JP2005154827A - Glass film manufacturing method and waveguide manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass film manufacturing method for forming a glass film having the same composition and the same thickness on upper and lower sides of a substrate. <P>SOLUTION: In the glass film manufacturing method in which an upper electrode 18 and a lower electrode 16 are arranged in a reaction vessel 11 facing each other, high voltage is applied to the electrodes 16 and 18, the electrodes 16 and 18 are heated, gas to form raw glass is introduced into the vessel 11, and a glass thin film is formed on a substrate 25 in the plasma atmosphere, the substrate is arranged on the lower electrode 16 via a gap, an open space 26 is formed on a lower side of the substrate 25 and a glass film is deposited on both sides of the substrate 25. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a glass film manufacturing method for forming a glass film on a substrate, and a waveguide manufacturing method for processing and forming the glass film.

  In the conventional glass film manufacturing apparatus 60 shown in FIG. 4, an upper electrode 63 with a heater and a lower electrode 64 are disposed oppositely in a reaction vessel 61, and a high frequency power supply 66 is connected between the electrodes 63, 64. The substrate 68 is disposed on the lower electrode 64. Further, an exhaust device 62 that keeps the inside of the reaction vessel 61 in a vacuum state and a supply pipe 67 that supplies a raw material gas and the like are connected.

The glass film is formed by heating an upper electrode 63 and a lower electrode 64, applying high-frequency power, and heating an alcoholate-based liquid source ([Si (OC ₂ H ₅ )) in a thermostat 72. _4] 69 passes through the _{[Ge (OCH 3) 4]} 70, [P (OCH 3) 3] O 2 gas 71, etc.) is supplied through the gas and O ₂ tube 73 was vaporized, the supply pipe 67 Then, it is sprayed from the gas shower 65 onto the substrate 68 and undergoes a thermal decomposition reaction in a plasma atmosphere, and a glass film is formed on the substrate 68.

  Reference numeral 74 denotes a side surface protection plate for forming a uniform glass film on the substrate 68.

JP-A-11-288289 JP 2001-348236 A JP 2002-141342 A

  However, the above glass manufacturing method has the following problems.

  (1) In the above manufacturing method, the film can be formed only on one side of the substrate. Therefore, when forming glass films on both sides of the substrate, after forming the glass film on one side (surface) of the substrate, break the inside of the reaction vessel once to atmospheric pressure, place the substrate upside down, A glass film had to be formed on the back surface under vacuum.

  However, this method has a problem that it takes time to form a glass film.

  Furthermore, since the film is separately formed on the front surface and the back surface of the substrate, the characteristics (optical, thermal, mechanical characteristics, etc.) between the front and back glass films may be different.

  In addition, when the substrate is turned over on the lower electrode, the glass film on the substrate surface is damaged or contaminated.

  (2) When a glass film is formed on the substrate surface, the substrate is warped due to the difference in thermal expansion coefficient between the glass film and the substrate. When the warped substrate is heat-treated at a high temperature, the warpage of the substrate increases.

  When a warped glass film is processed to form a waveguide, a waveguide having a large loss difference between the TE mode and the TM mode and having a large so-called polarization dependency is obtained.

  Further, the warpage of the substrate causes a distribution in the dimension of the exposure pattern within the substrate surface in the photolithography process, and there is a problem that the processing dimensional accuracy is further deteriorated in the subsequent dry etching process.

  When the thermal expansion coefficient and the softening temperature of the substrate and the glass film are greatly different, the above problem occurs remarkably, so that the substrate is warped when the glass film is first formed on the substrate surface. Further, even if a glass film is formed on the back surface of the warped substrate, the generated warp does not return.

  The above problem also occurs remarkably when the relative refractive index difference between the core layer and the clad layer of the waveguide is large.

  Accordingly, an object of the present invention is to solve the above problems and provide a glass film manufacturing method in which glass with the same composition and the same film thickness is formed on both upper and lower surfaces of a substrate.

