Stretchable LED chip structure and preparation method

Abstract

The invention discloses a preparation method of a stretchable LED chip, and the method comprises the steps: providing a substrate needed by growth, depositing an epitaxial layer on the substrate, and enabling the epitaxial layer to comprise a buffer layer, a sacrificial layer, an n-type ohmic contact layer, an n-type doped layer, a quantum well layer, a p-type doped layer and a p-type ohmic contact layer which are sequentially arranged; evaporating a back metal electrode on the whole surface of the epitaxial layer; a thermoplastic plastic film is arranged on the back metal electrode; the substrate is removed, and a plurality of holes are formed in the thermoplastic plastic film; preparing an electrode on the front surface of the epitaxial layer to form an integral sheet layer consisting of a plurality of LED chips; separating the integral sheet layer to form a single LED chip; the flexible stretchable conductive material is used for connecting the plurality of single LED chips, so that the prepared LED chips have high stretchability, the phototherapy instrument has certain tensile strength, and the comfort level of the phototherapy instrument at multi-curved-surface positions such as elbow joints and knee joints can be greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of smart wearables, and in particular to a stretchable LED chip structure and a preparation method thereof. Background Art

[0002] LED light-emitting diodes can efficiently convert electrical energy into light energy, and have the advantages of small size, long life, low power consumption, high brightness, and easy integration. They have a wide range of uses in modern society, such as lighting, flat panel displays, and medical devices.

[0003] In the field of smart wearables, especially wearable phototherapy devices, because they are used close to the skin, existing phototherapy devices may lack tensile strength, and the comfort of phototherapy devices for elbow joints, knee joints and other positions may be very poor. Summary of the invention

[0004] The object of the present invention is to overcome at least one defect of the prior art and provide a stretchable LED chip structure and a preparation method thereof.

[0005] The present application provides a method for preparing a stretchable LED chip, comprising: Providing a substrate required for growth, depositing an epitaxial layer on the substrate, wherein the epitaxial layer includes a buffer layer, a sacrificial layer, an n-type ohmic contact layer, an n-type doped layer, a quantum well layer, a p-type doped layer and a p-type ohmic contact layer arranged in sequence; Vapor-depositing a back metal electrode on the entire surface of the epitaxial layer; A thermoplastic plastic film is disposed on the back metal electrode; The substrate is removed, and a plurality of holes are provided in the thermoplastic film; Prepare an electrode on the front side of the epitaxial layer to form an integral sheet consisting of a plurality of LED chips; Separating the whole sheet layer to form the single LED chip; The plurality of individual LED chips are connected using a flexible stretchable conductive material.

[0006] Preferably, the thickness of the holes is the same as the thickness of the thermoplastic film.

[0007] Preferably, the thermoplastic plastic film is a PEN film, and the thickness of the thermoplastic plastic film is in the range of 50 μm to 70 μm.

[0008] Preferably, the thermoplastic plastic film is a PET film, and the thickness of the thermoplastic plastic film is in the range of 25 μm to 35 μm.

[0009] Preferably, the size of the holes ranges from 50 μm to 70 μm.

[0010] The present application also provides a stretchable LED chip structure, which is prepared by the preparation method described in any one of items 1 to 5 above, including: a plurality of electrically connected LED chips; The LED chip includes an epitaxial layer, and the epitaxial layer includes a buffer layer, a sacrificial layer, an n-type ohmic contact layer, an n-type doping layer, a quantum well layer, a p-type doping layer and a p-type ohmic contact layer arranged in sequence; The entire surface of the epitaxial layer is provided with a back metal electrode; A thermoplastic plastic film is provided on the back metal electrode, and the thermoplastic plastic film is provided with a plurality of holes; A plurality of electrodes are arranged on the epitaxial layer, a plurality of gold wires are connected between the plurality of LED chips, and the gold wires are connected to the electrodes.

[0011] Preferably, two pairs of electrodes are correspondingly arranged on one side of the LED chip, and the gold wires and the electrodes are located on the same side of the LED chip and are connected to each other.

[0012] Preferably, a pair of electrodes are respectively arranged on the front and back sides of the LED chip, and between two adjacent LED chips, one end of the gold wire is connected to the electrode on the front side of the LED chip, and the other end of the gold wire is connected to the electrode on the back side of the LED chip.

[0013] Preferably, the gold wire has an arc-shaped cross section.

[0014] Preferably, the gold wire includes a plurality of interconnected inverted V-shaped connecting parts.

[0015] Compared with the prior art, the gold wire connection structure between the two chips adopted in the present invention enables the prepared LED chip to have higher stretchability, especially in wearable phototherapy devices, which are used close to the skin, so that the phototherapy device has a certain tensile strength, which will greatly improve the comfort of phototherapy devices for multi-curved positions such as elbow joints and knee joints. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention.

