KR20120077708A - Localized emitter solar cell and method for manufacturing thereof - Google Patents

Abstract

The present invention provides a localized emitter solar cell comprising locally forming an emitter and an electrode on a light receiving surface of a substrate, and forming an auxiliary electrode layer for transferring a small number of carriers collected through the emitter to an electrode between the emitter and the electrode. A manufacturing method comprising the steps of: preparing a substrate of a first conductivity type; Forming a dielectric layer on the surface of the substrate; Forming a rear electrode on the lower surface of the substrate; Forming a highly doped region of a second conductive impurity locally in an upper layer of the substrate; Depositing an auxiliary electrode layer on the substrate; By forming the front electrode on the auxiliary electrode layer, it is possible to increase the lifetime of the minority carriers by reducing the recombination rate of the minority carriers generated in the substrate and collected by the electrode, and the line width, number and spacing of the electrodes, etc. Regardless of the form of the same electrode pattern, there is an effect of maximizing photoelectric conversion efficiency of the solar cell by safely delivering a small number of phototransmitters transported to the electrode in the substrate.

Description

Localized Emitter Solar Cell and Method for Manufacturing Thereof

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a localized emitter solar cell and a method of manufacturing the same, and more particularly, to a localized emitter solar cell in which an emitter and an electrode are locally formed on a light receiving surface of a substrate.

The solar cell is a key element of photovoltaic power generation that converts sunlight directly into electricity, and is basically a diode composed of a p-n junction.

In the process of converting sunlight into electricity by solar cells, solar light is incident on the solar cells to generate electron-hole pairs inside the solar cells, and electrons move to n layers and holes move to p layers by the electric field. Thus, photovoltaic power is generated between the pn junctions, and when a load or a system is connected to both ends of the solar cell, current flows to generate power.

On the other hand, solar cells are classified into various types according to the shape of the light absorption layer or the impurity ions, which are pn junction layers. Examples of the light absorption layer include silicon (Si). The silicon substrate type used as the light absorption layer is divided into a thin film type which forms a light absorption layer by depositing silicon in a thin film form.

Looking at the general structure of the silicon substrate type of silicon-based solar cell as an example.

As illustrated in FIG. 1, a second conductive semiconductor layer 12, which is an emitter layer, is stacked on the first conductive semiconductor layer 11, and a finger bar or the upper surface of the second conductive semiconductor layer 12 is formed. A front electrode 14 having a pattern such as a bus bar is formed and a rear electrode 15 is provided on a lower surface of the first conductive semiconductor layer 11.

In this case, the first conductive semiconductor layer 11 and the second conductive semiconductor layer 12 are implemented on one silicon substrate 10, and the lower portion of the silicon substrate 10 is the first conductive semiconductor layer 11. The upper portion of the silicon substrate 10 is divided into the second conductive semiconductor layer 12, and a lower concentration doped layer of the first conductive impurity for forming a backside electric field is formed below the first conductive semiconductor layer 11. 10-1) and the second conductive semiconductor layer 12 having the front electrode 14 formed on an upper surface thereof, are provided with a highly doped region 10-2 of the second conductive impurity.

Looking at the general manufacturing process of such a substrate-type silicon solar cell, first preparing a silicon substrate 10 of the first conductivity type, surface texturing of the prepared silicon substrate 10, doping impurity ion (Doping) of the second conductivity type The second conductive semiconductor layer 12 may be formed through diffusion, and the front electrode 14 and the rear electrode 15 may be formed.

Meanwhile, before the front electrode 14 and the back electrode 15 are formed, impurities including impurities such as a PSG (Phosphorus Silicate Glass) film or a BSG (Boron Silicate Glass) film formed on the surface of the substrate 10 by a diffusion process are formed. A cleaning process for removing an oxide film and a process for forming an anti-reflection film 13 on the second conductive semiconductor layer 12, and the like, to reduce contact resistance between the surface of the silicon substrate 10 and the front electrode 14. In order to form the second conductive semiconductor layer 12 corresponding to the portion where the front electrode 14 is to be formed, a highly doped region 10-2, that is, an emitter, of the second conductive impurity is selectively formed.

Here, since the highly doped layer 10-1 of the first conductivity type impurity forms a backside electric field having a higher energy barrier than the first conductivity type semiconductor layer 11, the first conductivity type semiconductor layer 11 is later formed. The small number of carriers (1) generated by the solar light incident in the inside serves to block the movement to the rear electrode (15).

