film), to which no fluorine is added, to
prevent the SiOF film from being exposed, thereby avoiding the
above hindrances.
[0032] However, because a process of removing water or a process of
applying the cap film are added, the number of processes is
increased, leading to increased costs. It is not said to take
sufficient measures for solving the problems concerning the
moisture absorption and the residual gas, only by the frequent
heating treatments and the use of the cap film, For example, the
SiOF film adsorbs moisture in a short period of time, until the cap
film is formed since the SiOF film is formed. Even if after the
SiOF film is formed, the SiOF film is not allowed to stand in the
atmosphere. The cap film is successively formed in the same
equipment. A part of the SiOF film is exposed again when the
surface of the cap film is processed utilizing a dry etching
process and a CMP process. As a result, SiOF film adsorbs moisture
from the exposed portion at a period between the cap film
processing stage and the next stage. Therefore, the above
hindrances (1) to (4) cause the defects of semiconductor devices.
It is desired to take prompt measures to solve these problems.
[0033] The present inventors have discovered from the results of
these studies as follows. The above hindrances are caused by the
fact, that a Si--O bond (bond between silicon and oxygen) of the
low dielectric constant insulating film becomes easy to be cut by
Stress Corrosion Cracking (SCC). Particularly, a Si--O bond,
connecting between ladder structures, is weak in the case of a
SiO.sub.2 film containing an organic component.
[0034] Then, the inventors considered that the above defects can be
limited by removing water and stress which are the causes of these
defects. Then, various experiments as will be explained later have
conducted, to complete the present invention based on the results
of these experiments.
[0035] Examples of the experiments conducted by present inventor
will be explained, prior to explanations of the embodiments of the
present invention.
[0036] When an LKD film increased in thickness is exposed to a
clean room atmosphere, cracks occur in a self-breaking manner
(self-crack). The critical film thickness allowing this self-crack
to occur is about 1.5 .mu.m though it varies depending on the kind
of film.
[0037] Moreover, it has been confirmed for the first time as
follows. Even if an LKD film is made thin to the extent, cracks
propagates at a rate corresponding to the film thickness by
scratching the surface of the LKD film. In the above extent, no
crack occurs in the condition that it is exposed to a natural
atmospheric ambient.
[0038] Further, it has been confirmed as follows. When a metal
wiring is arranged in the vicinity of the LKD film, thermal stress
is concentrated on the LKD film close It to the metal wiring. The
metal wiring is different in Young's modulus and linear expansion
coefficient from the LKD film. Therefore self-cracks occur even if
the thickness is less than the critical film thickness, which
define the thickness to allow the self-cracking. The propagation of
cracks of the scratched portion is accelerated.
[0039] Further, it has been confirmed as follows. The presence of
such cracks causes fatal defects such as the development of short
circuits of wirings, when current is applied.
[0040] FIGS. 1A and 1B are plan views respectively showing the
shapes of the scratches formed on the surfaces of the LKD films.
FIG. 1A shows the case where the film thickness of the LKD film is
900 nm. FIG. 1B show the case where the film thickness of the LKD
film is 983 nm.
[0041] Two samples of FIG. 1A are formed, which have the LKD films
with film thickness of 900 nm on the thermal oxide films having
thickness of 100 nm, which are formed on Si substrates. Another two
samples of FIG. 1B are formed, which have the LKD films with
thickness of 983 nm on the thermal oxide films. These samples were
scratched as shown in FIG. 1A and FIG. 1B, and exposed to the
atmospheric ambient, which is controlled at room temperature
(23.degree. C.) under a humidity of 25% for 35 days. Moreover, the
still another samples, having the same film structures and provided
with scratches, were exposed to the atmospheric ambient, controlled
at 75.degree. C. under a humidity of 30% for 35 days. As a result,
any propagation of cracks was not found in all samples.
[0042] FIG. 2 is a graph showing the relationship between the rate
of the propagation in the cracks of the LKD film in a clean room
atmosphere and the film thickness of the LKD film. As shown in FIG.
2, in the case of exposing the sample to the clean room atmosphere,
controlled at the humidity of 40% and the temperature of 23.degree.
C., cracks of the sample with the film thickness of 900 nm
propagated at a rate of 1.5 .mu.m/hr Cracks of the sample with the
film thickness of 983 nm propagated at a rate of 17 .mu.m/hr. Both
samples resulted in peeling of the film, finally. It was also found
from similar experiments in other conditions, that the logarithm of
the rate of the propagation of cracks increased in proportion to
the film thickness of the LKD film, as shown in FIG. 2.
[0043] Moreover, the humidity and the temperature were changed. As
a result, no propagation of cracks was observed by controlling the
humidity at 30% or less when the temperature was controlled at
75.degree. C. And also, no propagation of cracks was observed by
controlling the humidity at 25% or less when the temperature was
controlled to be at 23.degree. C. It is to be noted that even if
the sample was exposed to high humidity for a short time, there was
no problem.
[0044] Next, boron-phosphate-silicate-glass (BPSG) and further
d-Tetraethoxysilane (TEOS) were laminated above a Si substrate, on
which an active region and a gate electrode were formed. Then, a
tungsten (W) plug was formed. Five LKD films, having thicknesses of
1 .mu.m, 1.5 .mu.m, 2 .mu.m, 2.5 .mu.m and 3 .mu.m as final
thicknesses after baked, were formed. The method of forming the LKD
film and the experimental method are as follows.
