LED Package

Abstract

We provide an LED package with high light extraction efficiency, equipped with an LED chip that emits infrared light with a peak wavelength of 1,800 nm to 2,000 nm. [Solution] The LED package comprises an LED chip with an emission peak wavelength of 1,800 nm to 2,000 nm and a resin encapsulant that seals the LED chip. The resin is made of a material that exhibits an absorption spectrum having a maximum value at a first wavelength belonging to the wavelength range of 1,800 nm to 2,000 nm, and the encapsulant has a convex shape that protrudes away from the LED chip, and the full width at half maximum of infrared light that has passed through the encapsulant is narrower than the full width at half maximum of the emission spectrum of the bare LED chip.

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 1,000 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 1,000 nm or more are generally manufactured using the following procedure: A first-conductivity semiconductor layer, an active layer (sometimes called the "emission-emitting layer"), and a second-conductivity 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, it 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 1,000 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 more efficient infrared LED elements. The applicant has previously proposed technology for infrared LED elements with emission wavelengths of 1,000 nm or higher 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 Initiative] [Problems that the invention aims to solve] 【0007】 In the wavelength range of 1,000 nm or more, it is known that there is an absorption band of water (H2O). Conventionally, a moisture detection method using an infrared light source that emits infrared light in this wavelength range and a light receiving sensor has been performed by utilizing the absorption band near 1,450 nm. 【0008】 The absorption coefficient of water in the 1,900 nm band is about four times higher than that in the 1,450 nm band. Therefore, if an infrared light source in the 1,900 nm band can be used, it becomes possible to detect trace amounts of moisture, and it can also be expected to be applied to sensing. 【0009】 However, at the time of filing of the present application, LED packages equipped with LED chips having a peak emission wavelength of 1,800 nm to 2,000 nm, including 1,900 nm, have not been sufficiently developed at present. 【0010】 For example, in wavelength ranges that are extremely short compared to the above wavelength range of 1,800 nm to 2,000 nm, such as the ultraviolet range and the visible range, LED packages in which LED chips are encapsulated with resin have been put on the market from the viewpoints of improving light extraction efficiency and waterproofing and dustproofing. However, infrared light with a peak wavelength of 1,800 nm to 2,000 nm is easily absorbed by the resin material for encapsulation. Therefore, from the viewpoint of preventing a decrease in light extraction efficiency, it is conceivable to package the bare chip without resin encapsulation. 【0011】 However, in the case of the bare chip state, since the refractive index difference at the interface between the light extraction surface in the LED chip composed of a semiconductor and air is large, the ratio of total reflection is high, and sufficient light extraction efficiency cannot be obtained. That is, in an LED chip that emits infrared light with a peak wavelength of 1,800 nm to 2,000 nm, when resin encapsulation is performed to reduce the ratio of total reflection, light absorption by the resin becomes a problem, and when resin encapsulation is not performed, total reflection at the interface between the light extraction surface and air becomes a problem. 【0012】 As of the filing date of this application, there are currently no sufficient proposals for methods to improve the light extraction efficiency of LED packages equipped with LED chips that emit infrared light with a peak wavelength of 1,800 nm to 2,000 nm compared to conventional methods. In view of this problem, the present invention aims to improve the light extraction efficiency of LED packages equipped with LED chips that emit infrared light with a peak wavelength of 1,800 nm to 2,000 nm. [Means for solving the problem] 【0013】 The LED package according to the present invention is LED chips with emission peak wavelengths of 1,800nm ​​to 2,000nm, The LED chip is enclosed in a resin encapsulant, The resin is formed from a material that exhibits an absorption spectrum having a maximum value at the first wavelength within the wavelength range of 1,800 nm to 2,000 nm. The encapsulant has a convex shape that protrudes in a direction away from the LED chip, The characteristic feature is that the full width at half maximum (FMAX) of the spectrum of infrared light that has passed through the sealant is narrower than the FMAX of the emission spectrum of the bare LED chip. 【0014】 In this specification, "an absorption spectrum having a maximum value at the first wavelength within the wavelength range of 1,800 nm to 2,000 nm" means that the first wavelength exhibits the highest absorbance within the wavelength range of 1,800 nm to 2,000 nm. Hereafter, the infrared region of 1,800 nm to 2,000 nm may be referred to as the "specific infrared region" as appropriate. 【0015】 When an LED chip is sealed with a resin material that exhibits an absorption spectrum with a maximum value at the first wavelength within a specific infrared region, a portion of the infrared light emitted from the LED chip is absorbed by this resin. It is thought that the amount of infrared light absorbed increases as the optical path length of the infrared light traveling through the resin increases. Therefore, from the viewpoint of suppressing total internal reflection, it is advisable to seal the LED chip with a resin thickness that is within the minimum range necessary for sealing. 【0016】 However, through diligent research by the inventors, they obtained a surprising result: when the resin encapsulant was made convex in the direction away from the LED chip, contrary to the expectation that the absorption amount would increase due to the length of the optical path of infrared light traveling through the encapsulant, the amount of light extracted was improved compared to the bare chip case. 