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 an optical function element in a lamination direction of semiconductor layers of 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 that protrudes from the substrate in a first direction, and has a first mesa having a layered structure in which a plurality of semiconductor layers have been layered on the substrate in the first direction and an active layer is included as a semiconductor layer; and a second protruding part that protrudes from the substrate in the first direction at a position separated from the first protruding part in a second direction intersecting the first direction, has the same layered structure as the first mesa, and has one of the plurality of semiconductor layers exposed at the end part thereof in the first direction.SELECTED DRAWING: Figure 1

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 semiconductor elements such as semiconductor laser elements and semiconductor optical amplifiers have been known (for example, Patent Document 1). Also, conventionally, optical integrated elements have been known that integrally include an optical semiconductor element such as that in Patent Document 1 and a portion having a waveguide (hereinafter, this portion will be referred to as an optical functional element) (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 024997 [Patent Document 2] Japanese Patent Application Publication No. 2017-092262 Summary of the Invention [Problem to be solved by the invention]

[0004] In this type of optical integrated element, if the alignment precision between the optical semiconductor element and the optical functional element in the stacking direction of the semiconductor layers of the optical semiconductor element is low, the optical coupling efficiency between the optical semiconductor element and the optical functional element will decrease.

[0005] The optical semiconductor element of Patent Document 1 has a protrusion as a positioning portion with respect to the optical functional element in the stacking direction, and a passivation film is provided on the tip of the protrusion.

[0006] However, the passivation film is prone to variations in thickness and peeling, which may make it difficult to ensure the alignment accuracy between the optical semiconductor element and the optical functional element, and ultimately the optical coupling efficiency between the optical semiconductor element and the optical functional element.

[0007] In the optical integrated element of Patent Document 2, a convex portion provided on an optical functional element is housed in a concave portion provided on an optical semiconductor element, and the concave portion and the convex portion are aligned in the stacking direction.

[0008] However, in a structure in which a protrusion is housed in a recess, the recess must be made relatively large to house the protrusion, which may result in the optical semiconductor element and therefore the optical integrated element becoming larger.

[0009] 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 makes it possible to more easily or more reliably ensure the alignment accuracy between the optical semiconductor element and the optical functional element in the stacking direction of the semiconductor layers of the optical semiconductor element, and also makes it possible to reduce the size. [Means for solving the problem]

[0010] The optical semiconductor element of the present invention includes, for example, a substrate, a first mesa having a layered structure in which a plurality of semiconductor layers are layered in a first direction on the substrate, the first mesa including an active layer as the semiconductor layer, a first protrusion protruding from the substrate in the first direction, and a second protrusion protruding from the substrate in the first direction at a position spaced apart from the first protrusion in a second direction intersecting the first direction, having the same layered structure as the first mesa, and one of the plurality of semiconductor layers exposed at an end in the first direction.

[0011] The optical semiconductor element may include a plurality of second protrusions as the second protrusion.

[0012] In the optical semiconductor element, the first protrusion may be located between the plurality of second protrusions.

[0013] In the optical semiconductor element, the first mesa may include, as the semiconductor layer, a first semiconductor layer that is located on the opposite side of the substrate from the active 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, and the second protrusion may include, as the semiconductor layer, a second semiconductor layer that is made of the same material as the first semiconductor layer, that is exposed at an end in the first direction, and that is aligned with the first semiconductor layer in the second direction.

[0014] In the optical semiconductor element, the first semiconductor layer may be a diffraction grating layer.

[0015] In the optical semiconductor element, the second protrusion may include, as the semiconductor layer, a second semiconductor layer that is exposed at an end in the first direction, is made of the same material as the active layer, and is aligned with the active layer in the second direction.

[0016] The optical integrated element of the present invention comprises, for example, an optical functional element having an optical waveguide including a core, and the above-mentioned optical semiconductor element, wherein 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, and the core and the active layer face a third direction that intersects with the first direction.

[0017] In the optical integrated element, the optical functional element may have a base, and the contact portion may be provided on a third protrusion protruding from the base in a direction opposite to the first direction.

