Method for manufacturing a light-receiving element and a light-receiving element

Abstract

To provide a manufacturing method of a light-receiving element that can reduce a leakage current, and a light-receiving element.SOLUTION: A manufacturing method of a light-receiving element has: a process of forming a first contact layer on one face of a substrate; a process of forming a light-receiving layer on the first contact layer; a process of forming a second contact layer on the light-receiving layer; a process of removing a part of the second contact layer, the light-receiving layer and the first contact layer, and forming a first groove where the first contact layer is exposed; a process of embedding resin into the first groove; and a process of removing the second contact layer after the process of embedding resin, and forming a second groove separating pixels.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to a method for manufacturing a photodetector and to a photodetector. [Background technology]

[0002] A two-dimensional array type photodetector is known in which pixels separated by grooves are arranged in two dimensions (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-47639 [Overview of the project] [Problems that the invention aims to solve]

[0004] In conventional photodetectors, damage to the mesa interface of the pixel area remains after deposition of the SiN or SiO2 film used as an etching mask to form the mesa of the electrode extraction area, resulting in increased leakage current.

[0005] This disclosure aims to provide a method for manufacturing a photodetector and a photodetector that can reduce leakage current. [Means for solving the problem]

[0006] The method for manufacturing a light-receiving element according to the present disclosure includes the steps of: forming a first contact layer on one surface of a substrate; forming a light-receiving layer on the first contact layer; forming a second contact layer on the light-receiving layer; removing the second contact layer, the light-receiving layer, and a portion of the first contact layer to form a first groove in which the first contact layer is exposed; filling the first groove with resin; and, after the step of filling with resin, removing the second contact layer to form a second groove for separating pixels. [Effects of the Invention]

[0007] According to the present disclosure, the leakage current can be reduced.

Brief Description of the Drawings

[0008] [Figure 1] FIG. 1 is a cross-sectional view showing a light receiving element according to an embodiment. [Figure 2] FIG. 2 is a top view showing a light receiving element according to an embodiment. [Figure 3] FIG. 3 is a cross-sectional view (Part 1) showing a method for manufacturing a light receiving element according to an embodiment. [Figure 4] FIG. 4 is a cross-sectional view (Part 2) showing a method for manufacturing a light receiving element according to an embodiment. [Figure 5] FIG. 5 is a cross-sectional view (Part 3) showing a method for manufacturing a light receiving element according to an embodiment. [Figure 6] FIG. 6 is a cross-sectional view (Part 4) showing a method for manufacturing a light receiving element according to an embodiment. [Figure 7] FIG. 7 is a cross-sectional view (Part 5) showing a method for manufacturing a light receiving element according to an embodiment. [Figure 8] FIG. 8 is a cross-sectional view (Part 6) showing a method for manufacturing a light receiving element according to an embodiment. [Figure 9] FIG. 9 is a cross-sectional view (Part 7) showing a method for manufacturing a light receiving element according to an embodiment. [Figure 10] FIG. 10 is a cross-sectional view (Part 8) showing a method for manufacturing a light receiving element according to an embodiment. [Figure 11] FIG. 11 is a cross-sectional view (Part 9) showing a method for manufacturing a light receiving element according to an embodiment. [Figure 12] FIG. 12 is a cross-sectional view (Part 10) showing a method for manufacturing a light receiving element according to an embodiment. [Figure 13] FIG. 13 is a cross-sectional view (Part 11) showing a method for manufacturing a light receiving element according to an embodiment. [Figure 14] FIG. 14 is a cross-sectional view (Part 12) showing a method for manufacturing a light receiving element according to an embodiment. [Figure 15]FIG. 15 is a cross-sectional view (No. 13) showing a method for manufacturing a light-receiving element according to an embodiment. [Figure 16] FIG. 16 is a cross-sectional view (No. 14) showing a method for manufacturing a light-receiving element according to an embodiment. [Figure 17] FIG. 17 is a cross-sectional view (No. 15) showing a method for manufacturing a light-receiving element according to an embodiment. [Figure 18] FIG. 18 is a cross-sectional view (No. 16) showing a method for manufacturing a light-receiving element according to an embodiment. [Figure 19] FIG. 19 is a cross-sectional view (No. 17) showing a method for manufacturing a light-receiving element according to an embodiment. [Figure 20] FIG. 20 is a cross-sectional view (No. 18) showing a method for manufacturing a light-receiving element according to an embodiment. [Figure 21] FIG. 21 is a cross-sectional view (No. 19) showing a method for manufacturing a light-receiving element according to an embodiment. [Figure 22] FIG. 22 is a cross-sectional view (No. 20) showing a method for manufacturing a light-receiving element according to an embodiment. [Figure 23] FIG. 23 is a cross-sectional view (No. 21) showing a method for manufacturing a light-receiving element according to an embodiment. [Figure 24] FIG. 24 is a cross-sectional view (No. 22) showing a method for manufacturing a light-receiving element according to an embodiment. [Figure 25] FIG. 25 is a cross-sectional view (No. 23) showing a method for manufacturing a light-receiving element according to an embodiment. [Figure 26] FIG. 26 is a cross-sectional view (No. 24) showing a method for manufacturing a light-receiving element according to an embodiment. [Figure 27] FIG. 27 is a cross-sectional view (No. 25) showing a method for manufacturing a light-receiving element according to an embodiment. [Figure 28] FIG. 28 is a cross-sectional view (No. 26) showing a method for manufacturing a light-receiving element according to an embodiment. [Figure 29] FIG. 29 is a cross-sectional view (No. 27) showing a method for manufacturing a light-receiving element according to an embodiment. [Figure 30] FIG. 30 is a cross-sectional view (No. 28) showing a method for manufacturing a light-receiving element according to an embodiment. [Modes for carrying out the invention]

