Light-receiving device

Abstract

To provide a light-receiving device with a reduced size.SOLUTION: A light-receiving device according to the present invention includes a first light-receiving element and a second light-receiving element each having a semiconductor substrate including a light-receiving region, and a support substrate including a support surface that supports the first light-receiving element and the second light-receiving element. The semiconductor substrate on one side in one of the first light-receiving element and the second light-receiving element further includes a main surface including the light-receiving region, a back surface on the opposite side of the main surface in a perpendicular direction, and a concave part depressed from the back surface to the main surface. The semiconductor substrate on the other side in the other of the first light-receiving element and the second light-receiving element is disposed inside the concave part. The angle θ between the support surface and a side surface connecting from an opening end of the concave part to a bottom surface of the concave part is 75° or more and 105° or less.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a light receiving device. [Background technology]

[0002] Conventionally, a light receiving device is known that includes a plurality of light receiving elements that receive a plurality of types of light having different wavelength bands (see, for example, Patent Document 1). In the light receiving device disclosed in Patent Document 1, the plurality of light receiving elements are stacked. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-12713 Summary of the Invention [Problem to be solved by the invention]

[0004] The thickness of the light receiving device disclosed in Patent Document 1 increases depending on the thickness of each light receiving element, so there is room for improvement in terms of miniaturizing the light receiving device.

[0005] An object of one aspect of the present invention is to provide a light-receiving device that is miniaturized. [Means for solving the problem]

[0006] One aspect of the present invention is a first light receiving element and a second light receiving element each having a semiconductor substrate including a light receiving region; a support substrate having a support surface that supports the first light receiving element and the second light receiving element; Equipped with the semiconductor substrate on one side of one of the first light receiving element and the second light receiving element further has a main surface including the light receiving region, a back surface opposite to the main surface in a direction perpendicular to the surface, and a recess recessed from the back surface toward the main surface; the semiconductor substrate on the other side of the other of the first light receiving element and the second light receiving element is disposed inside the recess, The angle θ formed between the side surface connecting the opening end of the recess to the bottom surface of the recess and the support surface is 75° or more and 105° or less. It is a light receiving device. [Effects of the Invention]

[0007] According to one aspect of the present invention, the light receiving device can be made smaller. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a plan view schematically showing a light receiving device according to a first embodiment. [Figure 2] 2 is a cross-sectional view showing a schematic cross section of the light receiving device according to the first embodiment taken along line II-II shown in FIG. [Figure 3] 10 is a cross-sectional view showing a schematic cross section of the light receiving device cut along the XZ plane in the first embodiment, in which the angle θ formed between the side surface of the recess and the support surface of the support substrate is 75° or more and 90° or less. FIG. [Figure 4] 10 is a cross-sectional view showing a schematic cross section of a light receiving device cut along an XZ plane in the first embodiment, in which the angle θ formed between the side surface of a recess and the support surface of a support substrate is 90° or more and 105° or less. FIG. [Figure 5] 10 is a cross-sectional view showing a schematic cross section of a light receiving device according to Modification 1 of the first embodiment, taken along an XZ plane. FIG. [Figure 6] FIG. 10 is a plan view schematically showing a light receiving device according to a second modification of the first embodiment. [Figure 7] 7 is a cross-sectional view showing a schematic cross section of the light receiving device according to Modification 2 of the first embodiment taken along line VII-VII shown in FIG. 6. FIG. [Figure 8] 8 is a cross-sectional view showing a schematic cross section of the light receiving device according to Modification 2 of the first embodiment taken along line VIII-VIII shown in FIG. 6. FIG. [Figure 9]FIG. 10 is a plan view schematically showing a light receiving device according to a second embodiment. [Figure 10] 10 is a cross-sectional view showing a schematic cross section of the light receiving device according to the second embodiment taken along the line XX shown in FIG. 9. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail. To facilitate understanding of the description, the same components in the drawings will be designated by the same reference numerals, and duplicate descriptions will be omitted as appropriate. Furthermore, the scale of each component in the drawings may differ from the actual scale.

[0010] In drawings, directions may be indicated by the X-axis, Y-axis, and Z-axis. The X-axis, Y-axis, and Z-axis are perpendicular to each other. The direction in which an arrow points in the X-axis direction is referred to as the +X direction or +X side, and the direction opposite to the +X direction is referred to as the -X direction or -X side. The direction in which an arrow points in the Y-axis direction is referred to as the +Y direction or +Y side, and the direction opposite to the +Y direction is referred to as the -Y direction or -Y side. The direction in which an arrow points in the Z-axis direction is referred to as the +Z direction or +Z side, and the direction opposite to the +Z direction is referred to as the -Z direction or -Z side.

[0011] In the following embodiments, "parallel" to the X-axis, Y-axis, Z-axis, or other direction includes an error of ±5° when the object is tilted relative to these axes or directions. In the embodiments, "orthogonal" includes an error of ±5° relative to 90°. Furthermore, directions parallel to the X-axis and Y-axis directions may be referred to as "in-plane directions." Directions parallel to the Z-axis direction may be referred to as "perpendicular to the plane." The in-plane directions and perpendicular to the plane directions are mutually perpendicular.

[0012] [First embodiment] An example of the configuration of the light receiving device 1 according to the first embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a plan view schematically showing the light receiving device 1 according to the first embodiment. Fig. 2 is a cross-sectional view showing a schematic cross section of the light receiving device 1 taken along line II-II shown in Fig. 1. Note that Fig. 2 is an example of a cross-sectional view of the light receiving device 1 taken along a direction perpendicular to the surface so as to include a recess 17 of a first light receiving element 10, which will be described separately.

