Light-emitting device and manufacturing method of light-emitting device

Abstract

To provide a light-emitting device that can suppress breaking of the hermetic seal of a light-emitting element, and a manufacturing method thereof.SOLUTION: A light-emitting device includes: a first substrate 21 as a silicon substrate and a second substrate 22 as a silicon substrate bonded to an upper surface of the first substrate and having an opening exposing an area on the upper surface, a first insulating film 24 formed in another area other than one area on the upper surface of the first substrate being a thermally-oxidized film, a second insulating film 25 formed in the one area being an insulating film other than a thermally-oxidized film; a first upper surface electrode 31; a second upper surface electrode 32 formed on a second through-hole group in the one area; a light-emitting element 13 disposed across the first upper surface electrode and the second upper surface electrode on the one area; a first lower surface electrode 28 formed on a first through-hole group on a lower surface of the first substrate; a second lower surface electrode 29 formed on the second through-hole group on the lower surface of the first substrate; and a translucent member 15 with translucency bonded to an upper surface of the second substrate and sealing a space including the opening.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a light emitting device and a method for manufacturing a light emitting device. [Background technology]

[0002] As a light emitting device that irradiates ultraviolet light, a light emitting device that uses a semiconductor light emitting element such as a light emitting diode (LED) as a light source has been disclosed. For example, Patent Document 1 discloses a light emitting device in which a light emitting element made of aluminum gallium nitride (AlGaN) is placed on a mounting substrate and the light emitting element is hermetically sealed on the mounting substrate with a translucent member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-040769 Summary of the Invention [Problem to be solved by the invention]

[0004] In the light-emitting device disclosed in Patent Document 1, for example, the temperature rise and fall process during mounting of the light-emitting element on the mounting substrate may cause cracks in the mounting substrate due to the difference in thermal expansion coefficient between the mounting substrate and the electrodes provided on the mounting substrate.

[0005] For example, if a crack occurs in the mounting substrate, the crack may spread across the surface exposed to the space hermetically sealed by the translucent member and the surface exposed to the external space, causing the gas that hermetically seals the light-emitting element to leak and allowing gas from the external space, i.e., outside air, to enter the hermetically sealed space. This can cause problems such as early deterioration of the light-emitting element due to exposure to humid outside air.

[0006] The present invention has been made in view of the above-mentioned points, and has an object to provide a light emitting device that can prevent the airtight sealing of a light emitting element from being broken, and a method for manufacturing the same. [Means for solving the problem]

[0007] The light emitting device according to the present invention includes a first substrate, which is a silicon substrate including insulating films formed on its upper and lower surfaces, and a second substrate, which is a silicon substrate bonded to the upper surface of the first substrate and has an opening exposing one region of the upper surface of the first substrate, wherein the first insulating film formed in another region other than the one region of the upper surface of the first substrate is a thermal oxide film and the second insulating film formed in the one region is an insulating film other than the thermal oxide film, and the first substrate has a first through hole group including one or more through holes penetrating from a first partial region in the one region to the lower surface of the first substrate and a second insulating film formed in a second partial region in the one region to the lower surface of the first substrate. the first substrate has a substrate structure having a second through-hole group including one or more through-holes that penetrate to the underside of the first substrate; a first upper surface electrode formed on the first through-hole group in one region; a second upper surface electrode formed on the second through-hole group in the first region; a light-emitting element provided on the first region so as to straddle the first upper surface electrode and the second upper surface electrode; a first lower surface electrode formed on the first through-hole group on the underside of the first substrate; a second lower surface electrode formed on the second through-hole group on the underside of the first substrate; and a translucent member bonded to the upper surface of the second substrate and sealing a space including the opening.

[0008] Furthermore, a method for manufacturing a light emitting device according to the present invention includes a first substrate which is a silicon substrate including insulating films formed on its upper and lower surfaces, and a second substrate which is a silicon substrate bonded to the upper surface of the first substrate and has an opening exposing one region on the upper surface of the first substrate, wherein the first insulating film formed in another region other than the one region on the upper surface of the first substrate is a thermal oxide film and the second insulating film formed in the one region is an insulating film other than the thermal oxide film, and the first substrate has a first through hole group including one or more through holes penetrating from a first partial region in the one region to the lower surface of the first substrate and a second through hole group including one or more through holes penetrating from a second partial region in the one region to the lower surface of the first substrate. A method for manufacturing a light-emitting device having a plate structure, a first upper surface electrode formed on a first group of through holes in a first region, a second upper surface electrode formed on a second group of through holes in the first region, a light-emitting element arranged on the first region so as to straddle the first upper surface electrode and the second upper surface electrode, a first lower surface electrode formed on the first group of through holes on the lower surface of the first substrate, a second lower surface electrode formed on the second group of through holes on the lower surface of the first substrate, and a translucent member bonded to the upper surface of the second substrate and sealing a space including an opening, characterized in that the method includes a second insulating film formation step of removing a thermal oxide film formed in one region of the upper surface of the first substrate and forming a second insulating film in the removed one region. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a top view of a light emitting device according to Example 1 of the present invention. [Figure 2] 1 is a cross-sectional view of a light emitting device according to Example 1 of the present invention. [Figure 3] 1 is a cross-sectional view of a step during the manufacturing of the light emitting device according to Example 1 of the present invention. [Figure 4] 1 is a cross-sectional view of a step during the manufacturing of the light emitting device according to Example 1 of the present invention. [Figure 5] 1 is a cross-sectional view of a step during the manufacturing of the light emitting device according to Example 1 of the present invention. [Figure 6]1 is a cross-sectional view of a step during the manufacturing of the light emitting device according to Example 1 of the present invention. [Figure 7] 1 is a cross-sectional view of a step during the manufacturing of the light emitting device according to Example 1 of the present invention. [Figure 8] 1 is a cross-sectional view of a step during the manufacturing of the light emitting device according to Example 1 of the present invention. [Figure 9] 1 is a cross-sectional view of a step during the manufacturing of the light emitting device according to Example 1 of the present invention. [Figure 10] 1 is a cross-sectional view of a step during the manufacturing of the light emitting device according to Example 1 of the present invention. [Figure 11] 1 is a cross-sectional view of a step during the manufacturing of the light emitting device according to Example 1 of the present invention. [Figure 12] 1 is a cross-sectional view of a step during the manufacturing of the light emitting device according to Example 1 of the present invention. [Figure 13] 1 is a cross-sectional view of a step during the manufacturing of the light emitting device according to Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description and accompanying drawings, substantially the same or equivalent parts are designated by the same reference numerals. [Example]