In addition, after the formation of the front electrode 14 and the rear electrode 15, a high concentration doping layer 10-1 of the first conductivity type impurity is formed under the first conductivity type semiconductor layer 11 through a firing process. In addition, an insulating process of forming a trench for disconnection of a predetermined depth is performed along the circumference of the front surface of the substrate using a laser.

When the second conductive semiconductor layer 12 is formed, the silicon substrate 10 is immersed in a solution containing the second conductive impurity ions and subsequently subjected to a heat treatment process, thereby forming the second conductive impurity ions into a silicon substrate ( 10), the second conductive semiconductor layer is formed on the side of the substrate in addition to the upper portion of the silicon substrate 10. Thus, the second conductive semiconductor layer formed on the side of the substrate is the front electrode 14; Since the back electrode 15 is shorted to act as a factor of reducing photoelectric conversion efficiency of the solar cell, the front electrode 14 and the rear surface of the second conductive semiconductor layer formed on the side of the silicon substrate 10 are reduced. This is because it is necessary to interrupt the electrical connection between the electrodes 15.

Looking at the movement of the minority transporter (1) during photovoltaic power generation in such a general solar cell, for example, when the first conductivity type is p-type, the second conductivity type is n-type, as the solar light enters the first conductive semiconductor The electrons, which are the minority carriers 1 generated in the layer 11, move toward the front surface of the silicon substrate 10 on which the second conductive semiconductor layer 12, that is, the emitter layer, is formed. At this time, the hole which is the majority carrier 2 is moved toward the rear side of the silicon substrate 10.

In such a general solar cell, the impurity doping concentration in the depth direction is highest at the top and decreases toward the bottom, and accordingly, the conduction band is lowered toward the top in the energy band structure. Since the semiconductor layer 12, that is, the emitter layer, is formed on the entire light-receiving surface of the silicon substrate 10, the minority transport photogenerated in the first conductive semiconductor layer 11 by the depth energy band structure of the emitter layer. The self moves along the emitter layer, and in particular, moves along the surface of the silicon substrate 10 above the emitter layer adjacent to the anti-reflection film 13 and is collected by the front electrode 14.

However, since the surface area of the silicon substrate 10, which is the movement path of the minority transporter 1, is a high density of defects in which a large number of crystal defects and impurities exist, the minority transporter 1 has such a conventional solar cell. There is a fear that it may be easily lost by recombination before being collected by the front electrode 14.

Furthermore, in the conventional solar cell, since the front electrode 14 having a large line width W within a range of 100 µm to 140 µm must be formed on the front surface of the silicon substrate 10, that is, the light receiving surface, it is sufficient to maintain the light receiving rate. In order to secure the light-receiving surface of the area, the distance d between the front electrodes 14 is formed very large within 1800 μm to 2300 μm, so that the minority carriers 1 generated in the first conductive semiconductor layer 11 are silicon. Since the distance to the front electrode 14 along the surface portion of the substrate 10 becomes longer, the minority transporter 1 is recombined and disappeared from the surface of the silicon substrate 10 before it is collected by the front electrode 14. Increase the likelihood.

That is, the conventional solar cell has a problem in that the photoelectric conversion efficiency is low due to its high recombination rate of the minority transporter 1 photogenerated in the silicon substrate 10.

In addition, in the conventional solar cell, when the number of the front electrodes 14 is reduced in order to secure the light receiving surface of the silicon substrate 10, the distance d between the front electrodes 14 becomes larger, so that the silicon substrate 10 is formed. As the minority carrier recombination rate at the surface is further increased, it is difficult to improve the light receiving rate of the solar cell, and thus, there is a problem in that the efficiency of the solar cell is also difficult to increase.

In addition, a conventional solar cell requires a complicated process procedure such as a cleaning process for removing an oxide film and an insulation process for forming a trench for disconnection, and thus, a manufacturing period and a manufacturing cost are high.

The present invention has been made to solve the problems described above, and to form an emitter and an electrode locally on the light receiving surface of the substrate, for transferring a small number of carriers collected through the emitter between the emitter and the electrode to the electrode The present invention provides a localized emitter solar cell in which an auxiliary electrode layer is formed, and a method of manufacturing the same.