[0045] First, varnish obtained by dissolving polymethylsiloxane in
a solvent, was applied by a spin coater. Thereafter, the varnish
was cured at 80.degree. C. for one minute. In succession, the
varnish was cured at 200 .degree. C. for one minute. Further the
varnish was baked at 450.degree. C. for 30 minutes. The humidity in
this course is due to water generated during baking. The flow rate
of nitrogen gas was controlled, such that the humidity in this
course was lower than the storing humidity shown in FIG. 3. After
it) baked, when the temperature of the substrate was dropped to
each temperature shown in FIG. 3, the sample was allowed to pass
through a transfer chamber. Then the sample was allowed to transfer
to a storing box, which is controlled at each storing temperature
and humidity shown in FIG. 3. After the sample was stored in the
storing box for 30 days, it was confirmed whether cracks were
present. The sample was irradiated with intense light. The
evaluation of resistance to cracks was made by a whether or not
scattered light was observed using an optical microscope. The value
of the maximum film thickness, at which the generation of cracks
was not found, is described together in FIG. 3.
[0046] Films of d-TEOS/p-SiN were formed in thickness of 400 nm/400
nm respectively, on the upper level of the sample transferred in
the atmosphere of FIG. 3. Then the sample was stored in an
atmosphere controlled at 23.degree. C. and a humidity of 40% for 30
days. The sample was measured whether or not cracks were present.
As a result, the same results as those shown in FIG. 3 were
obtained.
[0047] From the above results, besides it was dependent on the film
thickness that the propagation of cracks from the scratch and
self-cracks caused by the formation of a thick film, the following
three points were newly confirmed.
[0048] (1) Humidity dependency: if the humidity during storage was
changed, the higher the humidity was, the higher the propagation
rate of cracks was. And also the higher the humidity was, the
thinner the critical film thickness at which the propagation of
self-cracks started was. In an extreme case where the sample was
exposed to water, such tendency became more significant. On the
contrary, if the humidity was decreased, a quite inverse tendency
was exhibited. If the humidity was controlled at 25% or less, it
was possible to stop the propagation of cracks from the scratch.
Moreover, the humidity in whole process, including water generated
when the LKD film was condensed, was controlled at 25% or less. As
a result, the critical film thickness of spontaneous cracks could
be made very large. The above results to were very significant when
the humidity was 25%, but rather good even if the humidity was 30%
or less.
[0049] (2) Temperature dependency: Moreover, when the sample was
stored in a manner that the temperature of the LKD film was not
dropped to 75.degree. C. or less by heating, any propagation of
cracks was nor observed at all. The critical film thickness of the
self-cracks, caused by the formation of a thick film, can be made
high.
[0050] (3) Stress dependency: When tensile stress was further
applied to the LKD film with the scratch, by using a four-point
bending tester, the propagation rate of cracks was accelerated. It
was clarified form the results of measurement of film stress, that
stress applied to the film was relaxed, by controlling the samples
at higher temperatures.
[0051] Second Experimental Example
[0052] FIG. 4 is a graph showing the relationship between the
concentration of fluorine (F) in an SiOF film, used as a low
dielectric constant insulating film, and water content (that is,
the amount of the adsorbed moisture) contained in the SiOF film.
The SiOF film has been exposed for one week to a clean room
atmosphere. The clean room atmosphere is controlled at a related
humidity (RH) of 40% and the room temperature (RT) of 23.degree. C.
The SiOF film was deposited by using a high density plasma CVD
apparatus of Applied Materials, Inc. As the source gas for CVD,
mixture gas of SiFH.sub.4/SiF.sub.4/O.sub.2/Ar was used here.
Moreover, the evaluation for the amount of adsorbed moisture was
made by analyzing the SiOF film having thickness of 500 nm. The
analysis of the SiOF film was done by using a Fourier Transfer
Infrared (FT-IR) analyzer. The amount of adsorbed moisture is
expressed by the ratio of the sum of the Si--OH peak and the H--OH
peak, which are observed in the vicinity of 3500 cm.sup.-1, to the
area of the Si--O peak observed in the vicinity of 1100
cm.sup.-1.
[0053] With the originality and ingenuity of the present inventors,
the condition, under which the SiOF film is formed, is regulated so
that the adsorbed moisture after exposed to the atmosphere can be
limited to a low level.
[0054] However, as is clear from FIG. 4, it is understood that the
amount of adsorbed moisture after one week exposure increases, as
the concentration of F in the film increases. Particularly, it is
understood that the amount of adsorbed moisture increases rapidly,
surmounting the borderline where the concentration of fluorine in
the film becomes 10%.
[0055] FIG. 5 is a graph showing the relationship between the
concentration of F in the SiOF film and percent failures, The
failures ascribable to the SiOF film, formed during the course of
manufacturing a semiconductor device in a normal clean room
atmosphere. "The failures ascribable to the SiOF film" are caused
not only by the released water during beating in the subsequent
stage, but also by releasing HF, after the reactions of moisture
with F in the SiOF film. The failures ascribable to the SiOF film
generate the following disadvantages. (1) The deposition of the
film is inhibited when a film of the upper level is formed. (2) The
adhesion of an upper level film, particularly, an upper level metal
film is deteriorated. (3) the dielectric constant of the SiOF film
is increased. As is clear from FIG. 4 and FIG. 5; it is understood
that the amount of moisture adsorbed by the SiOF film after one
week exposure is closely related to the percentage failures
ascribable to the SiOF film.
