U.S. patent application number 09/157936 was filed with the patent office on 2001-12-06 for method of film formation and method for manufacturing semiconductor device.
Invention is credited to MAEDA, KAZUO, NISHIMOTO, YUHKO.
Application Number | 20010049202 09/157936 |
Document ID | / |
Family ID | 15212626 |
Filed Date | 2001-12-06 |
United States Patent
Application |
20010049202 |
Kind Code |
A1 |
MAEDA, KAZUO ; et
al. |
December 6, 2001 |
METHOD OF FILM FORMATION AND METHOD FOR MANUFACTURING SEMICONDUCTOR
DEVICE
Abstract
This invention relates to a method of film formation in which,
when a silicon oxide film (a NSG film: a Non-doped Silicate Glass)
is formed on a substrate having a recess by a CVD method using a
mixed gas containing a TEOS and ozone, a surface dependency of the
substrate is deleted to embed a silicon oxide film into the recess
of the surface thereof. The invention comprises a process forming a
phosphorus containing insulating film 14 as a base layer on the
surface of a substrate 11 and a process forming a
silicon-containing insulating film 15 on the phosphosilicate glass
film 14 by the chemical vapor deposition method used a mixed gas
containing a ozone-containing gas and a silicon-containing gas.
Inventors: |
MAEDA, KAZUO; (KANAGAWA,
JP) ; NISHIMOTO, YUHKO; (TOKYO, JP) |
Correspondence
Address: |
GEORGE A LOUD
LORUSSO LOUD
3137 MOUNT VERNON AVENUE
ALEXANDRIA
VA
22305
|
Family ID: |
15212626 |
Appl. No.: |
09/157936 |
Filed: |
September 22, 1998 |
Current U.S.
Class: |
438/778 ;
257/E21.275; 257/E21.279; 257/E21.548; 438/787 |
Current CPC
Class: |
H01L 21/02304 20130101;
H01L 21/02164 20130101; H01L 21/02271 20130101; H01L 21/31612
20130101; H01L 21/02129 20130101; H01L 21/31625 20130101; H01L
21/76229 20130101; H01L 21/02337 20130101 |
Class at
Publication: |
438/778 ;
438/787 |
International
Class: |
H01L 021/31; H01L
021/469 |
Foreign Application Data
Date |
Code |
Application Number |
May 20, 1998 |
JP |
10-138040 |
Claims
What is claimed is:
1. A method of film formation comprising the steps of: forming a
phosphorus-containing insulating film on a surface of a substrate
as a base layer; and forming a silicon-containing insulating film
on said phosphorus-containing insulating film by a chemical vapor
deposition using a mixed gas containing a ozone-containing gas and
a silicon-containing gas.
2. The method of film formation according to claim 1, wherein after
a step of forming said phosphorus-containing insulating film and
before a step of forming the silicon-containing insulating film on
said phosphorus-containing insulating film, a surface of said
phosphorus-containing insulating film is exposed to the atmosphere,
or the surface of said phosphorus-containing insulating film is
exposed to water vapor while heating the surface of said
phosphorus-containing insulating film.
3. The method of film formation according to claim 1, wherein a
film thickness of said phosphorus-containing insulating film
deposited is within the range of 10 nm to 100 nm.
4. The method of film formation according to claim 1, wherein said
ozone-containing gas is a gas containing ozone of a concentration
of not more than 10% in oxygen.
5. The method of film formation according to claim 1, wherein said
silicon-containing gas is a gas containing tetraethylorthosilicate
(TEOS).
6. The method of film formation according to claim 1, wherein a
deposition temperature during forming said silicon-containing
insulating film is within the range of 350.degree. C. to
550.degree. C.
7. The method of film formation according to claim 6, wherein the
deposition temperature during forming said silicon-containing
insulating film is within the range of 375.degree. C. to
425.degree. C.
8. The method of film formation according to claim 1, wherein said
phosphorus-containing insulating film is any one of a
phosphosilicate glass film (a PSG film) and a borophosphosilicate
glass film.
9. The method of film formation according to claim 8, wherein a
phosphorus concentration in said phosphosilicate glass film is not
more than 10 mol %.
10. A method of film formation comprising the steps of: discharging
a ozone-containing gas, a silicon-containing gas and a
phosphorus-containing gas by a first gas discharge means to form a
phosphorus-containing insulating film on a surface of a substrate
as a base layer by a chemical vapor deposition; and discharging the
ozone-containing gas and the silicon-containing gas by a second gas
discharge means which differs from said first gas discharge means
continuously after ceasing the discharge by the first gas discharge
means to form a silicon-containing insulating film on said
phosphorous-containing insulating film by the chemical vapor
deposition.
11. The method of film formation according to claim 10, wherein
after a step of forming said phosphorus-containing insulating film
and before a step of forming the silicon-containing insulating film
on said phosphorus-containing insulating film, a surface of said
phosphorus-containing insulating film is exposed to the atmosphere,
or the surface of said phosphorus-containing insulating film is
exposed to water vapor while heating the surface of said
phosphorus-containing insulating film.
