Near-infrared light-emitting diode and method for manufacturing the same

Abstract

This invention provides a near-infrared light-emitting diode and a method for manufacturing the same. [Solution] The near-infrared light-emitting diode includes a substrate, an epitaxial composite layer, an upper electrode, and a black photoresist. The epitaxial composite layer is placed on the substrate and has an emission layer with an emission wavelength of 750 nanometers (nm) to 1000 nanometers (nm). The upper electrode is placed on the upper surface of the epitaxial composite layer. The black photoresist covers the epitaxial composite layer, exposing only the upper electrode, absorbing visible light wavelengths, and allowing only infrared light to pass through the black photoresist and be emitted to the outside.

Description

Technical Field

[0001] The present invention relates to a near-infrared light-emitting diode and a method for manufacturing the same, and particularly to a near-infrared light-emitting diode that suppresses the phenomenon of red light leakage and a method for manufacturing the same.

Background Art

[0002] The application range of near-infrared (NIR) light-emitting diodes (LEDs) covers a wide variety, including communication, medical, industrial, and consumer electronics, and continues to expand. For example, in the field of optical communication, near-infrared light-emitting diodes provide stable low-power light sources with wavelength ranges of 850 nanometers (nm) and 940 nanometers (nm). This type of light source is used for high-frequency modulation signals and short-distance data transmission, such as fiber-optic communication and high-speed local area networks. In medical applications, the light of near-infrared light-emitting diodes has the property of passing through the skin and is used for measuring oxygen saturation and heart rate in the blood. Near-infrared light-emitting diodes are applied to wearable devices to provide blood oxygen and heart rate monitoring functions.

[0003] However, the main wavelengths of general near-infrared light are 850 nanometers (nm) and 940 nanometers (nm). The emission spectra of these wavelengths are very close to or partially included in the visible light range with wavelengths of 700 nanometers (nm) or shorter. When the encapsulation of the module is defective, the "red light leakage phenomenon" is likely to occur, and red light can be seen in the dark. Currently, commercially available near-infrared light-emitting diode modules usually use encapsulating resin or an encapsulating module to block light in order to avoid the red light leakage phenomenon of visible light. This light-blocking method can block visible light, but at the same time, it also blocks near-infrared light, significantly reducing the brightness of the near-infrared light-emitting diode. The external encapsulating resin of the near-infrared light-emitting diode is easily affected by the environment, which causes the light leakage phenomenon and reduces the product reliability of the module. To solve the above problems, the industry is urgently in need of an innovative near-infrared light-emitting diode structure that improves the red light leakage phenomenon and solves the problem of light leakage caused by defective encapsulation.

Summary of the Invention

[0004] The main objective of the present invention is to provide an innovative near-infrared light-emitting diode and a method for manufacturing the same. Unlike conventional photoelectric elements, the near-infrared light-emitting diode of the present invention has an epitaxial layer covered with black photoresist. The black photoresist has the property of effectively absorbing visible light wavelengths while allowing the transmission of near-infrared light. This suppresses the red light leakage phenomenon and achieves the effect of maintaining high brightness.

[0005] To achieve the above objective, the present invention provides a near-infrared light-emitting diode comprising a substrate, an epitaxial composite layer, a top electrode, and a black photoresist. The epitaxial composite layer is placed on the substrate and has a light-emitting layer with an emission wavelength of 750 nanometers (nm) to 1000 nanometers (nm). The top electrode is placed on the upper surface of the epitaxial composite layer. The black photoresist covers the epitaxial composite layer, exposing only the top electrode, absorbing visible light wavelengths, and allowing only infrared light to pass through the black photoresist and be emitted to the outside.

[0006] In the near-infrared light-emitting diode of the present invention, the wavelength of infrared light transmitted through the black photoresist and emitted to the outside is between 850 nanometers (nm) and 940 nanometers (nm).

[0007] In the near-infrared light-emitting diode of the present invention, the thickness of the black photoresist is approximately 1 to 5 micrometers (μm).

[0008] In the near-infrared light-emitting diode of the present invention, the material of the black photoresist includes 1-methoxy-2-propanol acetate and cyclohexanone.

