JP2013125890A - Photoelectric conversion element and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion element which can improve a passivation effect on a semiconductor substrate.SOLUTION: A photoelectric conversion element 100 comprises: an n-type single crystal silicon substrate 1; an oxide film 2; n-type amorphous films 3, 21-2m-1; an anti-reflection film 4; p-type amorphous films 11-1m; and electrodes 31-3m, 41-4m. The oxide films 2, the n-type amorphous film 3 and the anti-reflection film 4 are sequentially laminated on a surface of the n-type single crystal silicon substrate 1 on a light incident side. The p-type amorphous films 11-1m and the n-type amorphous films 21-2m-1 contact a rear face of the n-type single crystal silicon substrate 1 and alternately arranged in an in-plane direction of the n-type single crystal silicon substrate 1 one by one. The electrodes 31-3m are arranged in contact with the p-type amorphous films 11-1m, respectively and the electrodes 41-4m-1 are arranged in contact with the n-type amorphous films 21-2m-1, respectively.

Description

  The present invention relates to a photoelectric conversion element and a manufacturing method thereof.

  The back contact solar cell has a high efficiency by forming a pn junction and an electrode on the light receiving surface side on the back surface, thereby eliminating shadows from the electrode on the light receiving surface side and absorbing more sunlight. Solar cell to get.

  And in this kind of solar cell, the solar cell which uses a heterojunction as a pn junction is also proposed (patent document 1). In this solar cell, i-type amorphous silicon (a-Si) and n-type a-Si are sequentially laminated on the back surface of the semiconductor substrate, and a part of the laminated i-type a-Si and n-type a-Si is removed. The removed part has a structure in which i-type a-Si and p-type a-Si are sequentially laminated.

In addition, regarding the structure on the light receiving surface side, in addition to a passivation film such as an FSF diffusion layer, silicon nitride (SiN), and silicon dioxide (SiO ₂ ) used in a back contact solar cell that does not use a heterojunction. Thus, a method of passivation with an amorphous silicon film has been proposed (Non-Patent Document 1).

JP 2010-80887 A

23rd EUPVSEC Session Code: 2CV.5.53 (p1749).

  However, when the surface on the light incident side of a single crystal silicon substrate is passivated with an amorphous silicon film as in a conventional solar cell, there is a problem that the effect of passivation on the single crystal silicon substrate is low.

  Therefore, according to the embodiment of the present invention, a photoelectric conversion element capable of improving the effect of passivation to a semiconductor substrate is provided.

  Moreover, according to the embodiment of the present invention, there is provided a method for manufacturing a photoelectric conversion element capable of improving the effect of passivation to a semiconductor substrate.

  According to the embodiment of the present invention, the photoelectric conversion element includes a semiconductor substrate, an oxide film, and first to third amorphous films. The semiconductor substrate is made of single crystal silicon having the first conductivity type. The oxide film is provided in contact with the surface on the light incident side of the semiconductor substrate. The first amorphous film is provided in contact with the oxide film and has the first conductivity type. The second amorphous film is provided on the opposite side of the light incident side surface of the semiconductor substrate and has a second conductivity type opposite to the first conductivity type. The third amorphous film is provided adjacent to the second amorphous film in the in-plane direction of the semiconductor substrate, on the opposite side of the light incident surface of the semiconductor substrate, and has the first conductivity type.

  According to the embodiment of the present invention, in the method for manufacturing a photoelectric conversion element, the oxide film is formed in contact with the light incident surface of the semiconductor substrate made of single crystal silicon having the first conductivity type. After the first step, after the first step, the second step of depositing the first amorphous film having the first conductivity type in contact with the oxide film, and after the first step, the light of the semiconductor substrate A third step of depositing a second amorphous film having a second conductivity type opposite to the first conductivity type on the side opposite to the surface on the incident side; and a second step in the in-plane direction of the semiconductor substrate. And a fourth step of depositing a third amorphous film having the first conductivity type on the opposite side of the light incident side surface of the semiconductor substrate adjacent to the crystalline film.

  In the photoelectric conversion element according to the embodiment of the present invention, the oxide film is provided in contact with the light incident side surface of the semiconductor substrate, and the first amorphous film is provided in contact with the oxide film. As a result, carriers (electrons and holes) existing near the surface on the light incident side of the semiconductor substrate cause the passivation effect of the semiconductor substrate by the oxide film and the FSF effect (surface field effect) by the first amorphous film. Suppresses recombination.

  Therefore, the effect of passivation on the semiconductor substrate can be improved.

  In the method of manufacturing a photoelectric conversion element according to the embodiment of the present invention, the oxide film is provided in contact with the light incident side surface of the semiconductor substrate, and the first amorphous film is provided in contact with the oxide film. . As a result, recombination of the carriers (electrons and holes) existing near the light incident surface of the semiconductor substrate is suppressed as described above.

  Therefore, the effect of passivation on the semiconductor substrate can be improved.

  Furthermore, in the method for manufacturing a photoelectric conversion element according to the embodiment of the present invention, first, an oxide film is provided in contact with the light incident side surface of the semiconductor substrate, and then the first to third amorphous films are formed. Is formed.

  Therefore, the surface on the light incident side of the semiconductor substrate can be protected in the manufacturing process of the photoelectric conversion element.

It is sectional drawing which shows the structure of the photoelectric conversion element by Embodiment 1 of this invention. It is a 1st process drawing which shows the manufacturing method of the photoelectric conversion element shown in FIG. It is a 2nd process figure which shows the manufacturing method of the photoelectric conversion element shown in FIG. FIG. 4 is a third process diagram illustrating a method for manufacturing the photoelectric conversion element illustrated in FIG. 1. FIG. 5 is a cross-sectional view showing a configuration of another photoelectric conversion element according to Embodiment 1. FIG. 6 is a cross-sectional view illustrating a configuration of still another photoelectric conversion element according to Embodiment 1. FIG. 6 is a cross-sectional view illustrating a configuration of still another photoelectric conversion element according to Embodiment 1. 6 is a cross-sectional view illustrating a configuration of a photoelectric conversion element according to Embodiment 2. FIG. It is sectional drawing which shows the structure of the other photoelectric conversion element by Embodiment 2. FIG. FIG. 6 is a cross-sectional view showing a configuration of still another photoelectric conversion element according to Embodiment 2. FIG. 6 is a cross-sectional view showing a configuration of still another photoelectric conversion element according to Embodiment 2.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  In this specification, the “amorphous phase” refers to a state in which silicon (Si) atoms and the like are randomly arranged. Moreover, although amorphous silicon is described as “a-Si”, this notation actually means that hydrogen (H) atoms are included. Amorphous silicon carbide (a-SiC), amorphous silicon oxide (a-SiO), amorphous silicon nitride (a-SiN), amorphous silicon carbon nitride (a-SiCN), amorphous silicon germanium (a-SiGe) and amorphous germanium Similarly, (a-Ge) means that an H atom is contained.

[Embodiment 1]
1 is a cross-sectional view showing a configuration of a photoelectric conversion element according to Embodiment 1 of the present invention. Referring to FIG. 1, a photoelectric conversion element 100 according to Embodiment 1 of the present invention includes an n-type single crystal silicon substrate 1, an oxide film 2, and n-type amorphous films 3, 21 to 2m-1 (m Is an integer of 2 or more), an antireflection film 4, p-type amorphous films 11 to 1m, and electrodes 31 to 3m and 41 to 4m-1.

