Optical semiconductor element, optical integrated element, and method for manufacturing optical semiconductor element

Abstract

To obtain a novel improved optical semiconductor element and an optical integrated element capable of securing a positioning accuracy between the optical semiconductor element and a component different from the optical semiconductor element more easily or more reliably, and to obtain a method of manufacturing the optical semiconductor element.SOLUTION: An optical semiconductor element comprises: a substrate; a first protruding part; and a second protruding part that functions as a positioning part used for positioning with a component different from the optical semiconductor element. The optical semiconductor element includes a first semiconductor layer formed over a first portion behind the first protruding part in a first direction, a second portion behind the second protruding part in the first direction, and a third portion between the first and second portions. The first semiconductor layer is not etched by a predetermined etchant capable of etching the other semiconductor layer, or alternatively, has a sufficiently small ratio of an etching rate to an etching rate of the other semiconductor layer.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an optical semiconductor device, an optical integrated device, and a method for manufacturing an optical semiconductor device. [Background technology]

[0002] Conventionally, optical integrated elements have been known that integrally include an optical semiconductor element such as a semiconductor laser element or a semiconductor optical amplifier and a portion having a waveguide (hereinafter, this portion will be referred to as an optical functional element) (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-92262 Summary of the Invention [Problem to be solved by the invention]

[0004] In this type of optical integrated element, it would be beneficial if the alignment accuracy between the optical semiconductor element and a component different from the optical semiconductor element, such as an optical functional element, could be more easily or more reliably ensured.

[0005] Therefore, one object of the present invention is to provide a new and improved optical semiconductor element, optical integrated element, and method for manufacturing an optical semiconductor element, which can more easily or more reliably ensure the alignment accuracy between an optical semiconductor element and a component other than the optical semiconductor element. [Means for solving the problem]

[0006] The optical semiconductor element of the present invention comprises, for example, a substrate extending intersecting a first direction, a first protruding portion protruding from the substrate in the first direction and having a semiconductor layer including an active layer, and a second protruding portion protruding from the substrate in the first direction at a position spaced from the first protruding portion in a second direction intersecting the first direction, having a semiconductor layer and functioning as a positioning portion used for positioning a component other than the optical semiconductor element, and includes a first semiconductor layer formed across a first portion rearward of the first protruding portion in the first direction, a second portion rearward of the second protruding portion in the first direction, and a third portion between the first portion and the second portion, and which is not etched by a predetermined etchant capable of etching other semiconductor layers or has an etching rate whose ratio of the etching rate to the etching rate of the other semiconductor layers is sufficiently small.

[0007] In the optical semiconductor element, the active layer and the first semiconductor layer may be spaced apart in the first direction by a distance that allows them to be optically isolated from each other.

[0008] In the optical semiconductor element, the protrusion height of the second protrusion in the first direction from the first recess between the first protrusion and the second protrusion may be smaller than the protrusion height of the first protrusion in the first direction from the first recess.

[0009] In the optical semiconductor element, the second protrusion may include, at a position spaced apart in the first direction from the first semiconductor layer, a second semiconductor layer that is not etched by a predetermined etching solution or etching gas that can etch other semiconductor layers, or that has an etching rate whose ratio to the etching rate of the other semiconductor layers is sufficiently small.

[0010] In the optical semiconductor element, the second semiconductor layer may have the same components as the active layer and be aligned with the active layer in the second direction.

[0011] In the optical semiconductor element, the first protrusion may include a first mesa in which a plurality of semiconductor layers including the active layer are stacked, and the second protrusion may include a second mesa having at least a portion of the same stack structure as the first mesa.

[0012] The optical semiconductor element may include a waveguide that includes the active layer and has a curved shape when viewed in a direction along the first direction.

[0013] In the optical semiconductor element, the waveguide may have a U-shaped bend when viewed in the first direction.

[0014] The optical semiconductor element may include a plurality of second protrusions as the second protrusion.

[0015] In the optical semiconductor element, the first protrusion may be located between the plurality of second protrusions.

[0016] In the optical semiconductor element, the second protrusion may be used for positioning with an optical functional element having an optical waveguide including a core.

[0017] In the optical semiconductor element, the second protrusion may be used for positioning with the optical functional element in the first direction.

[0018] In the optical semiconductor element, the second protrusion may be used for positioning the optical functional element in a direction intersecting the first direction.

[0019] The optical semiconductor element may include a plurality of first protrusions as the first protrusion.

[0020] In the optical semiconductor element, the second protrusion may be located between the plurality of first protrusions.

[0021] In the optical semiconductor element, a second recess may be provided between the plurality of first protrusions, the second recess having approximately the same depth as a first recess between the first protrusion and the second protrusion.

