Semiconductor device

Abstract

A semiconductor device (10) according to the present invention comprises: a support substrate (131); a layer structure having an active layer (133) and disposed on the support substrate; a p-type semiconductor layer (135) disposed on one lateral surface of the layer structure; an n-type semiconductor layer (136) disposed on the other lateral surface of the layer structure; a p-type electrode (137) disposed on part of the surface of the p-type semiconductor layer on the opposite side from the support substrate; an n-type electrode (138) disposed on part of the surface of the n-type semiconductor layer on the opposite side from the support substrate; cladding (139) disposed between the p-type and n-type electrodes; a thermal interface material (14) which is disposed on the surface of the cladding on the opposite side from the support substrate and which has a thermal conductivity higher than the thermal conductivity of SiO2; and a heatsink (11) disposed on the opposite side from the support substrate, with the layer structure in between.　With this configuration, the present invention can provide a semiconductor device with excellent heat dissipation.

Description

semiconductor devices

[0001] The present invention relates to a semiconductor device with excellent heat dissipation properties.

[0002] With the spread of devices and technologies such as smartphones, cloud computing, and IoT, internet traffic is steadily increasing year by year. To keep up with this, there is a need for smaller, faster, and less power-consuming optical transmitters used in data centers.

[0003] As the optical transmitter, an externally modulated laser in which a semiconductor laser and an external modulator are integrated, or a directly modulated laser in which the optical output is directly modulated by modulating the injection current is used.

[0004] To extend the transmission distance, both externally modulated and directly modulated lasers need to have higher optical output power. To achieve higher speeds, directly modulated lasers need to increase the relaxation oscillation frequency and widen the modulation bandwidth.

[0005] In order to increase the optical output power and relaxation oscillation frequency, it is necessary to increase the amount of current injected into a semiconductor laser. Generally, heat generated by current injection reduces the material gain and increases the threshold carrier density, resulting in saturation of the optical output power and relaxation oscillation frequency. Therefore, reducing the device thermal resistance is important for improving the performance of semiconductor lasers.

[0006] Therefore, it has been demonstrated that a membrane laser on a high heat dissipation substrate can improve its performance (Non-Patent Document 2). In detail, by using a SiC substrate, which has a refractive index of about 2.6 at a wavelength of 1.3 μm, as a support substrate for the membrane laser, the SiO ２ / The heat dissipation performance can be improved while maintaining high optical confinement in the membrane laser on the Si substrate, and a relaxation oscillation frequency of 42 GHz has been achieved.

[0007] The heat dissipation path of the laser structure described above is mainly through the path in which heat generated in the diode when current is injected flows to the support substrate grounded to the heat sink. Therefore, if the thermal conductivity of the support substrate is low, heat is not efficiently dissipated from the heat source.

[0008] On the other hand, in flip-chip mounting, the semiconductor chip is flipped over and connected to a mounting substrate with a heat sink via solder or plating. Since the support substrate is placed on the opposite side of the heat sink across the semiconductor chip, it is thought that heat is efficiently dissipated via the electrodes of the semiconductor chip placed on the heat sink side.

[0009] Hidetaka Nishi, Takuro Fujii, Koji Takeda, Koichi Hasebe, Takaaki Kakitsuka, Tai Tsuchizawa, Tsuyoshi Yamamoto, Koji Yamada, and Shinji Matsuo, "Membrane distributed-reflector laser integrated with SiOx-based spot-size converter on Si substrate," Opt. Express 24, 18346-18352 (2016). S. Yamaoka, N. -P. Diamantopoulos, H. Nishi, R. Nakao, T. Fujii, K. Takeda, T. Hiraki, T. Tsurugaya, S. Kanazawa, H. Tanobe, T. Kakitsuka, T. Tsuchizawa, F. Koyama, and S. Matsuo, "Directly modulated membrane lasers with 108 GHz bandwidth on a high-thermal-conductivity silicon carbide substrate," Nature Photonics volume 15, pages 28-35 (2021).

