Optically coupled single chip structure and method for manufacturing the same

Abstract

To provide a structure of an optically coupled single chip capable of not only improving the external quantum efficiency of a light emitting diode but also reducing the entire volume of an optically coupled element, thinning a package element, and further reducing a manufacturing process time and cost, and to provide a method of manufacturing the same.SOLUTION: The lighting device includes a light-emitting unit 100, a light-receiving unit 200, and an electrical insulation layer 260, wherein the electrical insulation layer 260 is substantially connected to sides of the light-emitting unit 100 and the light-receiving unit 200 opposite to the electrical insulation layer 260. After the light-emitting unit 100 generates an optical signal according to an input signal, the optical signal passes through the electrical insulation layer 260 and is directly absorbed by the light-receiving unit 200 to be converted into an output signal.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to an optical coupling element and a manufacturing method thereof, and more particularly to a structure of an optical coupling single chip having both a light emitting unit and a light receiving unit on a single chip, and a manufacturing method thereof. [Background technology]

[0002] An optocoupler is an electronic device that uses light to transmit electrical signals. It typically consists of two chips with different functions, namely a light-emitting diode and a light-detecting unit (e.g., phototransistor, photodiode, etc.), to achieve electrical isolation and signal transmission. This design eliminates direct electrical connection between the input and output circuits, providing high-voltage isolation and noise suppression.

[0003] As shown in FIG. 1, conventional optocouplers 1 generally have a left-right packaging structure and a top-bottom packaging structure. In an optocoupler 1 with a left-right packaging structure, the light-emitting diode 10 and the photodetector unit 20 are respectively arranged at left and right positions facing each other inside the optocoupler 1. On the other hand, in an optocoupler 1 with a top-bottom packaging structure, the light-emitting diode 10 and the photodetector unit 20 are respectively arranged at top-bottom positions facing each other inside the optocoupler 1. However, in an optocoupler 1 with a left-right or top-bottom packaging structure, the light-emitting diode 10 and the photodetector unit 20 are separate, independent chips. In the optical signal transmission path, the optical signal passes through the air or packaging medium outside the light-emitting diode 10 before being received by the photodetector unit 20, which significantly reduces the external quantum efficiency of the light-emitting diode.

[0004] Meanwhile, in terms of physical structural arrangement, the two independent chips, the light-emitting diode 10 and the photodetector unit 20, must be mounted on a lead frame 30, respectively, and then assembled into the final device. Therefore, conventional optical couplers require space on the lead frame to accommodate the two independent chips. After assembly, they occupy a considerable volume. Furthermore, conventional optical couplers have problems such as complex manufacturing processes and high costs. The problems currently faced by the above-mentioned conventional optical couplers, such as the optical signal transmission path problem, excessive device volume, and high costs, require urgent improvement. Summary of the Invention

[0005] The main purpose of the present invention is to provide an innovative optically coupled single chip structure and manufacturing method thereof, which not only improves the external quantum efficiency of light emitting diodes, but also reduces the overall volume of the optically coupled device, realizes a thinner packaged device, and further reduces the manufacturing process time and cost.

[0006] To achieve the above object, the present invention provides an optically coupled single chip structure and a manufacturing method thereof. The optically coupled single chip structure includes a light emitting unit, a light receiving unit, and an electrical insulating layer. The electrical insulating layer is substantially connected to the sides of the light emitting unit and the light receiving unit facing the electrical insulating layer. After the light emitting unit forms an optical signal in response to an input signal, the optical signal passes through the electrical insulating layer and is directly absorbed by the light receiving unit and converted into an output signal.

[0007] In the optically coupled single chip structure embodiment of the present invention, the electrical insulating layer is an oxide, a nitride, or a transparent resin.

[0008] In an embodiment of the optically coupled single chip structure of the present invention, the oxide includes aluminum oxide (Al2O3) and silicon dioxide (SiO2).

[0009] In an embodiment of the optically coupled single chip structure of the present invention, the nitride comprises silicon nitride (SiN).