[0009] In the near-infrared light-emitting diode of the present invention, the epitaxial composite layer further includes a P-type epitaxial layer and an N-type epitaxial layer sandwiching the light-emitting layer.

[0010] In the near-infrared light-emitting diode of the embodiment of the present invention, the materials for the P-type epitaxial layer and the N-type epitaxial layer include gallium arsenide (GaAs) or aluminum gallium arsenide (AlGaAs), and the material for the light-emitting layer includes indium gallium arsenide (InGaAs) or aluminum gallium arsenide (AlGaAs).

[0011] In the near-infrared light-emitting diode of the embodiment of the present invention, the substrate is a gallium arsenide (GaAs) substrate or a silicon (Si) substrate.

[0012] To achieve the above objective, the present invention provides a method for manufacturing a near-infrared light-emitting diode, comprising the steps of: forming an epitaxial composite layer having an emission layer with an emission wavelength of 750 nanometers (nm) to 1000 nanometers (nm) on a substrate; installing an upper electrode on the upper surface of the epitaxial composite layer; and installing a black photoresist that covers the epitaxial composite layer and exposes only the upper electrode. The black photoresist absorbs visible light wavelengths and allows only infrared light to pass through the black photoresist and be emitted to the outside.

[0013] In the method for manufacturing a near-infrared light-emitting diode according to an embodiment of the present invention, the step of setting the black photoresist involves setting a black photoresist with a thickness of approximately 1 to 5 micrometers (μm), and the material of the black photoresist includes 1-methoxy-2-propanol acetate and cyclohexanone.

[0014] In the method for manufacturing a near-infrared light-emitting diode according to an embodiment of the present invention, the step of forming the epitaxial composite layer is to form a P-type epitaxial layer and an N-type epitaxial layer sandwiching the light-emitting layer.

[0015] In the method for manufacturing a near-infrared light-emitting diode according to an embodiment of the present invention, the materials for the P-type epitaxial layer and the N-type epitaxial layer include gallium arsenide (GaAs) or aluminum gallium arsenide (AlGaAs), and the material for the light-emitting layer includes indium gallium arsenide (InGaAs) or aluminum gallium arsenide (AlGaAs).

[0016] In the method for manufacturing a near-infrared light-emitting diode according to the embodiment of the present invention, the substrate is a gallium arsenide (GaAs) substrate or a silicon (Si) substrate.

[0017] Those skilled in the art will be able to understand other objects of the present invention, as well as the technical means and embodiments of the present invention, by referring to the drawings and the embodiments described later. [Brief explanation of the drawing]

[0018] [Figure 1] Schematic diagram of the manufacturing process of a near-infrared light-emitting diode in an embodiment of the present invention. [Figure 2] Schematic diagram of the manufacturing process of a near-infrared light-emitting diode in an embodiment of the present invention. [Figure 3] Plan diagram of a near-infrared light-emitting diode in an embodiment of the present invention [Figure 4] Schematic cross-sectional view of line segment AA in Figure 3. [Figure 5] Flowchart of the manufacturing process for near-infrared light-emitting diodes in embodiments of the present invention [Modes for carrying out the invention]

[0019] The present invention will be described below through examples. These examples illustrate the embodiments of the present invention and are not intended to limit the invention to any particular environment, application, or specific configuration described therein. Therefore, while the examples illustrate the present invention, they do not limit it. Components not directly related to the present invention are omitted and not shown in the embodiments and drawings. The dimensional relationships of the components in the drawings are for ease of understanding and do not limit the actual dimensions.

[0020] Figure 1 is a schematic diagram of the manufacturing process of a near-infrared light-emitting diode 1 in an embodiment of the present invention. In this embodiment, first a substrate 10 is prepared. The substrate 10 is preferably an opaque substrate, such as a gallium arsenide (GaAs) substrate or a silicon (Si) substrate. Next, an epitaxial composite layer 100 is formed on the substrate 10. This epitaxial composite layer 100 includes an N-type epitaxial layer 110, a light-emitting layer 120, and a P-type epitaxial layer 130. Specifically, the light-emitting layer 120 is a multiple quantum well (MQW) structure formed from an indium gallium arsenide (InGaAs) or aluminum gallium arsenide (AlGaAs) ternary compound semiconductor, and is sandwiched between the N-type epitaxial layer 110 and the P-type epitaxial layer 130. In this embodiment, the emission wavelength of the multiple quantum wells is from 750 nanometers (nm) to 1000 nanometers (nm), mainly generating near-infrared light of 850 nanometers (nm) or 940 nanometers (nm).