[0013] 1 and 2, the light receiving device 1 according to the first embodiment includes a first light receiving element 10, a second light receiving element 20, and a support substrate 30. The light receiving device 1 may further include an optical thin film such as an anti-reflection film that prevents reflection of light.

[0014] <First light receiving element 10> An example of the configuration of the first light receiving element 10 will be described. The first light receiving element 10 is, for example, a photoelectric conversion element such as a photodiode. The first light receiving element 10 has a first semiconductor substrate 11. The first semiconductor substrate 11 is an example of a "semiconductor substrate on one side." As shown in FIG. 1, the first semiconductor substrate 11 has a substantially rectangular shape in a plan view. Furthermore, as shown in FIG. 2, the first semiconductor substrate 11 has a main surface 11a, a back surface 11b, and a side surface 11c.

[0015] In the example shown in FIG. 2, the main surface 11a corresponds to the +Z side surface of the first semiconductor substrate 11. Light OP1 received by the first light receiving element 10 is incident from the main surface 11a. An anti-reflection film is preferably provided on the main surface 11a. The thickness and material of the anti-reflection film may be selected as appropriate. The back surface 11b is the surface opposite to the main surface 11a in the direction perpendicular to the surface. In other words, the back surface 11b corresponds to the -Z side surface of the first semiconductor substrate 11. The side surface 11c connects the outer edge of the main surface 11a to the outer edge of the back surface 11b.

[0016] The first semiconductor substrate 11 is made of a semiconductor material having a larger band gap than the material constituting the second semiconductor substrate 21 included in the second light receiving element 20, which will be described separately. For example, the first semiconductor substrate 11 receives visible light. An example of the material constituting the first semiconductor substrate 11 is silicon (Si). However, the material constituting the first semiconductor substrate 11 is not limited to Si. The first semiconductor substrate 11 has n-type conductivity, except for the light receiving region 12, which will be described separately.

[0017] The first semiconductor substrate 11 has a light-receiving region 12. As shown in FIGS. 1 and 2, the light-receiving region 12 is included in the main surface 11a of the first semiconductor substrate 11. The light-receiving region 12 corresponds to a p-type diffusion region doped with an acceptor element such as boron. In the first semiconductor substrate 11, the interface between the light-receiving region 12 and the remaining region other than the light-receiving region 12 corresponds to a p-n junction region. Light OP1 that reaches the p-n junction region is converted into electric charges.

[0018] Charges generated in the pn junction region in response to reception of light OP1 are extracted as a current to the outside via, for example, the anode electrode 14 and the cathode electrode 15, which are respectively disposed on the main surface 11a of the first semiconductor substrate 11. That is, a light reception signal from the first light receiving element 10 is output to the outside via the anode electrode 14 and the cathode electrode 15. In the example shown in FIGS. 1 and 2, the light reception signal from the first light receiving element 10 is output to the wiring 35 of the support substrate 30. The anode electrode 14 is connected to the light receiving region 12. The cathode electrode 15 is connected to the remaining region of the first semiconductor substrate 11 other than the light receiving region 12.

[0019] 2, the first semiconductor substrate 11 further has a recess 17. The recess 17 corresponds to a hollow space recessed from the back surface 11b toward the main surface 11a in the first semiconductor substrate 11. In the example shown in Fig. 2, the recess 17 has an opening end 17a on the back surface 11b side of the first semiconductor substrate 11, a bottom surface 17b on the +Z side of the opening end 17a, and a side surface 17c connecting from the opening end 17a to the bottom surface 17b.

[0020] The recess 17 may be formed by, for example, dry etching, a combination of dry etching and wet etching, or cutting using a cutting tool such as a blade. Here, in accordance with the formation of the recess 17, wall-like portions located on the sides of the recess 17 are formed in the first semiconductor substrate 11. Hereinafter, these wall-like portions will be referred to as "sidewall portions" of the first semiconductor substrate 11.

[0021] In the example shown in FIGS. 1 and 2, the first semiconductor substrate 11 has, as sidewalls, a first sidewall 18a on the −X side and a second sidewall 18b on the +X side. That is, in the example shown in FIGS. 1 and 2, the first semiconductor substrate 11 has two sidewalls. The first sidewall 18a and the second sidewall 18b face each other in the X-axis direction with the recess 17 in between. The recess 17 shown in FIGS. 1 and 2 has a trough-like shape along the Y-axis direction due to the first sidewall 18a and the second sidewall 18b. That is, both ends of the recess 17 in the Y-axis direction are open. However, the number of sidewalls is not limited to two. The number of sidewalls may be three or four.

[0022] The opening edge 17a is defined by the inner edge of the back surface 11b of the first semiconductor substrate 11. The bottom surface 17b is defined by the inner bottom surface of the first semiconductor substrate 11. The bottom surface 17b is, for example, a surface that extends in an in-plane direction. An anti-reflection film is preferably provided on the bottom surface 17b. In the example shown in FIG. 2, the side surface 17c has a first side surface 17c1 on the −X side and a second side surface 17c2 on the +X side. The first side surface 17c1 is defined by the inner surface of the first sidewall portion 18a of the first semiconductor substrate 11. The second side surface 17c2 is defined by the inner surface of the second sidewall portion 18b of the first semiconductor substrate 11.

[0023] As shown in FIG. 2, in a cross-sectional view including recess 17, when W1 is the length of bottom surface 17b and W2 is the length between opposing portions of opening end 17a, the ratio of W1 to W2, W1 / W2, is preferably 0.9 or greater. Furthermore, W1 / W2 is more preferably 0.95 or greater. Furthermore, W1 / W2 is even more preferably 1.0 or greater. Meanwhile, W1 / W2 is preferably 1.1 or less. Furthermore, W1 / W2 is more preferably 1.05 or less. That is, W1 / W2 is preferably 0.9 or greater and 1.1 or less, and more preferably 0.95 or greater and 1.05 or less. In the following description, W1 may be referred to as the "bottom width." Furthermore, W2 may be referred to as the "opening width."

