Light sensing element

Abstract

The invention relates to a light sensing element. The light sensing element comprises a substrate, a light action area and a filtering layer, wherein the light action area is arranged on the substrate, the filtering layer covers the light action area, only light with a specific wavelength is selectively allowed to pass through and is received by the light action area, and light with other wavelengths is blocked from passing through. The two side edges of the substrate are respectively provided with an oblique angle structure, the filtering layer covers the oblique angle structures of the side edges, and light rays with other wavelengths are prevented from penetrating through the two side edges of the substrate and being received by the light action area.

Description

Technical Field

[0001] The invention relates to a light sensing element, and in particular to a light sensing element with a side bevel structure. Background Art

[0002] A bandpass filter (BPF) is an optical component that selectively allows light of a specific wavelength range to pass through while filtering out light of other wavelengths. This filter is very useful in optical sensing devices because it can be used to separate and detect specific wavelengths or frequencies of light in a certain area, and is therefore used in technical fields such as biomedical imaging and environmental monitoring.

[0003] The working principle of optical bandpass filters is based on the interference and reflection of light. They usually consist of a transparent substrate and a multilayer thin film structure. These thin film layers are alternately stacked in different materials and have specific optical thicknesses to achieve high transmittance for specific wavelengths and high reflectivity for other wavelengths. When light hits the surface of the filter, it enters the multilayer thin film structure of the filter, and the light interferes and reflects at the material interface between the multilayer thin film structures. Since different wavelengths of light propagate at different speeds in different materials, the interference between the multilayer thin film structures will cause some wavelengths of light to be phase-added and enhanced, while other wavelengths of light will be phase-destructed and weakened. Through proper design, the multilayer thin film structure of the filter can form a resonant cavity, so that light of specific wavelengths can be enhanced, while other wavelengths of light will be reflected or absorbed, allowing light beams of specific wavelengths to pass through the filter, forming the so-called "bandpass" effect.

[0004] However, although conventional sensing devices can use bandpass filters to filter specific light wavelengths, in actual applications, some light still enters the sensing device and generates photocurrent on the photodiode interface, affecting detection accuracy. To overcome the above problems, the industry urgently needs an innovative light sensing structure to improve the above filtering problem. Summary of the invention

[0005] The main purpose of the present invention is to provide an innovative light sensing element to improve the existing problems of erroneous signals caused by poor filtering and reduced sensing accuracy.

[0006] To achieve the above-mentioned purpose, the present invention provides a light sensing element, comprising a substrate, a light action area and a filter layer. The light action area is arranged on the substrate, and the filter layer covers the light action area, selectively allowing only a light of a specific wavelength to pass through and be received by the light action area, while blocking the light of other wavelengths from passing through. Both sides of the substrate have an angled structure, and the filter layer covers each angled structure of each side, blocking the light of other wavelengths from passing through the two sides of the substrate and being received by the light action area.

[0007] In one embodiment, the light sensing element provided by the present invention, wherein the filter layer is a bandpass filter layer.

[0008] In one embodiment, the present invention provides a light sensing element, wherein the bandpass filter layer is a composite layer of tantalum pentoxide (Ta2O5) and silicon dioxide (SiO2).

[0009] In one embodiment, the present invention provides a light sensing device, wherein the depth of the oblique angle structure is less than approximately 1 / 4 of the thickness of the substrate.

[0010] In one embodiment, the present invention provides a light sensing device, wherein the depth of the bevel structure is about 40 μm.

[0011] In one embodiment, the light sensing element provided by the present invention further comprises a mask layer, wherein the mask layer covers a portion of the filter layer on each of the oblique structures.

[0012] In one embodiment, the present invention provides a light sensing device, wherein the material of the mask layer includes a colored photoresist.

[0013] In one embodiment, the present invention provides a light sensing element, wherein the material of the mask layer is selected from the group consisting of aluminum, titanium, copper, silver, gold and alloys thereof.

[0014] In one embodiment, the light sensing element provided by the present invention allows only light of a specific wavelength to pass through and is received by the light action area. The specific wavelength of light is ultraviolet light, and its wavelength range is about 100nm to 400nm.

[0015] In one embodiment, the present invention provides a light sensing element, wherein the light active region comprises a silicon diode photosensitive structure.

[0016] In one embodiment, the present invention provides a light sensing device, wherein the substrate is a silicon substrate.

[0017] After referring to the accompanying drawings and the embodiments described below, a person skilled in the art will be able to understand other objects, technical means and implementation schemes of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 FIG. 4 is a schematic diagram of the structure of a light sensing element in an embodiment of the present invention.

[0019] Description of Reference Numerals

[0020] 1 Light sensor

[0021] 10 substrate

[0022] 12 Bevel structure

[0023] 20 Light action area

[0024] 30 filter layer

[0025] 40 Upper electrode

[0026] 50 Lower electrode

[0027] 60 Photomask layer. DETAILED DESCRIPTION

[0028] The present invention will be explained below by way of examples, and the examples of the present invention are not intended to limit the present invention to any specific environment, application or special method as described in the examples. Therefore, the description of the examples is only for the purpose of explaining the present invention, and is not intended to limit the present invention. It should be noted that in the following examples and drawings, elements that are not directly related to the present invention have been omitted and are not shown, and the dimensional relationship between the elements in the drawings is only for easy understanding, and is not intended to limit the actual proportion.

