LED Package

Abstract

This provides an LED package that can extract infrared light emitted from an LED chip to the outside with higher efficiency than conventional methods. [Solution] An LED package including an LED chip that emits infrared light with a peak wavelength of 1,000 nm to 2,000 nm, comprising: a substrate 7 made of an insulating material on which the LED chip is flip-chip mounted; a pair of first conductive regions formed spaced apart from each other on a first surface 7a of the substrate; a pair of through electrodes 33 formed that penetrate the substrate at spaced-apart positions and individually contact the pair of first conductive regions 31; a pair of second conductive regions 32 formed spaced apart from each other on a second surface 7b of the substrate opposite to the first surface and individually contacting the pair of through electrodes; and a first light-reflecting region 31 made of a material with higher reflectivity to infrared light than the substrate, formed at least outside the LED chip on the first surface of the substrate when viewed from the side of the first surface of the substrate in the direction normal to the first surface.

Description

[Technical Field]

[0001] The present invention relates to an LED package on which an LED chip is mounted, and more particularly to an LED package that emits infrared light. [Background technology]

[0002] In recent years, semiconductor light-emitting devices with emission wavelengths in the infrared region of 1000 nm or higher have been widely used in applications such as security and surveillance cameras, gas detectors, medical sensors, and industrial equipment.

[0003] Semiconductor light-emitting devices with emission wavelengths of 1000 nm or more are generally manufactured using the following procedure: A first conductivity type semiconductor layer, an active layer (sometimes called the "emission-emitting layer"), and a second conductivity type semiconductor layer are sequentially epitaxially grown on an InP substrate as a growth substrate. Then, electrodes for current injection are formed on the semiconductor wafer. After that, the wafer is cut into chip shapes.

[0004] Traditionally, the development of semiconductor laser devices has taken precedence among semiconductor light-emitting elements with emission wavelengths of 1000 nm or more. On the other hand, LED devices have not progressed as much as laser devices, partly because their applications have been limited.

[0005] However, in recent years, with the expansion of applications, there has been a growing demand for high-efficiency infrared LED elements. The applicant has previously proposed technology for infrared LED elements with emission wavelengths of 1000 nm or more that exhibit high light extraction efficiency (see Patent Document 1). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-65415 [Overview of the project] [Problems that the invention aims to solve]

[0007] LED elements are sometimes packaged and used while mounted on a substrate. Patent Document 1 mentions the structure of an infrared LED element, i.e., the structure as an LED chip, but does not provide detailed information about the package.

[0008] Various research and development efforts have been made to improve the light extraction efficiency of visible light LEDs. Visible light LEDs generate blue light using nitride-based (GaN-based) semiconductors, and then convert a portion of the blue light's wavelength through a phosphor to produce visible light. GaAs-based semiconductors are also often used for red light LEDs.

[0009] In contrast, to obtain infrared light with a peak wavelength exceeding 1,000 nm, InP-based semiconductors are used. Compared to GaN-based and GaAs-based semiconductors, InP-based semiconductors have the drawback of exhibiting a significant decrease in light output with increasing temperature. For example, comparing GaN-based and InP-based semiconductors, the ratio of light output at 85°C to light output at 25°C is maintained at approximately 90% for GaN-based LEDs with a peak wavelength of 450 nm, while it drops to approximately 20% for InP-based LEDs with a peak wavelength of 1,650 nm. Therefore, for LEDs emitting infrared light with a peak wavelength exceeding 1,000 nm, it is even more important to improve the light extraction efficiency compared to visible light LEDs.

[0010] In view of the above problems, the present invention aims to provide an LED package that can extract infrared light emitted from an LED chip to the outside with higher efficiency than conventional methods. [Means for solving the problem]

[0011] The LED package according to the present invention is An LED package including an LED chip that emits infrared light with a peak wavelength of 1,000 nm to 2,000 nm, A substrate made of an insulating material on which the LED chip is flip-chip mounted, A pair of first conductive regions formed on the first surface on the LED chip side of the substrate, spaced apart from each other, and respectively contacting the anode electrode and the cathode electrode of the LED chip via conductive bonding members, the pair of first conductive regions being composed of a first conductive region on the anode electrode side and a first conductive region on the cathode electrode side; A pair of through electrodes formed by penetrating the substrate at positions spaced apart from each other and respectively contacting the pair of first conductive regions, the pair of through electrodes being composed of a through electrode on the anode electrode side and a through electrode on the cathode electrode side; A pair of second conductive regions formed on the second surface of the substrate opposite to the first surface, spaced apart from each other, and respectively contacting the pair of through electrodes, the pair of second conductive regions being composed of a second conductive region on the anode electrode side and a second conductive region on the cathode electrode side; Characterized by comprising a first light reflection region formed at a position on the first surface of the substrate at least outside the LED chip as viewed in the normal direction of the first surface from the side of the first surface of the substrate, and made of a material having higher reflectivity to infrared light than the substrate. 。

[0012] The expression "pair of first conductive regions" is used in the sense that the "first conductive regions" are composed of the "first conductive region on the anode electrode side" electrically connected to the anode electrode of the LED chip and the "first conductive region on the cathode electrode side" electrically connected to the cathode electrode of the LED chip. In other words, the notation "pair of" here indicates that it is a pair in the sense of "anode electrode side" and "cathode electrode side", and it is not intended to limit the number to two. For example, when the "first conductive region on the anode electrode side" electrically connected to the anode electrode of the LED chip is formed at two locations on the first surface of the substrate, and the "first conductive region on the cathode electrode side" electrically connected to the cathode electrode of the LED chip is formed at a location separated from the "first conductive region on the anode electrode side" on the first surface of the substrate, although the number of first conductive regions is three, since they are a pair in the sense of "anode electrode side" and "cathode electrode side", they are "a pair of first conductive regions".

[0013] The notations "pair of through electrodes" and "pair of second conductive regions" have the same meaning, and both indicate that they are a pair in the sense of "anode electrode side" and "cathode electrode side".

[0014] Flip chip mounting is a mode in which an LED chip with a semiconductor formed on the upper layer of a substrate is mounted on the substrate through a conductive bonding member in a state where the substrate is inverted so that the substrate is on the opposite side to the base body.

[0015] In an LED package in which an LED chip is flip chip mounted, light is extracted toward the side opposite to the base body (substrate side). Hereinafter, this region is referred to as the "light extraction surface".

[0016] Most of the infrared light generated by an LED chip travels towards the light extraction surface, but some infrared light may travel in a different direction. For example, there may be infrared light emitted from the side of the LED chip that travels along the first surface of the substrate. Here, when we say that infrared light "travels along the first surface of the substrate," we do not mean that it "travels in a direction parallel to the first surface of the substrate," but rather that the vector component parallel to the first surface of the substrate is larger than the vector component perpendicular to the first surface of the substrate. In short, infrared light emitted from the side of the LED chip spreads out in a direction parallel to the first surface of the substrate, with some of it traveling towards the light extraction surface and other parts traveling towards the first surface of the substrate.

[0017] Of the infrared light emitted from the side of the LED chip, the former is directed towards the light extraction surface, so it can be guided to the utilization optical system by, for example, installing an optical system at a later stage to focus the light. On the other hand, the latter is directed towards the first surface of the substrate, so it cannot be directed towards the light extraction surface and therefore cannot be guided to the utilization optical system.

[0018] In contrast, with the LED package structure described above, a region (first light reflection region) made of a material with higher reflectivity to infrared light than the substrate is formed on the first surface of the substrate, i.e., the surface on which the LED chip is mounted, outside the LED chip. Therefore, even infrared light that is emitted from the side of the LED chip and travels toward the first surface of the substrate can be reflected by the first light reflection region and guided toward the light extraction surface. This improves the light extraction efficiency.