12. The method of film formation according to claim 10, wherein a
film thickness of said phosphorus-containing insulating film
deposited is within the range of 10 nm to 100 nm.
13. The method of film formation according to claim 10, wherein
said ozone-containing gas is a gas containing ozone of a
concentration of not more than 10% in oxygen.
14. The method of film formation according to claim 10, wherein
said silicon-containing gas is a gas containing
tetraethylorthosilicate (TEOS).
15. The method of film formation according to claim 10, wherein a
deposition temperature during forming said silicon-containing
insulating film is within the range of 350.degree. C. to
550.degree. C.
16. The method of film formation according to claim 15, wherein the
deposition temperature during forming said silicon-containing
insulating film is within the range of 375.degree. C. to
425.degree. C.
17. The method of film formation according to claim 10, wherein
said phosphorus-containing insulating film is any one of a
phosphosilicate glass film (a PSG film) and a borophosphosilicate
glass film.
18. The method of film formation according to claim 17, wherein a
phosphorus concentration in said phosphosilicate glass film is not
more than 10 mol %.
19. A method for manufacturing a semiconductor device comprising
the steps of: forming the phosphorus-containing insulating film for
sheathing a recess as the base layer on the surface of the
substrate having said recess; and subsequently forming a
silicon-containing insulating film on said phosphorus-containing
insulating film by a chemical vapor deposition using a mixed gas
containing a ozone-containing gas and a silicon-containing gas, so
that said recess is embedded with the silicon oxide film.
20. A method of film formation comprising the steps of: discharging
a ozone-containing gas, a silicon-containing gas and a
phosphorus-containing gas by a first gas discharge means to form a
phosphorus-containing insulating film for sheathing a recess on a
surface of a substrate having said recess as a base layer by a
chemical vapor deposition; and discharging the ozone-containing gas
and the silicon-containing gas by a second gas discharge means
which differs from said first gas discharge means continuously
after ceasing the discharge by the first gas discharge means to
form a silicon-containing insulating film on said
phosphorous-containing insulating film by the chemical vapor
deposition, so that said recess is embedded with the silicon oxide
film.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a method of film formation and a
method for manufacturing a semiconductor device in which, when a
silicon oxide film (a NSG film: a Non-doped Silicate Glass) is
formed on a substrate having a recess by a CVD method using a mixed
gas containing a TEOS and ozone, a surface dependency of the
substrate is deleted to embed a silicon oxide film into the recess
of the surface thereof.
[0003] The surface dependency is defined as a property such that a
film formation depends on a property of a surface on which a film
is deposited.
[0004] 2. Description of the Prior Art
[0005] In recent years, micronizing has been advanced in the
semiconductor device. The recess narrow in width and deeper in
depth such as the recess between wirings and the recess in which an
insulating material is embedded for an insulating element
separation is designed to be formed on a semiconductor substrate
surface. In such semiconductor device, an insulating film is
required to be embedded in the recess.
[0006] Therefore, the silicon oxide film excellent in film quality
(hereinafter referred to as a High O.sub.3/TEOS SiO.sub.2 film) is
required to be formed and to be embedded in the recess without
clearance. A CVD method is used as a method of the film formation.
Mixed gas containing both the TEOS (Tetraethylorthosilicate) and
the ozone-containing gas containing high concentration O.sub.3 is
used as a deposition gas, said ozone-containing gas containing
O.sub.3 of 1% or more in O.sub.2.
[0007] However, since the High O.sub.3/TEOS SiO.sub.2 film is
sensitive to a property of the surface of the substrate, a property
of a depositing film tends to be influenced. An influence of the
surface dependency appears as reduction of a film formation rate,
surface roughness of the depositing film and reduction of film
quality. Therefore, in order to deposit the High O.sub.3/TEOS
SiO.sub.2 film having the same film formation rate, surface
condition of the depositing film and the film quality of the
depositing film where the film on a silicon substrate is deposited,
it is required for the surface of the substrate to design the film
formation of the High O.sub.3/TEOS SiO.sub.2 film to be not
influenced by the surface dependency. Heretofore, in order to
delete such surface dependency, the following countermeasures are
given:
[0008] {circle over (1)} The silicon oxide film is formed as a base
layer on the surface of the substrate by a plasma enhanced CVD.
This is disclosed in Japanese Laid-open Patent Publication
No.Hei.7-211712.
[0009] {circle over (2)} The surface of the substrate is exposed to
plasma gases. This is disclosed in Japanese Laid-open Patent
Publication No.Hei.4-94539.
[0010] {circle over (3)} The silicon oxide film hereinafter
referred to as a Low O.sub.3/TEOS SiO.sub.2 film) is formed as a
base layer on the surface of the substrate by the CVD method. As
the film formation gas, the reaction gas containing the
ozone-containing gas containing low concentration O.sub.3 whose the
concentration of O.sub.3 in O.sub.2 is less than 1% and the TEOS is
used. This is disclosed in Japanese Laid-open Patent Publication
No.Hei.3-198340. Furthermore, the following method that the methods
described above are combined is used.
