Semiconductor light-emitting device

Abstract

To improve a light output and reliability of a semiconductor light-emitting device.SOLUTION: A semiconductor light-emitting device 10 comprises: a package substrate 14; a semiconductor light-emitting element 12 that is bonded in a flip-chip onto the package substrate 14; and a sealing member 16 that covers the semiconductor light-emitting element 12 on the package substrate 14, and includes a light transmissivity in a light-emission wavelength of the semiconductor light-emitting element 12. The semiconductor light-emitting element 12 comprises: an anode electrode 24 and a cathode electrode 26 that are bonded to the package substrate 14; a semiconductor layer 22 on the anode electrode 24 and the cathode electrode 26; and a light transmissivity substrate 20 on the semiconductor layer 22. The light transmissivity substrate 20 includes: an upper surface 20a contacted to the sealing member 16; and a side surface 20c contacted to the sealing member 16 between the upper surface 20a and the semiconductor layer 22. An area of the side surface 20c is an area of the upper surface 20a or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] There is known a semiconductor light emitting device in which a semiconductor light emitting element bonded onto a package substrate is sealed with resin. For example, a technology has been proposed to improve the light extraction efficiency by forming the sealing resin into a dome shape that is convex upward (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-59754 A Summary of the Invention [Problem to be solved by the invention]

[0004] When the sealing member is formed in a dome shape, it is necessary to increase the thickness of the sealing member located above the semiconductor light emitting element. If the amount of the sealing member is increased to make the sealing member thicker, distortion caused by the difference in material between the sealing member and the semiconductor light emitting element increases, and the sealing member becomes more likely to peel off or crack.

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

[0006] A semiconductor light emitting device according to an embodiment of the present invention includes a package substrate, a semiconductor light emitting element flip-chip bonded onto the package substrate, and a sealing member that covers the semiconductor light emitting element on the package substrate and is translucent at the emission wavelength of the semiconductor light emitting element. The semiconductor light emitting element includes an anode electrode and a cathode electrode bonded to the package substrate, a semiconductor layer on the anode electrode and the cathode electrode, and a translucent substrate on the semiconductor layer. The translucent substrate has an upper surface in contact with the sealing member and a side surface between the upper surface and the semiconductor layer in contact with the sealing member, the area of ​​the side surface being equal to or less than the area of ​​the upper surface. Effect of the Invention

[0007] According to the present invention, the optical output and reliability of a semiconductor light emitting device can be improved. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view illustrating a schematic configuration of a semiconductor light emitting device according to an embodiment. [Diagram 2] 1 is a top view illustrating a schematic configuration of a semiconductor light emitting device according to an embodiment. [Diagram 3] 11 is a table showing the optical output and sealing performance of a semiconductor light emitting device when the thickness of a light-transmitting substrate is changed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. In the description, the same elements are given the same reference numerals, and duplicated descriptions will be omitted as appropriate. In addition, in order to facilitate understanding of the description, the dimensional ratios of the components in each drawing do not necessarily match the dimensional ratios of the actual light-emitting element.

[0010] 1 is a cross-sectional view showing a schematic configuration of a semiconductor light emitting device 10 according to the embodiment. The semiconductor light emitting device 10 includes a semiconductor light emitting element 12, a package substrate 14, and a sealing member 16.

[0011] The semiconductor light-emitting element 12 is a semiconductor light-emitting element configured to emit ultraviolet light with a central wavelength λ of about 360 nm or less. In order to output ultraviolet light of such a wavelength, an aluminum gallium nitride (AlGaN) - based semiconductor material with a bandgap of about 3.4 eV or more is used. In this embodiment, in particular, a DUV - LED (Deep UltraViolet - Light Emitting Diode) chip that emits deep ultraviolet light with a central wavelength λ of about 240 nm to 320 nm will be described.

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

[0013] The light - transmissive substrate 20 is made of a material that is light - transmissive to the ultraviolet light emitted by the semiconductor light - emitting element 12. The light emitted by the semiconductor layer 22 is output from the light - transmissive substrate 20 to the outside of the semiconductor light - emitting element 12. The light - transmissive substrate 20 is composed of, for example, sapphire (Al 2 O 3 ) or single - crystal aluminum nitride (AlN). The light - transmissive 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 t from the upper surface 20a to the lower surface 20b of the light - transmissive substrate 20 is, for example, 50 μm or more, 100 μm or more, or 150 μm or more, and is, for example, 300 μm or less, 250 μm or less, or 200 μm or less.

