Photodiode and manufacturing method thereof

Abstract

The invention provides a photodiode and a manufacturing method thereof, and the manufacturing method of the photodiode comprises the following steps: providing a wafer which is provided with a plurality of photodiode structures; attaching a protective film on the wafer; cutting the protective film and the wafer to form a plurality of cutting channels on the protective film and the wafer to separate each of the plurality of photodiode structures; coating a shading solution on the protective film, and enabling the shading solution to cover each of the plurality of cutting channels; and curing the shading solution to form a shading sidewall completely covering each sidewall in the plurality of photodiode structures to block any light from penetrating the sidewalls.

Description

Technical Field

[0001] This invention relates to a photodiode and its manufacturing method, and more particularly to a photodiode with a light-shielding sidewall and its manufacturing method. Background Technology

[0002] A photodiode is an electronic component that converts external light signals into electrical signals. Its core function is to absorb external light, allowing it to detect the light signal and convert it into a measurable current. This conversion is crucial for various applications, such as optical communication, optical measurement, and imaging.

[0003] The way photodiodes absorb external light is by utilizing the semiconductor material (such as silicon) inside the diode. When a photon enters the photodiode and is absorbed, the photon's energy causes electrons in the valence band to jump to the conduction band, thus generating electron-hole pairs. These photogenerated carriers separate under the influence of the diode's built-in electric field and generate current.

[0004] However, in practical applications, traditional photodiodes are susceptible to interference from external light, which can easily penetrate the exposed sidewalls of the element and cause internal interference. This interference can affect the linearity of the photosensitive element and lead to calculation errors in subsequent applications of related components. To overcome these problems, the industry urgently needs an innovative photodiode architecture to mitigate the interference caused by erroneous signals generated after external light penetrates the sidewalls of the element. Summary of the Invention

[0005] The main objective of this invention is to provide an innovative photodiode and its manufacturing method. Compared with traditional optoelectronic components, the photodiode of this invention has a light-shielding sidewall that can block external light from entering the component, thereby improving the linearity of the component's light sensitivity and reducing problems caused by subsequent components generating erroneous signals.

[0006] To achieve the above objectives, the present invention provides a method for manufacturing a photodiode, the method comprising the following steps: providing a wafer having a plurality of photodiode structures; attaching a protective film to the wafer; dicing the protective film and the wafer to form a plurality of dicing channels on the protective film and the wafer to separate each of the plurality of photodiode structures; coating the protective film with a light-shielding solution to cover each of the plurality of dicing channels; and curing the light-shielding solution to form a light-shielding sidewall that completely covers the sidewalls of each of the plurality of photodiode structures to block any light from penetrating the sidewall.

[0007] In the method for manufacturing a photodiode in an embodiment of the present invention, the step of providing a wafer is to provide a wafer having a plurality of photodiode structures, wherein each photodiode in the plurality of photodiode structures has a substrate, an intrinsic region and a filter layer, wherein the intrinsic region is disposed on the substrate, and the filter layer covers the intrinsic region, selectively allowing only light of a specific wavelength to pass through and be received by the intrinsic region and generate an electrical signal accordingly by the intrinsic region.

[0008] In the method for manufacturing a photodiode in an embodiment of the present invention, after the step of forming a plurality of diced channels, the manufacturing method further includes the step of stretching a protective film to expand the width of each of the plurality of diced channels.

[0009] In the method for manufacturing a photodiode in an embodiment of the present invention, the step of expanding the width of each of the plurality of dicing channels is a step of forming each of the plurality of dicing channels with a width of 0.1 mm to 0.5 mm.

[0010] In the method for manufacturing a photodiode in an embodiment of the present invention, the step of coating a light-shielding solution is a step of coating an epoxy resin solution.

[0011] In the embodiment of the present invention, after the step of curing the light-shielding solution, the manufacturing method of the photodiode further includes the step of laser cutting each of a plurality of cutting channels.

[0012] The method for manufacturing a photodiode in an embodiment of the present invention further includes the step of providing an ultraviolet light irradiation protective film to separate the protective film from the wafer and form a plurality of photodiodes.