[0011] [Outline of Light-Emitting Device 100] The configuration of a light emitting device 100 according to Example 1 will be described with reference to Figures 1 and 2. Figure 1 is a top view of the light emitting device 100 according to Example 1. Figure 2 is a cross-sectional view of the light emitting device 100 shown in Figure 1 taken along line 2-2.

[0012] The light emitting device 100 is configured to include a substrate structure 11, a light emitting element 13 arranged on the substrate structure 11, and a light-transmitting member 15 that hermetically seals the light emitting element 13 on the substrate structure 11. Note that the light-transmitting member 15 is omitted in Fig. 1 to clearly show the structure and positional relationship of each component. Furthermore, in Fig. 2, the explanation will be given assuming that the up-down direction in the figure is the height direction of the light emitting device 100 and the left-right direction in the figure is the width direction of the light emitting device 100.

[0013] [Substrate structure 11] First, we will explain the configuration of the substrate structure 11. The substrate structure 11 has a first substrate 21 that is a flat plate with a rectangular upper surface shape, and a frame-shaped second substrate 22 that is formed along the outer edge of the upper surface of the first substrate 21 and has an opening 22O that exposes a central area CA (hereinafter also referred to as the central area CA) of the upper surface of the first substrate 21. In other words, the substrate structure 11 is a concave structure that is configured so that the central area CA of the first substrate 21 is exposed by the second substrate 22.

[0014] In the substrate structure 11, the first substrate 21 and the second substrate 22 are both silicon substrates made of single-crystal silicon (Si) whose main surfaces are (100) planes. The substrate structure 11 is a so-called SOI (Silicon On Insulator) substrate in which the first substrate 21 and the second substrate 22 are bonded together via a first insulating film 24, which is a buried oxide film (BOX).

[0015] In the SOI substrate, the first insulating film 24 is a thermal oxide film made of silicon oxide (SiO 2 ) formed on the upper surface of the first substrate 21 by subjecting the first substrate 21 to a thermal oxidation treatment.

[0016] The first substrate 21 has a plurality of through holes 21H that each penetrate the first substrate 21 from a central region CA of the upper surface of the first substrate 21 exposed from the second substrate 22 to the lower surface of the first substrate 21.

[0017] 1, the plurality of through holes 21H are divided into a first through hole group TG1 arranged in a left region within the central region CA of the first substrate 21 and a second through hole group TG2 arranged in a right region within the central region CA and spaced apart from the first through hole group TG1. In other words, the first through hole group TG1 and the second through hole group TG2 are respectively formed in a first partial region within the central region CA and a second partial region arranged so as to form a gap G extending in the up-down direction in FIG. 1 between the first partial region and the second partial region.

[0018] In each of the first through-hole group TG1 and the second through-hole group TG2, the plurality of through-holes 21H are arranged in a regular triangular lattice pattern. In the light emitting device 100, the spacing between the through-holes 21H is the same in the first through-hole group TG1 and the second through-hole group TG2, and the first through-hole group TG has a larger area where the through-holes 21H are formed than the second through-hole group TG2. As a result, the first through-hole group TG1 has a larger number of through-holes 21H than the second through-hole group TG2.

[0019] As described above, the first substrate 21 has the first insulating film 24 formed in a region of the upper surface of the first substrate 21 facing the lower surface of the second substrate 22, i.e., in a region overlapping with the second substrate 22 in a top view. Also, the first substrate 21 has the second insulating film 25 formed from the central region CA to the inner surfaces of each of the through holes 21H and the lower surface of the first substrate 21. That is, on the upper surface of the first substrate 21, the second insulating film 25 is formed in the central region CA, which is one region, and the first insulating film 24 is formed in other regions surrounding the central region CA.