[0021] Furthermore, the N-type epitaxial layer 110 is an N-type gallium arsenide (GaAs) layer or an N-type aluminum gallium arsenide (AlGaAs) layer. The P-type epitaxial layer 130 is a P-type gallium arsenide (GaAs) layer or a P-type aluminum gallium arsenide (AlGaAs) layer. Note that the materials described in the above embodiments are merely examples, and the present invention is not limited thereto. In actual applications, the materials and their composition can be adjusted according to the emission wavelength. The epitaxial layer may be gallium phosphide (GaP), indium phosphide (InP), or indium gallium arsenide (InGaAs). Next, an electrode metallization process is performed to form an upper electrode 140 above the epitaxial composite layer 100 and a lower electrode 150 on the back side of the substrate 10. The materials for the upper electrode 140 and the lower electrode 150 are, for example, germanium gold (GeAu), germanium gold nickel (GeAuNi), or germanium titanium platinum gold (GeTiPtAu).

[0022] As shown in Figure 2, next, a protective layer (not shown) is formed on the element surface, and then a mesa etching (MESA) process is performed to etch a portion of the epitaxial composite layer 100. That is, a portion of the N-type epitaxial layer 110, the light-emitting layer 120, and the P-type epitaxial layer 130 is etched to form a mesa structure of the epitaxial composite layer on the substrate 10. This will be explained with reference to Figures 3 and 4. Figure 3 is a schematic plan view of a near-infrared light-emitting diode 1 in an embodiment of the present invention. Figure 4 is a schematic cross-sectional view of line AA in Figure 3. As shown in Figures 3 and 4, a coating process of black photoresist 160 is performed to completely cover the epitaxial composite layer 100, exposing only the upper electrode 140 and facilitating subsequent electrode wire bonding. In a specific embodiment, the material of the black photoresist 160 includes 1-methoxy-2-propanol acetate and cyclohexanone. The black photoresist 160 absorbs visible light wavelengths from the light-emitting layer 120, allowing only infrared light to pass through the black photoresist and be emitted to the outside. Furthermore, the black photoresist 160 absorbs red light with a wavelength of 700 nanometers (nm) and transmits only infrared light with wavelengths of 850 nanometers (nm) or 940 nanometers (nm). Therefore, the near-infrared light-emitting diode 1 of the present invention can suppress the red light leakage phenomenon of conventional near-infrared light-emitting diodes. The thickness of the black photoresist 160 is approximately 1 to 5 micrometers (μm). Preferably, the thickness of the black photoresist 160 is 3 micrometers (μm).

[0023] Note that the black photoresist that covers the epitaxial composite layer of the near-infrared light-emitting diode of the present invention is formed at the wafer stage. One wafer contains 30,000 to 40,000 near-infrared light-emitting diode chips, and the coating process of the black photoresist can be performed at one time. The black photoresist completely covers the epitaxial layer of each chip, absorbs light with visible light wavelengths, and allows only near-infrared light to be emitted to the outside. In contrast, in the prior art, a black sealing resin was used in the chip packaging stage to perform a module light-shielding process. In that conventional light-shielding process, resin treatment could be performed on only one package at a time, and a large number of packages could not be processed simultaneously. Therefore, the innovative structure and manufacturing method disclosed by the present invention achieve the effect of completely suppressing the leakage of red light by hermetic packaging, and its production process and production efficiency are superior to the conventional black resin sealing process.

[0024] Figure 5 is a flowchart of the manufacturing process of the near-infrared light-emitting diode of the present invention. First, in step S01, an epitaxial composite layer is formed on a substrate. The epitaxial composite layer has a light-emitting layer with an emission wavelength of 750 nanometers (nm) to 1000 nanometers (nm). Next, in step S02, an upper electrode is installed on the upper surface of the epitaxial composite layer. Finally, in step S03, a black photoresist that covers the epitaxial composite layer and exposes only the upper electrode is installed. The black photoresist absorbs light with visible light wavelengths and allows only infrared light to pass through the black photoresist and be emitted to the outside. The technical content of the other elements is as described above, and will not be repeated here.