[0009] The implementation methods are described below.

[0010] [Description of Embodiments in this Disclosure] The embodiments of this disclosure are first listed and described. In the following description, the same or corresponding elements are denoted by the same reference numerals, and the same description of them is not repeated.

[0011] [1] A method for manufacturing a photodetector according to one aspect of the present disclosure includes the steps of: forming a first contact layer on one side of a substrate; forming a photodetector layer on the first contact layer; forming a second contact layer on the photodetector layer; removing the second contact layer, the photodetector layer, and a part of the first contact layer to form a first groove in which the first contact layer is exposed; filling the first groove with resin; and, after the step of filling the resin, removing the second contact layer to form a second groove for separating pixels. In this case, when forming the SiN film or SiO2 film for the etching mask to form the first groove, the side surface of the mesa forming the pixels is not exposed. Therefore, damage to the side surface of the mesa during the formation of the SiN film or SiO2 film for the etching mask to form the first groove can be reduced. As a result, leakage current can be reduced.

[0012] [2] In [1], a step of forming an insulating film on the resin may be further included between the step of embedding the resin and the step of forming the second groove. In this case, etching of the resin when removing the etching mask used when forming the second groove is easier to suppress.

[0013] [3] In [1] or [2], the step of removing the damaged layer may be further included after the step of forming the second groove. In this case, the damaged layer that occurred when forming the second groove can be removed.

[0014] [4] In [1] to [3], the resin may be a benzocyclobutene resin or a polyimide resin. In this case, the resin is easily embedded in the first groove by coating.

[0015] [5] A photodetector according to another aspect of the present disclosure includes a substrate, a first contact layer provided on one side of the substrate, a light-receiving layer provided on the first contact layer, a second contact layer provided on the light-receiving layer, a first groove from which the second contact layer, the light-receiving layer, and a portion of the first contact layer are removed, exposing the first contact layer, a resin provided in a portion of the interior of the first groove, and a second groove for separating the pixels from which the second contact layer has been removed. In this case, the second groove for pixel separation can be formed after the first groove for electrode extraction. As a result, when a SiN film or SiO2 film for etching masks to form the first groove is deposited, the side surface of the mesa forming the pixels is not exposed. Therefore, damage to the side surface of the mesa when depositing the SiN film or SiO2 film for etching masks to form the first groove can be reduced. As a result, leakage current can be reduced.

