JPH1164662A - Method of forming optical waveguide film - Google Patents

Abstract

(57) Abstract: A porous oxide glass film is formed by depositing oxide glass fine particles from an oxyhydrogen flame burner while moving them relative to a substrate on a table, and depositing the oxide glass particles on the substrate. An optical waveguide film forming a transparent oxide glass film by heating the porous oxide glass film by heating the porous oxide glass film. In the forming method, the thickness distribution of the oxide glass film on the substrate in the stationary state in which the relative movement is stopped is such that the local maximum value is one in a direction connecting the outlet of the burner and the outlet of the exhaust pipe. A method for forming an optical waveguide film, comprising: depositing an oxide glass film on a substrate. According to the present invention, an oxide glass film can be formed on a substrate as uniformly as possible, and the glass film thickness in the substrate has very little variation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming an optical waveguide film capable of forming an oxide glass film as uniform as possible.

[0002]

2. Description of the Related Art An optical waveguide has a structure in which an under cladding layer, a core layer, and an over cladding layer are laminated, and a substrate for forming the optical waveguide is made of Si or quartz. I have. Optical waveguide devices include beam splitters that split light into many light,
An optical switch for switching a signal to a desired line, and in the future, in an optical subscriber system, an LD and a PD together with an optical waveguide having a function of demultiplexing / combining an optical signal are provided on a Si substrate in each home.
Is expected to be introduced into the optical circuit in the ONU in which the Yamada et al. ,
“Application of planar li
ghtwave circuit platform
to hybrid integrated opti
cal WDM transmitter / receivei
ver module ", Electron. Let
t. 31 (16), 1366-1367 (1995).

[0003] The manufacturing process of an optical waveguide will be described by taking Si as an example of such an optical waveguide as a substrate. To manufacture an optical waveguide on a Si substrate, first, a glass having a thickness of about 20 µm to be an under clad is formed. After forming a layer, a core layer through which light is guided is formed thereon, and the core layer is processed into a light waveguide pattern by lithography and anisotropic etching. This is done by forming layers. As a means for forming these glass layers, a flame deposition method, an electron beam evaporation method, a sputtering method, a plasma CVD method, and the like are known, but a flame deposition method is generally used for producing a glass film having a thickness of several tens of μm. Have been.

[0004] Flame Hydrolysis
is Deposition (FHD) method is described in, for example, M. et al. Kawachi, "Silica waveguii
des on silicon and theair
application to integrated
-Optic components ", Optica
l and Quantum Electronics
22, 391-416 (1990), an apparatus such as Si, Ge, B
A halide such as r or P is supplied to an oxyhydrogen burner to generate glass fine particles, which are deposited on a substrate placed on a table to form a porous glass fine particle film. This is a method of producing a transparent glass film by sintering at a temperature of 1200 to 1400 ° C.

In FIG. 1, reference numeral 11 denotes a rotary table, on which a plurality of substrates 12 are arranged along the circumferential direction on the outer peripheral side, and an oxyhydrogen flame burner 13 and a plurality of substrates 12 are arranged at a predetermined distance above the substrate 12. An exhaust pipe 14 is provided.
Then, the oxide glass particles are deposited from the burner 13 on the substrate 12 on the table 11 to form a porous oxide glass film, while the oxide glass particles not deposited on the substrate 12 are exhausted from the exhaust pipe 14. I do. In this case, the substrate 12 and the burner 13 are relatively moved in order to uniformly deposit the oxide glass fine particles on the substrate 12, and in the case of FIG.
Is moved while moving along the radial direction of the table 11. At this time, generally, the exhaust pipe 14 is moved as the burner 13 moves.

The size of a substrate on which a glass film is formed is generally 4 inches (= 10 cm) in diameter. Considering that a plurality of devices are formed on one substrate, Then, it is desired that the in-plane film thickness and the refractive index be uniform in order to reduce the variation between devices. In particular, regarding the film thickness, the apparatus shown in FIG. 1 is required to be deposited in the same manner on the substrate surface. For example, in FIG. 1, a plurality of substrates are placed on the outer periphery of a turntable having a large radius. However, if the angular speed of rotation of the table is always constant, the speed changes between the inside and the outside of the substrate. If the oxyhydrogen flame burner is reciprocated at a constant speed in such a situation, the deposition time changes between the inside and the outside of the substrate, and there is a problem that the in-plane film thickness distribution becomes large. In order to avoid such a situation, for example, JP-A-5-301721 and JP-A-8-2622
Japanese Patent Application Laid-Open No. 52-52139 describes a method of changing the moving speed of an oxyhydrogen flame burner at a substrate position, and Japanese Patent Application Laid-Open No. 7-20338 discloses a method of changing the rotation speed of a table according to the position of a burner.