[0019] Incidentally, in the LED package with the above structure, each of the pair of first conductive regions formed on the first surface of the substrate is individually connected to a pair of electrodes (anode electrode and cathode electrode) of the LED chip via a conductive bonding member. On the second surface of the substrate, opposite to the first surface, a pair of second conductive regions are formed at mutually separated positions, and the pair of first conductive regions and the pair of second conductive regions are connected by a pair of through electrodes that penetrate the substrate at different locations. Therefore, by bringing the second surface of the substrate into contact with a predetermined energizing region at the installation location of the LED package, a voltage can be applied to the LED chip from the second surface side of the substrate via the pair of through electrodes and the pair of first energizing regions. In other words, with the LED package with the above configuration, bonding wires for energization are unnecessary.

[0020] If infrared light is emitted from the side of the LED chip and travels toward the first surface of the substrate, and a bonding wire is present, this bonding wire may be in the path of the infrared light. Therefore, even if a reflector is provided on the first surface of the substrate, the amount of light incident on the reflector and the amount of infrared light reflected by the reflector may be reduced due to the presence of the bonding wire.

[0021] In contrast, as described above, by using a package that does not require bonding wires, bonding wires are no longer present in the optical path from when infrared light emitted from the side of the LED chip reaches the first light reflection region formed in the area outside the LED chip on the first surface of the substrate, nor in the optical path from when the light is reflected in the first light reflection region and travels towards the light extraction surface. As a result, the light extraction efficiency can be increased.

[0022] Furthermore, with the LED package structure described above, bonding wires are unnecessary, eliminating the need to allocate space for routing them. As a result, a smaller, lower-profile LED package can be realized.

[0023] The material constituting the substrate is selected from materials that have insulating properties and preferably high thermal conductivity. Typically, the substrate is composed of aluminum nitride. Other examples of materials constituting the substrate include ceramics such as aluminum oxide, zirconium oxide, silicon oxide, silicon carbide, and silicon nitride, as well as resin-containing materials such as glass epoxy (a material made by solidifying a glass fiber laminate with epoxy resin), polyamide resins, and polyimide resins. Furthermore, the substrate may consist of a mixture of two or more of the materials listed above, or a small amount of other substances may be mixed in addition to the listed materials (main substances).

[0024] The first light-reflecting region is made of a material that has higher reflectivity to infrared light than the substrate. Typically, the first light-reflecting region is made of a metallic material. In this case, it is preferable that the outer edge of the first light-reflecting region is located further inward and spaced further away from the outer edge of the first surface of the substrate. This prevents short circuits.

[0025] The first conductive region is made of a material containing Au, and extends outward from the LED chip when viewed from the side of the first surface of the substrate in the direction normal to the first surface. The first light reflection region may be formed in part by the first conductive region.

[0026] As described above, the infrared light has a peak wavelength of 1,000 nm to 2,000 nm. As a result of the inventors' diligent research, it has been confirmed that materials containing Au have a higher reflectivity for infrared light in this wavelength range compared to their reflectivity for ultraviolet and blue light. Therefore, even when the first light reflection region is formed with a material containing Au, there is a high effect in reflecting the infrared light traveling toward the first surface of the substrate toward the light extraction surface.

[0027] Furthermore, since Au is a highly stable material, it is less susceptible to degradation due to oxidation, etc., even when formed on the first surface of the substrate. Therefore, by extending a portion of the first conductive region for conducting electricity through the substrate to the outside of the LED chip, it is possible to combine the functions of conducting electricity and reflecting infrared light. Methods for forming the first conductive region made of Au-containing material include plating, vapor deposition, and sputtering, with plating being the most common method.

[0028] As an example, the first conductive region may be formed as a continuous extension in the direction from the outer edge of the LED chip toward the outer edge of the first surface of the substrate, when viewed from the side of the first surface of the substrate in the direction normal to the first surface.

[0029] The aforementioned LED chip is Semiconductor substrate and A semiconductor laminate is formed on the upper layer of the first substrate surface, which is one of the main surfaces of the semiconductor substrate, and comprises an n-type or p-type first semiconductor layer, an active layer that generates infrared light, and a second semiconductor layer with a conductivity different from that of the first semiconductor layer, which are stacked in order from the side closest to the first substrate surface. A first electrode, which constitutes one of the anode electrode and the cathode electrode, is formed in contact with at least a portion of the upper surface of the first semiconductor layer that is exposed when the second semiconductor layer and the active layer relating to a portion of the first substrate surface are excised in a direction perpendicular to the first substrate surface, as viewed in a direction parallel to the first substrate surface, With respect to the direction parallel to the first substrate surface, in a region spaced apart from the first electrode, the second electrode is formed in contact with at least a portion of the upper surface of the second semiconductor layer, and constitutes the other of the anode electrode and the cathode electrode, The semiconductor laminate has an in-chip reflective layer formed on the upper layer on the side away from the semiconductor substrate, which reflects the infrared light emitted from the active layer toward the side away from the semiconductor substrate toward the side of the semiconductor substrate, The first electrode and the chip-internal reflection layer are formed spaced apart in a direction parallel to the first substrate surface. The LED package may further include a second light-reflecting region, which is formed in at least a portion of the region on the first surface of the substrate, directly below the region sandwiched between the first electrode and the chip-internal reflective layer, when viewed from the side of the first surface of the substrate in the direction normal to the first surface, and is made of a material with higher reflectivity to infrared light than the substrate.

[0030] With the above configuration, much of the infrared light emitted from the active layer and traveling through the semiconductor stack toward the substrate can be reflected by the chip-internal reflective layer and directed toward the light extraction surface. The chip-internal reflective layer preferably has a reflectivity of 70% or more for infrared light, more preferably 80% or more, and particularly preferably 90% or more. As such a material, metallic materials such as Ag, Ag alloy, Au, Al, and Cu can be used, and two or more of these materials may be included.

[0031] Some infrared light emitted from the active layer and traveling through the semiconductor stack toward the substrate may travel toward the first surface of the substrate without being incident on the chip-internal reflective layer. However, with the above structure, a second light reflection region is formed on the first surface of the substrate, in at least a portion of the region directly below the area sandwiched between the first electrode and the chip-internal reflective layer when viewed from the first surface side in the direction normal to the first surface. Therefore, infrared light traveling through the semiconductor stack toward the substrate and traveling toward the first surface of the substrate without being incident on the chip-internal reflective layer can be reflected toward the light extraction surface by this second light reflection region. This further enhances the light extraction efficiency.

[0032] The second light reflection region may be formed by the conductive bonding member or the first conductive region.

[0033] The conductive bonding member is typically composed of solder material. Typical solder materials used include Sn-Ag-Cu solder (solder containing Sn, Ag, and Cu, sometimes referred to as "SAC solder"). Other examples of materials that constitute the conductive bonding member include various solder materials such as Sn-Cu solder, Sn-Sb solder, Sn-Bi solder, and Au-Sn solder, as well as bonding materials in which metal particles are dispersed in a resin, such as silver paste and gold paste. The conductive bonding member may consist of a mixture of two or more of the materials listed above, or a small amount of other substances may be mixed in addition to the listed materials (main substances).

[0034] As a result of the inventor's diligent research, it has been confirmed that the solder material has a significantly higher reflectivity for infrared light with a peak wavelength of 1,000 nm to 2,000 nm compared to its reflectivity for ultraviolet and blue light. Therefore, by positioning the conductive bonding member so that it is located directly below the region sandwiched between the first electrode and the chip's internal reflective layer when viewed from the first surface in the direction normal to the first surface, the effect of reflecting infrared light that travels toward the first surface of the substrate without entering the chip's internal reflective layer toward the light extraction surface is achieved.