[0018] In the optical integrated element, the optical semiconductor element may have a first electrode spaced apart in the first direction from the active layer, and the optical functional element may have a second electrode provided on the base, and the first electrode and the second electrode may be electrically connected.

[0019] The method for manufacturing an optical semiconductor element of the present invention includes, for example, a step of forming a laminated structure in which a plurality of semiconductor layers are laminated on a substrate in a first direction, the plurality of semiconductor layers including a third semiconductor layer made of a material that functions as an active layer, and an etching stop layer that is not etched by a predetermined etching solution or etching gas that can etch other semiconductor layers or has an etching rate ratio that is sufficiently small relative to the etching rate of the other semiconductor layers, the etching stop layer being the third semiconductor layer or a fourth semiconductor layer on the opposite side of the substrate from the third semiconductor layer; and a step of partially removing the laminated structure on the opposite side of the substrate to separate the third semiconductor layer in a second direction intersecting the first direction. forming a current blocking layer so as to fill spaces between the mesas; forming a conductor layer on the opposite side of the third semiconductor layer from the substrate; forming a first protruding portion including a first mesa that is one of the mesas, a portion of the current blocking layer adjacent to the first mesa, and a portion of the conductor layer on the opposite side of the first mesa from the substrate; and etching a second mesa of the multiple mesas that is different from the first mesa using the specified etching solution or etching gas to form a second protruding portion in which the etching stop layer included in the second mesa is exposed at an end in the first direction. [Effects of the Invention]

[0020] 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]

[0021] [Figure 1] FIG. 1 is an illustrative schematic cross-sectional view of an optical semiconductor element according to the first embodiment. [Figure 2] FIG. 2 is an exemplary schematic plan view of the optical semiconductor element according to the first embodiment. [Figure 3] FIG. 3 is an exemplary schematic cross-sectional view of the integrated optical device according to the first embodiment. [Figure 4] FIG. 4 is an exemplary schematic side view of the optical integrated device according to 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. [Figure 6] FIG. 6 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 7] FIG. 7 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 8] FIG. 8 is an exemplary schematic plan view of a product during the manufacturing process of the optical semiconductor element of the first embodiment, at the same stage as FIG. [Figure 9] FIG. 9 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 FIGS. [Figure 10] FIG. 10 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 11] FIG. 11 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 12] FIG. 12 is an illustrative schematic cross-sectional view of the optical semiconductor element according to the second embodiment. [Figure 13] FIG. 13 is an illustrative schematic cross-sectional view of the optical semiconductor element according to the third embodiment. [Figure 14] FIG. 14 is an illustrative schematic plan view of the optical semiconductor element according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] 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.

[0023] 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.

[0024] In this specification, ordinal numbers are given for convenience to distinguish directions, parts, etc., and do not indicate priority or order.

[0025] 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.

[0026] Furthermore, each figure is a schematic diagram for the purpose of explanation, and the vertical and horizontal scales and ratios of each figure do not necessarily match those of the actual product.

[0027] (First embodiment) (Structure of optical semiconductor element) 1 is a cross-sectional view of an optical semiconductor element 100 according to a first embodiment. As shown in FIG. 1, the optical semiconductor element 100 includes a substrate 10, a first protrusion 11, and two second protrusions 12.

[0028] The substrate 10 has a substantially constant thickness in the Z direction and extends in a direction intersecting the Z direction. 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.

[0029] The first protrusion 11 protrudes in the Z direction from the surface 10a of the substrate 10. Furthermore, the two second protrusions 12 each protrude in the Z direction from the surface 10a. One of the two second protrusions 12 is spaced apart from the first protrusion 11 in the Y direction, and the other of the two second protrusions 12 is spaced apart from the first protrusion 11 in the opposite direction of the Y direction. That is, the first protrusion 11 is located between the two second protrusions 12. The Z direction is an example of a first direction, and the Y direction is an example of a second direction. Note that in this embodiment, the number of second protrusions 12 is two, but the number of second protrusions 12 may be one or three or more. Furthermore, when the number of second protrusions 12 is three or more, the first protrusion 11 may be located between the three or more second protrusions 12.