[0024] When W1 / W2 is 1.0, as described separately, the angle θ between the side surface 17c of the recess 17 and the support surface 31a of the support substrate 30 is 90°. That is, the side surface 17c of the recess 17 extends in the perpendicular direction. Even when W1 / W2 is 0.9 or more and 1.1 or less, the side surface 17c of the recess 17 extends in the direction perpendicular to the support surface 31a. That is, the side surface 17c of the recess 17 is not inclined. This allows the in-plane size of the first semiconductor substrate 11 to be reduced without reducing the in-plane size of the second light receiving element 20 (second semiconductor substrate 21) disposed inside the recess 17. This allows the first light receiving element 10 and the light receiving device 1 to be reduced in size. Furthermore, the in-plane size of the second light receiving element 20 (second semiconductor substrate 21) can be increased without increasing the in-plane size of the first semiconductor substrate 11. This allows the amount of light received by the second light receiving element 20 to be increased.

[0025] <Second light receiving element 20> An example of the configuration of the second light receiving element 20 will be described. The second light receiving element 20 is, for example, a photoelectric conversion element such as a photodiode. As shown in FIGS. 1 and 2, the second light receiving element 20 is disposed inside a recess 17 of the first semiconductor substrate 11. The second light receiving element 20 has a second semiconductor substrate 21. The second semiconductor substrate 21 is an example of the "semiconductor substrate on the other side."

[0026] As shown in FIG. 1, the second semiconductor substrate 21 has a substantially rectangular shape in a plan view. Furthermore, as shown in FIG. 2, the second semiconductor substrate 21 has a main surface 21a, a back surface 21b, and a side surface 21c. In the example shown in FIG. 2, the main surface 21a corresponds to the +Z side surface of the second semiconductor substrate 21. Light OP2 received by the second light receiving element 20 is incident from the main surface 21a. An anti-reflection film is preferably provided on the main surface 21a. The back surface 21b is a surface opposite to the main surface 21a in the direction perpendicular to the surface. In other words, the back surface 21b corresponds to the -Z side surface of the second semiconductor substrate 21. The side surface 21c connects the outer edge of the main surface 21a to the outer edge of the back surface 21b.

[0027] The second semiconductor substrate 21 is made of a semiconductor material having a smaller band gap than the material constituting the first semiconductor substrate 11. For example, the second semiconductor substrate 21 receives infrared light. An example of a material constituting the second semiconductor substrate 21 is indium phosphide (InP). However, the material constituting the second semiconductor substrate 21 is not limited to InP. The second semiconductor substrate 21 has n-type conductivity except for the light-receiving region 22, which will be described separately.

[0028] The second semiconductor substrate 21 has a light-receiving region 22. As shown in FIGS. 1 and 2, the light-receiving region 22 is included in the main surface 21a of the second semiconductor substrate 21. In the example shown in FIG. 2, the main surface 21a of the second semiconductor substrate 21 including the light-receiving region 22 is on the +Z side, but may be on the -Z side. In this case, the back surface 21b of the second semiconductor substrate 21 is on the +Z side with respect to the main surface 21a.

[0029] The light-receiving region 22 is disposed at a position overlapping the light-receiving region 12 of the first semiconductor substrate 11 in a plan view. This allows the light-receiving region 22 to be disposed so as to intersect with the optical axis OL of the light OP1 to the light-receiving region 12. As a result, the second light-receiving element 20 can be disposed inside the recess 17 of the first semiconductor substrate 11, and arranged side by side with the first light-receiving element 10 in the Z-axis direction. In other words, even if the first light-receiving element 10 and the second light-receiving element 20 are arranged side by side in the Z-axis direction, the thickness of the light-receiving device 1 does not increase more than the thickness of the first light-receiving element 10. This allows the light-receiving device 1 to be made smaller in size.

[0030] The light-receiving region 22 corresponds to a region having p-type conductivity made of, for example, indium gallium arsenide (InGaAs). In the second semiconductor substrate 21, the interface between the light-receiving region 22 and the remaining region other than the light-receiving region 22 corresponds to a p-n junction region. Light OP2 that reaches the p-n junction region is converted into electric charges.

[0031] Charges generated in the pn junction region in response to reception of light OP2 are extracted as a current to the outside via, for example, the anode electrode 24 and the cathode electrode 25 of the second semiconductor substrate 21. That is, a light reception signal from the second light receiving element 20 is output to the outside via the anode electrode 24 and the cathode electrode 25. In the example shown in FIGS. 1 and 2, the light reception signal from the second light receiving element 20 is output to the wiring 36 of the support substrate 30. The anode electrode 24 is connected to the light receiving region 22. The cathode electrode 25 is connected to the remaining region of the second semiconductor substrate 21 other than the light receiving region 22.

[0032] <Support substrate 30> Next, an example of the configuration of the support substrate 30 will be described. The support substrate 30 supports the first light receiving element 10 and the second light receiving element 20. The support substrate 30 may also be a wiring substrate for transmitting light receiving signals output from the first light receiving element 10 and the second light receiving element 20 to the outside. In the example shown in FIGS. 1 and 2, the support substrate 30 includes a plurality of wirings 35 connected to the anode electrode 14 and the cathode electrode 15 of the first light receiving element 10, respectively, and a plurality of wirings 36 connected to the anode electrode 24 and the cathode electrode 15 of the second light receiving element 20, respectively. The wirings 35 are connected to the anode electrode 14 and the cathode electrode 15 via thin conductor wires such as bonding wires 19. The wirings 36 are connected to the anode electrode 24 via thin conductor wires such as bonding wires 19. Although wiring connected to the cathode electrode 25 of the second light receiving element 20 is not shown, it may be connected to the cathode electrode 25, for example, through wiring arranged in another location on the support substrate 30. The various wirings provided on the support substrate 30, such as the wiring 35 and the wiring 36, are connected to, for example, an external signal processing circuit.

