JP5363222B2 - Semiconductor light detection element and method for manufacturing semiconductor light detection element - Google Patents

Description

  The present invention relates to a semiconductor photodetector element and a method for manufacturing the semiconductor photodetector element.

  As a light detection device for detecting light in a specific wavelength band, the first light-receiving portion in which the second conductivity type impurity region is formed in the surface layer portion of the first conductivity type silicon substrate and the other surface layer portion of the silicon substrate. A semiconductor light-receiving element having a second light-receiving portion in which an impurity region of the second conductivity type is formed and a high-concentration first-conductivity type impurity region is formed in a lower layer portion of the second conductivity-type impurity region; A signal processing circuit that calculates the difference between the output of the light receiving unit and the output of the second light receiving unit is known (see, for example, Patent Document 1).

JP-A-2-240531

  In a semiconductor photodetecting element using a silicon substrate, it is generally possible to increase the spectral sensitivity characteristic on the long wavelength side by setting the thickness of the silicon substrate large. However, even when the thickness of the silicon substrate is set sufficiently large (for example, about 1.5 mm), it has been difficult to obtain sufficient spectral sensitivity characteristics in the near-infrared wavelength band of 1100 nm. For this reason, it has been considered difficult to realize a semiconductor photodetecting element having a practically sufficient spectral sensitivity characteristic only in a narrow wavelength band including the near infrared. In addition, if the silicon substrate is thick, not only the semiconductor photodetecting element itself becomes large, but also a new problem such as an increase in dark current may occur.

  The present invention provides a semiconductor photodetecting element using silicon and having a practically sufficient spectral sensitivity characteristic only in a narrow wavelength band including near infrared, and a method for manufacturing the semiconductor photodetecting element. For the purpose.

  A semiconductor photodetector according to the present invention includes a silicon substrate having a light incident surface on which light to be detected is incident and a back surface facing the light incident surface, and the silicon substrate has a first conductivity type on the back surface side. And a first conductivity type second semiconductor layer having a higher impurity concentration than the first semiconductor layer on the light incident surface side. The first semiconductor layer includes the first semiconductor layer. A third semiconductor region of a second conductivity type that forms a pn junction with the semiconductor layer is provided, the third semiconductor region is optically exposed, and irregular irregularities are formed. To do.

  In the semiconductor photodetecting element according to the present invention, the light in the long wavelength band including the near infrared out of the light incident from the light incident surface enters the silicon substrate and then travels long in the silicon substrate to enter the third semiconductor region. Reach the irregular irregularities formed. The reached light is reflected, scattered, or diffused by the irregular irregularities, and further travels in the silicon substrate. Thereby, a part of the light in the long wavelength band including the near infrared is absorbed by the first semiconductor layer without being transmitted through the semiconductor photodetecting element (silicon substrate) to generate carriers. Carriers generated by light in a long wavelength band including the near infrared move to the pn junction and are detected as a photocurrent.

  On the other hand, the light in the short wavelength band among the light incident from the light incident surface, after entering the silicon substrate, does not travel long in the silicon substrate and generates carriers at a relatively shallow position from the light incident surface. Since the second semiconductor layer is provided on the incident surface side, carriers generated by light in a short wavelength band are trapped by the second semiconductor layer and hardly move to the pn junction. For this reason, light in a short wavelength band hardly contributes to the light detection sensitivity of the semiconductor light detection element.

  From the above, the semiconductor photodetecting element according to the present invention has practically sufficient spectral sensitivity characteristics only in a narrow wavelength band including near infrared.

  Preferably, the thickness of the third semiconductor region is larger than the height difference of the irregular irregularities. In this case, a pn junction can be reliably formed.

  The method for manufacturing a semiconductor photodetector according to the present invention includes a first main surface and a second main surface facing each other, a first conductive type first semiconductor layer on the first main surface side, and a second main surface. Preparing a silicon substrate having a first conductivity type second semiconductor layer having an impurity concentration higher than that of the first semiconductor layer on the side, and forming a second conductivity type third semiconductor region in the first semiconductor layer And a step of irradiating the third semiconductor region with a pulsed laser beam to form irregular irregularities, and a step of heat-treating the silicon substrate on which irregular irregularities are formed. .

