Semiconductor photodetector

Abstract

To improve an ESD withstand voltage.SOLUTION: A semiconductor light-receiving element includes: a substrate 10; a light-receiving mesa structure 14 disposed on a first surface of the substrate 10 and including a plurality of semiconductor layers that are stacked and include an absorption layer 16; an insulating film 26 overlapping with the light-receiving mesa structure 14 in a lateral direction orthogonal to a stacking direction of the plurality of semiconductor layers and surrounding a side surface of the light-receiving mesa structure 14; a first electrode 30 disposed on the first surface of the substrate 10, including a mesa electrode 32 electrically connected in contact with an upper surface of an uppermost layer 20 of the plurality of semiconductor layers, including a protruding electrode 38 that extends outward in conduction with the mesa electrode 32, overlaps with the light-receiving mesa structure 14 in the lateral direction, and is disposed on the insulating film 26, the protruding electrode 38 being narrower than the mesa electrode 32 in a width that is orthogonal to the extending direction; and a second electrode 40 disposed on the first surface of the substrate 10 and electrically connected to a lower surface of a lowermost layer 18 of the plurality of semiconductor layers.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a semiconductor light receiving element.

Background Art

[0002] In optical communication, the transmission speed is increasing, and high-speed responsiveness of an optical module is required. In an optical module having a function of converting an optical signal into an electric signal, high-speed responsiveness of a built-in semiconductor light receiving element is required. The semiconductor light receiving element is configured to apply a voltage to a plurality of stacked semiconductor layers (Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The response speed of a semiconductor light receiving element is improved by reducing the capacitance, but this leads to a decrease in the withstand voltage against electrostatic discharge (ESD).

[0005] An object of the present invention is to improve the ESD withstand voltage.

Means for Solving the Problems

[0006] The semiconductor photodetector includes a substrate, a plurality of semiconductor layers arranged on a first surface of the substrate and stacked, the plurality of semiconductor layers comprising a photodetector mesa structure including an absorption layer, an insulating film overlapping the photodetector mesa structure in a transverse direction perpendicular to the stacking direction of the plurality of semiconductor layers and surrounding the side surface of the photodetector mesa structure, a mesa electrode arranged on the first surface of the substrate and in contact with and electrically connected to the upper surface of the uppermost layer of the plurality of semiconductor layers, a protruding electrode conductive to the mesa electrode and extending outward, overlapping the photodetector mesa structure in the transverse direction and located on the insulating film, the protruding electrode comprising a first electrode narrower than the mesa electrode in width perpendicular to the extension direction, and a second electrode arranged on the first surface of the substrate and electrically connected to the lower surface of the lowermost layer of the plurality of semiconductor layers. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic plan view of a semiconductor photodetector according to the first embodiment. [Figure 2] Figure 1 shows a cross-sectional view of a semiconductor photodetector along line II-II. [Figure 3] Figure 1 is a cross-sectional view of a semiconductor photodetector shown by line III-III. [Figure 4] This is a cross-sectional view of a semiconductor photodetector according to Modified Example 1. [Figure 5] This is a schematic plan view of a semiconductor photodetector according to modified example 2. [Figure 6] This is a schematic plan view of a semiconductor photodetector according to modified example 3. [Figure 7] This is a schematic plan view of a semiconductor photodetector according to Modification 4. [Figure 8] This is a schematic plan view of a semiconductor photodetector according to the second embodiment. [Figure 9] Figure 8 is a cross-sectional view of the semiconductor photodetector along the line IX-IX. [Figure 10] This is a schematic plan view of a semiconductor photodetector according to the third embodiment. [Figure 11] Figure 10 is a cross-sectional view of the semiconductor photodetector along the line XI-XI. [Figure 12]It is a cross-sectional view taken along line XII-XII of the semiconductor light-receiving element shown in FIG. 10. [Figure 13] It is a schematic plan view of the semiconductor light-receiving element according to the fourth embodiment. [Figure 14] It is a cross-sectional view taken along line XIV-XIV of the semiconductor light-receiving element shown in FIG. 13. [Figure 15] It is a cross-sectional view taken along line XV-XV of the semiconductor light-receiving element shown in FIG. 13. [Figure 16] It is a schematic plan view of the semiconductor light-receiving element according to the fifth embodiment. [Figure 17] It is a cross-sectional view taken along line XVII-XVII of the semiconductor light-receiving element shown in FIG. 16. [Figure 18] It is a schematic plan view of the semiconductor light-receiving element according to the sixth embodiment. [Figure 19] It is a cross-sectional view taken along line XIX-XIX of the semiconductor light-receiving element shown in FIG. 18.