[0017] Figure 1 is a flow chart of the method for preparing a stretchable LED chip provided by the present invention; Figure 2 It is a schematic diagram of the structure of the LED chip provided by the present invention; Figure 3 is a schematic diagram of a first embodiment of gold wire connection of the present invention; Figure 4is a schematic diagram of a second embodiment of the gold wire connection of the present invention; Figure 5 It is a schematic diagram of the third embodiment of the gold wire connection of the present invention.

[0018] Reference numerals include: LED chip 1; epitaxial layer 11; buffer layer 111; sacrificial layer 112; n-type ohmic contact layer 113; n-type doped layer 114; quantum well layer 115; p-type doped layer 116; p-type ohmic contact layer 117; back metal electrode 118; thermoplastic film 119; hole 1191; Electrode 2; Gold wire 3; connecting portion 31. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0021] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0022] like Figure 1 As shown, this embodiment provides a method for preparing a stretchable LED chip 1, including providing a substrate required for growth; preferably, the substrate is made of sapphire, which is currently the most commonly used substrate material. Sapphire substrate has the advantages of mature preparation technology, low price, easy cleaning, and high stability at high temperature.

[0023] Deposited on the substrate is an epitaxial layer 11, which includes a buffer layer 111, a sacrificial layer 112, an n-type ohmic contact layer 113, an n-type doped layer 114, a quantum well layer 115, a p-type doped layer 116 and a p-type ohmic contact layer 117 arranged in sequence; specifically, the epitaxial layer 11 is prepared by MOCVD, that is, by metal organic chemical vapor deposition, gaseous metal organic compounds and hydride precursors are introduced into a high-temperature reaction chamber, and chemical reactions occur on the surface of the substrate to generate solid semiconductor materials. The buffer layer 111 is usually located between the substrate and the epitaxial layer 11, and is used to improve the quality of the epitaxial layer 11, reduce defects, and adjust the doping concentration, which can significantly improve the performance and reliability of the final device. Further, the thickness of the buffer layer 111 ranges from 0.5 μm to 1 μm. The main functions of the sacrificial layer 112 are protection, support and isolation, which can significantly improve the reliability and performance of the device; further, the sacrificial layer 112 is made of silicon oxide. The n-type ohmic contact layer 113 allows electrons to easily enter the conduction band of the semiconductor from the metal, forming a low-resistance current channel. The n-type ohmic contact layer 113 is made of titanium. The n-type doping layer 114 is used to introduce free electrons, thereby improving conductivity; the n-type doping layer 114 is usually made of silicon. The quantum well layer 115 is used to control and optimize carriers using the quantum confinement effect, thereby improving conductivity; further, the quantum trap layer uses SiGe as the quantum well material and Si as the barrier material, thereby significantly improving the mobility of electrons, reducing resistance, and improving the switching speed and frequency response of the device. The p-type doping layer 116 is used to introduce additional hole carriers, and the material is selected from silicon, which can significantly improve conductivity. The p-type ohmic contact layer 117 is used to achieve a good electrical connection between a low-resistance, high-conductivity p-type semiconductor and a metal. The p-type ohmic contact layer 117 uses nickel as the bottom layer to provide good adhesion and low contact resistance; gold is used as the top layer to provide low resistance and oxidation resistance.

[0024] The back metal electrode 2118 is deposited on the entire surface of the epitaxial layer 11 by PVD, thereby providing a low-resistance contact point for the introduction or extraction of current, and also for heat dissipation, mechanical support and protection. Further, the back metal electrode 2118 has a thickness ranging from 10 μm to 15 μm.

[0025] A thermoplastic film 119 is disposed on the back metal electrode 2118; the thickness of the hole 1191 is the same as the thickness of the thermoplastic film 119. Preferably, the thermoplastic film 119 is a PEN or PET film. Preferably, the thermoplastic film 119 is a PEN film, and the thickness of the thermoplastic film 119 is in the range of 50 μm to 70 μm. Preferably, the thermoplastic film 119 is a PET film, and the thickness of the thermoplastic film 119 is in the range of 25 μm to 35 μm.

[0026] The substrate is removed and a plurality of holes 1191 are provided in the thermoplastic film 119; preferably, the size of the holes 1191 ranges from 50 μm to 70 μm, so as to optimize heat dissipation, light output and environmental adaptability.

[0027] An electrode 2 is prepared on the front side of the epitaxial layer 11 to form an integral layer composed of a plurality of LED chips 1; the integral layer is separated to form a single LED chip 1; a flexible and stretchable conductive material is used to connect the plurality of single LED chips 1, so that the prepared LED chip 1 has high stretchability, especially in a wearable phototherapy device that is used close to the skin, so that the phototherapy device has a certain tensile strength, which will greatly improve the comfort of the phototherapy device for multi-curved positions such as the elbow joint and the knee joint.