[0011] {circle over (4)} The Low O.sub.3/TEOS SiO.sub.2 film is
formed as the base layer on the surface of the substrate by the CVD
method and subsequently, the Low O.sub.3/TEOS SiO.sub.2 film is
exposed to plasma gases. A reaction gas containing both the TEOS
and a low ozone-containing gas such that the concentration of
O.sub.3 in O.sub.2 is as low as less than 1% is used as the film
formation gas of the Low O.sub.3/TEOS SiO.sub.2 film.
[0012] {circle over (5)} The High O.sub.3/TEOS SiO.sub.2 film is
formed as the base layer on the surface of the substrate by the CVD
method and subsequently, the High O.sub.3/TEOS SiO.sub.2 film is
exposed to plasma gases. A reaction gas containing both the TEOS
and a high ozone-containing gas such that the concentration of
O.sub.3 in O.sub.2 is as high as not less than 1% is used as the
film formation gas of the High O.sub.3/TEOS SiO.sub.2 film.
[0013] In addition, the methods for delating the surface dependency
of the substrate are disclosed in Japanese Laid-open Patent
Publication No.Hei.7-66131 or the like.
[0014] By such method, the O.sub.3/TEOS SiO.sub.2 film of which the
depositing film does not depend upon the surface dependency of the
substrate and which has the sufficient fluid ability can be
formed.
PROBLEMS TO BE SOLVED BY THE INVENTION
[0015] However, in the methods for deleting the surface dependency
described above, there are the following problems:
[0016] That is, in the method forming the silicon oxide film as the
base layer on the surface of the substrate by the CVD method
described in the item {circle over (1)},
[0017] since the silicon oxide film by the plasma enhanced CVD
method is poorly good in step coverage, it is not suitable for
embedding the recess narrow in width and deeper in depth.
[0018] Moreover, in the method of the item {circle over (2)}
exposing the surface of the substrate to plasma gases, since a
plasma apparatus is required, the apparatus becomes extensive.
Moreover, in such method, there are problems that an increase in
cost is led and it is a question whether reform can be performed up
to the bottom of the recess narrow in width and deeper in depth or
not by the plasma.
[0019] Furthermore, in the method of the item {circle over (3)}, a
thickness of the Low O.sub.3/TEOS SiO.sub.2 film is required at
least 50 nm or more. It is not suitable for embedding to the recess
narrow in width and deeper in depth.
[0020] Moreover, with regard to the item {circle over (4)} and the
item {circle over (5)} also, there are the same problems as the
item {circle over (2)} and the item {circle over (3)}.
SUMMARY OF THE INVENTION
[0021] It is the object of this invention to provide a method of
film formation and a method for manufacturing a semiconductor
device capable of securely deleting the surface dependency of the
substrate to form an insulating film being excellent in film
quality.
[0022] The object of this invention is to provide a method of film
formation and a method for manufacturing a semiconductor device
capable of embedding the insulating film without clearance in a
recess of the substrate having the recess narrow in width and
deeper in depth.
[0023] As described above, in this invention, a
phosphorus-containing insulating film such as a phosphosilicate
glass film is formed as a base layer on the surface of the
substrate. Furthermore, on the phosphorus-containing insulating
film, a silicon-containing insulating film is formed by a chemical
vapor film formation using the mixed gas containing the
ozone-containing gas and a silicon-containing gas.
[0024] According to experiments by the inventor of the application
concerned, in the case of depositing the silicon-containing
insulating film by a chemical vapor deposition method using the
mixed gas containing the ozone containing gas and a
silicon-containing gas on the substrate, the surface dependency of
the substrate can be deleted by sheathing the surface of the
substrate with the phosphorus-containing insulating film such as a
phosphosilicate glass film (a PSG film) or a borophosphosilicate
glass film (BPSG film).
[0025] Incidentally, it has been stated that, when the High
O.sub.3/TEOS SiO.sub.2 film is formed by the chemical vapor
deposition method using the ozone-containing gas and a
silicon-containing gas containing high concentration ozone (defined
as the concentration of ozone in oxygen is 1% or more), the surface
dependency to the deposition film on the substrate appears
remarkably. According to the invention, since the surface
dependency can be deleted by sheathing the surface of the substrate
with the phosphorus containing insulating film, the sufficient
fluid ability can be obtained, even when the High O.sub.3/TEOS
SiO.sub.2 film being ready to be influenced by the surface
dependency is deposited.
[0026] Moreover, the surface dependency can be deleted sufficiently
by phosphorus-containing insulating film with a thin film thickness
of approximate 10 nm in film thickness. Therefore, even the inside
of the recess narrow of, at least, approximate 20 nm or more in
width can be sheathed. Moreover, the upper limit of the film
thickness of phosphorus-containing insulating film is influenced by
the width of the recess. At this point of time, the film thickness
of the phosphorus-containing insulating film is defined preferably
such that the film thickness of the phosphorus-containing
insulating film becomes thin sufficiently as compared with the
silicon-containing insulating film in the entire film thickness of
an interlayer dielectric film constituted by the phosphorus
containing insulating film as the base layer and the silicon
containing insulating film which lies thereon. Usually, it can be
acceptable sufficiently when being formed within approximate 100
nm.