[0022] The optical integrated element of the present invention comprises, for example, an optical functional element having an optical waveguide including a core, and the optical semiconductor element, wherein the optical functional element has a contact portion located on the opposite side of the second protrusion from the substrate and in contact with the second protrusion, and the core and the active layer face a third direction intersecting the first direction.

[0023] A method for manufacturing an optical semiconductor element of the present invention includes, for example, the steps of: forming a stacked structure in which a plurality of semiconductor layers are stacked in a first direction on a substrate, the plurality of semiconductor layers including a first semiconductor layer that is not etched by a predetermined etching solution or etching gas that can etch other semiconductor layers or that has an etching rate that is sufficiently small relative to the etching rate of the other semiconductor layers; forming a plurality of mesas protruding from the substrate at a plurality of locations spaced apart in a second direction that intersects with the first direction by partially removing the stacked structure on a side opposite to the substrate; forming a current blocking layer so as to fill the spaces between the plurality of mesas; and forming a first protruding portion including a first mesa that is one of the plurality of mesas and a portion of the current blocking layer adjacent to the first mesa, and a second protruding portion including a second mesa of the plurality of mesas that is different from the first mesa, by etching with the etching solution or etching gas that uses the first semiconductor layer as an etching stop layer. [Effects of the Invention]

[0024] According to the present invention, new and improved optical semiconductor devices, optical integrated devices, and methods for manufacturing optical semiconductor devices can be provided. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is an exemplary schematic plan view of an optical semiconductor element according to the first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II of FIG. [Figure 3] FIG. 3 is an exemplary schematic side view of the optical integrated device according to the first embodiment. [Figure 4] FIG. 4 is an exemplary schematic cross-sectional view of a product during the manufacturing process of the optical semiconductor element of the first embodiment. [Figure 5] FIG. 5 is an exemplary schematic cross-sectional view of a product during the manufacturing process of the optical semiconductor element of the first embodiment at a stage subsequent to that of FIG. [Figure 6] FIG. 6 is an illustrative schematic cross-sectional view of a product during the manufacturing process of an optical semiconductor device of a reference example, at the same stage as FIG. [Figure 7] FIG. 7 is an illustrative schematic plan view of the optical semiconductor element according to the second embodiment. [Figure 8] FIG. 8 is an illustrative schematic plan view of the optical semiconductor element according to the third embodiment. [Figure 9] FIG. 9 is an illustrative schematic plan view of the optical semiconductor element according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] Exemplary embodiments of the present invention are disclosed below. The configurations of the embodiments described below, as well as the actions and results (effects) brought about by the configurations, are merely examples. The present invention can also be realized by configurations other than those disclosed in the following embodiments. Furthermore, according to the present invention, it is possible to obtain at least one of the various effects (including derivative effects) obtained by the configurations.

[0027] The following embodiments have similar configurations. Therefore, the configurations of the respective embodiments provide similar actions and effects based on the similar configurations. In the following, the similar configurations are given the same reference numerals, and redundant explanations may be omitted.

[0028] In this specification, ordinal numbers are given for convenience to distinguish directions, parts, etc., and do not indicate priority or order.

[0029] In each figure, the X direction is represented by an arrow X, the Y direction is represented by an arrow Y, and the Z direction is represented by an arrow Z. The X direction, Y direction, and Z direction intersect with each other and are perpendicular to each other. In the following, the X direction will be referred to as the longitudinal direction or extension direction, the Y direction will be referred to as the lateral direction or width direction, and the Z direction will be referred to as the stacking direction or height direction.

[0030] Furthermore, each figure is a schematic diagram for the purpose of explanation, and the scale and ratio of each figure do not necessarily match those of the actual product.

[0031] [First embodiment] Fig. 1 is a plan view of an optical semiconductor device 100A (100) according to the first embodiment, and Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. The optical semiconductor device 100A is configured as a known semiconductor optical amplifier.

[0032] As shown in FIGS. 1 and 2, the optical semiconductor element 100A includes a substrate 10, a protruding portion 11, and protruding portions 12 (12V, 12H).

[0033] Protrusions 11 and 12 protrude from substrate 10 in the Z direction. Protrusions 11 and 12 are spaced apart in the Y direction. Protrusion 11 is an example of a first protrusion, and protrusion 12 is an example of a second protrusion. The Z direction is an example of a first direction, and the Y direction is an example of a second direction.

[0034] The protruding portion 11 is a portion that functions as, for example, a semiconductor optical amplifier, and may also be referred to as a functional portion.

[0035] As shown in FIG. 1, the protrusion 11 extends in the X direction. The protrusion 11 contains an active layer 21a serving as an optical waveguide. The active layer 21a extends substantially along the X direction. However, the active layer 21a is inclined with respect to the X and Y directions near an end 21a1 in the X direction and an end 21a2 opposite the X direction. This prevents light reflected at the ends 21a1 and 21a2 from returning to the waveguide path. The protrusion 11 has a buried waveguide structure (BH waveguide structure).

