WO1995025973A1

WO1995025973A1 - Method of production of reflecting waveguide device

Info

Publication number: WO1995025973A1
Application number: PCT/JP1995/000472
Authority: WO
Inventors: Akira Mugino; Yoshiyuki Kamata; Hisaharu Yanagawa
Original assignee: The Furukawa Electric Co., Ltd.
Priority date: 1994-03-22
Filing date: 1995-03-17
Publication date: 1995-09-28
Also published as: JPH07261043A; CA2163448A1

Abstract

A reflecting waveguide device which comprises a bent waveguide and a reflecting portion formed at the bent portion. The waveguide device is produced by forming a resist mask having a combined planar pattern, in which a planar pattern of the bent waveguide and another planar pattern similar to and greater area than the planar pattern at the reflecting portion partially overlap each other at the bent portion of the planar pattern of the bent waveguide, on a device substrate; and then carrying out dry etching so as to form a ridge portion having the same planar pattern as that of the combined planar pattern, and the step of forming a resist mask having the same planar pattern as that of the reflecting portion on the device substrate and then carrying out dry etching to form a recess having the same planar pattern as that of the reflecting portion on the device substrate.

Description

Specification

Method for manufacturing reflective waveguide device

Technical field

The present invention relates to a method of manufacturing a reflective waveguide device having a bent waveguide on a predetermined device substrate and a reflective portion at the bent portion by applying a photolithography technology and a dry etching technology. The present invention relates to a method of manufacturing a reflective waveguide element which can realize low reflection loss regardless of the order of the step of forming the bent waveguide and the step of forming the reflection section, and which has a high degree of freedom in the manufacturing process.

Background technology

In a reflective waveguide device, for example, an element substrate formed by laminating thin layers made of a dielectric or a compound semiconductor has an angle α.

(However, α is 0 ° <α <180 °) The bend waveguide that bends at 0 ° <α <180 ° and a part of the corner of the bend of the bend waveguide are cut off, and the cut surface is used as a reflective surface. And a reflecting portion which is formed.

The following method is known as a method for manufacturing such a reflective waveguide device.

For example, Trevor M. Benson, in J. of Lighttween Technology, Vol. LT-2, No. 1, Feb., 1984, first used an etching technique on the element substrate. A concave portion having a triangular flat surface pattern is formed as a reflecting portion so that one of the wall surfaces becomes a reflecting surface. A method is proposed in which the waveguide is bent with a flat pattern such that the reflecting surface of the shape crosses the bent portion obliquely. In addition, Japanese Patent Application Laid-Open No. 4-75008 and Y. Chung et al. Describe IE EE Photonics Technology Letters, Vol.

A paper published in Sep., 1992 discloses a method in which a reflective portion is first formed on an element substrate by applying dry etching technology, and then a bent waveguide is formed.

Further, E. Gini et al. Published a paper in Power Electronics Letters Vol. 28, No. 5, Feb., 1992, and H. Appelman et al., Ka of Lightwave Technology, Vol. 8, No. 1, Jan. A paper published in, discloses a method in which a bent waveguide is first formed on an element substrate by applying a dry etching technique, and then a reflecting portion is formed.

Here, a general manufacturing method of a reflection type waveguide device will be described with reference to the drawings. · First, on a substrate 1 a composed of n-type GaAs, a buffer layer 1 b composed of n-type GaAs and a lower cladding layer lc composed of n-type GaAs. The core layer 1 d composed of n-type GaAs, the upper cladding layer 1 e composed of n-type Al GaAs, and the cap layer 1 f composed of n-type GaAs are, for example, Mもの The elements stacked in this order by a film forming method such as the CVD method are prepared as the element substrate 1 (Fig. 1). The material constituting the element substrate 1 is, for example, In P / G a I n in addition to the above-mentioned G a As / A 1 G a As system. Asp-based compound semiconductors and the like are sometimes used. Further, a dielectric material such as quartz or LiNbOs formed on the Si substrate by a flame deposition method may be used. Then, as shown in FIG. 2, by applying a photolithography technique on the cap layer 1f, the plane pattern of the resist mask 2a having the same plane pattern as the bent waveguide to be formed is formed. To form In FIG. 2, the planar pattern of the resist mask 2a is a bent portion whose corner is bent at a right angle.