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be specifically and detailedly described with reference to the drawings. In all the figures, members denoted by the same reference numerals have the same or equivalent functions, and repeated descriptions thereof will be omitted. Note that the sizes of the figures do not necessarily match the magnification.

[0009] [First Embodiment] FIG. 1 is a schematic plan view of the semiconductor light-receiving element according to the first embodiment. FIG. 2 is a cross-sectional view taken along line II-II of the semiconductor light-receiving element shown in FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III of the semiconductor light-receiving element shown in FIG. 1. The semiconductor light-receiving element has a substrate 10. The substrate 10 is a semi-insulating substrate and is made of, for example, InP doped with Fe. A contact layer 12 is provided on the substrate 10. The contact layer 12 is a semiconductor layer of the first conductivity type (for example, n-type).

[0010] [Light-Receiving Mesa Structure] The semiconductor light-receiving element has a light-receiving mesa structure 14. The light-receiving mesa structure 14 is disposed on the first surface of the substrate 10 (specifically, on the contact layer 12). The light-receiving mesa structure 14 is in contact with the contact layer 12 and is electrically connected. The semiconductor light-receiving element is a surface-incident type semiconductor light-receiving element in which light enters from the upper surface of the light-receiving mesa structure 14. For example, it is a PIN-type light-receiving element having a structure in which an intrinsic semiconductor layer is inserted between a p-type semiconductor layer and an n-type semiconductor layer. The semiconductor light-receiving element may be an avalanche photodiode (APD).

[0011] The light-receiving mesa structure 14 includes a plurality of stacked semiconductor layers. The plurality of semiconductor layers includes an absorption layer 16. The light incident on the light-receiving mesa structure 14 enters the absorption layer 16, is absorbed, and is converted into electricity. The absorption layer 16 may be either an intrinsic semiconductor layer or a semiconductor layer of a conductivity type, or a combination of both. The absorption layer 16 is sandwiched between the lowermost layer 18 and the uppermost layer 20 of the plurality of semiconductor layers. The lowermost layer 18 is on the contact layer 12 and has a first conductivity type. The uppermost layer 20 is on the absorption layer 16 and has a second conductivity type. For example, the lowermost layer 18 is an n-type buffer layer, and the uppermost layer 20 is a p-type contact layer. A p-type buffer layer may be provided between the absorption layer sixteen and the uppermost layer 20. Note that the p-type and n-type may be reversed.

[0012] Above the substrate 10, a first spacer 22 is provided. The first spacer 22 is composed of a plurality of layers and has a mesa structure similar to the light-receiving mesa structure 14 except that the lowermost layer is the same layer as the contact layer 12. Above the substrate 10, a second spacer 24 is provided. The second spacer 24 has the same layer structure as the first spacer 22. The light-receiving mesa structure 14, the first spacer 22, and the second spacer twenty-four can be formed by growing the above-described layer structure using an MBE (Molecular Beam Epitaxy) apparatus and then separating each using lithography technology.

[0013] [Insulating film] The semiconductor photodetector has an insulating film 26. The insulating film 26 covers and protects the photodetector mesa structure 14, the first spacer 22, the second spacer 24, and the exposed surface (e.g., the entire surface) of the substrate 10. The insulating film 26 is a passivation film. The insulating film 26 overlaps the photodetector mesa structure 14 in a transverse direction perpendicular to the stacking direction of the multiple semiconductor layers. The insulating film 26 surrounds the sides of the photodetector mesa structure 14. The insulating film 26 extends outward from the photodetector mesa structure 14 (bottom layer 18).

[0014] The insulating film 26 covers the upper surface of the top layer 20 of the multiple semiconductor layers. The insulating film 26 is formed to function as a low-reflectivity film depending on the wavelength of light that the semiconductor photodetector can receive (850 nm band to 1.55 μm band). Light that enters the photodetector mesa structure 14 passes through the insulating film 26. The insulating film 26 has an opening 28 (through hole) on its upper surface. The opening 28 is a ring-shaped slit. Part of the insulating film 26 is inside the opening 28 (the region surrounded by the slit). The insulating film 26 also has an opening 28 on the contact layer 12.

[0015] [1st electrode] The semiconductor photodetector has a first electrode 30. The first electrode 30 is located on the first surface of the substrate 10. Multiple parts of the first electrode 30 will be described below, but these are integral parts.