  In order to achieve the above object, the invention according to claim 1 is arranged such that an upper electrode and a lower electrode are arranged to face each other in a reaction vessel, a high voltage is applied to the electrode, the electrode is heated, In a glass film manufacturing method in which a gas is introduced into a container and a glass thin film is formed on the substrate in a plasma atmosphere, the substrate is disposed through a gap on the lower electrode and an open space is formed on the lower surface of the substrate And it is the manufacturing method of the glass film which forms a glass film in the upper and lower surfaces of the board | substrate.

  The invention according to claim 2 is the method for producing a glass film according to claim 1, wherein the height of the gap is in the range of 2 mm to 15 mm.

  A third aspect of the present invention is the glass film manufacturing method according to the first or second aspect, wherein the substrate fixing member is provided on the lower electrode so as to be positioned on the outer periphery of the substrate disposed thereon.

  According to the invention of claim 4, the substrate fixing member is formed in a columnar shape, and at least three substrate fixing members are provided on the outer periphery of the substrate, and the substrate is placed on the columnar substrate fixing member to form a film. To 3. The method for producing a glass film according to any one of 3 to 4.

A fifth aspect of the present invention is the glass film manufacturing method according to any one of the first to fourth aspects, wherein the source gas is a gas obtained by vaporizing an alcoholate liquid source or a SiH ₄ gas.

  The invention of claim 6 is the method for producing a glass film according to any one of claims 1 to 5, wherein a plurality of glass films having different glass compositions are laminated on both surfaces of the substrate.

  The invention according to claim 7 is the method for producing a glass film according to any one of claims 1 to 6, wherein a substrate made of glass, a semiconductor, ceramics and a polymer material is used as the substrate.

  The invention of claim 8 is the method for producing a glass film according to any one of claims 1 to 7, wherein the substrate is used in which at least one of both surfaces of the substrate is polished in a mirror state.

  The invention of claim 9 is the method for producing a glass film according to any one of claims 1 to 8, wherein the electrode and the lower electrode are heated to the same temperature within a range of 300 to 600 ° C.

The invention of claim 10 introduces a gas obtained by vaporizing Si (OC ₂ H ₅ ) ₄ into a source gas, a gas obtained by mixing O ₂ gas and C ₂ F ₆ gas at a predetermined mixing ratio, and adds fluorine. The glass film manufacturing method according to claim 1, wherein a glass film is formed.

  Invention of Claim 11 is a manufacturing method of the glass film which laminates | stacks the glass layer whose refractive index is higher than the glass film on the upper layer of the glass film manufactured by the manufacturing method of Claim 10.

The invention of claim 12 is a step of high-temperature heat-treating the glass film formed by the glass film manufacturing method of any one of claims 1 to 11 at a temperature in the range of 800 ° C to 1350 ° C;
This is a method for manufacturing a waveguide comprising a step of forming a waveguide pattern by photolithography and dry etching.

According to a thirteenth aspect of the present invention, a gas obtained by vaporizing Si (OC ₂ H ₅ ) ₄ on the waveguide pattern on the upper surface of the substrate and the glass film on the lower surface of the substrate formed by the waveguide manufacturing method according to the twelfth aspect and O This is a waveguide manufacturing method in which a mixed gas of ₂ gas and C ₂ F ₆ gas is introduced at a predetermined mixing ratio to form a glass film to which fluorine is added.

  A fourteenth aspect of the present invention is a waveguide manufacturing method in which a substrate on which a waveguide formed by the waveguide manufacturing method according to the thirteenth aspect is formed is subjected to high-temperature heat treatment within a temperature range of 800 ° C. to 1350 ° C.

  According to the present invention, an excellent effect that glass films having the same composition and the same film thickness can be formed on the upper and lower surfaces of the substrate is exhibited.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a schematic view of a manufacturing apparatus 1 used in the glass film manufacturing method of the present embodiment.