[0056] FIG. 6 is a graph showing the relationship between the
concentration of F in the SiOF film and percent failures ascribable
to the SiOF film. In FIG. 6, the temperature of the atmosphere
around a semiconductor wafer is fixed to room temperature (RT), and
the humidity of the atmosphere is changed. FIG. 7 is a graph
showing the relationship between the concentration of F in the SiOF
film and percent failures ascribable to the SiOF film. In FIG. 7,
the related humidity (RH) of the atmosphere around a semiconductor
wafer is fixed to 30%, and the temperature of the atmosphere is
changed. As is clear from FIG. 6, the percent failures ascribable
to the SiOF can be limited to a low level, regardless of the
concentration of fluorine, by controlling the related humidity (RH)
at 30% or less at room temperature. As is clear from FIG. 7, it is
understood that controlling the temperature at 75.degree. C. or
more, when the humidity is 30%, further increases the effect of
suppressing the percent failures to a low level.
[0057] Third Experimental Example
[0058] The dielectric constant of the "low dielectric constant
insulating film" in the embodiment of the present invention, is
defined based on experimental examples shown below, A thermal oxide
film with a thickness of 100 nm was formed on a silicon substrate.
Various low dielectric constant insulating films were formed in a
thickness of 1 .mu.m. Thereafter, the following three treatments
were carried out, in order to measure the percent failures. The
measurement of the percent failures is based on whether or not the
cracks of these various low dielectric constant insulating films
were present. And also the measurement of the percent failures is
based on whether or not the tantalum (Ta) film was peeled off.
[0059] (1) The silicon substrate was exposed to an atmosphere
controlled at a humidity of 40% and a temperature 23.degree. C.
After that, it was confirmed whether or not cracks were
present.
[0060] (2) A scratch was formed. Then the silicon substrate was
exposed to an atmosphere controlled at a humidity of 40% and a
temperature 23.degree. C. for one week. After that, it was
confirmed whether or not cracks were present.
[0061] (3) The substrate was exposed to an atmosphere controlled at
a humidity of 40% and a temperature of 23.degree. C. After that, a
Ta film was formed. Then, the substrate was subjected to heat
treatment at 400.degree. C. Thereafter, it was confirmed whether or
not the Ta film was peeled off.
[0062] FIG. 8 is a graph showing the relationship between the
dielectric constant and percentage failure of various low
dielectric constant insulating films. As shown in FIG. 8, it was
found that failures occur frequently when the dielectric constant
was 3.8 or less. The value of the percentage failures depends on
the material quality of the low dielectric constant insulating
film. From these experimental results, insulating films having a
dielectric constant of 3.8 or less, is defined as the "low
dielectric constant insulating film" in the embodiment of the
present invention.
[0063] Here, the low dielectric constant insulating film includes
the LKD film and the SiOF film. The low dielectric constant
insulating film includes the insulating film, in which a
propagation of the cracks is much accelerated. The low dielectric
constant insulating film includes the insulating film having the
low Young's modulus. "The LKD film" is a SiO.sub.2 film containing
an organic component. The LKD film is manufactured as follows. A
liquid raw material, called varnish, is coated on the substrate,
and sintered. The following are carried out: the volatilization of
a solvent and cross-link (polymerization reaction) of the
precursor. The SiO.sub.2 film containing an organic component is
characterized by the inclusion of a methyl group (--CH.sub.3) or an
ethyl group (--C.sub.2H.sub.5) in atomic bonds. Moreover, the low
dielectric constant insulating film contains the inorganic coating
film, comprising an inorganic material such as
hydrogensilsesquioxane. And also, the low dielectric constant
insulating film contains an organic coating film, comprising an
organic material such as polyallylene ether.
[0064] From the above experimental result, the followings are
confirmed, The generation or the propagation of the crack of the
low dielectric constant insulating film can be suppressed, by
controlling the atmospheric ambient around the semiconductor wafer.
The atmospheric ambient, to which at least the part of the low
dielectric constant insulating film is exposed, must be controlled
to be 30% humidity or less. It is to be noted that the same effect
can be obtained, also by controlling the temperature of the
atmospheric ambient around the low dielectric constant insulating
film to be at 75.degree. C. or more, instead of controlling the
humidity. In a method for manufacturing a semiconductor device
according to the embodiment of the present invention, "a processing
period in which at least a part of a low dielectric constant
insulating film is exposed" may include: depositing the low
dielectric constant insulating film; exposing at least a part of
the low dielectric constant insulating film; coating all of the
exposed part with a metal film or with an insulating film having a
dielectric constant of more than 3.8; and all wafer processing
period performed during these actions. Further, the period "a
transfer period between processing equipments" includes, the period
required to transfer a semiconductor wafer during the course of
manufacture between respective wafer processing equipments used in
these wafer processing stages; and the period required to store the
semiconductor wafer during the course of manufacture.
[0065] First Embodiment
[0066] Hereinafter, the first embodiment of the present invention
will be explained with reference to the drawings, FIG. 9 is a block
diagram showing the Structures of a wafer processing equipment 1
and a wafer storing box 3, according to the first embodiment. As
shown in FIG. 9, the wafer processing equipment 1 encompasses a
wafer processing chamber 2, a transfer tube 4 which is connected to
the wafer processing chamber 2, a humidity control unit 6 which
controls the humidity at 30% or less under control in the transfer
tube 4, and a temperature control unit 5 which controls the
temperature at 75.degree. C. or more in the transfer tube 4. The
semiconductor wafer is carried into and out from the wafer
processing chamber 2 through the transfer tube 4.
