KR102664498B1 - UIM(Universal Impedance Matching) anti-reflection coating, UIM anti-reflection coating silicon photodetector that prevents reflection regardless of incident angle and polarization state in the visible and near-infrared wavelength bands and method for manufacturing the same - Google Patents

Abstract

The present invention discloses an anti-reflective film that prevents reflection regardless of incident angle and polarization state in the visible and near-infrared wavelength bands, an anti-reflective film silicon photodetector, and a method of manufacturing the same. According to the present invention, there is provided a silicon photodetector that generates a photocurrent corresponding to the incidence of light through a PIN junction, comprising: a metal layer; an intrinsic semiconductor layer located on the metal layer and made of unique crystalline silicon; an N-type semiconductor layer located on the intrinsic semiconductor layer and made of n-type doped silicon; a P-type semiconductor layer located on the intrinsic semiconductor layer and made of p-type doped silicon; a cathode located on the N-type semiconductor layer; an anode located on the P-type semiconductor layer; and an anti-reflective film located on the P-type semiconductor layer, wherein the anti-reflective film includes a first layer located on the P-type semiconductor layer and formed of SiO ₂ and SiO ₂ spaced apart from the first layer by a predetermined distance. a second layer formed of, and a spacing layer disposed between the first layer and the second layer and formed of TiO ₂ , wherein the anti-reflective film is a structural double layer where the first layer and the second layer together with the spacing layer It is formed of a metamaterial, and utilizes the nonlocality of the electromagnetic wave response to incident light to create spatiotemporal dispersion in which the effective refractive index changes depending on the frequency and angle of incidence of the incident light. An anti-reflective silicon photodetector that implements an anti-reflective film is provided.

Description

Anti-reflection film, anti-reflection film silicon photodetector and manufacturing method thereof that prevent reflection regardless of incident angle and polarization state in the visible and near-infrared wavelength bands {UIM (Universal Impedance Matching) anti-reflection coating, UIM anti-reflection coating silicon photodetector that prevents reflection regardless of incident angle and polarization state in the visible and near-infrared wavelength bands and method for manufacturing the same}

The present invention relates to an anti-reflective film that prevents reflection regardless of incident angle and polarization state in the visible and near-infrared wavelength bands, an anti-reflective film silicon photodetector, and a method of manufacturing the same.

The development of photodetectors is receiving a lot of attention in various IT industry fields such as CIS, IoT sensors, autonomous driving sensors, solar sensors, and industrial robots, as well as in the broader semiconductor industry, and will be used as a key component in many future industrial technology fields. You can.

In particular, the smartphone market, the largest market for image sensors, is growing steadily, and demand for automobiles and industrial applications is also expected to continue to increase, leading to market expansion in the future.

A photodetector is a device that utilizes the characteristic of electronic devices that change their electrical characteristics depending on light. When light is incident on the light receiving part of the device, it has the function of absorbing light energy internally and converting it into electrical energy. Here, light absorption refers to exciting electrons to a state greater than the energy gap by light, and the need for a photodetector that controls light without loss due to reflection is emerging.

In general, a photodetector creates a PIN junction on a substrate and generates a carrier that absorbs photon energy when light is incident on the junction interface. The flow of this carrier generates a current, and through interaction with an external circuit, a photocurrent, an electrical signal corresponding to the optical signal, is generated.

To measure the generated photocurrent, wire bonding is performed to connect the circuit board and metal pad.

Specifically, in a semiconductor photodetector, when the photon energy of incident light is greater than the band gap energy of the semiconductor, light absorption occurs within the device to create an electron-hole pair. Here, when light is received from a reverse biased PIN junction, the photocurrent increases. At this time, the photo current does not depend on the reverse bias voltage but on the amount of light. The generated current is transmitted to the outside through a conductor made through wire bonding, and the performance of the device is confirmed based on the measured photocurrent.

Meanwhile, photodetectors have different electromagnetic properties depending on the type of material made up of the top or surface of the device, so the materials are different for each field to which they are applied.

Photodetectors are generally manufactured using silicon or silicon nitride (Si ₃ N ₄ ), which are highly compatible with the CMOS process, and are materials that are attracting attention in the sensor and artificial intelligence fields.

Silicon photodetectors have different degrees of reflection control depending on the angle of incidence and polarization state, and when light is incident under different conditions while changing the wavelength of light, performance deteriorates due to lower light absorption and responsivity. This happens.