  The manufacturing apparatus 1 is provided in a clean booth 10 maintained in a class 100 by a clean unit 40.

  Inside the reaction vessel 11, an upper electrode 18 and a lower electrode 16 are arranged to face each other at a predetermined interval. The lower electrode 16 is provided with a heater capable of heating up to a maximum temperature of 500 ° C. (not shown), and the upper electrode 18 is provided with a heater capable of heating up to a maximum temperature of 400 ° C. (not shown).

  Large-capacity exhaust devices 13 and 13 are provided at the bottom of the reaction vessel 11 via two exhaust ports 12 and 12, respectively. The large capacity exhaust device 13 includes a mechanical booster pump 14 and a dry pump 15.

  The displacement of the mechanical booster pump 14 is 8200 l / min or more, and the displacement of the dry pump 15 is 1200 l / min or more.

  The lower electrode 16 and the upper electrode 18 are connected to a high frequency power source 22 for applying high frequency power via lead wires 21 and 21. On the lower electrode 16, at least one substrate 25 (three in the figure) is disposed via a gap 17 formed by the substrate fixing member 24, and an open space 26 is formed between the lower electrode 16 and the substrate 25. ing.

  Here, the open space 26 formed on the lower surface of the substrate 25 will be described.

  As shown in FIG. 2, the substrate fixing member 24 is formed in a columnar shape and is provided on the outer periphery of the substrate 25 to fix the substrate 25 in parallel. Each substrate fixing member 24 is provided at three locations where the outer periphery of one substrate 25 is substantially equally divided, thereby fixing the substrate 25.

  As a result, the substrate 25 is disposed on the lower electrode 16 via the gap 17, and an open space 26 is formed on the lower surface of the substrate 25. The gap 17 between the substrate 25 and the lower electrode 16 is preferably 2 mm to 15 mm.

  When the gap 17 is smaller than 2 mm, it is difficult for plasma to wrap around the lower surface of the substrate 25 during the glass film formation. Furthermore, the gas introduced into the reaction vessel 11 also hardly flows around the lower surface of the substrate 25, and the composition and film thickness of the glass films formed on the upper surface and the lower surface of the substrate 25 are different. On the other hand, if the gap is larger than 15 mm, the difference in the composition and optical characteristics of the glass film in the plane between the upper surface of the substrate 25 and the lower surface of the substrate 25 increases, and the composition of the glass film formed on the upper surface and lower surface of the substrate. The film thickness distribution is non-uniform.

  Therefore, the width of the gap is preferably in the range of 2 to 15 mm.

  In the present embodiment, three columnar substrate fixing members 24 are provided on the lower side of the substrate 25 in one substrate 25, but four or more may be used. The substrate fixing member 24 may include a mechanism for sandwiching the substrate 25 and may be fixed to the upper side (the upper electrode 18, the upper wall, etc.) or the side wall of the reaction vessel 11 to hold the substrate 25. At that time, the substrate fixing member 24 is not limited to the columnar shape, but may be two or more.

  On the other hand, a shower disk 19 for injecting gas into the reaction vessel 11 is provided on the lower electrode 16 side of the upper electrode 18. A large number of injection ports 20 are formed in the shower disc 19, and a gas supply pipe 23 for supplying the gas to be injected is connected. The gas supply pipe 23 is provided with a tape heater 45 for setting the gas passing through the gas supply pipe 23 to the same temperature.

The reaction container 11 is adjacent to a reaction container front chamber 42 through which a substrate 25 is taken in and out through a substrate entrance 41. The reaction vessel front chamber 42, the gas shower 44 blowing N ₂ gas is provided on the substrate surface, N ₂ gas pipe 43 for introducing the N ₂ gas is connected to the gas shower 44.

The gas introduced into the reaction vessel 11 is a gas obtained by vaporizing an alcoholate liquid source that is a raw material for the glass film, and a gas such as O ₂ , N ₂ , NH ₃ , C ₂ F _6, etc. that reacts with the gas. Is used.