However, even if the movement speed of the oxyhydrogen flame burner or the rotation speed of the turntable is adjusted as described above in a form in which the substrate is placed on a flat table as shown in FIG. In the glass film having a thickness of 20 μm formed as described above, a thickness variation of 1 μm or more was observed in the plane. The cause is a step corresponding to the thickness of the substrate between the table and the substrate, and the flow of the oxyhydrogen flame and the oxide glass fine particles emitted from the oxyhydrogen flame burner is located between the step and the center of the substrate. Things could be different. That is, near the center of the substrate, the flow from the oxyhydrogen flame to the exhaust pipe for removing excess oxide fine particles out of the system is in a laminar flow state, whereas when the oxyhydrogen flame hits the edge of the substrate, it flows at the stepped portion. Is turbulent, resulting in a turbulent flow state and a flow state different from that near the center. For this reason, the state of deposition changes near the center of the substrate and near the outer periphery, and a film thickness variation occurs in the substrate surface.

In order to avoid such a situation, Japanese Patent Laid-Open Publication No.
JP-A-27133 and JP-A-5-264838 describe that a recess is provided in a table in advance in order to eliminate a step between a table and a substrate.

However, when the present inventors conducted experiments, it was found that when a glass film having a thickness of 20 μm was formed, the variation in the film thickness on the substrate surface was about 1 μm, and the variation between samples was large. This means that there are other causes of the film thickness distribution, and if this is not solved, there is a problem that the yield decreases and the cost increases.

[0010] The present invention is an improvement of the above-mentioned circumstances, in which a porous glass film is formed by relatively moving an oxyhydrogen flame burner and a substrate to deposit glass fine particles.
It is an object of the present invention to provide a method for forming an optical waveguide film capable of forming a glass film having a uniform film thickness by reducing variation in the film thickness distribution in a substrate surface.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an oxyhydrogen flame burner in which oxide glass particles are deposited while moving relative to a substrate on a table. Forming a porous oxide glass film by heating, and having a porous oxide glass film forming step of discharging oxide glass fine particles not deposited on the substrate through an exhaust pipe, and heating the porous oxide glass film. In the method of forming an optical waveguide film by forming a transparent oxide glass film, the film thickness distribution of the oxide glass film on the substrate in the stationary state where the relative movement is stopped is reduced by the discharge port and the exhaust port of the burner. Provided is a method for forming an optical waveguide film, wherein an oxide glass film is deposited so that a maximum value becomes one in a direction connecting an exhaust port of a tube. In this case, it is preferable that the position where the film thickness distribution becomes maximum is located on the burner side from the midpoint of a straight line connecting the jet port of the burner and the exhaust port of the exhaust pipe. Further, it is preferable to use oxygen as a gas for transporting the glass forming raw material to the oxyhydrogen flame burner.

That is, the present inventor has made various studies on overcoming the above-mentioned problems of the prior art and forming a glass film uniformly on a substrate. First, when the film thickness distribution is large, what kind of film thickness distribution is shown from the oxyhydrogen flame burner to the exhaust pipe is performed. The film thickness distribution when the test was performed was examined. The results are shown in FIG. As the substrate, a Si substrate having a diameter of 10 cm and a thickness of 1 mm is used, and the horizontal axis in FIG. 2 represents the substrate diameter. The positional relationship between the oxyhydrogen flame burner, the substrate, and the exhaust pipe is as shown in FIG. 4, and the oxyhydrogen flame burner is located at a position of 0.5 cm on the horizontal axis in FIG. Located in the location. The angle between the oxyhydrogen flame burner and the normal direction is 70 °, and the height of the burner from the substrate is about 2 cm.

The distribution shown in FIG. 2 represents a film thickness distribution in a direction parallel to a line connecting the center of the outlet of the oxyhydrogen flame burner and the center of the outlet of the exhaust pipe. In this figure, the oxyhydrogen flame burner is located on the left and the exhaust pipe is located on the right. The film thickness is maximum in the vicinity of the position where the flame from the oxyhydrogen flame burner hits the substrate (position of 3 cm on the horizontal axis in FIG. 2), but another location on the exhaust pipe side where the film thickness is maximum Is seen.