[0013] To achieve the above objectives, the present invention provides a photodiode comprising a photodiode structure and a light-shielding sidewall. The photodiode structure has a first conductivity type substrate, an intrinsic region disposed on the first conductivity type substrate, a second conductivity type semiconductor layer disposed on the intrinsic region, and a filter layer covering the second conductivity type semiconductor layer. The filter layer selectively allows only light of a specific wavelength to pass through and be received by the intrinsic region, thereby generating an electrical signal accordingly. The light-shielding sidewall completely covers the sidewall of the photodiode structure to block any light from passing through the sidewall and being received by the intrinsic region.

[0014] In the embodiments of the present invention, the photodiode has an epoxy resin sidewall as its light-shielding sidewall.

[0015] In the embodiments of the present invention, the photodiode emits ultraviolet light of a specific wavelength.

[0016] In the embodiments of the present invention, the photodiode emits ultraviolet light with a wavelength of less than 400 nanometers (nm).

[0017] In the embodiments of the present invention, the photodiode has a band-pass filter layer.

[0018] In an embodiment of the present invention, the photodiode further includes an anti-reflection layer formed on the filter layer.

[0019] Other objects of the invention, as well as the technical means and embodiments of the invention, will be apparent to those skilled in the art upon referring to the accompanying drawings and the embodiments described below. Attached Figure Description

[0020] Figure 1 An enlarged cross-sectional view of a wafer and a photodiode structure on the wafer, according to an embodiment of the present invention, is shown. Figure 2 A schematic diagram of the protective film being attached to a wafer according to an embodiment of the present invention is shown; Figure 3 A cross-sectional view of a protective film attached to a photodiode structure according to an embodiment of the present invention is shown; Figure 4 A schematic diagram of a cutting wheel cutting a protective film and a wafer according to an embodiment of the present invention is shown; Figure 5 A top view of the diced paths on the wafer surface according to an embodiment of the present invention is shown; Figure 6 A cross-sectional view of an adjacent photodiode structure according to an embodiment of the present invention is shown; Figure 7 A schematic diagram illustrating the application of a light-shielding solution to a wafer surface according to an embodiment of the present invention is shown; Figure 8 It shows Figure 7 Partial cross-sectional view of line segment AA' in the middle; Figure 9 A schematic diagram of a photodiode according to an embodiment of the present invention is shown; and Figure 10 A schematic diagram of the process steps of a photodiode according to an embodiment of the present invention is shown. Detailed Implementation

[0021] The present invention will be explained below through embodiments. These embodiments are not intended to limit the implementation of the invention to any specific environment, application, or special method as described in the embodiments. Therefore, the descriptions of the embodiments are merely illustrative of the invention and not intended to limit it. It should be noted that in the following embodiments and drawings, elements not directly related to the present invention have been omitted and are not shown, and the dimensional relationships between the elements in the drawings are for ease of understanding only and are not intended to limit the actual scale.

[0022] Please see Figure 1 The figure shows an enlarged cross-sectional view of a wafer and a photodiode structure on the wafer, according to an embodiment of the present invention. As shown, in this embodiment, wafer 1 can be a silicon wafer, and wafer 1 has multiple uncut photodiode structures 100. Each photodiode structure 100 includes a first conductive substrate 110, an intrinsic region 120, a second conductive semiconductor layer 130, a filter layer 140, and an electrode 150. The first conductive substrate 110 can be an N-type doped semiconductor layer, such as, but not limited to, silicon-doped gallium nitride (GaN) or silicon carbide (SiC) semiconductor layers. The intrinsic region 120 is disposed on the first conductive substrate 110, covering the first conductive substrate 110, and the intrinsic region 120 can be an undoped or lightly doped semiconductor layer, such as, but not limited to, aluminum gallium nitride (AlGaN), gallium nitride (GaN), or silicon carbide (SiC) semiconductor layers, to receive light of a specific wavelength, such as absorbing ultraviolet light with a wavelength range less than 400 nanometers (nm) to generate an electrical signal accordingly. The second conductivity semiconductor layer 130 covers the intrinsic region 120 and can be a P-type doped semiconductor layer, such as, but not limited to, magnesium-doped gallium nitride (GaN) or aluminum gallium nitride (AlGaN) semiconductor layers.