【0017】 Furthermore, as mentioned above, this resin exhibits an absorption spectrum in which the absorbance is highest at the first wavelength within the specific infrared region of 1,800 nm to 2,000 nm. Therefore, as infrared light travels through the encapsulant, the light intensity near this first wavelength is relatively weaker compared to the light intensity of other wavelengths belonging to the specific infrared region. As a result, the infrared light extracted from the encapsulant becomes narrowband light. 【0018】 In infrared LEDs, which emit light with extremely long wavelengths in the range of 1,800 nm to 2,000 nm compared to ultraviolet LEDs, the energy band gap (hereinafter abbreviated as Eg) of the active layer becomes extremely small. Eg is determined by the material of the active layer, but is affected by the quality of its crystallinity. Against this backdrop, the spectrum of infrared light emitted from an LED chip with a peak wavelength of 1,800 nm to 2,000 nm tends to be broadband and has an extremely wide half-width compared to ultraviolet light emitted from an ultraviolet LED chip. 【0019】 Using light with a broad half-width spectrum for substance detection can lead to false detections. When considering whether or not a target substance is present in an object, it is ideal to irradiate the object with light (hereinafter referred to as "detection light") that exhibits an emission spectrum where the light intensity in the wavelength range with a relatively high absorption coefficient in the absorption spectrum of the target substance is higher than the light intensity in other wavelength ranges. By observing the change in the intensity of the detection light before and after it is incident on the object, it is possible to determine whether or not the object contains the target substance. 【0020】 However, if the detection light exhibits a broad spectrum, it will show high light intensity in wavelength ranges where substances other than the target substance present in the object have relatively high absorption coefficients. In this case, even though the object does not contain the target substance, the intensity of the detection light after it is incident on the object will decrease compared to the intensity of the detection light before it is incident, potentially leading to a false detection that the object contains the target substance. 【0021】 However, according to the LED package of the present invention, infrared light emitted from the LED chip, which belongs to a specific infrared region with a peak wavelength of 1,800 nm to 2,000 nm, undergoes a process within the encapsulation body during which the light intensity near the first wavelength within this specific infrared region weakens relatively compared to the light intensity of other wavelengths belonging to the specific infrared region. As a result, the infrared light extracted from the LED package exhibits a spectrum within the specific infrared region where the light intensity near the first wavelength is relatively weak and the light intensities of other wavelengths are relatively high, resulting in a narrowband spectrum. This allows it to be used as a detection light source with relatively high detection accuracy. However, when this LED package is used as a detection light source, the wavelength at which the absorption coefficient of the substance to be detected is relatively high (typically the peak wavelength) must be shifted from the first wavelength, which depends on the resin material constituting the encapsulation body, within the specific infrared region of 1,800 nm to 2,000 nm. This shift is preferably 20 nm or more, more preferably 30 nm or more, and particularly preferably 50 nm or more. For the reasons described above, when using an LED package as a light source for detection, the resin material constituting the encapsulation should be appropriately selected depending on the substance to be detected. 【0022】 Silicone resin or epoxy resin can be used as the resin constituting the encapsulant. 【0023】 The aforementioned LED package is A substrate on which the aforementioned LED chip is mounted, The substrate comprises a cylindrical reflector positioned on the mounting surface side of the LED chip, so as to surround the LED chip when viewed in the direction normal to the mounting surface, The length of the reflector in the direction normal to the mounting surface is longer than the length of the LED chip in the direction normal to the mounting surface. The sealing body may be formed to fill the inside of the reflector and to protrude from the top surface of the reflector on the side furthest from the mounting surface in a direction away from the mounting surface. 【0024】 In this case, if W is the width of the encapsulant when viewed in the direction normal to the mounting surface, and H2 is the length of the reflector protruding from the top surface in the direction away from the mounting surface, then it is preferable that the value of H2 / W be within the range of 0.4 to 1.0. Satisfying this condition further improves the light output extracted from the LED package. 【0025】 The aforementioned LED chip is Support substrate and A reflective layer disposed on the upper layer of the support substrate, An insulating layer disposed on top of the reflective layer, A first electrode formed penetrating the insulating layer, with multiple electrodes dispersed in a direction along the surface of the support substrate, A semiconductor laminate is formed on the upper layer of the insulating layer, in which a first semiconductor layer of p-type or n-type, an active layer, and a second semiconductor layer of a different conductivity type than the first semiconductor layer are stacked in order from the side of the support substrate. The semiconductor laminate may also have a second electrode formed on the upper layer. [Effects of the Invention] 【0026】 According to the present invention, in an LED package equipped with an LED chip that emits infrared light with a peak wavelength of 1,800 nm to 2,000 nm, it is possible to improve the light extraction efficiency