[0010] In an embodiment of the optically coupled single chip structure of the present invention, the transparent resin includes benzocyclobutene (BCB).

[0011] In the optically coupled single-chip structure embodiment of the present invention, the light-receiving unit has a pair of positive and negative electrodes that pass through the light-emitting unit and are electrically connected to the light-receiving unit.

[0012] In the optically coupled single-chip structure embodiment of the present invention, the light-emitting unit is fabricated by metal-organic chemical vapor deposition (MOCVD) and has a single-crystal structure.

[0013] In the optically coupled single-chip structure embodiment of the present invention, the light-receiving unit is a silicon PN junction diode.

[0014] To achieve the above object, the present invention provides a method for manufacturing an optically coupled single chip structure, which includes the following steps: First, a light-emitting unit is prepared. Next, a light-receiving unit is prepared. Next, a first electrical insulating layer is formed on one side of the light-emitting unit, and a second electrical insulating layer is formed on one side of the light-receiving unit. Finally, the first and second electrical insulating layers are bonded together to substantially connect the opposing sides of the first electrical insulating layer of the light-emitting unit and the second electrical insulating layer of the light-receiving unit. After the light-emitting unit forms an optical signal in response to an input signal, the optical signal passes through the first and second electrical insulating layers and is directly absorbed by the light-receiving unit and converted into an output signal.

[0015] In an embodiment of the method for manufacturing an optically coupled single-chip structure of the present invention, the steps of respectively forming the first and second electrical insulating layers include forming oxides on the light-emitting unit and the light-receiving unit, respectively.

[0016] In an embodiment of the method for manufacturing an optically coupled single-chip structure of the present invention, the step of forming oxides on the light-emitting unit and the light-receiving unit respectively includes the step of forming aluminum oxide (Al2O3) and silicon dioxide (SiO2) on the light-emitting unit and the light-receiving unit respectively.

[0017] In an embodiment of the method for manufacturing an optically coupled single chip structure of the present invention, the method further includes a step of forming a pair of positive and negative electrodes that penetrate the light-emitting unit and are electrically connected to the light-receiving unit.

[0018] In an embodiment of the method for manufacturing an optically coupled single-chip structure of the present invention, the step of providing a light-emitting unit includes the step of fabricating a light-emitting unit having a single crystal structure by metalorganic chemical vapor deposition.

[0019] In an embodiment of the method for manufacturing an optically coupled single-chip structure of the present invention, the step of providing a light-receiving unit includes the step of providing a silicon PN junction diode.

[0020] Those skilled in the art can 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 below. [Brief explanation of the drawings]

[0021] [Figure 1] Cross-sectional view showing two types of conventional optical coupling elements [Figure 2] 1 is a cross-sectional view showing the structure of an optically coupled single chip of the present invention and a method for manufacturing the same; [Figure 3] 1 is a cross-sectional view showing the structure of an optically coupled single chip of the present invention and a method for manufacturing the same; [Figure 4] 1 is a cross-sectional view showing the structure of an optically coupled single chip of the present invention and a method for manufacturing the same; [Figure 5] 1 is a cross-sectional view showing the structure of an optically coupled single chip of the present invention and a method for manufacturing the same; [Figure 6] 1 is a cross-sectional view showing the structure of an optically coupled single chip of the present invention and a method for manufacturing the same; [Figure 7] 1 is a cross-sectional view showing the structure of an optically coupled single chip of the present invention and a method for manufacturing the same; [Figure 8] 1 is a cross-sectional view showing the structure of an optically coupled single chip according to the present invention; [Figure 9] A flowchart showing the manufacturing process of the optically coupled single chip structure of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention will be described below through examples. Note that the examples of the present invention are merely examples of embodiments and are not intended to limit the present invention to the environments, applications, or specific aspects described in the examples. Therefore, the explanation of the examples is intended to explain the present invention, but does not limit the present invention. Note that components not directly related to the present invention are omitted and not shown in the embodiments and drawings. The dimensional relationships between the components in the drawings are intended to facilitate understanding and do not limit the actual dimensions.