Under the condition that the film thickness distribution at the time of the static deposition is as shown in FIG. 2, the reciprocating motion is performed while maintaining the positional relationship between the oxyhydrogen flame burner and the exhaust pipe constant, and glass fine particles are spread over the substrate surface. When deposited, the film thickness at the center of the substrate is 20
The variation in the in-plane film thickness was 1 μm (± 2.5%) with respect to μm. Further, when several samples were prepared under the same conditions, the film thickness distribution was ± 1.5% to ± 3.0% (film thickness variation of 0.6 to
1.2 μm).

The film thickness distribution shown in FIG. 2, but is obtained by using Ar as a gas species for transporting a raw material gas to the oxyhydrogen flame burner, the O ₂ is used as carrier gas species of the source gas, similarly FIG. 3 shows the film thickness distribution in the direction connecting the oxyhydrogen flame burner and the exhaust pipe when the deposition was performed with both the oxyhydrogen flame burner and the substrate stationary and the glass was made transparent. At this time, the positional relationship between the oxyhydrogen flame burner, the substrate, and the exhaust pipe is the same as in FIG. Unlike FIG. 2, the maximum value of the film thickness exists at the position where the flame from the oxyhydrogen flame burner hits the substrate, but the exhaust pipe side does not show any increase in the film thickness, but decreases monotonously. Just do it. When glass particles were deposited over the substrate surface under these conditions, the film thickness variation in the surface was 0.4 μm (± 1%) with respect to the film thickness of 20 μm at the center of the substrate. When several samples were prepared under the same conditions, the film thickness distribution was from ± 0.6% to ± 1.
2% (film thickness variation of 0.25 to 0.5 μm), and the variation of the in-plane film thickness and the variation between samples were considerably reduced.

Considering the cause of the film thickness distribution, FIG.
The existence of the film thickness distribution maximum on the middle and right sides was considered. In other words, the thickness of the film becomes maximum at the position where the flame emitted from the oxyhydrogen flame burner directly hits the substrate, but the linear velocity of the gas emitted from the burner is high, so that it is hardly affected by the external atmosphere. At the position on the right where the film thickness is maximal, the flow of the flame and glass fine particles that once hit the substrate is focused by the exhaust pipe, so that the exhaust pressure fluctuates and the substrate is heated to a certain temperature. Susceptible to disturbances such as thermal fluctuations of heaters installed in Therefore, under the condition showing the film thickness distribution at rest as shown in FIG. 2, the distribution shape, especially the state of the maximum value on the right side, changes depending on the deposition position, and finally, the film thickness distribution in the plane is generated. it was thought. Therefore, a condition that does not have the film thickness distribution at rest as shown in FIG.
It has been found that by depositing under conditions having a film thickness distribution at rest as shown in FIG. 2, the influence of disturbance can be reduced, the film thickness distribution can be kept small, and the variation between samples can be kept small. It has been found that the method of depositing an object glass film is effective.

The method of forming an optical waveguide film according to the present invention will now be described in more detail. The method of forming an optical waveguide film according to the present invention is characterized in that oxide glass fine particles are deposited from an oxyhydrogen flame burner while being moved relatively to a substrate on a table. Forming a porous oxide glass film and discharging the fine particles of oxide glass not deposited on the substrate through an exhaust pipe, and heating the porous oxide glass film. A transparent oxide glass film is formed by the method described above, and the glass forming raw material, the oxide glass fine particle deposition apparatus, and the like used in such a method may be the same as a known ordinary method. Gas flow rate when forming a glass thin film, raw material supply amount, and substrate,
The conditions such as the position of the burner and the exhaust pipe are set such that the film thickness distribution in the direction parallel to the direction connecting the burner jet port and the exhaust pipe exhaust port formed when the substrate and the burner are stationary without moving relatively is two or more. The porous glass film is formed under the condition that there is no maximum value and the maximum value is one.