A solar cell according to an embodiment of the present invention for achieving the above object, includes a first conductive substrate of a silicon material having a front electrode and a rear electrode on the upper and lower surfaces, the upper layer portion of the substrate The highly doped region of the second conductive impurity is locally formed, and a dielectric layer and an auxiliary electrode layer are sequentially stacked between the substrate and the front electrode.

Here, the dielectric layer is preferably formed at a portion of the upper surface of the substrate except for a portion where the high concentration doped region of the second conductive impurity is exposed.

This dielectric layer is preferably made of silicon oxide, aluminum oxide, titanium oxide or silicon nitride.

In addition, the auxiliary electrode layer may be formed on the dielectric layer to be in direct contact with the doped region of the high concentration dopant of the second conductive impurity, or to contact the plating layer.

The auxiliary electrode layer is preferably made of a transparent conductive oxide film.

As such, the dielectric layer and the auxiliary electrode layer preferably serve as an anti-reflective coating (ARC).

Furthermore, it is preferable that the substrate has a high concentration doping layer of a first conductivity type impurity that forms a rear electric field in the lower layer portion.

In addition, the highly doped region of the second conductive impurity is preferably formed in a line pattern having a regular or irregular line width and spacing.

In addition, the highly doped region of the second conductive impurity is preferably formed in a dot pattern having a regular or irregular size and spacing.

In this case, the front electrode is preferably formed in a direction parallel or perpendicular to the pattern of the high concentration doped region of the second conductive impurity.

On the other hand, the method of manufacturing a localized emitter solar cell according to an embodiment of the present invention comprises the steps of preparing a substrate of the first conductive type; Forming a dielectric layer on the surface of the substrate; Forming a rear electrode on the lower surface of the substrate; Forming a highly doped region of a second conductive impurity locally in an upper layer of the substrate; Depositing an auxiliary electrode layer on the substrate; It is preferable to include forming a front electrode on the auxiliary electrode layer.

The forming of the back electrode may include applying a metal material to a lower surface of the substrate; Forming a back electrode on a lower surface of the substrate by performing a baking process; It is preferable to include the step of forming a high concentration doped layer of the first conductivity type impurities in the lower layer of the substrate by the heat treatment during the baking step.

In the forming of the heavily doped region of the second conductive type impurity, a laser doping process is performed to locally remove the dielectric layer formed on the substrate, and to remove the dielectric layer formed on the upper layer of the substrate from which the dielectric layer is removed. It is preferable to dope the two conductive impurities.

The method of manufacturing a localized emitter solar cell according to the present invention preferably further comprises depositing a seed layer to directly contact the heavily doped region of the second conductive impurity.

According to the localized emitter solar cell according to the present invention and a method of manufacturing the same, while locally forming an emitter and an electrode on the light receiving surface of the substrate, to transfer a small number of carriers collected through the emitter between the emitter and the electrode to the electrode By forming the auxiliary electrode layer, the lifetime of the minority carriers can be increased by reducing the recombination rate of the minority carriers that are generated in the substrate and collected by the electrodes, and can be used regardless of the electrode pattern type such as the line width, number and spacing of the electrodes. In addition, it is possible to maximize the photoelectric conversion efficiency of the solar cell by delivering a small number of phototransmitters transported to the electrode safely in the substrate.

In addition, according to the localized emitter solar cell according to the present invention and a method for manufacturing the same, the maximum light receiving surface of the substrate is secured by reducing the line width and number of electrodes to be formed on the light receiving surface of the substrate and maximizing the distance between the electrodes. It is possible to form an electrode pattern, thereby maximizing the light receiving rate of the solar cell has the effect of increasing the efficiency of the solar cell.

In addition, according to the localized emitter solar cell and the manufacturing method according to the present invention, there is no need to perform the cleaning process for removing the oxide film, the insulation process for forming the trench for disconnection, etc. It can shorten and reduce the manufacturing cost.

1 is a cross-sectional view showing the structure of a typical solar cell.
2 is a plan view of a localized emitter solar cell according to an embodiment of the present invention.
3 is a cross-sectional view of the localized emitter solar cell according to AA ′ in FIG. 2;
Figure 4 is a process flow chart for explaining a manufacturing method of a localized emitter solar cell according to an embodiment of the present invention.
5 to 10 are cross-sectional views illustrating a method of manufacturing a localized emitter solar cell according to an embodiment of the present invention.
11 to 12 are cross-sectional views illustrating a method of manufacturing a localized emitter solar cell according to another embodiment of the present invention.