  The n-type single crystal silicon substrate 1 has, for example, a (100) plane orientation and a specific resistance of 0.1 to 1.0 Ω · cm. The n-type single crystal silicon substrate 1 has a thickness of 100 to 300 μm, for example, and preferably has a thickness of 100 to 200 μm. The n-type single crystal silicon substrate 1 has a textured surface on the light incident side.

The oxide film 2 is made of silicon dioxide (SiO ₂ ), and is provided in contact with the light incident side surface of the n-type single crystal silicon substrate 1. The oxide film 2 has a film thickness of several nm, for example.

The n-type amorphous film 3 is made of an amorphous phase, for example, n-type a-Si. The n-type amorphous film 3 has a thickness of 10 nm to several tens of nm, for example. Furthermore, the phosphorus (P) concentration of the n-type amorphous layer 3 is 1 × 10 ¹⁸ cm ⁻³ to 1 × 10 ²⁰ cm ⁻³ . The n-type amorphous film 3 is formed in contact with the oxide film 2.

The antireflection film 4 is made of, for example, silicon nitride (Si ₃ N ₄ ) and has a film thickness of, for example, 100 nm. The antireflection film 4 is provided in contact with the n-type amorphous film 3.

Each of p-type amorphous films 11 to 1 m is made of an amorphous phase, and is provided in contact with the surface of n-type single crystal silicon substrate 1 opposite to the light incident side. Each of the p-type amorphous films 11 to 1m is made of, for example, p-type a-Si and has a film thickness of, for example, 10 nm. The p-type amorphous films 11 to 1 m are arranged at a desired interval in the in-plane direction of the n-type single crystal silicon substrate 1. Furthermore, the boron (B) concentration in each of the p-type amorphous films 11 to 1 m is, for example, 5 × 10 ¹⁹ cm ⁻³ .

  Each of the n-type amorphous films 21 to 2m-1 is made of an amorphous phase. The n-type amorphous film 21 is disposed in contact with the p-type amorphous films 11 and 12 and the n-type single crystal silicon substrate 1, and the n-type amorphous film 22 is formed of the p-type amorphous films 12 and 13. In the same manner, the n-type amorphous film 2m-1 is divided into the p-type amorphous films 1m-1, 1m and the n-type single crystal silicon substrate 1 in the following manner. It is arranged in contact with.

Each of the n-type amorphous films 21 to 2m−1 is made of, for example, n-type a-Si, and has a film thickness of, for example, 10 nm. Further, the P concentration in each of the n-type amorphous films 21 to 2m−1 is, for example, 5 × 10 ¹⁹ cm ⁻³ .

  The electrodes 31 to 3m are provided in contact with the p-type amorphous films 11 to 1m, respectively. The electrodes 41 to 4m−1 are provided in contact with the n-type amorphous films 21 to 2m−1, respectively. And each of the electrodes 31-3m and 41-4m-1 consists of silver (Ag), for example.

  The p-type amorphous films 11-1m and the n-type amorphous films 21-2m-1 have the same length in the direction perpendicular to the paper surface of FIG. The area occupation ratio, which is the ratio of the entire area of the p-type amorphous film 11 to 1 m to the area of the n-type single crystal silicon substrate 1, is 60 to 93%. The area occupation ratio, which is the ratio of the entire area of 2m−1 to the area of the n-type single crystal silicon substrate 1, is 5 to 20%.

  As described above, the area occupancy of the p-type amorphous films 11 to 1m is made larger than the area occupancy of the n-type amorphous films 21 to 2m-1 by photoexcitation in the n-type single crystal silicon substrate 1. The separated electrons and holes are easily separated by the pn junction (p-type amorphous film 11 to 1 m / n-type single crystal silicon substrate 1), and the contribution ratio of photoexcited electrons and holes to power generation is increased. Because.

  2-4 is a 1st-3rd process drawing which respectively shows the manufacturing method of the photoelectric conversion element 100 shown in FIG.

  A method for manufacturing the photoelectric conversion element 100 will be described. The photoelectric conversion element 100 is manufactured by a plasma CVD method mainly using a plasma apparatus.

  The plasma apparatus includes a preparation chamber, reaction chambers CB1 to CB3, an extraction chamber, a matching unit, and an RF power source. The charging chamber, the reaction chambers CB1 to CB3, and the take-out chamber are arranged in series. A partition valve is used to partition between the charging chamber and the reaction chamber CB1, between the reaction chamber CB1 and the reaction chamber CB2, between the reaction chamber CB2 and the reaction chamber CB3, and between the reaction chamber CB3 and the take-out chamber. It has been. Further, the plasma apparatus is provided with a transport mechanism for sequentially transporting the single crystal silicon substrate from the preparation chamber to the reaction chamber CB1, the reaction chamber CB2, the reaction chamber CB3, and the take-out chamber.

The charging chamber includes a heating mechanism and an exhaust mechanism. The heating mechanism raises the temperature of the single crystal silicon substrate to a predetermined temperature. The exhaust mechanism exhausts the gas in the preparation chamber, and sets the ultimate pressure in the preparation chamber to, for example, 1 × 10 ⁻⁵ Pa or less.

Each of the reaction chambers CB1 to CB3 includes a parallel plate electrode, a heating mechanism, and an exhaust mechanism. The heating mechanism raises the temperature of the single crystal silicon substrate to a predetermined temperature. The exhaust mechanism exhausts the gases in the reaction chambers CB1 to CB3, and sets the ultimate pressure in the reaction chambers CB1 to CB3 to, for example, 1 × 10 ⁻⁵ Pa or less. The parallel plate electrodes are connected to an RF power source through a matching unit. The reaction chamber CB1 is a reaction chamber for depositing p-type a-Si, the reaction chamber CB2 is a reaction chamber for depositing n-type a-Si, and the reaction chamber CB3 is an i-type a A reaction chamber for depositing Si.

The take-out chamber includes an exhaust mechanism. The exhaust mechanism exhausts the gas in the extraction chamber and sets the ultimate pressure in the extraction chamber to, for example, 1 × 10 ⁻⁵ Pa or less.

  Each exhaust mechanism of the charging chamber, the reaction chambers CB1 to CB3, and the take-out chamber includes a turbo molecular pump, a mechanical booster pump, and a rotary pump. The turbo molecular pump, the mechanical booster pump and the rotary pump are serially connected to the charging chamber, the reaction chambers CB1 to CB3 and the extraction chamber, respectively, so that the turbo molecular pump is closest to the charging chamber, the reaction chambers CB1 to CB3 and the extraction chamber. It is connected to. Each exhaust mechanism exhausts the gas in the charging chamber, reaction chambers CB1 to CB3, and the extraction chamber with a turbo molecular pump, a mechanical booster pump, and a rotary pump, respectively, or is charged with a mechanical booster pump and a rotary pump, respectively. The gases in the chamber, reaction chambers CB1 to CB3 and the extraction chamber are exhausted.

  The RF power source applies, for example, RF power of 13.56 MHz to the parallel plate electrodes of the reaction chambers CB1 to CB3 via the matching unit.