compared to a bare chip. [Brief explanation of the drawing] 【0027】 [Figure 1] This is a schematic cross-sectional view showing the structure of one embodiment of an LED package. [Figure 2] This is an example of a transmission spectrum of a silicone resin. [Figure 3] This is an example of a transmission spectrum of epoxy resin. [Figure 4] This is a schematic cross-sectional view showing an example of the structure of an LED chip. [Figure 5] This is an example of the spectrum of infrared light emitted from a bare LED chip. [Figure 6] Figure 5 shows a schematic cross-sectional view, following Figure 1, of one embodiment of an LED package for a comparative example, which is equipped with a bare LED chip whose emission spectrum was measured. [Figure 7] This is an example of the infrared light spectrum extracted from an LED package with the structure shown in Figure 1, which is equipped with an LED chip exhibiting the emission spectrum shown in Figure 5. [Figure 8] Figure 5 shows a schematic cross-sectional view of one embodiment of an LED package for comparative examples, which is equipped with the LED chip whose emission spectrum was measured, following Figure 1. [Figure 9] This is an example of the infrared light spectrum extracted from an LED package with the structure shown in Figure 8, which is equipped with an LED chip exhibiting the emission spectrum shown in Figure 5. [Figure 10] This graph compares the light intensity emitted from LED package 1 shown in Figure 1, LED package 61 shown in Figure 6, and LED package 62 shown in Figure 8. [Figure 11] This is a schematic diagram illustrating the width W and projection height H2 of the sealing body 8. [Figure 12] This graph shows the relationship between the ratio of the protrusion height H2 to the width W of the encapsulation body 8 and the infrared light output extracted from the LED package 1. [Figure 13] This graph shows the relationship between the ratio of the protrusion height H2 to the width W of the encapsulation body 8 and the full width at half maximum of the infrared light spectrum extracted from the LED package 1. [Modes for carrying out the invention] 【0028】 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. 【0029】 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. 【0030】 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. 【0031】 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". 【0032】 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 3, an LED chip 10 mounted on the substrate 3, and a resin encapsulant 8 that covers the outer periphery of the LED chip 10. 【0033】 The LED chip 10 emits infrared light L with a peak wavelength in the range of 1,800 nm to 2,000 nm. An example configuration of the LED chip 10 is described in detail with reference to Figure 4. 【0034】 In the example shown in Figure 1, a pair of lead frames 4a and 4b made of conductive material are arranged on the substrate 3. The LED chip 10 is fixed to the upper surface of lead frame 4a via a conductive bonding member 5. The LED chip 10 is also connected to lead frame 4b on the upper side via a wire 6. When a voltage is applied between lead frame 4a and lead frame 4b from a power supply (not shown), current flows within the LED chip 10, causing the LED chip 10 to emit infrared light L. 【0035】 The substrate 3 serves both the function of mounting the LED chip 10 and the function of dissipating heat from the LED chip 10. From this viewpoint, the substrate 3 is preferably made of a material with relatively high thermal conductivity and rigidity. However, since it is necessary to avoid short circuits between the lead frame 4a and the lead frame 4b, the substrate 3 is required to be made of an insulating material. From this viewpoint, aluminum nitride is typically used as the material for the substrate 3. Other examples of materials that constitute the substrate 3 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 3 may be composed of two or more of the materials listed above, or small amounts of other substances may be mixed in addition to the materials listed above (main substances). 【0036】 The conductive bonding member 5 is typically composed of solder material. Typically, Sn-Ag-Cu solder is used as such solder material. Other examples of materials that make up the bonding member 5 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 materials that make up the bonding member 5 may be 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). 【0037】 The LED package 1 shown in Figure 1 includes a reflector 7. The reflector 7 is cylindrical and is positioned on the side of the substrate 3 where the LED chip 10 is mounted (mounting surface 3a side), so as to surround the LED chip when viewed in the direction normal to the surface of the substrate 3 (mounting surface 3a). The reflector 7 is made of a material that exhibits reflectivity to infrared light L emitted from the LED chip 10, and is provided for the purpose of directing the direction of propagation of the light beam component with a large divergence angle (the light beam component that spreads in the direction along the mounting surface 3a of the substrate 3) of the infrared light L emitted from the LED chip 10 toward the outer surface 8a of the encapsulation body 8, which is the light extraction surface. Reflector 7 is composed of, for example, metal materials such as aluminum, silicone resins, epoxy resins such as glass epoxy, resin materials such as polyphthalamide, polycarbonate, polybutylene terephthalate, and polymethyl methacrylate, and ceramic materials such as aluminum nitride, aluminum oxide, zirconium oxide, silicon oxide, silicon carbide, and silicon nitride. 【0038】 The encapsulant 8 is made of resin. This resin is in the wavelength range of 1,800 nm to 2,000 nm (hereinafter referred to as "specific infrared region λ"). p This refers to a material that exhibits an absorption spectrum with a maximum value at the first wavelength within the specified range. Typical examples of such resins include silicone resins and epoxy resins. 