Hereinafter, a localized emitter solar cell and a method of manufacturing the same according to a preferred embodiment of the present invention with reference to the accompanying drawings will be described in detail.

2 to 3, a localized emitter solar cell according to an embodiment of the present invention is a substrate of a first conductive type of silicon material having a front electrode 14 and a rear electrode 15 at upper and lower portions thereof ( 10, wherein a high concentration doped region 10-2 of the second conductive impurity is locally formed in the upper layer of the substrate 10, and the dielectric layer 20 is formed between the substrate 10 and the front electrode 14. And the auxiliary electrode layers 30 are sequentially stacked. Here, the first conductivity type may be n type or p type, hereinafter, the first conductive type is p type, and the second conductive type is n type.

At this time, the heavily doped region 10-2 of the second conductive type impurity forms a pn junction in the substrate 10, thereby enabling movement of a small number of phototransmitters generated by solar incidence, thereby allowing the inside of the substrate 10 to be moved. A potential difference may be generated and serves to reduce the contact resistance between the metallic front electrode 14 and the interface between the substrate 10.

The high concentration doped region 10-2 of the second conductive type impurity is formed in a dot pattern having a regular size and spacing on the upper layer of the substrate 10 as shown in FIG. As shown in (b) of FIG. 1, the upper layer of the substrate 10 is preferably formed with a line pattern having a regular line width and spacing, but has a dot pattern having an irregular size and spacing, or an irregular line width and spacing. It may also be formed in a line pattern. That is, the heavily doped region 10-2 of the second conductive type impurity may be formed in the upper layer of the substrate 10 in various forms without restriction of the pattern form. However, the highly doped region 10-2 of the second conductive type impurity has a narrow spacing (for example, about 450 μm to 2300 μm) in order to reduce the moving distance of the photo-generated minority transporter in the substrate 10. It is preferably formed to have a suitable width (for example, about 20㎛ to 40㎛).

Meanwhile, the dielectric layer 20 is formed on a portion of the upper surface of the substrate 10 except for the exposed portion of the highly doped region 10-2 of the second conductive impurity.

The dielectric layer 20 may be formed of silicon oxide (SiO ₂ ), aluminum oxide (AlO ₃ ), titanium oxide (TiO ₂ ), silicon nitride (Si ₃ N ₄ ), or the like, and the front passivation of the substrate 10 may be performed. (Passivation) It plays a role.

Meanwhile, the auxiliary electrode layer 30 is formed by being stacked on the dielectric layer 20 so as to directly contact the heavily doped region 10-2 of the second conductive impurity.

The auxiliary electrode layer 30 is photogenerated in the substrate 10, and a few carriers collected through the high concentration doping region 10-2 of the second conductivity type impurity can move to the front electrode 14 by moving. It is composed of a material that provides a migration path, for example, it may be made of a transparent conductive oxide film (TCO).

As described above, the dielectric layer 20 and the auxiliary electrode layer 30 are each formed to have a predetermined thickness in consideration of refractive index, so that an anti-reflection film (ARC) can prevent light reflection loss of the upper surface of the substrate 10, that is, the light receiving surface. -Reflective Coating

On the other hand, the lower layer portion of the substrate 10 is provided with a high concentration doping layer 10-1 of the first conductivity type impurity forming a rear electric field for blocking the rear side movement of the photo-generated minority transporter.

In addition, since the front electrode 14 may trap a small number of carriers through the auxiliary electrode layer 30 stacked on the entire upper surface of the substrate 10, the second conductive type is locally formed on the upper layer of the substrate 10. Since the patterning does not have to correspond to the formation position of the highly doped region 10-2 of the impurity, the upper portion of the auxiliary electrode layer 30 does not correspond to the formation position of the highly doped region 10-2 of the second conductivity type impurity. It can be formed on the side. Of course, if necessary, the front electrode 14 may be formed on the upper surface of the auxiliary electrode layer 30 to correspond to the formation position of the highly doped region 10-2 of the second conductivity type impurity.