[0016] [Details of the embodiments of this disclosure] The embodiments of this disclosure will be described in detail below, but this disclosure is not limited to these embodiments.

[0017] (Photodetector) The light-receiving element 100 according to the embodiment will be described with reference to Figures 1 and 2. Figure 1 is a cross-sectional view showing the light-receiving element 100 according to the embodiment. Figure 2 is a top view showing the light-receiving element 100 according to the embodiment. Figure 1 is a cross-sectional view taken along the line II-II in Figure 2. The light-receiving element 100 is a light-receiving element that detects near-infrared light. The light-receiving element 100 is a so-called back-incident light-receiving element. As shown in Figure 1, the light-receiving element 100 includes a substrate 10.

[0018] The substrate 10 is, for example, an InP substrate. The substrate 10 is doped with Fe (iron) as an impurity element and is semi-insulated. The thickness of the substrate 10 is, for example, 500 μm to 700 μm. The substrate 10 has a rectangular shape, for example, with a side length of 2 mm to 15 mm. The substrate 10 has a first main surface 10a and a second main surface 10b opposite to the first main surface 10a. An n-type contact layer 21, a light-receiving layer 22, a wide-gap layer 23, and a p-type contact layer 24 are provided on the first main surface 10a in this order. An anti-reflective film 80 is provided on the second main surface 10b. The anti-reflective film 80 is formed of, for example, a SiN film.

[0019] The n-type contact layer 21 is provided on the substrate 10. The n-type contact layer 21 is formed of n-InP, and silicon (Si) is present as an impurity element that makes it n-type, with a total content of approximately 2 × 10⁻¹⁶ 18 cm -3 It is doped with the following concentration. The thickness of the n-type contact layer 21 is, for example, 1 μm to 3 μm.

[0020] The light-receiving layer 22 is provided on the n-type contact layer 21. The light-receiving layer 22 is made of in-type material that is not doped with impurity elements. 0.53 Ga 0.47 It is formed of As. The thickness of the light-receiving layer 22 is, for example, 1 μm to 3 μm.

[0021] The wide-gap layer 23 is provided on top of the light-receiving layer 22. The wide-gap layer 23 includes, for example, an n-type wide-gap layer 23a and a p-type wide-gap layer 23b. The n-type wide-gap layer 23a is formed of n-InP, and contains approximately 2 × 10⁻¹⁶ Si as an impurity element to make it n-type. 15 cm -3 It is doped with the following concentration. The thickness of the n-type wide gap layer 23a is, for example, 0.2 μm to 0.8 μm. The p-type wide gap layer 23b is formed of p-InP, and zinc (Zn) is present as an impurity element that makes it p-type, with approximately 2 × 10⁻⁶ particles. 15 cm -3It is doped at the concentration of. The thickness of the p-type wide-gap layer 23b is, for example, 0.1 μm to 0.5 μm. A pn junction is formed at the interface between the n-type wide-gap layer 23a and the p-type wide-gap layer 23b.

[0022] The p-type contact layer 24 is provided on the wide-gap layer 23. The p-type contact layer 24 is formed of p-InGaAs and is doped with Zn as an impurity element for p-type at a concentration of about 1×10 19 cm -3 The thickness of the p-type contact layer 24 is, for example, 0.1 μm to 0.3 μm.

[0023] In the light-receiving element 100, a groove 71 for electrode extraction and a groove 72 for pixel isolation are formed.

[0024] The groove 71 is formed by removing a part of the p-type contact layer 24, the wide-gap layer 23, the light-receiving layer 22, and the n-type contact layer 21. The groove 71 is formed along the outer periphery. At the bottom surface of the groove 71, the n-type contact layer 21 is exposed, and at the side surface, the n-type contact layer 21, the light-receiving layer 22, the n-type wide-gap layer 23a, the p-type wide-gap layer 23b, and the p-type contact layer 24 are exposed. A first passivation film 41 is provided on the exposed n-type contact layer 21 and on the side surfaces of the n-type contact layer 21, the light-receiving layer 22, the n-type wide-gap layer 23a, the p-type wide-gap layer 23b, and the p-type contact layer. The first passivation film 41 is formed of, for example, a SiN film with a thickness of 100 nm to 400 nm. Resin 51 is embedded inside the groove 71. The resin 51 may be, for example, benzocyclobutene (BCB) or polyimide resin. A second passivation film 42 and a third passivation film 43 are provided in this order on the resin 51.