In general, when light passes through the boundary between two materials with different optical properties, it may be partially or completely reflected due to mismatch in impedance or admittance. Therefore, in order to develop a high-performance photo detector, Efforts to design an anti-reflective film that controls the reflection of light in the light receiving part of a photodetector have continued.

Representative anti-reflection technologies include quarter-wave anti-reflection coating, multi-layer anti-reflection coating, and inhomogeneous anti-reflection coating for light detectors. has been used in

However, the 1/4-wave antireflection film formed using silicon nitride has the limitation that reflection is controlled only in a specific wavelength band, so it is still difficult to improve the impedance matching and process conditions required for high-performance photodetectors in a wide spectral range. It's a challenge.

Meanwhile, photo detectors using multilayer anti-reflection films and non-homogeneous anti-reflection films have been developed to achieve anti-reflection in a wide spectral range, but they still show low absorption depending on the incident angle and polarization state, and performance such as light reactivity deteriorates under design conditions. There are problems such as

In addition, multilayer anti-reflective films and heterogeneous anti-reflective films have the disadvantage that the thickness of the anti-reflective film increases compared to the wavelength and the complexity of the structure forming the anti-reflective film increases, which increases the complexity of the manufacturing process and increases costs.

Therefore, in order to maximize the performance of high-performance photodetectors, there is a need to propose a design and application technology for a silicon photodetector with an anti-reflection film that is thin compared to the wavelength and is non-reflective regardless of the frequency, angle of incidence, and polarization state of the incident light. There is.

Meanwhile, according to the Universal Impedance Matching (UIM) theory, in order to block the reflection of light regardless of the frequency, incident angle, and polarization state of the incident light, a medium variable (( A material parameter is required for an anti-reflective film, and this can be implemented with a material whose effective material parameter has spatio-temporal dispersion.

More specifically, spatiotemporal dispersion can be realized by designing a structural double layer metamaterial that utilizes two media layers with different refractive indices to be spaced apart to a thickness smaller than the wavelength.

In other words, the effective medium variable of a metamaterial formed with a structure thinner than the wavelength is that the effective refractive index changes depending on the frequency and angle of incidence of light through a non-local electromagnetic response depending on the incident light. It can have spatiotemporal distribution.

Therefore, by utilizing the spatiotemporal dispersion of metamaterials, it is possible to form a UIM anti-reflective film that controls the reflection of light regardless of the incident angle and polarization state in a wide wavelength range from visible light to near-infrared, and a silicon photodetector using the UIM anti-reflective film can be formed. There is a need for design and implementation techniques to be proposed.

At the same time, photodetectors capable of controlling the reflection of light in visible and near-infrared wavelengths can be used as key components in many future industrial technology fields, so there is a need to propose technologies that increase the performance and efficiency of the device.

KR registered patent 10-2370709

In order to solve the problems of the above-mentioned prior art, the present invention is to control the energy loss due to reflection of visible light and near-infrared light regardless of the change in incident angle and polarization state in the wavelength band of visible light and near-infrared light, which can improve energy transferability. We would like to propose an anti-reflective film that prevents reflection regardless of incident angle and polarization state, an anti-reflective film silicon photodetector, and a method of manufacturing the same.

In order to achieve the above-described object, according to one embodiment of the present invention, there is provided a silicon photodetector that generates a photocurrent corresponding to the incidence of light through a PIN junction, comprising: a metal layer; an intrinsic semiconductor layer located on the metal layer and made of unique crystalline silicon; an N-type semiconductor layer located on the intrinsic semiconductor layer and made of n-type doped silicon; a P-type semiconductor layer located on the intrinsic semiconductor layer and made of p-type doped silicon; a cathode located on the N-type semiconductor layer; an anode located on the P-type semiconductor layer; and an anti-reflective film located on the P-type semiconductor layer, wherein the anti-reflective film includes a first layer located on the P-type semiconductor layer and formed of SiO ₂ and SiO ₂ spaced apart from the first layer by a predetermined distance. a second layer formed of, and a spacing layer disposed between the first layer and the second layer and formed of TiO ₂ , wherein the anti-reflective film is a structural double layer where the first layer and the second layer together with the spacing layer It is formed of a metamaterial, and utilizes the nonlocality of the electromagnetic wave response to incident light to create spatiotemporal dispersion in which the effective refractive index changes depending on the frequency and angle of incidence of the incident light. An anti-reflective silicon photodetector that implements an anti-reflective film is provided.

The total thickness of the first layer, the second layer, and the spacing layer has a thickness smaller than the wavelength of the incident light, and the second layer has a thickness of 7 to 9 times the thickness of the first layer. And, the spacing layer may be formed to have a thickness of 3 to 3.5 times the thickness of the first layer.