[0067] The wafer processing equipment 1 may be one of various
apparatuses used in manufacturing stages, in which at least a part
of the low dielectric constant insulating film (for example, the
LKD film) is exposed to a clean room atmosphere. For example, the
apparatuses may be the LKD film deposition apparatus, a TEOS film
deposition apparatus, a reactive ion etching (RIE) apparatus, and a
metal film deposition apparatus. The LKD film deposition apparatus
deposits an LKD film on the semiconductor wafer. The TEOS film
deposition apparatus deposits on the whole exposed surface of the
LKD film, a TEOS film as an ordinary insulating film. The RIE
apparatus digs the holes and grooves such that a part of the LKD
films are exposed on the sidewalls by selectively removing the TEOS
film and the LKD film. The metal film deposition apparatus deposits
on the whole exposed portion of the LKD film a metal film, the
metal film covers on the hole, the groove and the TEOS film. The
wafer processing equipment 1 involves, besides the above
apparatuses, another apparatus exposing at least a part of the LKD
film by, such as, a flattening machine employed in the CMP process,
and a washing equipment cleaning the surface of the wafers between
exposing the LKD film and the coating LKD film. In short, the wafer
processing equipment 1, in the first embodiment, includes all of
the apparatuses associated with depositing the low dielectric
constant insulating film, exposing at least a part of the low
dielectric constant insulating film, coating the whole of the
exposed part, and another wafer processes performed between these
executions.
[0068] The atmosphere surrounding the semiconductor wafer in the
wafer processing chamber 2 is controlled at a humidity of 30% or
less and a temperature of 75.degree. C. or more. The transfer tube
4 is integrated with the wafer processing chamber 2, integrated
with the wafer storing box 3, and formed in a detachable manner
through a flange. In the transfer tube 4, a movable carrier (not
shown) is disposed. The movable carrier carries the semiconductor
wafer in and out from the wafer processing chamber 2. The humidity
control unit 6 desirably controls the humidity at 25% or less in
the transfer tube 4. For preventing dielectric breakdown or device
destruction by the static electricity, it is desirable that the
humidity control unit 6 has an ion generation apparatus. By having
the ion generation apparatus, it is possible to perfectly suppress
the generation of the trouble by the electrostatic destruction.
[0069] The wafer storing box 3 protects the semiconductor wafer
from the external atmosphere, when transferring the semiconductor
wafer between the wafer processing chamber 2 and the wafer storing
box 3 in each of the processing equipments 1. Moreover, the wafer
storing box 3 controls the atmosphere around semiconductor wafers
when the semiconductor wafers, in which at least a pan of a low
dielectric constant insulating film are exposed, are stored, The
wafer storing box 3 encompasses a wafer storing chamber 7, a
humidity control unit 9, and a temperature control unit 8. The
wafer storing chamber 7 stores the semiconductor wafer, on which
the low dielectric constant insulating film is deposited. The
humidity control unit 9 controls the humidity in the wafer storing
chamber 7 at 30% or less. The temperature control unit 8 controls
the temperature in the wafer storing chamber 7 at 75.degree. C. or
more. The wafer storing chamber 7 has a size and shape enough to
store one or plural semiconductor wafers 10. The semiconductor
wafers 10 stored in the wafer storing chamber 7 are aligned,
standing at each edges.
[0070] The wafer storing box 3 is further provided with a door 24,
The door 24 is opened and closed in close contact with an
inlet/outlet port of the transfer tube 4. The size of the door 24
is adjustable to the size of the inlet/outlet port of the transfer
tube 4. Further, the height of the door 24 is adjustable to the
height of the inlet/out port of the transfer tube 4. This makes it
possible to carry semiconductor wafers in and out from respective
wafer processing equipments 1 by using one wafer storing box 3,
even if the sizes of the ports are different for the every
equipments 1. In the condition that the humidity and temperature
around the semiconductor wafers are controlled, the wafers can be
carried in and out the respective wafer processing equipments 1 and
the wafer storing box 3 through the door 24. The humidity control
unit 9 desirably controls the humidity in the wafer storing chamber
7 at 25% or less. For preventing dielectric breakdown or device
destruction by the static electricity, it is desirable that the
humidity control unit 9 has an ion generation apparatus. By having
the ion generation apparatus, it is possible to perfectly suppress
the generation of the trouble by the electrostatic destruction.
[0071] A method for manufacturing a semiconductor device, according
to the first embodiment of the present invention, will be explained
with reference to FIG. 10. The manufacturing method uses the wafer
processing equipment 1 and the wafer storing box 3, shown in FIG.
9. The manufacturing method shown by the flowchart of FIG. 10
involves the first to the fourth processes. The center line of the
flowchart shows wafer processing chambers (2A to 2D) and transfer
tubes (4A to 4D) relating to each process. The broad right line on
the right side of the flowchart shows the wafer storing boxs 3 for
transferring the semiconductor wafer between each wafer processing
equipment (2A to 2D). On the left side of the flowchart, the cross
sectional views corresponding to the respective processes are
arranged vertically.
[0072] (a) At first, the low dielectric constant insulating film
(for example, LKD film) 17 with a film thickness of 1.5 .mu.m is
deposited above a semiconductor wafer (base substrate), by using
first wafer processing equipment (spin coater) 1A. The
predetermined substrate treatment stages are carried out, before a
LKD film is deposited. The predetermined substrate treatment stages
including the formations of element isolation regions, transistors,
gate wirings, BPSG 16, and W plug 30. More specifically, the
semiconductor wafer, secured to a sample table in a spin coating
chamber 2A, is rotated. A liquid source material for a low
dielectric constant insulating (for example, LKD film) 17 is
applied to the semiconductor wafer. The liquid source material is
cured in a nitrogen atmosphere, having a humidity of 30% or less.
