OPTICAL SENSING DEVICE

Abstract

A optical sensing device includes a substrate, an optical acting area and a filter layer. The optical acting area is disposed on the substrate. The filter layer covers the optical acting area and selectively allows only a light beam with a specific wavelength to pass through and be received by the optical acting area while blocking the light beams with other wavelengths. Each of the two sides of the substrate has a bevel structure. The filter layer covers each bevel structure of each side to prevent the light beams with other wavelengths from passing through the two sides of the substrate being received by the optical acting area.

Claims

1. An optical sensing device, comprising: a substrate; an optical acting area, disposed on the substrate; and a filter layer, covering the optical acting area and selectively allowing only a light beam with a specific wavelength to pass through and to be received by the optical acting area while blocking light beams with other wavelengths, wherein each of the two sides of the substrate has a bevel structure, the filter layer covers each of the bevel structure of the two sides to prevent the light beams with other wavelengths from passing through the two sides of the substrate being received by the optical acting area.

2. The optical sensing device of claim 1, wherein the filter layer is a band pass filter.

3. The optical sensing device of claim 2, wherein the band pass filter is a composite layer of Ta.sub.2O.sub.5 and SiO.sub.2.

4. The optical sensing device of claim 1, wherein the depth of the bevel structure is smaller than of the thickness of the substrate.

5. The optical sensing device of claim 4, wherein the depth of the bevel structure is approximately 40 m.

6. The optical sensing device of claim 1, further comprising a mask layer partially covering the filter layer on each of the bevel structure.

7. The optical sensing device of claim 6, wherein the material of the mask layer containing color photoresist.

8. The optical sensing device of claim 6, wherein the material of the mask layer is selected from a group consisting of aluminum, titanium, copper, silver, gold and an alloy combination thereof.

9. The optical sensing device of claim 1, wherein the light beam with the specific wavelength is the ultraviolet light beam with the wavelength ranging from about 100 nm to 400 nm.

10. The optical sensing device of claim 1, wherein the optical acting area comprises a silicon photodiode structure.

11. The optical sensing device of claim 1, wherein the substrate is a silicon substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The figure is a schematic structural diagram of an optical sensing device in an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] The content of the present invention will be explained through examples below. The examples of the present invention are not intended to limit the implementation of the present invention to any specific environment, application, or particular manner as described in the examples. Therefore, the description of the examples is only to elucidate the purpose of the present invention, and not to limit the present invention. It should be noted that in the following examples and the figure, components not directly related to the present invention have been omitted and not shown. The dimensional relationships between the components in the figure are provided for ease of understanding and are not intended to limit the actual proportions.

[0021] Please refer to the figure, which illustrates a schematic diagram of the structure of the optical sensing device in an exemplary embodiment of the present invention. As shown in the diagram, the optical sensing device 1 in this embodiment comprises a substrate 10, an optical acting area 20, a filter layer 30, an upper electrode 40, and a lower electrode 50. The substrate 10 serves as the supporting material in the bottom of the optical sensing device 1. Typically, the substrate is made of optically transparent materials to allow the passage of light. The material for the substrate 10 is often chosen to have good light transmittance, such as silicon, quartz, and the like. In the present embodiment of the invention, silicon is used as the material for substrate 10. The thickness of the substrate 10 can vary based on specific application needs and design requirements, typically ranging from several hundred micrometers (m) to several millimeters (mm). In this embodiment of the present invention, the thickness of the silicon substrate 10 is approximately 400 micrometers.

[0022] Continuing with the figure, the optical acting area 20 is disposed in the central region on the substrate 10, serving as the part for detecting light signals. It is typically a P/N photodiode structure designed to receive light beams with specific wavelengths. Specifically, the optical acting area 20 in the present invention includes a silicon photodiode structure. Next, the filter layer 30 is a bandpass filter layer covering the optical acting area 20. The filter layer 30 selectively allows only light beams with a specific wavelength to pass through and be received by the optical acting area 20 while blocking light beams with other wavelengths. In one embodiment of the present invention, the filter layer 30 only allows ultraviolet light in the wavelength range of approximately 100 nm to 400 nm to pass through and blocks light beams with other wavelengths, such as visible light and far-infrared light, to prevent them from being absorbed by the optical acting area 20. The filter layer 30 is a multi-layer thin-film structure. In this embodiment of the present invention, the filter layer 30 is a composite layer of tantalum pentoxide (Ta.sub.2O.sub.5) and silicon dioxide (SiO.sub.2). The upper electrode 40 is disposed within the filter layer 30, and the lower electrode 50 is disposed on the backside of the substrate 10. The electrodes are used to apply an electric field to control the optical characteristics of the filter layer 30. By changing the voltage and thus modifying the refractive index of the dielectric layer in the filter layer structure, the main wavelengths or bandwidths of the light beams to be filtered out by the filter can be adjusted.

[0023] A distinctive feature of the optical sensing device 1 in the present invention is to reduce interference from side light beams. To achieve this purpose, bevel structures 12 are respectively set on both sides of the substrate 10, as shown in the dashed area in the figure. In specific applications, these bevel structures 12 are formed on the substrate 10 through an isotropic etching process. The depth of the bevel structure 12 on the substrate 10 is typically less than of that of the substrate 10. Specifically, when the thickness of the substrate 10 is approximately 400 micrometers, the depth of the bevel structure 12 on the substrate ranges from 0 to 100 micrometers. In a preferred embodiment of the present invention, the depth of the bevel structure 12 on the substrate can be 40 micrometers.

[0024] Continuing with the figure, as shown in the diagram, the filter layer 30 covers the entire substrate 10 and the optical acting area 20. Therefore, the filter layer 30 also conformally covers each bevel structure 12 on both sides of the substrate 10. Due to the beveled contour of the bevel structures 12, the two sides of the filter layer 30 have a similar downward-sloping beveled profile compared to the central region. Consequently, the downward-sloping portions of the filter layer 30 effectively prevent external light beams, other than light beams with a specific wavelength, for example, external light beams except for ultraviolet light, from entering the interior through the sidewalls of the substrate. This prevents erroneous signals from being generated by light beams with wavelengths other than the specific wavelength, ensuring the accuracy of the detection in the optical acting area.

[0025] In order to further reduce interference from side light beams, the optical sensing device 1 of the present invention includes an additional mask layer 60 covering a portion of the filter layer 30 on each bevel structure 12. The material of the mask layer 60 may include color photoresist or metallic materials to further block external light interference on the sidewalls of the substrate. The color photoresist in the mask layer 60 can be materials such as, but not limited to, zinc sulfide (ZnS), cadmium selenide (CdSe). On the other hand, the metallic material in the mask layer 60 can be formed on a portion of the filter layer 30 on each bevel structure 12 through sputtering or physical vapor deposition. The metallic material can be selected from a group consisting of aluminum, titanium, copper, silver, gold, and the alloy combination thereof.

[0026] In summary, the optical sensing device of the present invention achieves enhances accuracy in light detection by forming bevel structures through etching at the edges of the device. The surface of the device is then covered with a filter layer and a mask layer serving as shielding materials to further block external light from entering the interior through the sidewalls of the device and causing erroneous signals.

[0027] The above embodiments are provided for illustrative purposes 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 modifications or equivalents that can be easily made by those skilled in the art are within the scope claimed by the present invention, and the scope of protection of the present invention shall be determined by the scope of the Patent Application.