  According to the method for manufacturing a semiconductor photodetector element according to the present invention, a semiconductor photodetector element in which irregular irregularities are formed in the third semiconductor region can be obtained. As described above, this semiconductor photodetection element has practically sufficient spectral sensitivity characteristics only in a narrow wavelength band including near infrared.

  Preferably, the thickness of the third semiconductor region is made larger than the irregular height difference. In this case, a pn junction can be reliably formed even when irregular irregularities are formed by irradiation with pulsed laser light.

  Preferably, in the step of forming irregular irregularities, picosecond to femtosecond pulsed laser light is irradiated as pulsed laser light. In this case, irregular irregularities can be formed appropriately and easily.

  According to the present invention, there is provided a semiconductor photodetecting element using silicon, which has a practically sufficient spectral sensitivity characteristic only in a narrow wavelength band including near infrared, and a method for manufacturing the semiconductor photodetecting element. Can be provided.

It is a figure for demonstrating the manufacturing method of the photodiode which concerns on this embodiment. It is a figure for demonstrating the manufacturing method of the photodiode which concerns on this embodiment. It is a figure for demonstrating the manufacturing method of the photodiode which concerns on this embodiment. It is a figure for demonstrating the manufacturing method of the photodiode which concerns on this embodiment. It is the SEM image which observed the irregular unevenness | corrugation formed with the manufacturing method of the photodiode which concerns on this embodiment. It is a figure for demonstrating the manufacturing method of the photodiode which concerns on this embodiment. It is a figure for demonstrating the manufacturing method of the photodiode which concerns on this embodiment. It is a figure which shows the structure of the photodiode which concerns on this embodiment. It is a diagram which shows the change of the spectral sensitivity with respect to the wavelength in Example 1 and Comparative Example 1. FIG. It is a figure which shows the structure of the photodiode array which concerns on this embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

  First, with reference to FIGS. 1-7, the manufacturing method of photodiode PD1 which concerns on this embodiment is demonstrated. FIGS. 1-7 is a figure for demonstrating the manufacturing method of the photodiode which concerns on this embodiment.

First, a silicon substrate 1 made of silicon (Si) crystal and having a first main surface 1a and a second main surface 1b facing each other is prepared (see FIG. 1). The silicon substrate 1 has an n ⁻ type semiconductor region 3 having a low impurity concentration and located on the first main surface 1a side, and an n ⁺ type semiconductor region 5 having a high impurity concentration and located on the second main surface 1b side. Consists of. The n ⁺ type semiconductor region 5 has a higher impurity concentration than the n ⁻ type semiconductor region 3. The thickness of the silicon substrate 1 is, for example, about 500 μm. As the silicon substrate 1, a diffusion wafer, an epitaxial wafer, an SOI wafer or the like can be used.

The thickness of the n ⁻ type semiconductor region 3 is, for example, about 300 μm. The specific resistance of the n ⁻ type semiconductor region 3 is, for example, about 3 kΩ · cm, and functions as a high resistance layer. Here, “high resistance” indicates that the specific resistance is higher than that of the n ⁺ type semiconductor region 5 having a high impurity concentration. The thickness of the n ⁺ type semiconductor region 5 is, for example, about 200 μm. The specific resistance of the n ⁺ type semiconductor region 5 is, for example, about 0.01 Ω · cm. In this embodiment, “high impurity concentration” means, for example, an impurity concentration of about 1 × 10 ¹⁷ cm ⁻³ or more, and “+” is attached to the conductivity type, and “low impurity concentration” is an impurity The concentration is about 1 × 10 ¹⁵ cm ⁻³ or less, and “−” is attached to the conductivity type. Examples of n-type impurities include phosphorus (P).

Next, ap ⁺ type semiconductor region 7 and an n ⁺ type semiconductor region 9 are formed in the n ⁻ type semiconductor region 3 (see FIG. 2). The p ⁺ -type semiconductor region 7 is formed by diffusing p-type impurities in a high concentration from the first main surface 1a side in the n ⁻ -type semiconductor region 3 using a mask having an opening at the center. An example of the p-type impurity is boron (B). The n ⁺ -type semiconductor region 9 uses an n-type impurity from the first major surface 1a side in the n ⁻ -type semiconductor region 3 so as to surround the p ⁺ -type semiconductor region 7 using another mask having an opening in the peripheral region. Is diffused at a higher concentration than the n ⁻ type semiconductor region 3. The thickness of the p ⁺ type semiconductor region 7 is, for example, about 3 μm, and the sheet resistance is, for example, 44 Ω / sq. It is. The thickness of the n ⁺ type semiconductor region 9 is, for example, about 1.5 μm, and the sheet resistance is, for example, 12 Ω / sq. It is.