[0010] However, in the vicinity of the electrodes of a semiconductor chip (particularly a semiconductor optical device), air or cladding (e.g., SiO ２ ) exist, there is a problem that heat cannot be efficiently dissipated from the heat source via the electrodes.

[0011] In order to solve the above-mentioned problems, a semiconductor device according to the present invention includes a support substrate, a layer structure having an active layer disposed on the support substrate, a p-type semiconductor layer disposed on one side of the layer structure, an n-type semiconductor layer disposed on the other side of the layer structure, a p-type electrode disposed on a part of a surface of the p-type semiconductor layer opposite to the support substrate, an n-type electrode disposed on a part of a surface of the n-type semiconductor layer opposite to the support substrate, a cladding disposed between the p-type electrode and the n-type electrode, and a SiO ２ and a heat sink disposed on the opposite side of the layer structure from the support substrate, with the layer structure sandwiched between the heat dissipation material and the support substrate.

[0012] According to the present invention, a semiconductor device with excellent heat dissipation properties can be provided.

[0013] FIG. 1 is a schematic cross-sectional view showing the configuration of a semiconductor device according to a first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing an example of the configuration of a semiconductor device according to the first embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing the configuration of a conventional semiconductor device. FIG. 4 is a schematic cross-sectional view showing the configuration of a conventional semiconductor device. FIG. 5 is a diagram for explaining the effects of the semiconductor device according to the first embodiment of the present invention. FIG. 6 is a diagram for explaining the effects of the semiconductor device according to the first embodiment of the present invention. FIG. 7 is a diagram for explaining the effects of the semiconductor device according to the first embodiment of the present invention. FIG. 8 is a diagram for explaining the effects of the semiconductor device according to the first embodiment of the present invention. FIG. 9 is a diagram for explaining the effects of the semiconductor device according to the first embodiment of the present invention. FIG. 10 is a diagram for explaining the effects of the semiconductor device according to the first embodiment of the present invention. FIG. 11 is a diagram for explaining the effects of the semiconductor device according to the first embodiment of the present invention. FIG. 12 is a schematic cross-sectional view showing the configuration of a semiconductor device according to a second embodiment of the present invention. FIG. 13 is a schematic cross-sectional view showing the configuration of a semiconductor device according to a third embodiment of the present invention. FIG. 14 is a schematic cross-sectional view showing an example of the configuration of a semiconductor device according to the third embodiment of the present invention.

[0014] First Embodiment A semiconductor device according to a first embodiment of the present invention will be described with reference to FIGS.

[0015] <Configuration of Semiconductor Device> The semiconductor device 10 according to this embodiment has a configuration in which a semiconductor laser is flip-chip mounted, and as shown in FIG. 1, includes a heat sink 11, a heat dissipating substrate 12, a semiconductor laser 13, and a heat dissipating material 14.

[0016] The semiconductor laser 13 is a laser with a membrane structure, and includes a support substrate 131 on the front surface side of the semiconductor device 10 (opposite the heat sink 11 ), and a lateral pin structure below the support substrate 131 .

[0017] In detail, the device has a layer structure made up of an i (intrinsic) type semiconductor layer 132, an active layer 133, and an i-type semiconductor layer 134, with a p-type semiconductor 135 on one side of the layer structure and an n-type semiconductor 136 on the other side. A p-type electrode 137 and an n-type electrode 138 are provided on the lower surfaces (the surfaces opposite to the support substrate 131) of the p-type semiconductor 135 and the n-type semiconductor 136, respectively, and a cladding 139 is provided between the p-type electrode 137 and the n-type electrode 138.

[0018] As an example of the layer structure, the active layer 133 has an InGaAsP-based multiple quantum well structure for the 1.55 μm wavelength band, with six quantum well layers. The active layer 133 has a thickness of 150 nm. Each i-layer is made of undoped InP and is 50 nm thick.