[0027] Therefore, when there is the recess narrow in width and
deeper in depth on the surface of the substrate, recess can be
embedded with the silicon oxide film without clearance, without
generating voids and seams on the silicon oxide film formed in
recess.
[0028] In this case, the ozone-containing gas, the
silicon-containing gas and the phosphorus-containing gas are
discharged by a first gas discharge means to form the
phosphorus-containing insulating film and then the ozone-containing
gas and the silicon-containing gas are discharged by a second gas
discharge means continuously after ceasing the discharge by the
first discharge means to form the silicon oxide film. Incidentally,
it has been found by the experiments that in order to delete the
surface dependency of the surface of the phosphorus-containing
insulating film, when subsequently forming the silicon-containing
insulating film on the phosphorus-containing insulating film, it is
required to perform such that no phosphorus-containing gas is
contained in the reaction gas. That is, when the silicon-containing
insulating film is formed using a gas discharge means which differs
from the gas discharge means where forming the
phosphorus-containing insulating film, the surface dependency at
the surface of the phosphorus-containing insulating film can be
deleted. A deposition chamber for the phosphorus-containing
insulating film may be swapped with a deposition chamber for the
silicon-containing insulating film or the alternate gas discharge
means may be switched respectively upon forming also.
[0029] Moreover, the following fact has been verified by the
experiments. After the process forming the phosphorus-containing
insulating film and before the process forming the
silicon-containing insulating film on the phosphorus-containing
insulating film, the surface of the phosphorus-containing
insulating film is exposed to the atmosphere, or the surface of the
phosphorus-containing insulating film is exposed to water vapor
while heating the surface of the phosphorus-containing insulating
film. Therefore, the surface of the phosphorus-containing
insulating film is converted to hydrophobicity, and when the
surface of the phosphorus-containing insulating film is converted
to hydrophobicity, the surface dependency in the mentioned-above
depositing film can be suppressed. Especially, when the High
O.sub.3/TEOS SiO.sub.2 film being ready to be influenced by the
surface dependency is deposited, such treatment is performed
preferably.
[0030] Furthermore, the ozone-containing gas used in the film
formation of the silicon-containing insulating film is the gas
containing ozone of the concentration of less than 10% in
oxygen.
[0031] As described above, to use the phosphorus-containing
insulating film as the base layer is effective, in particular, when
depositing the High O.sub.3/TEOS SiO.sub.2 film being ready to be
influenced by the surface dependency using the high
ozone-containing gas such that the concentration of ozone in oxygen
is as high as 1% or more.
[0032] As a matter of course, this is effective also when
depositing the silicon oxide film (the Low O.sub.3/TEOS SiO.sub.2
film) being not ready to be influenced by the surface dependency
using the low ozone containing gas such that the concentration of
ozone in oxygen is as low as less than 1%.
[0033] The reason why is that according to this deposition,
penetration of moisture and migration of alkali ions from the Low
O.sub.3/TEOS SiO.sub.2 film to the substrate can be prevented.
[0034] In the case of depositing the silicon-containing insulating
film by CVD method using the mixed gas of the O.sub.3/TEOS, the
flowability of the depositing film can be increased by regulating
the deposition temperature within the range of 350.degree. C. to
550.degree. C. In the described-above deposition temperature, in
order to obtain the particularly sufficient flowability of the
depositing film, it is preferable that the deposition temperature
is regulated within the range of 375.degree. C. to 425.degree.
C.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] FIG. 1A to FIG. 1C are flowcharts of a method of film
formation and a method for manufacturing a semiconductor device
according to embodiments of the invention.
[0036] FIG. 2A and FIG. 2B are photography showing cross-section
shapes of a silicon-containing insulating film formed on a
substrate with a step and a groove by the method of film formation
and the method for manufacturing the semiconductor device according
to embodiments of the invention.
[0037] FIG. 3A is a sectional view showing a substrate with a step
used in the method of film formation and the method for
manufacturing the semiconductor device according to embodiments of
the invention.
[0038] FIG. 3B is a sectional view showing a substrate with a
trench groove used in the method of film formation and the method
for manufacturing the semiconductor device according to embodiments
of the invention.
[0039] FIG. 4 is a view showing the correlation between the surface
dependency of a deposition rate and an angle of contact of the
O.sub.3/TEOS NSG film being formed by the method of film formation
according to embodiments of the invention.
[0040] FIG. 5 is a graph obtained by investigating, by showing
types of the base layers as a parameter, the correlation between
the ratio of the deposition rates and an ozone concentration of the
O.sub.3/TEOS NSG film being formed by the method of film formation
according to embodiments of the invention.
[0041] FIG. 6 is a side view showing a constitution of a deposition
chamber applied to the method of film formation according to
embodiments of the invention.
[0042] FIG. 7 is a sectional view showing cross-section shape of a
silicon-containing insulating film formed on a substrate with the
step and the groove by the method of film formation according to a
comparison example.
DESCRIPTION OF THE PREFRRED EMBODIMENTS
[0043] Hereafter, the embodiments of the invention are described
referring to the drawings.