As described above, the reason why the film thickness varies in the plane is that the film thickness is large at a position close to the exhaust pipe as shown in FIG. 2, and this is caused by disturbance such as fluctuation in exhaust pressure and thermal fluctuation. It is considered that the film thickness is likely to fluctuate and, when deposited over the entire substrate surface, may result in an increase in the in-plane film thickness distribution. Therefore, in order to reduce the film thickness distribution, the film at rest shown in FIG. In the thickness distribution, the contribution of the left side film local maximum that is relatively unaffected by disturbance is increased, and the contribution of the right side local maximum is reduced, that is, the distribution shape such that the film thickness distribution does not take the local maximum value near the exhaust pipe. The deposition is carried out under the conditions such as the geometrical arrangement of the burner and the exhaust pipe, the type of gas, the flow rate, and the displacement.

Under these conditions, it is preferable to use oxygen as the gas for transporting the glass-forming raw material to the oxyhydrogen flame burner, and to use O ₂ gas for the raw material for forming the glass film.
By doing so, the film thickness does not have a local maximum value in the vicinity of the exhaust pipe, but has a distribution that monotonically decreases. This is apparent from the results of FIGS. 2 and 3, and the result of FIG. 3 showing the film thickness distribution at rest at this time is different from FIG. 2 in that the increase in the film thickness on the exhaust pipe side is suppressed. You can see that.

Under the condition that the film thickness distribution at rest is shown in FIGS. 2 and 3, an example of the film thickness distribution after depositing and sintering the oxyhydrogen flame burner and the substrate is shown. It is shown in Table 1.

[0021]

[Table 1]

The position where the film thickness distribution is maximized is
A straight line L connecting the burner ejection port and the exhaust port of the exhaust pipe, particularly a straight line L connecting the ejection port center and the exhaust port center in FIG.
Is located closer to the burner than the midpoint L / 2, more preferably near the position P where the jet flows from the burner to the substrate, whereby a glass film having a uniform thickness can be formed more reliably.

That is, FIG. 5 shows a change in the film thickness distribution at rest when the carrier gas of SiCl _{4 as} the glass raw material gas is O ₂ and the flow rate is changed. At this time, the arrangement of the oxyhydrogen flame burner, the substrate, and the exhaust pipe is the same as the arrangement of FIG. Carrier gas flow rate is 50cc / min, 200
cc / min and 250 cc / min are changed. In all cases, the maximum of the film thickness distribution is one, but the position where the maximum is obtained is different. That is, as the supply amount of SiCl ₄ increases, the maximum position shifts to the exhaust pipe side. The burner and substrate are moved under these conditions,
Table 2 shows the results after the vitrification.

[0024]

[Table 2]

As can be seen from the results in Table 2, SiCl ₄
When the supply amount of the film is large, the maximum film thickness during the static deposition is 1
Despite the presence of only a few parts, the distribution of the film thickness is large. This is presumably because the position where the film thickness is maximum shifts to the exhaust pipe side as compared with the distribution when the supply amount is small, and the film thickness takes the maximum value at a position that is easily affected by disturbance. Therefore, even if the maximum value of the film thickness at the time of static deposition is only at one location, it is important at which position the maximum value is obtained in the in-plane film thickness distribution when the final scan is performed. That is, the maximum value of the film thickness to less susceptible position the influence of thermal fluctuation and exhaust pressure fluctuation disturbance is not sufficient if, as is the guide, distribution during SiCl ₄ carrier gas flow rate of 50 cc / min 5 There is no problem at the position where the film thickness is maximum, and the middle point of the burner and the exhaust pipe is located at 4 cm on the horizontal axis in FIG. 5 from the positional relationship between the burner and the exhaust pipe shown in FIG. Therefore, the location where the maximum value of the film thickness during static deposition is
It is desirable to be on the burner side from the midpoint on the line connecting the exhaust pipe and the burner.

In order to achieve such a state, it is preferable that the flow rate of the glass forming raw material or the flow rate of O ₂ (carrier gas) for transporting the glass raw material is ₂₀ to 100 cc / min.

The height of the burner from the substrate is 1 to 4
cm, the angle to the normal direction of the burner is 60 to 80.
°, the distance between the burner and the exhaust pipe is 6 to 8 cm, and the stroke length of the burner and the exhaust pipe during reciprocation is 14 to 18 c
m, the moving speed is 0.5 to 3 cm / min, the rotation speed of the table is 0.5 to 10 rpm, and the flow rate of H ₂ is 4 to 8 L /
The flow rates of min and O ₂ can be 4 to 8 L / min, and the flow rates of Ar can be 0.5 to ₂ L / min. Conditions can be set such that the maximum value is one in the direction connecting the burner outlet and the exhaust pipe outlet.