[0019] The p-type semiconductor 135 is, for example, Zn-doped (1×10 １８ cm －３ ) p-type InP. The n-type semiconductor 136 is, for example, Si-doped (2×10 １８ cm －３ ) n-type InP.

[0020] The cladding 139 is made of, for example, SiO ２ and its thickness is about 100 nm.

[0021] In the semiconductor device 10 , a heat dissipation material 14 is provided between the clad 139 of the semiconductor laser 13 and the heat dissipation substrate 12 in the vicinity of the electrodes 137 , 138 .

[0022] The heat dissipating material 14 is, for example, Al ２ O ３ The heat dissipating material 14 may be other materials such as SiC, GaN, diamond, etc. The thermal conductivity of the heat dissipating material 14 is SiO ２ When the heat dissipating material 14 is disposed in close proximity to the semiconductor core, it is desirable that the material be a low refractive index material to ensure optical confinement.

[0023] The heat dissipation substrate 12 is, for example, a SiC substrate. ２ O ３ The heat dissipation substrate 12 may be made of other materials such as SiO. ２ It is desirable that the thermal conductivity is higher than that of the

[0024] The support substrate 131 is made of, for example, SiO ２ The support substrate 131 is made of Si, SiO ２ / Si, SiC, GaN, AlN, diamond, etc. may also be used.

[0025] In the present embodiment, an example in which the semiconductor device includes a heat dissipation substrate has been described, but the present invention is not limited to this, and as shown in FIG. 2, the semiconductor device may not include a heat dissipation substrate.

[0026] <Effects> The effects of the semiconductor device 10 according to this embodiment will be described with reference to FIGS.

[0027] 3 and 4 show the configurations of conventional semiconductor devices 20 and 30 for comparison with the semiconductor device 10 according to this embodiment.

[0028] 3 shows the configuration of a semiconductor device 20 in which a support substrate 131 of the semiconductor laser 13 is disposed on the heat sink 11 side. The semiconductor device 20 includes the semiconductor laser 13 on the heat sink 11, and the Si(131_1) / SiO ２(131_2) The support substrate 131 is disposed so as to be in contact with the heat sink 11. The semiconductor laser 13 has a horizontal pin structure, as in the present embodiment. In the conventional semiconductor device 20, the semiconductor laser 13 may have a vertical pin structure. The cladding (SiO ２ ) 139 has a thickness of 100 nm.

[0029] In addition, in the manufacture of the semiconductor device 20, as an example, the support substrate 131 and the InP substrate may be formed by surface activated bonding or the like.

[0030] 4 shows the configuration of a flip-chip mounted semiconductor device 30. In the semiconductor device 30, a support substrate 131 of the semiconductor laser 13 is placed on the opposite side of the heat sink 11. Electrodes 137 and 138 are connected to the heat sink 11, and there is a space (air) between the clad 139 and the heat sink 11.

[0031] 5 shows the calculation results of the temperature rise distribution in the cross section of the conventional semiconductor device 20 shown in FIG. ２ Because the thermal conductivity of p-InP 135 is low, the heat in p-InP 135 is not efficiently dissipated to the heat sink 11. Therefore, the temperature rise in the semiconductor device 20 was calculated using the finite element method, assuming that a 100 mW heat source is present in the p-InP region (135). The element length (length perpendicular to the paper surface) of the semiconductor device 20 was set to 50 μm.

[0032] 5 to 11, the amount of temperature rise is large in the areas displayed in white, and the amount of temperature rise decreases as the color becomes darker.

[0033] The thermal resistance in the active layer 133 was calculated based on the temperature rise distribution. The thermal resistance was calculated by dividing the average temperature rise in the active layer 133 obtained from the temperature rise distribution by the power (100 mW) of the heat source. For example, in FIG. 5, the average temperature rise in the active layer 133 is obtained as 1204 K / W. The relaxation oscillation frequency at this time is calculated to be 20 GHz based on the rate equation.

