WO2003012497A1

WO2003012497A1 - Quartz-plane light circuit element and process for producing the same

Info

Publication number: WO2003012497A1
Application number: PCT/JP2001/006600
Authority: WO
Inventors: Fumio Matsumura
Original assignee: Asahi Optronics, Ltd.; Sun Instruments, Inc.
Priority date: 2001-07-31
Filing date: 2001-07-31
Publication date: 2003-02-13

Abstract

A quartz-plane light circuit element which comprises: a monocrystalline silicon substrate or synthetic quartz glass substrate (11); a lower cladding film (13) consisting mainly of silicon dioxide and formed by vapor deposition on one side of the substrate (11); a core part (17) of a given shape consisting mainly of silicon dioxide and formed by vapor deposition on a part of the lower cladding film (13); an upper cladding film (15) which has been deposited by vapor deposition so as to cover the core part (17) and the lower cladding film (13) and which consists mainly of silicon dioxide or comprises silicon dioxide and evenly incorporated therein either phosphorus pentaoxide or phosphorus pentaoxide and boron trioxide; and a distortion-correcting film (19) consisting mainly of silicon dioxide and formed by vapor deposition on the other side of the substrate (11).

Description

Description Quartz planar optical circuit element and manufacturing method thereof

The present invention relates to a quartz planar optical circuit element necessary for realizing an arrayed optical waveguide grating element and the like indispensable for wavelength division multiplexing optical communication, and a method of manufacturing the quartz planar optical circuit element. Background art

Conventionally, for example, a flame deposition method is known as a method for manufacturing a quartz planar optical circuit element.

As shown in Fig. 3, this flame deposition method is a method in which a plurality of substrates 33 are arranged side by side around a disk 31 rotating in the direction of arrow A, and glass fine powder containing silicon dioxide as a main component. after a 3 5 deposited on the substrate 3 3, by using oxygen (0 ₂₎ and hydrogen (H ₂₎ and bar Na 3 7 issuing oxyhydrogen flame 3 9 for combusting a mixture of, This is a method in which glass fine powder 35 is melted and vitrified at a high temperature of 1000 ° C. or higher.

FIG. 4 is a diagram showing a cross-sectional structure of a conventional quartz planar optical circuit element manufactured using such a flame deposition method. In manufacturing the quartz planar optical circuit device shown in FIG. 4, first, one surface of a silicon single crystal substrate (or a synthetic quartz glass substrate) 41 (in this case, the upper surface of the diagram) and five portions of silicon dioxide A lower cladding film 43 is formed by depositing a powder containing phosphorus oxide and boron trioxide and melting and vitrifying the powder at a high temperature of 1000 ° C. or more.

Next, on the upper surface of the lower cladding film 43, silicon dioxide and lithium pentoxide were added. A core film is formed by depositing a powder obtained by adding germanium dioxide further to boron and boron trioxide and melting and vitrifying at a high temperature of −100 ° C. or higher, and then a predetermined position on the upper portion of the core film Next, a rectangular etching mask is formed using photolithography technology, and the core film is formed into a rectangular shape using reactive ion etching (RIE) to form a core portion 47. Further, a powder obtained by adding phosphorus pentoxide and boron trioxide to silicon dioxide is deposited so as to cover the lower cladding film 43 and the core portion 47, and melted at a high temperature of 100 ° C. or more. The upper clad part 45 is formed by vitrification.

However, in the conventional quartz planar optical circuit device manufactured using the above-mentioned flame deposition method, powder is first deposited by intermittent film formation on a base slope and then vitrified by heat treatment. There has been a problem that it is difficult to obtain a film having a uniform refractive index even in the film mouth.