[0030] The first protrusion 11 is a portion that functions as, for example, a known laser light-emitting element and may also be referred to as a functional portion. The second protrusion 12 is a portion used for aligning the optical semiconductor element 100 and the optical functional element 200 (see FIGS. 3 and 4) in the Z direction and may also be referred to as an alignment portion. The Z-direction end 12a of the second protrusion 12 becomes the contact portion with the optical functional element 200. The end 12a of the second protrusion 12 faces the Z direction and is a plane that intersects with the Z direction. The end 12a may also be referred to as an end face or a contact surface.

[0031] FIG. 2 is a plan view of the optical semiconductor element 100. As shown in FIG. 2, both the first protrusion 11 and the second protrusion 12 extend in the X direction on the substrate 10. FIG. 1 is a cross-sectional view of the optical semiconductor element 100 taken at position II in FIG. 2. The first protrusion 11 and the second protrusion 12 each have the cross-sectional shape shown in FIG. 1, a width in the Y direction, and a height in the Z direction, and extend in the X direction. The first protrusion 11 extends between an end face 11c of the optical semiconductor element 100 facing in the X direction and an end face 11d facing the opposite side of the X direction. The second protrusions 12 each extend a predetermined length from approximately the center of the optical semiconductor element 100 in the X direction. The length of the second protrusions 12 in the X direction is approximately half the length of the optical semiconductor element 100 and the first protrusions 11 in the X direction, but is not limited to this. However, the length of second protrusion 12 in the X direction is preferably at least one-third of the length of optical semiconductor element 100 and first protrusion 11 in the X direction.

[0032] 1, the first protruding portion 11 includes a mesa 21, and the second 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.

[0033] The mesas 21 and 22 are fabricated using the same semiconductor process. Therefore, the mesas 21 and 22 include multiple identical stacked semiconductor layers (first layer 20a to sixth layer 20f) and have partially identical stacked structures. That is, the identical semiconductor layers included in the mesas 21 and 22 are made of the same material, are aligned in the Y direction, and are positioned in 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 not included in the mesa 22 (layer 20d2 farthest from the substrate 10). Specifically, the mesas 21 and 22 include a first layer 20a, a second layer 20b, a third layer 20c, a fourth layer 20d, a fifth layer 20e, a layer 20d1, and a sixth layer 20f, which are stacked in the Z direction from the surface 10a of the substrate 10. The mesa 21 further includes a layer 20d2 on the sixth layer 20f, that is, on the opposite side of the substrate 10 from the sixth layer 20f.

[0034] The first layer 20a has a stacked structure including, for example, n-InP and n-InGaAsP, and functions as a buffer layer in the mesa 21. The second layer 20b is made of n-InP, and functions as a cladding layer in the mesa 21. In the mesa 21, the first layer 20a and the second layer 20b may be collectively referred to as a cladding layer.

[0035] The third layer 20c has a laminated structure containing, for example, n-InGaAsP, and in the mesa 21, acts as the active layer 11a.

[0036] The fourth layer 20d is made of, for example, p-InP. The fifth layer 20e has, for example, first portions made of p-InGaAsP and arranged at a predetermined interval in the X direction, and second portions made of p-InP that fill the spaces between adjacent first portions in the X direction. In the mesa 21, the fifth layer 20e functions as the diffraction grating layer 11b. A layer 20d1 made of the same material as the fourth layer 20d is provided on the opposite side of the substrate 10 from the fifth layer 20e. The fifth layer 20e is sandwiched between the fourth layer 20d and the layer 20d1.

[0037] The sixth layer 20f is made of, for example, p-InGaAsP. The sixth layer 20f is a so-called quaternary layer, and is either not etched by a predetermined etching solution (e.g., hydrochloric acid) or etching gas (e.g., a methane-hydrogen mixed 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 sixth layer 20f to the etching rate of other semiconductor layers is sufficiently small (e.g., 1 / 10 or less). The sixth layer 20f may also be referred to as an etching stop layer.

[0038] In the mesa 21, the sixth layer 20f is located on the opposite side of the substrate 10 from the third layer 20c that functions as the active layer 11a.

