Photodiode Structure

Abstract

To provide a photodiode structure capable of reducing radio frequency interference.SOLUTION: A semiconductor structure 20 is located on a first electrode 10. A first anti-reflective layer 30 is located on the semiconductor structure 20. A second anti-reflective layer 40 is located on the first anti-reflective layer 30. A second electrode 50 is located on the second anti-reflective layer 40 and electrically connected to the semiconductor structure 20 through the first anti-reflective layer 30 and the second anti-reflective layer 40. A blocking structure 60 is disposed between the first anti-reflective layer 30 and the second electrode 50 to prevent the first anti-reflective layer 30 from directly contacting the second electrode 50.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a photodiode, and more particularly to a photodiode structure capable of reducing radio frequency interference. [Background technology]

[0002] Photodiodes receive external light and output a corresponding analog signal or switch different states in a circuit. Currently, photodiodes are widely used in products that require optical measurement. For example, many smart wearable devices use photodiodes to perform functions such as measuring pulse and blood oxygen.

[0003] However, smart wearable devices often emit radio frequency (RF) signals when performing communication functions. These radio frequency signals easily enter the photodiode structure through the electrodes of the conventional photodiode during transmission, generating an offset voltage. For example, as shown in FIG. 1, the conventional photodiode structure 300 has a first anti-reflection layer 320 and a second anti-reflection layer 330 formed in sequence on a semiconductor structure 310. After forming a portion in the first anti-reflection layer 320 and the second anti-reflection layer 330 where the semiconductor structure 310 is exposed by an etching process, an electrode 340 is formed on the portion by a metallization process. A radio frequency interference test (radio frequency is about 800 MHz) was performed on the conventional photodiode structure 300 shown in FIG. 1, and the result is shown in FIG. 2. In FIG. 2, the test results at the top position of the wafer are shown by the broken line "Top", the test results at the center position of the wafer are shown by the broken line "Center", the test results at the bottom position of the wafer are shown by the broken line "Bottom", the test results at the left position of the wafer are shown by the broken line "Left", and the test results at the right position of the wafer are shown by the broken line "Right". It can be seen that the radio frequency interference RFI starts to decrease significantly and a voltage offset occurs when the radio frequency root mean square voltage RF Vrms increases to about 1V because the first anti-reflection layer 320 is in direct contact with the electrode 340. It can be seen that the conventional photodiode structure 300 is affected by radio frequency interference, resulting in a decrease in detection accuracy and performance.

[0004] Therefore, how to improve the above problems and design a photodiode structure that can reduce radio frequency interference is a topic worthy of research. Summary of the Invention

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a photodiode structure capable of reducing radio frequency interference.

[0006] In order to achieve the above object, the photodiode structure of the present invention includes a first electrode, a semiconductor structure, a first anti-reflection layer, a second anti-reflection layer, a second electrode, and a blocking structure. The semiconductor structure is located on the first electrode. The first anti-reflection layer is located on the semiconductor structure. The second anti-reflection layer is located on the first anti-reflection layer. The second electrode is located on the second anti-reflection layer and electrically connected to the semiconductor structure through the first anti-reflection layer and the second anti-reflection layer. The blocking structure is disposed between the first anti-reflection layer and the second electrode to prevent the first anti-reflection layer from directly contacting the second electrode.

[0007] In an embodiment of the present invention, the first anti-reflection layer is formed with a first hollow portion for exposing a portion of the semiconductor structure, and the blocking structure is located within the first hollow portion.

[0008] In an embodiment of the present invention, the second anti-reflection layer has a second hollow portion formed at a position corresponding to the position of the first hollow portion.

[0009] In an embodiment of the present invention, the blocking structure is formed with a through hole for exposing a part of the semiconductor structure, and the radial length of the through hole is not greater than the radial length of the second hollow portion.

[0010] In an embodiment of the present invention, the blocking structure and the second anti-reflection layer are made of the same material.

[0011] In an embodiment of the present invention, the blocking structure is connected to the second anti-reflection layer.