At the same time, after laminating a powder containing silicon dioxide as a main component on the substrate, it is vitrified at a high temperature of 1000 ° C. or more in an electric furnace or the like. The possibility that a large residual stress is generated increases. This is, for example, the “Quartz-based flare optical circuit” of the 7th Lightwave Sensing Technology Study Group of the Japan Society of Applied Physics, LST 7- 16, pp. 1 2 1-1 2 6 (1991 1, 5, 2 3) and so on. For this reason, there is a problem that the dependence of the optical waveguide on the polarization loss is increased, and the warpage of the substrate is also increased, thereby deteriorating the connectivity with the optical fiber. This point will be described in more detail. For example, when a radius of curvature of a warp caused by a distortion of a film stress when a uniform film having a thickness t 2 is formed on a substrate having a thickness t 1 is represented by r, this r is expressed by the following equation (1) ) (See Technical Report of IEICE, OPE95-55, PP49-54 (1995-08)). r = {1 / (a) a 2) d T} {(tl + t 2) / 2 + l / [6 X (t 1 + t 2)] X (] tl-S l + l / t 2- S 2) X (S 1 / t 1 3 + S 2 / t 2 3)} (1)

In the above equation (1), tn is the thickness of each layer (hereinafter, n is an arbitrary integer), an is the coefficient of thermal expansion of each layer material, d T is the temperature difference between stress-free temperature and normal temperature, and Sn is Sn = In the relationship of EnZ (1-vn), En is the Young's modulus of each layer material, and Vn is the Poisson's ratio of each layer material.

According to this equation (1), the larger the radius of curvature r, the smaller the internal stress of each layer. That is, the smaller the (al_a2) and dT, the smaller the internal stress.

However, if the value of the radius of curvature r becomes negative, a tensile stress is generated in the film and the film is easily brittle, and therefore the value of r is preferably positive. Thermal expansion coefficient of the general silicon single crystal substrate, it is said that approximately 5 X 1 0- ^6. The thermal expansion coefficient of the silicon dioxide film of amorphous, approximately equal to the synthetic quartz glass board, the thermal expansion coefficient of the silicon dioxide film as crystals from 7 X 1 0- ⁶ in 1 4 X 1 0-6 about is there.

As described above, when a quartz planar optical circuit element is manufactured by the conventionally used flame deposition method, the polarization dependence of the waveguide loss of the optical waveguide and the warpage of the substrate increase, and the connectivity with the optical fiber deteriorates. Therefore, it was extremely difficult to mass-produce high-performance planar optical circuit elements.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems of the conventional example, and provides a quartz planar optical circuit element which is less dependent on the polarization of waveguide loss, has no substrate warpage, and is excellent in mass production. The purpose is to provide. Disclosure of the invention

In order to solve the above-mentioned problems and achieve the object, the quartz planar light of the present invention is used. The circuit element includes a lower cladding film (13) containing silicon dioxide as a main component formed by vapor deposition on one surface of a silicon single crystal substrate or a synthetic quartz glass substrate (11), and the lower cladding film. (13) A core part (17) of a predetermined shape formed by vapor deposition of a material mainly composed of silicon dioxide on a part of the upper part, and the core part (17) and the lower cladding film (13) ), Or an upper cladding film formed by vapor deposition by adding phosphorus pentoxide or phosphorus pentoxide and boron trioxide uniformly to silicon dioxide. And a membrane (15).

The quartz planar optical circuit device according to the present invention further includes a strain correction film (19) containing silicon dioxide as a main component formed by vapor deposition on the surface opposite to the substrate (11).

Further, in the quartz planar optical circuit device according to the present invention, the distortion correction film (19) has substantially the same thermal expansion coefficient as the material of the lower cladding film (13) and the upper cladding film (15). It consists of the material which has.

Further, in the quartz planar optical circuit device according to the present invention, the material mainly composed of silicon dioxide for forming the core portion (17) is a material obtained by adding germanium dioxide to silicon dioxide. The quartz planar optical circuit device according to claim 1.