[0033] As shown in FIG. 1, the support substrate 30 has a substantially rectangular shape in a plan view. Furthermore, as shown in FIG. 2, the support substrate 30 has a main surface 31a, a back surface 31b, and a side surface 31c. The main surface 31a corresponds to the +Z side surface of the support substrate 30. The main surface 31a is a surface that supports the first light receiving element 10 and the second light receiving element 20. The main surface 31a will be referred to as the "support surface 31a" hereinafter. The back surface 31b is a surface that is opposite to the support surface 31a in the direction perpendicular to the surface. In other words, the back surface 31b corresponds to the -Z side surface of the support substrate 30. The side surface 31c connects the outer edge of the support surface 31a to the outer edge of the back surface 31b.

[0034] Examples of materials that can be used to form the support substrate 30 include glass epoxy, ceramic, and resin, but the material that can be used to form the support substrate 30 is not limited to these.

[0035] <Angle θ between the side surface 17c of the recess 17 and the support surface 31a of the support substrate 30> Next, the angle θ formed between the side surface 17c of the recess 17 and the support surface 31a of the support substrate 30 will be described. In the example shown in FIG. 2, the angle θ corresponds to the angle between the first side surface 17c1 of the recess 17 and the support surface 31a, and the angle between the second side surface 17c2 of the recess 17 and the support surface 31a. The angle θ formed between the first side surface 17c1 of the recess 17 and the support surface 31a is an example of "angle θ1." The angle θ formed between the second side surface 17c2 of the recess 17 and the support surface 31a is an example of "angle θ2."

[0036] The angle θ between the first side surface 17c1 of the recess 17 and the support surface 31a and the angle θ between the second side surface 17c2 of the recess 17 and the support surface 31a may be the same or different. However, each angle θ must satisfy the conditions for angle θ that will be described separately. In the following description, it is assumed that the angle θ between the first side surface 17c1 of the recess 17 and the support surface 31a is the same as the angle θ between the second side surface 17c2 of the recess 17 and the support surface 31a.

[0037] The angle θ is 75° or greater and 105° or less. The angle θ is more preferably 80° or greater and 100° or less. The angle θ is more preferably 85° or greater and 95° or less. The angle θ is preferably 90°. By setting the angle θ to 75° or greater and 105° or less, the side surface 17c of the recess 17 can be aligned substantially perpendicular to the surface. That is, the side surface 17c of the recess 17 can be substantially not inclined. This allows the in-plane size of the first semiconductor substrate 11 to be reduced without reducing the in-plane size of the second semiconductor substrate 21. As a result, the first light receiving element 10 and the light receiving device 1 can be miniaturized. Furthermore, the in-plane size of the second semiconductor substrate 21 can be increased without increasing the in-plane size of the first semiconductor substrate 11. This allows the light receiving area 22 of the second semiconductor substrate 21 to be increased, thereby increasing the amount of light received by the second light receiving element 20.

[0038] Furthermore, when the angle θ is equal to or greater than 90° and equal to or less than 105°, the light OP2 reflected by the side surface 17c of the recess 17 can be made incident on the light receiving region 22 of the second semiconductor substrate 21 (see FIG. 4). This also makes it possible to increase the amount of light received by the second light receiving element 20.

[0039] <Distance between recess 17 of first semiconductor substrate 11 and second semiconductor substrate 21> Next, the distance between the recess 17 of the first semiconductor substrate 11 and the second semiconductor substrate 21 will be described with reference to FIGS. 3 and 4. FIG. 3 is a cross-sectional view showing a schematic cross section of the light receiving device 1 cut along the XZ plane when the angle θ formed between the side surface 17c of the recess 17 and the support surface 31a is 75° or more and 90° or less. FIG. 4 is a cross-sectional view showing a schematic cross section of the light receiving device 1 cut along the XZ plane when the angle θ formed between the side surface 17c of the recess 17 and the support surface 31a is 90° or more and 105° or less. FIGS. 3 and 4 are examples of cross-sectional views of the light receiving device 1 cut along the perpendicular direction to include the recess 17.

[0040] 3 and 4 , in a cross-sectional view of the light-receiving device 1 cut along the direction perpendicular to the surface so as to include the recess 17, the distance "G1" corresponds to the distance between an end 21c1 of the side surface 21c of the second semiconductor substrate 21 on the main surface 21a side and the side surface 17c of the recess 17. One example of the distance G1 is the distance between the end 21c1 of the side surface 21c on the -X side of the second semiconductor substrate 21 and the intersection of an extension line extending parallel to the in-plane direction from the end 21c1 and the first side surface 17c1 of the recess 17.

[0041] 3 and 4, in a cross-sectional view of the light-receiving device 1 cut along the direction perpendicular to the surface so as to include the recess 17, the distance "G2" corresponds to the distance between an end 21c2 on the back surface 21b side of the side surface 17c of the second semiconductor substrate 21 and the side surface 17c of the recess 17. An example of the distance G2 is the distance between the end 21c2 on the side surface 21c on the -X side of the second semiconductor substrate 21 and the intersection of an extension line extending parallel to the in-plane direction from the end 21c2 and the first side surface 17c1 of the recess 17.