  When the manufacture of the photoelectric conversion element 100 is started, the n-type single crystal silicon substrate 1 is ultrasonically cleaned with ethanol or the like and degreased (see step (a) in FIG. 2). Is chemically anisotropically etched using an alkali to texture the surface of the n-type single crystal silicon substrate 1 (see step (b) in FIG. 2).

  Thereafter, the n-type single crystal silicon substrate 1 is immersed in hydrofluoric acid to remove the natural oxide film formed on the surface of the n-type single crystal silicon substrate 1, and the surface of the n-type single crystal silicon substrate 1 is hydrogenated. Terminate.

When the cleaning of the n-type single crystal silicon substrate 1 is completed, the n-type single crystal silicon substrate 1 is put in an oxidation furnace, and the n-type single crystal silicon substrate 1 is thermally oxidized at a temperature of 1000 ° C. in an oxygen atmosphere. In this case, the oxidation time is several minutes, for example. Then, SiO ₂ formed on one surface and end face of n-type single crystal silicon substrate 1 is removed by hydrofluoric acid, and oxide film 2 made of SiO _{2 is} formed on the textured surface of n-type single crystal silicon substrate 1. (See step (c) in FIG. 2).

  Then, the n-type single crystal silicon substrate 1 / oxide film 2 is placed on the substrate holder in the preparation chamber of the plasma apparatus.

After that, the evacuation mechanism in the preparation chamber exhausts the gas in the preparation chamber to 1 × 10 ⁻⁵ Pa or less, and the heating mechanism in the preparation chamber sets the temperature of the n-type single crystal silicon substrate 1 / oxide film 2 to 200 ° C. Heat the substrate holder so that it does. Further, the heating mechanism of the reaction chambers CB1 to CB3 also heats the substrate holder so that the temperature of the n-type single crystal silicon substrate 1 / oxide film 2 is set to 200.degree.

  When the temperature of the n-type single crystal silicon substrate 1 / oxide film 2 reaches 200 ° C., the partition valve between the charging chamber and the reaction chamber CB1 is opened, and the n-type single crystal silicon substrate 1 / oxide film 2 is charged It is conveyed from the chamber to the reaction chamber CB1.

  Table 1 shows the flow rate of the material gas when forming the p-type amorphous films 11 to 1m and the n-type amorphous films 3 and 21 to 2m-1.

When the n-type single crystal silicon substrate 1 / oxide film 2 is transferred to the reaction chamber CB1, 2 sccm of silane (SiH ₄ ) gas, 42 sccm of hydrogen (H ₂ ) gas, and hydrogen diluted 12 sccm of diborane (B ₂ H ₆ ) gas is allowed to flow into the reaction chamber CB1, and the pressure in the reaction chamber CB1 is set in the range of 13.3 Pa to 665 Pa. The RF power source applies RF power in the range of 16 to 80 mW / cm ² to the parallel plate electrodes through the matching unit. As a result, plasma is generated in the reaction chamber CB1, and the p-type amorphous film 20 made of p-type a-Si is formed on the back surface of the n-type single crystal silicon substrate 1 (= the side opposite to the surface on which the oxide film 2 is formed). (See step (d) in FIG. 2). The concentration of B ₂ H ₆ gas diluted with hydrogen is 0.1%.

When the thickness of the p-type amorphous film 20 reaches 10 nm, the application of RF power to the parallel plate electrodes in the reaction chamber CB1 is stopped, and the reaction chamber CB1 of SiH ₄ gas, H ₂ gas, and B ₂ H ₆ gas is stopped. And the reaction chamber CB1 is evacuated to 1 × 10 ⁻⁵ Pa or less by an exhaust mechanism. Then, the gate valve is opened, and the p-type amorphous film 20 / n-type single crystal silicon substrate 1 / oxide film 2 is transferred from the reaction chamber CB1 to the take-out chamber, and the p-type amorphous film 20 / n-type single crystal silicon is transferred. The substrate 1 / oxide film 2 is cooled to room temperature and then taken out.

  Then, a resist is applied to the entire surface of the p-type amorphous film 20 of the extracted p-type amorphous film 20 / n-type single crystal silicon substrate 1 / oxide film 2, and the applied resist is patterned by photolithography. Then, a resist pattern 30 is formed (see step (e) in FIG. 2).

  Thereafter, the p-type amorphous film 20 is etched by dry etching or wet etching using the resist pattern 30 as a mask to form p-type amorphous films 11 to 1m (see step (f) in FIG. 3).

  When the p-type amorphous films 11 to 1m are formed, the p-type amorphous films 11 to 1m / n-type single crystal silicon substrate 1 / the oxide film 2 on the p-type amorphous films 11 to 1m side are cleaned with hydrofluoric acid. Then, the p-type amorphous films 11 to 1 m / n-type single crystal silicon substrate 1 / oxide film 2 are arranged on the substrate holder in the preparation chamber of the plasma apparatus.

And the exhaust mechanism of the preparation chamber exhausts the gas in the preparation chamber to 1 × 10 ⁻⁵ Pa or less, and the heating mechanism of the preparation chamber is the p-type amorphous film 11 to 1 m / n type single crystal silicon substrate 1 / The substrate holder is heated so that the temperature of the oxide film 2 is set to 200.degree.

  When the temperature of the p-type amorphous film 11 to 1 m / n type single crystal silicon substrate 1 / oxide film 2 reaches 200 ° C., the p-type amorphous film 11 to 1 m / n type single crystal silicon substrate 1 / oxide film 2 is transferred from the preparation chamber to the reaction chamber CB2.

When the p-type amorphous film 11 to 1 m / n-type single crystal silicon substrate 1 / oxide film 2 is transferred to the reaction chamber CB2, 20 sccm of SiH ₄ gas, 150 sccm of H ₂ gas, and 50 sccm diluted with hydrogen are used. Phosphine (PH ₃ ) gas is allowed to flow into the reaction chamber CB2 (see Table 1), and the pressure in the reaction chamber CB2 is set in the range of 13.3 Pa to 665 Pa. The RF power source applies RF power in the range of 16 to 80 mW / cm ² to the parallel plate electrodes through the matching unit. As a result, plasma is generated in the reaction chamber CB2, and an n-type amorphous film 40 made of n-type a-Si is deposited on the surfaces of the p-type amorphous films 11 to 1m and the n-type single crystal silicon substrate 1. (See step (g) in FIG. 3). The concentration of PH ₃ gas diluted with hydrogen is 0.2%.

When the thickness of the n-type amorphous film 40 reaches 10 nm, the application of RF power to the parallel plate electrodes in the reaction chamber CB2 is stopped, and SiH ₄ gas, H ₂ gas, and PH ₃ gas are supplied to the reaction chamber CB2. Supply is stopped and the reaction chamber CB2 is evacuated to 1 × 10 ⁻⁵ Pa or less by an exhaust mechanism. Then, the gate valve is opened, and the n-type amorphous film 40 / p-type amorphous film 11-1m / n-type single crystal silicon substrate 1 / oxide film 2 is transferred from the reaction chamber CB2 to the take-out chamber. Then, the n-type amorphous film 40 / p-type amorphous film 11 to 1m / n-type single crystal silicon substrate 1 / oxide film 2 is cooled to room temperature and taken out from the take-out chamber.