[0025] When viewed from a direction perpendicular to the first main surface 10a, the photodetector 100 is provided with a groove 73 that partially overlaps with the groove 71. The groove 73 is formed by removing the third passivation film 43, the second passivation film 42, the resin 51, and the first passivation film 41. The groove 73 is formed along the outer circumference. In the groove 73, the n-type contact layer 21 is exposed at the bottom, and the first passivation film 41, the resin 51, the second passivation film 42, and the third passivation film 43 are exposed on the sides. N-electrodes 61 are formed on the exposed n-type contact layer 21, on the sides of the first passivation film 41, the resin 51, the second passivation film 42, and the third passivation film 43, and on the third passivation film 43. The n electrode 61 is formed by a multilayer film of, for example, a titanium (Ti) film, a platinum (Pt) film, and a gold (Au) film.

[0026] The groove 72 is formed by removing a portion of the p-type contact layer 24 and the wide gap layer 23. The n-type wide gap layer 23a is exposed at the bottom of the groove 72. Each pixel is formed by the mesa 70 separated by the groove 72. A p-electrode 62 is formed on the p-type contact layer 24 in the mesa 70. The p-electrode 62 is formed of a laminated film of, for example, a Ti film, a Pt film, and an Au film. A third passivation film 43 is provided on the exposed p-type contact layer 24 and on the wide gap layer 23 and the sides of the p-type contact layer 24. The side of the pn junction of the wide gap layer 23 is in contact with the third passivation film 43. The third passivation film 43 is formed of, for example, a SiN film with a thickness of 100 nm to 400 nm.

[0027] As described above, the photodetector 100 according to the embodiment has a structure in which resin 51 is embedded in a part of the inside of the groove 71 for electrode extraction, and resin 51 is not embedded in the groove 72 for pixel separation. In this case, the groove 72 for pixel separation can be formed after the groove 71 for electrode extraction. As a result, when the SiN film or SiO2 film for the etching mask for forming the groove 71 is deposited, the side surface of the mesa 70 that forms the pixels is not exposed. Therefore, damage to the side surface of the mesa 70 when depositing the SiN film or SiO2 film for the etching mask for forming the groove 71 can be reduced. As a result, leakage current can be reduced.

[0028] (Manufacturing method for light-receiving elements) Referring to Figures 3 to 29, a method for manufacturing the light-receiving element 100 according to the embodiment will be described.

[0029] First, as shown in Figure 3, an n-type contact layer 21, a light-receiving layer 22, a wide-gap layer 23, and a p-type contact layer 24 are formed on the first main surface 10a of the substrate 10 in this order by epitaxial growth.

[0030] The substrate 10 is, for example, an InP substrate. The substrate 10 is doped with Fe as an impurity element and is semi-insulated. The thickness of the substrate 10 is, for example, 500 μm to 700 μm.

[0031] The n-type contact layer 21 is formed of n-InP, and the impurity element that makes it n-type is Si, which is approximately 2 × 10⁻⁶ 18 cm -3 It is doped with the following concentration. The thickness of the n-type contact layer 21 is, for example, 1 μm to 3 μm.

[0032] The light-receiving layer 22 is made of In, which is not doped with impurity elements. 0.53 Ga 0.47 It is formed of As. The thickness of the light-receiving layer 22 is, for example, 1 μm to 3 μm.