As the alcoholate-based liquid source, a Si-based liquid source 28 such as [Si (OC ₂ H ₅ ) ₄ ] is used and heated and vaporized in a thermostatic chamber 29. The temperature of the thermostatic chamber 29 was 75 ° C. higher than the melting point of the liquid source 28 and lower than the boiling point. A Si-based gas supply pipe 27 that supplies gas obtained by vaporizing the Si-based liquid source 28 is connected to the gas supply pipe 23.

In addition to the Si-based liquid source 28, a Ge-based liquid source 31 such as [Ge (OCH ₃ ) ₄ ] and a P-based liquid source 34 such as [P (OCH ₃ ) ₄ ] may be used. , 35 to heat and vaporize. A Ge-based gas supply pipe 30 that supplies gas vaporized from the Ge-based liquid source 31 and a P-based gas supply pipe 33 that supplies gas vaporized from the P-based liquid source 34 are also connected to the gas supply pipe 23. .

_{Also, O 2, N 2, NH} 3, C 2 F 6 and O ₂ gas supply pipe 36 for supplying to the reaction vessel 11, respectively, N ₂ gas supply pipe 37, NH ₃ gas supply pipe 38, C ₂ F ₆ gas supply A pipe 39 is connected to the gas supply pipe 23.

  Next, a film forming method (manufacturing method) of the glass film will be described.

  The reaction vessel 11 in which the substrate 25 is disposed is evacuated to a high vacuum by the large capacity exhaust devices 13, 13, high frequency power is applied to the lower electrode 16 and the upper electrode 18 by the high frequency power source 22, and the upper electrode 18 and the lower electrode 16 is heated.

  The applied high frequency power is 13.56 MHz and 1 kW, and the heating temperature of the upper electrode 18 and the lower electrode 16 is 300 to 600 ° C.

  The degree of vacuum in the reaction vessel 11 is preferably several Pa to several tens Pa. If the degree of vacuum is low, the amount of the glass film formed on the lower surface of the substrate 25 is reduced, and a non-uniform glass film tends to be formed. If the degree of vacuum is too high, the film forming rate is reduced and the glass film is oxygen-defected. This is because it is easy.

Next, steam, O ₂ gas, and C ₂ F ₆ gas, which are vaporized by heating the Si-based liquid source 28 to 75 ° C. in the thermostat 29, are mixed in the gas supply pipe 23 heated by the tape heater 45. Superposed and introduced into the reaction vessel 11. The introduced gas is uniformly diffused in the reaction vessel 11 so as to be sprayed from the outlet 20 of the shower disk 19 to the substrate 25.

The O ₂ gas is flowed in order to cause a sufficient thermal decomposition reaction of the gas obtained by vaporizing the Si-based liquid source 28 in a plasma atmosphere, and the C ₂ F ₆ gas is F (fluorine) in the SiO ₂ glass film. Used to add.

The temperature in the gas supply pipe 23 is preferably in the range of 80 ° C to 120 ° C. When the temperature in the tube is higher than 120 ° C., hydrolysis reaction occurs in the tube, and glass fine particles adhere to the tube. When the temperature is lower than 80 ° C., adhesion due to liquefaction of the Si-based liquid source 28, C ₂ F ₆ gas, This is because the liquid reaction occurs.

In the reaction vessel 11, plasma is generated between the upper electrode 18 and the lower electrode 16 by high-frequency power and kept at a high vacuum, so that F is formed on the upper surface and the lower surface of the substrate 25 by a thermal decomposition reaction in a plasma atmosphere. A glass film having a low refractive index of added SiO ₂ is formed.

When taking out the substrate 25 on which the glass film has been formed from the reaction vessel 11, the inside of the reaction vessel 11 is broken to atmospheric pressure and then taken out from the substrate inlet / outlet 41. At this time, N ₂ gas is sprayed onto the substrate 25 from the gas shower 44 in the reaction chamber front chamber 42 to remove dust and the like adhering to the upper and lower surfaces of the substrate 25.

