Photodiode and method for manufacturing the same

Abstract

The present invention provides a photodiode and a method for manufacturing the same that can effectively reduce the concentration of external light after it enters the element, thereby improving the response linearity of the photodiode and reducing problems such as erroneous signals resulting from insufficient linearity. [Solution] The device includes a first conductivity semiconductor layer 110, an intrinsic layer 120 placed on the first conductivity semiconductor layer 110 which generates a photocurrent after absorbing light of a specific wavelength, a second conductivity semiconductor layer 130 placed on the central region of the intrinsic layer 120 which exposes the peripheral region of the intrinsic layer 120 surrounding the central region, and a metal silicide layer 150 placed on the edge of the peripheral region of the intrinsic layer 120, wherein the metal silicide layer 150 reduces the amount of light that passes through the edge and enters the intrinsic layer 120 and is absorbed by the intrinsic layer 120.

Description

[Technical Field]

[0001] The present invention relates to a photodiode and a method for manufacturing the same, and more particularly to a photodiode with high response linearity and a method for manufacturing the same. [Background technology]

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

[0003] A photodiode absorbs external light using its internal semiconductor material (e.g., a silicon substrate). When a photon enters and is absorbed by the photodiode, its energy causes electrons in the valence band to transition to the conduction band, generating electron-hole pairs. The electric field inside the diode separates these photogenerated carriers, generating an electric current.

[0004] However, conventional photodiodes have the following problems in practical applications: External light easily enters the device through the sidewall, interfering with internal operation and further negatively affecting the response linearity of the photosensor and subsequent calculations in the device's application. As shown in Figure 1, after external light passes through the exposed sidewall of a conventional photodiode, the light concentrates at the edge of the device because the refractive index of the silicon substrate (3.4) is greater than that of air (1), thus negatively affecting the response linearity of the photodiode.

[0005] As shown in Figure 2, line segment I1 represents the linearity of the photodiode in its ideal state. There is a linear relationship between the increase in the incident power of the external light and the current intensity generated by the photodiode. Line segment I2 represents the linearity of the current intensity generated in response to the incident power of the external light when the photodiode is actually operating. As is clearly visible from the figure, as the incident power increases, the electrical signal intensity generated by the photodiode cannot maintain a linear increase relationship and some degree of attenuation occurs. Furthermore, as shown in Figure 3, when analyzing the response linearity at various locations on the photodiode body, it can be seen that the response linearity remains consistent in the central region of the photodiode, but decreases sharply in the edge region of the element. To overcome the above problems, the industry needs innovative photodiodes that improve the lack of response linearity that occurs after the external light passes through the sidewall of the element. [Overview of the Initiative]

[0006] The main objective of the present invention is to provide an innovative photodiode and a method for manufacturing the same. Compared with conventional photoelectric elements, the photodiode of the present invention has a metal silicide layer on the upper edge of the element. This design effectively reduces the concentration of external light after it enters the element. Such improvements not only enhance the response linearity of the photodiode but also reduce problems such as erroneous signals resulting from insufficient linearity.

[0007] To achieve the above objective, the present invention provides a photodiode comprising a first conductivity type semiconductor layer, an intrinsic layer, a second conductivity type semiconductor layer, and a metal silicide layer. The intrinsic layer is placed on the first conductivity type semiconductor layer and generates a photocurrent after absorbing light of a specific wavelength. The second conductivity type semiconductor layer is placed on the central region of the intrinsic layer, exposing the peripheral region of the intrinsic layer surrounding the central region. The metal silicide layer is placed on the edge of the peripheral region of the intrinsic layer. The metal silicide layer reduces the amount of light that passes through the edge and enters the intrinsic layer and is absorbed by the intrinsic layer.

[0008] In the photodiode of the embodiment of the present invention, the metal of the metal silicide layer is selected from the group consisting of nickel (Ni), platinum (Pt), gold (Au), cobalt (Co), chromium (Cr), vanadium (V), titanium (Ti), and tungsten (W).

[0009] In the photodiode of the embodiment of the present invention, the depth of the metal silicide layer is 1 micrometer (μm) or less.

[0010] In the photodiode of the embodiment of the present invention, the width of the metal silicide layer is substantially equal to half the width of the peripheral region of the intrinsic layer.