【0039】 Figure 2 shows an example of a transmission spectrum of a silicone resin. According to Figure 2, the silicone resin exhibits a specific infrared spectrum in the 1,800 nm to 2,000 nm range. p Within this range, the transmittance at a wavelength λ1 around 1,845 nm is lower than that at other wavelengths. In other words, the transmittance in the specific infrared region λ1 from 1,800 nm to 2,000 nm is lower. p Within the material, the wavelength λ1 exhibits the highest absorbance, showing a maximum value on the absorption spectrum. In silicone resin, this wavelength λ1 corresponds to the first wavelength. 【0040】 Figure 3 shows an example of the transmission spectrum of epoxy resin. According to Figure 3, epoxy resin exhibits a specific infrared region λ from 1,800 nm to 2,000 nm.p Within this range, the transmittance at a wavelength λ2 around 1,923 nm is lower than that at other wavelengths. In other words, the transmittance in the specific infrared region λ2 from 1,800 nm to 2,000 nm is lower. p Within the material, the wavelength λ2 exhibits the highest absorbance, showing a maximum value on the absorption spectrum. In epoxy resins, this wavelength λ2 corresponds to the first wavelength. 【0041】 In the LED package 1 shown in Figure 1, the resin encapsulant 8 described above fills the inside of the reflector 7 and is formed to protrude above the reflector 7, that is, away from the mounting surface 3a of the substrate 3. 【0042】 Figure 4 is a schematic cross-sectional view showing an example of the structure of an LED chip 10. The LED chip 10 illustrated in Figure 4 includes a support substrate 11, a reflective layer 15, an insulating layer 17, a first electrode 31, a semiconductor laminate 20, and a second electrode 41. 【0043】 The semiconductor laminate 20 is a stack of multiple semiconductor layers, and includes a first semiconductor layer 23, an active layer 25, and a second semiconductor layer 27. Each semiconductor layer constituting the semiconductor laminate 20 is made of a material that can be epitaxially grown in lattice matching on an InP substrate. 【0044】 The first semiconductor layer 23 is, for example, a p-type semiconductor layer. The first semiconductor layer 23 may include a contact layer (hereinafter referred to as the "first contact layer" for convenience) located in a region close to the support substrate 11 and having a relatively high dopant concentration, and a cladding layer (hereinafter referred to as the "first cladding layer" for convenience) located in a region close to the active layer 25 and having a relatively lower dopant concentration than the first contact layer. 【0045】 In this case, the first contact layer is composed of, for example, p-type GaInAsP. The thickness of the first contact layer is not limited, but is, for example, 10 nm to 1,000 nm, preferably 50 nm to 500 nm. The p-type dopant concentration of the first contact layer is preferably 5 × 10⁻¹⁶. 17 / cm 3 ~3×1019 / cm 3 and more preferably, 1×10 18 / cm 3 ~2×10 19 / cm 3 . 【0046】 The first cladding layer included in the first semiconductor layer 23 is formed on the upper layer of the first contact layer and is made of, for example, p-type InP. The thickness of the first cladding layer is not limited, but is, for example, 1,000 nm to 10,000 nm, and preferably 2,000 nm to 5,000 nm. The p-type dopant concentration of the first cladding layer is preferably 1×10 17 / cm 3 ~3×10 18 / cm 3 at a position away from the active layer 25, and more preferably, 5×10 17 / cm 3 ~3×10 18 / cm 3 . 【0047】 As the p-type dopant included in the first semiconductor layer 23, Zn, Mg, Be, etc. can be used, Zn or Mg is preferable, and Zn is particularly preferable. 【0048】 The active layer 25 is a semiconductor layer formed on the upper layer of the first semiconductor layer 23. The material of the active layer 25 can generate infrared light L having a target wavelength, that is, infrared light L belonging to a wavelength range with a peak wavelength of 1,800 nm to 2,000 nm, and is appropriately selected from materials that can be epitaxially grown in lattice matching with the InP substrate. As an example, the active layer 25 may have a single-layer structure of InGaAs, or may have a MQW (Multiple Quantum Well) structure including a well layer made of InGaAs and a barrier layer made of GaInAsP, AlGaInAs, InGaAs, or InP having a larger bandgap energy than the well layer. [[ID=​40]] 【0049】 The thickness of the active layer 25 is 50 nm to 2,000 nm, preferably 100 nm to 1,000 nm, when the active layer 25 has a single-layer structure. When the active layer 25 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. The active layer 25 may be doped with n-type or p-type, or it may be undoped. When doped with n-type, for example, Si can be used as the dopant. 【0050】 The second semiconductor layer 27 is located on top of the active layer 25. The second semiconductor layer 27 may include a cladding layer located in a region close to the active layer 25 with a relatively low dopant concentration (hereinafter referred to as the "second cladding layer" for convenience) and a contact layer located in a region farther from the active layer 25 with a relatively higher dopant concentration than the second cladding layer (hereinafter referred to as the "second contact layer" for convenience). 【0051】 The second cladding layer included in the second semiconductor layer 27 is, for example, n-type InP. The thickness of the second cladding layer is not limited, but is, for example, 100 nm to 10,000 nm, and preferably 500 nm to 5,000 nm. The n-type dopant concentration of the second cladding layer is preferably 1 × 10⁻⁶. 17 / cm 3 ~5×10 18 / cm 3 And more preferably, 5 × 10 17 / cm 3 ~4×10 18 / cm 3 The n-type impurity material used to dope the second cladding layer can be Sn, Si, S, Ge, Se, etc., with Si being particularly preferred. 【0052】 The second contact layer included in the second semiconductor layer 27 is, for example, n-type InP. The thickness of the second contact layer is not limited, but is, for example, 10 nm to 1,000 nm, and preferably 50 nm to 500 nm. The n-type dopant concentration of the second contact layer is preferably 5 × 10⁻¹⁶. 17 / cm 3 ~1 × 10 19 / cm 3 And moreover, 1 × 10 18 / cm 3 ~5×10 18 / cm 3 That is the case. 