[0014] The semiconductor layer 22 is provided under the light - transmissive substrate 20 and is provided on the lower surface 20b of the light - transmissive 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 composed 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 in contact with the semiconductor layer 22, and is in contact with a p-type semiconductor layer included in the semiconductor layer 22. The first contact electrode 24a is made of a metal layer such as Rh. The first contact electrode 24a is covered with a protective layer 28. The first pad electrode 24b is an external electrode exposed to the outside of 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 in contact with the semiconductor layer 22, and is in contact with 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 by a protective layer 28. The second pad electrode 26b is an external electrode 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, and is, for example, silicon oxide (SiO 2 ), aluminum oxide (Al 2 O 3 ), silicon nitride (SiN), etc. The protective layer 28 may be made of a laminate of multiple protective layers made of different materials.

[0018] The package substrate 14 has a flat plate shape and has a bonding surface 14a and a back surface 14b. The package substrate 14 has a first bonding electrode 30 and a second bonding electrode 32 provided on the bonding surface 14a. The package substrate 14 has 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 alumina (Al 2 O 3 ), aluminum nitride (AlN), silicon nitride (SiN), silicon carbide (SiC), and other ceramic materials.

[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 shape, and pressing the ball against the first bonding electrode 30 and the second bonding electrode 32, respectively. 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] In a state in which the semiconductor light emitting element 12 is bonded to the package substrate 14, the height hb from the package substrate 14 (bonding surface 14a) to the lower surface 20b of the light-transmitting substrate 20 is, for example, smaller than the thickness t of the light-transmitting substrate 20. The height hb from the package substrate 14 to the lower surface 20b of the light-transmitting substrate 20 is, for example, 200 μm or less, 100 μm or less, 50 μm or less, or 30 μm or less. The height hb from the package substrate 14 to the lower surface 20b of the light-transmitting substrate 20 is, for example, 10 μm or more, 15 μm or more, 20 μm or more, or 25 μm or more.

[0022] When the semiconductor light emitting element 12 is bonded to the package substrate 14, the height ha from the package substrate 14 (bonding surface 14a) to the upper surface 12a of the semiconductor light emitting element 12 (upper surface 20a of the light-transmitting substrate 20) is, for example, 100 μm or more, 200 μm or more, or 250 μm or more. The height ha from the package substrate 14 to the upper surface 12a of the semiconductor light emitting element 12 is, for example, 500 μm or less, 400 μm or less, or 300 μm or less.

[0023] The sealing member 16 covers the semiconductor light emitting element 12 on the package substrate 14. The sealing member 16 is formed, for example, over the entire bonding surface 14a of the package substrate 14. The sealing member 16 contacts the bonding surface 14a of the package substrate 14 and contacts the first bonding electrode 30 and the second bonding electrode 32. The sealing member 16 contacts the side surface 20c and the top surface 20a of the light-transmitting substrate 20. The sealing member 16 is made of a material having light transmissivity at the emission wavelength of the semiconductor light emitting element 12. The sealing member 16 has an internal transmittance of 50% or more at the peak emission wavelength of the semiconductor light emitting element 12, and is preferably 70% or more, 80% or more, or 90% or more. The sealing member 16 is made of a material having a lower refractive index than the light-transmitting substrate 20. The sealing member 16 is made of, for example, a silicone resin or a fluororesin. The sealing member 16 may be made of an inorganic material such as quartz or a glass material instead of a resin. The sealing member 16 is configured so as not to contain, for example, a phosphor.

[0024] The sealing member 16 has, for example, a lens shape or a dome shape that is convex upward. The top 42 of the sealing member 16 is located at the top of the semiconductor light emitting element 12 that is bonded to, for example, the package substrate 14. The sealing member 16 is formed so as to cover the entire upper surface 12a of the semiconductor light emitting element 12. The height hc from the upper surface 12a of the semiconductor light emitting element 12 to the top 42 of the sealing member 16 is, for example, 100 μm or more, 150 μm or more, or 200 μm or more. The height hc from the upper surface 12a of the semiconductor light emitting element 12 to the top 42 of the sealing member 16 is, for example, 500 μm or less, 400 μm or less, or 300 μm or less. The height hc from the upper surface 12a of the semiconductor light emitting element 12 to the top 42 of the sealing member 16 is, for example, smaller than the height ha of the semiconductor light emitting element 12. The height hc from the upper surface 12a of the semiconductor light-emitting element 12 to the top 42 of the sealing member 16 may be, for example, approximately the same as the thickness t of the light-transmitting substrate 20, or may be 0.5 to 2 times the thickness t of the light-transmitting substrate 20.

[0025] 2 is a top view showing a schematic configuration of a semiconductor light emitting device 10 according to an embodiment. The semiconductor light emitting device 10 further includes a protective element 50. The protective element 50 is a diode, such as a Zener diode, that protects the semiconductor light emitting element 12 from surge currents and static electricity. The protective element 50 is bonded to a bonding surface 14a of a package substrate 14. The protective element 50 is bonded to, for example, a first bonding electrode 30 and a second bonding electrode 32, and is connected in parallel to the semiconductor light emitting element 12. An upper surface 50a of the protective element 50 is covered by a sealing member 16.