In succession to the low temperature curing, the wafer is baked at
450.degree. C. for 60 minutes. After the LKD film 17 is deposited
on the BPSG 16, the surface 18 of the LKD film is exposed to an
atmosphere in the spin coating chamber 2A. The atmosphere of the
spin coating chamber 2A, after the LKD film 17 is deposited, is
controlled at a humidity of 30% or less and a temperature of
75.degree. C. or more. After baked, the temperature of the
substrate is dropped to 75.degree. C. At the same time, the
atmosphere of the transfer tube 4A is controlled at a humidity of
30% or less and a temperature of 75.degree. C. or more. Then, the
semiconductor wafer, in which the LKD film 17 is exposed, is
carried out to the transfer tube 4A. The semiconductor wafer is
transferred to the wafer storing box 3, by allowing the
semiconductor wafer to pass through the transfer tube 4A. The wafer
storing box 3 have controlled at a humidity of 30% and a
temperature of 75.degree. C. The semiconductor wafers are aligned
standing at each edges in the wafer storing box 3 so that no stress
is applied. In this manner, the semiconductor wafer is conveyed
from the spin coating chamber 2A to the wafer storing box 3, in the
condition that the atmosphere around the semiconductor wafer,
provided with the exposed LKD film 17, is controlled at a humidity
of 30% or less and a temperature of 75.degree. C. or more.
[0073] (b) Next, the semiconductor wafers, provided with the
exposed LKD film 17, are transferred from the spin coating
apparatus (first wafer processing equipment) 1A to another wafer
processing equipment (the second wafer processing equipment) 1B, by
using the wafer storing box 3. During transfer 13 (first transfer
period) between the first processing equipment 1A to the second
processing equipment 1B, the atmosphere around the semiconductor
wafer, stored in the wafer storing box 3, is controlled at a
humidity of 30% or less and a temperature of 75.degree. C. or more.
By using the humidity control unit 9 and the temperature control
unit 8, the above atmosphere around the semiconductor wafer is
achieved.
[0074] (c) Then, a TEOS film 19 is deposited using the second wafer
processing equipment (TEOS film deposition apparatus) 1B. The
entire exposed surface 18 of the LKD film 17 is coated with the
TEOS film 19. To sate in detail, the door 24 of the storing box 3
is brought into close contact with the inlet port of a transfer
tube 4B of the TEOS film deposition apparatus 1B. The door 24 of
the storing box 3 is opened in the condition, that the atmosphere
in the transfer tube 4B is controlled at a humidity of 30% or less
and a temperature of 75.degree. C. or more. By using the humidity
control unit 6 and the temperature control unit 5, the above
atmosphere in the transfer tube 41B is achieved. Then, the
semiconductor wafers, provided with the exposed LKD film 17, are
transferred to the transfer tube 4B. The semiconductor wafers are
carried into a TEOS film deposition chamber 2B through the transfer
tube 4B. The semiconductor wafers are placed on a sample table.
Then, the TEOS film deposition apparatus 1B is allowed to operate
to deposit a TEOS film 19, having a predetermined thickness. The
TEOS film 19 coats the whole exposed surface 18 of the Lo film 17.
After the TEOS film 19 was deposited, the semiconductor wafers are
carried out from the TEOS film deposition chamber 2B to the storing
box 3 through the transfer tube 4B. At this time, since the LKD
film 17 on the semiconductor wafer is not exposed, the atmosphere
around the semiconductor wafer may be a normal clean room
atmosphere without any problem. It is to be noted that after the
TEOS film 19 was deposited, one of the semiconductor wafers was
sampled to observe the surface states of the semiconductor wafers.
As a result, the occurrence and progress or propagation of cracks
were not observed on the sampled semiconductor wafer. It was,
therefore, found that resistance to cracks was high.
[0075] (d) Then, the semiconductor wafer is scheduled to be
transferred from the TEOS film deposition apparatus (the second
wafer processing equipment) 1B to the third wafer processing
equipment 1C, by using the wafer storing box 3. However, prior to
the third wafer processing equipment 1C, the semiconductor wafers
are a lithographic process, including photo resist coating,
exposure, development, lines, post bake, etc. Since the LKD film 17
on the semiconductor wafer is not exposed in the lithographic
process during the transfer 14 between the second wafer processing
equipment 1B and the third wafer processing equipment 1C. The
atmosphere of the lithographic process around the semiconductor
wafers may be a normal clean room atmosphere without any
problem.
[0076] (e) After the lithographic process is carried out, the
semiconductor wafers, coated with the delineated photo resist
pattern, are stored in the storing box 3. And the storing box 3 is
transferred to the inlet port of the third wafer processing
equipment 1C. And a part of the TEOS film 19 and LKD film 17 is
selectively removed using the third wafer processing equipment (RIE
apparatus) 1C. The RIE apparatus 1C digs a damascene wiring groove
20, and a part of the LKD film 17 is exposed at the sidewall of the
damascene wiring groove, To state in detail, the door 24 of the
storing box 3 is opened to take out the semiconductor wafers. The
semiconductor wafers are allowed to pass through the transfer tube
4C of the RIE apparatus 1C. Each of the semiconductor wafers is
placed on a sample table in the RIE chamber 2C. Then, the RIE
apparatus 1C is allowed to carry out predetermined anisotropic
etching treatment. The RIE apparatus 1C selectively removes the
TEOS film 19 and the LKD film 17 in the window parts defined by the
delineated photo resist film, to form the damascene wiring groove
20. A W plug 30 is exposed at the bottom of the damascene wiring
groove 20.