[0036] The optical semiconductor element 100A has two protrusions 12V and four protrusions 12H as the protrusions 12. The protrusions 12 are portions used for positioning components other than the optical semiconductor element 100 (hereinafter referred to as other components), such as the optical functional element 200 (see FIG. 3), and may also be referred to as positioning portions.

[0037] As shown in FIG. 1 , two protrusions 12V are provided in front of and behind the protrusion 11 in the Y direction, spaced apart from the protrusion 11. The protrusion 12V extends in the X direction with a substantially constant width in the Y direction and a substantially constant height in the Z direction. The protrusion 12V is used, for example, to position the optical semiconductor element 100A and the optical functional element 200 in the Z direction. Positioning using the protrusion 12V is achieved, for example, by contact between the optical semiconductor element 100A and the optical functional element 200. In this case, the Z-direction end 12a of the protrusion 12V faces the Z direction and is a plane intersecting the Z direction. The end 12a may also be referred to as an end face or a contact surface. Note that when the optical semiconductor element 100A is supported by another component via the protrusion 12V, the length of the protrusion 12V in the X direction is preferably at least one-third of the length of the optical semiconductor element 100 and the protrusion 11 in the X direction, from the viewpoint of support stability.

[0038] On the other hand, the four protrusions 12H are provided near the end of the optical semiconductor element 100A in the X direction or the end opposite the X direction. Of the four protrusions 12H, the two protrusions 12H located at the end in the X direction are provided in front of and behind the protrusion 11 with a gap in the Y direction from the protrusion 11. Furthermore, of the four protrusions 12H, the two protrusions 12H located at the end opposite the X direction are also provided in front of and behind the protrusion 11 with a gap in the Y direction from the protrusion 11. The protrusions 12H are used to position the optical semiconductor element 100A and the optical functional element 200 in the X and Y directions, i.e., in a direction intersecting the Z direction. Specifically, the positioning in the X and Y directions using the protrusions 12H is performed, for example, by image recognition or image analysis of an image of the protrusions 12H captured by a camera.

[0039] However, the shape, number, arrangement, etc. of the protrusions 12V and 12H are not limited to the example in Fig. 1. The protrusions 12V and 12H may be provided one by one, or a protrusion in which the protrusions 12H and 12V are integrated may be provided.

[0040] The substrate 10 has a substantially constant thickness in the Z direction and extends in a direction intersecting the Z direction. As shown in FIG. 2, the substrate 10 has a surface 10a and a surface 10b. The surface 10a faces the Z direction and intersects the Z direction. The surface 10b is located on the opposite side of the surface 10a, faces the opposite direction to the Z direction, and intersects the Z direction. The substrate 10 is made of, for example, n-InP.

[0041] The protruding portion 11 includes a mesa 21, and the protruding portion 12 includes a mesa 22. The mesa 21 is an example of a first mesa, and the mesa 22 is an example of a second mesa.

[0042] The mesas 21 and 22 are fabricated using the same semiconductor process. Therefore, the mesas 21 and 22 include the same stacked semiconductor layers (first layer 20a to third layer 20c) and have partially the same stacked structure. That is, the same semiconductor layers included in the mesas 21 and 22 are made of the same material, are aligned in the Y direction, and are located at the same position in the Z direction from the surface 10a of the substrate 10. However, because the Z-direction end of the mesa 22 is removed by etching, the Z-direction end of the mesa 21 includes a semiconductor layer (fourth layer 20d) that is not included in the mesa 22.

[0043] The first layer 20a is made of, for example, n-InGaAsP. The first layer 20a is a so-called quaternary layer, and is either not etched by a specific etchant, such as an etching solution (e.g., hydrochloric acid) or an etching gas, that can etch other semiconductor layers (e.g., cladding layers made of InP), or has a property that the ratio of the etching rate of the first layer 20a to the etching rate of other semiconductor layers is sufficiently small (e.g., 1 / 10 or less). The first layer 20a functions as an etching stop layer when forming the recess 13 by etching. The thickness of the first layer 20a is, for example, about 20 nm. The first layer 20a is an example of a first semiconductor layer. The recess 13 is also an example of a first recess.