[0034] 6 shows the calculation results of the temperature rise distribution in the conventional flip-chip mounted semiconductor device 30 shown in FIG. 4. The temperature rise in the p-InP region (135) where the heat source is set is about 90 K, and the temperature rise in the active layer 133 is about 30 K to 50 K. The thermal resistance of the active layer 133 at this time is 474 K / W. In this way, in the flip-chip mounted semiconductor device 30, heat is efficiently dissipated to the heat sink 11 via the electrodes 137 and 138, reducing the thermal resistance of the active layer 133 and the temperature rise.

[0035] 7 shows the calculation results of the temperature rise distribution in the flip-chip mounted semiconductor device 10_2 according to the present embodiment shown in FIG. ２ O ３ The thickness of the electrodes 137, 138 and the heat dissipating material 14 was set to about 1 μm.

[0036] The temperature rise in the p-InP region (135) where the heat source is set is about 50 K, and the temperature rise in the active layer 133 is about 20 to 30 K. The thermal resistance in the active layer 133 at this time is 261 K / W.

[0037] In this way, in the flip-chip mounted semiconductor device 10_2, the heat dissipation material (Al ２ O ３ Heat is efficiently dissipated to the heat sink 11 via the heat sink 14, and the thermal resistance of the active layer 133 can be significantly reduced compared to conventional semiconductor devices, thereby reducing the temperature rise.

[0038] Similarly, in this configuration, when the thickness of the electrodes 137, 138 and the heat dissipating material 14 was set to about 2 μm, the thermal resistance was 282 K / W.

[0039] In the lateral pin structure of the semiconductor device 10_2, the distance from the active layer 133 to the heat source or electrodes (pads) 137, 138 is short at about 100 nm, so by making the electrodes (pads) 137, 138 thin, the distance between the heat source and the heat sink 11 can be shortened, allowing for efficient heat dissipation.

[0040] FIG. 8 shows the heat dissipation material (Al ２O ３ 1 shows the calculation results of the temperature rise distribution when there is a gap (air) between the substrate 14 and the heat sink 11. The thickness of the gap is set to 100 nm.

[0041] The temperature rise in the p-InP region (135) where the heat source is set is about 50 K, and the temperature rise in the active layer 133 is about 20 to 30 K. The thermal resistance in the active layer 133 at this time is 309 K / W.

[0042] In this way, in the flip-chip mounted semiconductor device 10_2, the heat dissipation material (Al ２ O ３ Even if there is a gap (air) between the heat sink 11 and the heat dissipation material (Al ２ O ３ Heat is efficiently dissipated to the heat sink 11 via the heat sink 14, and the thermal resistance of the active layer 133 can be significantly reduced compared to conventional semiconductor devices, thereby reducing the temperature rise.

[0043] FIG. 9 shows a conventional semiconductor device (FIG. 3) having a SiO ２ This shows the temperature rise distribution when an overclad (8 μm thick) 15 is provided. This configuration is, for example, a configuration in which a spot size converter (SSC) is provided in the overclad 15 in the waveguide direction (direction perpendicular to the paper surface).

[0044] The temperature rise in the p-InP region (135) where the heat source is set is about 150 K, and the temperature rise in the active layer 133 is about 100 K to 130 K. At this time, the thermal resistance in the active layer 133 is 1173 K / W. This thermal resistance value is calculated by dividing the heat from the heat source (p-InP region 135) by the SiO ２ Since heat is dissipated through the overclad 15, the thermal resistance value is lower than that in FIG.

[0045] 10 shows the temperature rise distribution of a semiconductor device in which the semiconductor laser 13 in FIG. 9 is flip-mounted. In detail, the upper and lower surfaces of the semiconductor laser 13 are inverted, and the ends of the electrodes (Au) 137 and 138 are fixed to SiO ２The semiconductor laser 13 is connected to the heat sink 11 via a SiO 16 (thickness: about 1 μm). The thickness of the end portions of the electrodes (Au) 137 and 138 is 13 μm, and the width is about 1 μm. ２ There is a space (air) between SiO ２ SiO on the overclad 15 and heat sink 11 ２ The distance between them is about 5 μm.