For example, the front electrode 14 may be formed in a pattern such as a finger line shape, wherein the front electrode 14 has a narrow line width (W) of about 20 μm to 40 μm, and between electrodes of about 1800 μm to 2300 μm. It is formed to have a distance (d) or, if necessary, is formed to exceed 2300㎛ within a range that does not exceed the light receiving surface of the substrate 10, thereby ensuring a much wider light receiving surface than the light receiving surface of a typical solar cell. have. In addition, the front electrode 14 may be formed in a direction parallel or perpendicular to the pattern of the highly doped region 10-2 of the second conductive impurity.

Hereinafter, a method of manufacturing a localized emitter solar cell according to an embodiment of the present invention will be described with reference to FIGS. 4 to 10.

First, as shown in FIG. 4, a first conductive silicon substrate 10 is prepared (S100).

In step S100, a saw damage etching process of etching the substrate 10 in a chemical manner is performed in order to remove a defective portion generated as a result of the cutting process of the substrate 10. At this time, it is preferable to etch the surface of the substrate 10 by a predetermined depth using a potassium hydroxide (KOH) solution or the like as an etching solution, and then wash using DIW (Deionized Water).

In addition, after the saw damage etching (Saw Damage Etching) process, a wet texturing process or a dry texturing process using an acid or alkaline (Alkaline), etc. are performed. The surface uneven structure of the substrate 10 formed by this texturing process is not shown in FIGS. 5 to 12 for the sake of simplicity.

In the state in which the substrate 10 is prepared through the above step S100, as shown in FIG. 5, the dielectric layers 20 and 21 are formed on the surface of the substrate 10 by performing a heat treatment process (S110).

In the step S110, the dielectric layers 20 and 21 may be made of BSG (Boron Silicate Glass). If the first conductivity type is n-type, it is preferable that the dielectric layers 20 and 21 are made of Phosphorus Silicate Glass (PSG).

Meanwhile, in step S110, the dielectric layer 20 including the silicon nitride film Si ₃ N ₄ is formed only on the upper surface of the substrate 10 by performing a chemical vapor deposition process such as a plasma enhanced chemical vapor deposition (PECVD) process. can do.

After the above step S110, as shown in FIG. 6, a rear metal material 15-1 including aluminum (Al), silver (Ag), and the like is applied to the rear surface of the substrate 10, and the firing process is performed. As shown in FIG. 7, the rear electrode 15 is formed on the lower surface of the substrate 10 (S120).

In the step S120 described above, a high concentration doping layer 10-1 of a first conductive type impurity having aluminum (Al) as a source among the metal materials applied to the lower surface of the substrate 10 is formed by heat treatment during the firing process. It is naturally formed in the lower layer of (10), wherein the dielectric layer 21 formed on the lower surface of the substrate through the above step S110 is the first conductive impurity due to the doping of the first conductive impurity sourced from aluminum (Al). It is preferably included in the high concentration doping layer (10-1).

Subsequently to the step S120, as shown in FIG. 8, the laser doping process is performed to locally remove the dielectric layer 20 formed on the substrate 10 and to remove the dielectric layer 20. 10, the second conductive dopant is doped in the upper layer of the substrate 10, and the high concentration doped region 10-2 of the second conductive dopant is locally exposed in the upper layer of the substrate 10 (S130).

The high concentration doped region 10-2 of the second conductive type impurity formed in the upper layer of the substrate 10 through step S130 may be formed of, for example, a heavy doped n ++ region, and is formed of the substrate 10. It is responsible for forming the electric field from the front.

After the above step S130, as shown in FIG. 9, the auxiliary electrode layer 30 is deposited on the substrate 10 (S140).

The auxiliary electrode layer 30 formed on the substrate 10 through the step S140 is not only deposited on the dielectric layer 20 but also a highly doped region of the second conductive impurity locally exposed in the upper layer of the substrate 10. It is deposited to be in direct contact with (10-2).

After the above step S140, as shown in FIG. 10 by performing a screen printing process, the front electrode 14 in a pattern such as to widen the interval (d) as much as possible to secure the maximum light receiving surface on the auxiliary electrode layer (30) To form (S150).

When the front electrode 14 is formed in step S150, the front metal material including silver (Ag) is coated on the auxiliary electrode layer 30 in a desired pattern, and then the firing process is preferably performed.

The localized emitter solar cell as illustrated in FIGS. 2 to 3 may be manufactured by the above-described steps S100 to S150.