[0023] The present invention discloses an optically coupled single-chip structure and its manufacturing method. As shown in FIG. 2A, a wafer is first prepared. The wafer may be, but is not limited to, a gallium arsenide (GaAs) wafer. A plurality of light-emitting units 100 are formed on the wafer. The light-emitting units 100 are light-emitting diodes (LEDs). In a specific embodiment, the LEDs have a substrate 110, which is a gallium arsenide substrate. A III-V epitaxial composite layer having a single crystal structure is formed on the substrate 110 by metal-organic chemical vapor deposition (MOCVD). The epitaxial composite layer includes, in order, an N-type doped epitaxial layer 120, a multiple quantum well (MQW) 130, a P-type doped epitaxial layer 140, and a gallium phosphide (GaP) epitaxial layer 150. The N-type doped epitaxial layer 120, the multiple quantum well 130, and the P-type doped epitaxial layer 140 of the epitaxial composite layer are primarily made of aluminum gallium arsenide (AlGaAs) ternary material. Next, referring to FIG. 2(B), an electrical insulating layer 160 is formed on the light-emitting unit 100. The electrical insulating layer 160 is an oxide, a nitride, or a transparent resin. In a preferred embodiment, when the electrical insulating layer 160 is an oxide, the electrical insulating layer 160 includes an aluminum oxide (Al2O3) layer 162 and a silicon dioxide (SiO2) layer 164. The aluminum oxide layer 162 is formed on the gallium phosphide (GaP) epitaxial layer 150. The silicon dioxide layer 164 is formed on the aluminum oxide layer 162. When the electrical insulating layer is a nitride, the nitride includes silicon nitride (SiN). When the electrical insulating layer is a transparent resin, the transparent resin includes benzocyclobutene (BCB).

[0024] Next, as shown in FIG. 3(A), another wafer is prepared. This wafer is a silicon wafer. A plurality of light-receiving units 200 are formed on this wafer. The light-receiving units 200 are photodiodes, for example, silicon PN junction diodes. In a specific embodiment, the photodiodes have a substrate 210. The substrate 210 is, but is not limited to, an N-type lightly doped silicon (Si) substrate. Next, a plurality of P-type heavily doped regions 220 and N-type heavily doped regions 230 are formed alternately on the substrate 210 by diffusion or ion implantation to form PN junctions of the photodiodes. Next, as shown in FIG. 3(B), an electrical insulating layer 260 is formed on the PN junctions of the light-receiving units 200, similar to FIG. 2(B). The electrical insulating layer 260 is an oxide, nitride, or transparent resin. The electrical insulating layer 260 is the same as the aforementioned electrical insulating layer 160, and a detailed description thereof will be omitted here. A preferred embodiment will be described below. Specifically, the electrical insulating layer 260 includes an aluminum oxide (Al2O3) layer 262 and a silicon dioxide (SiO2) layer 264. The aluminum oxide layer 262 is formed on the PN junction of the light-receiving unit 200. The silicon dioxide layer 264 is formed on the aluminum oxide layer 262.

[0025] Electrical insulating layers 160, 260 are formed on the surfaces of the light-emitting unit 100 and the light-receiving unit 200. In this embodiment, aluminum oxide layers 162, 262 and silicon dioxide layers 164, 264 are formed. Next, the silicon dioxide layer 164 of the gallium arsenide wafer having the plurality of light-emitting units 100 and the silicon dioxide layer 264 of the silicon wafer having the plurality of light-receiving units 200 are polished by chemical mechanical polishing and then surface activated. Then, the activated silicon dioxide layer 164 of the gallium arsenide wafer and the activated silicon dioxide layer 264 of the silicon wafer are aligned and bonded together. As shown in FIGS. 4 and 5, the oxide layers are bonded together under high temperature and pressure. As shown in the figures, after the two electrical insulating layers 160, 260 are bonded together, the two opposing sides of the electrical insulating layers 160, 260 of the light-emitting unit 100 and the light-receiving unit 200 are substantially connected. In a preferred embodiment, the total thickness of the bonded electrical insulating layers 160, 260 is preferably 1 micrometer or more. This thickness can be adjusted depending on the voltage resistance requirements of the optical coupling device. Next, as shown in FIG. 6, the original gallium arsenide substrate 110 used for epitaxial growth is removed using a chemical solution, leaving only the epitaxial composite layer including the N-type doped epitaxial layer 120, the multiple quantum well 130, the P-type doped epitaxial layer 140, and the gallium phosphide epitaxial layer 150. A single structure having both the light-emitting unit 100 and the light-receiving unit 200 is formed on one wafer.