The spacing layer may be formed to be 0.04 to 0.06 times the central wavelength of 750 nm of the incident light.

The first layer, the second layer, and the spacing layer may be formed through a sputtering process.

According to another aspect of the invention, a first layer formed of SiO ₂ ; a second layer formed of SiO ₂ and spaced apart from the first layer by a predetermined distance; and a spacing layer disposed between the first layer and the second layer and formed of TiO ₂ , wherein the spacing layer forms a structural double layer together with the spacing layer and is formed of a metamaterial, and has nonlocality of the electromagnetic wave response to incident light. ) is provided to provide an anti-reflective film that implements spatiotemporal dispersion in which the effective refractive index changes depending on the frequency and angle of incidence of the incident light.

According to another aspect of the present invention, there is provided a method of manufacturing a silicon photodetector that generates a photocurrent corresponding to incident light through a PIN junction, comprising: forming an intrinsic semiconductor layer made of intrinsic crystalline silicon on a metal layer; forming an n-type semiconductor layer made of n-type doped silicon on the intrinsic semiconductor layer; forming a p-type semiconductor layer made of p-type doped silicon on the intrinsic semiconductor layer; forming metal pads constituting a cathode and an anode on the N-type semiconductor layer and the P-type semiconductor layer; and forming an anti-reflective film on the P-type semiconductor layer using sputtering, wherein the anti-reflective film includes a first layer located on the P-type semiconductor layer and formed of SiO ₂ , the first layer and a predetermined amount. It includes a second layer spaced apart by a distance and formed of SiO ₂ , and a spacing layer disposed between the first layer and the second layer and formed of TiO ₂ , wherein the anti-reflective film includes the first layer and the second layer. It is formed of a metamaterial as a structural double layer with a spacing layer, and utilizes the nonlocality of the electromagnetic wave response to incident light to change the effective refractive index according to the frequency and incident angle of the incident light. A method for manufacturing an anti-reflective silicon photodetector implementing spatiotemporal dispersion is provided.

According to the present invention, it is possible to design an anti-reflective film structure that blocks reflection of light or electromagnetic waves by matching the impedance of each material layer regardless of the frequency, incident angle, and polarization state of light in the visible and near-infrared regions.

In addition, according to the present invention, the size of the photo detector can be reduced by designing an anti-reflective film that can control the reflection of light at any angle of incidence compared to an anti-reflective film such as a multi-layer anti-reflective film with a large thickness compared to the wavelength.

Furthermore, according to the present invention, an anti-reflective film based on the universal impedance matching theory that controls the reflection of light by utilizing the spatiotemporal dispersion of a material whose effective refractive index changes depending on the frequency and angle of incidence of light is combined with a silicon photodetector. It can reduce the reflection loss of optical composite devices used in future industries such as various sensors and artificial intelligence fields and improve the output light response.

1 is a schematic diagram of an anti-reflective silicon photodetector according to an embodiment of the present invention.
Figure 2 is a detailed structural diagram of an anti-reflective membrane according to this embodiment.
Figure 3 is a diagram showing the light absorption rate of light or electromagnetic waves of different silicon photodetectors.
Figure 4 is a view showing an optical microscope and a scanning electron microscope image (SEM) of an anti-reflective silicon photodetector according to an embodiment of the present invention.
Figure 5 is a diagram showing data compared by actually measuring light absorption and light responsivity in the visible light region of a silicon photodetector with an anti-reflection film according to this embodiment and a silicon photodetector without an anti-reflection film combined. .
FIG. 6 is a graph showing data compared by measuring absorption and responsivity in the near-infrared region of an anti-reflective silicon photodetector according to this embodiment and a general silicon photodetector not combined with an antireflective film.
Figure 7 shows the light absorption and reactivity when light or electromagnetic waves in the visible and near-infrared regions are incident at various angles of incidence on an anti-reflective silicon photodetector according to this embodiment and a general silicon photodetector without an antireflective film combined. This is a graph showing the data compared by measuring responsivity.
Figure 8 is a flowchart showing the process of forming a silicon photodetector on which an anti-reflective film of the present invention is deposited.

Since the present invention can make various changes and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail.

However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

Figure 1 is a schematic diagram of an anti-reflective film silicon photodetector according to an embodiment of the present invention, and Figure 2 is a detailed structural diagram of an anti-reflective film according to this embodiment.