[0046] The thermal resistance of the active layer 133 is 691 K / W. This thermal resistance value is lower than the thermal resistance value in FIG.

[0047] 11 shows a temperature rise distribution in an example of the semiconductor device according to the present embodiment. In this example of the semiconductor device, the semiconductor laser 13 and the SiO 2 on the heat sink 11 in the semiconductor device shown in FIG. ２ The space between the ２ O ３ is filled.

[0048] The thermal resistance of the active layer 133 is 672 K / W. In this way, the heat of the heat source (p-InP region 135) is transferred to the heat dissipation material (Al ２ O ３ Since heat is dissipated through the heat generating element 14, the thermal resistance can be reduced.

[0049] In this configuration, when the thickness of the electrodes 137 and 138 is 9 μm, the thermal resistance of the active layer 133 is 676 K / W.

[0050] As described above, the semiconductor device according to this embodiment has a thin-film lateral pin structure, and therefore the heat source can be placed near the heat sink 11, thereby enabling efficient heat dissipation.

[0051] Second Embodiment A semiconductor device according to a second embodiment of the present invention will be described with reference to FIG.

[0052] <Configuration of Semiconductor Device> As shown in FIG. 12, a semiconductor device 40 according to this embodiment includes a heat sink 11 and a semiconductor laser 13, similar to the first embodiment.

[0053] Furthermore, the semiconductor device 40 has a groove structure 41 on the surface of the support substrate 131 of the semiconductor laser 13 .

[0054] This increases the surface area of ​​the semiconductor device 40, thereby improving heat dissipation.

[0055] The semiconductor device 40 may include a heat dissipation substrate 12 between the heat sink 11 and the semiconductor laser 13 .

[0056] Third Embodiment A semiconductor device according to a third embodiment of the present invention will be described with reference to FIGS.

[0057] <Configuration of Semiconductor Device> As shown in FIG. 13, a semiconductor device 50 according to this embodiment includes a heat sink 11 and a semiconductor laser 13, similar to the first embodiment.

[0058] Furthermore, the semiconductor device 50 includes a second heat dissipation material 51 on the surface of the support substrate 131 of the semiconductor laser 13. The second heat dissipation material 51 may be disposed after thinning the support substrate 131, or may be disposed without thinning the support substrate 131.

[0059] This provides the second heat dissipation material 51 on the support substrate 131, thereby improving heat dissipation.

[0060] 14, a semiconductor device 50_2 as an example of the semiconductor device according to the present embodiment may have a groove structure 52 formed on the surface of a support substrate 131 of a semiconductor laser 13. This increases the surface area of ​​the semiconductor device 50_2, thereby improving heat dissipation.

[0061] In the semiconductor device according to this embodiment, a heat dissipation substrate 12 may be provided between the heat sink 11 and the semiconductor laser 13 .

[0062] In the embodiment of the present invention, an example has been shown in which an InGaAsP-based multiple quantum well structure for the 1.55 μm wavelength band is used for the active layer of the semiconductor laser 13, but this is not limiting. Other wavelength bands such as the 1.3 μm wavelength band may also be used, and other materials such as AlGaAs, GaAs, and GaN may also be used.

[0063] In the embodiment of the present invention, an example using a semiconductor laser has been shown, but a semiconductor element other than a semiconductor laser may also be used. In the case of an optical device such as a semiconductor laser, a cladding is provided, but in the case of a device other than an optical device, a cladding may not be provided.

[0064] In the embodiments of the present invention, examples of the structure, dimensions, materials, etc. of each component in the configuration of the semiconductor device, manufacturing method, etc. are shown, but the present invention is not limited to these examples. Anything that can exhibit the functions and effects of the semiconductor device can be used.