  Thereafter, a resist is applied on the n-type amorphous film 40 / p-type amorphous film 11-1m / n-type single crystal silicon substrate 1 / n-type amorphous film 40 of the oxide film 2, and the applied resist Is patterned by photolithography to form a resist pattern 50 (see step (h) in FIG. 3).

  Thereafter, the n-type amorphous film 40 is etched by dry etching or wet etching using the resist pattern 50 as a mask to form n-type amorphous films 21 to 2m−1 (see step (i) in FIG. 3).

  Then, the n-type amorphous films 21-2m-1 / p-type amorphous films 11-1m / n-type single crystal silicon substrate 1 / oxide film 2 are washed with hydrofluoric acid, The 2m-1 / p-type amorphous film 11 to 1m / n-type single crystal silicon substrate 1 / oxide film 2 are arranged on the substrate holder in the preparation chamber of the plasma apparatus. Although the oxide film 2 is etched by hydrofluoric acid, the oxide film 2 can be cleaned without etching the oxide film 2 by reducing the concentration of hydrofluoric acid.

Then, the exhaust mechanism of the preparation chamber exhausts the gas in the preparation chamber to 1 × 10 ⁻⁵ Pa or less, and the heating mechanism of the preparation chamber is the n-type amorphous film 21-2m−1 / p-type amorphous film. The substrate holder is heated so that the temperature of the 11-1 m / n type single crystal silicon substrate 1 / oxide film 2 is set to 200.degree.

  When the temperature of n-type amorphous film 21-2m-1 / p-type amorphous film 11-1m / n-type single crystal silicon substrate 1 / oxide film 2 reaches 200 ° C., n-type amorphous film 21-1-2 2m-1 / p type amorphous film 11-1m / n type single crystal silicon substrate 1 / oxide film 2 is transferred from the preparation chamber to reaction chamber CB2.

When n-type amorphous film 21-2m-1 / p-type amorphous film 11-1m / n-type single crystal silicon substrate 1 / oxide film 2 is transferred to reaction chamber CB2, 20 sccm of SiH ₄ gas, A 150 sccm H ₂ gas and a hydrogen-diluted 50 sccm PH ₃ gas are allowed to flow into the reaction chamber CB 2 (see Table 1), and the pressure in the reaction chamber CB 2 is set to a range of 13.3 Pa to 665 Pa. The RF power source applies RF power in the range of 16 to 80 mW / cm ² to the parallel plate electrodes through the matching unit. As a result, plasma is generated in the reaction chamber CB2, and an n-type amorphous film 3 made of n-type a-Si is deposited on the oxide film 2 (see step (j) in FIG. 4).

When the thickness of the n-type amorphous film 3 becomes 10 nm to several tens of nm, the application of RF power to the parallel plate electrode of the reaction chamber CB2 is stopped and the reaction of SiH ₄ gas, H ₂ gas and PH ₃ gas is stopped. The supply to the chamber CB2 is stopped, and the reaction chamber CB2 is evacuated to 1 × 10 ⁻⁵ Pa or less by an exhaust mechanism. Then, the gate valve is opened, and the n-type amorphous film 21-2m-1 / p-type amorphous film 11-1m / n-type single crystal silicon substrate 1 / oxide film 2 / n-type amorphous film 3 reacts. It is transferred from the room CB2 to the take-out room. Then, the n-type amorphous film 21-2m-1 / p-type amorphous film 11-1m / n-type single crystal silicon substrate 1 / oxide film 2 / n-type amorphous film 3 is cooled to room temperature and taken out. Remove from room.

Thereafter, n-type amorphous film 21-2m-1 / p-type amorphous film 11-1m / n-type single crystal silicon substrate 1 / oxide film 2 / n-type amorphous film 3 n-type amorphous film An antireflection film 4 made of Si ₃ N ₄ is formed on the substrate 3 by sputtering (see step (k) in FIG. 4).

  Subsequently, Ag is vapor-deposited on the n-type amorphous films 21 to 2m-1 and the p-type amorphous films 11 to 1m side, and the deposited Ag is patterned by photolithography and etching to form electrodes 31 to 3m, 41-4m-1. Thus, the photoelectric conversion element 100 is completed (see step (l) in FIG. 4).

  In the manufacturing method of the photoelectric conversion element 100, the oxide film 2 may be formed by a chemical vapor deposition (CVD) method in the step (c) of FIG. 2, and the oxide film 2 may be formed by oxidation using an oxidizing solution. The oxide film 2 may be formed by an underwater oxidation method that is immersed in water at room temperature or immersed in boiling water, or the oxide film 2 may be formed by a natural oxidation method. When the oxide film 2 is formed by a natural oxidation method, that is, when the oxide film 2 is made of a natural oxide film, after texturing one surface of the n-type single crystal silicon substrate 1, the textured surface is removed. The n-type single crystal silicon substrate 1 is washed with hydrofluoric acid, and then the steps (d) to (l) are sequentially performed.

  Moreover, in the manufacturing method of the photoelectric conversion element 100, after forming the oxide film 2, the n-type amorphous films 3, 21 to 2m-1, the p-type amorphous films 11 to 1m, the antireflection film 4 and the electrodes The order of forming 31 to 3m and 41 to 4m-1 is not limited to the order described in the above-described step (a) to step (l), and may be any order.

  In the photoelectric conversion element 100, when sunlight is irradiated to the photoelectric conversion element 100 from the antireflection film 4 side, electrons and holes are photoexcited in the n-type single crystal silicon substrate 1.

  Even though the photoexcited electrons and holes diffuse to the oxide film 2 side, the passivation effect of the n-type single crystal silicon substrate 1 by the oxide film 2 and the FSF effect (surface electric field effect) by the n-type amorphous film 3 It becomes difficult to recombine, and it becomes easy to diffuse to the p-type amorphous films 11-1m and the n-type amorphous films 21-2m-1 side.

More specifically, since the oxide film 2 (= SiO ₂ ) is in contact with the textured surface of the n-type single crystal silicon substrate 1, the n-type single crystal silicon substrate 1 and the oxide film 2 (= SiO ₂ ) The interface state density at the interface is very low, 10 ¹⁰ cm ⁻² to 10 ¹¹ cm ⁻² . As a result, carriers (electrons and holes) hardly recombine on the textured surface of the n-type single crystal silicon substrate 1. Since the thickness of the oxide film 2 is several nm as described above, carriers (electrons and holes) are separated from the n-type single crystal silicon substrate 1 and the oxide film by the FSF effect of the n-type amorphous film 3. It becomes difficult to reach the interface with 2, and recombination is further suppressed. In particular, recombination of holes that are minority carriers is suppressed. That is, the optical band gap (= about 1.7 eV) and activation energy (= about 0.2 eV to 0.3 eV) of n-type a-Si constituting the n-type amorphous film 3 and the n-type single crystal silicon substrate When the optical band gap (= 1.1 eV) and activation energy (= 0.1 eV to 0.2 eV) of 1 are considered, the end of the valence band of n-type a-Si is the n-type single crystal silicon substrate 1 The n-type amorphous film 3 generates a surface electric field in the vicinity of the surface of the n-type single crystal silicon substrate 1 because it exists on the higher energy side by 0.4 eV to 0.6 eV than the end of the valence band. . As a result, the holes diffused near the surface of the n-type single crystal silicon substrate 1 are difficult to reach the interface between the n-type single crystal silicon substrate 1 and the oxide film 2 due to the surface electric field generated by the n-type amorphous film 3. . Accordingly, recombination of holes that are minority carriers is suppressed by the FSF effect.