The silicon photodetector according to this embodiment generates a carrier that absorbs photon energy when light is incident, and the flow of the carrier generates a current and interacts with an external circuit to generate a photocurrent, which is an electrical signal corresponding to the optical signal. generates

Referring to FIG. 1, the silicon photodetector 110 according to this embodiment includes a metal layer 111, an intrinsic semiconductor layer 112, an N-type semiconductor layer 113, a P-type semiconductor layer 114, and an insulating layer 115. ), a cathode 116, an anode 117, and an anti-reflective film 120.

The metal layer 110 forms the electrode of the photo detector itself and is made of a metal material such as Au.

The intrinsic semiconductor layer 112 for PIN junction may be an intrinsic crystalline silicon substrate.

The N-type semiconductor layer 113 may be n-type doped silicon formed through an ion implantation process, and the P-type semiconductor layer 114 may be p-type doped silicon.

The insulating layer 115 may be formed of silicon dioxide (SiO ₂ ).

A cathode (116) is located on the N-type semiconductor layer (113), and a plurality of anodes (for example, three anodes (117)) are located on the P-type semiconductor layer (114).

Additionally, the anti-reflection film 120 is located on the P-type semiconductor layer 114.

According to this embodiment, when forming the intrinsic semiconductor layer 112, a small amount of n-type doping is performed, but the unique characteristics of crystalline silicon can be maintained.

Therefore, the N-type semiconductor layer 113 and the P-type semiconductor layer 114 can form a PIN junction with the intrinsic semiconductor layer 112 between them, and the N-type semiconductor layer 113 and the P-type semiconductor layer 114 Photoresponsiveness can be measured by measuring the photocurrent formed at the PIN junction through the cathode 116 and anode 117 coupled thereto.

In addition, the anti-reflective film 120 according to this embodiment can be located in the light receiving part of the silicon photodetector 110 to control reflection regardless of the frequency or wavelength, incident angle, and polarization state of the visible and near-infrared wavelength bands. And, the anti-reflective film 120 can be formed based on the conventional universal impedance matching theory.

According to the Universal Impedance Matching theory, an anti-reflective film that controls the reflection of light (or electromagnetic waves) incident from the air to the substrate regardless of the frequency or wavelength, incident angle, and polarization state of the visible and near-infrared wavelength bands. It can be formed as a metamaterial that meets the universal impedance matching conditions between air and the substrate, and the metamaterial can be formed as a structural double layer made up of a layer with a thickness thinner than the wavelength of the incident light. In addition, the structural double layer can reduce energy loss due to reflection of light or electromagnetic waves by combining with the light receiving part of the silicon photodetector, thereby improving energy transfer to the silicon photodetector.

The anti-reflective film according to this embodiment has a relative permittivity and relative permeability that satisfies Equation 1 below, blocking reflection regardless of the frequency or wavelength, incident angle, and polarization state of incident light. .

,

는 상대 유전율이고,

는 공기와 무반사막(120) 아래에 위치하는 기판을 형성하는 매질에 대한 빛의 기하 평균 어드미턴스(geometric mean admittance)이고,

은 기하 평균 방향 코사인(geometric mean directional cosine), d는 무반사막의 두께이고,

,

는 상대 투자율, k는 파수(wave number)를 나타내며,

는 빛의 각주파수이다. here,

,

is the relative permittivity,

is the geometric mean admittance of light with respect to air and the medium forming the substrate located below the anti-reflective film 120,

is the geometric mean directional cosine, d is the thickness of the anti-reflective film,

,

represents the relative permeability, k represents the wave number,

is the angular frequency of light.

와

는 다음과 같이 표현될 수 있다. More specifically,

and

can be expressed as follows.

은 n번 매질에 수직으로 입사하는 빛의 어드미턴스,

은 n번 매질에서의 방향코사인,

은 n번 매질의 유전율이고,

은 n번 매질의 투자율을 나타낸다. Here, n is the type of medium, including air or silicon substrate, respectively,

is the admittance of light incident perpendicularly to n medium,

is the direction cosine in medium n,

is the permittivity of the nth medium,

represents the permeability of nth medium.

Referring to FIG. 2, the anti-reflective film 120 is separated from the first layer 121 located on the substrate 114 by a predetermined distance and is separated from the second layer 123 and the first layer. It may include a spacing layer 122 disposed between the second layers.

The anti-reflective film 120 according to this embodiment may be formed of a metamaterial through a structural double layer including the first layer 121 and the second layer 123 and a spacing layer 122 disposed between them.