[0039] The mesa 22 constitutes the second protrusion 12. The sixth layer 20f is exposed at the end of the mesa 22, i.e., the second protrusion 12, in the Z direction, and constitutes the end 12a. As is clear from FIG. 1 , no other layer, such as a passivation film, is formed on the sixth layer 20f of the second protrusion 12. In this embodiment, the sixth layer 20f of the mesa 21 is an example of a first semiconductor layer, and the sixth layer 20f of the mesa 22 is an example of a second semiconductor layer.

[0040] In the mesa 21, a layer 20d2 made of the same material as the fourth layer 20d is provided on the opposite side of the substrate 10 from the sixth layer 20f.

[0041] In the first protruding portion 11, the mesa 21 is surrounded by adjacent current blocking layers 20g and 20h in the Y direction and the opposite direction to the Y direction, and by adjacent cladding layer 20i in the Z direction. The current blocking layer 20g is made of, for example, p-InP, and the current blocking layer 20h is made of, for example, n-InP. The cladding layer 20i is made of, for example, p-InP.

[0042] A contact layer 20j is stacked on the opposite side of the substrate 10 from the cladding layer 20i. The contact layer 20j is made of, for example, p-InGaAsP. An electrode 31 is provided on the contact layer 20j. The electrode 31 is a p-side electrode and is spaced apart from the active layer 11a in the Z direction. The electrode 31 includes, for example, a base layer 31a, a barrier layer 31b, and a thick film layer 31c stacked in the Z direction from the contact layer 20j. The base layer 31a has a stacked structure containing, for example, Au and AuZn, the barrier layer 31b contains, for example, Pt, and the thick film layer 31c contains, for example, Au. The electrode 31 is an example of a first electrode.

[0043] The side surfaces of the first protrusion 11 in the Y direction and the opposite side to the Y direction are covered with an insulating film 20n. The insulating film 20n is made of, for example, SiN.

[0044] 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.

[0045] (Structure of optical functional elements and optical integrated elements) 3 is a cross-sectional view of an optical integrated device 300 including the optical semiconductor device 100 of the present embodiment shown in FIGS. 1 and 2 and an optical functional device 200. 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. FIG. 3 shows a state in which the optical semiconductor device 100 and the optical functional device 200 are aligned.

[0046] The optical functional element 200 includes a base 201, a protrusion 202, and an electrode 204. The base 201 has a substantially constant thickness in the Z direction and extends in a direction intersecting the Z direction. The base 201 has a surface 201a. The surface 201a faces in the opposite direction to the Z direction and intersects with the Z direction.

[0047] The protrusion 202 protrudes from the surface 201a in the opposite direction to the Z direction. The protrusion 202 is arranged to be aligned in the Z direction with the second protrusion 12 of the optical semiconductor element 100 and to be in contact with it in the Z direction. In this embodiment, the optical functional element 200 has two protrusions 202 corresponding to the second protrusions 12, respectively. The length in the X direction and the width in the Y direction of the protrusion 202 are set corresponding to the second protrusion 12. Note that in this embodiment, the length in the X direction of the protrusion 202 is longer than the length in the X direction of the second protrusion 12, and the width in the Y direction of the protrusion 202 is wider than the width in the Y direction of the second protrusion 12, but this is not limited to this.

[0048] The optical semiconductor element 100 and the optical functional element 200 are aligned in the Z direction by contacting the end 12a of the second protrusion 12 of the optical semiconductor element 100 in the Z direction with the end 202a of the protrusion 202 of the optical functional element 200 in the opposite Z direction. In the aligned state, the end 202a is located on the opposite side of the substrate 10 with respect to the second protrusion 12 of the optical semiconductor element 100, and is in contact with the end 12a of the second protrusion 12. The end 202a is an example of a contact portion, and the protrusion 202 is an example of a third protrusion.

[0049] The electrode 204 is provided on the surface 201a and faces the electrode 31 of the optical semiconductor element 100 with a gap (not shown) in the Z direction. The electrode 31 and the electrode 204 are electrically connected via a joint 50, such as an AuSn solder bump. In this embodiment, the optical functional element 200 includes a base 201 and a protruding portion 202 protruding from the base 201 in the opposite direction of the Z direction. This allows a portion between the base 201 and the first protruding portion 11 of the optical semiconductor element 100 where the electrode 31 and the electrode 204 are electrically connected via the joint 50. This configuration reduces the distance between the electrode 31 and the electrode 204, thereby reducing the electrical resistance between the electrode 31 and the electrode 204. The electrode 204 is an example of a second electrode.