  Thus, carriers (electrons and holes) are suppressed from recombination on the surface of the n-type single crystal silicon substrate 1 by the oxide film 2 and the n-type amorphous film 3, and the p-type amorphous films 11 to 1 m. And it becomes easy to diffuse to the n-type amorphous films 21-2m-1.

  Then, the electrons and holes diffused toward the p-type amorphous films 11 to 1m and the n-type amorphous films 21 to 2m-1 are transferred to the p-type amorphous films 11 to 1m / n-type single crystal silicon substrate 1. (= Pn junction) is separated by an internal electric field, holes reach the electrodes 31 to 3 m via the p-type amorphous films 11 to 1 m, and electrons are n-type amorphous films 21 to 2 m−1. To reach the electrodes 41-4m-1.

  The electrons that have reached the electrodes 41 to 4m-1 reach the electrodes 31 to 3m via a load connected between the electrodes 31 to 3m and the electrodes 41 to 4m-1, and recombine with the holes.

  In this manner, the photoelectric conversion element 100 converts the electrons and holes photoexcited in the n-type single crystal silicon substrate 1 into the back surface of the n-type single crystal silicon substrate 1 (= n-type single crystal silicon on which the oxide film 2 is formed). This is a back contact type photoelectric conversion element taken out from the surface opposite to the surface of the substrate 1.

  Further, since the photoelectric conversion element 100 includes the oxide film 2 and the n-type amorphous film 3 on the light incident side, as described above, the carrier is regenerated on the surface of the n-type single crystal silicon substrate 1 on the light incident side. Coupling is suppressed and the passivation effect on the n-type single crystal silicon substrate 1 can be improved.

  In addition, as described in the method for manufacturing the photoelectric conversion element 100, after forming the oxide film 2, the p-type amorphous films 11 to 1m, the n-type amorphous films 3, 21 to 2m-1, and the antireflection film 4 and electrodes 31 to 3m, 41 to 4m-1 (see step (d) in FIG. 2 to step (k) in FIG. 4), in the manufacturing process of the photoelectric conversion element 100, an n-type single crystal silicon substrate The surface on the light receiving surface side of 1 can be protected.

  FIG. 5 is a cross-sectional view showing the configuration of another photoelectric conversion element according to the first embodiment. The photoelectric conversion element according to Embodiment 1 may be a photoelectric conversion element 100A illustrated in FIG.

  Referring to FIG. 5, the photoelectric conversion element 100 </ b> A is obtained by adding i-type amorphous films 51 to 5 m to the photoelectric conversion element 100 illustrated in FIG. 1, and is otherwise the same as the photoelectric conversion element 100.

  The i-type amorphous films 51 to 5m are made of an amorphous phase and are in contact with the n-type single crystal silicon substrate 1 and the p-type amorphous films 11 to 1m, respectively. It arrange | positions between the amorphous | non-crystalline films 11-1m. Each of the i-type amorphous films 51 to 5m is made of, for example, i-type a-Si, and has a film thickness of, for example, 10 nm. In addition, the i-type amorphous films 51 to 5m have the same width as the p-type amorphous films 11 to 1m in the in-plane direction of the n-type single crystal silicon substrate 1 (the left-right direction in the drawing of FIG. 5), respectively. Have. Further, the i-type amorphous films 51 to 5m have the same length as the p-type amorphous films 11 to 1m, respectively, in the direction perpendicular to the paper surface of FIG.

  In the photoelectric conversion element 100A, the thicknesses of the n-type amorphous films 21 to 2m−1 are the thicknesses of the p-type amorphous films 11 to 1m and the i-type amorphous films 61 to 6m. And the total film thickness.

  In the photoelectric conversion element 100A, the end surface of the i-type amorphous film 51 is in contact with the n-type amorphous film 21, and the end surface of the i-type amorphous film 52 is the n-type amorphous film 21, 22. The end surface of the i-type amorphous film 53 is in contact with the n-type amorphous films 22 and 23. Similarly, the end surface of the i-type amorphous film 5m-1 is the n-type amorphous film. The end surfaces of the i-type amorphous film 5m are in contact with the n-type amorphous film 2m-1 in contact with the films 2m-2 and 2m-1.

  100 A of photoelectric conversion elements are manufactured by the process (a)-process (l) shown in FIGS. In this case, in step (d) of FIG. 2, an i-type amorphous film for the i-type amorphous films 51 to 5m is deposited on the n-type single crystal silicon substrate 1 by the plasma CVD method, and then the p-type is formed. A p-type amorphous film 20 for the amorphous films 11 to 1m is deposited on the i-type amorphous film for the i-type amorphous films 51 to 5m by plasma CVD. The gas flow rate when depositing the i-type amorphous films for the i-type amorphous films 51 to 5 m is as shown in Table 1. The pressure and RF power when depositing the i-type amorphous film for the i-type amorphous film 51-5m are p-type amorphous film 11-1m and n-type amorphous film 21-2m- The pressure and RF power when forming 1 are the same.

  The power generation mechanism in the photoelectric conversion element 100A is substantially the same as the power generation mechanism in the photoelectric conversion element 100. As described in the photoelectric conversion element 100, electrons and holes are on the light incident side of the n-type single crystal silicon substrate 1. Recombination on the surface (textured surface) is suppressed, and diffusion to the p-type amorphous films 11-1m and n-type amorphous films 21-2m-1 side is facilitated. Then, the electrons and holes diffused toward the p-type amorphous film 11 to 1 m and the n-type amorphous film 21 to 2 m−1 side are converted into the p-type amorphous film 11 to 1 m / i-type amorphous film 51. ~ 5 m / n type single crystal silicon substrate 1 (= pin junction) is separated by an internal electric field, and holes are separated by electrodes 31 via i-type amorphous films 51 to 5 m and p-type amorphous films 11 to 1 m. To 3m, and the electrons reach the electrodes 41 to 4m-1 through the n-type amorphous films 21 to 2m-1.

  The electrons that have reached the electrodes 41 to 4m-1 reach the electrodes 31 to 3m via a load connected between the electrodes 31 to 3m and the electrodes 41 to 4m-1, and recombine with the holes.

  As described above, the photoelectric conversion element 100 </ b> A converts the electrons and holes photoexcited in the n-type single crystal silicon substrate 1 into the back surface of the n-type single crystal silicon substrate 1 (= n-type single crystal silicon on which the oxide film 2 is formed). This is a back contact type photoelectric conversion element taken out from the surface opposite to the surface of the substrate 1.

  The photoelectric conversion element 100A includes an oxide film 2 provided in contact with the light incident surface (textured surface) of the n-type single crystal silicon substrate 1, and an n-type provided in contact with the oxide film 2. Since the amorphous film 3 is provided, the passivation effect on the n-type single crystal silicon substrate 1 can be improved as described in the photoelectric conversion element 100.