[0033] The wide gap layer 23 includes, for example, an n-type wide gap layer 23a and a p-type wide gap layer 23b. The n-type wide gap layer 23a is formed of n-InP, and contains approximately 2 × 10⁻¹⁶ Si as an impurity element to form the n-type layer. 15 cm -3 It is doped with the following concentration. The thickness of the n-type wide gap layer 23a is, for example, 0.2 μm to 0.8 μm. The p-type wide gap layer 23b is formed of p-InP, and Zn is present as an impurity element that makes it p-type, with approximately 2 × 10⁻⁶ of Zn. 15 cm -3 It is doped with a concentration of [a certain substance]. The thickness of the p-type wide gap layer 23b is, for example, 0.1 μm to 0.5 μm. A pn ​​junction is formed at the interface between the n-type wide gap layer 23a and the p-type wide gap layer 23b.

[0034] The p-type contact layer 24 is formed of p-InGaAs, and contains approximately 1 × 10⁻¹⁶ Zn as an impurity element that makes it p-type. 19 cm -3 It is doped with the following concentration. The thickness of the p-type contact layer 24 is, for example, 0.1 μm to 0.3 μm.

[0035] Next, grooves 71 for electrode extraction are formed along the outer circumference of the substrate 10. First, as shown in Figure 4, a SiN film 31 is deposited on the p-type contact layer 24 by plasma CVD (chemical vapor deposition). The thickness of the SiN film 31 is, for example, 0.6 μm to 2 μm. An SiO2 film may be used instead of the SiN film 31. After this, a photoresist is applied to the deposited SiN film 31, and a resist pattern 32 is formed by exposure and development using an exposure apparatus. The thickness of the resist pattern 32 is, for example, 1 μm to 4 μm. The resist pattern 32 has openings 32a in the region where the grooves 71 are formed.

[0036] Next, as shown in Figure 5, the SiN film 31 at the openings 32a of the resist pattern 32 is removed by dry etching using a fluorine-based gas, and an etching mask is formed using the SiN film 31. Examples of fluorine-based gases include CF4 gas and SF6 gas.

[0037] Next, as shown in Figure 6, the resist pattern 32 is removed using an organic solvent or the like.

[0038] Next, as shown in Figure 7, a groove 71 is formed by dry etching using a halogen-based gas to remove the p-type contact layer 24, p-type wide gap layer 23b, n-type wide gap layer 23a, light-receiving layer 22, and a portion of the n-type contact layer 21 in the area where the SiN film 31 has been removed. In the groove 71, the n-type contact layer 21 is exposed at the bottom, and the n-type contact layer 21, light-receiving layer 22, n-type wide gap layer 23a, p-type wide gap layer 23b, and p-type contact layer 24 are exposed on the sides. Damage layers, not shown, may occur on the exposed surfaces of the n-type contact layer 21, light-receiving layer 22, n-type wide gap layer 23a, p-type wide gap layer 23b, and p-type contact layer 24 due to dry etching. Examples of halogen-based gases are Cl2 gas and SiCl4 gas.

[0039] Next, as shown in Figure 8, the damaged layer generated during the formation of the groove 71 is removed using a hydrochloric acid-based etching solution. In this case, the damaged layer generated during the formation of the groove 71 can be removed. At this time, the n-type contact layer 21 is left at the bottom surface of the groove 71. The hydrochloric acid-based etching solution is, for example, HCl.

[0040] Next, as shown in Figure 9, the SiN film 31 is removed by wet etching using buffered hydrofluoric acid.

[0041] Next, as shown in Figure 10, a first passivation film 41 is deposited on the p-type contact layer 24, the bottom surface and the side surface of the groove 71 by plasma CVD. The first passivation film 41 is, for example, a SiN film. An SiO2 film may be used instead of a SiN film. The thickness of the first passivation film 41 is, for example, 100 nm to 400 nm.

[0042] Next, as shown in Figure 11, resin 51 is applied to the first passivation film 41 by spin coating, and the resin 51 is filled into the grooves 71. At this time, the grooves 71 are completely filled with resin 51. After this, the resin 51 is heat-cured. The resin 51 may be, for example, BCB resin or polyimide resin. In this case, it is easy to fill the grooves 71 with resin 51 by coating.

[0043] Next, as shown in Figure 12, the resin 51 on the p-type contact layer 24 is removed by dry etching using a mixed gas of fluorine-based gas and oxygen gas, exposing the first passivation film 41. This makes the upper surface of the first passivation film 41 and the upper surface of the resin 51 flush or nearly flush. Examples of fluorine-based gases include CF4 gas and SF6 gas.