Next, the irregular laser beam 11 is formed by irradiating the p ⁺ type semiconductor region 7 with the pulse laser beam PL (see FIG. 3). Here, as shown in FIG. 4, the silicon substrate 1 is disposed in the chamber C, and the pulse laser light PL is transmitted from the pulse laser generator PLD disposed outside the chamber C to the silicon substrate 1 (p ⁺ type semiconductor region). 7). Chamber C has a gas inlet G _IN and the gas discharge section G _OUT, inert gas (e.g., nitrogen gas or argon gas) is introduced through the gas inlet port G _IN discharged from the gas discharge portion G _OUT Thus, an inert gas flow _Gf is formed in the chamber C. Such as dust generated upon irradiation with the pulsed laser beam PL is discharged out of the chamber C by a stream of inert gas G _f, thereby preventing adhesion of such swarf and dust into the silicon substrate 1.

In this embodiment, a picosecond to femtosecond pulse laser generator is used as the pulse laser generator PLD, and the p ⁺ type semiconductor region 7 is irradiated with picosecond to femtosecond pulse laser light. The surface (first main surface 1a) of the p ⁺ type semiconductor region 7 is roughened by a picosecond to femtosecond pulse laser beam, and irregular irregularities 11 are formed on the surface of the p ⁺ type semiconductor region 7 as shown in FIG. Formed.

The irregular irregularities 11 have a surface that intersects the direction orthogonal to the second main surface 1b. The height difference of the unevenness 11 is, for example, about 0.5 to 1.0 μm, and the interval between the convex portions in the unevenness 11 is about 0.5 to 1.0 μm. The pulse time width of the picosecond to femtosecond pulse laser beam is, for example, about 50 fs to 2 ps, the intensity is, for example, about 4 to 16 GW, and the pulse energy is, for example, about 200 to 800 μJ / pulse. More generally, the peak intensity is about 3 × 10 ^{11 to} 2.5 × 10 ¹³ (W / cm ² ), and the fluence is about 0.1 to 1.3 (J / cm ² ). FIG. 5 is an SEM image obtained by observing irregular irregularities 11 formed on the surface of the p ⁺ type semiconductor region 7.

Next, the silicon substrate 1 is heat-treated (annealed). Here, the silicon substrate 1 is heated in the range of about 800 to 1000 ° C. for about 0.5 to 1 hour in an atmosphere of N ₂ gas.

Next, the protective layer 13 is formed on the first main surface 1a and the second main surface 1b of the silicon substrate 1 (see FIG. 6). The protective layer 13 is made of, for example, SiO ₂ and is formed by, for example, a plasma CVD method. The thickness of the protective layer 13 is, for example, about 1 μm. The protective layer 13 also functions as an insulating layer. Then, a contact hole H 1 is formed in the protective layer 13 on the p ⁺ type semiconductor region 7, and a contact hole H 2 is formed in the protective layer 13 on the n ⁺ type semiconductor region 9. As shown in FIG. 6, it is preferable that the irregular irregularities 11 formed on the surface of the p ⁺ type semiconductor region 7 are exposed. The irregular irregularities 11 may be optically exposed as will be described later, and may be covered with a protective layer 13 of about 1 μm, for example.

  Next, electrodes 15 and 17 are formed (see FIG. 7). The electrode 15 is formed in the contact hole H1, and the electrode 17 is formed in the contact hole H2. The electrodes 15 and 17 are each made of aluminum (Al) or the like, and have a thickness of about 1 μm, for example. Thereby, the photodiode PD1 is completed.

As shown in FIG. 7, the photodiode PD1 includes a silicon substrate 1. The silicon substrate 1 has an n ⁻ type semiconductor region 3 on the first main surface 1a side and an n ⁺ type semiconductor region 5 on the second main surface 1b side. the n ^- -type semiconductor region 3, p ⁺ -type semiconductor region 7 is provided, n ^- pn junction between the semiconductor region 3 and the p ⁺ -type semiconductor region 7 is formed. The n ⁺ type semiconductor region 9 functions as a guard ring.