[0020] In the light emitting device 100, the second insulating film 25 is made of a material having a fracture toughness value greater than that of the first insulating film 24 made of SiO2. Specifically, the second insulating film 25 has a fracture toughness value of, for example, 0.3 MPa·m 1 / 2 5-6 MPa m, more than 10 times that of SiO2 1 / 2 It is made of silicon nitride (SiN) with a fracture toughness value of

[0021] In the light emitting device 100, the second insulating film 25 is formed to a thickness of 0.3 μm by, for example, a plasma CVD (Chemical Vapor Deposition) method. Furthermore, the film stress of the second insulating film 25, which is the internal stress of the film 25, is controlled to be ±50 MPa or less during the formation process by the plasma CVD method.

[0022] The first substrate 21 has columnar through electrodes 26 made of Cu that are filled inside each of the through holes 21H via a second insulating film 25 so as to penetrate the first substrate 21. That is, the through electrodes 26 are insulated from each other by the second insulating film 25 formed on the inner surface of each of the through holes 21H, and are exposed from a central region CA of the upper surface of the first substrate 21 and the lower surface of the first substrate 21.

[0023] The first substrate 21 has a first lower surface electrode 28 and a second lower surface electrode 29, each having a rectangular upper surface shape, formed and spaced apart from each other on the lower surface of the first substrate 21. When viewed from a direction perpendicular to the lower surface of the first substrate 21, the first lower surface electrode 28 is electrically connected to each of the through electrodes 26 arranged in the through holes 21H belonging to the first through hole group TG1 so as to cover each of the through holes 21H.

[0024] Further, the second lower surface electrode 29 is electrically connected to each of the through electrodes 26 arranged in the through holes 21H so as to cover each of the through holes 21H belonging to the second through hole group TG2 when viewed from a direction perpendicular to the lower surface of the first substrate 21. That is, the first lower surface electrode 28 and the second lower surface electrode 29 are arranged with a gap G extending in the up-down direction in FIG.

[0025] The first lower electrode 28 and the second lower electrode 29 are formed by laminating titanium (Ti), copper (Cu), nickel (Ni), and gold (Au) in this order from the lower surface side of the first substrate 21. The first lower electrode 28 and the second lower electrode 29 function as mounting electrodes when the light emitting device 100 is mounted on a mounting substrate (not shown).

[0026] The first substrate 21 has a first upper surface electrode 31 and a second upper surface electrode 32, each having a rectangular upper surface shape, formed to be spaced apart from each other in a central region CA of the upper surface of the first substrate 21. When viewed from a direction perpendicular to the upper surface of the first substrate 21, the first upper surface electrode 31 is electrically connected to each of the through electrodes 26 arranged in the through holes 21H belonging to the first through hole group TG1 so as to cover each of the through holes 21H.

[0027] Moreover, the second upper surface electrode 32 is electrically connected to each of the through electrodes 26 arranged in the through holes 21H so as to cover each of the through holes 21H belonging to the second through hole group TG2 when viewed from a direction perpendicular to the upper surface of the first substrate 21. That is, the first upper surface electrode 31 and the second upper surface electrode 32 are arranged with a gap G extending in the up-down direction in FIG.

[0028] Therefore, the first upper surface electrode 31 is electrically connected to the first lower surface electrode 28 via each of the through electrodes 26 in the first through hole group TG1. The second upper surface electrode 32 is electrically connected to the second lower surface electrode 29 via each of the through electrodes 26 in the second through hole group TG2. The first upper surface electrode 31 and the second upper surface electrode 32 are formed by laminating Ti / Cu / Ni in this order from the upper surface side of the first substrate 21.

[0029] The Cu film included in each of the first lower electrode 28, the second lower electrode 29, the first upper electrode 31, and the second upper electrode 32 has a sufficient thickness to dissipate heat generated when the light-emitting element 13 described below is driven. For example, the Cu film included in each electrode has a thickness of about 20 to 30 μm.

[0030] As described above, the second substrate 22 has an opening 22O that exposes the central region CA of the upper surface of the first substrate 21. The inner surface of the second substrate 22 that forms the opening 22O is inclined so as to widen from the lower surface toward the upper surface of the second substrate 22. In other words, the recess of the substrate structure 11 has the shape of an inverted truncated quadrangular pyramid.

[0031] In the light emitting device 100, the inner surface of the second substrate 22 is inclined at an angle of approximately 54.7° with respect to the upper surface of the first substrate 21. The (111) plane of the silicon crystal is exposed on the inner surface inclined at this angle.

[0032] The second substrate 22 has a thermal oxide film 34 formed on the top surface and inner surface thereof. Like the first insulating film 24, the thermal oxide film 34 is an insulating film made of SiO2 and formed by subjecting the second substrate 22 to a thermal oxidation treatment.

[0033] [Light-emitting element 13] Next, the configuration of the light-emitting element 13 will be described. The light-emitting element 13 is a light-emitting diode with a rectangular top surface provided in a central region CA of the top surface of the first substrate 21. In other words, the light-emitting element 13 is provided on the bottom surface of a recess in the substrate structure 11. The light-emitting element 12 is configured to include a semiconductor structure layer 41, a transparent substrate 42, an n-electrode 43, and a p-electrode 44.

[0034] The semiconductor structure layer 41 is a semiconductor laminate including an n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer (none of which are shown), each of which is made primarily of AlGaN. When the light emitting device 100 is driven, the light emitting layer of the semiconductor structure layer 41 emits light having a wavelength in the deep ultraviolet region, for example, a wavelength of 100 to 280 nm.