[0023] Furthermore, the filter layer 140 is typically a band-pass filter layer covering the second conductive semiconductor layer 130, selectively allowing only light of specific wavelengths (e.g., ultraviolet light with wavelengths less than 400 nanometers (nm)) to pass through and be received by the intrinsic region 120, while blocking light of other wavelengths, such as visible or infrared light. The filter layer 140 is typically composed of multiple layers of dielectric materials stacked together, which are typically dielectrics with alternating high and low refractive indices, such as silicon dioxide (SiO2), titanium dioxide (TiO2), or silicon nitride (Si3N4). In a preferred embodiment, an anti-reflection layer (not shown) formed thereon is also included above the filter layer 140. The anti-reflection layer can enhance the transmittance of light in specific wavelength bands, improve photon utilization, and minimize the reflection loss of incident light, thereby improving the photoelectric conversion efficiency of the device. An electrode 150 is disposed on and electrically connected to the second conductive semiconductor layer 130. The electrode 150 can be, but is not limited to, aluminum.

[0024] Please refer to both together. Figure 2 and Figure 3 The diagram illustrates attaching a protective film 2 to wafer 1. This protective film 2 can be a UV-curable adhesive tape. The characteristic of this protective film 2 is that it has high adhesion and is not easily detached during use, but during subsequent adhesive removal, after UV irradiation, the adhesion of the protective film decreases, achieving the purpose of adhesive removal without leaving any residue. It should be noted that, as... Figure 3 As shown, there is an invalid region 160 between two adjacent photodiode structures 100 on wafer 1. This invalid region 160 is doped with a second conductivity type (N-type) dopant to isolate the components on the wafer from each other, and is also used as a dicing track for subsequent component dicing.

[0025] Please refer to both together. Figure 4 , Figure 5 and Figure 6 ,in Figure 4 The diagram shows that a cutting wheel 3 is used to cut the protective film 2 and the wafer 1 at positions corresponding to the invalid region 160, forming multiple cutting channels 10 on the protective film 2 and the wafer 1 to separate the photodiode structures 100. In a preferred embodiment, after forming the cutting channels 10, the protective film 2 can be stretched to further expand the width of each cutting channel 10, that is, the distance between two adjacent photodiode structures 100 separated by the cutting channels 10. For example, in a preferred embodiment, the width of the cutting channel 10 is 0.1~0.5 mm. Figure 5 As shown. Among them, Figure 6 yes Figure 5 A cross-sectional view of the AA' segment shown. Figure 6 This shows two adjacent photodiode structures 100 separated by a cutaway path 10. Please refer to the combined section below. Figure 7 and Figure 8 ,in, Figure 7 The diagram shows the application of a light-shielding solution, which can be a liquid epoxy resin 20, onto a protective film 2. Furthermore, Figure 8 yes Figure 7 A cross-sectional view of the AA' segment shown. Figure 8 The diagram shows a dicing 10 between two adjacent photodiode structures 100 filled with liquid epoxy resin 20. After the liquid epoxy resin is injected, excess epoxy resin is removed from the surface of the wafer 1, for example, by wiping with a sponge. Then, a heat curing process is performed to cure the epoxy resin 20 in the dicing 10. See also... Figure 9 Next, the cured epoxy resin 20 in each cut 10 is cut using a laser or a conventional cutting wheel. Finally, an ultraviolet light irradiation protective film 2 is provided to separate the protective film 2 from the wafer 1, thereby forming multiple photodiodes 101 that are separated from each other.

[0026] The photodiode 101 of the present invention is characterized by including a light-shielding sidewall formed of opaque epoxy resin 20, which completely covers the sidewall of the edge of the photodiode structure 100 to block any light from passing through the light-shielding sidewall and being received by the intrinsic region 120, thereby reducing the interference of external side light on the intrinsic region 120, improving the linearity of the element's photosensitivity and reducing the error of subsequent element calculations.