[0016] [Mesa electrode] The first electrode 30 includes a mesa electrode 32. The mesa electrode 32 is in contact (physically and electrically connected) with the upper surface of the uppermost layer 20 of the multiple semiconductor layers. The portion of the first electrode 30 that overlaps with the opening 28 of the insulating film 26 is the mesa electrode 32. The mesa electrode 32 has a ring-shaped planar form, but it may also be a C-shape with a part that is not connected, or its outer shape may be elliptical, oblong, or a combination of straight lines and arcs. The first electrode 30 does not have a portion that rests on the insulating film 26 inside the opening 28 (slit) of the insulating film 26.

[0017] [External electrode] The first electrode 30 includes an external electrode 34 (e.g., a pad). The external electrode 34 is positioned to cover the upper surface of the first spacer 22 and is bonded to a wire (not shown) to provide an electrical connection with an external device (e.g., a transimpedance amplifier). The external electrode 34 includes a larger portion than the mesa electrode 32. The external electrode 34 is located on an insulating film 26.

[0018] [Connecting wire] The first electrode 30 includes a connecting wire 36 that connects the external electrode 34 and the mesa electrode 32. The connecting wire 36 is narrower than the external electrode 34 and narrower than the mesa electrode 32 in terms of its width in the direction of extension.

[0019] [Protruding electrode] The first electrode 30 includes a projection electrode 38. The projection electrode 38 is conductive to the mesa electrode 32 and extends outward. The projection electrode 38 overlaps the photoreceiving mesa structure 14 in the lateral direction and lies on the insulating film 26. The projection electrode 38 extends outward from the photoreceiving mesa structure 14 along the insulating film 26, with its tip above the contact layer 12. The projection electrode 38 and the connecting wire 36 extend in opposite directions to each other.

[0020] The projection electrode 38 is narrower than the mesa electrode 32 in width perpendicular to the extension direction. The projection electrode 38 is uniform in width in all parts along the extension direction. The width of the projection electrode 38 is preferably 1 / 4 or less of the width (e.g., diameter) of the mesa electrode 32. If the width is too wide, the capacitance increases and hinders fast response.

[0021] The protruding electrode 38 is electrically connected to the external electrode 34 via the mesa electrode 32 and connecting wire 36. The protruding electrode 38 is electrically connected to the external electrode 34 in a direction different from the direction of extension from the mesa electrode 32. The end of the protruding electrode 38 in the direction of extension is not connected to any other electrode.

[0022] [Second electrode] The semiconductor photodetector has a second electrode 40. The second electrode 40 is located on the first surface of the substrate 10. The first electrode 30 is located between a pair of portions (e.g., pads) of the second electrode 40. A projection electrode 38 extends toward a portion of the second electrode 40. The second electrode 40 contacts the contact layer 12 inside the opening of the insulating film 26. The second electrode 40 is electrically connected to the underside of the bottom layer 18 of the plurality of semiconductor layers.

[0023] The second electrode 40 consists of a region positioned on the upper surface of the second spacer 24, a region shaped like an arc along the outer circumference of the light-receiving mesa structure 14, and a region connecting these two regions. By applying a voltage between the first electrode 30 and the second electrode 40, the light (optical signal) that enters the light-receiving mesa structure 14 is absorbed, and an electrical signal is obtained.

[0024] [Evaluation Test] One of the evaluation tests for semiconductor photodetectors is the ESD withstand voltage test. The ESD withstand voltage test is a test to determine at what voltage the semiconductor photodetector will be destroyed. Alternatively, it is a test to confirm that the semiconductor photodetector will not be destroyed when the required ESD withstand voltage is applied.

[0025] Generally, ESD withstand voltage and capacitance are proportional. In other words, semiconductor photodetectors with high capacitance also have high ESD withstand voltage. However, semiconductor photodetectors with high capacitance have difficulty handling high-speed responses.

[0026] As a comparative example, we assumed a case where the first electrode does not have a protruding electrode, and the photodetector mesa structure is designed to support 50 Gbps operation. When an ESD withstand voltage test was performed, the required specifications could not be met. Analysis of the semiconductor photodetector after voltage application revealed that a portion of the semiconductor layer contained in the photodetector mesa structure was destroyed.

[0027] On the other hand, when an ESD withstand voltage test was performed on the semiconductor photodetector according to the first embodiment, the ESD withstand voltage was more than 1.5 times that of the comparative example, satisfying the required specifications. It is presumed that the ESD withstand voltage improved because the addition of the protruding electrode 38 dispersed the charge concentration within the semiconductor layer. It was found that the effect of improving the ESD withstand voltage was greater when the protruding electrode 38 was positioned far from the connecting line 36, for example, at a position directly opposite the connection point between the connecting line 36 and the mesa electrode 32.

