Semiconductor light emitting device

Abstract

To suppress the decrease in light output of a semiconductor light emitting device.SOLUTION: A semiconductor light emitting device 10 comprises: a package substrate 14; a semiconductor light emitting element 12 bonded onto the package substrate 14; a first encapsulation member 16 containing resin, which covers the semiconductor light emitting element 12 on the package substrate 14, is transparent at the light emitting wavelength of the semiconductor light emitting element 12, and is solid at the operating temperature of the semiconductor light emitting element 12; and a second encapsulation member 18 containing resin, which covers the first encapsulation member, is transparent at the light emitting wavelength of the semiconductor light emitting element 12, is liquid at the operating temperature of the semiconductor light emitting element 12.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] BACKGROUND ART A semiconductor light emitting device is known in which a semiconductor light emitting element bonded onto a package substrate is sealed with silicone resin (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-17427 Summary of the Invention [Problem to be solved by the invention]

[0004] When cracks occur due to deterioration of the silicone resin, the light output decreases.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to provide a technique for suppressing a decrease in the optical output of a semiconductor light-emitting device. [Means for solving the problem]

[0006] A semiconductor light emitting device according to one embodiment of the present invention comprises a package substrate, a semiconductor light emitting element bonded onto the package substrate, a first sealing member covering the semiconductor light emitting element on the package substrate, having translucency at the emission wavelength of the semiconductor light emitting element, being solid at the operating temperature of the semiconductor light emitting element, and containing a resin, and a second sealing member covering the first sealing member, having translucency at the emission wavelength of the semiconductor light emitting element, being liquid at the operating temperature of the semiconductor light emitting element, and containing a resin.

[0007] According to the present invention, it is possible to suppress a decrease in the optical output of a semiconductor light emitting device. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view schematically illustrating a configuration of a semiconductor light emitting device according to a first embodiment. [Figure 2] 1 is a graph showing an example of the time series of light output intensity of semiconductor light emitting devices according to an example and a comparative example. [Figure 3] 4 is a flowchart illustrating an example of a method for manufacturing the semiconductor light emitting device according to the first embodiment. [Figure 4] FIG. 10 is a cross-sectional view schematically illustrating the configuration of a semiconductor light-emitting device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the description, the same elements are designated by the same reference numerals, and redundant explanations will be omitted as appropriate. To facilitate understanding of the description, the dimensional ratios of the components in each drawing do not necessarily correspond to the dimensional ratios of the actual light-emitting element.

[0010] (First embodiment) 1 is a cross-sectional view schematically illustrating the configuration of a semiconductor light emitting device 10 according to the first embodiment. The semiconductor light emitting device 10 includes a semiconductor light emitting element 12, a package substrate 14, a first sealing member 16, and a second sealing member 18.

[0011] The semiconductor light emitting element 12 is a semiconductor light emitting element configured to emit ultraviolet light with a center wavelength λ of approximately 360 nm or less. To output ultraviolet light of such a wavelength, an aluminum gallium nitride (AlGaN)-based semiconductor material with a band gap of approximately 3.4 eV or more is used. In this embodiment, a DUV-LED (Deep Ultraviolet-Light Emitting Diode) chip that emits deep ultraviolet light with a peak emission wavelength λ of 240 nm or more and 320 nm or less is particularly shown.

[0012] The semiconductor light-emitting device 12 includes a translucent substrate 20, a semiconductor layer 22, an anode electrode 24, a cathode electrode 26, and a protective layer 28.

[0013] The translucent substrate 20 is made of a material that is translucent to the ultraviolet light emitted by the semiconductor light-emitting device 12. The light emitted by the semiconductor layer 22 is output from the translucent substrate 20 to the outside of the semiconductor light-emitting device 12. The translucent substrate 20 is made of, for example, sapphire (Al2O3). The translucent substrate 20 has an upper surface 20a, a lower surface 20b, and a side surface 20c. The upper surface 20a and the lower surface 20b are, for example, rectangular. The sizes of the upper surface 20a and the lower surface 20b are not particularly limited, but are, for example, 1 mm square. The thickness of the translucent substrate 20 from the upper surface 20a to the lower surface 20b is, for example, 100 μm or more, 200 μm or more, or 300 μm or more, and is, for example, 1000 μm or less, 700 μm or less, or 500 μm or less.