  From the above, since the open space 26 is formed on the lower electrode 16 and the substrate 25 is fixed substantially in parallel, and the glass film is manufactured on the upper surface and the lower surface of the substrate 25, the film formation time of the glass film can be shortened. Extremely efficient and economical.

  Furthermore, even if there is a large difference in the thermal expansion coefficient or softening temperature between the substrate 25 and the glass film, a glass film having substantially the same composition can be simultaneously formed not only on the substrate surface but also on the lower surface of the substrate. Almost no warpage occurs.

  The upper surface and the lower surface of the substrate 25 are sufficiently heated by the radiant heat from the lower electrode 16 and the upper electrode 18, and plasma is generated not only on the upper surface of the substrate 25 but also on the lower surface of the substrate 25. Since the gas which reacts to the substrate 25 can also flow into the lower surface of the substrate 25, a glass film having substantially the same composition can be formed not only on the upper surface of the substrate 25 but also on the lower surface of the substrate 25 at the same time.

  In this embodiment, since an alcoholate-based liquid source is vaporized, gas can be circulated into a slight gap, and not only on the substrate surface but also on the lower surface of the substrate 25. Glass films having the same composition can be formed simultaneously.

  Further, since the substrate is hardly warped, a plurality of glass films having different glass compositions can be easily formed on the upper surface and the lower surface of the substrate 25.

  In order to form the glass film by heating the upper electrode 18 and the lower electrode 16 to the same desired temperature, the glass films formed on the upper and lower surfaces of the substrate may be formed with substantially the same composition and substantially the same film thickness. it can.

  As long as the substrate 25 can withstand the heating temperature, any of glass materials such as quartz glass and multicomponent glass, semiconductor materials (Si, GaAs, InP, etc.), ceramics, polymer materials, and ferroelectric materials can be used. Good.

  By selecting a material for forming the substrate 25 in a wide range, it can be applied to a reflection mirror glass film, a filter glass film, a deflection mirror glass film, an insulating glass film, a light diffusion glass film, and the like.

As the glass raw material gas, an SiH ₄ -based gas may be used in addition to a gas obtained by vaporizing an alcoholate-based liquid source.

  Further, the high frequency power may be higher than 13.56 MHz, or may be a microwave frequency.

  The heating temperature of the upper electrode 18 and the lower electrode 16 should just be in the temperature range of 300 to 600 degreeC, and may be infrared heating other than resistance heating. This is because if the electrode temperature is lower than 300 ° C., it is difficult to obtain a uniform and low-loss glass film, and if it is higher than 600 ° C., it is difficult to provide a member or device for maintaining a vacuum.

Further, in addition to the Si-based liquid source 28, O ₂ gas, and C ₂ F ₆ gas, a Ge-based liquid source 31, a P-based liquid source 34, N ₂ gas, and NH ₃ gas are used so that the upper and lower surfaces of the substrate 25 are formed. SiO ₂ film, SiO ₂ film containing GeO _2, SiO ₂ film containing P ₂ O _5, may be further formed a glass layer which N is added.

  The mechanical booster pump 14 and the dry pump 15 that are the large-capacity exhaust devices 13 provided in the manufacturing apparatus 1 are not limited to two sets, and two or more sets may be provided.

However, the exhaust device needs to have a large displacement. This is because gases such as N ₂ , C ₂ F ₆ , and NH ₃ are used to add a large amount of N and F into the glass film of SiO ₂ , but there are few oxygen defects and little OH group contamination. In order to form a glass film, it is necessary to flow at least 100 sccm. When the flow rate of a gas such as N ₂ , NH ₃ , C ₂ F ₆ is increased, the flow rate of O ₂ needs to be increased accordingly.