[0044] This first layer 20a is formed widely on the surface 10a of the substrate 10, for example, so as to cover substantially the entire surface 10a, and includes a portion 20a1 that is rearward in the Z direction from the protrusion 11, a portion 20a2 that is rearward in the Z direction from the protrusion 12V (12), and a portion 20a3 that is rearward in the Z direction from the recess 13 between the protrusions 11 and 12. Although not shown in FIG. 2, the first layer 20a also includes a portion that is rearward in the Z direction from the protrusion 12H, a portion that is rearward in the Z direction from the recess 13 between the protrusions 11 and 12H, a portion that is rearward in the Z direction from the recess 13 between the protrusions 12V and 12H, and, in a configuration including multiple protrusions 11, a portion that is rearward in the Z direction from the recess 14 (see FIG. 8) between the multiple protrusions 11. These portions and portions 20a1, 20a2, and 20a3 are formed continuously without interruption. Therefore, it can also be said that the protrusions 11, 12 (12V, 12H) protrude in the Z direction from the first layer 20a. The portion 20a1 is an example of a first portion, the portion 20a2 is an example of a second portion, and the portion 20a3 is an example of a third portion.

[0045] The second layer 20b is made of, for example, n-InP, and functions as a cladding layer in the mesa 21.

[0046] The third layer 20c has a layered structure containing, for example, n-InGaAsP, and is a so-called quaternary layer. The third layer 20c included in the mesa 21 functions as the active layer 21a. To function as the active layer 21a, the third layer 20c has a composition that functions appropriately for light in the 1.55 μm wavelength band, for example.

[0047] On the other hand, the third layer 20c included in the mesa 22 functions as an etching stop layer (mask) when the mesa 22 is formed by etching and when the recess 13 is formed by etching. The third layer 20c included in the mesa 22 has the same components as the active layer 21a and is aligned with the active layer 21a in the Y direction. The third layer 20c is an example of a second semiconductor layer. Note that the mesa 22 may include a second semiconductor layer that functions as an etching stop layer (mask) in addition to the third layer 20c.

[0048] The mesa 22 constitutes the protruding portion 12. In the mesa 22, the protruding portion 12 is covered with the insulating layer 20h, but it does not have to be covered.

[0049] The protruding portion 11 also has a fourth layer 20d, current blocking layers 20e and 20f, and a cladding layer 20g as semiconductor layers that are not included in the protruding portion 12 (mesa 22).

[0050] The fourth layer 20d is made of, for example, p-InP, and functions as a cladding layer in the mesa 21.

[0051] In the protrusion 11, the mesa 21 is surrounded by a fifth layer 20j and current blocking layers 20e and 20f adjacent in the Y direction and the direction opposite to the Y direction, and a cladding layer 20g adjacent in the Z direction. The fifth layer 20j is made of the same material as the second layer 20b. The current blocking layer 20e is made of, for example, p-InP, and the current blocking layer 20f is made of, for example, n-InP. The cladding layer 20g is made of, for example, p-InP.

[0052] An electrode 31 is provided on the opposite side of the substrate 10 from the cladding layer 20g. The electrode 31 is a P-side electrode and is spaced apart from the active layer 21a in the Z direction. The electrode 31 has a layered structure including, for example, a contact layer, a base layer, a barrier layer, a thick film layer, etc. (none of which are shown).

[0053] The end faces (side faces) of the protrusions 11 and 12 in the Y direction and the direction opposite to the Y direction, as well as the end faces (top faces) in the Z direction, are covered with an insulating layer 20h, except for an opening on the protrusion 11 through which the electrode 31 penetrates. The insulating layer 20h is made of, for example, SiN.

[0054] An electrode 32 is provided on the surface 10b of the substrate 10. The electrode 32 is an N-side electrode and has a layered structure containing, for example, AuGe, Ni, and Au.

[0055] (Structure of optical functional elements and optical integrated elements) Fig. 3 is a side view of a portion of an optical integrated device 300 including an optical semiconductor device 100 and an optical functional device 200. Fig. 3 shows a state in which the optical semiconductor device 100 and the optical functional device 200 are aligned. As shown in Fig. 3, in the optical integrated device 300, the optical semiconductor device 100 and the optical functional device 200 overlap in the Z direction. The optical functional device 200 may also be referred to as a silicon platform.

[0056] The optical functional element 200 has a base 201, a protrusion 202, and a body 203. The protrusion 202 protrudes from a surface 201a of the base 201 in the opposite Z direction. The body 203 also protrudes from the surface 201a in the opposite Z direction. An optical waveguide including a core 203a extending in the X direction is provided within the body 203. In the optical integrated element 300, when the optical semiconductor element 100 and the optical functional element 200 are aligned as shown in FIG. 3, an end face 203b of the body 203 facing the opposite X direction faces an end face 11c of the optical semiconductor element 100 in the X direction, and an end 21a1 of the active layer 21a and an end 203a1 of the core 203a face the X direction and are aligned in the X direction. With this configuration, the end 21a1 and the end 203a1 are optically coupled. The X direction is an example of a third direction.