Then, applying dry etching technology, which irradiates a reactive ion beam or reactive ions from above the element substrate shown in Fig. 2, the part excluding the part covered with the resist mask 2a is removed. A part of the cladding layer 1e is partially removed by etching to a predetermined depth, and thereafter, the resist mask 2a is removed by a remover or oxygen plasma.

As a result, as shown in FIG. 3, on the remaining upper cladding layer le, there are two straight waveguides 3A and 3B, and a bent portion 3a bent at a right angle is formed. A bent waveguide 3 having a shape of a bridge is formed.

Next, as shown in FIG. 4, a resist mask 2b is formed on the exposed surface of the upper cladding layer 1e and the bent waveguide 3 by applying photolithography technology. I do. At this time, the resist mask 2b has a triangular planar pattern, and its side 4a has a bent waveguide. A window 4 is formed so as to obliquely cross the corner 3b of the bent portion 3a of the road 3 at an angle of 45 °. Therefore, from the window 4, the corner 3b in the bent portion 3a and a part of the surface of the upper cladding layer 1e are exposed.

Then, by applying a dry etching technique such as REBE (Reactive Ion Beam Etching) or RIE (Reactive Ion Etching) on the upper surface of the element substrate, the portion exposed from the window 4 is exposed to the buffer layer 1b or the substrate 1a. Etching is removed until the surface is exposed, and then the resist mask 2b is removed.

As a result, as shown in FIG. 5, the depth reaches the exposed surface of the buffer layer 1b or the substrate 1a, and a recess 5 having the same triangular shape as the window 4 is formed in the plane pattern. 'In this process, the corner 3b of the bent portion 3a of the bent waveguide 3 is cut off, and the cut surface 5a is exposed there. The cut surface 5a cuts the optical path axes of the two linear waveguides 3A and 3B constituting the bent waveguide 3 at an angle of 45 ° larger than the critical angle of the propagating light. Therefore, for example, the light propagating through the linear waveguide 3A is reflected by the cut surface 5a to change the optical path, and propagates through the linear waveguide 3B.

<o

That is, the cut surface 5a becomes a reflection surface, and the concave portion 5 having this reflection surface bends and functions as a reflection portion for the waveguide, and the reflection type waveguide element is obtained here. Can be

In addition, by coating each cut surface of the concave portion 5 with a metal thin film made of, for example, gold, silver, copper, aluminum, or the like, the function of the cut surface 5a as a reflection surface is more reliably achieved. In some cases, it can be demonstrated.

In the method of manufacturing the reflection type waveguide device shown in FIGS. 1 to 5, first, a bent waveguide is formed on the device substrate, and then a concave portion (reflection portion) 5 is formed. Conversely, a concave portion (reflection portion) 5 is first formed on the element substrate, and then a bent waveguide is formed.

By the way, the optical characteristics of a reflective waveguide device as shown in FIG. 5 are mainly determined by the following factors.

First, the first factor relates to the positional accuracy when the resist mask 2b shown in FIG. 4 is formed by applying one photolithography technique.

In other words, the resist mask 2b is formed so that one side 4a of the window 4 in FIG. 4 is bent and crosses the bent portion 3a of the waveguide 3 exactly at the position determined at the time of element design. If the positional accuracy is poor, the light propagating through the straight waveguide 3A in FIG. 5 does not reflect off the reflecting surface 5a as designed, and the optical path cannot be changed correctly, resulting in reflection loss. Cause a decline in properties It is.

Regarding the positional accuracy of the window 4, at present, it is possible to realize fairly high-accuracy alignment by performing exposure using an electron beam in the photolithography technology, for example. .