In addition, the method for manufacturing a quartz planar optical circuit element of the present invention is characterized in that the lower clad film mainly composed of silicon dioxide is formed on one surface of a silicon single crystal substrate or a synthetic quartz glass substrate (11) by vapor deposition. Forming a core film mainly composed of silicon dioxide on the lower cladding film (13) by vapor deposition; and processing the core film into a predetermined shape by anisotropic etching. Forming a core portion (17) by heating, and an upper cladding film mainly composed of silicon dioxide so as to cover the core portion (17) and the lower cladding film (13). (15) or pentoxide or pentoxide on silicon dioxide A step of forming an upper clad film (15) to which phosphorous chloride and boron trioxide are uniformly added by vapor deposition, and a step of melting the upper clad film (15) by heat treatment.

In the method for manufacturing a quartz planar optical circuit device according to the present invention, the step of forming a distortion correction film (19) containing silicon dioxide as a main component on the surface on the opposite side of the substrate (11) by vapor deposition is included. In addition.

In the method of manufacturing a quartz planar optical circuit device according to the present invention, the distortion correction film (19) is substantially the same as the material of the lower cladding film (13) and the upper cladding film (15). It is made of a material having a coefficient of thermal expansion.

In the method for manufacturing a planar quartz optical circuit device according to the present invention, the material containing silicon dioxide as a main component for forming the core film is a material obtained by adding germanium dioxide to silicon dioxide. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional configuration diagram of a quartz planar optical circuit device according to one embodiment of the present invention.

FIG. 2A is a diagram showing a step of manufacturing the quartz planar optical circuit device of FIG. FIG. 2B is a diagram showing a step of manufacturing the quartz planar optical circuit device of FIG. FIG. 2C is a diagram showing a step of manufacturing the quartz planar optical circuit device of FIG. FIG. 2D is a diagram showing a step of manufacturing the quartz planar optical circuit device of FIG. FIG. 2E is a diagram showing a step of manufacturing the quartz planar optical circuit element in FIG. 1. FIG. 2F is a diagram showing a step of manufacturing the quartz planar optical circuit device in FIG. 1. FIG. 2G is a diagram showing a step of manufacturing the quartz planar optical circuit device in FIG. FIG. 2H is a diagram showing a step of manufacturing the quartz planar optical circuit device of FIG. FIG. 3 is a view for explaining a film deposition method by a flame deposition method.

Fig. 4 shows a conventional quartz planar optical circuit element manufactured using the flame deposition method. It is sectional drawing. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a preferred embodiment of the present invention will be described.

The quartz planar optical circuit element of the present embodiment includes a lower clad film mainly composed of silicon dioxide formed by vapor deposition on one surface of a silicon single crystal substrate or a synthetic quartz glass substrate, and the lower clad film. Germanium dioxide or the like is uniformly added to silicon dioxide on the upper part of the silicon dioxide, and silicon dioxide is formed so as to cover a core having a predetermined shape formed by vapor deposition and the core and the lower cladding film. Phosphorus pentoxide or phosphorous pentoxide and boron trioxide are uniformly added to an upper cladding film or a silicon dioxide, and the upper cladding film formed by vapor deposition and vapor deposition on the surface opposite to the substrate And a distortion correction film containing silicon dioxide as a main component and formed by the above method.

In this embodiment, the deposition material is directly ionized and adhered to the substrate by electric field acceleration (ion plating deposition method), or the ionized gas is accelerated by an electric field to collide with the deposition material and adhere the deposition material to the substrate. Using a lower cladding film composed mainly of silicon dioxide on the substrate, and a core portion made of silicon dioxide uniformly doped with germanium dioxide, etc. An upper cladding film mainly composed of silicon dioxide or an upper cladding film obtained by uniformly adding phosphorus pentoxide or phosphorus pentoxide and boron trioxide to silicon dioxide is disposed on the upper cladding film. Is to provide a distortion correction film mainly composed of silicon dioxide. By doing so, each film is formed at a relatively low temperature, so that the residual stress (film formation stress) of each film is reduced, the refractive index distribution of the optical waveguide is uniform, and the waveguide is formed by the film formation stress. It is possible to obtain a flat-surface circuit element having almost no polarization dependence of loss. In addition, the carbon dioxide Since the coefficient of thermal expansion of the film containing silicon as the main component and the coefficient of thermal expansion of the strain correction film containing silicon dioxide as the main component on the back side of the substrate are substantially the same, the residual strain on the front side and the back side of the substrate cancel each other. Work on. For this reason, it is possible to obtain a quartz planar circuit device which hardly warps the substrate, has excellent connectivity with the optical fiber, and can obtain high mass productivity.