【0053】 As shown in Figure 4, the semiconductor laminate 20 described above is formed on one main surface of the support substrate 11. The encapsulant 8, which was described with reference to Figure 1, is placed on the second semiconductor layer 27 side of the semiconductor laminate 20. In other words, in the LED chip 10, the second semiconductor layer 27 side corresponds to the light extraction surface. 【0054】 The support substrate 11 is made of a semiconductor such as Si or Ge, or a metallic material such as Cu or CuW. If the support substrate 11 is made of a semiconductor, it may be doped with a high concentration of dopants to exhibit conductivity. As an example, the support substrate 11 may be doped with 1 × 10⁻¹⁶ boron (B). 19 / cm 3 The Si substrate is doped with the above dopant concentrations and has a resistivity of 10 mΩcm or less. In addition to boron (B), other dopants such as phosphorus (P), arsenic (As), and antimony (Sb) can be used. From the viewpoint of achieving both high heat dissipation and low manufacturing costs, a Si substrate is preferably used as the support substrate 11. The thickness of the support substrate 11 is not particularly limited, but is for example 50 μm to 500 μm, and preferably 100 μm to 300 μm. 【0055】 The LED chip 10 has a conductive layer 16 formed on the upper layer of the support substrate 11. More specifically, the conductive layer 16 includes a bonding layer 13 and a reflective layer 15. 【0056】 The bonding layer 13 is made of a low-melting-point solder material and is composed of, for example, Au, Au-Zn, Au-Sn, Au-In, Au-Cu-Sn, Cu-Sn, Pd-Sn, Sn, etc. This bonding layer 13 is used to bond the InP substrate, on which the semiconductor laminate 20 has grown on its upper surface, to the support substrate 11. The LED chip 10 shown in Figure 4 is manufactured by bonding the InP substrate to the support substrate 11 and then removing the InP substrate. The thickness of the bonding layer 13 is not particularly limited, but is, for example, 0.5 μm to 5.0 μm, and preferably 1.0 μm to 3.0 μm. 【0057】 The reflective layer 15 functions to reflect infrared light L2, which is generated in the active layer 25 and propagates toward the support substrate 11, and guide it toward the light extraction surface (second semiconductor layer 27). The reflective layer 15 is made of a conductive material that exhibits high reflectivity to infrared light L. The reflectivity of the reflective layer 15 toward infrared light L is preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more. The peak wavelength is in the specific infrared region λ of 1,800 nm to 2,000 nm. p From the viewpoint of effectively reflecting infrared light L belonging to the interior, it is preferable to use a metallic material such as Ag, Ag alloy, Au, Al, or Cu for the reflective layer 15. The thickness of the reflective layer 15 is not particularly limited, but is, for example, 0.1 μm to 2.0 μm, and preferably 0.3 μm to 1.0 μm. 【0058】 Although not shown in Figure 4, the conductive layer 16 may further include a barrier layer between the reflective layer 15 and the bonding layer 13 to suppress the diffusion of the solder material constituting the bonding layer 13. The barrier layer can be made of a material containing Ti, Pt, W, Mo, Ni, etc. As an example, it is made of a Ti / Pt / Au laminate. The thickness of the barrier layer is not particularly limited, but is, for example, 0.05 μm to 3 μm, preferably 0.2 μm to 1 μm. The presence of this barrier layer prevents the material of the bonding layer 13 from diffusing towards the reflective layer 15 and reducing the reflectivity of the reflective layer 15. The barrier layer may also be provided between the bonding layer 13 and the support substrate 11. 【0059】 The LED chip 10 includes an insulating layer 17 formed on top of the reflective layer 15. The insulating layer 17 is made of a material that exhibits electrical insulation and has high transmittance to infrared light L. 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. The insulating layer 17 can be made of materials such as SiO2, SiN, Al2O3, or AlN. 【0060】 The LED chip 10 includes first electrodes 31 that penetrate the insulating layer 17 at multiple locations within the insulating layer 17. In this embodiment, the first electrodes 31 are arranged in multiple dispersed directions parallel to the main surface of the support substrate 11, and electrically connect the reflective layer 15 and the first semiconductor layer 23 at multiple locations. The first electrodes 31 are made of a material capable of forming ohmic connections with the first semiconductor layer 23 (more specifically, the first contact layer), and are, for example, made of AuZn, AuBe, or a laminated structure containing at least Au and Zn (e.g., Au / Zn / Au). 【0061】 The first electrode 31 is provided for the purpose of uniformly distributing current over a wide area within the active layer 25 in a direction parallel to the main surface of the support substrate 11. From this viewpoint, it is preferable that the first electrode 31 is arranged in a dispersed state with a regular shape in the direction along the main surface of the support substrate 11. However, in the present invention, the shape of the arrangement pattern of the first electrode 31 when viewed in the direction normal to the main surface of the support substrate 11 is arbitrary. 【0062】 The LED chip 10 has a second electrode 41 positioned in contact with the upper surface of the second semiconductor layer 27. For example, the second electrode 41 may be configured such that multiple electrodes extend in a direction parallel to the edge of the semiconductor laminate 20. This allows for uniform current flow over a wide area within the active layer 25 in a direction parallel to the main surface of the support substrate 11. However, in this invention, the pattern shape of the second electrode 41 is arbitrary. For example, the second electrode 41 may be composed of a material such as AuGe / Ni / Au or Au / Ge / Au, and may also consist of multiple materials. 【0063】 The LED chip 10 has a pad electrode 42 positioned in contact with the upper surface of the second electrode 41. The pad electrode 42 is provided to secure a region for contact with the power supply wire 6 (see Figure 1). The pad electrode 42 is made of, for example, Ti / Au, Ti / Pt / Au, etc. In the example shown in Figure 1, the pad electrode 42 and the lead frame 4b are electrically connected via the wire 6. 