  In the photoelectric conversion element 100A, since the i-type amorphous films 51 to 5m exist between the n-type single crystal silicon substrate 1 and the p-type amorphous films 11 to 1m, the n-type single crystal silicon substrate Recombination of holes at the interface between 1 and the p-type amorphous films 11 to 1 m is suppressed. As a result, the short-circuit photocurrent increases and the conversion efficiency of the photoelectric conversion element 100A can be improved.

  The other description of the photoelectric conversion element 100A is the same as the description of the photoelectric conversion element 100.

  FIG. 6 is a cross-sectional view showing a configuration of still another photoelectric conversion element according to Embodiment 1. The photoelectric conversion element according to Embodiment 1 may be a photoelectric conversion element 100B illustrated in FIG.

  Referring to FIG. 6, photoelectric conversion element 100B is obtained by adding i-type amorphous films 61 to 6m-1 to photoelectric conversion element 100 shown in FIG. is there.

  The i-type amorphous films 61 to 6m-1 are made of an amorphous phase and are in contact with the n-type single crystal silicon substrate 1 and the n-type amorphous films 21 to 2m-1, respectively. 1 and n-type amorphous films 21-2m-1. Each of the i-type amorphous films 61 to 6m-1 is made of, for example, i-type a-Si and has a film thickness of, for example, 10 nm. The i-type amorphous films 61 to 6m-1 have the same length as the n-type amorphous films 21 to 2m-1 in the direction perpendicular to the paper surface of FIG.

  In the photoelectric conversion element 100B, each of the p-type amorphous films 11 to 1m has a thickness of the n-type amorphous films 21 to 2m-1 and that of the i-type amorphous films 61 to 6m-1. It consists of the total film thickness with the film thickness.

  In the photoelectric conversion element 100B, the end surface of the p-type amorphous film 11 is in contact with the i-type amorphous film 61 and the n-type amorphous film 21, and the end surface of the p-type amorphous film 12 is i. The end surface of the p-type amorphous film 13 is in contact with the i-type amorphous film 61 and the n-type amorphous film 21 and the i-type amorphous film 62 and the n-type amorphous film 22. The end face of the p-type amorphous film 1m-1 is in contact with the film 62 and the n-type amorphous film 22 and the i-type amorphous film 63 and the n-type amorphous film 23. Of the p-type amorphous film 1m in contact with the n-type amorphous film 6m-2 and the n-type amorphous film 2m-2 and the i-type amorphous film 6m-1 and the n-type amorphous film 2m-1. The end face is in contact with the i-type amorphous film 6m-1 and the n-type amorphous film 2m-1.

  The photoelectric conversion element 100B is manufactured by steps (a) to (l) shown in FIGS. In this case, in step (i) of FIG. 3, the i-type amorphous film for the i-type amorphous films 61 to 6m-1 is converted into the n-type single crystal silicon substrate 1 and the p-type amorphous film by the plasma CVD method. Then, the n-type amorphous film 60 is deposited on the i-type amorphous film for the i-type amorphous films 61 to 6m-1 by the plasma CVD method. The gas flow rate when depositing the i-type amorphous film for the i-type amorphous film 61-6m-1 is the same as the gas flow rate of the i-type amorphous film 51-5m shown in Table 1. .

  The power generation mechanism in the photoelectric conversion element 100B is substantially the same as the power generation mechanism in the photoelectric conversion element 100. As described in the photoelectric conversion element 100, electrons and holes are on the light incident side of the n-type single crystal silicon substrate 1. Recombination on the surface (textured surface) is suppressed, and diffusion to the p-type amorphous films 11-1m and n-type amorphous films 21-2m-1 side is facilitated. Then, the electrons and holes diffused toward the p-type amorphous films 11 to 1m and the n-type amorphous films 21 to 2m-1 are transferred to the p-type amorphous films 11 to 1m / n-type single crystal silicon substrate 1. (= Pn junction) is separated by an internal electric field, holes reach the electrodes 31 to 3m via the p-type amorphous films 11 to 1m, and the electrons are i-type amorphous films 61 to 6m-1 And it reaches the electrodes 41-4m-1 through the n-type amorphous films 21-2m-1.

  The electrons that have reached the electrodes 41 to 4m-1 reach the electrodes 31 to 3m via a load connected between the electrodes 31 to 3m and the electrodes 41 to 4m-1, and recombine with the holes.

  As described above, the photoelectric conversion element 100 </ b> B uses electrons and holes photoexcited in the n-type single crystal silicon substrate 1 to convert the back surface of the n-type single crystal silicon substrate 1 (= n-type single crystal silicon on which the oxide film 2 is formed). This is a back contact type photoelectric conversion element taken out from the surface opposite to the surface of the substrate 1.

  The photoelectric conversion element 100B includes an oxide film 2 provided in contact with the light incident side surface (textured surface) of the n-type single crystal silicon substrate 1, and an n-type provided in contact with the oxide film 2. Since the amorphous film 3 is provided, the passivation effect on the n-type single crystal silicon substrate 1 can be improved as described in the photoelectric conversion element 100.

  In the photoelectric conversion element 100B, since the i-type amorphous films 61 to 6m-1 exist between the n-type single crystal silicon substrate 1 and the n-type amorphous films 21 to 2m-1, Recombination of electrons at the interface between the single crystal silicon substrate 1 and the n-type amorphous films 21 to 2m−1 is suppressed. As a result, the short-circuit photocurrent increases and the conversion efficiency of the photoelectric conversion element 100B can be improved.

  The other description of the photoelectric conversion element 100B is the same as the description of the photoelectric conversion element 100.

  FIG. 7 is a cross-sectional view showing a configuration of still another photoelectric conversion element according to the first embodiment. The photoelectric conversion element according to Embodiment 1 may be the photoelectric conversion element 100C illustrated in FIG.

  Referring to FIG. 7, a photoelectric conversion element 100C is obtained by adding i-type amorphous films 51 to 5m and 61 to 6m-1 to the photoelectric conversion element 100 shown in FIG. The same as 100.

  The i-type amorphous films 51 to 5m and 61 to 6m-1 are as described above.

  In the photoelectric conversion element 100C, the end face of the i-type amorphous film 61 is in contact with the i-type amorphous films 51 and 52, and the end face of the i-type amorphous film 62 is the i-type amorphous films 52 and 53. Hereinafter, similarly, the end face of the i-type amorphous film 6m-1 is in contact with the i-type amorphous films 5m-1 and 5m. Further, the end surface of the n-type amorphous film 21 is in contact with the p-type amorphous films 11 and 12, and the end surface of the n-type amorphous film 22 is in contact with the p-type amorphous films 12 and 13. Similarly, the end face of the n-type amorphous film 2m-1 is in contact with the p-type amorphous films 1m-1 and 1m.

  The photoelectric conversion element 100C is manufactured by the steps (a) to (l) shown in FIGS. In this case, in step (d) of FIG. 2, an i-type amorphous film for the i-type amorphous films 51 to 5m is deposited on the n-type single crystal silicon substrate 1 by the plasma CVD method, and then the p-type is formed. A p-type amorphous film 20 for the amorphous films 11 to 1m is deposited on the i-type amorphous film for the i-type amorphous films 51 to 5m by plasma CVD. Further, in step (i) of FIG. 3, the i-type amorphous films for the i-type amorphous films 61 to 6m-1 are converted into n-type single crystal silicon substrate 1 and p-type amorphous film 11 by plasma CVD. After that, the n-type amorphous film 60 for the n-type amorphous films 21 to 2m-1 is deposited on the i-type non-crystalline films 61 to 6m-1 by the plasma CVD method. Deposited on the crystalline film. The gas flow rates when depositing the i-type amorphous film for the i-type amorphous films 51 to 5m and the i-type amorphous film for the i-type amorphous films 61 to 6m-1 are the same. Yes, as shown in Table 1.