[0065] It should be noted that the present invention is not limited to the above-described embodiments, and it is clear that many modifications and combinations can be made by a person having ordinary knowledge in the art within the technical concept of the present invention.

[0066] A part or all of the above-described embodiment or an example thereof can be described as, but is not limited to, the following supplementary notes.

[0067] (Supplementary Note 1) A semiconductor device comprising: a support substrate; a layer structure having an active layer disposed on the support substrate; a p-type semiconductor layer disposed on one side of the layer structure; an n-type semiconductor layer disposed on the other side of the layer structure; a p-type electrode disposed on a part of a surface of the p-type semiconductor layer opposite to the support substrate; an n-type electrode disposed on a part of a surface of the n-type semiconductor layer opposite to the support substrate; a clad disposed between the p-type electrode and the n-type electrode; and a clad disposed on a surface of the clad opposite to the support substrate, the clad being made of SiO ２ a heat dissipation material having a thermal conductivity higher than that of the support substrate; and a heat sink disposed on the opposite side of the layer structure from the support substrate.

[0068] (Note 2) Between the heat dissipation material and the heat sink, SiO ２10. The semiconductor device of claim 1, further comprising a heat dissipation substrate having a thermal conductivity greater than that of the semiconductor device.

[0069] (Supplementary Note 3) The semiconductor device described in Supplementary Note 1 or Supplementary Note 2, further comprising a cladding between the layer structure and the heat dissipation material.

[0070] (Appendix 4) The semiconductor device according to appendix 3, wherein the cladding has a thickness of about 8 μm.

[0071] (Supplementary Note 5) The semiconductor device according to any one of Supplementary Notes 1 to 4, further comprising a groove structure on the surface of the support substrate.

[0072] (Supplementary Note 6) A semiconductor device according to any one of Supplementary Notes 1 to 4, further comprising a second heat dissipation material on the surface of the support substrate.

[0073] (Supplementary Note 7) The semiconductor device described in Supplementary Note 6, further comprising a groove structure on the surface of the second heat dissipation material.

[0074] The present invention relates to a semiconductor device, and can be applied to an optical transmission system or a semiconductor device for an optical transmission system.

[0075] REFERENCE SIGNS LIST 10 Semiconductor device 11 Heat sink 131 Support substrate 133 Active layer 135 P-type semiconductor layer 136 N-type semiconductor layer 137 P-type electrode 138 N-type electrode 139 Cladding 14 Heat dissipation material

Claims

1. A support substrate; a layer structure having an active layer disposed on the support substrate; a p-type semiconductor layer disposed on one side of the layer structure; an n-type semiconductor layer disposed on the other side of the layer structure; a p-type electrode disposed on a portion of a surface of the p-type semiconductor layer opposite to the support substrate; an n-type electrode disposed on a portion of a surface of the n-type semiconductor layer opposite to the support substrate; a cladding disposed between the p-type electrode and the n-type electrode; and a cladding disposed on a surface of the cladding opposite to the support substrate, the cladding being made of SiO. ２ a heat dissipation material having a thermal conductivity higher than that of the support substrate; and a heat sink disposed on the opposite side of the layer structure to the support substrate.

2. Between the heat dissipation material and the heat sink, SiO ２ 13. The semiconductor device of claim 1, further comprising a heat dissipating substrate having a thermal conductivity greater than that of the semiconductor device.

3. The semiconductor device of claim 1, further comprising a cladding between said layer structure and said heat dissipating material.

4. The semiconductor device of claim 3, wherein the cladding has a thickness of about 8 μm.

5. The semiconductor device of claim 1, further comprising a groove structure on a surface of said supporting substrate.

6. The semiconductor device of claim 1, further comprising a second heat dissipation material on a surface of said support substrate.

7. The semiconductor device of claim 6, further comprising a groove structure on a surface of said second heat dissipating material.

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