The second factor relates to the perpendicularity of the cut surface (reflective surface) 5a formed in the concave portion 5 in FIG. 5, and when the perpendicularity is poor, the same as in the case of the first factor As described above, the correct optical path change is not realized on the reflection surface 5a, and the reflection loss characteristic is reduced.

If only the process of forming the bent waveguide and the process of forming the reflective portion are performed individually, the constituent materials of the element substrate, the etching gas to be used, etc. should be appropriately selected, and the etching conditions should be optimized. Thereby, the etched surface can be made substantially perpendicular.

However, when the above two steps are performed consecutively, regardless of which step precedes, for example, the verticality at the cut surface 5a of the concave portion 5 shown in FIG. I will.

The third factor is a problem relating to the smoothness of the cut surface 5a of the formed concave portion 5 in FIG. When the smoothness, that is, the morphology characteristic is reduced, the reflection loss characteristic when the light propagating in the linear waveguide 3A changes the optical path to the linear waveguide 3B is reduced. That is, the light that has propagated to the cut surface (reflection surface) 5a has a certain light intensity spread around the optical axis of the linear waveguide 3A. Therefore, when this light is reflected by the cut surface 5a to change the optical path, the cut surface 5a is sensitive as a light beam having a certain light intensity spread, and reflects the light beam toward the linear waveguide 3B. .

At this time, if the smoothness of the cut surface 5a is inferior, that is, if the cut surface 5a is a rough surface having irregularities, the above light beam is partially reflected by the cut surface 5a. Therefore, the reflection loss characteristic is deteriorated.

Therefore, it is necessary to increase the smoothness of the cut surface 5a of the concave portion 5, but it is difficult to realize this by the above-mentioned conventional method. The reason is explained below.

First, FIG. 6 is a perspective view of the element substrate on which the resist mask 2b shown in FIG. 4 is formed as viewed from the window 4. FIG.

When this window 4 is formed by one photolithography technique, the entirety of the already formed bent waveguide 3 and the exposed surface of the upper cladding layer 1e is covered, and a predetermined resist is once applied. After the application, for example, only a portion corresponding to the window 4 to be formed is irradiated with an exposure beam, and the portion is etched and removed.

At this time, since the corner 3b of the bent portion of the bent waveguide 3 has a predetermined thickness, the exposure beam to be irradiated is used. The focus of the system is either the position of the upper surface 3c of the corner 3b to be cut by the subsequent dry etching technique, the position of the lower surface of the corner 3b, that is, the position of the exposed surface of the upper cladding layer 1e, or It has to be adjusted to the position of the depth in the middle. That is, it is absolutely impossible to simultaneously focus the exposure beam on both the surface 3c of the corner 3b and the surface of the upper cladding layer 1e.

This causes the morphological characteristics of the etching surface on the side 4 a side of the formed window 4 to deteriorate.

For example, when irradiating the resist applied to the entire surface of the element substrate with the exposure beam, the focal point is set to the depth of the surface 3c of the corner, and etching is performed. As shown, the resist on the corner surface 3c is removed by forming an etching surface with good smoothness. However, since the exposure beam is not focused near the surface of the upper cladding layer 1e located below, the etched surface formed there tends to be a rough surface 2c having irregularities. . When the exposure beam is focused on the surface of the upper cladding layer 1e, the etched surface on the corner surface 3c is roughened, contrary to the above case.

In any case, when the exposed portion of the window 4 is then removed by a drying technique to form a reflecting portion (recess) 5 as shown in FIG. Since the rough surface 2c is formed in a projected state as it is, the reflecting surface 5a does not become a smooth surface as a whole, and its morphological characteristics deteriorate.

In addition, in the conventional method, regardless of whether the process of forming the bent waveguide 3 or the process of forming the reflection portion is performed first, the thickness of the bent waveguide is applied to the beam irradiation surface during the final dry etching. Since a step corresponding to the step is always formed, the reactive ion beam, for example, tends to be scattered on the irradiation surface under the influence of the step. Then, due to the irregular reflection, the formed reflecting surface is roughened, and the morphological characteristics are inevitably reduced.