[0035] The transparent substrate 42 is a flat substrate provided on the semiconductor structure layer 41. The transparent substrate 42 is made of a material such as aluminum nitride (AlN) that is transparent to ultraviolet light emitted from the light emitting layer of the semiconductor structure layer 41. The transparent substrate 42 also serves as a growth substrate for growing semiconductor crystals that will become the semiconductor structure layer 41 described above.

[0036] The n-electrode 43 and the p-electrode 44 are electrodes formed by plating Cu with Au, which is connected to the n-type semiconductor layer and the p-type semiconductor layer, respectively, of the semiconductor structure layer 41. The n-electrode 43 and the p-electrode 44 are bonded to the first upper surface electrode 31 and the second upper surface electrode 32, respectively, via a bonding layer 46 made of gold-tin (AuSn). That is, in the light-emitting device 100, the light-emitting element 13 is flip-chip mounted on the first substrate 21 of the substrate structure 11.

[0037] The bonding layer 46 is heated, melted, and solidified to bond the light emitting element 13 to the first upper electrode 31 and the second upper electrode 32. The Ni layer constituting the first upper electrode 31 and the second upper electrode 32 functions as a barrier layer that prevents the Cu layer below the Ni layer and the AuSn constituting the bonding layer 46 from diffusing and mixing when the bonding layer 46 is heated and melted.

[0038] [Translucent member 15] Next, the configuration of the light-transmitting member 15 will be described. The light-transmitting member 15 is a plate-like body with a rectangular upper surface that is bonded to the upper surface of the second substrate 22 via a glass bonding layer 48 made of a paste containing powdered glass frit. The light-transmitting member 15 is made of glass that is made mainly of SiO2 and that transmits deep ultraviolet light emitted from the light-emitting element 13.

[0039] In the light emitting device 100, ultraviolet light emitted from the light emitting element 13 enters the lower surface of the light-transmitting member 15 and exits from the upper surface of the light-transmitting member 15. In other words, the upper surface of the light-transmitting member 15 functions as a light extraction surface of the light emitting device 100.

[0040] The light-transmitting member 15 is bonded to the upper surface of the second substrate 22 via a glass bonding layer 48, thereby hermetically sealing the light-emitting element 13 disposed in the opening 22O. Specifically, the light-transmitting member 15 and the substrate structure 11 define a space SP (see FIG. 2) that is an accommodation space, and by sealing the space SP with a gas that is not altered by ultraviolet light, such as nitrogen (N2) gas, the light-emitting element 13 is prevented from being exposed to the outside air.

[0041] Note that, in bonding between the light-transmitting member 15 and the second substrate 22, a bonding layer made of, for example, AuSn may be used instead of using the glass bonding layer 48. In this case, metallized layers in which Ni and Au are laminated in this order are formed on the lower surface of the light-transmitting member 15 and the upper surface of the second substrate 22, respectively, and a layer made of AuSn is disposed between the metallized layers, thereby bonding the light-transmitting member 15 and the second substrate 22.

[0042] [Suppression of sealing gas leakage] Here, the suppression of leakage of the sealing gas sealing the light emitting element 13, which is achieved by the light emitting device 100 of this embodiment, will be described with reference to FIGS.

[0043] In the light emitting device 100, the second insulating film 25 formed over the central region CA of the upper surface of the first substrate 21, the inner surfaces of each of the through holes 21H, and the lower surface of the first substrate 21 is made of SiN, which has a fracture toughness value greater than that of SiO2, the first insulating film 24, as described above. This makes it possible to prevent brittle fracture from occurring in the second insulating film 25 itself in the light emitting device 100, and to prevent cracks from progressing from the second insulating film 25 to the first substrate 21.

[0044] When mounting the light-emitting element 13 on the first substrate 21, the light-emitting element 13 is placed on a bonding layer 46 made of AuSn, and the temperature is raised from room temperature to approximately 260°C to 320°C to melt and solidify the bonding layer 46, thereby bonding the light-emitting element 13 to the first upper electrode 31 and the second upper electrode 32.

[0045] Here, Cu contained in each of the first lower surface electrode 28, the second lower surface electrode 29, the first upper surface electrode 31, and the second upper surface electrode 32 has a relatively large thermal expansion coefficient and expands significantly with increasing temperature, particularly in a temperature range near the melting point of the above-mentioned bonding layer 46. On the other hand, Si constituting the first substrate 21 has a smaller thermal expansion coefficient than Cu, and therefore expands less than Cu at the same temperature.

[0046] When the light-emitting element 13 is mounted, such a situation occurs, causing the first lower electrode 28, the second lower electrode 29, the first upper electrode 31, and the second upper electrode 32 to expand and contract, resulting in thermal stress on the first substrate 21.

[0047] Specifically, for example, on the underside of the first substrate 21, when the thermally expanded first lower electrode 28 and second lower electrode 29 contract as the temperature drops, tensile stresses are generated that pull them in opposite directions relative to the first substrate 21, and on the upper side of the first substrate 21, when the thermally expanded first upper electrode 31 and second upper electrode 32 contract as the temperature drops, tensile stresses are generated that pull them in opposite directions relative to the first substrate 21.