[0057] As described above, in this embodiment, the mesa 21 included in the protruding portion 11 and the mesa 22 included in the protruding portion 12V have partially the same stacked structure in the Z direction. Therefore, by setting the Z-direction height of the protruding portion 12V with respect to the third layer 20c in the protruding portion 12V, i.e., the position of the end portion 12a in the Z direction, it is possible to set the Z-direction height of the protruding portion 12V with respect to the active layer 21a in the mesa 21 within the protruding portion 11, i.e., the position of the end portion 12a in the Z direction. Therefore, according to this embodiment, the active layer 21a of the optical semiconductor element 100 and the core 203a of the optical functional element 200 can be aligned in the Z direction more easily or with greater accuracy, thereby achieving the effect of more easily or more reliably suppressing a decrease in optical coupling efficiency between the active layer 21a and the core 203a.

[0058] In this embodiment, the optical semiconductor element 100 includes a plurality of protrusions 12V. Furthermore, the protrusions 11 are located between the plurality of protrusions 12V. This configuration has the effect of enabling the optical semiconductor element 100 to be supported more stably by the plurality of protrusions 12V.

[0059] (Method of manufacturing an optical semiconductor element) 4 and 5 are diagrams showing products produced during each manufacturing step in the method for manufacturing the optical semiconductor device 100. FIG.

[0060] First, as shown in FIG. 4, a first layer 20a, a second layer 20b, a third layer 20c, and a fourth layer 20d are stacked on a substrate 10 serving as a wafer by crystal growth.

[0061] Next, etching (first etching) using a mask and a predetermined etching solution or etching gas is performed to selectively and partially remove portions of the product shown in FIG. 4 on the side opposite to the substrate 10, thereby forming mesas 21 and 22 spaced apart in the Y direction. Trenches (not shown) are formed around mesas 21 and 22. The first etching to form mesas 21 and 22 is performed so that the fifth layer 20j remains on the first layer 20a.

[0062] Next, current blocking layers 20e and 20f are formed to completely fill the trenches, and the mask used in the first etching is removed.

[0063] Next, cladding layer 20g, insulating layer 20m, and at least a part of electrode 31 are formed on the side of the product on which current blocking layers 20e and 20f are formed, opposite substrate 10. This results in the product shown in FIG.

[0064] 4, the region between mesa 21 and mesa 22, which is on the side opposite to substrate 10, is removed by etching (second etching) with a predetermined etching solution or etching gas using insulating layer 20m and third layer 20c in mesa 22 as an etching mask (etching stop layer), thereby forming protrusion 11 containing mesa 21 and mesa 22 (part of protrusion 12V), as shown in FIG. 5. This etching forms protrusion 11 containing mesa 21 therein and recess 13 between protrusion 11 and mesa 22. In addition, first layer 20a functions as an etching stop layer in recess 13.

[0065] After removing the insulating layer 20m, an insulating layer 20h is formed as shown in FIG. 2. The insulating layer 20h is then partially removed above the electrode 31 to form an opening. A conductor is then added to the electrode 31, extending through the opening onto the insulating layer 20h, thereby forming the electrode 31 shown in FIG. 2. Meanwhile, the end face of the substrate 10 opposite the Z direction is polished to form a surface 10b, and then an electrode 32 is formed on the surface 10b by, for example, vapor deposition lift-off. Next, ohmic contact is formed between the electrodes 31, 32, and the semiconductor layers of the protrusion 11 by heat treatment. The side surfaces of the protrusion 11 are covered with the insulating layer 20h.

[0066] The wafer (not shown) that has been subjected to the above-described processing is cleaved, and a low-reflection coating is applied to the end face 11c in the X direction and the end face 11d (see FIG. 1) opposite to the X direction, thereby completing the optical semiconductor element 100 shown in FIGS. 1 and 2.

[0067] Through intensive research by the inventors into such a configuration and process, it has been found that if the first layer 20a is not provided, there is a risk that etching residue such as the protrusion 20i shown in FIG. 6 (reference example) may be generated in the recess 13 during etching to obtain the product of FIG. 5 from the product of FIG. 4. It has been found that such etching residues cause inconveniences, such as: (1) protrusions 20i that are higher than end portions 12a interfere with the positioning of optical semiconductor element 100 in the Z direction by protrusion 12V; (2) the shape of the boundary of protrusion 12H is changed from a predetermined shape when viewed in a plan view in the opposite direction to the Z direction, interfering with image recognition or image analysis of protrusion 12H, and ultimately interfering with the positioning of optical semiconductor element 100 in the X or Y direction; and (3) the residues at the bottom of recess 13 become a path for leakage current from protrusion 11, making it impossible to apply a required amount of current from electrodes 31, 32 to active layer 21a of mesa 21.