[0050] FIG. 4 is a side view of a portion of an optical integrated device 300 including the optical semiconductor device 100 of this embodiment shown in FIGS.

[0051] As shown in FIG. 4, the optical functional element 200 has a body 203. 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. 4, an end face 203b of the body 203 facing away from the X direction faces an end face 11c of the optical semiconductor element 100 in the X direction, and the active layer 11a and the core 203a face the X direction and are aligned in the X direction. Laser light output from the active layer 11a at the end face 11c is coupled to the core 203a and transmitted within the core 203a. The X direction is an example of a third direction.

[0052] In such a configuration, if the active layer 11a and the core 203a are misaligned in the Z direction, the optical coupling efficiency between the active layer 11a and the core 203a will decrease. In this regard, in this embodiment, for example, by matching the distance δ1 between the center of the active layer 11a in the Z direction and the end 12a of the second protrusion 12 and the distance δ2 between the center of the core 203a in the Z direction and the end 202a of the protrusion 202 on the opposite side in the Z direction, the active layer 11a and the core 203a can be aligned in the Z direction.

[0053] As described above, in this embodiment, the mesa 21 included in the first protrusion 11 and the mesa 22 included in the second protrusion 12 have the same stacked structure in which multiple semiconductor layers are stacked. Therefore, as shown in FIG. 1 , the distance δ1 can be set more easily and accurately as the Z-direction distance δ1 between the Z-direction center of the third layer 20c, which functions as the active layer 11a in the mesa 21, and the Z-direction end 12a of the sixth layer 20f, which serves as the end 12a in the mesa 22 (second protrusion 12), by controlling the layer thickness of each semiconductor layer in the manufacturing process (crystal growth process) of the mesas 21 and 22. Furthermore, as described above, according to this embodiment, the end 12a of the second protrusion 12 is not covered with another layer such as a passivation film, and therefore the alignment accuracy in the Z direction is not reduced due to variations in the thickness or peeling of the other layer. Therefore, according to this embodiment, compared to the conventional configuration, the optical semiconductor element 100 and the optical functional element 200 can be aligned more easily and accurately in the Z direction, i.e., the stacking direction of the semiconductor layers in the optical semiconductor element 100, thereby achieving the effect of suppressing a decrease in optical coupling efficiency.

[0054] In this embodiment, the optical semiconductor element 100 includes a plurality of second protrusions 12. Furthermore, the first protrusion 11 is located between the plurality of second protrusions 12. This configuration has the effect of enabling the optical semiconductor element 100 to be supported more stably by the plurality of second protrusions 12.

[0055] (Method of manufacturing an optical semiconductor element) Figures 5 to 11 are diagrams showing products during each manufacturing step in the manufacturing method of the optical semiconductor element 100. Figures 5 to 7 and 9 to 11 are cross-sectional views of the products, and Figure 8 is a plan view of the product at the same stage as Figure 7. The products may also be referred to as laminated structures.

[0056] First, as shown in FIG. 5, a first layer 20a, a second layer 20b, a third layer 20c, a fourth layer 20d, a layer 20e1 that will form the first portion of the diffraction grating layer 11b, and a layer 20d1 formed on the diffraction grating layer 11b are deposited by crystal growth on a wafer-like substrate 10. The layer 20e1 is made of p-InGaAsP. The third layer 20c, which functions as the active layer 11a in the mesa 21, is an example of a third semiconductor layer.

[0057] 5, layers 20e1 and 20d1 are selectively removed by etching at intervals in the X direction. The removed portions are then filled with p-InP, thereby forming fifth layer 20e, which functions as diffraction grating layer 11b in mesa 21, and layer 20d1 on fifth layer 20e.