[0028]

According to the present invention, the oxide glass film can be formed as uniformly as possible on the substrate, and the variation in the glass film thickness within the substrate is very small.

[0029]

EXAMPLES The present invention will be described below in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Example 1 The deposition of oxide glass fine particles on a substrate was performed as follows. A plurality of Si substrates having a diameter of 10 cm and a thickness of 1 mm were mounted on the outer periphery of a rotary table having a diameter of 80 cm. At this time, the temperature of the substrate was heated to about 600 ° C. by a heater provided below the turntable.
The glass material was supplied to the oxyhydrogen flame burner while rotating the table on which the substrate was placed, and the glass particles were deposited on the substrate while the burner was reciprocated in the radial direction of the table. The deposition conditions were such that when the deposition was performed at rest, the film thickness distribution in the direction connecting the burner and the exhaust pipe had the shape shown in FIG. The height of the burner from the substrate is 2cm
The distance between the burner and the exhaust pipe was 6.6 cm, and the angle with respect to the normal direction of the burner was 70 °. SiCl ₄ , BBr ₃ and POCl ₃ are supplied as glass raw materials, and the supply amount of each is 50 cc / min and 20 cc / mi.
n and 20 cc / min. O ₂ was used as a carrier gas at this time. These glass source gases are supplied from the center of the quadruple tube burner, and the flow rates of other gases are as follows: H ₂ = 8 L / min, O ₂ = 6 L / min, Ar
= 1 L / min. The deposition time when obtaining the distribution of FIG. 3 is 10 seconds. The burner reciprocates while rotating the substrate, and the exhaust pipe also reciprocates in conjunction with the burner so as not to change the positional relationship with the burner. The stroke length of the burner and the exhaust pipe during the reciprocating motion was 16 cm, the moving speed was 1 cm / min, and the rotation speed of the table was 5 rpm. The deposition was performed for about 90 minutes, and after the deposition was completed, the substrate was taken out and vitrified in an electric furnace. The atmosphere during the treatment is a mixed atmosphere of He and O ₂ , and the respective flow rates are He = 2.5 L / min, O ₂
= 0.3 L / min. The processing temperature was 1350 ° C., and the temperature was maintained for 2 hours. The thickness distribution of the vitrified sample was measured by a prism coupling method using a model 2010 manufactured by Metricon. FIG. 6 shows an example of the measured film thickness distribution. Maximum thickness 21.0164 μm, minimum thickness 20.65
The thickness was 62 μm, the thickness variation width was 0.3602 μm, and the thickness distribution was ± 0.9%.

FIG. 7 shows the transition of the film thickness distribution between the samples when the production and measurement of the samples were repeated under the same conditions. FIG. 7 shows a change in the film thickness distribution of the 14 samples manufactured, which is ± 0.8% at the minimum and ± 1.2% at the maximum, and is stable at a film thickness distribution of about ± 1%. It can be seen that it has been manufactured.

Comparative Example 1 A comparison with Example 1 was made.
, SiCl _FourUsing Ar as carrier gas for
Was. The method is the same as that described in Example 1, except that the static
Connecting the burner and exhaust pipe when depositing
2 shows the shape of FIG. burner
And the arrangement of the exhaust pipe are the same as those in the first embodiment.
_FourIs 50 cc / min, other deposition conditions, firing
The setting conditions were exactly the same. Transparent vitrified sample
FIG. 8 shows an example of the measurement of the film thickness distribution. Maximum film thickness 2
0.7714 μm, minimum thickness 19.5264 μm, thickness
The fluctuation width is 1.245 μm, and the film thickness distribution is ± 3.1%.
there were. That is, the carrier gas is changed to O_TwoChange from to Ar
Only, the film thickness variation width is 0.3602 μm → 1.245 μm
m, the film thickness distribution became worse from ± 0.9% to ± 3.1%.
The contribution of the film thickness deposited near the exhaust pipe
It is recognized whether the cloth is bad.