[0077] As shown in the cross sectional view arranged as the left
side of the third wafer processing equipment 1C, an exposed portion
21 of the LKD film 17 is formed in a part of the sidewall of the
damascene wiring groove 20. The exposed portion 21 is exposed to an
atmosphere in the PIE chamber 2C. At this time, the atmosphere in
the RIE chamber 2C is controlled at a humidity of 30% or less and a
temperature of 75.degree. C. or more. In a separate chamber in the
RIE chamber 2C, the photo resist is ashed by an O.sub.2 ashen At
this time, also, the atmosphere is controlled at a humidity of 30%
or less and a temperature of 75.degree. C. or more. After the
ashing treatment is finished, the temperature of the substrate is
dropped to a predetermined level. At the same time, the atmosphere
in the transfer tube 4C is controlled at a humidity of 30% or less
and a temperature of 75.degree. C. or more. Then, the semiconductor
wafers, provided with the LKD film 17 a part of which is exposed,
are carried out to the transfer tube 4C. And the semiconductor
wafers allowed to pass through the transfer tube 4C. The
semiconductor wafers are transferred to the wafer storing box 3. At
that time, the wafer storing box 3 is controlled at a humidity of
30% or less and a temperature of 75.degree. C. or more. The
semiconductor wafer is stored in a standing state in the wafer
storing box 3, so that no stress is applied. In this manner, in the
wafer is processing equipment 1C, the semiconductor wafers are
provided with the damascene wiring prove, at a part of the
saidewall of which the LKD film 17 is exposed. The semiconductor
wafers arc conveyed from the RIE apparatus 1C to the wafer storing
box 3. At this time, the atmosphere around the semiconductor wafers
are controlled at a humidity of 30% or less and a temperature of
75.degree. C. or more.
[0078] (f) The semiconductor wafer is transferred from the RIE
apparatus 1C to the fourth wafer processing apparatus 1D, by using
the wafer storing box 3. In this transferring period, the
semiconductor wafers are in the stare that a part of the LKD film
is exposed as in sidewall of the groove. During this transfer
period (third transfer period) between the third wafer processing
equipment 1C to the fourth wafer processing equipment 1D, the
semiconductor wafers are stored in the wafer storing box 3, such
that the atmosphere around the semiconductor wafers is controlled
at a humidity of 30% or less and a temperature of 75.degree. C. or
more. The atmosphere around the semiconductor wafers is achieved by
using the humidity control unit 9 and the temperature control unit
8.
[0079] (g) Finally, a metal film 22 is deposited by using the
fourth wafer processing equipment 1D (metal film deposition
apparatus). The whole exposed portion 21 of the LKD film 17 is
coated with the metal film 22. Specifically, the door 24 of the
storing box 3 is brought into close contact with the inlet port of
a transfer tube 4D of the metal film deposition apparatus 1D. By
using the humidity control unit 6 and the temperature control unit
5, the atmosphere in the transfer tube 4D is controlled at a
humidity of 30% or less and the temperature of 75.degree. C. or
more. Then, the door 24 of the storing box 3 was opened in the
above condition. The semiconductor wafers are transferred to the
transfer tube 4D. The semiconductor wafers are carried into a metal
film deposition chamber 2D through the transfer tube 4D, and placed
on a sample table. Then, The metal film deposition apparatus 1D
deposits a metal film 22 on the TEOS film 19 and inside of the
damascene wiring groove 20. The metal film 22 has a predetermined
thickness. In the subsequent processes, usual CMP processes and
further passivation processes are carried out, because the low
dielectric constant insulating film is not exposed.
[0080] The sample of the devices that manufactured through the
above processes, was subjected to a stress migration (SM) and an
electromigration (EM) accelerated test. The sample of the devices
was measured for device properties. As a result, no problem arose.
On the other hand, in the case of a normal clean room, an LKD film
with a thickness of 1.5 .mu.m was formed without controlling the
temperature and the humidity around the LKD film. As a result,
cracks occurred after baked at 450.degree. C.
[0081] (h) One wiring level can be formed by carrying out the above
processes. Accordingly, a semiconductor device, having a desired
number of wiring levels, can be manufactured by carried out
repeatedly the above processes. The electromigration, stress
migration and device properties of the sample of this multi-level
wiring devices was measured. As a result, no problem arose. No
crack of the LKD film was observed.
[0082] As explained above, the atmosphere around the semiconductor
wafer, which provided with the LKD film at least a pan of which is
exposed, is controlled at the humidity of 30% or less and the
temperature of 75.degree. C. or more. The generation and progress
or propagation of cracks in the LKD film can be limited.
[0083] The atmosphere around the semiconductor wafer is controlled
at the humidity of 25% or less at room temperature (23.degree. C.)
or more. It is to be noted that the generation and progress or
propagation of cracks can be limited also. The atmosphere is
preferably an atmosphere of inert gas including N.sub.2 gas or
vacuum. It is also desirable to control low dusts in the storing
box 3 and the transfer tube 4. In the first embodiment, the wafers
are aligned standing at each edges with the view of removing stress
from wafers. In this case, a mechanism for carrying the wafer
sideways is required, when the wafer is conveyed. For this, a wafer
storing box 3, in lit which wafers are placed sideways, may be
used. The wafer storing box 3 is provided with a support plate for
supporting each wafer. Good results were obtained similarly to the
case of the standing state. The support plate is provided with
slits for inserting a carrier robot am.