Alternatively, after the step S130 described above, as shown in FIG. 11, the seed layer 20-1, which lowers the specific resistance upon contact with the substrate 10, is formed of a high concentration doped region of the second conductive impurity. After the deposition is performed in direct contact with (10-2), as shown in FIG. 12, by depositing the auxiliary electrode layer 30 on the substrate 10, and performing the above step S150, it is shown in Figure 2 to Localized emitter solar cells as shown in FIG. 3 may be fabricated.

In this case, the auxiliary electrode layer 30 formed on the substrate 10 is also deposited on the dielectric layer 20, but the high concentration doped region 10-2 of the second conductive impurity formed locally exposed on the upper layer of the substrate 10. Is deposited to contact the plating layer 20-1.

The localized emitter solar cell according to the present invention and a method of manufacturing the same are not limited to the above-described embodiment and can be carried out in various modifications within the range allowed by the technical idea of the present invention.

1: minority carrier 2: majority carrier
10: substrate 11: first conductive semiconductor layer
10-1: high concentration doping layer of first conductivity type impurity 12: second conductivity type semiconductor layer
10-2: high concentration doped region of the second conductive type impurity 13: antireflection film
14: front electrode 15: rear electrode
15-1: back metal material 20, 21: dielectric layer
20-1: plating layer 30: auxiliary electrode layer

Claims (14)

It includes a first conductive substrate of a silicon material having a front electrode and a rear electrode on the upper and lower surfaces,
A high concentration doped region of the second conductive impurity is locally formed in the upper layer of the substrate,
A localized emitter solar cell, wherein a dielectric layer and an auxiliary electrode layer are sequentially stacked between the substrate and the front electrode.
The method of claim 1,
The dielectric layer is
The localized emitter solar cell of claim 2, wherein a high concentration doped region of the second conductive impurity is formed in a portion of the upper surface of the substrate except for an exposed portion.
The method of claim 2,
The dielectric layer is
A localized emitter solar cell comprising silicon oxide, aluminum oxide, titanium oxide or silicon nitride.
The method of claim 1,
The auxiliary electrode layer,
The localized emitter solar cell of claim 2, wherein the emitter solar cell is formed on the dielectric layer to be in direct contact with the heavily doped region of the second conductive impurity or to be in contact with the plating layer.
The method of claim 4, wherein
The auxiliary electrode layer,
A localized emitter solar cell comprising a transparent conductive oxide film.
The method according to any one of claims 1 to 5,
The dielectric layer and the auxiliary electrode layer,
Localized emitter solar cell, characterized in that it serves as an anti-reflective coating (ARC).
The method of claim 6,
The substrate,
A localized emitter solar cell comprising a highly doped layer of a first conductivity type impurity that forms a rear electric field in a lower layer portion.
The method of claim 1,
The highly doped region of the second conductive impurity is
A localized emitter solar cell, characterized in that it is formed in a line pattern with regular or irregular line widths and spacing.
The method of claim 1,
The highly doped region of the second conductive impurity is
A localized emitter solar cell, characterized in that it is formed in a dot pattern with regular or irregular size and spacing.
The method according to claim 8 or 9,
The front electrode,
The localized emitter solar cell of claim 2, wherein the emitter is formed in a direction parallel to or perpendicular to the pattern of the heavily doped region of the second conductive impurity.
Preparing a substrate of a first conductivity type;
Forming a dielectric layer on the surface of the substrate;
Forming a rear electrode on the lower surface of the substrate;
Forming a highly doped region of a second conductive impurity locally in an upper layer of the substrate;
Depositing an auxiliary electrode layer on the substrate;
A method of manufacturing a localized emitter solar cell, comprising: forming a front electrode on the auxiliary electrode layer.
The method of claim 11,
Forming the back electrode,
Applying a metal material to the lower surface of the substrate;
Forming a back electrode on a lower surface of the substrate by performing a baking process;
And forming a highly doped layer of a first conductivity type impurity under the substrate by heat treatment during the firing step.
The method of claim 11,
In the step of forming a highly doped region of the second conductivity type impurity,
Localized emitter solar cell manufacturing, characterized in that by performing a laser doping process to locally remove the dielectric layer formed on top of the substrate, and doping the second conductive type impurities in the upper layer of the substrate from which the dielectric layer is removed. Way.
The method according to any one of claims 11 to 13,
And depositing a seed layer to directly contact the heavily doped region of the second conductivity type impurity.

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