Preferably, the first layer 121 and the second layer 123 may be made of silicon dioxide (SiO ₂ ) having a refractive index in the range of 1.40 to 1.55.

The spacing layer 122 is composed of crystalline silicon (c-Si), heterogeneous silicon (a-Si), and poly-silicon (poly-Si) having a greater refractive index than the first layer 121 and the second layer 123. It can be.

Considering the complex refractive index of the material, the attenuation coefficient, an imaginary number representing the attenuation of light, must converge to 0 in the wavelength band of the incident light to prevent loss due to absorption inside the anti-reflective film. and is transmitted to the light detector.

Semiconductor materials such as crystalline silicon, heterogeneous silicon, and polysilicon have an attenuation coefficient greater than 0 in the visible light range, so when light is incident, absorption occurs within the anti-reflective film.

Therefore, according to this embodiment, the spacing layer 122 is formed using TiO ₂ to prevent absorption in the anti-reflective film regardless of the incident angle and polarization state in the wide wavelength range of visible light and near-infrared light, thereby reducing light loss. It can reduce and improve device performance.

According to this embodiment, the total thickness of the first layer 121, the spacing layer 122, and the second layer 123 may have a thickness smaller than the wavelength of incident light.

In more detail, depending on the refractive index of the material forming the structural double layer, the second layer 123 may be formed to have a thickness of 7 to 9 times the thickness of the first layer 121, and the spacing layer 122 may be formed with a thickness of 7 to 9 times the thickness of the first layer 121. (121) It can be formed to a thickness of 3 to 3.5 times the thickness.

In addition, the spacing layer 122 may be formed to be 0.04 to 0.06 times the central wavelength of 750 nm, and preferably 0.056 times the wavelength of the incident light.

The structural double layer according to this embodiment is formed to have a thickness thinner than the wavelength of the incident light, so that nonlocality of the electromagnetic wave response to the incident light can be achieved, and by utilizing this nonlocality, the frequency and incident angle of the incident light can be adjusted. It is possible to implement spatio-temporal dispersion in which effective material parameters change.

As described above, the anti-reflective film 120 forming a structural double layer may have a relative dielectric constant and relative permeability corresponding to Equation 1 and Equation 2, and the frequency or wavelength of the visible and near-infrared wavelength bands and the incident angle , and reflection can be controlled regardless of the polarization state.

Figure 3 is a diagram showing the light absorption rate of light or electromagnetic waves of different silicon photodetectors.

In Figure 3, the horizontal axis represents the wavelength or frequency of light, the vertical axis represents the angle of incidence of light, and the absorption rate of light according to the wavelength, angle of incidence, and polarization state of light.

More specifically, the axis of the graph in FIG. 3 shows data on light incident at an incident angle of 75 degrees or less in a wavelength range of 400 nm to 1100 nm.

Figures 3a and 3b are diagrams showing the absorption rate (1-reflection or absorption) according to the TE polarization state and the absorption rate according to the TM polarization state of the silicon photodetector without an anti-reflection film attached.

In addition, Figures 3c to 3d are diagrams showing the absorption rate according to TE polarization state and the absorption rate according to TM polarization state of a silicon photodetector combined with a 1/4-wave antireflection film using silicon nitride (Si ₃ N ₄ ).

Figures 3c to 3d show the absorption rate when an ideal 1/4-wave anti-reflection (QAR) film according to the prior art is formed with silicon nitride on a silicon substrate.

Here, the 1/4-wavelength antireflection film condition can be explained with reference to Equation 3 below.

는 입사하는 빛의 파장이다.Here, t is the thickness, n is the refractive index of silicon nitride,

is the wavelength of the incident light.

Silicon photodetector and silicon nitride (Si ₃ N ₄ ) Silicon photodetector is still widely used as a photodetector material applied to sensors, cameras, realistic media, etc. due to its efficient characteristics in the visible and near-infrared regions, so all-round impedance matching It was identified as a good material group for comparison with the anti-reflective film of the device, and experiments were conducted.

Figures 3e to 3f are diagrams showing the absorption rate according to the TE polarization state and the absorption rate according to the TM polarization state of the anti-reflective silicon photodetector according to this embodiment.

Referring to FIG. 3, it can be seen that the non-reflective silicon photodetector according to this embodiment exhibits a high light absorption rate because it controls light reflection regardless of the incident angle and polarization state in a wide wavelength band including visible light and near-infrared light. You can.

Figure 4 is a view showing an optical microscope and a scanning electron microscope image (SEM) of an anti-reflective silicon photodetector according to an embodiment of the present invention.