[0044] Next, as shown in Figure 13, a second passivation film 42 is deposited on the first passivation film 41 and the resin 51 by plasma CVD. In this case, etching of the resin 51 is easily suppressed when removing the SiN film 34 used as an etching mask when forming the grooves 72. The second passivation film 42 is, for example, a SiN film. An SiO2 film may be used instead of a SiN film. The thickness of the second passivation film 42 is, for example, 50 nm to 200 nm.

[0045] Next, as shown in Figure 14, a photoresist is applied to the second passivation film 42, and a resist pattern 33 is formed by exposure and development using an exposure apparatus. The thickness of the resist pattern 33 is, for example, 1 μm to 2 μm. The resist pattern 33 has openings 33a in the region excluding the grooves 71.

[0046] Next, as shown in Figure 15, the first passivation film 41 and the second passivation film 42 at the opening 33a of the resist pattern 33 are removed by wet etching using buffered hydrofluoric acid.

[0047] Next, as shown in Figure 16, the resist pattern 33 is removed using an organic solvent or the like.

[0048] Next, grooves 72 for pixel separation are formed. First, as shown in Figure 17, a SiN film 34 is deposited on the p-type contact layer 24, on the side surface of the first passivation film 41, and on the top and side surfaces of the second passivation film 42 by plasma CVD. The SiN film 34 is a film whose etching rate with respect to buffered hydrofluoric acid is greater than that of the first passivation film 41 and the second passivation film 42. For example, by setting the deposition temperature of the SiN film 34 lower than that of the first passivation film 41 and the second passivation film 42, a SiN film 34 with an etching rate with respect to buffered hydrofluoric acid greater than that of the first passivation film 41 and the second passivation film 42 can be deposited. The SiN film 34 may be a film whose etching rate with respect to buffered hydrofluoric acid is more than twice as great as that of the first passivation film 41 and the second passivation film. An SiO2 film may be used instead of the SiN film 34.

[0049] Next, as shown in Figure 18, a photoresist is applied to the SiN film 34, and a resist pattern 35 is formed by exposure and development using an exposure apparatus. At this time, since the grooves 71 are filled with resin 51, a thin resist pattern 35 can be used. Therefore, the openings 35a can be formed with good dimensional accuracy. As a result, mesas 70 that are separated by grooves 72 to form pixels can be formed with good dimensional accuracy. In contrast, if the grooves 71 are not filled with resin 51, it is necessary to apply photoresist so as to cover the bottom and sides of the grooves 71. Therefore, it is difficult to form openings in the photoresist with good dimensional accuracy. The thickness of the resist pattern 35 is, for example, 1 μm to 2 μm. The resist pattern 35 has openings 35a in the region where the grooves 72 are formed.

[0050] Next, as shown in Figure 19, the SiN film 34 at the openings 35a of the resist pattern 35 is removed by dry etching using a fluorine-based gas, and an etching mask is formed using the SiN film 34. Examples of fluorine-based gases include CF4 gas and SF6 gas.

[0051] Next, as shown in Figure 20, the resist pattern 35 is removed using an organic solvent or the like.

[0052] Next, as shown in Figure 21, a portion of the p-type contact layer 24, p-type wide gap layer 23b, and n-type wide gap layer 23a in the region where the SiN film 34 has been removed is removed by dry etching using a halogen-based gas to form a groove 72. In the groove 72, the n-type wide gap layer 23a is exposed at the bottom, and the n-type wide gap layer 23a, p-type wide gap layer 23b, and p-type contact layer 24 are exposed on the sides. Each pixel is formed by the mesa 70 separated by the groove 72. Damage layers, not shown, may occur on the exposed surfaces of the n-type wide gap layer 23a, p-type wide gap layer 23b, and p-type contact layer 24 due to dry etching. Examples of halogen-based gases are Cl2 gas and SiCl4 gas.