[0025] The above embodiments illustrate the embodiments of the present invention and explain the characteristic configurations of the present invention. The present invention is not limited to the above embodiments. Modifications or equivalent arrangements that can be easily made by those skilled in the art are also within the scope of the present invention. The scope of protection of the rights of the present invention shall be based on the scope of the claims.

Description of Reference Numerals

[0026] 1 Near-infrared light-emitting diode 10 circuit boards 100 Epitaxial Composite Layer 110 N-type epitaxial layer 120 Emitting layer 130 P-type epitaxial layer 140 Upper electrode 150 Lower electrode 160 Black Photoresist AA line segment

Claims

1. A near-infrared light-emitting diode, circuit board and An epitaxial composite layer is provided on the substrate and has an emissive layer with an emission wavelength of 750 nanometers (nm) to 1000 nanometers (nm), An upper electrode is placed on the upper surface of the epitaxial composite layer, A near-infrared light-emitting diode comprising a black photoresist that covers the epitaxial composite layer, exposing only the upper electrode, and which absorbs visible light wavelengths and allows only infrared light to pass through and be emitted to the outside.

2. The near-infrared light-emitting diode according to claim 1, characterized in that the wavelength of infrared light transmitted through the black photoresist and emitted to the outside is between 850 nanometers (nm) and 940 nanometers (nm).

3. The near-infrared light-emitting diode according to claim 1, characterized in that the thickness of the black photoresist is approximately 1 to 5 micrometers (μm).

4. The near-infrared light-emitting diode according to claim 1, characterized in that the material of the black photoresist comprises 1-methoxy-2-propanol acetate and cyclohexanone.

5. The near-infrared light-emitting diode according to claim 1, characterized in that the epitaxial composite layer further includes a P-type epitaxial layer and an N-type epitaxial layer sandwiching the light-emitting layer.

6. The near-infrared light-emitting diode according to claim 5, characterized in that the material of the P-type epitaxial layer and the N-type epitaxial layer comprises gallium arsenide (GaAs) or aluminum gallium arsenide (AlGaAs), and the material of the light-emitting layer comprises indium gallium arsenide (InGaAs) or aluminum gallium arsenide (AlGaAs).

7. The near-infrared light-emitting diode according to claim 1, characterized in that the substrate is a gallium arsenide (GaAs) substrate or a silicon (Si) substrate.

8. A method for manufacturing a near-infrared light-emitting diode, A step of forming an epitaxial composite layer on a substrate having an emissive layer with an emission wavelength of 750 nanometers (nm) to 1000 nanometers (nm), The steps include: installing an upper electrode on the upper surface of the epitaxial composite layer; The process includes a step of installing a black photoresist that covers the epitaxial composite layer and exposes only the upper electrode, A method for manufacturing a near-infrared light-emitting diode, wherein the black photoresist absorbs light of visible wavelengths, and allows only infrared light to pass through the black photoresist and be emitted to the outside.

9. The step of installing the black photoresist involves installing the black photoresist with a thickness of approximately 1 to 5 micrometers (μm). The method for producing a near-infrared light-emitting diode according to claim 8, characterized in that the material of the black photoresist comprises 1-methoxy-2-propanol acetate and cyclohexanone.

10. The method for manufacturing a near-infrared light-emitting diode according to claim 8, characterized in that the step of forming the epitaxial composite layer is to form a P-type epitaxial layer and an N-type epitaxial layer sandwiching the light-emitting layer.

11. The material of the P-type epitaxial layer and the N-type epitaxial layer comprises gallium arsenide (GaAs) or aluminum gallium arsenide (AlGaAs). The method for manufacturing a near-infrared light-emitting diode according to claim 10, characterized in that the material of the light-emitting layer includes indium gallium arsenide (InGaAs) or aluminum gallium arsenide (AlGaAs).

12. The method for manufacturing a near-infrared light-emitting diode according to claim 8, characterized in that the substrate is a gallium arsenide (GaAs) substrate or a silicon (Si) substrate.

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