[0068] Therefore, the inventors came up with a configuration in which a first layer 20a functioning as an etching stop layer is provided behind the recess 13 in the Z direction. With this configuration, etching can be performed until the first layer 20a is exposed in the recess 13 and etching residues such as the protrusions 20i in the recess 13 disappear. This avoids the problems (1) to (3) described above. Furthermore, since etching can be more easily controlled, it is possible to prevent excessive etching of the side surfaces of the protrusions 11 and mesas 22, which would otherwise reduce their mechanical strength. Furthermore, the first layer 20a can be formed relatively easily over substantially the entire surface 10a of the substrate 10, and the disadvantages of the configuration without the first layer 20a as shown in FIG. 6 are minimal.

[0069] Furthermore, through extensive research, the inventors have found that in the configuration of this embodiment, the distance h between the active layer 21a and the first layer 20a in the Z direction, i.e., the distance h between the third layer 20c and the first layer 20a, is 2 μm or more, thereby optically isolating the active layer 21a from the first layer 20a. This means that optical absorption of light propagating through the active layer 21a in the first layer 20a can be suppressed to a level that does not affect the desired characteristics. Furthermore, from the perspective of preventing leakage current, it is necessary to completely remove at least the current blocking layer 20e (p-InP layer). From this perspective, it has also been found that the distance h is preferably 2 μm or more. Note that, in the configuration of this embodiment, the distance h that can optically isolate the active layer 21a from the first layer 20a is 2 μm, for example. However, the value of the distance h depends on the specifications of the semiconductor layers.

[0070] As described above, according to the structure and method of this embodiment, it is possible to form the protrusion 12 with higher precision and to suppress leakage current from the protrusion 11. That is, according to this embodiment, it is possible to obtain a novel and improved optical semiconductor element 100, an optical integrated element 300, and a method for manufacturing the optical semiconductor element 100.

[0071] Furthermore, in the optical semiconductor element 100 of this embodiment, the protrusions 12 also contribute to improving the rigidity and strength of the optical semiconductor element 100. From this perspective, it is preferable that the optical semiconductor element 100 be provided with a plurality of protrusions 12, or with a long protrusion 12 such as protrusion 12V. Such protrusions 12 make the optical semiconductor element 100 less likely to deform, and can suppress an increase in optical coupling loss with other components due to such deformation.

[0072] Furthermore, in the optical integrated element 300 of this embodiment, the height of the protrusion 12 from the recess 13 is lower than the height of the protrusion 11 from the recess 13, and the end 12a of the protrusion 12 of the optical semiconductor element 100 and the end 202a of the protrusion 202 of the optical functional element 200 are in contact with each other. If the protrusion of one of the optical semiconductor element 100 and the optical functional element 200 were to be aligned by contacting the recess of the other, the other would need a peripheral wall to form a recess to accommodate the protrusion provided on the other. At the aligned portion, the protrusion and the peripheral wall would overlap in a direction intersecting the protrusion direction (stacking direction), which could increase the size of the other element in the direction intersecting the protrusion direction. In this regard, the optical integrated element 300 of this embodiment, in which the protrusion 12 and the protrusion 202 are in contact with each other, can be configured more compactly than a configuration in which the protrusion and the recess are aligned. The protrusion 202 is also referred to as a third protrusion, and the end 202a is an example of a contact portion.

[0073] [Second embodiment] 7 is a plan view of an optical semiconductor element 100B according to the second embodiment. The optical semiconductor element 100B of this embodiment has a bar (array) of multiple protrusions 11 arranged in the Y direction, each having the same configuration as the first embodiment. Two protrusions 11 adjacent to each other in the Y direction share a protrusion 12 located between the two protrusions 11.

[0074] The optical semiconductor device 100B of this embodiment also has a configuration similar to that of the optical semiconductor device 100A of the first embodiment. Therefore, this embodiment also provides the same effects as the first embodiment. Furthermore, the configuration of this embodiment, which has multiple protrusions 11 (active layers 21a), is suitable for application to optical devices having multiple semiconductor optical amplifiers, such as optical matrix switches.

[0075] [Third embodiment] 8 is a plan view of an optical semiconductor element 100C of the third embodiment. The optical semiconductor element 100C of this embodiment also has a bar (array) of multiple protrusions 11 arranged in the Y direction, with the same configuration as in the first embodiment, and has a similar configuration to the optical semiconductor element 100B of the second embodiment. However, in this embodiment, there is no protrusion 12 between two protrusions 11 adjacent in the Y direction, and positioning protrusions 12 are provided only at the end of the optical semiconductor element 100C in the Y direction and at the end opposite the Y direction. A recess 14 having approximately the same depth as the recess 13 is provided between two protrusions 11 adjacent in the Y direction. The recess 14 is an example of a second recess.

[0076] The optical semiconductor element 100C of this embodiment also has a configuration similar to that of the optical semiconductor element 100A of the first embodiment. Therefore, this embodiment also provides the same effects as the first embodiment. In addition, it provides the effect of preventing leakage current between two protrusions 11 adjacent in the Y direction through the recess 14 and the portion behind the recess 14 in the Z direction.