  The power generation mechanism in the photoelectric conversion element 100C is substantially the same as the power generation mechanism in the photoelectric conversion element 100. As described in the photoelectric conversion element 100, electrons and holes are on the light incident side of the n-type single crystal silicon substrate 1. Recombination on the surface (textured surface) is suppressed, and diffusion to the p-type amorphous films 11-1m and n-type amorphous films 21-2m-1 side is facilitated. Then, the electrons and holes diffused toward the p-type amorphous film 11 to 1 m and the n-type amorphous film 21 to 2 m−1 side are converted into the p-type amorphous film 11 to 1 m / i-type amorphous film 51. ~ 5 m / n type single crystal silicon substrate 1 (= pin junction) is separated by an internal electric field, and holes are separated by electrodes 31 via i-type amorphous films 51 to 5 m and p-type amorphous films 11 to 1 m. To 3 m, and the electrons reach the electrodes 41 to 4 m−1 via the i-type amorphous films 61 to 6 m−1 and the n-type amorphous films 21 to 2 m−1.

  The electrons that have reached the electrodes 41 to 4m-1 reach the electrodes 31 to 3m via a load connected between the electrodes 31 to 3m and the electrodes 41 to 4m-1, and recombine with the holes.

  As described above, the photoelectric conversion element 100 </ b> C allows electrons and holes photoexcited in the n-type single crystal silicon substrate 1 to be transferred to the back surface of the n-type single crystal silicon substrate 1 (= n-type single crystal silicon on which the oxide film 2 is formed). This is a back contact type photoelectric conversion element taken out from the surface opposite to the surface of the substrate 1.

  The photoelectric conversion element 100C includes an oxide film 2 provided in contact with the light incident side surface (textured surface) of the n-type single crystal silicon substrate 1, and an n-type provided in contact with the oxide film 2. Since the amorphous film 3 is provided, the passivation effect on the n-type single crystal silicon substrate 1 can be improved as described in the photoelectric conversion element 100.

  In the photoelectric conversion element 100C, since the i-type amorphous films 51 to 5m exist between the n-type single crystal silicon substrate 1 and the p-type amorphous films 11 to 1m, the n-type single crystal silicon substrate Recombination of holes at the interface between 1 and the p-type amorphous films 11 to 1 m is suppressed. Furthermore, in the photoelectric conversion element 100C, since the i-type amorphous films 61 to 6m-1 exist between the n-type single crystal silicon substrate 1 and the n-type amorphous films 21 to 2m-1, Recombination of electrons at the interface between the single crystal silicon substrate 1 and the n-type amorphous films 21 to 2m−1 is suppressed.

  As a result, the short-circuit photocurrent increases and the conversion efficiency of the photoelectric conversion element 100C can be improved.

  The other description of the photoelectric conversion element 100C is the same as the description of the photoelectric conversion element 100.

  In the photoelectric conversion elements 100, 100A, 100B, and 100C, the light incident side surface (= the surface on which the oxide film 2 is formed) of the n-type single crystal silicon substrate 1 may not have a texture structure. In this case, step (b) in FIG. 2 is omitted.

  In the photoelectric conversion elements 100, 100A, 100B, and 100C, the p-type amorphous films 11 to 1m are described as being made of p-type a-Si. However, in the first embodiment, the present invention is not limited to this. The type amorphous films 11 to 1m are made of any of p-type a-SiC, p-type a-SiO, p-type a-SiN, p-type a-SiCN, p-type a-SiGe, and p-type a-Ge. It may be.

  Furthermore, in the photoelectric conversion elements 100, 100A, 100B, and 100C, it has been described that the n-type amorphous films 3 and 21 to 2m-1 are made of n-type a-Si. The n-type amorphous films 21 to 2m-1 are not limited to n-type a-SiC, n-type a-SiO, n-type a-SiN, n-type a-SiCN, n-type a-SiGe, and n-type a-. It may consist of either Ge.

  Further, in the photoelectric conversion elements 100A and 100C, the i-type amorphous films 51 to 5m have been described as being made of i-type a-Si. However, in the first embodiment, the i-type amorphous film is not limited thereto. The films 51 to 5m may be made of any of i-type a-SiC, i-type a-SiO, i-type a-SiN, i-type a-SiCN, and i-type a-SiGe.

  Further, in the photoelectric conversion elements 100B and 100C, it has been described that the i-type amorphous films 61 to 6m-1 are made of i-type a-Si. However, in the first embodiment, the i-type non-film is not limited to this. The crystalline films 61 to 6m-1 may be made of any of i-type a-SiC, i-type a-SiO, i-type a-SiN, i-type a-SiCN, and i-type a-SiGe.

  That is, in the photoelectric conversion elements 100, 100A, 100B, and 100C, the p-type amorphous films 11 to 1m and the n-type amorphous films 3 and 21 to 2m-1 are each one of the materials shown in Table 2. In the photoelectric conversion elements 100A, 100B, and 100C, the i-type amorphous films 51 to 5m and / or the i-type amorphous films 61 to 6m-1 are materials shown in Table 2, respectively. It may consist of either.

In this case, the p-type a-SiC is formed by the above-described plasma CVD method using SiH ₄ gas, methane (CH ₄ ) gas, B ₂ H ₆ gas, and H ₂ gas as material gases. The p-type a-SiO is formed by the above-described plasma CVD method using SiH ₄ gas, oxygen (O ₂ ) gas, B ₂ H ₆ gas and H ₂ gas as material gases. The p-type a-SiN is formed by the above-described plasma CVD method using SiH ₄ gas, ammonia (NH ₃ ) gas, B ₂ H ₆ gas and H ₂ gas as material gases. The p-type a-SiCN is formed by the above-described plasma CVD method using SiH ₄ gas, CH ₄ gas, NH ₃ gas, B ₂ H ₆ gas and H ₂ gas as material gases. The p-type a-SiGe is formed by the above-described plasma CVD method using SiH ₄ gas, germane (GeH ₄ ) gas, B ₂ H ₆ gas and H ₂ gas as material gases. The p-type a-Ge is formed by the above-described plasma CVD method using GeH ₄ gas, B ₂ H ₆ gas, and H ₂ gas as material gases.

The n-type a-SiC is formed by the above-described plasma CVD method using SiH ₄ gas, CH ₄ gas, PH ₃ gas, and H ₂ gas as material gases. The n-type a-SiO is formed by the above-described plasma CVD method using SiH ₄ gas, O ₂ gas, PH ₃ gas, and H ₂ gas as material gases. The n-type a-SiN is formed by the above-described plasma CVD method using SiH ₄ gas, NH ₃ gas, PH ₃ gas, and H ₂ gas as material gases. The n-type a-SiCN is formed by the above-described plasma CVD method using SiH ₄ gas, CH ₄ gas, NH ₃ gas, PH ₃ gas, and H ₂ gas as material gases. The n-type a-SiGe is formed by the above-described plasma CVD method using SiH ₄ gas, GeH ₄ gas, PH ₃ gas, and H ₂ gas as material gases. The n-type a-Ge is formed by the above-described plasma CVD method using GeH ₄ gas, PH ₃ gas, and H ₂ gas as material gases.