【0064】 The LED chip 10 includes a back electrode 33 formed on the side of the support substrate 11 opposite to the semiconductor laminate 20. The back electrode 33 achieves ohmic contact with the support substrate 11. The back electrode 33 is composed of materials such as Ti / Au, Ti / Pt / Au, for example, and may consist of multiple such materials. In the example shown in Figure 1, the back electrode 33 and the lead frame 4a are electrically connected via a conductive bonding member 5. 【0065】 The LED chip 10 includes a protective layer 37 that is positioned to cover the sides and top surface of the semiconductor laminate 20. The protective layer 37 is provided to prevent foreign matter from adhering to the semiconductor laminate 20 and moisture from flowing in. When the protective layer 37 is positioned to cover the top surface of the semiconductor laminate 20, the protective layer 37 is made of a material that exhibits electrical insulation properties and has high transmittance to infrared light L, similar to the insulating layer 17. The transmittance of the protective layer 37 to infrared light L is preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more. The protective layer 37 can be made of materials such as SiO2, SiN, Al2O3, and AlN. From the viewpoint of reducing the proportion of total internal reflection of infrared light L on the surface of the protective layer 37, it is preferable to make the top surface 50 of the protective layer 37 uneven, as shown in Figure 4. 【0066】 Figure 5 shows an example of the spectrum of infrared light L emitted from a bare LED chip 10. More specifically, as shown in Figure 6, the spectrum of infrared light L emitted from an LED package 61, in which the bare LED chip 10 is mounted on a substrate 3, was measured. According to Figure 5, the emission peak wavelength is approximately 1,895 nm, which corresponds to the specific infrared region λ of 1,800 nm to 2,000 nm mentioned above. p It belongs to [a specific group / category]. The half-width of this emission spectrum was 230 nm. 【0067】 Figure 7 shows an example of the spectrum of infrared light L extracted from the LED package 1 shown in Figure 1, which is equipped with an LED chip 10 that emits infrared light L as shown in Figure 5. In this example, silicone resin was used as the material for the encapsulant 8. 【0068】 According to the spectrum shown in Figure 7, the peak wavelength is approximately 1,895 nm, the same as in Figure 5, but the specific infrared region λ from 1,800 nm to 2,000 nm is also present. p wavelength λ belonging to this group a A drop in light intensity is observed in the vicinity of [the specified point]. Furthermore, the full width at half maximum of the spectrum shown in Figure 7 is 140 nm, which represents a narrower bandwidth than the spectrum shown in Figure 5. 【0069】 Wavelength λ in Figure 7 a This is around 1,845 nm, which is approximately the same as the wavelength λ1 mentioned above, as shown in Figure 2. In other words, it is thought that as the infrared light L emitted from the LED chip 10 travels through the silicone resin encapsulant 8, some of the infrared light L is absorbed by the silicone resin constituting the encapsulant 8 and then extracted to the outside. 【0070】 In detail, the LED chip 10 emitted light in a specific infrared region λ with a peak wavelength of 1,800 nm to 2,000 nm. p Infrared light L belonging to the λ region travels through the silicone resin seal 8, and in the process, it travels through a specific infrared region λ. p Within the region, near wavelength λ1, where the absorption coefficient is relatively higher than the transmittance of the surrounding wavelengths (wavelength λ in Figure 7) aIt is thought that wavelength components in the vicinity were absorbed. As a result, the infrared light L extracted from LED package 1 has been narrowed in bandwidth. 【0071】 Furthermore, from this perspective, the peak wavelength of the infrared light L emitted from the LED chip 10 and the specific infrared region λ of the resin constituting the encapsulant 8 are considered. p It is preferable that the wavelength with the highest absorption coefficient within the wavelength range be offset from the wavelength with the highest absorption coefficient. This offset is preferably 20 nm or more, more preferably 30 nm or more, and particularly preferably 50 nm or more. 【0072】 Figure 8 is a schematic cross-sectional view, following Figure 1, showing the structure of an LED package 62 as a comparative example, which is equipped with an LED chip 10 that emits infrared light L as shown in Figure 5. 【0073】 The comparative example LED package 62 shown in Figure 8, like the LED package 1 shown in Figure 1, includes a encapsulant 68 that encloses the LED chip 10. However, the outer surface 68a of this encapsulant 68 is located closer to the base 3 than the top surface 7a of the reflector 7, and the outer surface 68a is composed of a nearly flat surface. In contrast, the outer surface 8a of the encapsulant 8 of the LED package 1 shown in Figure 1 protrudes away from the base 3 than the top surface 7a of the reflector 7, resulting in a convex shape that protrudes away from the LED chip 10. 【0074】 Figure 9 shows an example of the infrared light L spectrum extracted from an LED package 62 having the structure shown in Figure 8, which is equipped with an LED chip 10 that emits infrared light L as shown in Figure 5. The encapsulant 68 of the LED package 62 was made of silicone resin, just like the encapsulant 8 of the LED package 1 shown in Figure 1, from which the spectrum shown in Figure 7 was measured. 【0075】 According to the spectrum shown in Figure 9, the peak wavelength is approximately 1,895 nm, the same as in Figure 5, but the specific infrared region λ from 1,800 nm to 2,000 nm is also present. p wavelength λ belonging to this groupa A drop in light intensity is observed in the vicinity of [the specified point]. The full width at half maximum of the spectrum is 170 nm, which is narrower than the spectrum in Figure 5. 