[0048] When such tensile stress occurs in the first substrate 21, a large force is likely to be applied to, for example, the area AR shown surrounded by the two-dot chain line in Figure 2, i.e., the area between the first bottom electrode 28 and the second bottom electrode 29 and the area between the first top electrode 31 and the second top electrode 32.

[0049] For example, when the first insulating film 24 made of SiO2 is formed on both the upper and lower surfaces of the first substrate 21, the fracture toughness of SiO2 is 0.3 MPa·m 1 / 2 Since the tensile stress is relatively small, brittle fracture occurs in the region AR when the region AR is subjected to the above-mentioned tensile stress, and a crack occurs in the first insulating film 24. The generated crack propagates, for example, along the vertical direction in FIG. 1 through the gap G between the first through-hole group TG1 and the second through-hole group TG2.

[0050] Cracks tend to propagate from the first insulating film 24, which is a thermal oxide film formed by thermally oxidizing Si, to the first substrate 21 made of Si. Therefore, if a crack occurs in the first insulating film 24 in the above-described region AR, the crack may propagate through the first substrate 21 and eventually connect with each other.

[0051] Furthermore, even if a crack occurs in only one of the regions AR in FIG. 2, the crack may eventually penetrate through the first substrate 21 as it propagates from one side to the other.

[0052] For example, if a crack penetrates the first substrate 21, there is a risk that the gas that hermetically seals the light emitting element 13 may leak to the outside. If this occurs, for example, external air containing moisture may enter the space SP of the substrate structure 11, which may cause early deterioration of the light emitting element 13.

[0053] In the light emitting device 100 of this embodiment, as described above, the second insulating film 25 made of SiN having a fracture toughness value greater than SiO2, specifically, a fracture toughness value 10 times or more greater than SiO2, is formed over the central region CA of the upper surface of the first substrate 21, the inner side surfaces of each of the through holes 21H, and the lower surface of the first substrate 21. In other words, the second insulating film 25 is not susceptible to brittle fracture when stress is generated in the second insulating film 25.

[0054] Therefore, according to the light-emitting device 100 of this embodiment, even when thermal stress is applied to the first substrate 21 due to thermal expansion of Cu contained in each of the first lower electrode 28, the second lower electrode 29, the first upper electrode 31 and the second upper electrode 32 when the light-emitting element 13 is mounted on the first substrate 21, the use of the second insulating film 25 having a relatively large fracture toughness value can prevent cracks from progressing in the first substrate 21.

[0055] Therefore, according to the light emitting device 100 of this embodiment, it is possible to prevent the airtight seal of the light emitting element 13 from being broken, causing the sealing gas to leak and the light emitting element 13 to be exposed to humid outside air.

[0056] In the light emitting device 100 of this embodiment, the second insulating film 25 is formed over the central region CA on the upper surface of the first substrate 21 and the inner and lower surfaces of the through holes 21H, but this is not limiting and it is sufficient that the second insulating film 25 is formed at least in the central region CA on the upper surface of the first substrate 21. Therefore, an insulating film other than the second insulating film 25, for example, the first insulating film 24, may be formed on the inner and lower surfaces of each of the through holes 21H of the first substrate 21.

[0057] Even in such a case, even if a crack occurs from the underside of the first substrate 21, i.e., in the first insulating film 24, and progresses toward the upper surface, the second insulating film 25 suppresses the progress of the crack, thereby preventing the airtight seal of the light-emitting element 13 from being broken.

[0058] Furthermore, in the light emitting device 100 of this embodiment, the second insulating film 25 is made of SiN, which has a fracture toughness value greater than that of SiO2 (first insulating film 24), but this is not limited to this and other materials may also be used.

[0059] For example, instead of SiN, zirconium oxide (ZrO2), aluminum oxide (Al2O3), or silicon carbide (SiC) may be used for the second insulating film 25. The fracture toughness value of ZrO2 is approximately 7 to 8 MPa m 1 / 2 The fracture toughness values ​​of Al2O3 and SiC are approximately 3 to 4 MPa m 1 / 2 is.

[0060] In the light-emitting device 100 of this embodiment, the second insulating film 25 made of SiN, which has a fracture toughness value greater than that of the first insulating film 24 made of SiO2, is formed on the central region CA of the upper surface of the first substrate 21, the inner surface and the lower surface of the through hole 21H, but it is also possible to simply form a new film regardless of the fracture toughness value.

[0061] For example, instead of the first insulating film 24 being a thermal oxide film, an insulating film made of SiO2 formed by plasma CVD or the like may be formed. That is, even if it is the same SiO2, the original thermal oxide film may be peeled off and a new film may be formed by a method other than thermal oxidation processing.

[0062] The newly formed insulating film has a lower degree of bonding (adhesion) with the first substrate 21 than a thermally oxidized film. Therefore, even if a crack occurs in the insulating film, the crack is less likely to propagate to the first substrate 21. Therefore, a better effect of suppressing crack propagation can be expected compared to when the first insulating film 24 is formed on the first substrate 21 as a thermally oxidized film.

[0063] In the light emitting device 100 of this embodiment, a plurality of through holes 21H are formed in each of the first through hole group TG1 and the second through hole group TG2 in the first substrate 21, but this is not limited thereto, and the number of through holes 21H may be one in each through hole group. In this case, the diameter of one through hole 21H may be set to be large.