  Therefore, in order to introduce a large flow of gas and keep the inside of the reaction vessel 11 at a high vacuum level, a large capacity exhaust device is required. Thereby, a glass film can be formed in a high vacuum while flowing a large amount of gas into the reaction vessel 11.

  Further, a substrate 25 in which at least one of both surfaces of the substrate 25 is polished in a mirror state may be used. By using a substrate polished in a mirror state, a glass film having a uniform distribution of film thickness, refractive index, and the like can be formed.

  Next, a method for manufacturing a waveguide will be described with reference to FIGS.

  First, as shown in FIG. 3A, a glass film serving as a lower clad layer having a low refractive index is formed on the upper and lower surfaces of the quartz glass substrate 50.

In a state where the upper electrode 18 and the lower electrode 16 shown in FIG. 1 are heated to 400 ° C., a gas obtained by vaporizing [Si (OC ₂ H ₅ ) ₄ ], an O ₂ gas, and a C ₂ F ₆ gas are used as a tape heater 45. In the gas supply pipe 23 heated to the desired temperature, the gas flow ratio O ₂ : C ₂ F ₆ is mixed and superposed so as to be 4: 1, and then introduced into the reaction vessel 11 for 35 minutes in the plasma atmosphere. First glass films 51 and 52 are formed as lower clads below.

  In this step, a glass film 51 having a refractive index of 1.438 ± 0.001 at a wavelength of 632.8 nm can be formed on the upper surface of the substrate 50 with a thickness of 2.1 μm ± 0.3 μm. A glass film 52 having a refractive index of 1.438 ± 0.0008 at .8 nm could be formed to a thickness of 2.0 μm ± 0.2 μm.

  In addition, a process of forming the first glass film by changing the film forming conditions of the first glass films 51 and 52 described above will be described.

The heating temperature of the upper electrode 18 and the lower electrode 16, the gas used and the deposition time are the same, O ₂ gas of C ₂ F ₆ gas flow ratio of _{O 2: C 2 F 6 =} 13: set to 1. Thus, a glass film having a refractive index of 1.415 ± 0.0014 at a wavelength of 632.8 nm can be formed on the upper surface of the substrate with a thickness of 2.0 μm ± 0.35 μm, and a refractive index at a wavelength of 632.8 nm can be formed on the lower surface of the substrate. A glass film of 1.414 ± 0.001 could be formed with a thickness of 1.9 μm ± 0.3 μm.

  Since the first glass films 51 and 52 are obtained by forming the first glass films 51 and 52 on the upper and lower surfaces of the quartz glass substrate 50 while being heated to approximately 400 ° C., the first glass films 51 and 52 are glass films that are stable with respect to temperature. Even if the glass film was heat-treated at a higher temperature in the range of 800 to 1200 ° C., the refractive index of the glass film remained almost unchanged and was a stable glass film.

  Next, as shown in FIG. 3B, a second glass film that forms a core layer on the upper surface of the substrate 50 is formed on the first glass films 51 and 52.

While the upper electrode 18 and the lower electrode 16 are heated to 400 ° C., the vaporized vapor, O ₂ gas, and N ₂ gas of [Si (OC ₂ H ₅ ) ₄ ] heated to 75 ° C. in a thermostat are taped The gas is introduced into the gas supply pipe 23 heated at 80 ° C. by the heater 45. The gas flow ratio was N ₂ : O ₂ = 10: 1 mixed and superimposed, and then introduced into the reaction vessel 11 to form second glass films 53 and 54 in a plasma atmosphere for 35 minutes.

  As a result, the second glass film 53 having a refractive index of 1.47012 ± 0.0006 at a wavelength of 632.8 nm is formed on the upper surface of the first glass film 51 on the upper surface of the substrate 50 with a thickness of 1.8 μm ± 0.46 μm. A second glass film 54 having a refractive index of 1.4698 ± 0.0014 at a wavelength of 632.8 nm is formed on the upper layer (lower side in the drawing) of the first glass film 52 on the lower surface of the substrate 50 by 1.8 μm ± 0. A thickness of 23 μm could be formed.