[0014] The semiconductor layer 22 is provided under the translucent substrate 20 and is provided on the lower surface 20b of the translucent substrate 20. The semiconductor layer 22 includes, for example, an n-type semiconductor layer, an active layer, and a p-type semiconductor layer. The semiconductor layer 22 is made of an AlGaN-based semiconductor material. The AlGaN-based semiconductor material can be represented by the composition of In 1-x-y Al x Ga y N (0 < x + y ≤ 1, 0 < x < 1, 0 < y < 1). The semiconductor layer 22 is covered by the protective layer 28.

[0015] The anode electrode 24 includes a first contact electrode 24a and a first pad electrode 24b. The first contact electrode (24a) is an internal electrode that contacts the semiconductor layer 22 and contacts the p-type semiconductor layer included in the semiconductor layer 22. The first contact electrode 24a is made of, for example, a metal layer such as Rh. The first contact electrode 24a is covered by the protective layer 28. The first pad electrode 24b is an external electrode that is exposed outside the protective layer 28 and is electrically connected to the first contact electrode 24a through an opening provided in the protective layer 28. The first pad electrode 24b is made of a metal layer such as Ni / Au.

[0016] The cathode electrode 26 includes a second contact electrode 26a and a second pad electrode 26b. The second contact electrode 26a is an internal electrode that contacts the semiconductor layer 22 and contacts an n-type semiconductor layer included in the semiconductor layer 22. The second contact electrode 26a is made of a metal layer such as Ti / Al. The second contact electrode 26a is covered with a protective layer 28. The second pad electrode 26b is an external electrode that is exposed to the outside of the protective layer 28 and is electrically connected to the second contact electrode 26a through an opening provided in the protective layer 28. The second pad electrode 26b is made of a metal layer such as Ni / Au.

[0017] The protective layer 28 covers the semiconductor layer 22, the first contact electrode 24a, and the second contact electrode 26a. The protective layer 28 is made of a dielectric material such as an oxide or a nitride, for example, silicon oxide (SiO2), aluminum oxide (Al2O3), silicon nitride (SiN), etc. The protective layer 28 may be made of a stack of multiple protective layers made of different materials.

[0018] The package substrate 14 has a flat plate shape and includes a bonding surface 14a and a back surface 14b. The package substrate 14 includes a first bonding electrode 30 and a second bonding electrode 32 provided on the bonding surface 14a. The package substrate 14 includes a first mounting electrode 34 and a second mounting electrode 36 provided on the back surface 14b. The first bonding electrode 30 is electrically connected to the first mounting electrode 34 inside the package substrate 14. The second bonding electrode 32 is electrically connected to the second mounting electrode 36 inside the package substrate 14. The package substrate 14 is made of, for example, an inorganic material, such as a ceramic material such as alumina (Al2O3), aluminum nitride (AlN), silicon nitride (SiN), or silicon carbide (SiC).

[0019] The semiconductor light emitting element 12 is flip-chip bonded onto the package substrate 14. The semiconductor light emitting element 12 is bonded to a first bonding electrode 30 and a second bonding electrode 32. The semiconductor light emitting element 12 is bonded to the package substrate 14 via a first bonding portion 38 and a second bonding portion 40. The first bonding portion 38 is provided between the anode electrode 24 (first pad electrode 24b) and the first bonding electrode 30, and electrically connects the anode electrode 24 and the first bonding electrode 30. The second bonding portion 40 is provided between the cathode electrode 26 (second pad electrode 26b) and the second bonding electrode 32, and electrically connects the cathode electrode 26 and the second bonding electrode 32.

[0020] The first bonding portion 38 and the second bonding portion 40 are, for example, stud bumps. The first bonding portion 38 and the second bonding portion 40 are formed, for example, by melting the tip of a metal wire such as Au to form a ball and pressing the ball against the first bonding electrode 30 and the second bonding electrode 32. The first bonding portion 38 and the second bonding portion 40 formed on the first bonding electrode 30 and the second bonding electrode 32 are bonded to the anode electrode 24 (first pad electrode 24b) and the cathode electrode 26 (second pad electrode 26b), respectively, by, for example, ultrasonic bonding.

[0021] The first sealing member 16 covers the semiconductor light emitting element 12 on the package substrate 14. The first sealing member 16 is translucent at the emission wavelength of the semiconductor light emitting element 12. The first sealing member 16 has an internal transmittance of 50% or more at the peak emission wavelength of the semiconductor light emitting element 12, and preferably 70% or more, 80% or more, or 90% or more. The first sealing member 16 is solid at the operating temperature of the semiconductor light emitting element 12 (e.g., -10°C or more and 85°C or less). The first sealing member 16 is made of a resin material, for example, a thermosetting or thermoplastic silicone resin. The first sealing member 16 is configured not to contain a phosphor.