As shown in the optical microscope image of FIG. 4A, it can be confirmed that an anti-reflective film is deposited in the center of the silicon photodetector, and wire bonding is performed on the anode and cathode, respectively, to output an electrical signal.

Figure 4b shows a single layer image of a device in which silicon dioxide (SiO ₂ ) and titanium dioxide (TiO ₂ ) were deposited on a silicon substrate using sputter, a type of physical vapor deposition (PVD). .

At this time, in the structural double layer of the anti-reflective film, the first layer 121 made of silicon dioxide (SiO ₂ ) is formed with a thickness of 16 nm, and the second layer 123 is formed with a thickness of 120 nm. It shows that the spacing layer made of titanium (TiO ₂ ) was formed at 42 nm.

Meanwhile, the deposition method using sputter has the advantage of being economical as it can be deposited quickly and in a large area and can be processed at a low cost. In terms of the overall process, chemical vapor deposition (CVD) can be used. ) or through a simple process using Physical Vapor Deposition (PVD), an anti-reflective film can be implemented in a large area, gaining advantages in terms of cost and mass production.

In addition, this embodiment is a simple medium layer using chemical vapor deposition and physical vapor deposition methods in preparation for a non-homogeneous anti-reflection layer that is difficult to process due to a complex structure such as a moth-eye anti-reflection layer. Deposition can improve the productivity of anti-reflective films.

Figures 5a to 5f show data compared by actually measuring the light absorption and light responsivity in the visible light region of the anti-reflective film silicon photodetector according to this embodiment and the silicon photodetector not combined with the antireflective film. It is a drawing.

More specifically, Figures 5a to 5f show the light absorption rate and light according to arbitrary incident angles and polarization states of 480nm, 550nm, and 650nm wavelengths in the visible light band in an anti-reflective silicon photodetector and a general silicon photodetector according to this embodiment. The reactivity was printed and compared.

The horizontal axis represents the angle of incidence, the left vertical axis represents light reactivity, and the right vertical axis represents light absorption.

Additionally, the optical reactivity on the left vertical axis is the output photo current (current, unit: ampere [A]) divided by the intensity of incident light (power, unit: watt [W]), and can be expressed as follows.

Figures 5a and 5b show the light responsivity and light absorption according to the angle of incidence when light with a wavelength of 480 nm is incident on the non-reflective silicon photodetector and the general silicon photodetector according to this embodiment, depending on the polarization state. It is shown.

Figures 5c and 5d show the light responsivity and light absorption according to the angle of incidence when light with a wavelength of 550 nm is incident on the non-reflective silicon photodetector and the general silicon photodetector according to this embodiment, depending on the polarization state. It is shown.

Figures 5e and 5f show the light responsivity and light absorption according to the angle of incidence when light with a wavelength of 650 nm is incident on the non-reflective silicon photodetector and the general silicon photodetector according to this embodiment, depending on the polarization state. It is shown.

Referring to FIGS. 5A to 5F, it can be seen that the photocurrent and photoresponsivity of the non-reflective silicon photodetector according to this embodiment have a similar tendency to the absorption rate confirmed by reflectance measurement, and that the photocurrent and photoresponsivity of the anti-reflective silicon photodetector according to this embodiment have a similar tendency to that of a general silicon photodetector. Compared to , it can be seen that the performance indicators in the visible light wavelength band are better.

That is, compared to a general silicon photodetector, the non-reflective silicon photodetector according to this embodiment is efficient in light absorption and light reactivity regardless of polarization state in the incident angle range of 75 degrees or less when light with a wavelength in the visible light region is incident. You can check that it has performance.

Figures 6a to 6d are graphs showing data compared by measuring absorption and responsivity in the near-infrared region of an anti-reflective film silicon photodetector according to this embodiment and a general silicon photodetector without an antireflection film combined. am.

More specifically, FIGS. 6A to 6F show optical absorption and optical reactivity according to arbitrary incident angles and polarization states of 800 nm and 900 nm wavelengths in the near-infrared band to the non-reflective film silicon photodetector and the general silicon photodetector according to this embodiment. This shows a graph for comparison.

The horizontal axis represents the angle of incidence, the left vertical axis represents light reactivity, and the right vertical axis represents light absorption.

Figures 6a and 6b show the light responsivity and light absorption according to the angle of incidence when light with a wavelength of 800 nm is incident on the non-reflective film silicon photodetector and the general silicon photodetector according to this embodiment, depending on the polarization state. It is shown.