An object of the present invention is to provide a reflective waveguide having excellent morphological characteristics of the reflective surface of the formed reflective portion regardless of the order of the process of forming the bent waveguide and the process of forming the reflective portion. A method for manufacturing a waveguide element is provided.

Another object of the present invention is therefore to provide a method of manufacturing a reflective waveguide device having excellent reflection loss characteristics in a reflective portion.

Still another object of the present invention is to provide a method of manufacturing a reflective waveguide device in which the degree of freedom in selecting an etching gas to be used and the degree of freedom in etching conditions are increased, so that the degree of freedom in the manufacturing process is large. That is.

Disclosure of the invention In order to achieve the above object, in the present invention, there is provided a method for manufacturing a reflective waveguide device comprising:

By applying a photolithography technique and a dry etching technique to an element substrate formed by laminating a plurality of layers made of a dielectric or a compound semiconductor, an angle α (where α is 0 °) is applied to the element substrate. <α <180 °), a bent waveguide having a bent portion bent at (α <180 °), and a reflecting portion having a cut surface when a part of a corner of the bent portion is cut as a reflecting surface. Forming an optical path changing portion; the step of forming the optical path changing portion includes: forming a planar pattern of the bent waveguide; having at least a larger area than the planar pattern of the reflecting portion, and similar to the planar pattern of the reflecting portion. Forming a resist mask having a composite planar pattern in which the similar planar pattern overlaps partially at the bent portion of the planar pattern of the bent waveguide, on the element substrate; A step of forming a lid portion having the same plane pattern as the composite plane pattern on the element substrate by performing etching (hereinafter referred to as a step Α); and a step of forming the same plane pattern as the plane pattern of the reflection section. Forming a resist mask having the same plane pattern as the plane pattern of the reflection portion on the element substrate by performing dry etching after forming the resist mask on the element substrate (hereinafter, referred to as B ) Is provided. In the present invention described above, the step A is a step of forming a bent portion around the waveguide on the prepared element substrate, and the step B is a step of forming a concave portion functioning as a reflecting portion. is there. The order of the steps A and B is not limited, and the step A may be performed first, and then the step B may be performed, or vice versa. In any case, the object of the present invention can be achieved.

First, in the case of process A, a resist mask of a composite planar pattern in which the planar pattern of the bent waveguide formed in the optical path changing portion and the planar pattern of the reflecting portion where one side intersects at the bent portion is overlapped. Are formed on the device substrate by photolithography.

Figs. 7 and 8 show an example of the composite plane pattern of the resist mask at this time. Each of the combined plane patterns _{C l} and C 2 shown in FIGS. 7 and 8 is a two-line waveguide in which the plane pattern of the bent waveguide to be formed in the optical path changing section is bent at an angle α. The corresponding flat pattern 6 is formed, and the flat patterns 7, 7 'of the reflection portion located at the bent portion 6a form a triangle, and the long sides 7a, 7'a of the flat pattern 6 correspond to the triangular shape. It has a shape that crosses the bent part 6a diagonally. That is, in these composite plane patterns C 1 (C ₂ ), the corners 6 b of the plane pattern 6 overlap with the plane pattern 7 (7,). Each of the long sides 7 a and 7 ′ a of the plane patterns 7 and 7 ′ is a straight line orthogonal to the bisector of the angle of each plane pattern 6, and the side part of the plane pattern 6. It is a straight line that does not cross four times.

That is, the long sides 7a and 7'a obliquely cross the bent portion 6a at a portion between the inner bent portion 6c and the outer bent point 6d of the bent portion 6a. If such a mode is not adopted, it is impossible to change the light path of the light incident on one straight waveguide toward the other straight waveguide in the formed bent waveguide. .

Note that the composite plane pattern C, in FIG. 7 shows a case where the plane pattern 7 corresponding to the reflection section has the same shape as the plane pattern of the reflection section to be formed. synthesis plane pattern C ₂ illustrates a case where the area is in larger similar figure than the planar pattern of the reflective portion to be formed flat pattern 7 'corresponding to the reflective portion. This latter mode is preferable because the concave portion can be formed with high precision in the step B described later.