Next, FIG. 9 shows the transition of the film thickness distribution between the samples when the production and measurement of the samples were repeated under the same conditions. FIG. 9 shows the change in the film thickness distribution of the 14 samples manufactured, with the minimum being ± 1.5% and the maximum being ± 3.1%.
It can be seen that the value of the film thickness distribution is larger than that of FIG. In addition, the film thickness distribution fluctuates greatly between samples, and it cannot be said that the film is manufactured stably as compared with FIG. Therefore, FIG.
In the film thickness distribution at rest, it is possible to confirm how much the film thickness maximum on the right side affects the size of the film thickness distribution and the variation between samples.

[Reference Example] SiCl _FourAs a carrier gas
O_TwoIs used, but the film thickness when the flow rate is increased
I checked the cloth. The carrier gas flow rate is 250 cc / min
And Burner and exhaust pipe during stationary deposition
5 is 250 cc in FIG.
/ Min. Burners and exhaust pipes
Are the same as those described in the first embodiment. Heap
The sintering conditions were almost the same as in Example 1, except that the transparent gas
It is performed so that the film thickness after lasing becomes about 20 μm.
Therefore, the deposition time was set to about 20 minutes. Transparent glass in this condition
FIG. 10 shows an example of the measurement of the film thickness distribution of
You. Maximum film thickness 20.2165 μm, minimum film thickness 19.17
13 μm, and the thickness variation width was 1.0452 μm.
The fabric was ± 2.7%. In other words, the film thickness distribution at rest
Even if there is only one place where the film thickness becomes maximum,
Is close to the exhaust pipe on the line connecting the burner and the exhaust pipe
It can be seen that the in-plane film thickness distribution is worse at the position
You. Therefore, in the film thickness distribution at rest,
The maximum thickness is actually deposited over the entire substrate surface.
It is important to keep the film thickness distribution when
Call

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an apparatus for forming a glass fine particle film by a flame deposition method.

FIG. 2 is a graph showing a film thickness distribution during static deposition in a conventional method.

FIG. 3 is a graph showing an example of a film thickness distribution during static deposition in the method of the present invention.

FIG. 4 is an explanatory diagram showing a positional relationship between a burner and an exhaust pipe with respect to a substrate.

FIG. 5 is a graph showing a film thickness distribution at the time of static deposition when the flow rate is variously changed using oxygen gas as a carrier gas.

6A and 6B show a film thickness distribution in an example, where FIG. 6A is an explanatory diagram of a substrate measurement position, FIG. 6B is a film thickness distribution graph in the Y-axis direction, and FIG. is there.

FIG. 7 is a graph showing a transition of a film thickness distribution between samples in an example.

8A and 8B show a film thickness distribution in a comparative example, wherein FIG. 8A is an explanatory diagram of a substrate measurement position, FIG. 8B is a film thickness distribution graph in the Y-axis direction, and FIG. is there.

FIG. 9 is a graph showing a change in film thickness distribution between samples in a comparative example.

10A and 10B show a film thickness distribution in a reference example, wherein FIG. 10A is an explanatory diagram of a substrate measurement position, FIG. 10B is a film thickness distribution graph in the Y-axis direction, and FIG. 10C is a film thickness distribution graph in the X-axis direction. is there.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Rotary table 12 Substrate 13 Oxy-hydrogen flame burner 14 Exhaust pipe

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazuo Kamiya 2-13-1, Isobe, Annaka-shi, Gunma Shin-Etsu Kagaku Kogyo Co., Ltd.Precision Functional Materials Research Laboratories (72) Inventor Shinji Makikawa Annaka-shi, Gunma 2-13-1 Isobe Shin-Etsu Chemical Industry Co., Ltd.

Claims (3)

[Claims] 1. A porous oxide glass film is formed by depositing oxide glass fine particles from an oxyhydrogen flame burner while moving them relatively to a substrate on a table, and an oxide not deposited on the substrate. A method for forming an optical waveguide film, comprising: forming a transparent oxide glass film by heating the porous oxide glass film, the method further comprising: The oxide glass film is formed such that the film thickness distribution of the oxide glass film on the substrate in a stationary state in which the relative movement is stopped has a maximum value in the direction connecting the outlet of the burner and the outlet of the exhaust pipe. Forming an optical waveguide film. 2. The light guide according to claim 1, wherein the position where the film thickness distribution is maximized is located on the burner side with respect to a midpoint of a straight line connecting the outlet of the burner and the outlet of the exhaust pipe. A method for forming a waveguide film. 3. The method for forming an optical waveguide film according to claim 1, wherein the gas for conveying the glass forming raw material to the oxyhydrogen flame burner is oxygen.