Figures 6c and 6d show the light responsivity and light absorption according to the angle of incidence when light with a wavelength of 900 nm is incident on the non-reflective silicon photodetector and the general silicon photodetector according to this embodiment, depending on the polarization state. It is shown.

Referring to FIGS. 6A to 6D, it can be seen that the photocurrent and photoresponsivity of the anti-reflective silicon photodetector according to this embodiment have a similar tendency to the absorption rate confirmed by reflectance measurement, and are similar to those of a general silicon photodetector. When compared, it can be seen that the performance indicators in the near-infrared wavelength band are superior.

That is, as a result of graph analysis of FIGS. 6A to 6D, by depositing an anti-reflective film according to this embodiment on a conventional silicon photodetector, polarization is achieved at an incident angle of 75 degrees or less and in a long frequency range of visible light and near-infrared region. Regardless, reflection of light can be prevented. Through this, the optical detector according to this embodiment can be applied to future industries such as optical sensors such as artificial intelligence sensors, IoT sensors, and autonomous driving sensors, and realistic media such as AR, VR, and XR.

FIGS. 7A to 7F show light absorption rates when light or electromagnetic waves in the visible and near-infrared regions are incident at various incident angles on an anti-reflective silicon photodetector according to this embodiment and a general silicon photodetector without an antireflective film combined. This is a graph showing the data compared by measuring the responsiveness.

In more detail, Figures 7a to 7f show light with frequencies or wavelengths in the visible and near-infrared bands being applied to an anti-reflective film silicon photodetector and a general silicon photodetector according to this embodiment at different incident angles of 0 degrees, 25 degrees, and 50 degrees, respectively. This is a drawing where the data was output.

Figures 7a and 7b show the light absorption and reactivity measured when light in the visible and near-infrared wavelength bands is incident on a silicon photodetector combined with an antireflection film and a general silicon photodetector regardless of polarization state at an incident angle of 0 degrees. (responsivity) is shown graphically.

Figures 7c and 7d show light absorption measured by incident light in the visible and near-infrared wavelength bands on an anti-reflective film silicon photodetector and a general silicon photodetector according to this embodiment, regardless of polarization state, at an incident angle of 25 degrees. And the responsivity is shown graphically.

Figures 7e and 7f show light absorption measured when light in the visible and near-infrared wavelength bands is incident on an anti-reflective film silicon photodetector and a general silicon photodetector according to this embodiment regardless of polarization state at an incident angle of 50 degrees. And the responsiveness is shown graphically.

Referring to FIGS. 7A to 7F, compared to a general silicon photodetector, the non-reflective silicon photodetector according to this embodiment shows the TE and TM polarization states when the incident angle is set to 0, 25, and 50 degrees in the wavelength range from 400 nm to 1000 nm. Efficient performance can be confirmed in terms of light responsivity and light absorption.

Figure 8 is a flowchart showing the process of forming a silicon photodetector on which an anti-reflective film of the present invention is deposited.

Referring to FIG. 8, an intrinsic crystalline silicon (c-Si) substrate is formed on the metal layer 111 made of Au (step 800). At this time, the formed substrate may be doped with a small amount of n-type, but the unique characteristics of crystalline silicon can be maintained.

The metal layer 111 is formed using sputtering, a method of physical vapor deposition (PVD).

Next, through an ion implantation process, N-type and P-type semiconductor layers doped with n-type and p-type are formed on a unique crystalline silicon (c-Si) substrate with an insulating layer in between to form a PIN junction. (step 802). By forming a PIN junction, a carrier that absorbs photon energy is created, and the flow caused by the carrier generates a current. By interacting with an external circuit, a photocurrent, an electrical signal corresponding to an optical signal, is generated.

Three anode and one cathode metal pads are formed from aluminum where the PIN joint is formed (step 804).

A first layer 121 of an anti-reflective film is formed on a metal pad using silicon dioxide (SiO ₂ ) having a refractive index of 1.455 (step 806).

Next, a separation layer is formed using titanium dioxide (TiO ₂ ) having a refractive index of 2.4 to 2.9 (step 808).

Thereafter, the second layer 123 is formed using silicon dioxide (SiO ₂ ) having a refractive index of 1.455 (step 810).

In steps 806 to 810, the first layer 121, the spacing layer 122, and the second layer 123 are formed using sputtering, which is a physical vapor deposition (PVD) method.

The sputtering process of depositing each layer of the anti-reflective film has the advantage of being economical as it can be deposited quickly, over a large area, and at a low cost, allowing the process to proceed efficiently and stably.