[0042] As shown in Fig. 3, when the angle θ formed between the side surface 17c of the recess 17 and the support surface 31a is 75° or more and 90° or less, the ratio G1 / G2 of the gap G1 to the gap G2 is preferably 0.9 or more and 1.0 or less. Also, as shown in Fig. 4, when the angle θ formed between the side surface 17c of the recess 17 and the support surface 31a is 90° or more and 105° or less, the ratio G1 / G2 is preferably 1 or more and 1.1 or less. That is, the ratio G1 / G2 is preferably 0.9 or more and 1.1 or less.

[0043] By setting G1 / G2 to be equal to or greater than 0.9 and equal to or less than 1.1, the size of the first semiconductor substrate 11 in the in-plane direction can be reduced without reducing the size of the second semiconductor substrate 21 in the in-plane direction. As a result, the first light receiving element 10 and the light receiving device 1 can be made smaller. Also, the size of the second semiconductor substrate 21 in the in-plane direction can be increased without increasing the size of the first semiconductor substrate 11 in the in-plane direction. This allows the light receiving region 22 of the second semiconductor substrate 21 to be increased, and the amount of light received by the second light receiving element 20 to be increased.

[0044] <Comparison with comparative examples> Next, the advantageous effects of the light receiving device 1 compared to the following Comparative Examples 1 and 2 will be described. First, the comparison with Comparative Example 1 will be described. Comparative Example 1 is an example in which the angle θ between the side surface 17c of the recess 17 and the support surface 31a corresponds to 70°. In other words, Comparative Example 1 is an example in which the ratio W1 / W2, which is the ratio of the bottom width W1 to the opening width W2 of the recess 17, corresponds to 0.8. The other configurations of Comparative Example 1 are the same as those of the light receiving device 1.

[0045] In Comparative Example 1, the angle θ between the side surface 17c of the recess 17 and the support surface 31a is 70°, so the degree of inclination of the side surface 17c of the recess 17 relative to the support surface 31a is relatively large. As a result, if the side surface 17c of the recess 17 and the second semiconductor substrate 21 of the second light receiving element 20 are close to each other, they come into contact with each other. To avoid this contact, it is necessary to increase the opening width W2 of the recess 17 or reduce the in-plane size of the second semiconductor substrate 21. As a result, the first semiconductor substrate 11 becomes larger, or the amount of light received by the second light receiving element 20 decreases as the second semiconductor substrate 21 becomes smaller. Furthermore, the volume of the space between the side surface 17c of the recess 17 and the second semiconductor substrate 21 increases. That is, the volume of the space within the recess 17 where the second light receiving element 20 is not disposed increases. Therefore, Comparative Example 1 still has room for improvement in terms of obtaining a space-saving recess 17. In contrast, in the light-receiving device 1, the angle θ between the side surface 17c of the recess 17 and the support surface 31a is between 75° and 105°, so the side surface 17c of the recess 17 is not inclined at all with respect to the support surface 31a. This makes it possible to increase the size of the second semiconductor substrate 21 in the in-plane direction without increasing the size of the first semiconductor substrate 11 in the in-plane direction. In addition, it is possible to prevent an excessive increase in the volume of the space in the recess 17 where the second light-receiving element 20 is not disposed.

[0046] Next, a comparison with Comparative Example 2 will be described. Comparative Example 2 is an example in which the angle θ between the side surface 17c of the recess 17 and the support surface 31a corresponds to 110°. In other words, Comparative Example 2 is an example in which the ratio W1 / W2, which is the ratio of the bottom width W1 to the opening width W2 of the recess 17, corresponds to 1.2. Other configurations of Comparative Example 2 are the same as those of the light receiving device 1.

[0047] In Comparative Example 2, the bottom width W1 of the recess 17 is longer than the opening width W2. Furthermore, in Comparative Example 2, the angle θ between the side surface 17c of the recess 17 and the support surface 31a is 110°, so the degree of inclination of the side surface 17c of the recess 17 relative to the support surface 31a is relatively large. As a result, if the side surface 17c of the recess 17 and the second semiconductor substrate 21 of the second light receiving element 20 are close to each other, they will come into contact with each other. To avoid this contact, it is necessary to increase the bottom width W1 of the recess 17 or reduce the size of the second semiconductor substrate 21 in the in-plane direction. This results in an increase in the size of the first semiconductor substrate 11, or a decrease in the amount of light received by the second light receiving element 20 due to the miniaturization of the second semiconductor substrate 21. Furthermore, the volume of the space between the side surface 17c of the recess 17 and the second semiconductor substrate 21 increases. That is, the volume of the space within the recess 17 where the second light receiving element 20 is not disposed increases. Therefore, there is room for improvement in terms of obtaining a space-saving recess 17. In contrast, in the light-receiving device 1, the angle θ between the side surface 17c of the recess 17 and the support surface 31a is 75° or more and 105° or less, and the side surface 17c of the recess 17 is hardly inclined with respect to the support surface 31a. Therefore, it is possible to increase the size of the second semiconductor substrate 21 in the in-plane direction without increasing the size of the first semiconductor substrate 11 in the in-plane direction. In addition, it is possible to reduce an increase in the volume of the space in the recess 17 where the second light-receiving element 20 is not disposed.

[0048] Furthermore, in the recess 17 of Comparative Example 2, the bottom width W1 is larger than the opening width W2, which increases the difficulty of forming the recess 17 with such a shape by etching or cutting. In contrast, in the recess 17 of the light-receiving device 1, the bottom width W1 and the opening width W2 are approximately the same length, which makes it easy to form the recess 17. This allows the cost of forming the recess 17 in the light-receiving device 1 to be reduced.