[0035] Furthermore, by exposing a portion of the first conductive region directly below the area sandwiched between the first electrode and the chip's internal reflective layer when viewed from the first surface in the direction normal to the first surface, the first conductive region can also function as a second light-reflecting region.

[0036] The first light reflection region comprises an anode-side first light reflection region located closer to the anode electrode than the cathode electrode when viewed from the side of the first surface of the substrate in the direction normal to the first surface, and a cathode-side first light reflection region formed spaced apart from the anode-side first light reflection region and located closer to the cathode electrode than the anode electrode. When viewed from the side of the first surface of the substrate in the direction normal to the first surface, the anode-side first light reflection region and the cathode-side first light reflection region may differ from each other in at least one of their shapes and areas.

[0037] With the above configuration, when a consumer installs the LED package at a location of use, they can easily recognize which side is the anode and which is the cathode by visually observing the shape and size of the area of ​​metallic material formed outside the LED chip on the first surface of the substrate, i.e., the first light reflection area, when looking at the first surface from the side where the LED chip is attached. This reduces the risk of accidentally reversing the polarity when installing the LED package.

[0038] When viewed from the side of the second surface of the substrate in the direction normal to the second surface, the pair of second conductive regions may differ from each other in at least one of their shape and area.

[0039] With the above configuration, when a user installs the LED package at a location, they can easily recognize which side is the anode and which is the cathode, even when viewing the second side of the substrate from the opposite side of where the LED chip is attached. This reduces the risk of accidentally reversing the polarity when installing the LED package.

[0040] When viewed from the side of the first surface of the substrate in the direction normal to the first surface, the ratio (S2 / S1) of the area S2 of the first light reflection region located outside the LED chip to the area S1 of the first surface located outside the LED chip may be in the range of 30% to 90%. Preferably, the ratio is 40% or more, and particularly preferably 50% or more. The higher this ratio, the higher the proportion of infrared light emitted from the side of the LED chip and traveling toward the first surface of the substrate that can be reflected to the light extraction surface.

[0041] However, especially when the first light reflection region is made of a conductive material such as a metallic material, if the first light reflection region is formed near the outer edge of the first surface of the substrate, it may cause a short circuit with surrounding elements. In particular, if the first light reflection region is electrically connected to the anode electrode or cathode electrode of the LED chip, there is a concern that the LED chip will not light up due to the short circuit. From this viewpoint, it is preferable that the first light reflection region is formed in an area of ​​90% or less of the area of ​​the first surface located outside the LED chip when viewed from the side of the first surface of the substrate in the direction normal to the first surface.

[0042] The LED package may further include a sealing resin body formed on the first surface side of the substrate so as to cover the outer circumference of the LED chip.

[0043] When an LED chip emitting infrared light with a peak wavelength of 1,000 nm to 2,000 nm is mounted as a flip-chip, the InP substrate used as the base material for epitaxial growth of the semiconductor layer typically remains on the LED chip. Since the LED chip is mounted with the side where the semiconductor layer is formed facing the first surface of the substrate, the light extraction surface is the InP substrate side. When using infrared light with a wavelength of 1,000 nm to 2,000 nm as a reference, the refractive index of air is 1, while the refractive index of InP is a much larger value of approximately 3.1 to 3.3. Therefore, if infrared light that has passed through the InP substrate is extracted to the outside without any modification, the proportion of infrared light that undergoes total internal reflection at the interface of the InP substrate will increase.

[0044] In contrast, as shown in the structure above, by covering the outer circumference of the LED chip with a sealing resin, infrared light that has passed through the InP substrate is first incident within the sealing resin, passes through the resin, and then radiates to the outside. The refractive index of the sealing resin for infrared light with wavelengths of 1,000 nm to 2,000 nm depends on the material of the resin used, but is generally in the range of 1.2 to 2.0. Examples of resin materials include epoxy resin, silicone resin, and fluororesin, and mixtures of these materials are also acceptable. Therefore, the refractive index difference at the interface between the InP substrate and the sealing resin, and at the interface between the sealing resin and air, is lower than the refractive index difference at the interface between the InP substrate and air when the sealing resin is not present. Thus, the proportion of infrared light that has passed through the InP substrate and been returned by total internal reflection can be suppressed, and the light extraction efficiency can be increased.

[0045] A single LED chip is mounted on the first surface of the substrate. The sealing resin body may be formed to cover the outer circumference of a single LED chip.

[0046] With the above configuration, infrared light emitted from the side of the semiconductor substrate (typically an InP substrate) of the LED chip and traveling along the first surface of the substrate can also be extracted externally while suppressing total internal reflection. Furthermore, some of the reflected light that has been totally reflected can also be directed towards the light extraction surface. [Effects of the Invention]

[0047] According to the LED package of the present invention, infrared light emitted from the LED chip can be extracted to the outside with higher efficiency than in conventional methods. [Brief explanation of the drawing]

[0048] [Figure 1] This is a schematic cross-sectional view showing the structure of one embodiment of an LED package. [Figure 2] Figure 1 is a schematic cross-sectional view showing the structure of an LED chip mounted in an LED package. [Figure 3] This is a partially enlarged view of Figure 1. [Figure 4] This is a partially enlarged view of Figure 1. [Figure 5] This is a schematic plan view showing the structure of an LED chip, corresponding to the side that is fixed to the substrate. [Figure 6] This is a schematic plan view illustrating the shape of the first conductive region formed on the first surface of the substrate. [Figure 7] Figure 6 is a schematic plan view of the substrate with an LED chip mounted on its first surface, as seen from the LED chip side. [Figure 8] This is a schematic plan view illustrating the shape of the second conductive region formed on the second surface of the substrate. [Figure 9] This is a schematic plan view showing the LED chip mounted on the first surface of the substrate; for explanatory purposes, the first conductive region is omitted from the diagram. [Figure 10] This graph shows the diffuse reflectance of aluminum nitride, Sn-Ag-Cu solder, and Au at different wavelengths. [Figure 11] This is a schematic diagram illustrating the experimental method used to obtain the data shown in Figure 10. [Figure 12] This is a schematic plan view illustrating another shape of the first conductive region formed on the first surface of the substrate. [Figure 13] This is a schematic plan view illustrating another shape of the first conductive region formed on the first surface of the substrate. [Figure 14] This is a schematic plan view illustrating another shape of the first conductive region formed on the first surface of the substrate. [Figure 15] This is a schematic plan view illustrating another shape of the first conductive region formed on the first surface of the substrate. [Figure 16] This is a schematic plan view illustrating another shape of the first conductive region formed on the first surface of the substrate. [Figure 17] This is a schematic cross-sectional view showing the structure of another embodiment of the LED package. [Figure 18]This is a schematic partial cross-sectional view showing the structure of another embodiment of the LED package. [Figure 19] This is a schematic partial cross-sectional view showing the structure of another embodiment of the LED package. [Modes for carrying out the invention]

[0049] Embodiments of the LED package according to the present invention will be described below with reference to the drawings as appropriate. Note that the following drawings are schematic representations, and the dimensional ratios and number of elements shown in the drawings do not necessarily correspond to the actual dimensional ratios and number of elements.

[0050] In this specification, the expression "layer B is formed on top of layer A" is intended to include not only cases where layer B is formed directly on the surface of layer A, but also cases where layer B is formed on the surface of layer A via a thin film. Here, "thin film" refers to a layer with a thickness of 50 nm or less, preferably a layer with a thickness of 10 nm or less.

[0051] Furthermore, within this specification, the expression "layer B is formed on top of layer A" is not limited to layer B being located vertically above layer A, but includes cases where layer B is positioned above layer A when the LED chip containing layers A and B, or the LED package on which this LED chip is mounted, is rotated appropriately.