The method for manufacturing a quartz planar optical circuit element according to the present embodiment includes a step of forming a lower clad film mainly composed of silicon dioxide on one surface of a silicon single crystal substrate or a synthetic quartz glass substrate by vapor deposition; Forming a core film on a clad film by uniformly depositing silicon dioxide with germanium dioxide or the like by vapor deposition; forming the core film by processing the core film into a predetermined shape by anisotropic etching; An upper cladding film composed mainly of silicon dioxide or an upper cladding obtained by uniformly adding phosphorus pentoxide or phosphorus pentoxide and boron trioxide to silicon dioxide so as to cover the core portion and the lower cladding film. Forming the upper clad film by heat treatment; and forming silicon dioxide as a main component on the surface on the opposite side of the substrate. And forming by vapor deposition a correction film.

In this method, a lower cladding film containing silicon dioxide as a main component is formed on the front side of a substrate by using an ionization vapor deposition method such as an ion plating vapor deposition method or an ion beam assisted vapor deposition method. A core film to which germanium or the like is uniformly added is formed, the core film is processed into a predetermined shape by anisotropic etching, a core portion is formed, and a carbon dioxide is formed so as to cover the core portion and the lower cladding film. An upper cladding film composed mainly of silicon or an upper cladding film in which phosphorus pentoxide or phosphorus pentoxide and boron trioxide are uniformly added to silicon dioxide is formed, and the upper cladding film is melted by heat treatment. In addition, a strain correction film containing silicon dioxide as a main component is formed on the opposite surface of the substrate. By doing so, each film can be compared Since the film is formed at a low temperature, the residual stress (film formation stress) of each film is small, the refractive index distribution of the optical waveguide is uniform, and the polarization dependence of the waveguide loss due to the film formation stress is almost flat. A circuit element can be obtained. Also, since the film mainly composed of silicon dioxide on the front side of the substrate and the distortion correction film mainly composed of silicon dioxide on the rear side of the substrate have substantially the same coefficient of thermal expansion, the front side and the rear side of the substrate The residual strains on the sides act to cancel each other. For this reason, it is possible to obtain a quartz planar circuit element that hardly warps the substrate, has excellent connectivity with an optical fiber, and can obtain high mass productivity.

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

FIG. 1 is a cross-sectional view showing one configuration example of a quartz planar optical circuit element according to the present embodiment.

First, as shown in FIG. 1, the quartz planar optical circuit element of the present embodiment is formed on one surface (the upper surface in the figure) of a substrate 11 such as a silicon single crystal substrate or a synthetic quartz glass substrate by ionization vapor deposition ( Using ion plating deposition or ion beam deposition, a lower clad film 13 is formed by adding silicon dioxide alone or germanium dioxide or titanium dioxide to silicon dioxide uniformly, and the lower clad film 13 is formed. An upper cladding film mainly composed of silicon dioxide or a rectangular core portion 17 made of silicon dioxide uniformly doped with germanium dioxide or the like is formed on the cladding film 13 by ionization vapor deposition. Using ionization deposition on parts 17 and the lower cladding film 13, apply phosphorus pentoxide to silicon dioxide or phosphorus pentoxide and boron trioxide to silicon dioxide uniformly. An upper clad film 15 is formed, and the surface opposite to the substrate 11 (the lower surface in the figure) is a distortion correction film that performs distortion correction by adding silicon dioxide alone or titanium dioxide to silicon dioxide uniformly. It is composed by arranging nineteen. Next, an example of a method for manufacturing the quartz planar optical circuit element will be described.