[0058] Next, as shown in Fig. 7, a sixth layer 20f, a layer 20d2, a sacrificial layer 20k, and a mask layer 20m are formed on the layer 20d1 formed on the fifth layer 20e. The sacrificial layer 20k is made of, for example, InGaAsP, and the mask layer 20m is made of, for example, SiN. The mask layer 20m formed in Fig. 7 is shaped to have, for example, the planar shape shown in Fig. 8.

[0059] 9, in the product of FIG. 7, portions not covered by mask layer 20m are removed by etching, and recesses C and mesas 21 and 22 are formed on the opposite side of mask layer 20m and sacrificial layer 20k in the Z direction. That is, by partially removing the product of FIG. 7 on the side opposite to substrate 10, multiple mesas 21 and 22 protruding above substrate 10 and recesses C between the multiple mesas 21 and 22 are formed. During this etching, sacrificial layer 20k serves to adjust the side shapes of mesas 21 and 22 to be gently curved along the Z direction.

[0060] Next, as shown in FIG. 10, current blocking layers 20g and 20h are formed so as to fill the recess C (see FIG. 9) between the mesas 21 and 22.

[0061] 11, the mask layer 20m and the sacrificial layer 20k are removed from the product of FIG. 10, and the cladding layer 20i, the contact layer 20j, the base layer 31a, the barrier layer 31b, and the thick film layer 31c are laminated on the opposite side of the product from the substrate 10. The contact layer 20j, the base layer 31a, the barrier layer 31b, and the thick film layer 31c are examples of conductor layers.

[0062] 11, the portion between mesa 21 and mesa 22 on the side opposite to substrate 10 is removed by etching using a predetermined etching solution or etching gas, thereby forming first protrusion 11 (without insulating film 20n) containing mesa 21 and second protrusion 12 as mesa 22, as shown in FIG. 1. First protrusion 11 includes mesa 21, portions of current blocking layers 20g and 20h, cladding layer 20i, and contact layer 20j adjacent to mesa 21 (peripheral portions of mesa 21 that cover mesa 21), and electrode 31.

[0063] During this etching, the sixth layer 20f functions as an etching stop layer in the mesa 22 (second protrusion 12), and the sixth layer 20f is exposed at the Z-direction end 12a of the second protrusion 12. In this embodiment, the sixth layer 20f is an example of the fourth semiconductor layer.

[0064] Thereafter, the end face of the substrate 10 opposite to the Z direction is polished to form a face 10b, and then the electrode 32 is formed on the face 10b by, for example, evaporation lift-off. Next, ohmic contact is made between the semiconductor layers of the electrode 31, the electrode 32, and the first protrusion 11 by, for example, heat treatment at about 400°C. In addition, the side surface of the first protrusion 11 is covered with an insulating film 20n.

[0065] 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 (see FIG. 2) in the X direction, and a high-reflection coating is applied to the end face 11d in the opposite X direction, thereby completing the optical semiconductor element 100 shown in FIGS. 1 and 2.

[0066] As described above, the structure and method of this embodiment enable the optical semiconductor element 100 and the optical functional element 200 to be aligned more easily and with greater precision in the Z direction, i.e., in the stacking direction of the semiconductor layers in the optical semiconductor element 100, and as a result, it is possible to more easily and reliably suppress a decrease in the optical coupling efficiency between the optical semiconductor element 100 and the optical functional element 200. In other words, this embodiment provides an improved and novel optical semiconductor element 100, an optical integrated element 300, and a method for manufacturing the optical semiconductor element 100.

[0067] Furthermore, in the optical integrated element 300 of this embodiment, the height in the Z direction of the second protrusion 12 is lower than the height in the Z direction of the first protrusion 11, and the end 12a of the second protrusion 12 of the optical semiconductor element 100 and the end 202a of the protrusion 202 of the optical functional element 200 come into 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 a recess in the other, the other would need a peripheral wall to form a recess to accommodate the protrusion provided on the other. The protrusion and the peripheral wall would overlap in a direction intersecting the protrusion direction (stacking direction) at the aligned portion, potentially increasing 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 second protrusion 12 and the protrusion 202 come into contact with each other, can be configured more compactly than a configuration in which the protrusion and the recess are aligned.

