Photodetector element

Abstract

To provide an innovative photodetector that improves the conventional problems of false signals and reduced detection accuracy due to poor filtering.SOLUTION: A light receiving area is located on a substrate. A filter layer covers the light receiving area and selectively transmits only light of a specific wavelength to be received in the light receiving area, while blocking light of other wavelengths. A chamfer structure is formed on each of the two side edges of the substrate. The filter layer covers the chamfer structure on each side edge and blocks light of other wavelengths from passing through the two side edges of the substrate and being received in the light receiving area.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a photodetector element, and more particularly to a photodetector element having a chamfered structure formed on its side edge. [Background technology]

[0002] A bandpass filter (BPF) is an optical element that selectively passes light in a specific wavelength range and blocks light in other wavelength ranges. Such filters are very useful in optical sensing devices because they can isolate and detect light of specific wavelengths or frequencies within a range, and have applications in technologies such as biomedical imaging and environmental monitoring.

[0003] Optical bandpass filters operate on the principle of optical interference and reflection and typically consist of a transparent substrate and a multilayer film structure. This multilayer film structure is made up of alternating layers of different materials with specific optical thicknesses, providing high transmittance for certain wavelengths and high reflectance for other wavelengths. When light is shone on the surface of the filter, it enters the filter's multilayer film structure. Light interference and reflection occur at the interfaces in the multilayer film structure. Because different wavelengths of light propagate at different speeds through different materials, interference in the multilayer film structure strengthens some wavelengths through phase addition and weakens others through phase cancellation. With proper design, the filter's multilayer film structure can form a resonant cavity, enhancing certain wavelengths of light while reflecting or absorbing others, thereby allowing certain wavelengths of light to pass through the filter, a so-called "bandpass" effect.

[0004] However, while conventional sensing devices can use bandpass filters to filter out specific wavelengths of light, some light still enters the sensing device, generating photocurrent at the interface of the photodiode, which adversely affects detection accuracy. To overcome the above-mentioned problems, developing an innovative optical detection structure that can improve the filtering problem has become an urgent task in the industry. Summary of the Invention

[0005] A primary object of the present invention is to provide an innovative photodetector element that improves upon the conventional problems of false signals and reduced detection accuracy due to poor filtering.

[0006] To achieve the above object, the present invention provides a photodetector element including a substrate, a light-receiving region, and a filter layer. The light-receiving region is disposed on the substrate. The filter layer covers the light-receiving region, selectively transmitting only light of a specific wavelength to be received by the light-receiving region and blocking light of other wavelengths. A chamfered structure is formed on each of the two side edges of the substrate. The filter layer covers the chamfered structure on each side edge and blocks light of other wavelengths from passing through the two side edges of the substrate and being received by the light-receiving region.

[0007] In an embodiment of the present invention, the filter layer of the photodetector element is a band pass filter layer.

[0008] In an embodiment of the present invention, the bandpass filter layer of the photodetector element is a composite layer of tantalum pentoxide (Ta2O5) and silicon dioxide (SiO2).

[0009] In an embodiment of the present invention, the maximum depth of the chamfered structure of the photodetector is less than about 1 / 4 of the thickness of the substrate.

[0010] In an embodiment of the present invention, the depth of the chamfered structure of the photodetector element is about 40 μm.

[0011] In an embodiment of the present invention, the light-detecting element further includes a photomask layer covering a portion of the filter layer above the chamfered structure.

[0012] In an embodiment of the present invention, the material of the photomask layer of the light-detecting element includes a color photoresist.

[0013] In an embodiment of the present invention, the material of the photomask layer of the photodetector element is one selected from the group consisting of aluminum, titanium, copper, silver, gold, and alloys thereof.

[0014] In an embodiment of the present invention, the light of a specific wavelength that is transmitted and received by the light receiving area of the photodetector element is ultraviolet light in the wavelength range of approximately 100 nm to 400 nm.

[0015] In an embodiment of the present invention, the light-receiving region of the photodetector element includes a silicon diode photosensitive structure.

[0016] In an embodiment of the present invention, the substrate of the photodetector element is a silicon substrate.

[0017] 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]

[0018] [Figure 1] 1 is a schematic diagram illustrating the structure of a photodetector element according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0019] 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.

[0020] FIG. 1 is a schematic diagram illustrating the structure of a photodetector according to an embodiment of the present invention. As shown in FIG. 1, in this embodiment, the photodetector 1 includes a substrate 10, a light-receiving region 20, a filter layer 30, an upper electrode 40, and a lower electrode 50. The substrate 10 is a lower support for the photodetector 1 and is typically made of an optically transparent material that transmits light. The substrate 10 is typically made of a material with good optical transparency, such as silicon or quartz. In this embodiment of the present invention, silicon is used as the material for the substrate 10. The thickness of the substrate 10 can be adjusted according to specific applications and design requirements and is typically in the range of several hundred micrometers (μm) to several millimeters (mm). In this embodiment of the present invention, the thickness of the silicon substrate 10 is approximately 400 micrometers.