[0028] like Figures 2 to 4 As shown, the present application also provides a stretchable LED chip 1 structure, which is prepared by the preparation method described above, including a plurality of electrically connected LED chips 1; the LED chip 1 includes an epitaxial layer 11, and the epitaxial layer 11 includes a buffer layer 111, a sacrificial layer 112, an n-type ohmic contact layer 113, an n-type doped layer 114, a quantum well layer 115, a p-type doped layer 116 and a p-type ohmic contact layer 117 arranged in sequence; a back metal electrode 2118 is provided on the entire surface of the epitaxial layer 11; a thermoplastic plastic film 119 is provided on the back metal electrode 2118, and the thermoplastic plastic film 119 is provided with a plurality of holes 1191; a plurality of electrodes 2 are provided on the epitaxial layer 11, and a plurality of gold wires 3 are connected between the plurality of the LED chips 1, and the gold wires 3 are connected to the electrodes 2.

[0029] Preferably, two pairs of electrodes 2 are correspondingly arranged on one side of the LED chip 1, and the gold wire 3 and the electrodes 2 are located on the same side of the LED chip 1 and are connected to each other. Furthermore, the cross section of the gold wire 3 is arc-shaped, so that the LED chip 1 has a certain ductility.

[0030] Preferably, the gold wire 3 includes a plurality of mutually connected inverted V-shaped connecting portions 31 , so that the LED chip 1 has a certain degree of ductility.

[0031] Preferably, a pair of electrodes 2 are respectively provided on the front and back sides of the LED chip 1 , and between two adjacent LED chips 1 , one end of the gold wire 3 is connected to the electrode 2 on the front side of the LED chip 1 , and the other end of the gold wire 3 is connected to the electrode 2 on the back side of the LED chip 1 .

[0032] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0033] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a stretchable LED chip, characterized in that: include, Providing a substrate required for growth, depositing an epitaxial layer on the substrate, wherein the epitaxial layer includes a buffer layer, a sacrificial layer, an n-type ohmic contact layer, an n-type doped layer, a quantum well layer, a p-type doped layer and a p-type ohmic contact layer arranged in sequence; Vapor-depositing a back metal electrode on the entire surface of the epitaxial layer; A thermoplastic plastic film is disposed on the back metal electrode; The substrate is removed, and a plurality of holes are provided in the thermoplastic film; Prepare an electrode on the front side of the epitaxial layer to form an integral sheet consisting of a plurality of LED chips; Separating the whole sheet layer to form the single LED chip; The plurality of individual LED chips are connected using a flexible stretchable conductive material.

2. The method for preparing a stretchable LED chip according to claim 1, characterized in that: The thickness of the holes is the same as the thickness of the thermoplastic film.

3. The method for preparing a stretchable LED chip according to claim 2, characterized in that: The thermoplastic plastic film is a PEN film, and the thickness of the thermoplastic plastic film is in the range of 50 μm to 70 μm.

4. The method for preparing a stretchable LED chip according to claim 2, characterized in that: The thermoplastic plastic film is a PET film, and the thickness of the thermoplastic plastic film is in the range of 25 μm to 35 μm.

5. The method for preparing a stretchable LED chip according to claim 1, characterized in that: The size of the pores ranges from 50 μm to 70 μm.

6. A stretchable LED chip structure, prepared by the preparation method described in any one of 1 to 5 above, characterized in that: include, a plurality of electrically connected LED chips; The LED chip includes an epitaxial layer, and the epitaxial layer includes a buffer layer, a sacrificial layer, an n-type ohmic contact layer, an n-type doping layer, a quantum well layer, a p-type doping layer and a p-type ohmic contact layer arranged in sequence; The entire surface of the epitaxial layer is provided with a back metal electrode; A thermoplastic plastic film is provided on the back metal electrode, and the thermoplastic plastic film is provided with a plurality of holes; A plurality of electrodes are arranged on the epitaxial layer, a plurality of gold wires are connected between the plurality of LED chips, and the gold wires are connected to the electrodes.

7. The stretchable LED chip structure according to claim 6, characterized in that: Two pairs of electrodes are correspondingly arranged on one side of the LED chip, and the gold wires and the electrodes are located on the same side of the LED chip and are connected to each other.

8. The stretchable LED chip structure according to claim 6, characterized in that: A pair of electrodes is respectively arranged on the front and back sides of the LED chip. Between two adjacent LED chips, one end of the gold wire is connected to the electrode on the front side of the LED chip, and the other end of the gold wire is connected to the electrode on the back side of the LED chip.

9. The stretchable LED chip structure according to claim 7, characterized in that: The gold wire has an arc-shaped cross section.

10. The stretchable LED chip structure according to claim 7, characterized in that: The gold wire includes a plurality of mutually connected inverted V-shaped connecting parts.

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