[0049] [Variation 1] Next, a light receiving device 1A according to Modification 1 of the first embodiment will be described with reference to Fig. 5. Fig. 5 is a cross-sectional view showing a schematic cross section of the light receiving device 1A according to Modification 1 taken along the XZ plane. Note that components similar to those in the first embodiment are given the same reference numerals, and descriptions thereof will be omitted where appropriate. Fig. 5 is an example of a cross-sectional view of the light receiving device 1A taken along the direction perpendicular to the surface so as to include the recess 17.

[0050] In the light receiving device 1A according to the first modification, the configuration of the side surface 17c of the recess 17 differs from that of the first embodiment. Specifically, as shown in FIG. 5, the first side surface 17c1 and the second side surface 17c2 are inclined in the same direction. However, the angle θ on the first side surface 17c1 side and the angle θ on the second side surface 17c2 side are each between 75° and 105°. For example, when the angle θ on the first side surface 17c1 side is 105°, the angle θ on the second side surface 17c2 side is 75°.

[0051] In the first modification, the first side surface 17c1 and the second side surface 17c2 are inclined in the same direction, which facilitates the formation of the recess 17. Furthermore, the light receiving device 1A according to the first modification has the same effects as the light receiving device 1 according to the first embodiment.

[0052] [Variation 2] Next, a light receiving device 1B according to Modification 2 of the first embodiment will be described with reference to FIGS. 6 to 8. FIG. 6 is a plan view schematically showing the light receiving device 1B according to Modification 2. FIG. 7 is a cross-sectional view showing a schematic cross section of the light receiving device 1B taken along line VII-VII shown in FIG. 6. FIG. 8 is a cross-sectional view showing a schematic cross section of the light receiving device 1B taken along line VIII-VIII shown in FIG. 6. Note that components similar to those in the first embodiment and Modification 1 are denoted by the same reference numerals, and descriptions thereof will be omitted where appropriate. FIGS. 7 and 8 are examples of cross-sectional views of the light receiving device 1B taken along the direction perpendicular to the surface so as to include the recess 17.

[0053] The light-receiving device 1B according to the second modification is different from the first embodiment in that the first semiconductor substrate 11 has four sidewalls. Specifically, the first semiconductor substrate 11 has a first sidewall 18a and a second sidewall 18b that face each other in the X-axis direction, as well as a third sidewall 18c and a fourth sidewall 18d that face each other in the Y-axis direction.

[0054] 6, the third side wall 18c connects one end of the first side wall 18a and one end of the second side wall 18b. The fourth side wall 18d connects the other end of the first side wall 18a and one end of the second side wall 18b. The first side wall 18a, the second side wall 18b, the third side wall 18c, and the fourth side wall 18d form a frame that surrounds the recess 17.

[0055] As shown in FIG. 7, the angle θ between the first side surface 17c1 of the recess 17, defined by the inner surface of the first side wall 18a, and the support surface 31a, and the angle θ between the second side surface 17c2 of the recess 17, defined by the inner surface of the second side wall 18b, and the support surface 31a, are both 75° or more and 105° or less. Also, as shown in FIG. 8, the angle θ between the third side surface 17c3 of the recess 17, defined by the inner surface of the third side wall 18c, and the support surface 31a, and the angle θ between the fourth side surface 17c4 of the recess 17, defined by the inner surface of the fourth side wall 18d, and the support surface 31a, are both 75° or more and 105° or less. The angle θ between the third side surface 17c3 of the recess 17 and the support surface 31a is an example of the "angle θ3." The angle θ between the fourth side surface 17c4 of the recess 17 and the support surface 31a is an example of the "angle θ4."

[0056] In Modification 2, the angle θ between the third side surface 17c3 of the recess 17 and the support surface 31a and the angle θ between the fourth side surface 17c4 of the recess 17 and the support surface 31a are both 75° or more and 105° or less, so the sizes of the second semiconductor substrate 21 in the X-axis direction and the Y-axis direction can be increased without increasing the sizes of the first semiconductor substrate 11 in the X-axis direction and the Y-axis direction. This makes it possible to further increase the amount of light received by the second light receiving element 20. Furthermore, the light receiving device 1B according to Modification 2 achieves the same effects as the light receiving device 1 according to the first embodiment.

[0057] [Second embodiment] Next, a light receiving device 2 according to a second embodiment will be described with reference to FIGS. 9 and 10. FIG. 9 is a plan view schematically illustrating the light receiving device 2 according to the second embodiment. FIG. 10 is a cross-sectional view showing a schematic cross section of the light receiving device 2 taken along line XX shown in FIG. 9. Note that components similar to those in the first embodiment and modified examples 1 and 2 of the first embodiment are given the same reference numerals, and descriptions thereof will be omitted where appropriate. FIG. 10 is an example of a cross-sectional view of the light receiving device 2 taken along the direction perpendicular to the surface so as to include a recess 27 of a second light receiving element 20A, which will be described separately.

[0058] As shown in FIGS. 9 and 10 , the light-receiving device 2 according to the second embodiment includes a first light-receiving element 10A, a second light-receiving element 20A, and a support substrate 30. The second embodiment differs from the first embodiment in that the second semiconductor substrate 21A of the second light-receiving element 20A has a recess 27. The first semiconductor substrate 11A of the first light-receiving element 10A does not have a recess. Except for the lack of a recess, the configurations of the first semiconductor substrate 11A and the first light-receiving element 10A may be similar to the configurations of the first semiconductor substrate 11 and the first light-receiving element 10 according to the first embodiment. In the second embodiment, the second semiconductor substrate 21A is an example of a "semiconductor substrate on one side." The first semiconductor substrate 11A is an example of a "semiconductor substrate on the other side."