[0012] In an embodiment of the present invention, the first anti-reflective layer is made of silicon nitride.

[0013] In an embodiment of the present invention, the thickness of the first anti-reflection layer is from 10 nm to 50 nm.

[0014] In an embodiment of the present invention, the second anti-reflective layer comprises niobium pentoxide and silicon dioxide.

[0015] In an embodiment of the present invention, the thickness of the second anti-reflection layer is from 100 nm to 150 nm.

[0016] As a result, the photodiode structure of the present invention can effectively improve the problem of radio frequency interference by installing a blocking structure, so that when the photodiode structure of the present invention is applied to a smart wearable device, it can improve detection accuracy and performance without being affected by radio frequency signals. [Brief description of the drawings]

[0017] [Figure 1] Schematic diagram showing the structure of a conventional photodiode [Diagram 2] Figure showing the results of radio frequency interference testing using a conventional photodiode [Diagram 3] Schematic diagram showing the structure of a photodiode according to the present invention. [Figure 4A] FIG. 1 is a partial schematic diagram showing a structure of a photodiode before a second electrode according to the present invention is formed; [Figure 4B] FIG. 1 is a partial schematic diagram showing the structure of a photodiode after a second electrode according to the present invention is formed; [Diagram 5] FIG. 1 shows the results of a radio frequency interference test on a photodiode structure according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Each aspect and embodiment is merely illustrative and not limiting, so that after reading this specification, a person of ordinary skill in the art may make other aspects and embodiments without departing from the scope of the present invention. The features and advantages of these embodiments will become more apparent according to the following detailed description and the scope of the patent application.

[0019] The terms "a" or "one" are used herein to describe elements and components described herein. This is for convenience and to give a general sense of the scope of the invention. Thus, unless otherwise indicated, such descriptions are understood to include one or at least one, and the singular also includes the plural.

[0020] In this specification, the ordinal terms "first" and "second" are primarily used to distinguish or refer to identical or similar components or structures, and do not necessarily imply a spatial or temporal ordering of these components or structures. It should be noted that in certain situations or configurations, the ordinal terms may be used interchangeably without affecting the practice of the present invention.

[0021] As used herein, the terms "comprise," "have," or other similar terms are intended to be non-exclusive inclusive, e.g., a component or structure comprising multiple elements is not limited to only the elements listed herein, but may include other elements that are not expressly listed, but are inherent to the component or structure.

[0022] The following description will be made with reference to FIG. 3 to FIG. 4B. FIG. 3 is a schematic diagram showing the structure of a photodiode according to the present invention. FIG. 4A is a partial schematic diagram showing the structure of a photodiode before the second electrode according to the present invention is formed. FIG. 4B is a partial schematic diagram showing the structure of a photodiode after the second electrode according to the present invention is formed. As shown in FIG. 3 to FIG. 4B, the photodiode structure 1 according to the present invention includes a first electrode 10, a semiconductor structure 20, a first anti-reflection layer 30, a second anti-reflection layer 40, a second electrode 50, and a blocking structure 60. The first electrode 10 is disposed on one surface of the semiconductor structure 20. The first electrode 10 is formed by performing a metallization process on the aforementioned surface. In the present invention, the first electrode 10 is a negative electrode, but the present invention is not limited thereto.

[0023] The semiconductor structure 20 is located on the first electrode 10. The semiconductor structure 20 is a base structure of the photodiode structure 1 according to the present invention. The semiconductor structure 20 can be roughly divided into a first semiconductor layer 21 and a second semiconductor layer 22. The first semiconductor layer 21 is mainly made of an N-type semiconductor material. The second semiconductor layer 22 is mainly made of a P-type semiconductor material. A PN junction is formed between the first semiconductor layer 21 and the second semiconductor layer 22. The first semiconductor layer 21 of the semiconductor structure 20 is connected to the first electrode 10.