[0052] In this specification, the notation "GaInAsP" means a mixed crystal of Ga, In, As, and P, and simply omits the description of the composition ratio. The same applies to other notations such as "AlGaInAs".

[0053] Figure 1 is a schematic cross-sectional view showing the structure of one embodiment of an LED package. As shown in Figure 1, the LED package 1 comprises a substrate 7, an LED chip 3 mounted on the substrate 7, and a sealing resin body 5 covering the outer periphery of the LED chip 3. The LED chip 3 is flip-chip mounted on the substrate 7.

[0054] More specifically, the LED chip 3 is fixed to the first surface 7a of the substrate 7 by conductive bonding members 8 and 9. In this embodiment, the conductive bonding members 8 and 9 are made of solder material, and are typically Sn-Ag-Cu solder (solder containing Sn, Ag, and Cu). Other materials that can be used as conductive bonding members 8 and 9 include various solder materials such as Sn-Cu solder, Sn-Sb solder, Sn-Bi solder, and Au-Sn solder, as well as bonding materials in which metal particles are dispersed in resin, such as silver paste and gold paste. The conductive bonding members 8 and 9 may consist of a mixture of two or more of the materials listed above, or a small amount of other substances may be mixed in addition to the materials listed above (main substances).

[0055] LED chip 3 is configured to emit infrared light with a peak wavelength of 1,000 nm to 2,000 nm. An example of the detailed structure of LED chip 3 will be described later with reference to Figure 2.

[0056] The sealing resin body 5 is provided for the purpose of suppressing the proportion of infrared light emitted from the LED chip 3 that is totally reflected back to the LED chip 3. Examples of materials that make up the sealing resin body 5 include epoxy resin, silicone resin, fluororesin, etc., and a mixture of these materials may also be used.

[0057] The substrate 7 serves both the function of mounting the LED chip 3 and the function of dissipating heat from the LED chip 3. From this viewpoint, the substrate 7 is preferably made of a material with relatively high thermal conductivity and rigidity. However, since the LED chip 3 is an element that emits light when a voltage is applied between the anode electrode and the cathode electrode, a short circuit between the two electrodes must be avoided. Therefore, the substrate 7 is required to be made of an insulating material. From this viewpoint, aluminum nitride is typically used as the material for the substrate 7. Other examples of materials that constitute the substrate 7 include ceramics such as aluminum oxide, zirconium oxide, silicon oxide, silicon carbide, and silicon nitride, as well as resin-containing materials such as glass epoxy (a material made by solidifying a glass fiber laminate with epoxy resin), polyamide resins, and polyimide resins. The substrate 7 may be made of a mixture of two or more of the materials listed above, or a small amount of other substances may be mixed in addition to the materials listed above (main substances).

[0058] Figure 2 is a schematic cross-sectional view showing the structure of the LED chip 3 in Figure 1. The LED chip 3 has a semiconductor substrate 11 and a semiconductor laminate 12 formed on the semiconductor substrate 11, which includes a first semiconductor layer 13, an active layer 14, and a second semiconductor layer 15.

[0059] The semiconductor substrate 11 is typically an InP substrate. The semiconductor substrate 11 is also used as a base material for epitaxial growth of the semiconductor laminate 12. The thickness of the semiconductor substrate 11 is preferably 20 μm to 1,000 μm, and more preferably 50 μm to 700 μm.

[0060] The first semiconductor layer 13 is formed on the upper layer of one main surface (first substrate surface 11a) of the semiconductor substrate 11. In this embodiment, the first semiconductor layer 13 is composed of n-type InP. The thickness of the first semiconductor layer 13 is not limited, but is, for example, 1,000 nm to 20,000 nm, and preferably 3,000 nm to 10,000 nm. The dopant concentration of the first semiconductor layer 13 is preferably 1 × 10⁻¹⁶ 17 / cm 3 ~5×10 18 / cm 3 And more preferably, 5 × 10 17 / cm 3 ~4×10 18 / cm 3 The n-type dopant material included in the first semiconductor layer 13 can be Sn, Si, S, Ge, Se, etc., with Si being particularly preferred.

[0061] The active layer 14 is formed on the upper layer of the first semiconductor layer 13 (on the side away from the semiconductor substrate 11). More specifically, the active layer 14 is formed on the upper layer of a portion of the first semiconductor layer 13.

[0062] The active layer 14 is appropriately selected from materials that can generate light of the target wavelength and can be epitaxially grown in lattice matching with the semiconductor substrate 11. For example, the semiconductor substrate 11 may be a single-layer structure of GaInAsP, AlGaInAs, or InGaAs, or it may be an MQW (Multiple Quantum Well) structure including a well layer made of GaInAsP, AlGaInAs, or InGaAs and a barrier layer made of GaInAsP, AlGaInAs, InGaAs, or InP having a larger bandgap energy than the well layer. The active layer 14 may be n-type or p-type doped, or undoped. If it is n-type doped, for example, Si can be used as a dopant.

[0063] The thickness of the active layer 14 is 50 nm to 2,000 nm, preferably 100 nm to 1,000 nm, when the active layer 14 has a single-layer structure. When the active layer 14 has an MQW structure, it is constructed by stacking well layers and barrier layers with thicknesses of 2 nm to 20 nm in a range of 2 to 50 periods.

[0064] The second semiconductor layer 15 is formed on the upper layer of the active layer 14 (on the side away from the semiconductor substrate 11). In this embodiment, the second semiconductor layer 15 is composed of a p-type semiconductor layer and includes a p-type cladding layer and a p-type contact layer.

[0065] Of the second semiconductor layer 15, the p-type cladding layer is made of, for example, p-type InP. The thickness of this p-type cladding layer is not limited, but is, for example, 1,000 nm to 10,000 nm, preferably 2,000 nm to 5,000 nm. The p-type dopant concentration of the p-type cladding layer is preferably 1×10 17 / cm 3 ~3×10 18 / cm 3 at a position away from the active layer 14, and more preferably 5×10 17 / cm 3 ~3×10 18 / cm 3 or less.

[0066] Of the second semiconductor layer 15, the p-type contact layer is made of, for example, p-type GaInAsP. The thickness of this p-type contact layer is not limited, but is, for example, 10 nm to 1,000 nm, preferably 50 nm to 500 nm. Also, the p-type dopant concentration of the p-type contact layer is preferably 5×10 17 / cm<000001⑧>~3×10 19 / cm 3 or less, and more preferably 1×10 18 / cm 3 ~2×10 19 / cm 3 or less.

[0067] As the p-type dopant material included in the p-type cladding layer and the p-type contact layer constituting the second semiconductor layer 15, Zn, Mg, Be, etc. can be used, Zn or Mg is preferable, and Zn is particularly preferable. <0◦00312> The first semiconductor layer 13 and the second semiconductor layer 15 are materials that do not absorb the infrared light generated in the active layer 14, and are appropriately selected from materials that are lattice-matched with the semiconductor substrate 11 and can be epitaxially grown. For example, as the first semiconductor layer 13 and the second semiconductor layer 15, in addition to InP, materials such as GaInAsP and AlGaInAs can be used.

[0069] In this embodiment, the case in which the second semiconductor layer 15 has a laminated structure of a cladding layer and a contact layer has been described, but the present invention does not exclude the case in which the cladding layer and the contact layer have the same material. Furthermore, the present invention does not exclude the case in which the first semiconductor layer 13 is composed of a laminate of cladding layers and contact layers with different materials and dopant concentrations.

[0070] As shown in Figure 2, in the semiconductor laminate 12, a portion of the structure is excavated in a direction perpendicular to the first substrate surface 11a, thereby removing the second semiconductor layer 15 and the active layer 14, leaving the first semiconductor layer 13 at the top. The LED chip 3 includes a first electrode 21 positioned to contact the first semiconductor layer 13 within this region.