[0059] 9, the anode electrode 14 and the cathode electrode 15 of the first light receiving element 10A may each be electrically connected to wiring 39 of the support substrate 30 via a thin conductor wire such as a bonding wire 19 and an intermediate wiring 29 provided on the second semiconductor substrate 21A. The wiring 39 is connected to, for example, an external signal processing circuit.

[0060] 10, the second semiconductor substrate 21A has a main surface 23a, a back surface 23b, and a side surface 23c. In the example shown in FIG. 10, the main surface 23a corresponds to the -Z side surface of the second semiconductor substrate 21A. The back surface 23b is the surface opposite to the main surface 23a in the direction perpendicular to the surface. In other words, the back surface 23b corresponds to the +Z side surface of the second semiconductor substrate 21A. The side surface 23c connects the outer edge of the main surface 23a to the outer edge of the back surface 23b.

[0061] The second semiconductor substrate 21A further has a recess 27. The recess 27 corresponds to a hollow space recessed from the back surface 23b toward the main surface 23a. In the example shown in Fig. 10, the recess 27 has an opening edge 27a on the back surface 23b side of the second semiconductor substrate 21A, a bottom surface 27b on the -Z side of the opening edge 27a, and a side surface 27c connecting from the opening edge 27a to the bottom surface 27b.

[0062] The recess 27 may be formed by, for example, dry etching, a combination of dry etching and wet etching, or cutting using a cutting tool such as a blade. Here, in accordance with the formation of the recess 27, wall-like portions located on the sides of the recess 27 are formed in the second semiconductor substrate 21A. Hereinafter, these wall-like portions will be referred to as "sidewall portions" of the second semiconductor substrate 21A.

[0063] In the example shown in FIGS. 9 and 10 , the second semiconductor substrate 21A has, as sidewalls, a first sidewall 28a on the −X side and a second sidewall 28b on the +X side. That is, in the example shown in FIGS. 9 and 10 , the second semiconductor substrate 21A has two sidewalls. The first sidewall 28a and the second sidewall 28b face each other in the X-axis direction with the recess 27 in between. The recess 27 shown in FIGS. 9 and 10 has a trough-like shape along the Y-axis direction due to the first sidewall 28a and the second sidewall 28b. That is, both ends of the recess 27 in the Y-axis direction are open. However, the number of sidewalls is not limited to two. The number of sidewalls may be three or four.

[0064] The opening edge 27a is defined by the inner edge of the back surface 23b of the second semiconductor substrate 21A. The bottom surface 27b is defined by the inner bottom surface of the second semiconductor substrate 21A. The bottom surface 27b is, for example, a surface that extends in an in-plane direction. An anti-reflection film is preferably provided on the bottom surface 27b. In the example shown in FIG. 10, the side surface 27c has a first side surface 27c1 on the −X side and a second side surface 27c2 on the +X side. The first side surface 27c1 is defined by the inner surface of the first sidewall portion 28a of the second semiconductor substrate 21A. The second side surface 27c2 is defined by the inner surface of the second sidewall portion 28b of the second semiconductor substrate 21A.

[0065] As shown in FIG. 10, in a cross-sectional view including recess 27, when W1 is the length (bottom width) of bottom surface 27b and W2 is the length between opposing portions of opening edge 27a (opening width), the ratio of W1 to W2, W1 / W2, is preferably 0.9 or greater. Furthermore, W1 / W2 is more preferably 0.95 or greater. Furthermore, W1 / W2 is even more preferably 1.0 or greater. Meanwhile, W1 / W2 is preferably 1.1 or less. Furthermore, W1 / W2 is more preferably 1.05 or less. That is, W1 / W2 is preferably 0.9 or greater and 1.1 or less, and more preferably 0.95 or greater and 1.05 or less.

[0066] Furthermore, the angle θ between the side surface 27c of the recess 27 and the support surface 31a is 75° or more and 105° or less. In the example shown in FIG. 10 , the angle θ between the first side surface 27c1 of the recess 27 and the support surface 31a is 75° or more and 105° or less. Furthermore, the angle θ between the second side surface 27c2 of the recess 27 and the support surface 31a is 75° or more and 105° or less. The angle θ between the first side surface 27c1 of the recess 27 and the support surface 31a is an example of the "angle θ1." The angle θ between the second side surface 27c2 of the recess 27 and the support surface 31a is an example of the "angle θ2." The angle θ between the first side surface 27c1 of the recess 27 and the support surface 31a and the angle θ between the second side surface 27c2 of the recess 27 and the support surface 31a may be the same as or different from each other. Furthermore, even in the case where the second semiconductor substrate 21A has other side wall portions, the angle formed between the side surface region of the side surface 27c of the recess 27, which is defined by the inner surface of the other side wall portion, and the support surface 31a is also 75° or more and 105° or less.

[0067] Furthermore, it is preferable that the ratio G1 / G2 of the distance G1 between the end 11c1 on the main surface 11a side of the side 11c of the first semiconductor substrate 11A and the side 27c of the recess 27 and the distance G2 between the end 11c2 on the back surface 11b side of the side 11c of the first semiconductor substrate 11A and the side 27c of the recess 27 be greater than or equal to 0.9 and less than or equal to 1.1.

[0068] The light receiving device 2 according to the second embodiment has the same effects as the light receiving device 1 according to the first embodiment.

[0069] Although the embodiments have been described above, they are presented as examples and the present invention is not limited to the above embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as set forth in the claims.