The electrode 15 is in electrical contact and connection with the p ⁺ type semiconductor region 7 through the contact hole H1. The electrode 17 is in electrical contact with and connected to the n ⁺ type semiconductor region 9 through the contact hole H2.

Irregular irregularities 11 are formed on the surface of the p ⁺ type semiconductor region 7 (the first main surface 1a of the silicon substrate 1). In this embodiment, irregular irregularities 11 are formed except for the region where the electrode 15 is connected on the surface of the p ⁺ type semiconductor region 7. The surface of the p ⁺ type semiconductor region 7 is optically exposed. p ⁺ -type and the surface of the semiconductor region 7 is optically exposed, the surface of the p ⁺ -type semiconductor region 7 is not only in contact with ambient gas such as air, over the surface of the p ⁺ -type semiconductor region 7 In some cases, an optically transparent film is formed. In the present embodiment, the region where irregular irregularities 11 are formed on the surface of the p ⁺ type semiconductor region 7 is not covered with the protective layer 13 and is exposed. When the protective layer 13 is optically transparent, the protective layer 13 may be formed so as to cover a region where the irregular irregularities 11 are formed on the surface of the p ⁺ type semiconductor region 7. When the protective layer 13 is not optically transparent, the protective layer 13 is formed so as not to cover a region where the irregular irregularities 11 are formed on the surface of the p ⁺ type semiconductor region 7.

As shown in FIG. 8, the photodiode PD1 is arranged such that the second main surface 1b is a light incident surface. When light is incident on the photodiode PD1 from the second main surface 1b side, the long wavelength band light L1 including the near infrared in the incident light travels long in the silicon substrate 1 and the surface of the p ⁺ type semiconductor region 7 To the irregular irregularities 11 formed in

  Usually, the refractive index n of air is 1.0 while the refractive index n of Si is 3.5. In a photodiode, when light is incident from a direction perpendicular to the light incident surface, light that is not absorbed in the photodiode (silicon substrate) passes through the light component reflected by the back surface of the light incident surface and the photodiode. Divided into light components. The light transmitted through the photodiode does not contribute to the sensitivity of the photodiode. The light component reflected by the back surface of the light incident surface is absorbed in the photodiode and becomes a photocurrent.

In the photodiode PD1, when light is incident from a direction perpendicular to the light incident surface (second main surface 1b), long wavelength band light L1 including near infrared is formed on the surface of the p ⁺ type semiconductor region 7. When the irregular asperity 11 is reached, the light component that has arrived at an angle of 16.6 ° or more with respect to the emission direction from the asperity 11 is totally reflected by the asperity 11. Since the irregularities 11 are irregularly formed, they have various angles with respect to the emission direction, and the totally reflected light component diffuses in various directions. Thus, the totally reflected light components, further n ^- Take -type semiconductor region 3, n ^- is absorbed inside -type semiconductor region 3. The light that has not been absorbed then travels through the n ⁺ type semiconductor region 5, and a part of the light is reflected by the surface of the silicon substrate 1 and travels through the silicon substrate 1 for a long time. Light is absorbed also in the n ⁺ type semiconductor region 5, but the light absorbed in the n ⁺ type semiconductor region 5 does not contribute to sensitivity. As described above, the light L1 in the long wavelength band including the near infrared is detected as a photocurrent as it is absorbed by the n ⁻ type semiconductor region 3 while traveling through the silicon substrate 1 for a long distance. Become.

Most of the light L1 in the long wavelength band including near infrared among the light incident on the photodiode PD1 is absorbed by the n ⁻ type semiconductor region 3 without being transmitted through the photodiode PD1 and having a longer traveling distance. Will be. Then, the carriers generated by the light L1 move to the pn junction and are detected as a photocurrent. Therefore, in the photodiode PD1, the spectral sensitivity characteristic in the near-infrared wavelength band is improved.