[0084] In the first embodiment, the explanations have been
furnished taking the LKD film as an example of the low dielectric
constant insulating film. However, a low dielectric constant
insulating film, containing other organic or inorganic components,
is acceptable, For example, as the LKD film, organic SOG films,
organic compound addition type SiO.sub.2 films, may be used.
Further, a SiOF film prepared by adding fluorine to an ordinary
SiO.sub.2 film is acceptable. The organic SOG films are applied by
a spinner. The organic compound addition model SiO.sub.2 films are
formed by a CVD method. Moreover, the TEOS film is used in the
first embodiment. In the case of a device provided with LKD films
in all levels to achieve lower dielectricity, the method of forming
a metal film is preferably carried out by a following CMP. The CMP
uses an organic solvent without using water. At this time, the CMP
is desirably carried out in an inert atmosphere having the humidity
of 25% or less. The low dielectric constant insulating film may be
an insulating film containing silicon, oxygen and fluorine as its
major components, Further, the low dielectric constant insulating
film may be an insulating film containing an organic component,
oxygen and silicon as its major components. The organic component
includes a methyl group or an ethyl group.
[0085] Second Embodiment
[0086] FIG. 11 is a block diagram showing the structures of a wafer
processing equipment 31 and a wafer storing box 23, according to
the second embodiment of the present invention, As shown FIG. 11,
the wafer processing equipment 31 encompasses a wafer processing
chamber 2, a transfer tube 4, a vacuum exhaust unit 25, a nitrogen
gas replacing unit 26, and vacuum valves (11, 12). The transfer
tube 4 is connected to the wafer processing chamber 2. The
semiconductor wafer is carried into and out from the wafer
processing chamber 2 through the transfer tube 4. The vacuum
exhaust unit 25 evacuates air of the transfer tube 4. The nitrogen
gas replacing unit 26 replaces the atmosphere in the transfer tube
4 by nitrogen (N.sub.2) gas. The vacuum valves (11, 12) is
connected respectively to both ends of the transfer tube 4.
[0087] The wafer processing chamber 2 may be one of various
apparatuses used in all wafer process. The wafer processing chamber
2 includes depositing a low dielectric constant insulating film
(for example, SiOF film), exposing at least a part of the low
dielectric constant insulating film, coating whole exposed part,
and various process performed between these processes, in the same
manner as in the first embodiment. The atmospheric ambient around
the semiconductor wafer in the wafer processing chamber 2 is
controlled at the humidity of 30% or less and the temperature of
75.degree. C. or more. The transfer tube 4 is connected to the
wafer processing chamber 2 through the vacuum valve 11. Here, a
SiO.sub.2 film generally has a dielectric constant of 3.9 to 4.1,
though it differs depending on the manufacturing method. On the
contrary, a SiOF film, having a low dielectric constant, can be
formed by adding fluorine in a SiO.sub.2 film. For example,
fluorine contained in a concentration of only about 11.0% makes it
possible to decrease the dielectric constant to about 3.3. As to
also the manufacturing method, the SiOF film can be formed only by
mixing additional gas. The additional gas contains fluorine (for
example, NF.sub.3, CF.sub.4 and C.sub.2F.sub.6) in the gas
(SiH.sub.4/O.sub.2 gas or TEOS/O.sub.2 gas) used in a plasma CVD
method. Ad Therefore, the SiOF film is widely used as one of low
dielectric constant insulating films.
[0088] The wafer storing box 23 controls the atmospheric ambient
around a semiconductor wafer when the semiconductor wafer is
provided with the low dielectric constant insulating film; at least
a part of which is exposed. The wafer storing box 23 comprises a
wafer storing chamber 7, a vacuum exhausting unit 27, and a
nitrogen replacing unit 28. The wafer storing chamber 7 stores the
semiconductor wafers on which the low dielectric constant
insulating film is deposited. The vacuum exhausting unit 27
evacuates the wafer storing chamber 7 of air. The nitrogen
replacing unit 28 replaces the atmosphere in the wafer storing
chamber 7 by nitrogen gas. The wafer storing box 23 is further
provided with a door 24, The door 24 is opened and closed in close
contact with an inlet/outlet port of the transfer tube 4. The door
24 is adjustable to the size of the inlet/outlet port of the
transfer tube 4.
[0089] For preventing dielectric breakdown or device destruction by
the static electricity, it is desirable that the humidity control
unit 26, 28 has an ion generation apparatus. By having the ion
generation apparatus, it is possible to perfectly suppress the
generation of the trouble by the electrostatic destruction.
[0090] A method for manufacturing a semiconductor device, using the
wafer processing equipment 31 and wafer storage box 23, shown in
FIG. 11 will be explained.
[0091] (a) At first, a SiOF film is deposited on a base substrate,
processed as desired in advance. The first wafer processing
equipment is a high density plasma CVD apparatus manufactured by
Applied Materials, Inc. The formation gas, introduced into the
equipment, is mixture gas of SiH.sub.4/SiF.sub.4O.sub.2/Ar. The
SiOF film after deposited is exposed.
[0092] b) Next, a SiO.sub.2 film is formed on the surface of the
SiOF film by using second wafer processing equipment (parallel
plate type plasma CVD apparatus manufactured by Applied Materials,
Inc). The parallel plate type plasma CVD apparatus is different
from the first wafer processing equipment. The exposed surface of
the SiOF film is coated with the SiO.sub.2 film.