[0070] The embodiments of the present invention are as follows, for example. <1> a first light receiving element and a second light receiving element each having a semiconductor substrate including a light receiving region; a support substrate having a support surface that supports the first light receiving element and the second light receiving element; Equipped with the semiconductor substrate on one side of one of the first light receiving element and the second light receiving element further has a main surface including the light receiving region, a back surface opposite to the main surface in a direction perpendicular to the surface, and a recess recessed from the back surface toward the main surface; the semiconductor substrate on the other side of the other of the first light receiving element and the second light receiving element is disposed inside the recess, The angle θ formed between the side surface connecting the opening end of the recess to the bottom surface of the recess and the support surface is 75° or more and 105° or less. Light receiving device. <2> In a cross-sectional view of the light receiving device cut along the direction perpendicular to the surface, when a length of the bottom surface of the recess is W1 and a length between opposing portions of the opening end of the recess is W2, W1 / W2, which is a ratio of W1 to W2, is 0.9 or more and 1.1 or less. The aforementioned <1> The light receiving device according to claim 1. <3> the other semiconductor substrate has a main surface including the light receiving region, a back surface opposite to the main surface in the direction perpendicular to the surface, and a side surface connecting the main surface and the back surface and facing a side surface of the recess, In a cross-sectional view of the light-receiving device cut along the direction perpendicular to the surface, when a distance between an end of the side surface of the semiconductor substrate on the other side on the main surface side and the side surface of the recess is defined as G1 and a distance between an end of the side surface of the semiconductor substrate on the other side on the back surface side and the side surface of the recess is defined as G2, The ratio G1 / G2 of G1 to G2 is 0.9 or more and 1.1 or less. The aforementioned <1> The light receiving device according to claim 1. <4> the semiconductor substrate on one side has a first sidewall portion and a second sidewall portion that face each other with the recessed portion therebetween, an angle θ1 between a first side surface of the recess defined by the inner surface of the first side wall portion and the support surface is equal to or greater than 75° and equal to or less than 105°; An angle θ2 formed between a second side surface of the recess defined by the inner surface of the second side wall portion and the support surface is 75° or more and 105° or less. The aforementioned <1> From the above <3> 10. The light receiving device according to claim 9, wherein: <5> the semiconductor substrate on one side further includes a third sidewall portion connecting one ends of the first sidewall portion and the second sidewall portion, and a fourth sidewall portion connecting other ends of the first sidewall portion and the second sidewall portion, an angle θ3 formed between a third side surface of the recess defined by the inner surface of the third side wall portion and the support surface is equal to or greater than 75° and equal to or less than 105°; an angle θ4 formed between a fourth side surface of the recess defined by the inner surface of the fourth side wall portion and the support surface is equal to or greater than 75° and equal to or less than 105°; The aforementioned <4> The light receiving device according to claim 1. [Explanation of symbols]

[0071] 1,1A,1B,2 Photodetector 10,10A First light receiving element 11, 11A First semiconductor substrate 12 Light receiving area 17 Recess 20, 20A Second light receiving element 21, 21A Second semiconductor substrate 22 Light receiving area 27 Recess 30 Support substrate 31a Support surface

Claims

1. a first light receiving element and a second light receiving element each having a semiconductor substrate including a light receiving region; a support substrate having a support surface that supports the first light receiving element and the second light receiving element; Equipped with the semiconductor substrate on one side of one of the first light receiving element and the second light receiving element further has a main surface including the light receiving region, a back surface opposite to the main surface in a direction perpendicular to the surface, and a recess recessed from the back surface toward the main surface; the semiconductor substrate on the other side of the other of the first light receiving element and the second light receiving element is disposed inside the recess, an angle θ formed between a side surface connecting an opening end of the recess to a bottom surface of the recess and the support surface is 75° or more and 105° or less; Light receiving device.

2. In a cross-sectional view of the light receiving device cut along the direction perpendicular to the surface, when a length of the bottom surface of the recess is W1 and a length between opposing portions of the opening end of the recess is W2, W1 / W2, which is a ratio of W1 to W2, is 0.9 or more and 1.1 or less. The light receiving device according to claim 1 .

3. the other semiconductor substrate has a main surface including the light receiving region, a back surface opposite to the main surface in the direction perpendicular to the surface, and a side surface connecting the main surface and the back surface and facing a side surface of the recess, In a cross-sectional view of the light-receiving device cut along the direction perpendicular to the surface, when a distance between an end portion of the side surface of the semiconductor substrate on the other side on the main surface side and the side surface of the recess is defined as G1, and a distance between an end portion of the side surface of the semiconductor substrate on the other side on the back surface side and the side surface of the recess is defined as G2, G1 / G2, which is the ratio of G1 to G2, is 0.9 or more and 1.1 or less; The light receiving device according to claim 1 .

4. the semiconductor substrate on one side has a first sidewall portion and a second sidewall portion that face each other with the recessed portion therebetween, an angle θ1 between a first side surface of the recess defined by an inner surface of the first side wall portion and the support surface is equal to or greater than 75° and equal to or less than 105°; an angle θ2 between a second side surface of the recess defined by the inner surface of the second side wall portion and the support surface is equal to or greater than 75° and equal to or less than 105°; The light receiving device according to claim 1 .

5. the semiconductor substrate on one side further includes a third sidewall portion connecting one ends of the first sidewall portion and the second sidewall portion, and a fourth sidewall portion connecting the other ends of the first sidewall portion and the second sidewall portion, an angle θ3 between a third side surface of the recess defined by an inner surface of the third side wall portion and the support surface is equal to or greater than 75° and equal to or less than 105°; an angle θ4 formed between a fourth side surface of the recess, which is defined by the inner surface of the fourth side wall portion, and the support surface is equal to or greater than 75° and equal to or less than 105°; The light receiving device according to claim 4 .

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