Finally, wire bonding is performed between the aluminum metal pad and the circuit board to form a system that can measure the generated current (step 812).

Here, the purpose of wire bonding is to attach wires to the anode and cathode created in step 804 and connect them to the metal pad of the circuit board to measure photocurrent.

The above-described embodiments of the present invention have been disclosed for illustrative purposes, and those skilled in the art will be able to make various modifications, changes, and additions within the spirit and scope of the present invention, and such modifications, changes, and additions will be possible. should be regarded as falling within the scope of the patent claims below.

Claims (7)

A silicon photodetector that generates a photocurrent corresponding to the incidence of light through a PIN junction, comprising:
metal layer;
an intrinsic semiconductor layer located on the metal layer and made of unique crystalline silicon;
an N-type semiconductor layer located on the intrinsic semiconductor layer and made of n-type doped silicon;
a P-type semiconductor layer located on the intrinsic semiconductor layer and made of p-type doped silicon;
a cathode located on the N-type semiconductor layer;
an anode located on the P-type semiconductor layer; and
Includes an anti-reflective film located on the P-type semiconductor layer,
The anti-reflective film is located on the P-type semiconductor layer and includes a first layer formed of SiO ₂ , a second layer spaced apart from the first layer by a predetermined distance and formed of SiO ₂ , and between the first layer and the second layer. It is disposed in and includes a spacing layer formed of TiO ₂ ,
The anti-reflective film is formed of a metamaterial in which the first layer and the second layer form a structural double layer with the spacing layer, and utilizes the nonlocality of the electromagnetic wave response to the incident light to determine the frequency and frequency of the incident light. Implements spatiotemporal dispersion in which the effective refractive index changes depending on the angle of incidence.
The total thickness of the first layer, the second layer, and the spacing layer has a thickness smaller than the wavelength of the incident light,
The second layer is formed in the range of 112 to 144 nm with a thickness of 7 to 9 times the thickness of the first layer, and the spacing layer is formed in the range of 30 nm to 45 nm. delete delete According to paragraph 1,
The first layer, the second layer, and the spacing layer are an anti-reflective silicon photodetector formed through a sputtering process. a first layer formed of SiO ₂ ;
a second layer formed of SiO ₂ and spaced apart from the first layer by a predetermined distance; and
It is disposed between the first layer and the second layer and includes a spacing layer formed of TiO ₂ ,
The first layer and the second layer are formed of a metamaterial by forming a structural double layer together with the spacing layer, and utilize the nonlocality of the electromagnetic wave response to the incident light according to the frequency and angle of incidence of the incident light. Implements spatiotemporal dispersion where the effective refractive index changes,
The total thickness of the first layer, the second layer, and the spacing layer has a thickness smaller than the wavelength of the incident light,
The second layer is formed in a range of 112 to 144 nm with a thickness of 7 to 9 times the thickness of the first layer, and the spacing layer is formed in a range of 30 nm to 45 nm. delete A method of manufacturing a silicon photodetector that generates a photocurrent corresponding to incident light through a PIN junction, comprising:
forming an intrinsic semiconductor layer made of intrinsic crystalline silicon on the metal layer;
forming an n-type semiconductor layer made of n-type doped silicon on the intrinsic semiconductor layer;
forming a p-type semiconductor layer made of p-type doped silicon on the intrinsic semiconductor layer;
forming metal pads constituting a cathode and an anode on the N-type semiconductor layer and the P-type semiconductor layer; and
Comprising the step of forming an anti-reflective film on the P-type semiconductor layer using sputtering,
The antireflection film includes a first layer located on the P-type semiconductor layer and formed of SiO ₂ , a second layer spaced apart from the first layer by a predetermined distance and formed of SiO ₂ , and the first layer and the second layer. It is disposed between and includes a spacing layer formed of TiO ₂ ,
The anti-reflective film is formed of a metamaterial in which the first layer and the second layer form a structural double layer with the spacing layer, and utilizes the nonlocality of the electromagnetic wave response to the incident light to determine the frequency and frequency of the incident light. Implements spatiotemporal dispersion in which the effective refractive index changes depending on the angle of incidence.
The total thickness of the first layer, the second layer, and the spacing layer has a thickness smaller than the wavelength of the incident light,
The second layer is formed to have a thickness of 7 to 9 times the thickness of the first layer, and the spacing layer is formed to have a thickness of 3 to 3.5 times the thickness of the first layer,
A method of manufacturing an anti-reflective silicon photodetector wherein the spacing layer is formed at 0.04 to 0.06 times the central wavelength of 750 nm of the incident light.