[0093] (c) Then, a groove and a via-hole, for forming a metal
wiring, are digged by using a dry etching apparatus (third wafer
process equipment). A part of the SiOF film is exposed in the
groove and the via-hole.
[0094] (d) Then, a metal film is deposited in the groove, in the
via-hole and on the SiO.sub.2 film by using fourth wafer process
equipment. The exposed portion of the SiOF film is coated with the
metal film in the groove and the via-hole.
[0095] (e) Then, an unnecessary metal part is removed. The film is
flattened by CMP, to form a metal wiring corresponding to one
level, The above processes are repeated to thereby form a
multi-level wiring structure.
[0096] In this series of manufacturing processes, the processing
equipment and the transfer period, in which at least a part of the
SiOF film is exposed, is limited to the first wafer processing
equipment, a period between the first wafer processing equipment
and the second wafer processing equipment, the third wafer
processing equipment, and a period between the third wafer
processing equipment and the fourth wafer processing equipment.
Because the first wafer processing equipment and the third wafer
processing equipment are performed in a reduced pressure
circumstance, the atmospheric ambient around the semiconductor
wafer is controlled at the humidity of 30% or less. Problems
concerning humidity in the atmospheric ambient around the
semiconductor wafer, arise when the semiconductor wafer is carried
into and out from the wafer processing equipment. At this time,
nitrogen gas is used in order to control the humidity at 30% or
less.
[0097] Specifically, the semiconductor wafers, which have been
processed by predetermined wafer treatment, are carried out from
the wafer processing chamber 2 to the transfer tube 4. At this
time, the atmosphere in the transfer tube 4 is controlled using the
method shown below. The vacuum valves (11, 12) on both ends of the
transfer tube 4 are closed. The atmospheric ambient in the transfer
tube 4 is evacuated using the vacuum exhaust unit 25. Then, when
the evacuation is completed to a prescribed vacuum level, the
evacuation is stopped. Dry nitrogen gas is introduced into the
transfer tube 4 by using the nitrogen gas replacing unit 26. The
vacuum valve 11 is opened in the condition of the transfer tube 4
with an atmospheric ambient, substituted with dry nitrogen gas by
the above procedures. The semiconductor wafers, stored in the wafer
processing chamber 2, are transferred to the transfer tube 4. In
the same procedures as above, the atmospheric ambient in the wafer
storing chamber 7 of the storing box 23 is replaced by dry
nitrogen. The vacuum valve 12 is opened to carry out the
semiconductor wafers to the wafer storing box 23. The semiconductor
wafers are handled in this manner during carry-in and carry-out
between the first wafer processing equipment and the second wafer
processing equipment, and between the third wafer processing
equipment and the forth wafer processing equipment. The humidity
around the semiconductor wafers provided with the SiOF film, a part
of which is exposed, can be controlled at 30% or less.
[0098] As described above, in the method for manufacturing a
semiconductor device formed with the SiOF film, the atmospheric
ambient around the semiconductor wafers provided with the SiOF
film, a part of which is exposed, is controlled at a humidity 30%
or less. The atmospheric ambient around the semiconductor wafers is
achieved by using the vacuum exhaust unit (25, 27) and the nitrogen
gas replacing unit (26, 28). It can be limited that the occurrence
and progress or propagation of cracks in the SiOF film, and the
problem concerning the peeling of the upper level metal film. The
peeling is caused in the heating processes.
[0099] In the second embodiment, the wafer processing equipment 31
and the wafer storing box 23 are provided with the vacuum exhaust
unit (25, 27) and the nitrogen gas replacing unit (26, 28)
respectively is explained. However, even if the wafer processing
equipment 31 and the wafer storing box 23 are provided with either
one of these units, the effect of the second embodiment is
manufactured. For example, in a the case of using only the vacuum
exhaust unit (25, 27), the atmospheric ambient around the
semiconductor wafer may be in vacuum (reduced pressure) state. On
the other hand, in the case of using only the nitrogen gas
replacing unit (26, 28), the atmospheric ambient around the
semiconductor wafers can be filled with dry nitrogen gas. The
atmospheric ambient is achieved by flowing nitrogen gas always
under uplift pressure in the transfer tube 4 and the wafer storing
chamber 7. In this case, an inert gas atmospheric ambient using
inert gas other than nitrogen gas may be adopted. It is possible to
use, for example, hydrogen (H.sub.2) gas or rare gas such as He, Ar
or Kr.
[0100] In the second embodiment, explanations are furnished, taking
the SiOF film prepared by adding fluorine to an ordinary SiO.sub.2
film, as an example of the low dielectric constant insulating film.
A low dielectric constant insulating film containing other organic
or inorganic components may be used. It may be used that LKD films
such as organic SOG films and organic compound-addition SiO.sub.2
films. The organic SOG films is applied by a spinner. The organic
compound-addition SiO.sub.2 is formed by a CVD method.
[0101] According to the embodiments of the present invention, the
crack resistance and adhesion of the low dielectric constant
insulating film are improved. Therefore a highly reliable
semiconductor device can be manufactured in a high yield. Further,
the absorption of moisture, in the low dielectric constant
insulating film, is suppressed. The processes of manufacturing the
semiconductor device can be decreased.
[0102] Additional advantages and modifications will readily occur
to those skilled in the art. Therefore, the invention in its
broader aspects is not limited to the specific to details and
representative embodiments shown and described herein. Accordingly,
various modifications may be made without departing from the spirit
or scope of the general inventive concept as defined by the
appended claims and their equivalents.
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