[0053] Next, as shown in Figure 22, the damaged layer generated during the formation of the groove 72 is removed using a hydrochloric acid-based etching solution. In this case, the damaged layer generated during the formation of the groove 72 can be removed. At this time, the n-type wide gap layer 23a is left at the bottom surface of the groove 72. The hydrochloric acid-based etching solution is, for example, HCl.

[0054] Next, as shown in Figure 23, the SiN film 34 is removed by wet etching using buffered hydrofluoric acid. At this time, the first passivation film 41 formed on the bottom and sides of the groove 71 and the second passivation film 42 formed on the resin 51 are left intact. For example, if the SiN film 34 has an etching rate to buffered hydrofluoric acid that is more than twice as large as that of the first passivation film 41 and the second passivation film 42, it is easy to leave the second passivation film 42 even when considering over-etching.

[0055] Next, as shown in Figure 24, a third passivation film 43 is deposited by plasma CVD on the p-type contact layer 24, the side surface of the first passivation film 41, the top and side surfaces of the second passivation film 42, and the bottom and side surfaces of the groove 72. At this time, the damage layer on the exposed surfaces of the n-type wide gap layer 23a, the p-type wide gap layer 23b, and the p-type contact layer 24 is removed, and the third passivation film 43 can be deposited while the surface remains undamaged, thus reducing leakage current. On the other hand, when forming a groove 71 for electrode extraction after forming a groove 72 for forming pixels, a SiN film or SiO2 film for etching mask to form the groove 71 is deposited after the damage layer has been removed. As a result, when the SiN film or SiO2 film for etching mask is deposited, damage occurs on the side surfaces of the mesa 70 that forms pixels (the exposed surfaces of the n-type wide gap layer 23a, the p-type wide gap layer 23b, and the p-type contact layer 24), and this damage remains. As a result, the leakage current increases. Furthermore, if an attempt is made to remove the damage layer after forming the groove 71 but before depositing the passivation film covering the groove 72, the upper surface of the mesa 70 is exposed, causing part or all of the p-type contact layer 24 to be etched, making it impossible to remove the damage layer. The third passivation film 43 is, for example, a SiN film. An SiO2 film may be used instead of a SiN film. The thickness of the third passivation film 43 is, for example, 100 nm to 400 nm.

[0056] Next, as shown in Figure 25, a photoresist is applied to the third passivation film 43, and a resist pattern 36 is formed by exposure and development using an exposure apparatus. The resist pattern 36 has an opening 36a in the region where the n electrode 61 is formed. When viewed from a direction perpendicular to the first main surface 10a, for example, the opening 36a is formed in a position that overlaps with at least a part of the region where the resin 51 is provided. The width of the opening 36a may be narrower than, for example, the width of the groove 71.

[0057] Next, as shown in Figure 26, the third passivation film 43, the second passivation film 42, the resin 51, and the first passivation film 41 in the opening 36a of the resist pattern 36 are removed by dry etching using a fluorine-based gas. This forms a groove 73. Since the width of the opening 36a is narrower than the width of the groove 71, the first passivation film 41 and the resin 51 remain on both sides of the groove 73. As a result, the sides of the n-type contact layer 21, the light-receiving layer 22, the n-type wide gap layer 23a, the p-type wide gap layer 23b, and the p-type contact layer 24 are not exposed to the fluorine-based gas during dry etching. Consequently, the sides of the n-type contact layer 21, the light-receiving layer 22, the n-type wide gap layer 23a, the p-type wide gap layer 23b, and the p-type contact layer 24 are not damaged. In the groove 73, the n-type contact layer 21 is exposed at the bottom, and the first passivation film 41, resin 51, second passivation film 42, and third passivation film 43 are exposed on the sides. The fluorine-based gas is, for example, CF4 gas or SF6 gas.

[0058] Next, as shown in Figure 27, the resist pattern 36 is removed using an organic solvent or the like.