[0021] As shown in FIG. 1, the light-receiving region 20 is a central region disposed on the substrate 10 as a portion for detecting optical signals. The light-receiving region 20 is typically a P / N diode photosensitive structure for receiving light of a specific wavelength. Specifically, the light-receiving region 20 of the present invention includes a silicon diode photosensitive structure. The filter layer 30 is a band-pass filter layer covering the light-receiving region 20, selectively transmitting only light of a specific wavelength to be received by the light-receiving region 20 and blocking light of other wavelengths. In an embodiment of the present invention, the filter layer 30 transmits only ultraviolet light of a specific wavelength in the range of approximately 100 nm to 400 nm and blocks light of other wavelengths. For example, visible light and far-infrared light are blocked from being absorbed by the light-receiving region 20. The filter layer 30 has a multilayer film structure. In the present invention, the filter layer 30 is a composite layer of tantalum pentoxide (Ta2O5) and silicon dioxide (SiO2). The upper electrode 40 is disposed within the filter layer 30. A bottom electrode 50 is disposed on the backside of the substrate 10. These electrodes apply an electric field to control the optical properties of the filter layer 30. The center wavelength or bandwidth of the filter is tuned by varying the refractive index of the dielectric layers within the filter layer with a voltage.

[0022] A feature of the photodetector 1 of the present invention is that, as shown by the dotted line in FIG. 1 , a chamfered structure 12 is formed on each of the two side edges of the substrate 10 to reduce interference in photodetection. In a specific embodiment, the chamfered structure 12 is formed by isotropically etching the substrate 10 using a wet etching process. The maximum depth of the chamfered structure 12 on the substrate 10, measured from the top surface of the substrate 10, is less than approximately ¼ of the thickness of the substrate 10. Specifically, when the thickness of the substrate 10 is approximately 400 micrometers, the depth of the chamfered structure 12 on the substrate is 0 to 100 micrometers. In a preferred embodiment of the present invention, the depth of the chamfered structure 12 on the substrate 10 may be 40 micrometers. The maximum depth of the chamfered structure 12 on the substrate 10 is greater than the thickness of the light-receiving region 20.

[0023] 1, the filter layer 30 covers the entire substrate 10 and the light-receiving region 20. Therefore, the filter layer 30 conformally covers each of the chamfered structures 12 on the sides of the substrate 10. Because the chamfered structures 12 have a chamfered profile, the two sides of the filter layer 30 have a chamfered profile that is more downwardly inclined than the central region. The downwardly inclined portions on the two sides of the filter layer 30 can effectively prevent light of wavelengths other than a specific wavelength, such as ultraviolet light, from passing through the sidewalls of the substrate, entering the interior of the substrate, and being received by the light-receiving region, thereby generating an erroneous signal.

[0024] The photodetector 1 of the present invention further includes a photomask layer 60 covering a portion of the filter layer 30 on the chamfered structure 12 to further reduce interference in photodetection. The material of the photomask layer 60 includes a color photoresist or a metal material, which can further block external light from passing through the sidewall of the substrate. The color photoresist of the photomask layer 60 may be, but is not limited to, zinc sulfide (ZnS), cadmium selenide (CdSe), etc. Meanwhile, the metal material of the photomask layer 60 is formed on the portion of the filter layer 30 on the chamfered structure 12 using sputtering or physical vapor deposition. The metal material is one selected from the group consisting of aluminum, titanium, copper, silver, gold, and alloys thereof.

[0025] As described above, the photodetector according to the present invention has a chamfered structure formed by etching the edge of the element, and the surface is covered with a filter layer and a blocking material such as a photomask, thereby preventing external light from entering the element through the side wall and generating an erroneous signal, thereby improving the detection accuracy of the photodetector.

[0026] 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]

[0027] 1. Photodetector element 10 Substrate 12 Chamfered structure 20 Light receiving area 30 filter layers 40 Upper electrode 50 Lower electrode 60 photomask layers

Claims

1. A photodetector element, A substrate; a light receiving region disposed on the substrate; a filter layer covering the light receiving region, selectively transmitting only light of a specific wavelength, allowing the light to be received by the light receiving region, and blocking light of other wavelengths; A photodetector element in which a chamfered structure is formed on each of two side edges of the substrate, and the filter layer covers each of the chamfered structures on each of the side edges, blocking light of the other wavelengths from passing through the two side edges of the substrate and being received by the light receiving region.

2. 2. The photodetector according to claim 1, wherein the filter layer is a band pass filter layer.

3. The bandpass filter layer is made of tantalum pentoxide (Ta ２ O ５ ) and silicon dioxide (SiO ２ 3. The photodetector element according to claim 2, wherein the photodetector element is a composite layer of:

4. 2. The photodetector element according to claim 1, wherein the chamfered structure has a maximum depth measured from the top surface of the substrate that is less than one-quarter of the thickness of the substrate.

5. 5. The photodetector according to claim 4, wherein the chamfered structure has a depth of 40 [mu]m.

6. The photodetector according to claim 1 , further comprising a photomask layer covering a portion of the filter layer above the chamfered structure.

7. 7. The photodetector element according to claim 6, wherein the material of the photomask layer includes a color photoresist.

8. 7. The photodetector element according to claim 6, wherein the material of the photomask layer is one selected from the group consisting of aluminum, titanium, copper, silver, gold, and alloys thereof.

9. 2. The photodetector element according to claim 1, wherein the light of the specific wavelength is ultraviolet light in the wavelength range of 100 nm to 400 nm.

10. 2. The photodetector element of claim 1, wherein the light-receiving region includes a silicon diode photosensitive structure.

11. 2. The photodetector according to claim 1, wherein the substrate is a silicon substrate.

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