[0028] If the sole purpose were to improve ESD withstand voltage, it would be preferable to arrange the protruding electrodes 38 to cover the entire photoreceiving mesa structure 14 rather than placing them only on a small part of the structure. However, this would increase the capacitance, which is undesirable from the viewpoint of high-speed response. In this embodiment, since the width of the protruding electrodes 38 is narrow, it is possible to achieve both improved ESD withstand voltage and maintenance of high-speed response.

[0029] [Example 1] Figure 4 is a cross-sectional view of a semiconductor photodetector according to Modification 1. In Modification 1, the protruding electrode 38A does not extend outward from the photodetector mesa structure 14A. The protruding electrode 38A is positioned partway along the side of the photodetector mesa structure 14A. Therefore, parasitic capacitance caused by the protruding electrode 38A can be reduced. The structure of Modification 1 is the same as that of the first embodiment, except for the shape of the protruding electrode 38A.

[0030] [Differentiation 2] Figure 5 is a schematic plan view of a semiconductor photodetector according to Modification 2. In Modification 2, the projection electrode 38B is narrower in width towards the tip in the extension direction. The projection electrode 38B is triangular in shape, not rectangular. This structure allows for a larger area of ​​the projection electrode 38B compared to the first embodiment, thereby further improving the ESD withstand voltage. The structure of Modification 2 is the same as that of the first embodiment, except for the shape of the projection electrode 38B.

[0031] [Difference 3] Figure 6 is a schematic plan view of a semiconductor photodetector according to Modification 3. In Modification 3, the protruding electrodes 38C are each of a pair of protruding electrodes 38C. With this structure, the ESD withstand voltage can be further improved compared to the first embodiment because there are more protruding electrodes 38C. The structure of Modification 3 is the same as that of the first embodiment, except that there is a pair of protruding electrodes 38C.

[0032] [Differentiation Example 4] Figure 7 is a schematic plan view of a semiconductor photodetector according to Modification 4. In Modification 4, the protruding electrode 38D is each of a plurality of protruding electrodes 38D. One of the plurality of protruding electrodes 38D is on the opposite side from the connecting line 36D. With this structure, compared to the first embodiment, the ESD withstand voltage can be further improved because there are more protruding electrodes 38D. However, the parasitic capacitance also increases, so four or fewer protruding electrodes 38D are preferable. In short, the shape and number of protruding electrodes 38D should be determined according to the required ESD withstand voltage specifications and high-speed response characteristics. The structure of Modification 4 is the same as the first embodiment except that there are multiple protruding electrodes 38D.

[0033] [Second Embodiment] Figure 8 is a schematic plan view of a semiconductor photodetector according to the second embodiment. Figure 9 is a cross-sectional view of the semiconductor photodetector shown in Figure 8 along the line IX-IX.

[0034] The first electrode 230 includes a first layer 242 and a second layer 244 made of separate components, which are partially stacked and electrically conductive. The first layer 242 and the second layer 244 may be made of the same material or different materials. For example, the first layer 242 may have a Ti / Pt / Au stacked structure from the bottom up, and the second layer 244 may have a Ti / Au stacked structure from the bottom up.

[0035] A portion of the first layer 242 consists of an external electrode 234 and a first connecting wire 236A drawn from the external electrode 234. A portion of the second layer 244 consists of a second connecting wire 236B that partially overlaps and conducts with the first connecting wire 236A. The first connecting wire 236A and the second connecting wire 236B constitute the connecting wire 236.

[0036] The first layer 242 includes a mesa contact portion 246 located inside the opening 228 of the insulating film 226 and in contact with the light-receiving mesa structure 214. The mesa contact portion 246 is ring-shaped. The second layer 244 includes a first laminated portion 248 overlapping a part of the mesa contact portion 246 and a second laminated portion 250 overlapping another part of the mesa contact portion 246. The mesa contact portion 246, the first laminated portion 248, and the second laminated portion 250 constitute the mesa electrode 232. The second laminated portion 250 is continuous and integrated with the second connecting line 236B. The second layer 244 includes a protruding electrode 238 that is continuous and integrated with the first laminated portion 248. At least a part of the mesa electrode 232 and at least a part of the protruding electrode 238 are separate components.

[0037] A pair of second electrodes 240 are separated. The ends of the pair of second electrodes 240 are located in a pair of regions flanking the photodetector mesa structure 214. There are no second electrodes 240 at the end of the direction in which the protruding electrode 238 extends. The effects described in the first embodiment can be obtained in this configuration as well. Other configurations of the semiconductor photodetector described in the first embodiment are applicable here.