The composite plane pattern C! When (C ₂ ) is formed and a dry etching technique is applied thereon, the portion where the composite plane pattern (C ₂ ) is not formed is removed by etching, and as a result, it should be formed on the element substrate. A lid portion having a planar pattern in which the bent waveguide and the reflection portion are combined is formed. As described above, in the process A, a plane pattern in which the bent waveguide and the reflecting portion are united with accurate alignment is formed by applying the dry etching technique once. In other words, the positional accuracy between the bent waveguide and the reflection section is high at this point.

The process B is a process of forming a concave portion to be a reflection portion. A description will be given of a case where the present invention is applied to the bridge portion formed as described above. A resist mask is formed by photolithography at locations other than the part, and then dry etching is applied. As a result, only the portion of the reflecting portion to be formed is removed by etching, and a concave portion having a predetermined depth is formed there.

At this time, the upper surface of the corner to be cut away from the bent portion of the bent waveguide to be formed is exposed as a flat cap layer without being exposed with a step as in the case shown in FIG. . Therefore, the irradiated reactive ion beam, for example, can sequentially etch a flat surface and gradually deepen a concave portion.

As a result, as in the case of the dry etching of the element substrate shown in FIG. 6, the mismatch of the beam focus and the irregular reflection of the beam due to the presence of the step between the corner 3b and the upper cladding layer 1e do not occur, and the formation does not occur. Each etched surface (wall surface of the reflective portion) of the recessed portion becomes smooth, and its morphological characteristics are improved. You.

Similar effects can be obtained when the process B is performed first. That is, first, a photolithography technique is applied to the element substrate to form a resist mask having a plane pattern excluding a reflection portion to be formed, and then a dry etching technique is applied thereto. When a concave portion having a predetermined depth is formed by etching, a portion corresponding to a corner to be cut in the bent waveguide to be formed is also removed at that time. At this time, the etched surface (wall surface of the reflecting portion) is a smooth surface for the same reason as described above.

Next, a resist mask having the composite plane pattern described above is formed on the obtained element substrate. At this time, the above-mentioned concave portion is also filled with the mask resist.

In this state, proceed to step A. Since the recesses are filled with a mask resist, the walls of the recesses that become the reflecting surfaces during the formation of the edge are roughened due to the application of the dry etching technology during the process A. There is no.

Brief explanation of drawings

FIG. 1 is a perspective view showing an example of an element substrate used for manufacturing a reflective waveguide element; FIG. 2 is an oblique view showing a state in which a bent waveguide resist mask is formed on the element substrate. Perspective view; FIG. 3 is a perspective view showing a state in which a bent waveguide is formed; FIG. 4 is a resist mask for a reflecting portion formed FIG. 5 is a perspective view showing a reflecting portion formed by dry etching; FIG. 6 is a perspective view of the element substrate shown in FIG. 4 when viewed from a window; 7 is a plan view showing a combined plane pattern of a resist mask formed by the present invention; FIG. 8 is a plan view showing another combined plane pattern of a resist mask; FIG. 9 is a plan view showing a combined plane pattern on an element substrate. FIG. 10 is a perspective view showing a state in which a resist mask is formed; FIG. 10 is a perspective view showing a state in which a lid portion is formed by applying a dry etching technique; FIG. FIG. 12 is a perspective view showing a state in which a resist mask is formed; FIG. 12 is a perspective view of a manufactured reflective waveguide device; FIG. 13 is a resist mask formed on an element substrate for a reflective portion; Perspective view showing the condition; Fig. 14 is a dry etch FIG. 15 is a perspective view showing a state in which a concave portion is formed by applying a polishing technique; FIG. 15 is a perspective view showing a state in which a resist mask having a combined plane pattern is formed on an element substrate; and FIG. Is a perspective view showing another manufactured reflection type waveguide element.