[0071] The first electrode 21 is connected to the first semiconductor layer 13 by an ohmic connection. The first electrode 21 is composed of materials such as Au / Ge / Au, Au / Ge / Ni / Au, AuGe, and AuGeNi, and may also consist of multiple such materials. The thickness of the first electrode 21 is not limited, but is, for example, 50 nm to 500 nm, and preferably 100 nm to 300 nm.

[0072] The LED chip 3 includes a second electrode 22 formed in contact with the second semiconductor layer 15. The second electrode 22 is formed at a position spaced apart from the first electrode 21 in a direction parallel to the first substrate surface 11a. Furthermore, as will be described later with reference to Figure 5, the second electrodes 22 are dispersed in a direction parallel to the first substrate surface 11a. An insulating layer 17 is formed between adjacent second electrodes 22. More specifically, the multiple second electrodes 22 dispersed in a direction parallel to the first substrate surface 11a are arranged to be embedded within the insulating layer 17. The insulating layer 17 covers the second semiconductor layer 15, the active layer 14, and a portion of the sidewalls of the first semiconductor layer 13 in the vicinity of the first electrode 21.

[0073] The insulating layer 17 is made of a material that exhibits electrical insulation properties and has high transmittance to infrared light L generated in the active layer 14. The transmittance of the insulating layer 17 to infrared light L is preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more. Materials such as SiO2, SiN, and Al2O3 can be used as the insulating layer 17.

[0074] The second electrode 22 is made of a material capable of ohmic contact with the second semiconductor layer 15. For example, the second electrode 22 is made of materials such as Au / Zn / Au, AuZn, or AuBe, and may comprise multiple such materials. As described above, if the second semiconductor layer 15 includes a contact layer, ohmic contact is formed between this contact layer and the second electrode 22. The thickness of the second electrode 22 is not limited, but is, for example, 50 nm to 500 nm, preferably 100 nm to 300 nm.

[0075] As shown in Figure 2, the LED chip 3 of this embodiment is provided with an internal chip reflective layer 23 on the upper layer (the side away from the semiconductor substrate 11) of the second electrode 22. The internal chip reflective layer 23 has the function of returning the infrared light L generated in the active layer 14, which has traveled toward the second semiconductor layer 15 and passed through the insulating layer 17, back toward the semiconductor substrate 11. The internal chip reflective layer 23 is made of a conductive material that exhibits a high reflectivity to infrared light L. The reflectivity of the internal chip reflective layer 23 to infrared light L1 is preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more.

[0076] The second electrode 22 needs to achieve ohmic contact with the second semiconductor layer 15, and is therefore made of a material that can be easily alloyed with the second semiconductor layer 15 (more specifically, the contact layer) to achieve low contact resistance. For this reason, as mentioned above, the second electrode 22 can be made of AuZn, AuBe, or an Au / Zn / Au layer structure. However, these materials have relatively low reflectivity to infrared light L. Therefore, if the second electrode 22 is formed across the entire surface of the second semiconductor layer 15, the proportion of infrared light L generated in the active layer 14 and propagating towards the second semiconductor layer 15 that is absorbed by the second electrode 22 becomes high.

[0077] In contrast, in the LED chip 3 of this embodiment, the second electrode 22 is discretely arranged on the upper layer of the second semiconductor layer 15, and an insulating layer 17 made of a material that exhibits high transmittance to infrared light L is formed in the region of the upper layer of the second semiconductor layer 15 where the second electrode 22 is not formed. Above this insulating layer 17, an in-chip reflective layer 23 is formed made of a material with a higher reflectivity to infrared light L than the second electrode 22. As a result, a portion of the infrared light L generated in the active layer 14 and traveling toward the second semiconductor layer 15 is not absorbed by the second electrode 22, but travels through the insulating layer 17, enters the in-chip reflective layer 23, is reflected by the in-chip reflective layer 23, and is guided toward the semiconductor substrate 11. As a result, the light extraction efficiency is increased. Since the in-chip reflective layer 23 does not come into contact with the second semiconductor layer 15, it does not need to be made of a material that can achieve ohmic contact with the second semiconductor layer 15, and can be selected and used from among metal materials with a higher reflectivity than the second electrode 22. Specifically, the chip's internal reflective layer 23 can be made of metallic materials such as Ag, Ag alloy, Au, Al, Cu, or Al / Au.

[0078] The thickness of the chip's internal reflective layer 23 is not particularly limited, but is, for example, 10 nm to 2,000 nm, and preferably 100 nm to 1,000 nm.

[0079] As shown in Figure 2, the LED chip 3 comprises a first pad electrode 24 formed on the upper layer of the first electrode 21 and a second pad electrode 25 formed on the upper layer of the chip's internal reflective layer 23. In the example shown in Figure 2, an insulating layer 18 is formed to cover the area on the upper surface of the chip's internal reflective layer 23 where the second pad electrode 25 is not formed. The insulating layer 18 may be made of the same material as the insulating layer 17.

[0080] The first pad electrode 24 and the second pad electrode 25 each form a region that comes into contact with the conductive bonding members 8 and 9. The first pad electrode 24 and the second pad electrode 25 are composed of, for example, Ti / Au, Ti / Pt / Au, etc. The thickness of the first pad electrode 24 and the second pad electrode 25 is not particularly limited, but is, for example, 500 nm to 5,000 nm, and preferably 1,000 nm to 4,000 nm.

[0081] As shown in Figure 2, the LED chip 3 of this embodiment has a textured surface on the main surface (second substrate surface 11b) opposite to the first substrate surface 11a of the semiconductor substrate 11. Preferably, the arithmetic mean roughness Ra of the second substrate surface 11b is 10 nm or more, and more preferably 100 nm or more. By applying such textured processing to the second substrate surface 11b, the proportion of infrared light L1 generated in the active layer 14 and propagating toward the semiconductor substrate 11 that undergoes total internal reflection at the surface of the semiconductor substrate 11 is reduced, thereby improving the light extraction efficiency.

[0082] Furthermore, the LED chip 3 of this embodiment is provided with a light-transmitting layer 27 made of a material with high transmittance to infrared light L on the second substrate surface 11b of the semiconductor substrate 11. This light-transmitting layer 27 is selected from a material that has a transmittance of 80% or more to infrared light L and a refractive index between that of the semiconductor substrate 11 and the sealing resin 5. Specifically, the light-transmitting layer 27 is made of SiO x ,SiON,SiN x , TiO x MgO x These materials can be used, and multiple combinations of these materials are acceptable.

[0083] By providing such a light-transmitting layer 27 in the LED chip 3, the proportion of infrared light L that is totally reflected at the second substrate surface 11b of the semiconductor substrate 11 is further reduced, and the light extraction efficiency is further improved. When infrared light L with a wavelength of 1,000 nm to 2,000 nm is used as a reference, the refractive index of air is 1, while the refractive index of InP, a typical material for the semiconductor substrate 11, is a large value of about 3.1 to 3.3. Therefore, by compensating for the refractive index difference between the semiconductor substrate 11 and air with the light-transmitting layer 27 and the sealing resin 5, the passage of infrared light L through the interface of the two materials with a large refractive index difference is suppressed. As a result, the proportion of total reflection at the interface is reduced, and the light extraction efficiency can be greatly increased. However, this invention does not exclude semiconductor substrates 11 that do not have a textured surface on the second substrate surface 11b or that do not have a light-transmitting layer 27 on the upper surface of the second substrate surface 11b.