On the other hand, the light L2 in the short wavelength band out of the light incident on the photodiode PD1 enters the silicon substrate 1 and then travels from the light incident surface (second main surface 1b) without going through the silicon substrate 1 for a long time. Although carriers are generated at a relatively shallow position, since the n ⁺ type semiconductor region 5 exists on the light incident surface (second main surface 1b) side, carriers generated by the light L2 in the short wavelength band are n It is trapped in the ⁺ type semiconductor region 5 and hardly moves to the pn junction. For this reason, the light L2 in the short wavelength band hardly contributes to the light detection sensitivity of the photodiode PD1. The limit on the short wavelength side in the spectral sensitivity characteristic of the photodiode PD ^< b> ¹ can be controlled by the thickness of the n ⁺ type semiconductor region 5.

  From the above, the photodiode PD1 has practically sufficient spectral sensitivity characteristics only in a narrow wavelength band including near infrared.

  Here, in this embodiment, an experiment was conducted to confirm the effect of having a spectral sensitivity characteristic that is practically sufficient only in a narrow wavelength band including the near infrared.

A photodiode (referred to as Example 1) having the above-described configuration was manufactured, and the spectral sensitivity characteristics of each were examined. The size of the silicon substrate 1 was set to 6.5 mm × 6.5 mm. The thicknesses of the n ⁻ type semiconductor region 3 and the n ⁺ type semiconductor region 5 were set to 300 μm and 200 μm, respectively. The size of the p ⁺ type semiconductor region 7, that is, the photosensitive region was set to 5.8 mm × 5.8 mm. The bias voltage VR applied to the photodiode was set to 0V.

As Comparative Example 1, a general photodiode having a p ⁺ type semiconductor region formed on an n ⁻ type semiconductor substrate was employed. The size of the n ⁻ type semiconductor substrate in Comparative Example 1 was set to be equal to the size of the silicon substrate 1 in Example 1 described above, except for the thickness. The thickness of the n ⁻ type semiconductor substrate was set to 1.5 mm. The size of the p ⁺ type semiconductor region in Comparative Example 1 was set to be equal to the size of the p ⁺ type semiconductor region 7 in Example 1 described above.

  The results are shown in FIG. In FIG. 9, the spectral sensitivity characteristic of Example 1 is indicated by a characteristic T1, and the spectral sensitivity characteristic of Comparative Example 1 is indicated by a characteristic T2. In FIG. 9, the vertical axis represents spectral sensitivity (mA / W), and the horizontal axis represents the wavelength (nm) of light. The characteristic indicated by the broken line indicates the spectral sensitivity characteristic at which the quantum efficiency (QE) is 100%.

  As can be seen from FIG. 9, as compared with the photodiode of Comparative Example 1, the photodiode of Example 1 has a spectral sensitivity characteristic sufficient for practical use only in a narrow wavelength band including near infrared (for example, 1100 to 1150 nm). have.

  In a semiconductor photodetection element such as a photodiode, a semiconductor photodetection element having spectral sensitivity characteristics in the near-infrared wavelength band is realized by setting a semiconductor substrate made of silicon thick (for example, about several hundred μm to 2 mm). It is possible. However, it is difficult to realize a semiconductor photodetecting element having practically sufficient spectral sensitivity characteristics in the near-infrared wavelength band as in the first embodiment described above, simply by setting the semiconductor substrate thick.

That is, in the photodiode PD1 according to the present embodiment, as described above, irregular irregularities 11 are formed on the surface of the p ⁺ type semiconductor region 7, so that the near red light out of the light incident on the photodiode PD1. The traveling distance of light in the long wavelength band including the outside becomes longer. For this reason, a photosensor having a spectral sensitivity characteristic practically sufficient in the near-infrared wavelength band without increasing the thickness of the silicon substrate 1 (n ⁻ type semiconductor region 3), particularly the portion corresponding to the pn junction that is the photosensitive region. A diode can be realized. Therefore, by increasing the thickness of the semiconductor substrate, an increase in dark current is suppressed in the photodiode PD1 and the detection accuracy of the photodiode PD1 is improved as compared with the photodiode having spectral sensitivity characteristics in the near-infrared wavelength band. Furthermore, since the thickness of the silicon substrate 1 (n ⁻ type semiconductor region 3) is thin, the response speed of the photodiode PD1 is also improved.