[0024] The first anti-reflective layer 30 is located on the semiconductor structure 20 and covers most of the surface of the semiconductor structure 20. In an embodiment of the present invention, the first anti-reflective layer 30 is formed from silicon nitride (SiNx) by a low-pressure chemical vapor deposition (LPCVD) process. The thickness of the first anti-reflective layer 30 is 10 nm to 50 nm. However, the material and / or thickness of the first anti-reflective layer 30 may vary according to design requirements. A first hollow portion 31 is formed in the first anti-reflective layer 30. A part of the semiconductor structure 20 is exposed by the first hollow portion 31.

[0025] The second anti-reflective layer 40 is located on the first anti-reflective layer 30 and covers most of the surface of the first anti-reflective layer 30. In an embodiment of the present invention, the second anti-reflective layer 40 is formed of niobium pentoxide (Nb 2 O 5 ) and silicon dioxide (SiO 2). The thickness of the second anti-reflection layer 40 is 100 nm to 150 nm. However, the material and / or thickness of the second anti-reflection layer 40 may vary depending on design requirements. A second hollow portion 41 is formed in the second anti-reflection layer 40. The position of the second hollow portion 41 corresponds to the position of the first hollow portion 31. In the present invention, the second hollow portion 41 is located approximately directly above the first hollow portion 31, and the radial length of the second hollow portion 41 is not smaller than the radial length of the first hollow portion 31. For example, when the first hollow portion 31 and the second hollow portion 41 are both cylindrical holes, the radial length is the diameter of the corresponding cylindrical hole.

[0026] The second electrode 50 is located on the second anti-reflection layer 40, and is electrically connected to the semiconductor structure 20 through the first anti-reflection layer 30 and the second anti-reflection layer 40. In detail, the second electrode 50 passes through the second hollow portion 41 of the second anti-reflection layer 40 and the first hollow portion 31 of the first anti-reflection layer 30 in order along a direction perpendicular to the surface of the first anti-reflection layer 30 and the surface of the second anti-reflection layer 40, and contacts the semiconductor structure 20 exposed in the first hollow portion 31. Thereby, the second electrode 50 forms an ohmic contact with the semiconductor structure 20. In the present invention, the second electrode 50 is a positive electrode, but the present invention is not limited thereto.

[0027] The blocking structure 60 is disposed between the first anti-reflection layer 30 and the second electrode 50, and prevents the first anti-reflection layer 30 from directly contacting the second electrode 50. In detail, the blocking structure 60 is located in the first hollow portion 31 of the first anti-reflection layer 30. The thickness of the blocking structure 60 is the same as that of the first anti-reflection layer 30. In the present invention, the blocking structure 60 is formed with a through-portion 61 for exposing a part of the semiconductor structure 20 that was exposed in the first hollow portion 31. In the structure design, the radial length of the through-portion 61 of the blocking structure 60 is not greater than the radial length of the second hollow portion 41 of the second anti-reflection layer 40. For example, when the through-portion 61 is a cylindrical hole, the radial length is the diameter of the corresponding cylindrical hole.

[0028] In the embodiment of the present invention, the blocking structure 60 and the second anti-reflection layer 40 are made of the same material. For example, after coating the first anti-reflection layer 30 on the surface of the semiconductor structure 20 and forming the first hollow portion 31, the second anti-reflection layer 40 and the blocking structure 60 can be simultaneously formed of the same material by a PVD coating process. Then, the through portion 61 of the blocking structure 60 and the second hollow portion 41 of the second anti-reflection layer 40 are formed by a photo-etching process. Note that, in the embodiment of the present invention, the blocking structure 60 is connected to the second anti-reflection layer 40 by the same PVD coating process.

[0029] 1 and 2. As shown in FIG. 1 and FIG. 2, for the conventional photodiode structure 300, the first anti-reflection layer 320 is in direct contact with the electrode 340, so there is no similar structure design to the blocking structure of the present invention. From the results of radio frequency interference test (radio frequency is about 800MHz), it can be seen that when the radio frequency root mean square voltage RF Vrms increases to about 1V, the radio frequency interference RFI begins to decrease significantly and a voltage offset occurs. Therefore, as the radio frequency signal becomes stronger, the conventional photodiode structure 300 becomes more susceptible to radio frequency interference.