[0064] [verification] Here, we will explain the verification performed on the light emitting device 100 of this example and the verification results. In this verification, a 2.6 mm square silicon substrate simulating the first substrate 21 was prepared, an insulating film having a thickness of 0.3 μm was formed on the top and bottom surfaces of the prepared silicon substrate, and two Cu electrodes each having a thickness of 25 μm were formed spaced apart from each other only on the bottom surface of the silicon substrate, and this was used as a sample.

[0065] In this study, the first sample was a silicon substrate with a SiN insulating film, and the second sample was a comparative example with a SiO2 insulating film. That is, the first and second samples differed only in the material composition of the insulating film.

[0066] In this verification, 27 samples each of the first and second samples described above were prepared, and each sample was placed on a hot plate heated to 260°C for 2 minutes, then placed on a heat sink to rapidly cool, after which the presence or absence of cracks in the insulating film and silicon substrate was confirmed using an optical microscope.

[0067] The number of samples in which cracks occurred in the first and second samples in this verification is shown in Table 1. From the results shown in Table 1, no cracks were found in any of the 27 first sample samples. On the other hand, cracks were found in 15 of the 27 second sample samples, which are comparative examples.

[0068] [Table 1]

[0069] The above results show that by using a SiN film, which has a higher fracture toughness than SiO2, instead of a SiO2 film as the insulating film formed on the silicon substrate, cracks are less likely to occur in the sample. Therefore, by forming a second insulating film 25 made of SiN on the first substrate 21 as in the light-emitting device 100, it is possible to prevent cracks from occurring in the first substrate 21 when, for example, the light-emitting element 13 is mounted.

[0070] Although not shown, in the above verification, the thickness of the SiN film formed on the silicon substrate was changed to check for the presence or absence of cracks. As a result, it was found that no cracks occurred in the sample when the thickness of the SiN film was set to approximately 0.3 to 2.0 μm.

[0071] [Method of manufacturing a light-emitting device] Next, a method for manufacturing the light emitting device 100 according to Example 1 of the present application will be described with reference to Figures 3 to 13. Each of Figures 3 to 13 is a cross-sectional view of one step during the manufacturing of the light emitting device 100. In each of Figures 3 to 13, the cross section taken along line 2-2 shown in Figure 1 will be used for the description, as in Figure 2.

[0072] In this embodiment, the light emitting device 100 is manufactured in a wafer level package (WLP) manner in which a plurality of light emitting devices 100 are manufactured collectively on a wafer-shaped substrate structure 11, and then the light emitting devices 100 are diced into individual pieces. Each of Figures 3 to 13 shows division lines CL, which are division lines along which the light emitting devices 100 are diced into individual pieces.

[0073] 3, a substrate structure 11 is prepared in which a first substrate 21 made of single crystal Si and a second substrate 22 made of single crystal Si are bonded together, the first substrate 21 having a first insulating film 24 made of SiO2 formed on its upper surface as a buried oxide film (Step S1: Substrate structure preparation step). Note that a SiO2 film, which is a natural oxide film, is formed on the lower surface of the first substrate 21 and the upper surface of the second substrate 22, but the natural oxide film is not shown in the present description.

[0074] 4, etching is performed from the underside of the first substrate 21 to form a plurality of columnar holes 21HA that will become a plurality of through holes 21H in a step described later (step S2: hole forming step). Each of the plurality of holes 21HA is formed using, for example, deep reactive ion etching (DRIE) using the Bosch process. In forming the plurality of holes 21HA, the first insulating film 24 functions as an etching stop layer.

[0075] Although not shown, this process includes a step of applying photoresist to the lower surface of first substrate 21 and a step of removing the photoresist after etching to form multiple holes 21HA.

[0076] 5, a thermal oxide film 34A made of SiO2 is formed from the lower surface of first substrate 21 to the inner surfaces of holes 21HA and over the upper surface of first substrate 21 by wet thermal oxidation, which involves heating in a water vapor atmosphere at 1100°C for 7 hours or more (step S3: thermal oxide film formation step). The thermal oxide film 34A formed in this step serves as an etching stop layer on the inner surfaces of holes 21HA when etching is performed in the next step.

[0077] 6, wet etching is performed using a tetramethylammonium hydroxide aqueous solution (TMAH) until the first insulating film 24 formed on the upper surface of the first substrate 21 is exposed from the upper surface of the second substrate 22, thereby forming an opening 22O (step S4: opening formation step). That is, a recess is formed in the substrate structure 11. In forming the opening 22O, the first insulating film 24 functions as an etching stop layer.

[0078] In this process, so-called crystal anisotropic etching is performed, which utilizes the difference in etching rate depending on the crystal plane of Si. As a result, as the etching progresses, the (111) plane appears on the inner surface of the second substrate 22, which is more difficult to etch than the (100) plane, i.e., has a slower etching rate.

[0079] 7, the thermal oxide film 34A and the first insulating film 24 exposed in the central region CA of the upper surface of the first substrate 21 are removed using buffered hydrofluoric acid (BHF) (step S5: oxide film removal step). By removing the first insulating film 24 exposed in the central region CA of the upper surface of the first substrate 21, each of the holes 21HA formed in step S2 communicates with the central region CA, forming a plurality of through-holes 21H. Furthermore, this step leaves the first insulating film 24 only in the peripheral region surrounding the central region CA of the upper surface of the first substrate 21.