[0026] The upper surface 12a of the semiconductor light emitting element 12 (the upper surface 20a of the light-transmitting substrate 20) has a plurality of sides 44a, 44b, 44c, and 44d. In the example of Fig. 2, the upper surface 12a of the semiconductor light emitting element 12 is rectangular and has four sides 44a to 44d. The upper surface 12a of the semiconductor light emitting element 12 may have a polygonal shape other than a quadrangle, such as a triangle, a hexagon, or an octagon, instead of a rectangle.

[0027] The light-transmitting substrate 20 is preferably configured so that the area Sc of the side surface 20c is equal to or smaller than the area Sa of the upper surface 20a. As shown in FIG. 2, when the upper surface 20a of the light-transmitting substrate 20 is a square, the length of one side 44a is L, and the thickness of the light-transmitting substrate 20 is t, the area Sa of the upper surface 20a is L. 2 and the area of ​​the side surface 20c is Sc=4Lt. Here, the condition for Sa≧Sc can be expressed as L≧4t. When the length L of one side 44a of the light-transmitting substrate 20 is 1 mm, the thickness t of the light-transmitting substrate 20 is preferably 250 μm or less. By making the area Sc of the side surface 20c of the light-transmitting substrate 20 relatively small, peeling or cracking of the sealing member 16 in contact with the side surface 20c can be suppressed.

[0028] FIG. 3 is a table showing the optical output and sealing performance of the semiconductor light emitting device 10 when the thickness t of the light-transmitting substrate 20 is changed. In Comparative Examples 1 to 3, the thickness t of the light-transmitting substrate 20 is set to 100 μm, 200 μm, and 430 μm when the sealing member 16 is not provided. In Examples 1 to 7, the thickness t of the light-transmitting substrate 20 is set to 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, and 450 μm when the sealing member 16 is provided. The side surface ratio (Sc / Sa) is the area Sc of the side surface 20c when the area Sa of the upper surface 20a of the light-transmitting substrate 20 is used as a reference. In the Comparative Examples and Examples, the material of the light-transmitting substrate 20 is sapphire, the material of the sealing member 16 is silicone resin, and the area Sa of the upper surface 20a of the light-transmitting substrate 20 is 1 mm 2 (=1mm×1mm).

[0029] As shown in Fig. 3, in both the comparative example and the example, the light output improves as the thickness t of the light-transmitting substrate 20 increases, that is, as the side surface ratio (Sc / Sa) increases. This is believed to be because the amount of ultraviolet light extracted to the outside from the light-transmitting substrate 20 increases as the area Sc of the side surface 20c of the light-transmitting substrate 20 increases. In Fig. 3, the light output of Comparative Example 3, in which the sealing member 16 is not provided and the thickness t of the light-transmitting substrate 20 is 430 μm, is normalized as 1.

[0030] When the sealing member 16 was provided, a higher light output was obtained in all Examples 1 to 7 than in Comparative Example 3. From the viewpoint of improving the light output, a larger side surface ratio (Sc / Sa) is preferable, and Examples 2 to 7 in which an improvement in light output of 5% or more was observed are preferable. On the other hand, in Examples 6 to 7 in which the side surface ratio (Sc / Sa) exceeds 1, peeling and cracks of the sealing member 16 were observed, and it was found that suitable sealing properties could not be obtained. Therefore, from the viewpoint of sealing properties, Examples 1 to 5 in which the side surface ratio (Sc / Sa) is 1 or less are preferable. From the above, in order to achieve both light output and sealing properties, the side surface ratio (Sc / Sa) is preferably 0.4 to 1.0, and more preferably 0.6 to 1.0. The thickness t of the light-transmitting substrate 20 is preferably 100 μm to 250 μm.

[0031] According to the present embodiment, by providing the sealing member 16, it is possible to cover and protect the semiconductor light emitting element 12 and improve the light output of the semiconductor light emitting device 10. Furthermore, by making the area Sc of the side surface 20c of the light-transmitting substrate 20 equal to or smaller than the area Sa of the top surface 20a, it is possible to prevent peeling or cracking of the sealing member 16 and improve the reliability of the semiconductor light emitting device 10. As a result, it is possible to provide a semiconductor light emitting device 10 with improved light extraction efficiency and reliability.

[0032] 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-mentioned embodiments, that various design changes are possible, that various modifications are possible, and that such modifications are also within the scope of the present invention.

[0033] Several aspects of the present invention will now be described.