[0026] FIG. 7 shows the state in which the wafer simultaneously carrying the light-emitting unit 100 and the light-receiving unit 200 is subjected to semiconductor processes such as mesa etching for element isolation, chemical vapor deposition, and electrode deposition to complete the fabrication of an optically coupled single chip. In the electrode design of the optically coupled single chip, the pair of positive and negative electrodes 170 (including a positive electrode 172 and a negative electrode 174) of the light-emitting unit 100 and the pair of positive and negative electrodes 270 (including a positive electrode 272 and a negative electrode 274) of the light-receiving unit 200 are disposed on one side of the light-emitting unit 100. The positive and negative electrodes 170 and 270 are electrically connected to the light-emitting unit 100 and the light-receiving unit 200, respectively. Taking the light-receiving unit 200 as an example, to fabricate the positive and negative electrodes 270 of the light-receiving unit 200, a pattern etching process is first performed to etch away part of the epitaxial layer of the light-emitting unit 100 and expose part of the light-receiving unit 200. Thereafter, an electrode deposition process is performed so that the positive and negative electrodes 270 penetrate the light-emitting unit 100 and are electrically connected to the light-receiving unit 200. Furthermore, this electrode layout design can be designed as a wire bonding type electrode or a flip chip type electrode depending on the device requirements, to meet the requirement of a thin device. In a preferred embodiment, the area of ​​the negative electrode 174 of the light-emitting unit 100 may be increased (not shown), thereby reflecting light that would otherwise be dissipated outside the light-emitting unit 100 back into the device, thereby improving device efficiency.

[0027] Finally, as shown in FIG. 8, a wafer dicing process is performed to simultaneously form an optically coupled single-chip structure having a light-emitting unit 100 and a light-receiving unit 200 on the single structure of the present invention. In this single-chip structure, light emitted from the epitaxial layer of the light-emitting diode passes directly from the inside through the electrical insulating layer and is absorbed by the light-receiving unit, thereby significantly improving the external quantum efficiency of the light-emitting diode. That is, in the optically coupled single-chip device of the present invention, after the light-emitting unit generates an optical signal in response to an external input signal, this optical signal passes through the electrical insulating layer and is directly absorbed by the light-receiving unit of the optically coupled single-chip device and converted into an output signal. The present invention overcomes the problem of reduced optical efficiency in conventional optically coupled devices, which occurs when the optical signal passes outside the light-emitting unit and is then absorbed by the light-receiving unit. Furthermore, the present invention significantly reduces the volume of the single-chip structure, meeting the requirement for thinness and further reducing manufacturing process time and costs.

[0028] 9 is a flowchart showing the manufacturing process of the optically coupled single-chip structure of the present invention. First, in step S01, a light-emitting unit is prepared. This light-emitting unit is a light-emitting diode. Next, in step S02, a light-receiving unit is prepared. Next, in step S03, an electrical insulating layer is formed on one side of the light-emitting unit, and an electrical insulating layer is formed on one side of the light-receiving unit. In step S04, the two electrical insulating layers are bonded together to substantially connect the opposing sides of the electrical insulating layers of the light-emitting unit and the light-receiving unit, thereby forming an optically coupled single-chip structure having both the light-emitting unit and the light-receiving unit on a single structure. Detailed descriptions of each unit can be found in the above content and are omitted here.