[0011] In the photodiode of the embodiment of the present invention, the thickness of the intrinsic layer is approximately 50 to 70 micrometers (μm).

[0012] In the photodiode of the embodiment of the present invention, the intrinsic layer is an N-type lightly doped silicon layer, the dopant is phosphorus (P), and the doping concentration is 10 12~13 cm -3 That is the case.

[0013] To achieve the above objective, the present invention provides a method for manufacturing a photodiode. The method for manufacturing a photodiode includes the steps of: forming a first conductivity type semiconductor layer; forming an intrinsic layer placed on the first conductivity type semiconductor layer and generating a photocurrent after absorbing light of a specific wavelength; forming a second conductivity type semiconductor layer placed on the central region of the intrinsic layer and exposing the peripheral region of the intrinsic layer surrounding the central region; and forming a metal silicide layer on the edge of the peripheral region of the intrinsic layer. The metal silicide layer can reduce the amount of light that passes through the edge and enters the intrinsic layer and is absorbed by the intrinsic layer.

[0014] In the manufacturing method of the embodiment of the present invention, the step of forming a metal silicide layer is a step of performing metal ion implantation and diffusion.

[0015] In the manufacturing method of the embodiment of the present invention, the metal used for metal ion implantation and diffusion is one selected from the group consisting of nickel (Ni), platinum (Pt), gold (Au), cobalt (Co), chromium (Cr), vanadium (V), titanium (Ti), and tungsten (W).

[0016] In the manufacturing method of the embodiment of the present invention, the step of forming a metal silicide layer is the step of forming a nickel silicide layer with a depth of 1 micrometer (μm) or less.

[0017] In the manufacturing method of the embodiment of the present invention, the step of forming a metal silicide layer is the step of forming a nickel silicide layer whose width is substantially equal to half the width of the peripheral region of the intrinsic layer.

[0018] In the manufacturing method of the embodiment of the present invention, the step of forming an intrinsic layer is to form a layer with a thickness of about 50 to 70 micrometers (μm), a dopant of phosphorus (P), and a doping concentration of 10 12~13 cm -3 This is the step of forming an N-type light-doped silicon layer.

[0019] Those skilled in the art will be able to 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 later. [Brief explanation of the drawing]

[0020] [Figure 1] Schematic diagram of light focusing after external light is incident on a conventional photodiode structure. [Figure 2] Schematic diagram of the response linearity of a conventional photodiode in its ideal state and during actual operation. [Figure 3] Schematic diagram of response linearity at various positions inside a conventional photodiode. [Figure 4] Schematic diagram of a photodiode according to an embodiment of the present invention. [Figure 5] Schematic diagram of the manufacturing process of a photodiode according to an embodiment of the present invention. [Modes for carrying out the invention]

[0021] Hereinafter, the content of the present invention will be described through examples. Note that the examples of the present invention show examples of embodiments, and are not intended to be limited to the environments, applications, or specific aspects as described in the examples. Therefore, the description of the examples is for explaining the present invention, but does not limit the present invention. In the embodiments and the drawings, components not directly related to the present invention are omitted and not shown. The dimensional relationships of the components in the drawings are for facilitating understanding and do not limit the actual dimensions.

[0022] FIG. 4 is a schematic diagram of a photodiode according to an embodiment of the present invention. In this embodiment, the photodiode 100 includes a first conductivity type semiconductor layer 110, an intrinsic layer 120, a second conductivity type semiconductor layer 130, a protective layer 140, a metal silicide layer 150, an upper electrode 160, and a lower electrode 170. The first conductivity type semiconductor layer 110 is an N-type highly doped semiconductor layer, for example, a silicon wafer doped with antimony (Sb), but is not limited thereto. The doping concentration is about 10 18~19 cm -3 , and the thickness is about 70 to 80 micrometers (μm), but is not limited thereto. The intrinsic layer 120 is a lightly doped semiconductor layer grown on the first conductivity type semiconductor layer 110 by epitaxial growth. The intrinsic layer 120 is, for example, an N-type lightly doped silicon layer, the dopant is phosphorus (P), and the doping concentration is 10 12~13 cm -3 , but is not limited thereto. The intrinsic layer 120 generates a photocurrent after absorbing light of a specific wavelength. The thickness of the intrinsic layer 120 is usually accurately designed based on the wavelength of light and application needs. The control of the thickness of the intrinsic layer 120 is important for the photoelectric conversion efficiency. In the example of the present invention, the thickness of the intrinsic layer 120 is about 50 to 70 micrometers (μm), but is not limited thereto.