[0027] Please see Figure 10 The diagram illustrates the process steps of the photodiode of the present invention. First, in step S01, a wafer is provided having multiple photodiode structures. Next, in step S02, a protective film is attached to the wafer. In step S03, the protective film and the wafer are diced to form multiple dicing channels on both to separate the individual photodiode structures. Then, in step S04, a light-shielding solution is coated onto the protective film, covering each dicing channel. Finally, in step S05, the light-shielding solution is cured to form light-shielding sidewalls that completely cover the sidewalls of each photodiode structure, blocking any light from penetrating the sidewalls. Descriptions of the relevant components are as described above and will not be repeated here.

[0028] The above embodiments are merely illustrative of the implementation methods of the present invention and to explain the technical features of the present invention, and are not intended to limit the scope of protection of the present invention. Any changes or equivalent arrangements that can be easily made by those skilled in the art are within the scope of the present invention, and the scope of protection of the present invention should be determined by the scope of the claims.

[0029] [Symbol Explanation] 1 wafer 2 Protective film 3 cutting wheel 10 cutting channels 20 epoxy resin 100 photodiode structure 101 photodiode 110 First Conductivity Substrate 120th Military District 130 Second conductivity type semiconductor layer 140 filter layers 150 electrodes 160 invalid zone AA' line segment

Claims

1. A method for manufacturing a photodiode, the method comprising: A wafer is provided having a plurality of photodiode structures on it; A protective film is attached to the wafer; The protective film and the wafer are cut to form a plurality of cleavage paths on the protective film and the wafer to separate each of the plurality of photodiode structures; A light-shielding solution is applied to the protective film so that the light-shielding solution covers each of the plurality of cutting channels; as well as The light-shielding solution is cured to form a light-shielding sidewall that completely covers the sidewall of each of the plurality of photodiode structures, thereby blocking any light from penetrating the sidewall.

2. The manufacturing method according to claim 1, wherein, The step of providing a wafer is to provide a wafer having multiple photodiode structures, each of the multiple photodiode structures having a substrate, an intrinsic region, and a filter layer, wherein the intrinsic region is disposed on the substrate, and the filter layer covers the intrinsic region, selectively allowing only light of a specific wavelength to pass through and be received by the intrinsic region, and the intrinsic region correspondingly generates an electrical signal.

3. The manufacturing method according to claim 1, wherein, After forming the plurality of cuts, the manufacturing method further includes the step of stretching the protective film to expand the width of each of the plurality of cuts.

4. The manufacturing method according to claim 3, wherein, The step of expanding the width of each of the plurality of cutting channels is the step of forming the width of each of the plurality of cutting channels to be 0.1 mm to 0.5 mm.

5. The manufacturing method according to claim 1, wherein, The step of applying the light-shielding solution is the same as the step of applying the epoxy resin solution.

6. The manufacturing method according to claim 1, wherein, After the step of curing the light-shielding solution, the manufacturing method further includes the step of laser cutting each of the plurality of cut channels.

7. The manufacturing method according to claim 1, further comprising the step of providing ultraviolet light to irradiate the protective film to separate the protective film from the wafer and form a plurality of photodiodes.

8. A photodiode, the photodiode comprising: A photodiode structure has a first conductivity type substrate; an intrinsic region disposed on the first conductivity type substrate; a second conductivity type semiconductor layer disposed on the intrinsic region; and a filter layer covering the second conductivity type semiconductor layer, selectively allowing only light of a specific wavelength to pass through and be received by the intrinsic region, thereby generating an electrical signal accordingly; and A light-shielding sidewall completely covers the sidewall of the photodiode structure to block any light from passing through the sidewall and being received by the intrinsic region.

9. The photodiode according to claim 8, wherein, The light-shielding sidewall is an epoxy resin sidewall.

10. The photodiode according to claim 8, wherein, The light of that specific wavelength is ultraviolet light.

11. The photodiode according to claim 10, wherein, The wavelength of the ultraviolet light is less than 400 nanometers.

12. The photodiode according to claim 8, wherein, The filtering layer is a bandpass filtering layer.

13. The photodiode according to claim 8, wherein the photodiode further comprises an anti-reflection layer formed on the filter layer.

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