[0038] [Third Embodiment] Figure 10 is a schematic plan view of a semiconductor photodetector according to the third embodiment. Figure 11 is a cross-sectional view of the semiconductor photodetector shown in Figure 10 along the line XI-XI. Figure 12 is a cross-sectional view of the semiconductor photodetector shown in Figure 10 along the line XII-XII.

[0039] Unlike the first embodiment, the insulating film 326 does not exist inside the outer shape of the aperture 328. In other words, there is no insulating film surrounded by the mesa electrode 332. On the upper surface of the light-receiving mesa structure 314, the mesa electrode 332 is in the center, so light does not pass through. The semiconductor photodetector is a back-side incident semiconductor photodetector.

[0040] The substrate 310 is made of a light-transmitting material and has a lens portion 352 (focusing lens) on the second surface (back surface) opposite to the first surface, which overlaps with the light-receiving mesa structure 314. The lens portion 352 is designed to focus incoming light onto the light-receiving mesa structure 314 (particularly the absorption layer 316), thereby improving the light-receiving efficiency. The effects described in the first embodiment can also be obtained with this configuration. Other configurations of the semiconductor photodetector described in the first or second embodiment are applicable here.

[0041] [Fourth Embodiment] Figure 13 is a schematic plan view of a semiconductor photodetector according to the fourth embodiment. Figure 14 is a cross-sectional view of the semiconductor photodetector shown in Figure 13 along the line XIV-XIV. Figure 15 is a cross-sectional view of the semiconductor photodetector shown in Figure 13 along the line XV-XV.

[0042] The semiconductor photodetector further has an embedding layer 454 that embeds the photodetector mesa structure 414 in the lateral direction. The embedding layer 454 is a semi-insulating semiconductor layer. The embedding layer 454 is arranged to cover the sides of the photodetector mesa structure 414 (multiple semiconductor layers). film It surrounds the embedded layer 454.

[0043] In this embodiment, the distance between the photodetector mesa structure 414 (e.g., the bottom layer 418 of the multiple semiconductor layers) and the protruding electrode 438 can be increased, and parasitic capacitance caused by the protruding electrode 438 can be reduced compared to the first embodiment. Other configurations of the semiconductor photodetector described in the first to third embodiments are applicable hereto.

[0044] [Fifth Embodiment] Figure 16 is a schematic plan view of a semiconductor photodetector according to the fifth embodiment. Figure 17 is a cross-sectional view of the semiconductor photodetector shown in Figure 16, taken along line XVII-XVII. The semiconductor photodetector is a back-side incident semiconductor photodetector, and the substrate 510 has a lens portion 552 on its second surface (back side). The photodetector mesa structure 514 can be modified according to the first embodiment.

[0045] The external electrode 534 rests on the insulating film 526 inside the opening 528 (the region surrounded by the slit). The external electrode 534 is surrounded by the mesa electrode 532. The insulating film 526 is interposed between the uppermost layer 520 of the multiple semiconductor layers and the external electrode 534. The semiconductor photodetector does not have a first spacer. The first electrode 530 does not have a connecting line.

[0046] A second spacer 524 is provided. The second spacer 524 has a rectangular shape in planar form. The second spacer 524 is composed of the same multiple semiconductor layers as the light-receiving mesa structure 514. The second electrode 540 covers the entire second spacer 524 and is in contact with the substrate 510 for electrical connection. The substrate 510 is a light-transmitting conductive substrate and may be made of InP.

[0047] The semiconductor photodetector is used mounted on a submount (not shown). Specifically, the semiconductor photodetector is mounted with the photodetector mesa structure 514 facing the mounting surface of the submount (junction-down mounting). The first electrode 530 and the second electrode 540 are joined to wiring provided on the mounting surface of the submount. Solder can be used for joining. The wiring of the submount is mainly connected to the external electrode 534. A portion of the protruding electrode 538 also contacts the wiring of the submount. However, the tip of the protruding electrode 538 in the extension direction is not connected to other electrodes. The first to fourth modifications of the protruding electrode 538 can be applied. In this embodiment as well, the ESD withstand voltage can be improved by having the protruding electrode 538. Other configurations of the semiconductor photodetector described in the first or second embodiment can be applied here.

[0048] [Sixth Embodiment] Figure 18 is a schematic plan view of a semiconductor photodetector according to the sixth embodiment. Figure 19 is a cross-sectional view of the semiconductor photodetector shown in Figure 18, taken along the line XIX-XIX.