[0044] (1) Basic Data of this Invention
[0045] This invention is based on knowledge in the depositing
reaction of the O.sub.3/TEOS SiO.sub.2 film in the case using a
chemical vapor deposition method (a CVD method) as described below
items (i) to (iv).
[0046] (i) The flowability during depositing the O.sub.3/TEOS
SiO.sub.2 film appears at the deposition temperature within the
range of 375.degree. C. to 425.degree. C.
[0047] On the other hand, when the deposition temperature exceeds
450.degree. C., isotropic growth is shown. At temperature exceeding
500.degree. C., the deposition of the silicon-containing insulating
film by the CVD method used the mixed gas of O.sub.3+TEOS
(hereinafter represented as an O.sub.3/TEOS) becomes the perfectly
isotropic deposition.
[0048] In this case, the silicon-containing insulating film 4 is
also capable of being formed in a narrow and deep recess 3 as shown
in FIG. 7. However, a void 5 or slit 6 may occur if a thickness of
the silicon-containing insulating film 4 is thicker.
[0049] (ii) FIG. 4 is a view showing the relationship among a
property of the surface whether the base layer surface is
hydrophilic or hydrophobic, an angle of contact (.theta.) of water
deposited on a base layer surface and the ratio of the deposition
rates of various films being formed on the base layer.
[0050] As shown in FIG. 4, where an angle of contact (.theta.)
refers to the angle which the tangent to the drop of water at the
contact surface with the base layer surface forms with the base
layer surface, when water deposited on a base layer surface is
flocculated to make a drop of water by surface tension. A ratio of
the deposition rates refers to the ratio of the deposition rate
where the same film is film-deposited on various base layers with
respect to the deposition rate where various films are formed on
silicon surface directly. It is shown that as the ratio of the film
deposition rates approaches 1, the surface dependency is more
suppressed.
[0051] Moreover, the term "Th.SiO.sub.2" in FIG. 4 refers to the
silicon oxide film formed by thermal oxidation. The term "AD"
refers to "as deposited", that is, the meaning of "immediately
after deposition". The term "EX" refers to "after exposure", that
is, the meaning of "after exposing to the atmosphere".
[0052] In the comparison data of the ratio of the deposition rates,
the high ozone-containing gas that the concentration of ozone in
oxygen is 5% is used as an oxidizing gas used in the film formation
of a phosphosilicate glass (PSG)(AD), an impurity-free silicon
oxide film (NSG), a borophosphosilicate glass film (BPSG) and PSG
(EX) in various films.
[0053] As shown in FIG. 4, the surface dependency of the
O.sub.3/TEOS SiO.sub.2 film to the base layer is influenced
depending upon the angle of contact (.theta.) of water deposited on
the base layer surface, that is, whether being hydrophilic or
hydrophobic.
[0054] That is, when the surface of the base layer is hydrophilic,
the surface dependency of the depositing film is high, and when the
surface of the base layer is hydrophobic, the surface dependency of
the depositing film is low. Moreover, in FIG. 4, the reason why
even though the NSG is hydrophilic, the surface dependency of the
depositing film to the base layer is low is unknown with the
current state of the art.
[0055] (iii) FIG. 5 is a graph showing the relationship between the
ozone concentration in the ozone-containing gas used in film
formation of the NSG film deposited on the base layer and the ratio
of the deposition rates of the NSG film. The various films as the
base layers are shown as a parameter.
[0056] The ratio of the deposition rates expressed in a linear
scale is shown on the vertical axis the horizontal axis. The
concentration of ozone (%) in oxygen expressed in a linear scale is
shown on the horizontal axis.
[0057] Moreover, in the indication of the various films as the base
layers, the indication of "NSG 4% AD" shows that it is the NSG film
formed using the ozone-containing gas that the concentration of
ozone is less than 4%. In addition, it shows that immediately after
deposition, deposition is performed thereon.
[0058] The indication of "PSG 2 mol % EX" shows that it is the PSG
film containing phosphorus of 2 mol % and after exposing to the
atmosphere, deposition is performed thereon.
[0059] The indication of "PSG 4 to 6 mol % EX" refers to the PSG
film containing phosphorus of 4 to 6 mol %.
[0060] The indication of "BPSG 8 to 8 mol % AD" shows that it is
the BPSG film containing boron of 8 mol % and phosphorus of 8 mol %
and immediately after deposition, deposition is performed
thereon.
[0061] Other indications conform to the described-above
indications. Moreover, the concentration of ozone in the
ozone-containing gas used in deposition of the PSG film and the
BPSG film is both defined as 4%.
[0062] As shown in FIG. 5, there is the significant correlation
between the concentration of ozone in the ozone-containing gas used
in deposition of the silicon-containing insulating film and the
surface dependency.
[0063] Moreover, in the case that the base layer is the PSG,
immediately after deposition of the base layer (AD), the surface
dependency in the base layer is high. However, it is understood
that when the base layer is exposed to the atmosphere (EX), the
surface of the base layer is converted from hydrophilic to
hydrophobic, whereby the surface dependency of the depositing film
become low.
[0064] Next, the degree of the surface dependency according to the
type of the base layer is shown in Table 1.