[0029] See also Figure 1 , which is a schematic diagram of the structure of a light sensing element in an embodiment of the present invention. As shown in the figure, the light sensing element 1 in this embodiment includes a substrate 10, a light active area 20, a filter layer 30, an upper electrode 40 and a lower electrode 50. Among them, the substrate 10 serves as the bottom supporting material of the light sensing element 1, and is usually made of an optically transparent material to allow light to pass through. The material of the substrate 10 is usually selected from materials with good light transmittance, such as silicon, quartz, etc. In the embodiment of the present invention, silicon is used as the material of the substrate 10. As for the thickness of the substrate 10, it can vary according to specific application needs and design requirements, usually in the range of hundreds of microns (μm) to several millimeters (mm). In the embodiment of the present invention, the thickness of the silicon substrate 10 is about 400 microns.

[0030] Please continue reading Figure 1, the light action area 20 is arranged in the central area of ​​the substrate 10, as a part for detecting light signals, and is usually a P / N diode photosensitive structure for receiving light of a specific wavelength. Specifically, the light action area 20 of the present invention comprises a silicon diode photosensitive structure. Secondly, the filter layer 30 is a band pass filter layer and covers the light action area 20, selectively allowing only light of a specific wavelength to pass through and be received by the light action area 20, and blocking light of other wavelengths from passing through. In one embodiment of the present invention, the filter layer 30 of the present invention only allows ultraviolet light of a specific wavelength in the range of about 100nm to 400nm to pass through, and blocks light of other wavelengths, such as visible light and far infrared light, which will be blocked from being absorbed by the light action area 20. The filter layer 30 is a multilayer thin 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 in the filter layer 30, and the lower electrode 50 is disposed on the back side of the substrate 10, for applying an electric field to control the optical properties of the filter layer 30. By changing the refractive index of the dielectric layer in the filter layer structure by voltage, the central wavelength or bandwidth of the filter can be adjusted.

[0031] A feature of the light sensing element 1 of the present invention is that an angled structure 12 is disposed on both sides of the substrate 10 to reduce interference in light measurement. Figure 1 The area indicated by the dotted line. In a specific application, the bevel structure 12 is formed by isotropic etching on the substrate 10 using a wet etching process, and the depth of the bevel structure 12 on the substrate 10 is approximately less than 1 / 4 of the thickness of the substrate 10. Specifically, when the thickness of the substrate 10 is approximately 400 microns, the depth of the bevel structure 12 on the substrate is between 0 and 100 microns. In a preferred embodiment of the present invention, the depth of the bevel structure 12 on the substrate can be 40 microns.

[0032] Please continue reading Figure 1 As shown in the figure, the filter layer 30 covers the entire substrate 10 and the light action area 20. Therefore, the filter layer 30 also conformally covers the bevel structures 12 on the sides of the substrate 10. Due to the bevel profile of the bevel structure 12, the two sides of the filter layer 30 also have the same bevel profile that is tilted downward to the side compared to the central area. Therefore, the downwardly tilted parts on both sides of the filter layer 30 can effectively prevent the light of other wavelengths except for the specific wavelengths of external light, such as ultraviolet light, from entering the interior through the side wall of the substrate and then being received by the light action area to generate an erroneous signal.

[0033] In order to further reduce the interference of light measurement, the light sensing element 1 of the present invention further sets a mask layer 60 in the light sensing element 1 to cover the part of the filter layer 30 on each bevel structure 12. The material of the mask layer 60 may include a colored photoresist or a metal material to further block the interference of external light on the side wall of the substrate. The colored photoresist of the mask layer 60 may be zinc sulfide (ZnS), cadmium selenide (CdSe), etc., but is not limited thereto. On the other hand, the metal material of the mask layer 60 may be formed on the part of the filter layer 30 on each bevel structure 12 by sputtering or physical vapor deposition, and the metal material may be selected from one of the group consisting of aluminum, titanium, copper, silver, gold and their alloys.

[0034] In summary, the optical sensing element of the present invention forms an angled structure by etching the edge of the element, and covers its surface with a filter layer and masking materials such as a mask to further block external light from entering the interior through the side wall of the element to cause erroneous signals, thereby improving the detection accuracy of the optical sensing element.

[0035] The above embodiments are only used to illustrate the embodiments of the present invention and to explain the technical features of the present invention, and are not used to limit the protection scope of the present invention. Any changes or equivalent arrangements that can be easily completed by those skilled in the art belong to the scope claimed by the present invention, and the scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A light sensing element, comprising: a substrate; a light action area disposed on the substrate; a filter layer covering the light action area, selectively allowing only light of a specific wavelength to pass through and be received by the light action area, while blocking light of other wavelengths from passing through, in, Both sides of the substrate have an oblique angle structure, and the filter layer covers the oblique angle structures of the sides to block the light of other wavelengths from passing through the two sides of the substrate and being received by the light action area. 2 . The light sensing element as claimed in claim 1 , wherein the filter layer is a bandpass filter layer. 3 . The optical sensor device as claimed in claim 2 , wherein the bandpass filter layer is a composite layer of tantalum pentoxide and silicon dioxide. 4 . The light sensing device as claimed in claim 1 , wherein a depth of the angled structure is approximately less than ¼ of a thickness of the substrate. The light sensing device as claimed in claim 4 , wherein a depth of the bevel structure is about 40 μm. 6 . The light sensing device as claimed in claim 1 , further comprising a mask layer, wherein the mask layer covers a portion of the filter layer on each of the angled structures. 7 . The light sensing device as claimed in claim 6 , wherein a material of the mask layer comprises a colored photoresist. 8 . The light sensing element as claimed in claim 6 , wherein a material of the mask layer is selected from the group consisting of aluminum, titanium, copper, silver, gold and alloys thereof. 9 . The light sensing device as claimed in claim 1 , wherein the wavelength of the ultraviolet light of the specific wavelength ranges from about 100 nm to 400 nm.

10. The light sensing device as claimed in claim 1, wherein the light active region comprises a silicon diode photosensitive structure. The light sensing device as claimed in claim 1 , wherein the substrate is a silicon substrate.

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