[0029] The above examples are intended to explain embodiments of the present invention and to explain the characteristic configurations of the present invention. The present invention is not limited to the above examples. 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 is based on the claims. [Explanation of symbols]

[0030] 1 Optical coupling element 10. Light-emitting diode 20 Optical detection unit 30 Lead Frame 100 light-emitting units 110 Substrate 120 N-type doped epitaxial layer 130 Multiple quantum wells 140 P-type doped epitaxial layer 150 Gallium phosphide (GaP) epitaxial layer 160 Electrical insulating layer 162 Aluminum oxide (Al2O3) layer 164 Silicon dioxide (SiO2) layer 170 Positive and negative electrodes 172 positive electrode 174 Negative electrode 200 Light receiving unit 210 Substrate 220 P-type heavily doped region 230 N-type heavily doped region 260 Electrical Insulation Layer 262 Aluminum oxide (Al2O3) layer 264 Silicon dioxide (SiO2) layer 270 Positive and negative electrodes 272 positive electrode 274 Negative electrode

Claims

1. An optically coupled single chip structure, A light-emitting unit; A light receiving unit; an electrical insulating layer substantially connected to the side surfaces of the light-emitting unit and the light-receiving unit facing the electrical insulating layer; The optically coupled single-chip structure, in which the light emitting unit forms an optical signal according to an input signal, and then the optical signal passes through the electrical insulating layer and is directly absorbed by the light receiving unit and converted into an output signal.

2. 2. The optically coupled single chip structure according to claim 1, wherein the electrical insulating layer is made of oxide, nitride, or transparent resin.

3. The oxide is aluminum oxide (Al ２ O ３ ) and silicon dioxide (SiO ２ 3. The optically coupled single chip structure according to claim 2, further comprising:

4. The optically coupled single chip structure of claim 2 , wherein the nitride comprises silicon nitride (SiN).

5. 3. The optically coupled single chip structure according to claim 2, wherein the transparent resin contains benzocyclobutene (BCB).

6. 2. The optically coupled single chip structure according to claim 1, wherein the light receiving unit has a pair of positive and negative electrodes that penetrate the light emitting unit and are electrically connected to the light receiving unit.

7. 2. The optically coupled single chip structure according to claim 1, wherein the light emitting unit is fabricated by metal-organic chemical vapor deposition (MOCVD) and has a single crystal structure.

8. 2. The optically coupled single chip structure as claimed in claim 1, wherein the light receiving unit is a silicon PN junction diode.

9. A method for manufacturing an optically coupled single chip structure, comprising: providing a light-emitting unit; providing a light receiving unit; forming a first electrical insulating layer on one side of the light-emitting unit and a second electrical insulating layer on one side of the light-receiving unit; and bonding the first electrical insulating layer and the second electrical insulating layer together to substantially connect opposing sides of the first electrical insulating layer of the light-emitting unit and the second electrical insulating layer of the light-receiving unit, a light-emitting unit that forms an optical signal according to an input signal, the optical signal passes through the first electrical insulating layer and the second electrical insulating layer, and is directly absorbed by the light-receiving unit and converted into an output signal;

10. 10. The manufacturing method according to claim 9, wherein the steps of forming the first electrical insulating layer and the second electrical insulating layer respectively include the steps of forming oxides on the light-emitting unit and the light-receiving unit, respectively.

11. The step of forming oxides on the light-emitting unit and the light-receiving unit includes forming aluminum oxide (Al ２ O ３ ) and silicon dioxide (SiO ２ 11. The method of claim 10, further comprising the step of forming a

12. 10. The manufacturing method according to claim 9, further comprising the step of forming a pair of positive and negative electrodes that penetrate the light-emitting unit and are electrically connected to the light-receiving unit.

13. 10. The manufacturing method according to claim 9, wherein the step of preparing the light-emitting unit includes a step of fabricating the light-emitting unit having a single crystal structure by metal organic chemical vapor deposition.

14. 10. The manufacturing method according to claim 9, wherein the step of preparing the light receiving unit includes the step of preparing a silicon PN junction diode.

Images