【0076】 However, the spectrum shown in Figure 9 is wider than the full width at half maximum of the spectrum shown in Figure 7. This is presumed to be because the thickness of the encapsulant 68 in the LED package 62 shown in Figure 8 is thinner than that of the encapsulant 8 in the LED package 1 shown in Figure 1. In other words, the optical path length of the infrared light L emitted from the LED chip 10 in the LED package 62 shown in Figure 8, as it travels through the silicone resin encapsulant 68, is shorter than the optical path length of the infrared light L emitted from the LED chip 10 in the LED package 1 shown in Figure 1, as it travels through the silicone resin encapsulant 8. As a result, the amount of infrared light L absorbed within the encapsulant 68 is less than the amount of light absorbed within the encapsulant 8. 【0077】 Figure 10 is a graph comparing the light intensity emitted from LED package 1 shown in Figure 1, LED package 61 shown in Figure 6, and LED package 62 shown in Figure 8. In Figure 10, the horizontal axis represents the input current to the LED chip 10, and the vertical axis represents the light output. 【0078】 Based on the above considerations, it is expected that in LED package 1 equipped with a encapsulant 8 and LED package 62 equipped with a encapsulant 68, the light output will be lower compared to LED package 61 equipped with a bare chip, as infrared light L is absorbed by the encapsulant 8 and 68. The fact that the light output of infrared light L extracted from LED package 62 is lower than the light output of infrared light L extracted from LED package 61 is consistent with this expectation. 【0079】 However, as shown in Figure 10, the infrared light L output from LED package 1 equipped with the encapsulant 8 exceeds not only the infrared light L output from LED package 62 equipped with a thinner encapsulant 68 than encapsulant 8, but also the infrared light L output from LED package 61 equipped with a bare chip without encapsulant 8. This result is unexpected and surprising. 【0080】 As described above with reference to Figure 2, the silicone resin has a specific infrared region λ of 1,800 nm to 2,000 nm. p The absorption coefficient is high at the first wavelength λ1, which belongs to this region. Therefore, the peak wavelength is in this specific infrared region λ. p It was previously thought that when infrared light L, such as that belonging to the genotype, travels through a silicone resin encapsulant 8, the longer the optical path length, the greater the absorption of infrared light L and the lower the light output. However, in reality, a higher light output was obtained than that obtained from an LED package 61 without an encapsulant 8. The inventors speculated that this was because, as shown in Figure 1, the shape of the encapsulant 8 was made convex, protruding in the direction away from the LED chip 10. Although this increased the thickness of the encapsulant 8 and lengthened the optical path length of the infrared light L traveling through it, contrary to expectations, the amount of infrared light L extracted through the encapsulant 8 exceeded the amount of light absorbed within the encapsulant 8. 【0081】 In particular, as shown in Figure 4, when the LED chip 10 is configured to include a support substrate 11, an InP substrate is used as the growth substrate to epitaxially grow a semiconductor laminate 20, an insulating layer 17 and a reflective layer 15 are formed on the upper surface of the semiconductor laminate 20, and then the support substrate 11 is bonded to it via a bonding layer 13. After that, the growth substrate is removed. In the case of an LED chip 10 with such a structure, the thickness of the light-emitting region can be made thinner compared to an LED chip in which the InP substrate as the growth substrate remains intact. This is because, in the case of an LED chip in which the InP substrate remains intact, light is extracted from the InP substrate itself, whereas in the case of the LED chip 10 shown in Figure 4, light is not extracted through the support substrate 11, but rather from the semiconductor laminate 20 side, which is extremely thin compared to the support substrate 11. In other words, an LED chip in which the InP substrate remains intact is a relatively "volume-emitting" chip, while the so-called "bonded" LED chip 10 shown in Figure 4 is a relatively "surface-emitting" chip. 【0082】 The smaller the surface area of ​​the region that emits light as an LED chip, the greater the effect of increasing the amount of infrared light L extracted by providing a convex-shaped encapsulant 8. In other words, the effect of increasing the amount of infrared light L by providing a convex-shaped encapsulant 8 is more pronounced in a surface-emitting LED chip 10 as shown in Figure 4 than in a volume-emitting LED chip where the InP substrate remains as is. 【0083】 Based on the above inferences, the inventors conducted further studies on the shape of the encapsulant 8 that could further improve the light extraction efficiency. Specifically, as shown in Figure 11, the width of the encapsulant 8 at the height position of the top surface 7a of the reflector 7 was defined as W, and the protrusion height of the encapsulant 8 that protrudes in the direction away from the LED chip 10 from the top surface 7a of the reflector 7 was defined as H2. LED packages 1 equipped with multiple shapes of encapsulant 8 with different ratios of width W to protrusion height H2 were manufactured and emitted light. The results are shown in Figures 12 and 13. 【0084】 Figure 12 is a graph in which the horizontal axis represents the ratio of the projection height H2 to the width W, and the vertical axis represents the optical output. Figure 13 is a graph in which the horizontal axis represents the ratio of the projection height H2 to the width W, and the vertical axis represents the full width at half maximum of the spectrum. In Figure 12, the optical output is represented by the integrated intensity obtained by receiving the infrared light L emitted from each LED package 1 using an integrating sphere. 