  In addition, a process of forming the second glass film by changing the film forming conditions of the second glass films 53 and 54 described above will be described.

With the upper electrode 18 and the lower electrode 16 heated to 400 ° C., the flow rate of [Si (OC ₂ H ₅ ) ₄ ] is set to 6 sccm, and the flow rate of [Ge (OCH ₃ ) ₄ ] is set to 0.8 sccm to keep the temperature constant. Steam vaporized by heating to 75 ° C. in the tank, and O ₂ gas and N ₂ gas are introduced into the supply pipe 23 heated to 80 ° C. by the tape heater 45. The gas flow ratio N ₂ : O ₂ was mixed at 14: 1 and superimposed, and then introduced into the reaction vessel 11 to form a second glass film in a plasma atmosphere for 35 minutes.

  As a result, a second glass film having a refractive index of 1.498 ± 0.0004 at a wavelength of 632.8 nm can be formed in a thickness of 1.98 μm ± 0.04 μm on the first glass film upper layer on the upper surface of the substrate. A second glass film having a refractive index of 1.497 ± 0.009 at a wavelength of 632.8 nm was formed on the upper layer of the first glass film on the lower surface with a thickness of 1.93 μm ± 0.10 μm.

  Next, as shown in FIG. 3C, the second glass film 53 is formed on the core layer 55 having a rectangular cross section.

  The second glass film 53 on the upper surface of the substrate 50 is heat-treated at 1000 ° C. for 2 hours in an oxygen atmosphere, then lowered to room temperature, and then a photoresist is applied onto the second glass film 53 and baked. A photomask on which the waveguide pattern of the core layer 55 is drawn is placed on the resist film, and ultraviolet rays are irradiated from above the photomask. After the ultraviolet irradiation, development is performed to obtain the same photoresist pattern as the waveguide pattern of the core layer 55 on the second glass film 53.

Next, using the photoresist pattern as an etching mask, the second glass film 53 is patterned while a CHF ₃ gas is allowed to flow as an etching gas in a dry etching process using a reactive ion etching apparatus (RIE). A core layer 55 having a shape is obtained.

  Next, as shown in FIG. 3D, the substrate having the core layer 55 is put into the apparatus 1 again, and the third glass films 56 and 57 having the same composition as the first glass films 51 and 52 are replaced with the cores. On the layer 55, the upper layer of the first glass film 51 and the upper layer of the second glass film 54 (lower side in the figure) were formed with a film thickness of about 10 μm.

  Thereafter, the substrate is heat-treated at 1100 ° C. in an oxygen atmosphere for 2 hours to complete the waveguide 58.

  What is necessary is just to give the high temperature heat processing within the range of 800 to 1350 degreeC.

  Next, the measurement results of the warpage and optical characteristics of the waveguide 58 manufactured by the above-described manufacturing method will be described.

  The warpage of the waveguide 58 occurs when the quartz glass substrate 50 having a diameter of 4 inches before the glass film is formed is about 7 μm, whereas the warp of the glass substrate after the formation of the waveguide 58 is about 9 μm. There is almost no warpage due to the waveguide formation. Therefore, glass films having the same composition and the same film thickness can be formed on the upper and lower surfaces of the substrate 50 under the same conditions.

  Propagation loss at a wavelength of 1550 nm in the TE mode and TM mode was measured in the waveguide 58 composed of a waveguide pattern composed of a straight line having a length of 30 cm and an S-shaped curve. As a result, there is almost no loss difference between TE and TM modes of 0.05 dB or less, and a waveguide with extremely small polarization dependence can be formed.