1TABLE 1 Surface dependency Type depositing film Type of base layer
High High O.sub.3 NSG film Th.SiO.sub.2 (DR < 0.7) HD PSG (AD)
SOG Low High O.sub.3 NSG film BSG, PSG (EX) (0.7 < RD < 1.0)
BSG film BPSG, P--SiO SiN No dependence High O.sub.3 NSG film
P--SiO, Al, refractory metal polysilicon, silicon PSG film, BPSG
film Every type of clean Low O.sub.3 NSG film substrate Note) 1. A
High O.sub.3 NSG film refers to a High O.sub.3/TEOS SiO.sub.2 film.
2. A Low O.sub.3 NSG film refers to a Low O.sub.3/TEOS SiO.sub.2
film. 3. A HD PSG (AD) refers to the PSG film which contains a high
concentration phosphorus and is the film immediately after being
formed. 4. PSG (EX) refers to the posterior PSG film which was
exposed to the atmosphere after deposition. 5. A P--SiO refers to
the silicon oxide film deposited by plasma of gas containing the
TEOS.
[0065] Table 1 is the table comparing the degrees of the surface
dependencies where the Low O.sub.3 NSG film (referred to the Low
O.sub.3/TEOS SiO.sub.2 film) base layer, the High O.sub.3 NSG film
(refer to the High O.sub.3/TEOS SiO.sub.2 film), the BSG film, the
PSG film or the BPSG film are formed on the various films as the
base layer.
[0066] According to Table 1, the High O.sub.3 NSG film is
influenced strongly by the surface dependency of the base layer
when being deposited on a Th. SiO.sub.2, HDPSG (AD) (refer to a
high concentration phosphorus-containing PSG film (AD)) or a SOG
(Spin-On-Glass) as the base layer. That is, the ratio of the
deposition rates (DR) becomes less than 0.7.
[0067] On the other hand, the influence by the surface dependency
of the base layer is an intermediate degree, when the High O.sub.3
NSG film is deposited on BPSG, BSG, PSG (EX), or P-SiO film as the
base layer. That is, the ratio of the deposition rates (DR) becomes
0.7 or more and less than 1.
[0068] Moreover, in the case of depositing a P--SiO, it is not
influenced perfectly by the surface dependency under that P--SiO
film. Furthermore, even when on any type of surface, the PSG film
and the BPSG film beginning with the Low O.sub.3 NSG film are
deposited, these films are not influenced perfectly by the surface
dependency under the PSG film and the BPSG film.
[0069] Moreover, a P--SiO film is the silicon oxide film deposited
using plasma of a gas containing the TEOS. Moreover, a "SiN film"
represents the silicon nitride film.
[0070] Other films can be interpreted in conformance with the
described-above description.
[0071] (iv) When the O.sub.3/TEOS SiO.sub.2 film is deposited on
the base layer, a so-called barrier layer or a shield layer is
required between the base layer and the O.sub.3/TEOS SiO.sub.2
film. The barrier layer or the shield layer is required for
insulating the O.sub.3/TEOS SiO.sub.2 film and the base layer
surface, for preventing moisture from transmitting and for deleting
the surface dependency of the depositing film in the base layer or
the like. Moreover, the base layer surface being exposed to some
types of materials is required to be uniformed.
[0072] This invention is devised based on the knowledge described
above, and hereinafter, embodiments of the invention are
described.
[0073] (2) Embodiments of the Invention
[0074] FIG. 1A to FIG. 1C are sectional views illustrating the
embodiments of the invention. FIG. 6 is a side view showing a
constitution of the deposition chamber.
[0075] First, a substrate 11 shown in FIG. 1A is placed on a
placing table 104 in a deposition chamber 101. On the surface of
the substrate 11, asperties are caused by a step (a recess) 12 and
a groove (a recess) 13. For example, as shown in FIGS. 3A and 3B,
such asperties are the asperties being caused by a trench groove 22
formed on a surface of a semiconductor substrate 21 and wiring 24a
and 24b formed on a base insulating layer 23.
[0076] Subsequently, the substrate 11 is heated to be kept within
the temperature of 350.degree. C. to 550.degree. C. The temperature
is kept preferably within 375.degree. C. to 425.degree. C. In this
embodiment, for example, it is defined as 400.degree. C.
[0077] Next, as shown in FIG. 1B, a phosphosilicate glass film (a
phosphorus-containing insulating film) 14 thin in thickness is
deposited on the surface of the substrate 11 as the base layer by
the CVD method. For this purpose, a gas conduit 112a reaching a gas
discharge means 103 is closed and gas conduits 112b-115-111a, and
111b-111a are communicated by valve 105, 106. With this, a reaction
gas 121 consisting of the ozone-containing gas that the
concentration of ozone in oxygen is 5% and a nitrogen gas
containing the TEOS (a silicon-containing gas) and TMOP
(Trimetylphosphate (PO(OCH.sub.3).sub.3): a phosphorus-containing
gas) are introduced to a first gas discharge means 102 on the
substrate 11. The ozone-containing gas is supplied through an
O.sub.2 source 104 and ozonizer 110, a nitrogen gas containing the
TEOS is supplied through TEOS source 108, and TMOP is supplied
through TMOP source 107.