[0077] [Fourth embodiment] FIG. 9 is a plan view of an optical semiconductor device 100D according to a fourth embodiment. The optical semiconductor device 100D of this embodiment also includes a plurality of protrusions 11D (11) arranged in a bar (array) in the Y direction. However, this embodiment differs from the other embodiments in that the optical semiconductor device 100D includes a plurality of U-shaped waveguides in a plan view viewed in the opposite direction of the Z direction. Each waveguide includes two active layers 21a spaced apart in the Y direction and extending in the X direction at the same height (position) in the Z direction, and a U-shaped passive portion 21b connecting the ends of the two active layers 21a on the opposite sides of the X direction. The passive portion 21b is a passive waveguide with a high mesa structure and is optically connected to the active layer 21a, which is a buried waveguide, via a butt-joint connection. Each protrusion 11D has two ends 21a1 and 21a2 of the waveguide, and light L input to one end 21a1 is optically amplified through one active layer 21a, the passive section 21b, and the other active layer 21a, and is output from the other end 21a2.

[0078] The optical semiconductor element 100D of this embodiment also has a configuration similar to that of the optical semiconductor element 100A of the first embodiment. Therefore, this embodiment also provides the same effects as those of the first embodiment. Furthermore, since the optical semiconductor element 100D of this embodiment includes a U-shaped waveguide including the passive portion 21b, it becomes easier to appropriately set the gain length of the active layer 21a separately from the length of the optical semiconductor element 100D, which also provides the effect of increasing the degree of freedom in designing the optical semiconductor element 100D.

[0079] While the embodiments of the present invention have been described above, they are merely examples and are not intended to limit the scope of the invention. The above embodiments can be implemented in various other forms, and various omissions, substitutions, combinations, and modifications can be made without departing from the spirit of the invention. Furthermore, the specifications of each configuration, shape, and the like (structure, type, direction, model, size, length, width, thickness, height, number, arrangement, position, material, etc.) can be modified as appropriate.

[0080] For example, the optical semiconductor element can also be applied to a laser light emitting element such as a DFB type semiconductor laser. [Explanation of symbols]

[0081] 10...Substrate 10a...side 10b...side 11,11D…Protrusion (first protrusion) 11c...end face 11d...end face 12,12V,12H…Protruding part (second protruding part, positioning part) 12a...end 13...Recess (first recess) 14...Recess (second recess) 20a...first layer (semiconductor layer, first semiconductor layer) 20a1…Part (first part) 20a2...part (second part) 20a3…part (third part) 20b...Second layer (semiconductor layer) 20c...Third layer (semiconductor layer, second semiconductor layer) 20d...Fourth layer (semiconductor layer) 20e...Current blocking layer (semiconductor layer) 20f...current blocking layer (semiconductor layer) 20g: Cladding layer (semiconductor layer) 20h...insulating layer 20i...Protrusions (etching residue) 20j...fifth layer (semiconductor layer) 20m...insulation layer 21...Mesa (First Mesa) 21a…active layer 21a1, 21a2...end 21b... Passive part 22...Mesa (Second Mesa) 31...Electrode (first electrode) 32...Electrode 100, 100A to 100D...Optical semiconductor elements 200...Optical functional element (different parts) 201...base 201a…face 202...Protrusion 202a...End (contact part) 203...Body 203a...Core 203a1...end 203b...end face 300...Optical integrated element h...distance L…Light X…direction (third direction) Y…direction (second direction) Z…direction (first direction)

Claims

1. An optical semiconductor element, a substrate extending across the first direction; a first protruding portion protruding from the substrate in the first direction and having a semiconductor layer including an active layer; a second protruding portion that protrudes from the substrate in the first direction at a position spaced apart from the first protruding portion in a second direction intersecting the first direction, has a semiconductor layer, and functions as a positioning portion used for positioning with an optical functional element; Equipped with a first semiconductor layer formed across a first portion that is rearward of the first protruding portion in the first direction, a second portion that is rearward of the second protruding portion in the first direction, and a third portion that is between the first portion and the second portion, the first semiconductor layer being either not etched by a predetermined etchant that can etch other semiconductor layers or having an etching rate whose ratio to the etching rate of the other semiconductor layers is sufficiently small; a protruding height of the second protruding portion in the first direction from a first recess between the first protruding portion and the second protruding portion is smaller than a protruding height of the first protruding portion in the first direction from the first recess, the optical functional element includes a base, a third protruding portion protruding from the base in a direction opposite to the first direction, and a body provided with an optical waveguide including a core, the optical waveguide being positioned offset from the third protruding portion in a direction intersecting the first direction; The optical semiconductor element is positioned with the optical functional element in a state in which an end of the second protrusion in the first direction and an end of the third protrusion in the opposite direction to the first direction are abutted against each other.