  In this embodiment, the silicon substrate 1 is heat-treated after the irregular irregularities 11 are formed. Thereby, recovery and recrystallization of crystal damage caused in the process of forming irregular irregularities 11 can be achieved, and problems such as increase in dark current can be prevented.

In the present embodiment, the thickness of the p ⁺ type semiconductor region 7 is larger than the height difference of the irregular irregularities 11. Therefore, after forming the p ⁺ -type semiconductor region 7, by irradiating a pulsed laser beam, they are formed irregular asperity 11, so that the p ⁺ -type semiconductor region 7 remains securely. Therefore, the n ⁻ type semiconductor region 3 and the p ⁺ type semiconductor region 7 can surely form a pn junction.

  In the present embodiment, irregular irregularities 11 are formed by irradiation with picosecond to femtosecond pulsed laser light. Thereby, the irregular unevenness | corrugation 11 can be formed appropriately and easily.

  In the present embodiment, the electrodes 15 and 17 are formed after the silicon substrate 1 is heat-treated. Accordingly, even when a material having a relatively low melting point is used for the electrodes 15 and 17, the electrodes 15 and 17 are not melted by the heat treatment, and the electrodes 15 and 17 are appropriately formed without being affected by the heat treatment. be able to.

  The preferred embodiments of the present invention have been described above. However, the present invention is not necessarily limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

For example, the present invention is also applicable to a photodiode array PDA1 in which a plurality of p ⁺ type semiconductor regions 7 are formed as shown in FIG.

  The p-type and n-type conductivity types in the photodiode PD1 and the photodiode array PDA1 according to this embodiment may be interchanged so as to be opposite to those described above.

  The present invention can be used for semiconductor photodetection elements such as photodiodes.

DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 1a ... 1st main surface, 1b ... 2nd main surface, 3 ... n ^- type semiconductor region, 5 ... n ⁺ type semiconductor region, 7 ... p ⁺ type semiconductor region, 11 ... Irregular unevenness | corrugation, 15, 17 ... Electrodes, PD1 ... Photodiode, PDA1 ... Photodiode array, PL ... Pulse laser beam.

Claims (7)

A silicon substrate having a light incident surface on which light to be detected is incident and a back surface facing the light incident surface;
The silicon substrate has a first conductivity type first semiconductor layer on the back surface side, and a first conductivity type second semiconductor layer having an impurity concentration higher than that of the first semiconductor layer on the light incident surface side. Have
On the back side of the first semiconductor layer, a pn junction is formed with the first semiconductor layer, and a second conductivity type third semiconductor region having a higher impurity concentration than the first semiconductor layer is provided,
The surface of the third semiconductor region is optically exposed and irregular irregularities are formed.   The semiconductor photodetecting element according to claim 1, wherein the thickness of the third semiconductor region is larger than the irregular height difference of the irregularities. An electrode that is in electrical contact with and connected to the third semiconductor region is disposed on the back side of the silicon substrate,
3. The semiconductor photodetector according to claim 1, wherein the irregular unevenness is formed except for a region where the electrode is connected to the surface of the third semiconductor region. 4. Impurities having first and second main surfaces opposed to each other, having a first semiconductor layer of a first conductivity type on the first main surface side, and higher than the first semiconductor layer on the second main surface side Providing a silicon substrate having a second semiconductor layer of a first conductivity type having a concentration;
Forming a second conductivity type third semiconductor region having an impurity concentration higher than that of the first semiconductor layer on the back surface side of the first semiconductor layer ;
Irradiating the surface of the third semiconductor region with pulsed laser light to form irregular irregularities;
And a step of heat-treating the silicon substrate on which irregular irregularities are formed. 5. The method of manufacturing a semiconductor photodetecting element according to claim 4 , wherein the thickness of the third semiconductor region is larger than the irregular height difference of the irregularities. Wherein in the step, a method of manufacturing a semiconductor light detecting device according to claim 4 or 5, characterized in that irradiating the picosecond to femtosecond pulsed laser beam as a pulse laser beam to form a disordered said irregularities. Further comprising forming an electrode in electrical contact with and connected to the third semiconductor region on the back side of the silicon substrate;
The said process of forming the said electrode forms an electrode in the area | region in which the said irregular unevenness | corrugation in the said back surface of the said silicon substrate is not formed. Manufacturing method of semiconductor photodetection element.