[0049] This embodiment differs from the fifth embodiment in that the mesa electrode 632 also serves as an external electrode. In other words, the insulating film 626 does not have a portion inside the opening 628. Therefore, the first electrode 630 does not have a portion that rests on the insulating film 626 inside the opening 628. Consequently, since insulation is not laminated on the mesa electrode 632 (external electrode) in the region where light entering from the second surface of the substrate 610 is reflected, light reflection can be suppressed.

[0050] [Summary of the Embodiment] (1) The semiconductor photodetector according to the present invention comprises a substrate 10, a photodetector mesa structure 14 arranged on the first surface of the substrate 10 and comprising a plurality of stacked semiconductor layers, the plurality of semiconductor layers comprising an absorption layer 16, an insulating film 26 that overlaps the photodetector mesa structure 14 in a transverse direction perpendicular to the stacking direction of the plurality of semiconductor layers and surrounds the side surface of the photodetector mesa structure 14, a mesa electrode 32 arranged on the first surface of the substrate 10 and electrically connected to the upper surface of the uppermost layer 20 of the plurality of semiconductor layers, a protruding electrode 38 that is conductive to the mesa electrode 32 and extends outward, overlapping the photodetector mesa structure 14 in a transverse direction and located on the insulating film 26, the protruding electrode 38 comprising a first electrode 30 that is narrower than the mesa electrode 32 in width perpendicular to the extension direction, and a second electrode 40 arranged on the first surface of the substrate 10 and electrically connected to the lower surface of the lowermost layer 18 of the plurality of semiconductor layers. The presence of the protruding electrode 38 can improve the ESD withstand voltage.

[0051] (2) A semiconductor photodetector as described in (1), wherein the insulating film 26 extends outward from the photodetector mesa structure 14.

[0052] (3)(2) A semiconductor photodetector as described in (2), wherein the protruding electrode 38 is a semiconductor photodetector that extends outward from the photodetector mesa structure 14 along the insulating film 26.

[0053] (4)(2) A semiconductor photodetector described in (2), wherein the protruding electrode 38A does not extend outward from the photodetector mesa structure 14A.

[0054] (5) A semiconductor photodetector as described in any one of items (1) to (4), wherein the protruding electrode 38 is uniform in width in any portion along the extension direction.

[0055] (6) A semiconductor photodetector described in any one of items (1) to (4), wherein the protruding electrode 38B is narrower in width towards the tip in the extension direction.

[0056] (7) A semiconductor photodetector described in any one of items (1) to (6), wherein the protruding electrode 38C is each of a plurality of protruding electrodes 38C.

[0057] (8) A semiconductor photodetector as described in any one of (1) to (7), wherein the insulating film 26 covers the upper surface of the uppermost layer 20 of a plurality of semiconductor layers and has an opening 28 on the upper surface, and the portion of the first electrode 30 that overlaps the opening 28 is a mesa electrode 32.

[0058] A semiconductor photodetector as described in (9)(8), wherein the mesa electrode 632 also serves as an external electrode.

[0059] A semiconductor photodetector as described in (10)(8), wherein the aperture 28 is a ring-shaped slit, a portion of the insulating film 26 is inside the aperture 28, and the mesa electrode 32 has a ring-shaped planar shape.

[0060] A semiconductor photodetector as described in (11)(10), wherein the first electrode 30 has no portion that rests on the insulating film 26 inside the aperture 28.

[0061] A semiconductor photodetector as described in (12), (10), or (11), wherein the first electrode 530 has an external electrode 534 that rests on the insulating film 526 inside the aperture 528.

[0062] (13) A semiconductor photodetector as described in any one of paragraphs (1) to (11), wherein the first electrode 30 includes an external electrode 34 electrically connected to the mesa electrode 32, and the external electrode 34 includes a portion wider than the mesa electrode 32.

[0063] A semiconductor photodetector as described in (14)(13), wherein the first electrode 30 includes a connecting line 36 connecting an external electrode 34 and a mesa electrode 32, and the connecting line 36 and the protruding electrode 38 are semiconductor photodetectors extending in opposite directions to each other.

[0064] A semiconductor photodetector as described in (15), (13), or (14), wherein the external electrode 34 is a semiconductor photodetector located on an insulating film 26.

[0065] A semiconductor photodetector described in any one of paragraphs (1)(1) to (15), wherein at least a portion of the mesa electrode 232 and at least a portion of the projection electrode 238 are separate components.