[0084] Figures 3 and 4 are enlarged views of parts of Figure 1, respectively. More specifically, Figure 3 is an enlarged view of the side of the first electrode 21 of the LED package 1 shown in Figure 1, and Figure 4 is an enlarged view of the side of the second electrode 22 of the LED package 1 shown in Figure 1.

[0085] As described above, some of the infrared light generated in the active layer 15 travels towards the semiconductor substrate 11 and is extracted to the outside (infrared light L1). Another portion of the infrared light generated in the active layer 15 travels away from the semiconductor substrate 11, is reflected by the chip's internal reflection layer 23, and then travels towards the semiconductor substrate 11 and is extracted to the outside (infrared light L2).

[0086] As shown in Figures 3 and 4, first conductive regions 31 and 36 are formed on the first surface 7a of the substrate 7, and second conductive regions 32 and 37 are formed on the second surface 7b opposite to the first surface 7a. The first conductive region 31 is connected to the first pad electrode 24 via a conductive bonding member 8. The first conductive region 36 is connected to the second pad electrode 25 via a conductive bonding member 9. The first conductive regions 31 and 36 are made of a metallic material, preferably a material exhibiting high oxidation resistance. Typically, the first conductive regions 31 and 36 are made of a material containing Au, such as Ti / Au. Other materials that constitute the first conductive regions 31 and 36 include Ti / Pd / Au, Ti / Ag-Cu / Au, and Mo-Mn / Ni / Au. The second conductive regions 32 and 37 can be made of the same material as the first conductive regions 31 and 36.

[0087] The substrate 7 has embedded through electrodes 33 and 38 that connect the first surface 7a and the second surface 7b internally. More specifically, the through electrode 33 electrically connects the first conductive region 31 and the second conductive region 32, which correspond to the first electrode 21 side, and the through electrode 38 electrically connects the first conductive region 36 and the second conductive region 37, which correspond to the second electrode 22 side. Since the through electrodes 33 and 38 are not exposed, low resistivity is prioritized over oxidation resistance when selecting the constituent material for the through electrodes 33 and 38. From this viewpoint, Cu is typically used as the constituent material for the through electrodes 33 and 38. Other examples of constituent materials for the through electrodes 33 and 38 include Cu-W, Al, Fe-Ni-Co, etc.

[0088] This allows the second surface 7b of the substrate 7 to be installed at the location where the LED package 1 will be used, and power to the LED chip 3 can be supplied from the second surface 7b side of the substrate 7. In this embodiment, the first electrode 21 and the first pad electrode 24 form the "cathode electrode" of the LED chip 3, and the second electrode 22 and the second pad electrode 25 form the "anode electrode" of the LED chip 3. However, the conductivity types of the first semiconductor layer 13 and the second semiconductor layer 15 may be reversed, and accordingly, the "cathode electrode" and "anode electrode" in the above description will be reversed.

[0089] In the example shown in Figure 3, the first conductive region 31, which is formed on the first surface 7a of the substrate 7 and corresponds to the first electrode 21 side, extends outward from the LED chip 3 when viewed in the direction normal to the first surface 7a. As will be described later with reference to Figure 10, materials containing Au, such as Ti / Au, exhibit high reflectivity for infrared light with a peak wavelength of 1,000 nm to 2,000 nm. Therefore, infrared light L4 and L5, which are emitted from the side of the LED chip 3 (typically the side of the semiconductor substrate 11) and propagate toward the first surface 7a of the substrate 7 while spreading outward from the LED chip 3, can be reflected by the first conductive region 31 that extends outward from the LED chip 3 and directed toward the light extraction surface side (+Z direction).

[0090] In the example shown in Figure 4, the first conductive region 36, which is formed on the first surface 7a of the substrate 7 and corresponds to the second electrode 22 side, extends outward from the LED chip 3 when viewed in the direction normal to the first surface 7a. Therefore, similar to the case of the first conductive region 31, infrared light L4 and L5 that emits from the side of the LED chip 3 (typically the side of the semiconductor substrate 11) and spreads outward from the LED chip 3 while traveling toward the first surface 7a of the substrate 7 can be reflected by the first conductive region 36 that extends outward from the LED chip 3 and directed toward the light extraction surface side (+Z direction). In other words, in this embodiment, the first conductive regions 31 and 36 correspond to the "first light reflection region". More specifically, in this example, the first conductive region 31 corresponds to the "cathode side first light reflection region", and the first conductive region 36 corresponds to the "anode side first light reflection region".

[0091] As shown in Figures 3 and 4, on the first surface 7a of the substrate 7, the outer edges of the first conductive regions 31 and 36 are located inward from the outer edge of the substrate 7 (arrow da). This suppresses short circuits between products and other items placed around the LED package 1 and the first conductive region 31 or the first conductive region 36.

[0092] As will be described later with reference to Figure 10, solder materials such as SAC solder exhibit high reflectivity for infrared light with a peak wavelength of 1,000 nm to 2,000 nm. Therefore, as shown in Figure 3, by extending the conductive bonding member 8 to at least a portion of the region directly below the region sandwiched between the first electrode 21 and the chip-internal reflective layer 23 on the first surface 7a of the substrate 7, the infrared light L3 can be reflected by the conductive bonding member 8. More specifically, the infrared light L3 generated in the active layer 14 that passes through the insulating layers 17 and 18 located outside the chip-internal reflective layer 23 and travels toward the first surface 7a of the substrate 7 can be reflected by the conductive bonding member 8 and directed toward the light extraction surface side (+Z direction). In other words, in this embodiment, the conductive bonding member 8 corresponds to the "second light reflection region".

[0093] Figure 5 is a schematic plan view of the LED chip 3 as seen from the side fixed to the first surface 7a of the substrate 7. For ease of understanding, the first electrode 21 and the second electrode 22 are shown with dashed lines. As shown in Figure 5, the first pad electrode 24 and the second pad electrode 25 are spaced apart in the planar direction. As described above, multiple second electrodes 22 are arranged in a dispersed manner in the planar direction and are electrically connected to the second pad electrode 25 via the chip's internal reflective layer 23.

[0094] Figure 6 is a schematic plan view showing the first conductive regions 31 and 36 formed on the first surface 7a of the substrate 7. In the example shown in Figure 6, the first conductive region 31 on the first electrode 21 side and the first conductive region 36 on the second electrode 22 side have different shapes. This makes it possible to visually recognize which of the first conductive regions 31 and 36 corresponds to the anode side and which corresponds to the cathode side when mounting the LED chip 3 on the first surface 7a of the substrate 7.

[0095] Figure 7 is a schematic plan view of the LED chip 3 mounted on the first surface 7a of the substrate 7 shown in Figure 6, as seen from the LED chip 3 side. As described above with reference to Figure 6, the first conductive region 31 on the first electrode 21 side and the first conductive region 36 on the second electrode 22 side have different shapes. As a result, even after mounting the LED chip 3, the first conductive region 31 on the first electrode 21 side and the first conductive region 36 on the second electrode 22 side, which are exposed on the outside of the LED chip 3, have different shapes. This allows consumers to visually recognize which of the first conductive region 31 and first conductive region 36 corresponds to the anode side and which corresponds to the cathode side by detecting the shapes of the first conductive region 31 and first conductive region 36 when installing the LED package 1 at the place of use. Therefore, the risk of accidentally reversing the polarity when installing the LED package 1 is reduced.

[0096] Figure 8 is a schematic plan view showing the second conductive regions 32 and 37 formed on the second surface 7b of the substrate 7. In the example shown in Figure 8, the second conductive region 32 on the first electrode 21 side and the second conductive region 37 on the second electrode 22 side have different shapes. This allows consumers to visually recognize which of the second conductive regions 32 and 37 corresponds to the anode side and which corresponds to the cathode side when installing the LED package 1 at the intended location by detecting the shapes of the second conductive regions 32 and 37 formed on the second surface 7b of the substrate 7. Therefore, the risk of accidentally reversing the polarity when installing the LED package 1 is reduced.