[0022] The first sealing member 16 has, for example, an upwardly convex lens shape or a dome shape. The top 16a of the first sealing member 16 is located, for example, above the semiconductor light emitting element 12 that is bonded to the package substrate 14. The first sealing member 16 is formed to cover the entire top surface 12a of the semiconductor light emitting element 12 and to cover the corners that form the outer periphery of the top surface 20a of the light-transmitting substrate 20. The thickness t1 from the top surface 12a of the semiconductor light emitting element 12 to the top 16a of the first sealing member 16 is, for example, 50 μm or more, 100 μm or more, or 200 μm or more, and, for example, 500 μm or less, 400 μm or less, or 300 μm or less.

[0023] The first sealing member 16 contacts the bonding surface 14a of the package substrate 14. The first sealing member 16 covers, for example, the first bonding electrode 30 and the second bonding electrode 32 provided on the bonding surface 14a. The first sealing member 16 is provided so as to cover the entire semiconductor light emitting element 12 on the package substrate 14.

[0024] The second sealing member 18 covers the first sealing member 16. The second sealing member 18 is translucent at the emission wavelength of the semiconductor light emitting element 12. The second sealing member 18 has an internal transmittance of 50% or more, and preferably 70% or more, 80% or more, or 90% or more at the peak emission wavelength of the semiconductor light emitting element 12. The second sealing member 18 is liquid at the operating temperature of the semiconductor light emitting element 12 (for example, -10°C or more and 85°C or less).

[0025] The second sealing member 18 includes a non-curable resin material, such as an uncured silicone-based resin. Here, "uncured" may refer to a state before a curing reaction that forms crosslinks between polymers occurs, or may refer to a state in which the resin does not have a crosslinked structure. The silicone-based resin without a crosslinked portion may be a linear silicone oil or silicone rubber, or a silicone resin with a branched or network structure. The second sealing member 18 may further include a solvent. The second sealing member 18 may include an organic solvent such as an alcohol, ketone, ester, ether, or hydrocarbon solvent. The second sealing member 18 is configured not to include a phosphor.

[0026] The second sealing member 18 may contain the same silicone-based resin as the first sealing member 16. For example, if the first sealing member 16 is a two-component thermosetting silicone-based resin in which a base agent and a curing agent are mixed, the second sealing member 18 may be a silicone-based resin that contains the base agent used in the first sealing member 16 but does not contain a curing agent. By using the same silicone-based resin for the first sealing member 16 and the second sealing member 18, the sealing properties and adhesion of the second sealing member 18 to the first sealing member 16 can be improved.

[0027] The viscosity of the second sealing member 18 is, for example, 1 Pa·s or more, 5 Pa·s or more, or 10 Pa·s or more, and, for example, 1000 Pa·s or less, 100 Pa·s or less, or 50 Pa·s or less. The second sealing member 18 maintains its adherence to the surface of the first sealing member 16 due to the viscosity of the material itself. The thickness t2 of the second sealing member 18 is, for example, 1 μm or more, 5 μm or more, or 10 μm or more, and, for example, 200 μm or less, 100 μm or less, or 50 μm or less. The second sealing member 18 adheres to, for example, the entire surface of the first sealing member 16. The second sealing member 18 contacts, for example, the bonding surface 14a of the package substrate 14.

[0028] 2 is a graph showing an example of the time series of light output intensity of semiconductor light emitting devices according to an example and a comparative example. Graph A shows the time series of light output intensity of semiconductor light emitting device 10 according to the example, which includes both a solid first sealing member 16 and a liquid second sealing member 18. Graph B shows the time series of light output intensity of a semiconductor light emitting device according to a comparative example, which includes a solid first sealing member 16 but does not include a liquid second sealing member 18. In graphs A and B, the light output intensity at the start of lighting is normalized to 1.

[0029] As shown in FIG. 2, graphs A and B have first periods T1a and T1b during which the light output intensity is approximately 1 or greater, and second periods T2a and T2b during which the light output intensity drops below approximately 1 and then drops below 0.7. The first periods T1a and T1b correspond to periods during which no cracks or gaps occur in the first sealing member 16 and the sealing performance of the first sealing member 16 is maintained. The second periods T2a and T2b correspond to periods during which cracks or gaps occur in the first sealing member 16 and the light output intensity decreases depending on the amount of cracks or gaps. The deterioration of the first sealing member 16 is thought to be mainly due to the influence of ultraviolet light emitted from the semiconductor light emitting element 12 and the influence of oxygen and moisture present in the atmosphere surrounding the first sealing member 16.