[0034] A first aspect of the present invention is a semiconductor light emitting device comprising a package substrate, a semiconductor light emitting element flip-chip bonded onto the package substrate, and a sealing member covering the semiconductor light emitting element on the package substrate and having translucency at the emission wavelength of the semiconductor light emitting element, the semiconductor light emitting element comprising an anode electrode and a cathode electrode bonded to the package substrate, a semiconductor layer on the anode electrode and the cathode electrode, and a translucent substrate on the semiconductor layer, the translucent substrate having an upper surface in contact with the sealing member and a side surface in contact with the sealing member between the upper surface and the semiconductor layer, the area of ​​the side surface being equal to or smaller than the area of ​​the upper surface. According to the first aspect, the light output of the semiconductor light emitting device can be improved by providing a translucent sealing member in contact with the translucent substrate. By making the area of ​​the side surface of the translucent substrate equal to or smaller than the area of ​​the upper surface, peeling or cracking of the sealing member in contact with the translucent substrate can be prevented, and the reliability of the semiconductor light emitting device can be improved.

[0035] A second aspect of the present invention is the semiconductor light emitting device according to the first aspect, wherein an area of ​​the side surface is 0.4 times or more that of the upper surface. According to the second aspect, by increasing the area of ​​the side surface of the light-transmitting substrate, the light output of the semiconductor light emitting device can be further improved.

[0036] A third aspect of the present invention is the semiconductor light emitting device according to the first or second aspect, wherein the thickness of the sealing member covering the upper surface in the normal direction to the upper surface is 0.5 to 2 times the thickness of the light transmissive substrate. According to the third aspect, by making the thickness of the sealing member 0.5 or more times the thickness of the light transmissive substrate, the semiconductor light emitting element can be suitably covered by the sealing member, and the sealing performance can be improved. Furthermore, by making the thickness of the sealing member 2 or less times the thickness of the light transmissive substrate and reducing the amount of the sealing member used, peeling or cracking of the sealing member can be prevented, and the reliability of the semiconductor light emitting device can be improved.

[0037] 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 thickness of the sealing member covering the upper surface in the normal direction to the upper surface is 100 μm or more and 250 μm or less. According to the fourth aspect, by setting the thickness of the sealing member to 100 μm or more and 250 μm or less, the semiconductor light emitting element can be suitably sealed by the sealing member, and peeling or cracking of the sealing member can be prevented.

[0038] 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 thickness of the light transmissive substrate is 100 μm or more and 250 μm or less. According to the fifth aspect, by setting the thickness of the light transmissive substrate to 100 μm or more and 250 μm or less, it is possible to improve both the light output and the reliability of the semiconductor light emitting device.

[0039] A sixth aspect of the present invention is the semiconductor light emitting device according to any one of the first to fifth aspects, wherein the sealing member has a dome shape. According to the sixth aspect, by making the sealing member dome-shaped, the amount of sealing member used to cover the semiconductor light emitting element can be reduced, and peeling or cracking of the sealing member can be prevented. Furthermore, by making the sealing member dome-shaped, the light extraction efficiency of the sealing member can be improved, and the light output of the semiconductor light emitting device can be improved. [Explanation of symbols]

[0040] 10...semiconductor light emitting device, 12...semiconductor light emitting element, 12a...upper surface, 14...package substrate, 16...sealing member, 20...light-transmitting substrate, 20a...upper surface, 20c...side surface, 22...semiconductor layer, 24...anode electrode, 26...cathode electrode, 42...top.

Claims

1. A package substrate; a semiconductor light emitting device that is flip-chip bonded onto the package substrate; a sealing member that covers the semiconductor light emitting element on the package substrate and has a light transmitting property at an emission wavelength of the semiconductor light emitting element, the semiconductor light emitting element includes an anode electrode and a cathode electrode bonded to the package substrate, a semiconductor layer on the anode electrode and the cathode electrode, and a light-transmitting substrate on the semiconductor layer; The light-transmitting substrate has an upper surface in contact with the sealing member, and a side surface between the upper surface and the semiconductor layer in contact with the sealing member, the side surface having an area equal to or smaller than the area of ​​the upper surface.

2. The semiconductor light emitting device according to claim 1 , wherein an area of ​​the side surface is at least 0.4 times an area of ​​the top surface.

3. 2 . The semiconductor light emitting device according to claim 1 , wherein the thickness of the sealing member covering the upper surface in the normal direction to the upper surface is 0.5 to 2 times the thickness of the light-transmitting substrate.

4. 4. The semiconductor light emitting device according to claim 3, wherein the thickness of the sealing member covering the upper surface in the normal direction to the upper surface is not less than 100 [mu]m and not more than 250 [mu]m.

5. 5. The semiconductor light emitting device according to claim 1, wherein the light transmissive substrate has a thickness of 100 μm or more and 250 μm or less.

6. The semiconductor light emitting device according to claim 1 , wherein the sealing member has a dome shape.

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