[0097] Figure 9 is a schematic plan view showing the LED chip 3 mounted on the first surface 7a of the substrate 7, and for explanatory purposes, the first conductive regions 31 and 36 are omitted from the illustration. As described above with reference to Figures 3 and 4, the first conductive regions 31 and 36, which are formed extending to the outside of the LED chip 3, have the function of reflecting infrared light L4 and L5 that is emitted from the side of the LED chip 3 and propagates toward the first surface 7a of the substrate 7 while spreading outwards from the LED chip 3 toward the light extraction surface. From the viewpoint of improving the light extraction efficiency of the LED package 1, it is preferable to secure a large area for the first conductive regions 31 and 36 that extend to the outside of the LED chip 3.

[0098] More specifically, the following applies. As shown in Figure 9, S1 is the area of ​​the first surface 7a located outside the LED chip 3, viewed from the side of the first surface 7a of the substrate 7 in the direction normal to the first surface 7a (Z direction). Also, as shown in Figure 7, S2 is the total area of ​​the first conductive regions 31 and 36 located outside the LED chip 3, viewed from the side of the first surface 7a of the substrate 7 in the direction normal to the first surface 7a (Z direction) (i.e., corresponding to the total area of ​​the first light reflective regions). In this case, the ratio of area S2 to area S1, S2 / S1, is preferably 30% or more, more preferably 40% or more, and particularly preferably 50% or more.

[0099] Figure 10 is a graph showing the diffuse reflectance of aluminum nitride, Sn-Ag-Cu solder, and Au at different wavelengths. Figure 11 is a schematic diagram illustrating the experimental method used to obtain the data in Figure 10.

[0100] The experimental system 60 shown in Figure 11 comprises a test light source 61, a diffraction grating 63, apertures 64 and 65, an integrating sphere 66, and a light receiving unit 68. The experimental system 60 corresponds to the V-7200 ultraviolet-visible-near-infrared spectrophotometer manufactured by JASCO Corporation. Using this experimental system 60, a standard reflector plate (Spectralon (99% reflectivity)) manufactured by Labsfair Corporation is placed at the location of sample 67 as a reference sample, and test light L61 from the test light source 61 is incident to measure the wavelength-specific light intensity I at the light receiving unit 68. rNext, the measurement targets (aluminum nitride test specimen, Sn-Ag-Cu solder test specimen, and Au test specimen) were placed at the location of sample 67, and the light reception intensity I for each wavelength at the light receiving unit 68 was measured in the same manner. s The light intensity I detected under each object was measured, with the reflectance of the reference sample as the reference value. s And the light detection intensity I detected under the reference sample r Based on this, the relative reflectance values ​​of each object being measured were derived.

[0101] More specifically, if a is the ratio to the reflectance of the exposed area of ​​the sample 67 relative to the reflectance of the entire inner surface of the integrating sphere 66, and I0 is the light intensity of the test light L61 emitted from the test light source 61, then the diffuse reflectance R of the object being measured is... s This can be derived using the following formula.

[0102]

number

[0103] According to the results in Figure 10 obtained using the method described above, it was confirmed that aluminum nitride, a typical example of a constituent material of substrate 7, has a nearly constant diffuse reflectance regardless of the wavelength of light in the wavelength range of 400 nm or more. Au, a typical example of a constituent material of the first conductive regions 31 and 36, has a reflectance almost equivalent to that of aluminum nitride in the ultraviolet region, while its reflectance is significantly higher than that of aluminum nitride in the wavelength range of 1,000 nm to 2,000 nm. Sn-Ag-Cu solder, a typical example of a constituent material of conductive bonding members 8 and 9, has a higher reflectance in the wavelength range of 1,000 nm to 2,000 nm compared to the ultraviolet region, and this value is significantly higher than that of aluminum nitride.

[0104] From these results, it can be seen that the first conductive regions 31 and 36 can function as the "first light reflection region," and the conductive bonding member 8 can function as the "second light reflection region."

[0105] The shapes of the first conductive regions 31 and 36 formed on the first surface 7a of the substrate 7 can vary in various ways. In the example shown in Figure 6, when comparing the first conductive region 31 and the first conductive region 36, the first conductive region 31 appears to have a shape in which some corners have been cut off. As another example, as shown in Figure 12, a shape in which the corners of the first conductive region 31 are rounded can be adopted. As yet another example, as shown in Figure 13, the size of the first conductive region 31 can be made smaller than the first conductive region 36 to a degree that is visually noticeable.

[0106] Furthermore, as shown in Figure 14, a light-reflecting region 31a may be formed outside the first conductive region 31, separated from the first conductive region 31, and similarly, a light-reflecting region 36a may be formed outside the first conductive region 36, separated from the first conductive region 36. The light-reflecting regions 31a and 36a can be made of the same material as the first conductive regions 31 and 36, but since they are separated from the first conductive regions 31 and 36, they do not conduct electricity. For this reason, the regions indicated by reference numerals 31a and 36a are named "light-reflecting region 31a" and "light-reflecting region 36a". In this case, the light-reflecting regions 31a and 36a correspond to the "first light-reflecting region". Note that the portions of the first conductive regions 31 and 36 that extend outside the LED chip 3 also function as the "first light-reflecting region".

[0107] In the embodiment shown in Figure 14, comparing the light reflection region 31a and the light reflection region 36a as in Figure 6, the light reflection region 31a appears to have a shape in which a part of its corner is cut off. However, this shape is merely an example. The shapes of the light reflection region 31a and the light reflection region 36a can also be, for example, similar to the shapes of the first conductive regions 31 and 36 shown in Figures 12 and 13.

[0108] Furthermore, when light-reflecting regions 31a and 36a are formed outside the first conductive regions 31 and 36, the configuration shown in Figure 15 can also be adopted. In the example shown in Figure 15, on the first surface 7a of the substrate 7, the first conductive regions 31 and 36 are located inside the light-reflecting regions 31a and 36a in a direction perpendicular to the direction in which the light-reflecting regions 31a and 36a are separated (left-right direction of the paper) (up-down direction of the paper) (arrow d1).

[0109] Furthermore, as described above with reference to Figure 14, the light reflection regions 31a and 36a are located outside the first conductive regions 31 and 36, separated from the first conductive regions 31 and 36, and are not energized. Therefore, as shown in Figure 16, the light reflection region 31a and the light reflection region 36a may be connected.

[0110] [Alternative Embodiment] The following describes another embodiment of LED package 1.

[0111] (1) As shown in Figure 17, the light extraction surface 5a side of the sealing resin body 5 may be made into a lens shape. Although not shown in the figure, a case in which a part of the sealing resin body 5 is missing is also within the scope of the present invention.

[0112] Furthermore, LED packages 1 without the sealing resin body 5 are also within the scope of the present invention. However, from the viewpoint of further improving light extraction efficiency, it is preferable for the LED package 1 to include the sealing resin body 5.

[0113] <2> In the example described with reference to Figure 3, of the infrared light generated in the active layer 14, the infrared light L3 that passes through the insulating layers 17 and 18 located outside the chip's internal reflective layer 23 and travels toward the first surface 7a of the substrate 7 is reflected by the conductive bonding member 8 and travels toward the light extraction surface side (+Z direction). In this case, the conductive bonding member 8 corresponds to the "second light reflection region".

[0114] In contrast, as shown in Figure 18, the first conductive region 31 may be extended on the first surface 7a of the substrate 7 to at least a portion of the region directly below the region sandwiched between the first electrode 21 and the chip-internal reflective layer 23, thereby allowing the first conductive region 31 located in that region to function as a "second light reflection region." That is, infrared light L3 generated in the active layer 14 that passes through the insulating layers 17 and 18 located outside the chip-internal reflective layer 23 and travels toward the first surface 7a of the substrate 7 may be reflected by the first conductive region 31.