[0030] As can be seen from FIG. 2 , the first period T1a in the example is longer than the first period T1b in the comparative example, being approximately 1.4 times longer than the first period T1b in the comparative example. Furthermore, the second period T2a in the example is longer than the second period T2b in the comparative example, being approximately 1.25 times longer than the second period T2b in the comparative example. Therefore, the example including the second sealing member 18 can suppress the progression of deterioration of the first sealing member 16 compared to the comparative example not including the second sealing member 18, thereby lengthening the first period until cracks or gaps appear in the first sealing member 16. Furthermore, the example including the second sealing member 18 can suppress the growth and expansion of cracks or gaps even after they appear in the first sealing member 16 compared to the comparative example not including the second sealing member 18, thereby suppressing the rate at which the light output intensity decreases.

[0031] 3 is a flowchart showing an example of a method for manufacturing the semiconductor light emitting device 10 according to the first embodiment. First, the semiconductor light emitting element 12 is bonded onto the package substrate 14 (S10). Next, the semiconductor light emitting element 12 on the package substrate 14 is covered with a thermosetting resin (S12). Next, the thermosetting resin covering the semiconductor light emitting element 12 is heated and cured to form a first sealing member 16 covering the semiconductor light emitting element 12 (S14). Next, the first sealing member 16 is covered with a non-curing resin to form a second sealing member 18 (S16).

[0032] 3 shows a case where a thermosetting resin is used as the first sealing member 16. When a thermoplastic resin is used as the first sealing member 16, instead of the process of S12, the semiconductor light emitting element 12 can be covered with the thermoplastic resin softened by heating. Subsequently, instead of the process of S14, the thermoplastic resin covering the semiconductor light emitting element 12 can be cooled and hardened to form the first sealing member 16 covering the semiconductor light emitting element 12.

[0033] According to this embodiment, by combining the solid first sealing member 16 and the liquid second sealing member 18, it is possible to improve the sealing performance and suppress a decrease in the light output of the semiconductor light emitting device 10 compared to when the liquid second sealing member 18 is not used, thereby improving the lifespan and reliability of the semiconductor light emitting device 10.

[0034] (Second embodiment) 4 is a top view schematically illustrating the configuration of a semiconductor light emitting device 10A according to the second embodiment. The semiconductor light emitting device 10A differs from the first embodiment in that it further includes a frame body 50 provided around the semiconductor light emitting element 12 on the package substrate 14. The following description of the second embodiment will focus on the differences from the first embodiment, and a description of the commonalities will be omitted as appropriate.

[0035] The semiconductor light emitting device 10A includes a semiconductor light emitting element 12, a package substrate 14, a first sealing member 16, a second sealing member 18, and a frame body 50. The semiconductor light emitting element 12, the package substrate 14, the first sealing member 16, and the second sealing member 18 can be configured in the same manner as in the first embodiment.

[0036] The frame body 50 is provided around the semiconductor light emitting element 12 on the package substrate 14. The frame body 50 is provided, for example, along the outer periphery of the package substrate 14, over the entire periphery of the package substrate 14. The frame body 50 may be provided away from the outer periphery of the package substrate 14, or may be provided at a position shifted inward from the outer periphery of the package substrate 14. The frame body 50 is formed, for example, from the same material as the package substrate 14 and molded integrally with the package substrate 14. The frame body 50 may also be formed from a material different from that of the package substrate 14. The frame body 50 may be molded separately from the package substrate 14, or may be bonded to the bonding surface 14a of the package substrate 14 using any bonding material.

[0037] The frame body 50 has an upper surface 50a. The upper surface 50a of the frame body 50 is, for example, a flat surface. The height h2 of the upper surface 50a of the frame body 50 is greater than, for example, the height h1 of the top portion 18a of the second sealing member 18. Note that the height h2 of the upper surface 50a of the frame body 50 may be the same as the height h1 of the top portion 18a of the second sealing member 18, or may be lower than the height h1 of the top portion 18a of the second sealing member 18.

[0038] The first sealing member 16 is provided at a distance from the frame body 50 and does not contact the frame body 50. The second sealing member 18 is provided at a distance from the frame body 50 and does not contact the frame body 50. The second sealing member 18 may be in contact with the frame body 50, or may be provided so as to fill the space between the frame body 50 and the first sealing member 16.

[0039] According to the present embodiment, by providing the frame body 50 on the package substrate 14, the frame body 50 can protect the second sealing member 18. For example, when the viscosity of the second sealing member 18 is low, the frame body 50 can prevent the second sealing member 18 from flowing out. Furthermore, when the second sealing member 18 is provided so as to fill the space between the first sealing member 16 and the frame body 50, the thickness t2 of the second sealing member 18 can be relatively increased, thereby improving the coverage of the first sealing member 16 by the second sealing member 18. This can prevent the first sealing member 16 from peeling off or cracking, thereby improving the reliability of the semiconductor light emitting device 10.