[0068] (Second embodiment) 12 is a cross-sectional view of an optical semiconductor element 100A according to the second embodiment. Except for the cross-sectional shape, the optical semiconductor element 100A has the same configuration as the optical semiconductor element 100 according to the first embodiment.

[0069] As shown in FIG. 12 , in this embodiment, the fifth layer 20e, which will become the diffraction grating layer 11b in the mesa 21, is exposed at the end 12a of the second protrusion 12. The fifth layer 20e is also a so-called quaternary layer and can function as an etching stop layer that is not etched by a predetermined etching solution or etching gas that etches other semiconductor layers. Therefore, as in this embodiment, the fifth layer 20e, which will become the diffraction grating layer 11b in the mesa 21, can be used as the end 12a of the second protrusion 12. In this embodiment, the fifth layer 20e of the mesa 21 is an example of a first semiconductor layer, and the fifth layer 20e of the mesa 22 is an example of a second semiconductor layer. In addition, in this embodiment, the fifth layer 20e is an example of a fourth semiconductor layer.

[0070] This embodiment also provides the same effects as the first embodiment. Furthermore, according to this embodiment, in the mesa 22, the distance δ1 from the third layer 20c, which becomes the active layer 11a in the mesa 21, to the end 12a can be set to be shorter. This can further reduce the effect on the distance δ1 caused by variations in the thickness of the semiconductor layer located on the opposite side of the substrate 10 from the third layer 20c, and ultimately may further suppress a decrease in the optical coupling efficiency.

[0071] (Third embodiment) 13 is a cross-sectional view of an optical semiconductor element 100B according to the third embodiment. Except for the cross-sectional shape, the optical semiconductor element 100B has the same configuration as the optical semiconductor element 100 according to the first embodiment.

[0072] 13 , in this embodiment, the third layer 20c, which will become the active layer 11a in the mesa 21, is exposed at the end 12a of the second protrusion 12. The third layer 20c is also a so-called quaternary layer and can function as an etching stop layer that is not etched by a predetermined etching solution or etching gas that etches other semiconductor layers. Therefore, as in this embodiment, the third layer 20c, which will become the active layer 11a in the mesa 21, can be formed as the end 12a of the second protrusion 12.

[0073] This embodiment also provides the same effects as the first embodiment. Furthermore, according to this embodiment, in the mesa 22, the distance δ1 from the third layer 20c, which becomes the active layer 11a in the mesa 21, to the end 12a can be set to be even shorter. This can further reduce the effect on the distance δ1 caused by variations in the thickness of the semiconductor layers located on the opposite side of the substrate 10 from the third layer 20c, and ultimately may further suppress a decrease in the optical coupling efficiency.

[0074] (Fourth embodiment) 14 is a plan view of an optical semiconductor element 100C according to the fourth embodiment. Except for the shape and arrangement of the second protrusions 12, the optical semiconductor element 100C has the same configuration as the optical semiconductor element 100 according to the first embodiment.

[0075] As shown in FIG. 14 , in this embodiment, two second protrusions 12 are provided on both sides of the first protrusion 11 in the Y direction, spaced apart in the X direction. This configuration also achieves the same effects as the first embodiment. Furthermore, this embodiment also achieves the effect of reducing the weight of the optical semiconductor element 100 by making the second protrusions 12 smaller. The optical functional element 200 may be provided with the same number of protrusions 202 as the number of second protrusions 12, respectively, or may be provided with a number of protrusions 202 corresponding to multiple second protrusions 12, but fewer than the number of second protrusions 12. Furthermore, the centers of two second protrusions 12 aligned in the X direction are preferably spaced apart by at least one-third of the length of the optical semiconductor element 100.