[0066] A semiconductor photodetector as described in any one of paragraphs (1) to (16), wherein the second electrode 40 includes a pair of parts, and the first electrode 30 is located between the pair of parts.

[0067] A semiconductor photodetector as described in any one of paragraphs (18)(1) to (17), further comprising an embedding layer 454 that embeds a photodetector mesa structure 414 in the lateral direction, and an insulating layer film This is a semiconductor photodetector surrounding the embedded layer 454.

[0068] A semiconductor photodetector described in any one of paragraphs (1)(1) to (18), wherein the protruding electrode 38 extends toward a part of the second electrode 40.

[0069] A semiconductor photodetector as described in any one of paragraphs (20)(1) to (19), wherein the substrate 310 is made of a light-transmitting material and has a lens portion 352 on a second surface opposite to the first surface that overlaps with a light-receiving mesa structure 314.

[0070] The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the configurations described in the embodiments can be replaced with substantially the same configuration, a configuration that produces the same effect, or a configuration that can achieve the same purpose. [Explanation of Symbols]

[0071] 10 Substrate, 12 Contact layer, 14 Photodetector mesa structure, 14A Photodetector mesa structure, 16 Absorption layer, 18 Bottom layer, 20 Top layer, 22 First spacer, 24 Second spacer, 26 Insulating film, 28 Aperture, 30 First electrode, 32 Mesa electrode, 34 External electrode, 36 Connecting line, 36D Connecting line, 38 Protruding electrode, 38A Protruding electrode, 38B Protruding electrode, 38C Protruding electrode, 38D Protruding electrode, 40 Second electrode, 214 Photodetector mesa structure, 226 Insulating film, 228 Aperture, 230 First electrode, 232 Mesa electrode, 234 External electrode, 236 Connecting line, 236A First connecting line, 236B Second connecting line, 238 Protruding electrode, 240 Second electrode, 242 First layer, 244 Second layer, 246 Mesa contact section, 248 First laminated section, 250 Second laminated section, 310 Substrate, 314 Photodetecting mesa structure, 316 Absorption layer, 326 Insulating film, 328 Aperture, 332 Mesa electrode, 352 Lens section, 414 Photodetecting mesa structure, 418 Bottom layer, 438 Protruding electrode, 454 Embedding layer, 510 Substrate, 514 Photodetecting mesa structure, 520 Top layer, 524 Second spacer, 526 Insulating film, 528 Aperture, 530 First electrode, 532 Mesa electrode, 534 External electrode, 538 Protruding electrode, 540 Second electrode, 552 Lens section, 610 Substrate, 626 Insulating film, 628 Aperture, 630 First electrode, 632 Mesa electrode.

Claims

1. circuit board and Located on the first surface side of the substrate, the substrate includes a plurality of stacked semiconductor layers, the plurality of semiconductor layers including an absorption layer and a photodetecting mesa structure, An insulating film that overlaps the light-receiving mesa structure in a transverse direction perpendicular to the stacking direction of the plurality of semiconductor layers and surrounds the side surface of the light-receiving mesa structure, The substrate includes a mesa electrode located on the first surface side, which contacts and electrically connects to the upper surface of the uppermost layer of the plurality of semiconductor layers, and includes a protruding electrode that is conductive to the mesa electrode, extends outward, overlaps the light-receiving mesa structure in the lateral direction, and lies on the insulating film, wherein the protruding electrode has a first electrode that is narrower than the mesa electrode in width perpendicular to the extension direction, A second electrode located on the first surface side of the substrate and electrically connected to the lower surface of the lowest layer of the plurality of semiconductor layers, It has, The semiconductor photodetector has an open end at which the projection electrode extends from the mesa electrode in the aforementioned direction, with no electrical connection.

2. A semiconductor photodetector according to claim 1, The insulating film is a semiconductor photodetector that extends outward from the photodetector mesa structure.

3. A semiconductor photodetector according to claim 2, The protruding electrode is a semiconductor photodetector that extends outward from the photodetector mesa structure along the insulating film.

4. A substrate and Located on the first surface side of the substrate, the substrate includes a plurality of stacked semiconductor layers, the plurality of semiconductor layers including an absorption layer and a photodetecting mesa structure, An insulating film that overlaps the light-receiving mesa structure in a transverse direction perpendicular to the stacking direction of the plurality of semiconductor layers and surrounds the side surface of the light-receiving mesa structure, The substrate includes a mesa electrode located on the first surface side, which contacts and electrically connects to the upper surface of the uppermost layer of the plurality of semiconductor layers, and includes a protruding electrode that is conductive to the mesa electrode, extends outward, overlaps the light-receiving mesa structure in the lateral direction, and lies on the insulating film, wherein the protruding electrode has a first electrode that is narrower than the mesa electrode in width perpendicular to the extension direction, A second electrode located on the first surface side of the substrate and electrically connected to the lower surface of the lowest layer of the plurality of semiconductor layers, It has, The insulating film extends outward from the light-receiving mesa structure, The aforementioned protruding electrode is a semiconductor photodetector that does not extend outward from the photodetector mesa structure.