Example

Example 1

First, an element substrate 1 having a layer structure as shown in FIG. 1 was prepared. A resist is applied to the cap layer 1 f of the element substrate 1 and a photolithography technique is applied thereto, thereby forming a resist having a composite plane pattern as shown in FIG. A mask 8 is formed.

As shown in FIG. 8, the plane pattern of the resist mask 8 is a similar plane pattern in which the plane pattern 7 'corresponding to the reflection section has a larger area than the plane pattern of the reflection section to be formed. The angle α at the bent part of the plane pattern 6 is 90 °, and the long side of the similar plane pattern 7 ′ is obliquely crossing the bent part at an angle of 45 °. I have.

The device substrate is set in an RIΒ device, and reactive ions are irradiated from above the plane pattern 8 to etch away a predetermined thickness portion of the upper cladding layer 1e, and then the resist mask 8 is removed. .

As a result, as shown in FIG. 10, on the remaining upper clad layer 1e, a ridge-shaped bend in which the plane pattern has the same shape as the plane pattern 6 of the resist mask 8 is formed. A ridge portion 10 having a shape in which the waveguide 3 and a ridge-like convex portion 9 having the same shape as the similar planar pattern 7 ′ of the resist mask are combined is formed. The upper surface of the lid 10 is the surface of the cap layer 1f itself, and the same horizontal plane is formed between the bent waveguide 3 and the projection 9.

Next, a resist is applied on the upper lid portion 10 and the exposed upper cladding layer 1e by photolithography technology, and then the resist is formed as shown in FIG. Be A resist mask 11 is formed in which a window 4 having a pattern corresponding to the planar pattern of the reflective portion is located above the convex portion 9. That is, the surface of the cap layer 1 f is exposed from the window 4 of the resist mask 11.

The element substrate shown in FIG. 11 is set in a RIBE apparatus, and the upper surface of the resist mask 11 is irradiated with a reactive ion so that the portion exposed from the window 4 becomes the buffer layer 1 b or the substrate. After etching and removing to a depth where 1a is exposed, the resist mask 11 is removed.

As a result, as shown in FIG. 12, the depth reaches the surface of the buffer layer 1 b (or the substrate 1 a) at a predetermined position of the convex portion 9, and the bent portion 3 of the bent waveguide 3 is formed. A concave portion 5 formed by cutting off a corner in a is formed.

The wall surface 5a of the concave portion 5 constitutes a reflecting surface of the bent waveguide 3. The bent waveguide 3 and the concave portion (reflecting portion) 5 having the reflecting surface 5a are joined together to form an optical path changing portion. Is formed.

Since the concave portion 5 is formed by applying a dry etching technique to a flat surface having no step, the beam focus shift and irregular reflection due to the step do not occur. Therefore, the smoothness of the etched surface, that is, the wall surface (reflection surface) 5a becomes excellent.

Example 2

Next, an embodiment in which the step B is performed first will be described. First, an element substrate 1 having a layer structure as shown in FIG. 1 is prepared. After applying a resist to the cap layer 1 f of the element substrate 1 and applying photolithography technology, the planar pattern becomes a square as shown in FIG. 13. A resist mask 12 having a window 4 is formed.

Then, the device substrate is set in, for example, a RIBE apparatus, and a beam of reactive ions is irradiated from above the resist mask 12 so that the portion exposed from the window 4 is covered with the buffer layer lb or the substrate la. O Remove the resist mask 12 after etching to the depth where

As a result, as shown in FIG. 14, the depth reaches the surface of the buffer layer 1b (or the substrate 1a) at a predetermined location of the element substrate 1, and the bent waveguide to be formed is bent. A concave portion 5 is formed in which a corner to be cut from the curved portion is cut. "

At this time, each of the etched surfaces of the concave portion 5, that is, each of the wall surfaces is formed by sequentially dry-etching a flat surface without any step, so that the beam defocus and irregular reflection occur during the dry etching process. As a result, the surface is formed as a surface having excellent smoothness.