2. The optical semiconductor element according to claim 1 , wherein the active layer and the first semiconductor layer are spaced apart in the first direction by a distance that allows them to be optically isolated from each other.

3. 3. The optical semiconductor element according to claim 1, wherein the second protrusion includes, at a position spaced apart from the first semiconductor layer in the first direction, a second semiconductor layer that is not etched by a predetermined etching solution or etching gas capable of etching another semiconductor layer, or whose ratio of etching rate to the etching rate of the other semiconductor layer is sufficiently small.

4. The optical semiconductor element according to claim 3 , wherein the second semiconductor layer has the same components as the active layer and is aligned with the active layer in the second direction.

5. the first protruding portion includes a first mesa on which a plurality of semiconductor layers including the active layer are stacked, 5. The optical semiconductor element according to claim 1, wherein the second protruding portion includes a second mesa having at least a portion of the same layered structure as the first mesa.

6. The first protrusion includes a first mesa in which a plurality of semiconductor layers including the active layer are stacked, and a stack portion of semiconductor layers provided so as to surround the first mesa on the side opposite to the substrate, The optical semiconductor element according to claim 5 , wherein the second protruding portion at least partially includes a second mesa having the same layered structure as the first mesa, and does not include any semiconductor layer other than the second mesa.

7. The optical semiconductor element according to claim 5 , further comprising a waveguide that includes the active layer and has a curved shape when viewed in a direction along the first direction.

8. The optical semiconductor element according to claim 7 , wherein the waveguide has a U-shaped bent shape when viewed in the first direction.

9. 9. The optical semiconductor element according to claim 1, wherein the second protrusion comprises a plurality of second protrusions.

10. The optical semiconductor element according to claim 9 , wherein the first protrusion is located between the plurality of second protrusions.

11. 11. The optical semiconductor element according to claim 1, wherein the second protrusion is used for positioning the optical functional element in the first direction.

12. 12. The optical semiconductor element according to claim 1, wherein the second protrusion is used for positioning the optical functional element in a direction intersecting the first direction.

13. 13. The optical semiconductor element according to claim 1, wherein the first protrusion comprises a plurality of first protrusions.

14. The optical semiconductor element according to claim 13 , wherein the second protrusion is located between the plurality of first protrusions.

15. 15. The optical semiconductor element according to claim 13, wherein a second recess is provided between the plurality of first protrusions, the second recess having approximately the same depth as a first recess between the first protrusion and the second protrusion.

16. An optical semiconductor element, a substrate extending across the first direction; a first protruding portion protruding from the substrate in the first direction and having a semiconductor layer including an active layer; a second protruding portion that protrudes from the substrate in the first direction at a position spaced apart from the first protruding portion in a second direction intersecting the first direction, has a semiconductor layer, and functions as a positioning portion used for positioning a component other than the optical semiconductor element; Equipped with a first semiconductor layer formed across a first portion that is rearward of the first protruding portion in the first direction, a second portion that is rearward of the second protruding portion in the first direction, and a third portion that is between the first portion and the second portion, the first semiconductor layer being either not etched by a predetermined etchant that can etch other semiconductor layers or having an etching rate whose ratio to the etching rate of the other semiconductor layers is sufficiently small; the first protruding portion includes a first mesa in which a plurality of semiconductor layers including the active layer are stacked, and a stacked portion of semiconductor layers provided so as to surround the first mesa on the side opposite to the substrate, The second protruding portion at least partially includes a second mesa having the same layered structure as the first mesa, and does not include any semiconductor layer other than the second mesa.

17. an optical functional element having an optical waveguide including a core; An optical semiconductor element according to any one of claims 1 to 16; An optical integrated device comprising: the optical functional element has a contact portion that is located on the opposite side of the second protrusion from the substrate and is in contact with the second protrusion, The integrated optical element, wherein the core and the active layer face a third direction intersecting the first direction.

18. A method for manufacturing an optical semiconductor element according to any one of claims 1 to 16, comprising: a step of forming a stacked structure in which a plurality of semiconductor layers are stacked in a first direction on the substrate, the plurality of semiconductor layers including a first semiconductor layer that is not etched by a predetermined etching solution or etching gas that can etch other semiconductor layers, or that has a sufficiently small ratio of an etching rate to an etching rate of the other semiconductor layers; a step of partially removing the laminated structure on a side opposite to the substrate to form a plurality of mesas protruding from the substrate at a plurality of locations spaced apart in a second direction intersecting the first direction; forming a plurality of semiconductor layers so as to fill spaces between the plurality of mesas; forming the first protruding portion and the second protruding portion by etching using the etching solution or the etching gas with the first semiconductor layer as an etching stop layer; A method for manufacturing an optical semiconductor element, comprising:

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