5. A semiconductor photodetector according to claim 1, The aforementioned protruding electrode is a semiconductor photodetector in which the width is uniform in any portion along the extension direction.

6. A semiconductor photodetector according to claim 1, The aforementioned protruding electrode is a semiconductor photodetector whose width becomes narrower towards the tip in the extension direction.

7. A semiconductor photodetector according to claim 1, The aforementioned protruding electrode is a semiconductor photodetector, which is each of a plurality of protruding electrodes.

8. A semiconductor photodetector according to claim 1, The insulating film covers the upper surface of the uppermost layer of the plurality of semiconductor layers and has an opening on the upper surface. A semiconductor photodetector in which the portion of the first electrode that overlaps with the aperture is the mesa electrode.

9. A semiconductor photodetector according to claim 8, The insulating film does not have an inner portion of the opening. The first electrode does not have a portion that rests on the insulating film inside the opening. A semiconductor photodetector in which the insulating film is not laminated on the mesa electrode.

10. A semiconductor photodetector according to claim 8, The aforementioned opening is a ring-shaped slit, A portion of the insulating film is located inside the opening. The mesa electrode is a semiconductor photodetector having a ring-shaped planar form.

11. A semiconductor photodetector according to claim 10, The first electrode is a semiconductor photodetector that does not have a portion that rests on the insulating film inside the opening.

12. A semiconductor photodetector according to claim 10, The first electrode is a semiconductor photodetector having a portion that rests on the insulating film inside the opening.

13. A semiconductor photodetector according to claim 1, The first electrode includes a portion that is electrically connected to the mesa electrode, The portion electrically connected to the mesa electrode is a semiconductor photodetector that includes a portion wider than the mesa electrode.

14. A substrate and Located on the first surface side of the substrate, the substrate includes a plurality of stacked semiconductor layers, the plurality of semiconductor layers including an absorption layer and a photodetecting mesa structure, An insulating film that overlaps the light-receiving mesa structure in a transverse direction perpendicular to the stacking direction of the plurality of semiconductor layers and surrounds the side surface of the light-receiving mesa structure, The substrate includes a mesa electrode located on the first surface side, which contacts and electrically connects to the upper surface of the uppermost layer of the plurality of semiconductor layers, and includes a protruding electrode that is conductive to the mesa electrode, extends outward, overlaps the light-receiving mesa structure in the lateral direction, and lies on the insulating film, wherein the protruding electrode has a first electrode that is narrower than the mesa electrode in width perpendicular to the extension direction, A second electrode located on the first surface side of the substrate and electrically connected to the lower surface of the lowest layer of the plurality of semiconductor layers, It has, The first electrode includes a portion that is electrically connected to the mesa electrode, The portion electrically connected to the mesa electrode includes a portion wider than the mesa electrode, The first electrode includes the portion that is electrically connected to the mesa electrode and a connecting wire that connects the mesa electrode, The connecting wire and the protruding electrode are semiconductor photodetectors extending from the mesa electrode in opposite directions.

15. A semiconductor photodetector according to claim 13, The portion electrically connected to the mesa electrode is a semiconductor photodetector located on the insulating film.

16. A semiconductor photodetector according to claim 1, At least a portion of the mesa electrode and at least a portion of the protruding electrode are separate semiconductor photodetectors.

17. A semiconductor photodetector according to claim 1, The second electrode includes a pair of parts, The first electrode is a semiconductor photodetector located between the pair of portions.

18. A semiconductor photodetector according to claim 1, The present invention further comprises an embedding layer that embeds the light-receiving mesa structure in the lateral direction, The insulating film is a semiconductor photodetector surrounding the embedding layer.

19. A semiconductor photodetector according to claim 1, The aforementioned protruding electrode is a semiconductor photodetector that extends toward a part of the second electrode.

20. A semiconductor photodetector according to claim 1, The substrate is made of a light-transmitting material and has a semiconductor photodetector element on a second surface opposite to the first surface, which has a lens portion that overlaps with the light-receiving mesa structure.

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