Next, a mask resist is applied to the entire surface of the element substrate shown in FIG. As shown in FIG. 5, a planar pattern of the bent waveguide to be formed and a similar planar pattern overlapping the bent portion and having a larger area and a similar shape than the planar pattern of the recess 5 described above. A resist mask 13 having a composite plane pattern composed of When the resist mask 13 is formed, the concave portion 5 shown in FIG. 14 is also filled with the mask resist.

In the resist mask 13, the bending angle of the bending portion in each plane pattern corresponding to the two linear waveguides is set to 45 °.

Then, the element substrate is set in, for example, a RIBE apparatus, and the resist mask is irradiated with a beam of reactive ions from above the resist mask 13 until a predetermined thickness of the upper cladding layer 1 e is removed. The portions where the resist mask 13 is not formed are removed by etching, and finally the resist mask 13 is removed.

As a result, as shown in Fig. 16, a ridge-shaped bent waveguide 3 was formed on the remaining upper cladding layer 1e, and at the same time, was exposed again by removing the resist mask. An optical path changing portion including a reflecting portion composed of the recessed portion 5 and a frame portion surrounding and projecting in a dike shape around the recessed portion 5 is formed.

In this dry etching process, the already formed reflecting surface 5a is filled with the resist Because it is covered with a mask, the smooth state when initially formed is maintained.

Industrial applicability

In the method of manufacturing a reflective waveguide device according to the present invention, a combined pattern in which a planar pattern of a bent waveguide to be formed and a planar pattern of a reflective portion to be formed in the bent portion or a pattern similar thereto is combined. Since a flat pattern is formed on the element substrate using photolithography technology and dry etching technology is applied, the dry etching technology can be used regardless of whether the bent waveguide formation process or the reflection portion formation process is performed first. Is applied to a flat surface with no steps, and as a result, the morphological characteristics of the etched surface (reflection surface) at the bent portion become excellent.

Therefore, the reflection type waveguide element manufactured by the method of the present invention has good reflection loss characteristics at the reflection portion, and its propagation characteristics are improved.

Further, according to the method of the present invention, it is easy to select the type of the etching gas and the optimum etching conditions at the time of dry etching, and the degree of freedom of the manufacturing process is increased.

Claims

The scope of the claims

A method for manufacturing a reflective waveguide device comprising:

By applying a photolithography technique and a dry etching technique to an element substrate formed by laminating a plurality of layers made of a dielectric or a compound semiconductor, the element substrate has an angle α (where α is 0 ° <α). (180 °)), an optical path change comprising a bent waveguide having a bent portion bent at (180 °) and a reflecting portion having a cut surface as a reflecting surface when a part of a corner of the bent portion is cut. Forming a part;

In the step of forming the optical path changing portion, the bent waveguide planar pattern and at least the similar planar pattern having a larger area than the reflective portion planar pattern and similar to the reflective portion planar pattern are bent. After forming a resist mask having a composite plane pattern that partially overlaps the bent portion of the plane pattern of the waveguide on the element substrate, dry etching is performed, and the composite plane pattern is formed on the element substrate. Forming a lid portion having the same planar pattern as;

A resist mask having the same plane pattern as the plane pattern of the reflection section is formed on the element substrate, and then dry etching is performed on the element substrate to form the same plane as the plane pattern of the reflection section. Forming an ω portion having a pattern;

It is included.

2. The method of manufacturing a reflective waveguide device according to claim 1, wherein the step of forming the lid portion is performed prior to the step of forming the concave portion.

The method for manufacturing a reflective waveguide device according to claim 1, wherein the step of forming the concave portion is performed prior to the step of forming the lid portion.

In the resist mask having the composite planar pattern, at a place where the similar planar pattern and the planar pattern of the bent waveguide overlap each other, the side of the similar planar pattern is the same as the planar pattern of the bent waveguide. 2. The method for manufacturing a reflective waveguide device according to claim 1, wherein the angle is perpendicular to a bisector of an angle of the bent portion.