[0023] Also, as shown in FIG. 4, the second-conductivity-type semiconductor layer 130 is disposed on the central region of the intrinsic layer 120. The peripheral region of the intrinsic layer 120 surrounding the central region is exposed. The second-conductivity-type semiconductor layer 130 is a P-type doped semiconductor layer, for example, a silicon layer with dopant boron (B), but is not limited thereto. The doping concentration is 10 19~20 cm -3 . The protective layer 140 is usually a band pass filter layer covering the second-conductivity-type semiconductor layer 130. The protective layer 140 selectively allows only light of a specific wavelength to pass through, so that it is received by the intrinsic layer 120, and blocks the passage of light of other wavelengths. For example, it blocks visible light and infrared light. The protective layer 140 is usually formed by laminating a plurality of dielectric materials. Usually, it has a structure in which materials with high refractive index and low refractive index are laminated alternately. The materials are, for example, silicon oxide (SiO2), titanium oxide (TiO2), or silicon nitride (Si3N4). In a more preferred embodiment, the protective layer 140 further includes an antireflection layer formed on the band pass filter layer. The antireflection layer can increase the transmittance of light in a specific band, improve the utilization rate of photons, minimize the reflection loss of incident light, and improve the photoelectric conversion efficiency of the device. Note that the upper electrode 160 is an anode electrode, which is disposed on the second-conductivity-type semiconductor layer 130 and is electrically connected thereto. The lower electrode 170 is a cathode electrode, which is disposed on the back side of the first-conductivity-type semiconductor layer 110 and is electrically connected thereto. The upper electrode 160 and the lower electrode 170 are made of aluminum, but are not limited thereto.

[0024] To overcome the problem of poor response linearity in conventional photodiodes, the photodiode 100 of the present invention has a metal silicide layer 150 placed on the upper edge of the structural body. This will be explained with reference to Figure 4. Specifically, the metal silicide layer 150 is placed on the edge of the peripheral region of the intrinsic layer 120. Specifically, the metal silicide layer 150 is formed by a conventional silicide manufacturing process. For example, after the formation of the second conductivity type semiconductor layer 130, a metal ion implantation and high-temperature diffusion process is performed on the surface of the edge of the peripheral region of the intrinsic layer 120. The metal used for metal ion implantation and diffusion is selected from the group consisting of nickel (Ni), platinum (Pt), gold (Au), cobalt (Co), chromium (Cr), vanadium (V), titanium (Ti), and tungsten (W). A thin metal silicide layer 150 is formed at the edge of the peripheral region of the intrinsic layer 120, with a depth of less than 1 micrometer (μm) from the upper surface of the intrinsic layer 120 and a width substantially equal to half the width of the peripheral region of the intrinsic layer 120. In more preferred embodiments, the metal silicide layer 150 is a nickel silicide layer, a platinum silicide layer, a cobalt silicide layer, and the like.

[0025] The purpose of placing a metal silicide layer on the photodiode of the present invention is to prevent the generation of an unexpected photocurrent, which occurs when some light is absorbed by the intrinsic layer after external light enters the device through the edge and sidewall of the intrinsic layer, thus avoiding adverse effects on the device's response linearity. Compared with conventional photodiodes, the metal silicide layer 150 of the photodiode 100 of the present invention effectively blocks some of the external light passing through the edge, thereby reducing the problem of external light concentration at the edge. The present invention can improve the response linearity at the edge of the photodiode and overcome the problem of insufficient response linearity at the edge of the device, as shown in Figure 3.