[0059] Next, as shown in Figure 28, a portion of the third passivation film 43 in the mesa 70 is removed to expose the p-type contact layer 24. Specifically, a photoresist is applied on the third passivation film 43, and a resist pattern (not shown) is formed by exposure and development using an exposure apparatus. The resist pattern has openings in the region where the p-electrode 62 is formed, and the third passivation film 43 at the openings in the resist pattern is removed by dry etching to expose the surface of the p-type contact layer 24.

[0060] Next, as shown in Figure 29, an n-electrode 61 is formed on the n-type contact layer 21, on the side surface of the groove 73, and on the third passivation film 43 in the outer mesa 74, and a p-electrode 62 is formed on the p-type contact layer 24 in the mesa 70. The n-electrode 61 and p-electrode 62 are formed by the lift-off method. Specifically, a resist pattern having openings in the region where each electrode is formed is formed, a metal film is deposited by EB deposition, and then the resist pattern and the metal film on top of the resist pattern are removed by immersion in an organic solvent or the like. The n-electrode 61 and p-electrode 62 are formed, for example, by a laminated film of a Ti film, a Pt film, and an Au film.

[0061] Next, as shown in Figure 30, an anti-reflective film 80 is formed on the second main surface 10b of the substrate 10 by plasma CVD. The anti-reflective film 80 is, for example, a SiN film. A SiON film may be used instead of a SiN film. With the above steps, the light-receiving element 100 according to the embodiment can be manufactured.

[0062] As described above, according to the manufacturing method of the photodetector 100 according to the embodiment, the groove 72 for pixel separation is formed after the groove 71 for electrode extraction. In this case, when the SiN film or SiO2 film for the etching mask for forming the groove 71 is deposited, the side surface of the mesa 70 that forms the pixels is not exposed. Therefore, damage to the side surface of the mesa 70 during the deposition of the SiN film or SiO2 film for the etching mask for forming the groove 71 can be reduced. As a result, leakage current can be reduced.

[0063] In the above embodiment, the case in which the light-receiving element 100 is a two-dimensional array type was described, but the disclosure is not limited thereto. For example, the light-receiving element 100 may be an array in which pixels separated by grooves 72 are arranged in one dimension.

[0064] Although embodiments have been described in detail above, the invention is not limited to any particular embodiment, and various modifications and changes are possible within the scope described in the claims. [Explanation of Symbols]

[0065] 10 circuit boards 10a First main surface 10b Second main surface 21 n-type contact layer 22 Light-receiving layer 23 Wide gap layer 23a n-type wide gap layer 23b p-type wide gap layer 24 p-type contact layer 31 SiN film 32 Resist Patterns 32a opening 33 Resist Patterns 33a opening 34 SiN film 35 Resist Patterns 35a opening 36 Resist Patterns 36a opening 41 First Passivation Membrane 42 Second Passivation Membrane 43 Third Passivation Membrane 51 Resin 61 n electrode 62p electrode 70 Mesa 71 Groove 72 Groove 73 Groove 74 Mesa 80 Anti-reflective coating 100 light-receiving elements

Claims

1. A step of forming a first contact layer on one side of the substrate, A step of forming a light-receiving layer on the first contact layer, A step of forming a second contact layer on the light-receiving layer, A step of removing the second contact layer, the light-receiving layer, and a portion of the first contact layer to form a first groove in which the first contact layer is exposed, The process involves filling the first groove with resin, After the step of embedding the resin, the second contact layer is removed and a second groove is formed to separate the pixels. It has, The aforementioned resin is a benzocyclobutene resin or a polyimide resin. A method for manufacturing a light-receiving element.

2. A step of forming a first contact layer on one side of the substrate, A step of forming a light-receiving layer on the first contact layer, A step of forming a second contact layer on the light-receiving layer, A step of removing the second contact layer, the light-receiving layer, and a portion of the first contact layer to form a first groove in which the first contact layer is exposed, The process involves filling the first groove with resin, A step of forming an insulating film on the resin, After the step of forming the insulating film, the second contact layer is removed and a second groove is formed to separate the pixels. A method for manufacturing a light-receiving element having the following characteristics.

3. The process further comprises the step of removing the damaged layer after the step of forming the second groove, A method for manufacturing a light-receiving element according to claim 1 or claim 2.

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