2A to 2H are diagrams showing the steps of manufacturing the quartz planar optical circuit device shown in FIG.

In this embodiment, as shown in FIG. 2A, one surface (upper surface) of a substrate 11 such as a silicon single crystal substrate or a synthetic quartz glass substrate is formed by ionization vapor deposition (ion plating vapor deposition). Or an ion beam assisted vapor deposition method) to form a lower clad film 13 alone of silicon dioxide or by uniformly adding germanium dioxide or titanium dioxide to silicon dioxide.

Next, as shown in FIG. 2B, a core film 17 ′ having a higher refractive index obtained by uniformly adding germanium dioxide or the like to silicon dioxide was used to form a lower cladding film 13, as shown in FIG. 2B. Form on top.

Then, as shown in FIG. 2C, a metal mask 21 is formed on the formed core film 17 ′ using a sputtering method, and a photoresist 23 is applied thereon. An optical waveguide pattern is formed on the photo resist by an exposure device in which a photo mask is set by using a trisography technique, and a patterned photo resist 23 is formed (see FIG. 2D). Next, as shown in FIG. 2E, the metal mask 21 is patterned by reactive ion etching (RIE) using the pattern of the photoresist 23 as a mask, and the core film is further formed using the metal mask 21. 17 'is processed into a rectangular shape by reactive ion etching (RIE) to form a core 17 (see Fig. 2F).

Next, as shown in FIG. 2G, after the metal mask 21 was removed using reactive ion etching, the core 17 and the lower cladding film 13 were covered by ionization vapor deposition. An upper clad film 15 is formed by uniformly adding phosphorus pentoxide and boron trioxide to silicon dioxide. Perform heat treatment for 0 minutes to melt and flatten the surface. The upper cladding film mainly composed of silicon dioxide may be used as it is without heat treatment.

Finally, as shown in FIG. 2H, on the opposite side (lower surface) of the substrate 11, a silicon dioxide alone or a silicon dioxide or titanium dioxide or the like is added uniformly to provide a distortion correction film 19 9 for performing the distortion correction. Is formed by an ionization vapor deposition method. As the material of the distortion compensation film 19, it is desirable to use a material having a thermal expansion coefficient substantially equal to that of the material of the lower cladding film 13 and the material of the upper cladding film 15.

In the single-mode optical waveguide manufactured in this manner, the lower cladding film 13 and the upper cladding film 15 generally have a thickness of 10 to 30 μm, and the core portion 17 has a thickness of 6 to 30 μm. The relative refractive index difference between the core and the cladding is 0.25 to: about 1.5%.

As described above, according to the present embodiment, when forming each film constituting the quartz planar optical circuit element, the ionization vapor deposition method is used instead of the conventional flame deposition method. Film formation can be performed uniformly and continuously from a point evaporation source, and the film thickness can be made uniform, and a light guide having a uniform refractive index distribution between film formation ports and within the film formation port. Wave path can be realized.

In addition, the ionization deposition method used in this embodiment has a lower cladding film, a core film, and an upper cladding film at a low temperature of about 200 ° C., compared with the flame deposition method of about 100 ° C. Since the waveguide film can be formed, the film formation stress (residual stress) generated in the optical waveguide is reduced, and the polarization loss of the waveguide loss can be reduced.

Further, according to the present embodiment, since the distortion correction film 19 having substantially the same thermal expansion coefficient as the film on the front surface side is formed on the back surface side of the substrate, it is possible to correct the warpage of the substrate, and thus more complete. Optical polarization It is possible to provide a quartz planar optical circuit element having excellent connectivity with a bus and high productivity.

The operation of the present embodiment described above is summarized as follows.