[0080] 8, a thermal oxide film 34 is formed on the upper surface and inner surface of the second substrate 22 (step S6: thermal oxide film formation step). The thermal oxide film 34 is formed by, for example, wet thermal oxidation in which the first substrate 21 is heated in a water vapor atmosphere at 1100°C for 7 hours or more while the central region CA of the upper surface and the lower surface of the first substrate 21 are masked.

[0081] 9, a second insulating film 25 is formed over the central region CA on the upper surface of the first substrate 21, the inner surfaces of the through holes 21H, and the lower surface of the first substrate 21 (step S7: second insulating film formation process). The second insulating film 25 is formed to a predetermined film thickness by plasma CVD, for example, while masking the upper surface and inner surfaces of the second substrate 22.

[0082] The second insulating film 25 may be formed by a film formation method such as LP (Low Pressure)-CVD or Atomic Layer Deposition (ALD) instead of the plasma CVD method.

[0083] 10, a plurality of through electrodes 26 made of Cu are formed inside each of the plurality of through holes 21H (step S8: through electrode forming process). The through electrodes 26 are formed, for example, by forming a seed layer (not shown) in which Ti and Cu are laminated in this order on the lower surface of the first substrate 21 and on a part of the inner surface of the through hole 21H, and then masking the lower surface of the first substrate 21 and filling Cu onto the seed layer from the lower surface to the upper surface of the first substrate 21 by electrolytic plating.

[0084] Next, as shown in FIG. 11, a first upper surface electrode 31 and a second upper surface electrode 32 are formed in the central region CA of the upper surface of the first substrate 21, a first lower surface electrode 28 and a second lower surface electrode 29 are formed on the lower surface of the first substrate 21, and an AuSn layer 46A that serves as the base material of the bonding layer 46 is formed on the first lower surface electrode 28 and the second lower surface electrode 29 (step S9: electrode formation process).

[0085] In step S9, a seed layer (not shown) of Ti / Cu is formed by sputtering over a central region CA of the upper surface of first substrate 21, and after masking the portions excluding the respective upper surface electrodes with resist, a Cu / Ni layer and an AuSn layer 46A are respectively deposited by electrolytic plating. Thereafter, the resist used for the mask is removed, and the remaining seed layer is etched, thereby forming first upper surface electrode 31, second upper surface electrode 32, and AuSn layer 46A.

[0086] In addition, in step S9, the first lower surface electrode 28 and the second lower surface electrode 29 are formed by masking the portions of the lower surface of the first substrate 21 other than the respective lower surface electrodes with resist, and then laminating Ni / Au in this order by electrolytic plating.

[0087] 12, the light emitting element 13 is mounted in the central region CA of the upper surface of the first substrate 21 (step S10: element mounting process). The light emitting element 13 is mounted by, for example, heating the substrate structure 11 on which the light emitting element 13 is mounted at 340°C for 30 seconds in a nitrogen (N2) atmosphere, and eutectic bonding the Au layers formed on the surfaces of the n-electrode 43 and the p-electrode 44 with the AuSn layer 46A.

[0088] 13, the light-transmitting member 15 is bonded to the upper surface of the second substrate 22 (step S11: light-transmitting member bonding step). In this step, a glass bonding layer 48 is formed in advance on the light-transmitting member 15, and the light-transmitting member 15 on which the glass bonding layer 48 has been formed is disposed so as to cover the opening 22O.

[0089] In this process, the glass bonding layer 48 is applied to the lower surface of the translucent member 15 at a position corresponding to the upper surface of the second substrate 22, so as to surround the opening 22O and to a size that does not overlap with the dividing line CL of the substrate structure 11.

[0090] Thereafter, in an N2 atmosphere, laser light having a near-infrared wavelength is irradiated onto glass bonding layer 48 from above light-transmitting member 15 placed on the upper surface of second substrate 22, locally heating and melting glass bonding layer 48, thereby bonding light-transmitting member 15 to the upper surface of second substrate 22. At this time, the melted glass bonding layer 48 and the thermal oxide film 34 formed on the upper surface of second substrate 22 interdiffuse to form an interdiffusion layer (not shown). As a result, opening 22O is filled with N2, an inert gas, and a space SP is formed that is airtightly sealed.

[0091] The laser light irradiated onto the glass bonding layer 48 is scanned along the shape of the upper surface of the second substrate 22. The scanning time of the laser light is approximately 2 to 3 seconds per light emitting device 100. Therefore, in each light emitting device 100, the glass bonding layer 48 is heated locally and in a short time by the laser light. This prevents the bonding layer made of AuSn that bonds the light emitting element 13 from remelting due to overheating.

[0092] In conventional light emitting devices, hermetic sealing is achieved twice using AuSn eutectic bonding: once for bonding the light emitting element and once for bonding the light-transmitting member to the AlN substrate. During this process, the bonding layer 46 bonding the light emitting element may re-melt during the second AuSn eutectic bonding for bonding the light-transmitting member, potentially resulting in manufacturing defects such as misalignment of the light emitting element.

[0093] In the manufacturing method of the light emitting device 100 of this embodiment, as described above, the glass bonding layer 48 is locally and quickly heated using laser light to achieve airtight sealing. This prevents the bonding layer 46 that bonds the light emitting element 13 from remelting, and suppresses manufacturing defects such as misalignment of the light emitting element.