[0030] The following description will be made with reference to FIG. 3 and FIG. 5. FIG. 5 is a diagram showing the results of radio frequency interference testing on the photodiode structure according to the present invention. In FIG. 5, the test results at the top position of the wafer are shown by the broken line "Top", the test results at the center position of the wafer are shown by the broken line "Center", the test results at the bottom position of the wafer are shown by the broken line "Bottom", the test results at the left position of the wafer are shown by the broken line "Left", and the test results at the right position of the wafer are shown by the broken line "Right". As shown in FIG. 3 and FIG. 5, for the photodiode structure 1 according to the present invention, the blocking structure 60 prevents the first anti-reflection layer 30 from directly contacting the second electrode 50. The results of radio frequency interference testing (radio frequency is about 800 MHz) at different positions under the same conditions are the same. It can be seen from the results that even if the radio frequency root mean square voltage RF Vrms increases to about 1.3 V, the radio frequency interference RFI is stable and no voltage offset occurs. Therefore, the photodiode structure 1 according to the present invention is less susceptible to radio frequency interference and has the advantage over conventional photodiode structures.

[0031] The above-described embodiments are merely illustrative and are not intended to limit the embodiments of the present application or their applications. Furthermore, while at least one illustrative example has been shown in the above-described embodiments, it should be understood that many variations of the present invention may exist. Furthermore, the examples described herein are not intended to limit the scope, application, or configuration of the claims in any manner. Rather, the above-described embodiments provide a guide for those of ordinary skill in the art to implement one or more of the embodiments. Furthermore, changes may be made in the function and arrangement of elements without departing from the scope of the claims, which include all known and foreseeable equivalents at the time of filing of this patent application. [Explanation of symbols]

[0032] 1. Photodiode structure 10 1st electrode 20 Semiconductor Structure 21 First semiconductor layer 22 Second semiconductor layer 30 1st anti-reflection layer 31 1st hollow part 40 Second anti-reflection layer 41 2nd hollow part 50 2nd electrode 60 Blocking Structure 61 Penetration 300 Photodiode Structure 310 Semiconductor Structure 320 1st anti-reflection layer 330 Second anti-reflection layer 340 electrode

Claims

1. A photodiode structure comprising: A first electrode; a semiconductor structure located on the first electrode; a first antireflective layer overlying the semiconductor structure; a second anti-reflective layer located on the first anti-reflective layer; a second electrode located on the second anti-reflective layer, passing through the first anti-reflective layer and the second anti-reflective layer, and electrically connected to the semiconductor structure; a blocking structure disposed between the first anti-reflection layer and the second electrode, the blocking structure preventing the first anti-reflection layer from directly contacting the second electrode.

2. 2. The photodiode structure of claim 1, wherein the first anti-reflection layer has a first hollow portion formed therein for exposing a portion of the semiconductor structure, and the blocking structure is located within the first hollow portion.

3. 3. The photodiode structure according to claim 2, wherein the second antireflection layer has a second hollow portion formed at a position corresponding to a position of the first hollow portion.

4. 4. The photodiode structure of claim 3, wherein the blocking structure has a through-portion for exposing a portion of the semiconductor structure, and the radial length of the through-portion is not greater than the radial length of the second hollow portion.

5. 2. The photodiode structure of claim 1, wherein the blocking structure and the second anti-reflection layer are made of the same material.

6. The photodiode structure of claim 5 , wherein the blocking structure is connected to the second anti-reflection layer.

7. 2. The photodiode structure of claim 1, wherein the first anti-reflection layer is made of silicon nitride.

8. 2. The photodiode structure of claim 1, wherein the first anti-reflection layer has a thickness of 10 nm to 50 nm.

9. 2. The photodiode structure of claim 1, wherein the second anti-reflection layer is made of niobium pentoxide and silicon dioxide.

10. 2. The photodiode structure of claim 1, wherein the second anti-reflection layer has a thickness of 100 nm to 150 nm.

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