[0078] The reaction gas reacts by the temperature of the substrate
11 being increased by heating to deposit a phosphor glass film 14
on the substrate 11.
[0079] At this point of time, the flow rate of the TMOP is adjusted
in advance such that a phosphorus content in the phosphosilicate
glass film 14 becomes less than 10%.
[0080] Moreover, the film thickness of the phosphosilicate glass
film 14 is determined such that the film thickness becomes the
sufficient thickness required to delete the surface dependency and
in consideration of a width and a depth of the step (the recess) 12
and the groove (the recess) 13. That is, the sufficient thickness
required to delete the surface dependency has been found to be
approximate 10 nm or more by the experiments.
[0081] Moreover, the film thickness of the phosphosilicate glass
film 14 is influenced by the width of (the recess), whereby it is
preferable to be formed as thin as possible such that the groove
(the recess) 13 is not filled with only the phosphosilicate glass
film 14. In general, in the entire film thickness of the interlayer
dielectric film constituted by the phosphosilicate glass film 14 as
the base layer and a silicon oxide film 15 laying thereon, the film
thickness of the phosphosilicate glass film 14 is preferably
established so that the film thickness of the phosphosilicate glass
film 14 becomes sufficiently thin as compared with the film
thickness of the silicon oxide film 15. Usually, when the film
thickness of the phosphosilicate glass film 14 is approximate 100
nm, it can be recognized to be sufficiently thin. In this
embodiment, for example, a deposition time is established such that
the film thickness of the phosphosilicate glass film 14 becomes 10
nm or more and less than 100 nm.
[0082] After a lapse of the deposition time established by the
above description, the phosphosilicate glass film 14 within the
range of 10 to 100 nm in thickness is formed on the substrate 11.
Since the deposition temperature of the phosphosilicate glass film
14 is within the range of 375.degree. C. to 425.degree. C., the
phosphosilicate glass film 14 is smooth and grows in an
approximately isotropic condition regardless the type of material
exposed to the substrate 11. Moreover, the surface dependency of
the depositing film is deleted by the phosphosilicate glass film
14.
[0083] Moreover, it is effective to perform the treatment exposing
to water vapor under the condition of heating at the same
temperature as the deposition temperature in the deposition
chamber, before forming the silicon oxide film (the
silicon-containing insulating film) on the phosphosilicate glass
film 14. Therefore, the surface on the phosphosilicate glass film
14 is converted from hydrophilic to hydrophobic.
[0084] Subsequently, the TMOP is stopped and a gas supplying line
is switched to a different gas supplying line 112b-111a from the
gas supplying lines 112b-115-111a and 111b-111a through which the
reaction gas 121 containing the TMOP flew. Therefore, the ozone
containing gas containing the same concentration ozone where the
phosphosilicate glass film 14 is deposited and the TEOS (a
silicon-containing gas) continuously flow into the same deposition
chamber 101 through the second gas discharge means 103 on the
substrate 11. Moreover, the temperature of the substrate also is
kept as it is. That is, the temperature of the substrate is kept
within the temperature of 350.degree. C. to 550.degree. C.,
preferably within 375.degree. C. to 425.degree. C. in common with
the deposition temperature of the phosphosilicate glass film.
[0085] As shown in FIG. 1C, while keeping this condition, the
silicon-containing insulating film (the High O.sub.3/TEOS SiO.sub.2
film: the silicon-containing insulating film) 15 is formed on the
phosphosilicate glass film 14. At this point of time, since the
surface dependency of the depositing film in the base layer has
been deleted, the High O.sub.3/TEOS SiO.sub.2 film 15 being
deposited exhibits the significant flowability and flows into the
recess 13 narrow in width.
[0086] FIG. 2A and FIG. 2B are photography showing cross-section of
the High O.sub.3/TEOS SiO.sub.2 film 15 formed in the recess 12
wide in width and 13 narrow in width on the substrate 11. The
striped patterns observed in the High O.sub.3/TEOS SiO.sub.2 film
15 in the photography are caused by forming a different layer at
each deposition of the High O.sub.3/TEOS SiO.sub.2 film 15 with the
predetermined film thickness in order to facilitate to observe how
the depositing film deposits.
[0087] As shown in FIG. 2A, at the recess 12 wide in width,
formation of a flowing shape is recognized and moreover, as shown
in FIG. 2B, at the recess 13 narrow in width, generation of the
voids and the seams in the High O.sub.3/TEOS SiO.sub.2 film 15 of
the recess 13 can be suppressed to embed the High O.sub.3/TEOS
SiO.sub.2 film 15 into the recess 13 without clearance.
[0088] As described above, according to the embodiments of the
invention since the surface dependency of the depositing film can
be deleted by sheathing the surface of the substrate 11 with the
phosphosilicate glass film 14, the sufficient fluid ability can be
obtained, even when the High O.sub.3/TEOS SiO.sub.2 film 15 being
ready to be influenced by the surface dependency is deposited.