(1) When the lower cladding film 13 is formed on the surface of the substrate 11 as shown in FIG. 2 (a), for example, the thermal expansion coefficient of the material of the substrate 11 and the lower cladding film

If the materials 13 have different coefficients of thermal expansion, the higher the temperature at which the lower cladding film 13 is formed, the greater the difference between the thermal expansion of the substrate 11 and the thermal expansion of the lower cladding 13. Becomes larger. That is, if the substrate 11 and the lower cladding film 13 are cooled to room temperature, the substrate 11 and the lower cladding film 13 shrink and the substrate 11 The dimension and the dimension of the lower cladding film 13 have a dimensional difference proportional to the difference between the deposition temperature and the room temperature. This causes residual stress (deposition stress) on the substrate 11 and the lower cladding film 13. ) And residual strain. This causes the polarization dependence of the waveguide loss and the warpage of the substrate.

In this regard, in the present embodiment, the substrate 11 and the lower cladding film are used because the ionization deposition method capable of processing at about 200 ° C. is used instead of the flame deposition method of about 100 ° C. Even when the materials 13 have different coefficients of thermal expansion, the residual stress and residual strain generated in the substrate 11 and the lower cladding film 13 can be reduced. Therefore, according to this embodiment, the polarization dependence of the waveguide loss and the warpage of the substrate can be reduced.

(2) Further, as shown in FIG. 2 (h), a distortion correction film 19 made of a material having substantially the same thermal expansion coefficient as the material of the lower cladding film 13 is formed on the back surface of the substrate 11. When the film is formed, in the process of forming the distortion correction film 19, residual strain opposite to the residual strain generated in the process of forming the lower cladding film 13 is generated. Warpage can be further reduced.

As described above, according to the above embodiment, the ion plating The lower cladding film composed mainly of silicon dioxide, the core, the upper cladding film, and the other side of the substrate are formed on one surface of the substrate by ionization vapor deposition such as ion vapor deposition or ion beam assisted vapor deposition. Since the strain correction film is formed on the surface of the optical waveguide, the refractive index distribution of the optical waveguide becomes uniform, and the polarization dependence of the waveguide loss due to the film formation stress (residual stress) and the warpage of the substrate are almost eliminated. Therefore, it has excellent connectivity with optical fibers and high mass productivity can be obtained.

Also, a lower cladding film is formed on one side of the substrate using an ionization vapor deposition method such as ion plating vapor deposition or ion beam assisted vapor deposition, and a core film is formed thereon. Is processed into a predetermined shape by anisotropic etching to form a core portion, an upper cladding film is formed so as to cover the core portion and the lower cladding film, and the upper cladding film is directly or heat-treated. The optical waveguide is made uniform, and the refractive index distribution of the optical waveguide becomes uniform, resulting in polarization dependence of waveguide loss due to film formation stress and substrate warpage. Is almost eliminated, excellent connectivity with optical fiber, and high mass productivity.

The present invention can be applied to a modification or modification of the above embodiment without departing from the gist of the invention. Industrial applicability

As described above, according to the present invention, the lower cladding film (1) composed mainly of silicon dioxide formed on one surface of a silicon single crystal substrate or a synthetic quartz glass substrate (11) by vapor deposition. 3), a core part (17) having a predetermined shape in which a material mainly composed of silicon dioxide is formed on a part of the lower clad film (13) by vapor deposition, and the core part (17). Phosphorus pentoxide or phosphorus pentoxide and trioxide are added to the upper cladding film (15) or silicon dioxide mainly containing silicon dioxide so as to cover the lower cladding film (13). Since the quartz planar optical circuit element was configured to include boron and an upper cladding film (15) formed by vapor deposition, the refractive index distribution of the optical waveguide became uniform, and film deposition stress (residual The polarization dependence of the waveguide loss due to stress) and the warpage of the substrate are almost eliminated, and the connection with the optical fiber is excellent and high productivity can be obtained.