[0115] Figure 18 illustrates a case where, as in Figure 14, a light-reflecting region 31a is formed outside the first conductive region 31, and a part of the first conductive region 31 functions as a "second light-reflecting region." However, it goes without saying that, as shown in Figure 3, the case where the first conductive region 31 extends continuously outward is also possible. In this case, the first conductive region 31 functions as a "first light-reflecting region" at a location outside the LED chip 3, and functions as a "second light-reflecting region" at a location directly below the region sandwiched between the first electrode 21 and the chip-internal reflective layer 23.

[0116] The present invention does not exclude the case in which the substrate 7 is exposed at a position directly below the region sandwiched between the first electrode 21 and the chip-internal reflective layer 23, as shown in Figure 19. However, in this case, infrared light L6 generated in the active layer 14 that passes through the insulating layers 17 and 18 located outside the chip-internal reflective layer 23 and travels toward the first surface 7a of the substrate 7 is absorbed by the substrate 7 at a predetermined rate when it is incident on the first surface 7a of the substrate 7. Therefore, from the viewpoint of further improving the light extraction efficiency, it is preferable to form a conductive bonding member 8 or a first conductive region 31 at a position directly below the region sandwiched between the first electrode 21 and the chip-internal reflective layer 23.

[0117] (3) The present invention is not limited to the embodiments described above, and includes various modifications. For example, the embodiments described above are described in detail for a better understanding of the present invention and are not necessarily limited to all configurations described. The scope of the present invention is indicated by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0118] 1: LED package 3: LED chip 5: Sealing resin body 5a: Light extraction surface 7: Base 7a: First surface of the substrate 7b: Second surface of the substrate 8: Conductive bonding member 9: Conductive bonding member 11: Semiconductor substrates 11a: First substrate surface of semiconductor substrate 11b: Second substrate surface of semiconductor substrate 12: Semiconductor Stack 13: First Semiconductor Layer 14:Active layer 15: Second semiconductor layer 17: Insulating layer 18: Insulating layer 21:First electrode 22:Second electrode 23: Reflective layer inside the chip 24: First pad electrode 25: Second pad electrode 27:Transparent layer 31:First conductive region 31a: Light reflective area 32:Second conductive region 33:Through electrode 36:First conductive region 36a: Light reflective area 37:Second conductive region 38:Through electrode 60: Experimental System 61: Test light source 63: Diffraction grating 64: Aperture 65: Aperture 66: Integrating sphere 67: Sample 68: Light receiving part L: Infrared light L1: Infrared light L3: Infrared light L4: Infrared light L5: Infrared light L6: Infrared light L61: Test light S1: Area S2: Area

Claims

1. An LED package including an LED chip that emits infrared light with a peak wavelength of 1,000 nm to 2,000 nm, The LED chip is mounted in a flip-chip configuration on a substrate made of an insulating material, A pair of first conductive regions, each consisting of a first conductive region on the anode electrode side and a first conductive region on the cathode electrode side, are formed spaced apart from each other on the first surface of the substrate on the LED chip side and each separately contacts the anode electrode and cathode electrode of the LED chip via a conductive bonding member, respectively. A pair of through electrodes, each consisting of a through electrode on the anode side and a through electrode on the cathode side, which penetrate the substrate at mutually separated positions and are formed to contact the pair of first conductive regions separately, A pair of second conductive regions are formed on the second surface of the substrate opposite to the first surface, spaced apart from each other, and in separate contact with the pair of through electrodes, each consisting of a second conductive region on the anode electrode side and a second conductive region on the cathode electrode side. An LED package characterized by comprising: a first light-reflecting region formed on the first surface of the substrate at a position outside the LED chip, as viewed from the side of the first surface of the substrate in the direction normal to the first surface, and made of a material with higher reflectivity to infrared light than the substrate.

2. The aforementioned first light reflection region is made of a metallic material. The LED package according to claim 1, characterized in that the outer edge of the first light reflection region is located at a position spaced inward from the outer edge of the first surface of the substrate.

3. The first conductive region is made of a material containing Au, and extends outward from the LED chip when viewed from the side of the first surface of the substrate in the direction normal to the first surface. The LED package according to claim 2, characterized in that at least a portion of the first light-reflecting region is formed by the first conductive region.

4. The LED package according to claim 3, characterized in that the first conductive region is formed to extend continuously in the direction toward the outer edge of the LED chip toward the outer edge of the first surface of the substrate, when viewed from the side of the first surface of the substrate in the direction normal to the first surface.

5. The aforementioned LED chip is Semiconductor substrate and A semiconductor laminate is formed on the upper layer of the first substrate surface, which is one of the main surfaces of the semiconductor substrate, and comprises an n-type or p-type first semiconductor layer, an active layer that generates infrared light, and a second semiconductor layer with a conductivity different from that of the first semiconductor layer, which are stacked in order from the side closest to the first substrate surface. A first electrode, which constitutes one of the anode electrode and the cathode electrode, is formed in contact with at least a portion of the upper surface of the first semiconductor layer that is exposed when the second semiconductor layer and the active layer relating to a portion of the first substrate surface are excised in a direction perpendicular to the first substrate surface, as viewed in a direction parallel to the first substrate surface, With respect to the direction parallel to the first substrate surface, in a region spaced apart from the first electrode, the second electrode is formed in contact with at least a portion of the upper surface of the second semiconductor layer, and constitutes the other of the anode electrode and the cathode electrode, The semiconductor laminate has an in-chip reflective layer formed on the upper layer on the side away from the semiconductor substrate, which reflects the infrared light emitted from the active layer toward the side away from the semiconductor substrate toward the side of the semiconductor substrate, The first electrode and the chip-internal reflection layer are formed spaced apart in a direction parallel to the first substrate surface. The LED package according to claim 3, further comprising a second light-reflecting region formed in at least a portion of the region on the first surface of the substrate, directly below the region sandwiched between the first electrode and the chip-internal reflective layer, as viewed from the side of the first surface of the substrate in the direction normal to the first surface, and made of a material with higher reflectivity to infrared light than the substrate.

6. The LED package according to claim 5, characterized in that the second light-reflecting region is formed by the conductive bonding member or the first conductive region.

7. The first light reflection region comprises an anode-side first light reflection region located closer to the anode electrode than the cathode electrode when viewed from the side of the first surface of the substrate in the direction normal to the first surface, and a cathode-side first light reflection region formed spaced apart from the anode-side first light reflection region and located closer to the cathode electrode than the anode electrode. The LED package according to claim 1, characterized in that, when viewed from the side of the first surface of the substrate in the direction normal to the first surface, at least one of the shape and area of ​​the anode-side first light reflection region and the cathode-side first light reflection region are different from each other.

8. The LED package according to claim 7, characterized in that, when viewed from the side of the second surface of the substrate in the direction normal to the second surface, the pair of second conductive regions differ from each other in at least one of their shape and area.

9. The LED package according to claim 1, characterized in that, when viewed from the side of the first surface of the substrate in the direction normal to the first surface, the ratio of the area of ​​the first light-reflecting region located outside the LED chip to the area of ​​the first surface located outside the LED chip is in the range of 30% to 90%.

10. The LED package according to claim 1, characterized in that it comprises a sealing resin body formed on the side of the first surface of the substrate so as to cover the outer circumference of the LED chip.

11. A single LED chip is mounted on the first surface of the substrate. The LED package according to claim 10, characterized in that the sealing resin body is formed to cover the outer circumference of a single LED chip.

Images