[0089] Since the surface dependency of the depositing film can be
deleted sufficiently by the phosphosilicate glass film 14 with the
thin film thickness, even the inside of the recess narrow in width
can be sheathed sufficiently.
[0090] Therefore, when there is the recess 13 narrow in width on
the surface of the substrate 11, the High O.sub.3/TEOS SiO.sub.2
film 15 can be embedded into the recess 13 without clearance,
without generating the voids and the seams on the High O.sub.3/TEOS
SiO.sub.2 film 15 in the recess 13.
[0091] Furthermore, since the deposition temperature at forming the
High O.sub.3/TEOS SiO.sub.2 film 15 is regulated within the range
of 350.degree. C. to 550.degree. C., preferably within the range of
375.degree. C. to 425.degree. C., on the occasion of depositing the
High O.sub.3/TEOS SiO.sub.2 film 15 by the CVD method using the
mixed gas of the O.sub.3/TEOS, the flowability of the depositing
film can be increased.
[0092] Moreover, in the embodiments of the invention described
above, although the PSG film is used as the base layer 14, the BPSG
film may be used as a substitute of the PSG film.
[0093] As the ozone-containing gas used in deposition of the
silicon-containing insulating film 15 on the base layer 14, the
High O.sub.3/TEOS SiO.sub.2 film is formed using the gas containing
the high concentration ozone such that the concentration of ozone
in oxygen is as high as 1% or more and less than 10%. However, it
can be applied also in the case of depositing the silicon oxide
film (the Low O.sub.3/TEOS SiO.sub.2 film) being not ready to be
influenced by the surface dependency using the ozone containing gas
containing the low concentration ozone such that the concentration
of ozone in oxygen is as low as less than 1%. In this case, by
using the phosphorus-containing insulating film 14 such as the
phosphosilicate glass film, in particular, penetration of moisture
and migration of alkali ions from the Low O.sub.3/TEOS SiO.sub.2
film to the substrate can be prevented except deleting of the
surface dependency of the depositing film.
[0094] Furthermore, in the above description, after depositing the
phosphosilicate glass film 14 and before forming the silicon oxide
film 15, the surface of the phosphosilicate glass film 14 is
converted to hydrophobicity by exposing to water vapor. However,
the gas discharge means used at forming the phosphosilicate glass
film 14 may be swapped with an alternate gas discharge means which
is perfectly free from the deposition of phosphorus. Whether this
or that, the substrate 11 may be moved out of the deposition
chamber to expose to the atmosphere. Therefore, the surface
dependency in the surface of the phosphosilicate glass film 14 can
be deleted.
[0095] Moreover, in the above description, although the
phosphosilicate glass film (the phosphor-containing insulating
film) 14 is formed within the range of 10 to 100 nm in thickness,
this is never limited thereto. Theoretically, it is essential only
that the film thickness of the phosphorus-containing insulating
film is less than one half of the width of the recess. Accordingly,
the upper limit of the film thickness of the phosphorus-containing
insulating film would be influenced by the width of the recess.
[0096] As described above, in the invention, the surface of the
substrate is sheathed with the phosphorus-containing insulating
film such as the phosphosilicate glass film. Therefore, the surface
dependency of the depositing film can be deleted to the substrate
to obtain the sufficient fluidity at depositing.
[0097] Moreover, the gas containing ozone of less than 10% in
oxygen is used as the ozone-containing gas used in deposition of
the silicon-containing insulating film.
[0098] That is, it is applied to the High O.sub.2/TEOS SiO.sub.2
film which is deposited using the high ozone-containing gas such
that the concentration of ozone in oxygen is 1% or more and which
is ready to be influenced by the surface dependency, or the silicon
oxide film (the Low O.sub.3/TEOS SiO.sub.2 film) which is deposited
using the low ozone containing gas that the concentration of ozone
in oxygen is less than 1% and which is not ready to be influenced
by the surface dependency.
[0099] In the case of applying to the deposition of the High
O.sub.3/TEOS SiO.sub.2 film, it is effective for deleting the
surface dependency, and in the case of applying to the deposition
of the Low O.sub.3/TEOS SiO.sub.2 film, it is effective for
preventing penetration of moisture and migration of alkali ions
from the Low O.sub.3/TEOS SiO.sub.2 film to the substrate rather
than for deleting the surface dependency.
[0100] Moreover, since the surface dependency of the depositing
film can be deleted sufficiently by using the phosphorus-containing
insulating film such as the phosphosilicate glass film, even the
inside of the recess narrow in width can be sheathed
sufficiently.
[0101] Therefore, when there is the recess narrow in width on the
surface of the substrate, the recess 13 can be embedded with the
silicon oxide film without clearance, without generating the voids
and the seams on the silicon oxide film formed in the recess.
[0102] Furthermore, since the deposition temperature at forming the
silicon-containing insulating film is regulated within the range of
350.degree. C. to 550.degree. C., preferably within the range of
375.degree. C. to 425.degree. C., on the occasion of depositing the
silicon-containing insulating film by the CVD method using the
mixed gas of the O.sub.3/TEOS, the flowability of the depositing
film can be increased.
* * * * *