  Furthermore, by using the waveguide manufacturing method of the present embodiment, it has failed to obtain a waveguide core pattern processed into a rectangular shape by photolithography or dry etching as shown in FIG. In some cases, the waveguide pattern can be processed using the first and second glass films 52 and 54 laminated on the lower surface of the substrate 50. Thereby, the production yield of the waveguide can be improved and the cost of the waveguide can be reduced.

It is the schematic which shows the manufacturing apparatus of the glass film and waveguide of this Embodiment. The structure which fixes a board | substrate to the lower electrode of the manufacturing apparatus of FIG. 1 is shown, (a) is the upper top view, (b) is a side view. (A)-(d) is process sectional drawing which forms a glass film in both surfaces of a board | substrate, and forms a waveguide. It is the schematic which shows the manufacturing apparatus of the glass film by the conventional CVD method.

Explanation of symbols

11 Reaction vessel 16 Lower electrode 17 Gap 18 Upper electrode 24 Substrate fixing member 25 Substrate 26 Open space

Claims (14)

  The upper electrode and the lower electrode are arranged so as to face each other in the reaction vessel, a high voltage is applied to the electrode, the electrode is heated, and a gas serving as a glass raw material is introduced into the vessel to form a substrate in a plasma atmosphere. In a glass film manufacturing method for forming a glass thin film on a substrate, a substrate is disposed on the lower electrode through a gap, an open space is formed on the lower surface of the substrate, and a glass film is formed on the upper and lower surfaces of the substrate. A method for producing a glass film.   The method for producing a glass film according to claim 1, wherein the height of the gap is in the range of 2 mm to 15 mm.   The method for producing a glass film according to claim 1, wherein a substrate fixing member is provided on the lower electrode so as to be positioned on the outer periphery of the substrate disposed thereon.   4. The substrate fixing member is formed in a columnar shape, and at least three are provided on the outer periphery of the substrate, and the substrate is placed on the columnar substrate fixing member to form a film. Of manufacturing a glass film. 5. The method for producing a glass film according to claim 1, wherein the source gas is a gas obtained by vaporizing an alcoholate-based liquid source or a SiH ₄ -based gas.   The method for producing a glass film according to claim 1, wherein a plurality of glass films having different glass compositions are laminated on both surfaces of the substrate.   The method for producing a glass film according to claim 1, wherein the substrate is a substrate formed of glass, semiconductor, ceramics, and a polymer material.   The manufacturing method of the glass film in any one of Claim 1 to 7 using the board | substrate with which at least one of both surfaces of the said board | substrate was grind | polished in the mirror surface state.   The manufacturing method of the glass film in any one of Claim 1 to 8 which heated the said upper electrode and the lower electrode to the same temperature within the range of 300-600 degreeC. A gas obtained by vaporizing Si (OC ₂ H ₅ ) ₄ into the source gas and a gas mixed with O ₂ gas and C ₂ F ₆ gas are introduced at a predetermined mixing ratio to form a glass film to which fluorine is added. The method for producing a glass film according to claim 1.   A method for producing a glass film, comprising: laminating a glass layer having a refractive index higher than that of the glass film on an upper layer of the glass film produced by the production method according to claim 10. A step of subjecting the glass film formed by the method for producing a glass film according to any one of claims 1 to 11 to a high temperature heat treatment at a temperature within a range of 800 ° C to 1350 ° C;
And a step of forming a waveguide pattern by photolithography and dry etching. A gas obtained by vaporizing Si (OC ₂ H ₅ ) ₄ , an O ₂ gas, and C ₂ F ₆ on the waveguide pattern on the upper surface of the substrate and the glass film on the lower surface of the substrate formed by the waveguide manufacturing method according to claim 12. A method of manufacturing a waveguide, wherein a mixed gas is introduced at a predetermined mixing ratio to form a glass film to which fluorine is added. 14. A method for manufacturing a waveguide, comprising subjecting a substrate on which a waveguide pattern formed by the method for manufacturing a waveguide according to claim 13 is formed to a high temperature heat treatment within a temperature range of 800.degree. C. to 1350.degree.

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