[0076] 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. [Explanation of symbols]

[0077] 10...Substrate 10a...side 10b...side 11...First protrusion 11a...Active layer 11b...diffraction grating layer 11c...end face 11d...end face 12...Second protrusion 12a...end 20a...First layer (semiconductor layer) 20b...Second layer (semiconductor layer) 20c...Third layer (semiconductor layer, third semiconductor layer, etching stop layer) 20d...Fourth layer (semiconductor layer) 20d1...layer (semiconductor layer) 20d2...layer (semiconductor layer) 20e...fifth layer (semiconductor layer, first semiconductor layer, fourth semiconductor layer, etching stop layer) 20e1…layer 20f...sixth layer (semiconductor layer, first semiconductor layer, second semiconductor layer, fourth semiconductor layer, etching stop layer) 20g...Current blocking layer (semiconductor layer) 20h...Current blocking layer (semiconductor layer) 20i...cladding layer (semiconductor layer) 20j...contact layer (semiconductor layer) 20k...sacrificial layer 20m...mask layer 20n...insulating film 21...Mesa (First Mesa) 22...Mesa (Second Mesa) 31...Electrode (first electrode) 31a...base layer 31b...Barrier layer 31c...Thick film layer 32...Electrode 50…Joint part 100, 100A~100C...Optical semiconductor element 200...Optical functional element 201...base 201a…face 202...Protruding part (third protruding part) 202a...End (contact part) 203...Body 203a...Core 203b...end face 204...electrode (second electrode) 300...Optical integrated element C...Concave X…direction (third direction) Y…direction (second direction) Z…direction (first direction) δ1...distance δ2...distance

Claims

1. A substrate; a first mesa having a stacked structure in which a plurality of semiconductor layers are stacked in a first direction on the substrate, the first mesa including an active layer as the semiconductor layer, and a first protruding portion protruding from the substrate in the first direction; 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, includes the same stacked structure as the first mesa, and has one of the plurality of semiconductor layers exposed at an end portion in the first direction; Equipped with the first mesa includes, as the semiconductor layer, a first semiconductor layer that is located on the opposite side of the substrate with respect to the active layer, and 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; an optical semiconductor element, wherein the second protrusion portion includes a second semiconductor layer as the semiconductor layer, made of the same material as the first semiconductor layer, exposed at an end in the first direction, and aligned with the first semiconductor layer in the second direction.

2. The optical semiconductor device according to claim 1 , wherein the first semiconductor layer is a diffraction grating layer.

3. A substrate, a first mesa having a stacked structure in which a plurality of semiconductor layers are stacked in a first direction on the substrate, the first mesa including an active layer as the semiconductor layer, and a first protruding portion protruding from the substrate in the first direction; 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, includes the same stacked structure as the first mesa, and has one of the plurality of semiconductor layers exposed at an end portion in the first direction; Equipped with The second protrusion portion includes, as the semiconductor layer, a second semiconductor layer that is exposed at an end in the first direction, is made of the same material as the active layer, and is aligned with the active layer in the second direction.

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

5. The optical semiconductor element according to claim 4 , wherein the first protrusion is located between the plurality of second protrusions.

6. an optical functional element having an optical waveguide including a core; An optical semiconductor element according to any one of claims 1 to 5; 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.

7. The optical functional element has a base, The optical integrated element according to claim 6 , wherein the contact portion is provided on a third protrusion that protrudes from the base in a direction opposite to the first direction.

8. the optical semiconductor element has a first electrode spaced apart from the active layer in the first direction; the optical functional element has a second electrode provided on the base, The integrated optical device according to claim 7 , wherein the first electrode and the second electrode are electrically connected.

9. A process for 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 third semiconductor layer made of a material that functions as an active layer, and an etching stop layer that is not etched by a predetermined etching solution or etching gas that can etch other semiconductor layers or has an etching rate ratio that is sufficiently small relative to the etching rate of the other semiconductor layers, the etching stop layer being either a fourth semiconductor layer on the opposite side of the substrate from the third semiconductor layer or the third semiconductor layer; 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 current blocking layer so as to fill spaces between the mesas; forming a conductor layer on the opposite side of the third semiconductor layer from the substrate; forming a first protruding portion including a first mesa that is one of the plurality of mesas, a portion of the current blocking layer adjacent to the first mesa, and a portion of the conductor layer on the opposite side of the substrate with respect to the first mesa; a step of etching a second mesa, which is different from the first mesa, among the plurality of mesas using the predetermined etching solution or etching gas to form a second protruding portion in which the etching stop layer included in the second mesa is exposed at an end portion in the first direction; A method for manufacturing an optical semiconductor element, comprising:

Images