【0085】 In Figures 12 and 13, the results when the ratio of the protruding height H2 to the width W is 0 correspond to the LED package 62 with a encapsulant 68 whose outer surface 68a is a nearly flat surface, as shown in Figure 8. Also, for comparison, in Figures 12 and 13, the results for an LED package 61 with a bare chip mounted without a encapsulant (8,68) are shown by a dashed line. 【0086】 As shown in Figure 12, it was confirmed that the light output improves compared to the LED package 61 with a bare chip when the ratio of the protruding height H2 to the width W (H2 / W) exceeds approximately 0.3. It can be seen that if the ratio H2 / W is in the range of 0.4 to 1.0, a significantly higher light output than the LED package 61 can be obtained. Although verification has not been performed when the ratio H2 / W exceeds 1.0, based on the results in Figure 12, it is expected that the light output will increase even further. 【0087】 As shown in Figure 13, within the range of H2 / W ratio from 0.4 to 1.0, the higher the H2 / W ratio, the narrower the full width at half maximum (FWHM) of the infrared light L extracted from the LED package 1 becomes. Although verification for H2 / W ratios exceeding 1.0 has not been performed, based on the results in Figure 13, it is expected that the FWHM will become even narrower. 【0088】 The above verification was performed for the case where the sealant 8 is made of silicone resin. However, in light of the above considerations, if the sealant 8 is in the wavelength range of 1,800 nm to 2,000 nm (specific infrared region λ) p In the first wavelength belonging to this specific infrared region λ pAs long as the material exhibits an absorption spectrum in which it absorbs more light at wavelengths within the spectrum than other wavelengths, similar results can be expected even if it is composed of other materials such as epoxy resin. 【0089】 [Alternative Embodiment] The following describes other embodiments. 【0090】 <1> In the above embodiment, as shown in Figure 1, the LED package 1 was described as having a reflector 7, but the present invention also applies to LED packages 1 that do not have a reflector 7. Even if the LED package 1 does not have a reflector 7, the encapsulant 8 may have a shape that encapsulates the outer circumference of the LED chip 10 and protrudes in a direction away from the LED chip 10. 【0091】 However, from the viewpoint of increasing the light output extracted from the LED package 1, it is preferable that the LED package 1 is equipped with a reflector 7. 【0092】 <2> The structure of the LED chip 10 contained in the LED package 1 is not limited to that shown in Figure 4. Figure 4 is merely an example of a typical structure of the LED chip 10. 【0093】 <3> The LED package 1 can typically be used as a detection light source for detecting a predetermined target substance. However, the use of the LED package 1 is not limited in the present invention. 【0094】 (4) 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] 【0095】 1: LED package 3: Base 3a: Substrate mounting surface 4a: Lead frame 4b: Lead frame 5: Joining member 6: Wire 7: Reflector 7a: Top surface of the reflector 8: Encapsulation body 8a: Outer surface of the sealant 10: LED chip 11: Support board 13: Bonding layer 15: Reflective layer 16: Conductive layer 17: Insulating layer 20: Semiconductor laminate 23: First semiconductor layer 25:Active layer 27: Second semiconductor layer 31:First electrode 33: Backside electrode 37 :Protective layer 41:Second electrode 42: Pad electrode 61: Comparative example LED package 62: Comparative example LED package 68: Sealing body 68a: Outer surface of the sealant λ p :Specific infrared range

Claims

[Claim 1] LED chips with emission peak wavelengths of 1,800 nm to 2,000 nm, The LED chip is enclosed in a resin encapsulant, The resin is formed from a material that exhibits an absorption spectrum having a maximum value at a first wavelength within the wavelength range of 1,800 nm to 2,000 nm. The encapsulant has a convex shape that protrudes in a direction away from the LED chip, An LED package characterized in that the full width at half maximum (FMAX) of the spectrum of infrared light that has passed through the encapsulant is narrower than the FMAX of the emission spectrum of the bare LED chip. [Claim 2] The LED package according to claim 1, characterized in that the resin is a silicone resin or an epoxy resin. [Claim 3] A substrate on which the aforementioned LED chip is mounted, The substrate comprises a cylindrical reflector positioned on the mounting surface side of the LED chip, so as to surround the LED chip when viewed in the direction normal to the mounting surface, The length of the reflector in the direction normal to the mounting surface is longer than the length of the LED chip in the direction normal to the mounting surface. The LED package according to claim 1 or 2, characterized in that the encapsulant fills the inside of the reflector and is formed to protrude from the top surface of the reflector on the side furthest from the mounting surface in a direction away from the mounting surface. [Claim 4] The LED package according to claim 3, characterized in that, when the width of the encapsulant is viewed in the direction normal to the mounting surface, W is the length of the reflector protruding from the top surface in a direction away from the mounting surface, and H2 is the length of the reflector protruding in a direction away from the mounting surface, the value of H2 / W is in the range of 0.4 to 1.

0. [Claim 5] The aforementioned LED chip is Support substrate and A reflective layer disposed on the upper layer of the support substrate, An insulating layer disposed on top of the reflective layer, A first electrode formed penetrating the insulating layer, with multiple electrodes dispersed in a direction along the surface of the support substrate, A semiconductor laminate is formed on the upper layer of the insulating layer, in which a first semiconductor layer of p-type or n-type, an active layer, and a second semiconductor layer of a different conductivity type than the first semiconductor layer are stacked in order from the side of the support substrate. The LED package according to claim 1 or 2, characterized by having a second electrode formed on the upper layer of the semiconductor laminate.

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