In addition, since a distortion correction film (19) containing silicon dioxide as a main component formed by vapor deposition is further provided on the surface on the opposite side of the substrate (11), the residual distortion of the planar optical circuit element can be reduced. It is possible to suppress the warpage of the substrate.

Also, since the distortion correction film (19) is made of a material having substantially the same coefficient of thermal expansion as the material of the lower cladding film (13) and the upper cladding film (15), The warpage of the substrate can be effectively prevented.

Forming a lower cladding film (13) containing silicon dioxide as a main component by vapor deposition on one surface of a silicon single crystal substrate or a synthetic quartz glass substrate (11); 13) a step of forming a core film containing silicon dioxide as a main component thereon by vapor deposition, a step of forming the core portion (17) by processing the core film into a predetermined shape by anisotropic etching, In order to cover the core portion (17) and the lower cladding film (13), the upper cladding film (15) containing silicon dioxide as a main component or the silicon dioxide on phosphorus pentoxide or phosphorus pentoxide and trioxide. A step of forming an upper clad film (15) to which boron oxide is uniformly added by vapor deposition, and a step of melting the upper clad film (15) by heat treatment so as to include: Since the manufacturing method of The refractive index distribution of the optical waveguide becomes uniform, warpage of the polarization dependence and the substrate of the waveguide loss due to deposition stress almost eliminated, excellent connectivity with the optical fiber, high productivity is obtained.

Claims

The scope of the claims

1. A lower cladding film (13) mainly composed of silicon dioxide formed on one side of a silicon single crystal substrate or a synthetic quartz glass substrate (11) by vapor deposition;

A core part (17) having a predetermined shape formed by vapor deposition of a material containing silicon dioxide as a main component on a part of the lower cladding film (13);

In order to cover the core part (17) and the lower cladding film (13), phosphorus pentoxide or phosphorus pentoxide is added to the upper cladding film (15) or silicon dioxide containing silicon dioxide as a main component. An upper clad film (15) formed by uniform addition of boron trioxide and evaporation,

A quartz planar optical circuit device comprising:

2. The quartz planar optical circuit according to claim 1, further comprising a distortion correction film (19) containing silicon dioxide as a main component formed by vapor deposition on the surface on the opposite side of the substrate (11). element.

3. The distortion correction film (19) is made of a material having substantially the same coefficient of thermal expansion as the material of the lower cladding film (13) and the upper cladding film (15). Item 3. The quartz planar optical circuit element according to Item 2.

4. The planar quartz optical circuit according to claim 1, wherein the material containing silicon dioxide as a main component forming the core portion (17) is a material obtained by adding germanium dioxide to silicon dioxide. element.

5. a step of forming a lower cladding film (13) containing silicon dioxide as a main component on one surface of a silicon single crystal substrate or a synthetic quartz glass substrate (11) by vapor deposition;

Forming a core film composed mainly of silicon dioxide on the lower cladding film (13) by vapor deposition; Processing the core film into a predetermined shape by anisotropic etching to form a core portion (17);

In order to cover the core part (17) and the lower cladding film (13), phosphorus pentoxide or phosphorus pentoxide is added to the upper cladding film (15) or silicon dioxide containing silicon dioxide as a main component. Forming an upper clad film (15) to which boron trioxide is uniformly added by vapor deposition;

Melting the upper cladding film (15) by heat treatment.

6. The quartz according to claim 5, further comprising a step of forming a strain correction film (19) containing silicon dioxide as a main component by vapor deposition on the surface on the opposite side of the substrate (11). A method for manufacturing a planar optical circuit element.

7. The strain correction film (19) is made of a material having substantially the same coefficient of thermal expansion as the material of the lower cladding film (13) and the upper cladding film (15). 7. The method for manufacturing a quartz planar optical circuit device according to claim 6.

8. The quartz planar optical circuit device according to claim 5, wherein the material containing silicon dioxide as a main component forming the core film is a material obtained by adding germanium dioxide to silicon dioxide. Production method.