[0040] The present invention has been described above based on the embodiments. It will be understood by those skilled in the art that the present invention is not limited to the above-described embodiments, and that various design changes and modifications are possible, and that such modifications are also within the scope of the present invention.

[0041] Several aspects of the present invention will now be described.

[0042] A first aspect of the present invention is a semiconductor light emitting device comprising: a package substrate; a semiconductor light emitting element bonded onto the package substrate; a first sealing member covering the semiconductor light emitting element on the package substrate, having transparency at the emission wavelength of the semiconductor light emitting element, being solid at the operating temperature of the semiconductor light emitting element, and containing a resin; and a second sealing member covering the first sealing member, having transparency at the emission wavelength, being liquid at the operating temperature, and containing a resin. According to the first aspect, by covering the solid first sealing member containing a resin with the liquid second sealing member containing a resin, deterioration of the first sealing member can be suppressed, and a decrease in the light output of the semiconductor device due to deterioration of the first sealing member can be suppressed.

[0043] A second aspect of the present invention is the semiconductor light emitting device according to the first aspect, wherein the second sealing member includes an uncured silicone resin. According to the second aspect, by using an uncured silicone resin as the second sealing member, deterioration of the first sealing member can be suppressed.

[0044] A third aspect of the present invention is the semiconductor light emitting device according to the first aspect, wherein the second sealing member contains a silicone-based resin and a solvent. According to the third aspect, by using a mixture of a silicone-based resin and a solvent as the second sealing member, deterioration of the first sealing member can be suppressed.

[0045] A fourth aspect of the present invention is the semiconductor light emitting device according to any one of the first to third aspects, wherein the viscosity of the second sealing member is 1 Pa·s or more and 1000 Pa·s or less. According to the fourth aspect, by setting the viscosity of the second sealing member to a predetermined value, it is possible to maintain the state in which the second sealing member adheres to the first sealing member.

[0046] A fifth aspect of the present invention is the semiconductor light emitting device according to any one of the first to fourth aspects, wherein the first sealing member includes a thermosetting silicone resin. According to the fifth aspect, by using a thermosetting silicone resin as the first sealing member, it is possible to improve the sealing performance of the semiconductor light emitting element.

[0047] A sixth aspect of the present invention is the semiconductor light emitting device according to any one of the first to fourth aspects, wherein the first sealing member contains a thermoplastic silicone resin. According to the sixth aspect, by using a thermoplastic silicone resin as the first sealing member, it is possible to improve the sealing performance of the semiconductor light emitting element.

[0048] A seventh aspect of the present invention is the semiconductor light emitting device according to any one of the first to sixth aspects, further comprising a frame body provided around the semiconductor light emitting element on the package substrate, the first sealing member and the second sealing member being provided inside the frame body. According to the seventh aspect, by providing the frame body, it is possible to prevent the second sealing member from leaking out, and to prevent a decrease in coverage by the second sealing member. [Explanation of symbols]

[0049] 10...semiconductor light emitting device, 12...semiconductor light emitting element, 14...package substrate, 16...first sealing member, 18...second sealing member, 50...frame body.

Claims

1. A package substrate; a semiconductor light emitting element bonded onto the package substrate; a first sealing member that covers the semiconductor light emitting element on the package substrate, that is translucent at an emission wavelength of the semiconductor light emitting element, that is solid at an operating temperature of the semiconductor light emitting element, and that contains a resin; a second sealing member that covers the first sealing member, that is translucent at the emission wavelength, that is liquid at the operating temperature, and that contains a resin; Semiconductor light-emitting device.

2. the second sealing member contains an uncured silicone-based resin; The semiconductor light emitting device according to claim 1 .

3. the second sealing member contains a silicone-based resin and a solvent; The semiconductor light emitting device according to claim 1 .

4. The viscosity of the second sealing member is 1 Pa·s or more and 1000 Pa·s or less. The semiconductor light emitting device according to claim 1 .

5. the first sealing member contains a thermosetting silicone resin; The semiconductor light emitting device according to claim 1 .

6. the first sealing member contains a thermoplastic silicone-based resin; The semiconductor light emitting device according to claim 1 .

7. a frame body provided around the semiconductor light emitting element on the package substrate; the first sealing member and the second sealing member are provided inside the frame body; The semiconductor light emitting device according to claim 1 .

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