[0094] Finally, the substrate structure 11 to which the light-transmitting member 15 is bonded is set in a dicer device, and the light-transmitting member 15 and the substrate structure 11 are cut along the division lines CL to separate the light-emitting devices 100 (step S12: singulation step). Through the above steps, the light-emitting device 100 as shown in FIG. 2 can be obtained.

[0095] As described above, the light emitting device 100 of this embodiment can be manufactured as a wafer-level package in which the light emitting devices 100 are formed in a lattice pattern on a silicon wafer. Conventionally, individual AlN substrates have been used and the substrates have had to be hermetically sealed one by one, which has caused problems in terms of takt time and cost during manufacturing.

[0096] In the manufacturing method of the light-emitting device 100 of this embodiment, the substrate structure 11 to which the light-transmitting member 15 is bonded is set in a dicer device and cut, so that multiple light-emitting devices 100 can be manufactured at once, thereby making it possible to shorten the takt time during manufacturing and reduce costs. [Explanation of symbols]

[0097] 100 Light-emitting device 11 Substrate structure 13 Light-emitting element 15 Translucent material 21 First substrate 22 Second board 24 First insulating film 25 Second insulating film 26 Through electrode 28 First lower electrode 29 Second lower electrode 31 First upper electrode 32 second upper electrode 34 Thermal oxide film 41 Semiconductor structure layer 42 Transparent substrate 43 n electrode 44p electrode 46 Bonding layer 48 Glass bonding layer

Claims

1. a substrate structure including a first substrate which is a silicon substrate including insulating films formed on its upper and lower surfaces, and a second substrate which is a silicon substrate bonded to the upper surface of the first substrate and has an opening exposing one region of the upper surface of the first substrate, wherein the first insulating film formed in another region of the upper surface of the first substrate other than the first region is a thermal oxide film and the second insulating film formed in the one region is an insulating film other than the thermal oxide film, and the first substrate has a first through-hole group including one or more through-holes penetrating from a first partial region in the one region to the lower surface of the first substrate and a second through-hole group including one or more through-holes penetrating from a second partial region in the one region to the lower surface of the first substrate; a first upper surface electrode formed on the first group of through holes in the first region; a second upper surface electrode formed on the second group of through holes in the first region; a light-emitting element provided on the one region so as to straddle the first upper surface electrode and the second upper surface electrode; a first lower surface electrode formed on the lower surface of the first substrate and above the first group of through holes; a second lower surface electrode formed on the lower surface of the first substrate over the second group of through holes; a light-transmitting member bonded to an upper surface of the second substrate and sealing a space including the opening; A light emitting device comprising:

2. 2. The light emitting device according to claim 1, wherein the second insulating film has a fracture toughness value greater than that of the first insulating film.

3. 3. The light emitting device according to claim 2, wherein the second insulating film is made of any one of silicon nitride, zirconium oxide, aluminum oxide, and silicon carbide.

4. The light-emitting device described in claim 1, characterized in that the second insulating film is formed on the inner surface of each of one or more through holes in the first through hole group and the second through hole group, and a through electrode that penetrates the first substrate is formed inside each of the one or more through holes in which the second insulating film is formed.

5. 5. The light emitting device according to claim 2, wherein the insulating film formed on the lower surface of the first substrate is the second insulating film.

6. the second substrate has the thermal oxide film formed on an upper surface thereof; 3. The light-emitting device according to claim 1, wherein the translucent member is bonded to the upper surface of the second substrate via a glass bonding layer made of the thermal oxide film and glass frit disposed on the thermal oxide film.

7. 3. The light emitting device according to claim 1, wherein the inner surface of the second substrate forming the opening is a (111) plane of silicon crystal.

8. 3. The light emitting device according to claim 1, wherein each of the one or more through holes belonging to the first through hole group and the second through hole group is formed in a triangular lattice pattern.

9. The present invention includes a first substrate, which is a silicon substrate including insulating films formed on its upper and lower surfaces, and a second substrate, which is a silicon substrate bonded to the upper surface of the first substrate and has an opening exposing one region of the upper surface of the first substrate, wherein the first insulating film formed in another region of the upper surface of the first substrate other than the first region is a thermal oxide film and the second insulating film formed in the first region is an insulating film other than the thermal oxide film, and the first substrate has a first through-hole group including one or more through-holes penetrating from a first partial region in the first region to the lower surface of the first substrate and a second through-hole group penetrating from a second partial region in the first region to the lower surface of the first substrate. a substrate structure having a second through-hole group including one or more through holes formed through the opening, a first upper surface electrode formed on the first through-hole group in the first region, a second upper surface electrode formed on the second through-hole group in the first region, a light-emitting element provided on the first region so as to straddle the first upper surface electrode and the second upper surface electrode, a first lower surface electrode formed on the first through-hole group on a lower surface of the first substrate, a second lower surface electrode formed on the second through-hole group on the lower surface of the first substrate, and a light-transmitting member bonded to the upper surface of the second substrate and sealing a space including the opening, A method for manufacturing a light-emitting device, comprising a second insulating film formation step of removing the thermal oxide film formed in the one region on the upper surface of the first substrate, and forming the second insulating film in the one region from which the thermal oxide film has been removed.

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