[0026] Figure 5 is a schematic diagram of the manufacturing process of the photodiode of the present invention. First, in step S01, a first conductivity type semiconductor layer is formed. Next, in step S02, an intrinsic layer is formed on the first conductivity type semiconductor layer. The intrinsic layer generates a photocurrent after absorbing light of a specific wavelength. In step S03, a second conductivity type semiconductor layer is formed on the central region of the intrinsic layer. The peripheral region of the intrinsic layer surrounding the central region is exposed. Finally, in step S04, a metal silicide layer is formed on the edge of the peripheral region of the intrinsic layer. The metal silicide layer reduces the amount of light that passes through the edge and enters the intrinsic layer and is absorbed by the intrinsic layer. The technical details of the other elements are as described above and will not be explained again here.

[0027] The above-described embodiments illustrate embodiments of the present invention and describe the characteristic configuration of the present invention. The present invention is not limited to the above embodiments. 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 shall be based on the claims. [Explanation of Symbols]

[0028] 100 photodiodes 110 First Conductivity Semiconductor Layer 120 Intrinsic layer 130 Second Conductivity Semiconductor Layer 140 Protective layer 150 Metal silicide layer 160 Upper electrode 170 Lower electrode I1 line segment I2 line segment

Claims

1. It is a photodiode, A first conductive semiconductor layer and An intrinsic layer is placed on the first conductive semiconductor layer and generates a photocurrent after absorbing light of a specific wavelength, A second conductive semiconductor layer is placed on the central region of the intrinsic layer, exposing the peripheral region of the intrinsic layer surrounding the central region, The intrinsic layer includes a metal silicide layer installed at the edge of the peripheral region of the intrinsic layer, A photodiode in which the metal silicide layer reduces the amount of light that passes through the edge and enters the intrinsic layer and is absorbed by the intrinsic layer.

2. The photodiode according to claim 1, characterized in that the metal of the metal silicide layer is one selected from the group consisting of nickel (Ni), platinum (Pt), gold (Au), cobalt (Co), chromium (Cr), vanadium (V), titanium (Ti), and tungsten (W).

3. The photodiode according to claim 1, characterized in that the depth of the metal silicide layer is 1 micrometer (μm) or less.

4. The photodiode according to claim 1, characterized in that the width of the metal silicide layer is equal to half the width of the peripheral region of the intrinsic layer.

5. The photodiode according to claim 1, characterized in that the thickness of the intrinsic layer is 50 to 70 micrometers (μm).

6. The aforementioned intrinsic layer is an N-type light-doped silicon layer, the dopant is phosphorus (P), and the doping concentration is 10 １２～１３ cm －３ The photodiode according to claim 1, characterized in that it is the same as the photodiode according to claim 1.

7. A method for manufacturing a photodiode, The steps include forming a first conductive semiconductor layer, The steps include forming an intrinsic layer on the first conductive semiconductor layer, which absorbs light of a specific wavelength and generates a photocurrent afterward, The steps include forming a second conductive semiconductor layer, which is placed on the central region of the intrinsic layer and exposes the peripheral region of the intrinsic layer surrounding the central region, The step includes forming a metal silicide layer on the edge of the peripheral region of the intrinsic layer, A method for manufacturing a photodiode, wherein the metal silicide layer reduces the amount of light that passes through the edge and enters the intrinsic layer and is absorbed by the intrinsic layer.

8. The manufacturing method according to claim 7, characterized in that the step of forming the metal silicide layer is a step of performing metal ion implantation and diffusion.

9. The manufacturing method according to claim 8, characterized in that the metal used for metal ion implantation and diffusion is selected from the group consisting of nickel (Ni), platinum (Pt), gold (Au), cobalt (Co), chromium (Cr), vanadium (V), titanium (Ti), and tungsten (W).

10. The manufacturing method according to claim 7, characterized in that the step of forming the metal silicide layer is a step of forming a nickel silicide layer with a depth of 1 micrometer (μm) or less.

11. The manufacturing method according to claim 7, characterized in that the step of forming the metal silicide layer is a step of forming a nickel silicide layer whose width is equal to half the width of the peripheral region of the intrinsic layer.

12. The step of forming the intrinsic layer involves a thickness of 50 to 70 micrometers (μm), a dopant of phosphorus (P), and a doping concentration of 10. １２～１３ cm －３ The manufacturing method according to claim 7, characterized in that it is a step of forming an N-type light-doped silicon layer.

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