Furthermore, i-type a-SiC is formed by the above-described plasma CVD method using SiH ₄ gas, CH ₄ gas, and H ₂ gas as material gases. i-type a-SiO is formed by the above-described plasma CVD method using SiH ₄ gas, O ₂ gas, and H ₂ gas as material gases. i-type a-SiN is formed by the above-described plasma CVD method using SiH ₄ gas, NH ₃ gas, and H ₂ gas as material gases. The i-type a-SiCN is formed by the above-described plasma CVD method using SiH ₄ gas, CH ₄ gas, NH ₃ gas, and H ₂ gas as material gases. i-type a-SiGe is formed by the above-described plasma CVD method using SiH ₄ gas, GeH ₄ gas, and H ₂ gas as material gases.

  Note that i-type a-Ge is also assumed as the i-type amorphous films 51 to 5m and 61 to 6m-1, but the i-type a-Ge has an optical band gap larger than that of the n-type single crystal silicon substrate 1. Therefore, when i-type a-Ge is used as the i-type amorphous films 51 to 5m and 61 to 6m-1, it is difficult to improve the open circuit voltage Voc. This is because in the photoelectric conversion elements 100, 100A, 100B, and 100C, the optical band gaps of the i-type amorphous films 51 to 5m and 61 to 6m-1 determine the open circuit voltage Voc dominantly.

  Therefore, in the first embodiment, i-type a-SiC, i-type a-SiO, i-type a-SiN, i-type a-SiCN, and i-type a that are larger than the optical band gap of the n-type single crystal silicon substrate 1. -Si, i-type a-SiGe was used as the i-type amorphous films 51-5m and 61-6m-1.

  As described above, the photoelectric conversion element according to the first embodiment is a back-contact type photoelectric conversion element in which a heterojunction is formed on the back surface of the n-type single crystal silicon substrate 1, and the light incident on the n-type single crystal silicon substrate 1. It has a structure in which an oxide film 2 and an n-type amorphous film 3 are sequentially laminated on the surface on the side. Therefore, the recombination of carriers (particularly, holes) on the light incident side surface of the n-type single crystal silicon substrate 1 is caused by the reduction of the interface state due to the oxide film 2 and the FSF effect due to the n-type amorphous film 3. This can suppress the passivation effect on the n-type single crystal silicon substrate 1.

[Embodiment 2]
FIG. 8 is a cross-sectional view showing the configuration of the photoelectric conversion element according to the second embodiment. Referring to FIG. 8, the photoelectric conversion element 200 according to the second embodiment includes a p-type single crystal silicon substrate 101, an oxide film 102, p-type amorphous films 103, 121 to 12m-1, and an antireflection film. 104, n-type amorphous films 111 to 11m, and electrodes 131 to 13m and 141 to 14m-1.

  The p-type single crystal silicon substrate 101 has, for example, a (100) plane orientation and a specific resistance of 0.1 to 1.0 Ω · cm. The p-type single crystal silicon substrate 101 has a thickness of 100 to 300 μm, for example, and preferably has a thickness of 100 to 200 μm. Furthermore, the p-type single crystal silicon substrate 101 has a textured surface on the light incident side.

The oxide film 102 is made of, for example, SiO ₂ and is provided in contact with the light incident side surface of the p-type single crystal silicon substrate 101. The oxide film 102 has a film thickness of several nm, for example.

The p-type amorphous film 103 is made of an amorphous phase, for example, p-type a-Si. The p-type amorphous film 103 has a thickness of 10 nm to several tens of nm, for example. Furthermore, the B concentration of the p-type amorphous layer 103 is 1 × 10 ¹⁸ cm ⁻³ to 1 × 10 ²⁰ cm ⁻³ . The p-type amorphous film 103 is formed in contact with the oxide film 102.

The antireflection film 104 is made of, for example, Si ₃ N ₄ and has a film thickness of, for example, 100 nm. The antireflection film 104 is provided in contact with the p-type amorphous film 103.

Each of n-type amorphous films 111 to 11m is made of an amorphous phase, and is provided in contact with the surface of p-type single crystal silicon substrate 101 opposite to the light incident side. Each of the n-type amorphous films 111 to 11m is made of, for example, n-type a-Si and has a film thickness of, for example, 10 nm. The n-type amorphous films 111 to 11m are arranged at a desired interval in the in-plane direction of the p-type single crystal silicon substrate 101. Furthermore, the P concentration in each of the n-type amorphous films 111 to 11m is, for example, 5 × 10 ¹⁹ cm ⁻³ .

  Each of the p-type amorphous films 121 to 12m-1 is made of an amorphous phase. The p-type amorphous film 121 is disposed in contact with the n-type amorphous films 111 and 112 and the p-type single crystal silicon substrate 101, and the p-type amorphous film 122 is composed of the n-type amorphous films 112 and 113. In the same manner, the p-type amorphous film 12m-1 is divided into the n-type amorphous films 11m-1 and 11m and the p-type single crystal silicon substrate 101. It is arranged in contact with.

Each of the p-type amorphous films 121 to 12m−1 is made of, for example, p-type a-Si, and has a film thickness of, for example, 10 nm. Further, the B concentration in each of the p-type amorphous films 121 to 12m−1 is, for example, 5 × 10 ¹⁹ cm ⁻³ .

  The electrodes 131 to 13m are provided in contact with the n-type amorphous films 111 to 11m, respectively. The electrodes 141 to 14m-1 are provided in contact with the p-type amorphous films 121 to 12m-1, respectively. And each of the electrodes 131-13m and 141-14m-1 consists of Ag, for example.

  The n-type amorphous films 111 to 11m and the p-type amorphous films 121 to 12m-1 have the same length in the direction perpendicular to the paper surface of FIG. The area occupation ratio, which is the ratio of the entire area of the n-type amorphous films 111 to 11m to the area of the p-type single crystal silicon substrate 101, is 60 to 93%. The area occupation ratio, which is the ratio of the entire area of 12m−1 to the area of the p-type single crystal silicon substrate 101, is 5 to 20%.

  As described above, the area occupation ratio of the n-type amorphous films 111 to 11m is made larger than the area occupation ratio of the p-type amorphous films 121 to 12m-1 in the p-type single crystal silicon substrate 101. The separated electrons and holes are easily separated by the pn junction (n-type amorphous film 111-11m / p-type single crystal silicon substrate 101), and the contribution rate of photoexcited electrons and holes to power generation is increased. Because.

  The photoelectric conversion element 200 is manufactured according to the steps (a) to (l) shown in FIGS. In this case, n-type single crystal silicon substrate 1, oxide film 2, n-type amorphous film 3, antireflection film 4, p-type amorphous films 11-1m, n-type amorphous films 21-2m-1, and The electrodes 31 to 3m and 41 to 4m−1 are respectively connected to the p-type single crystal silicon substrate 101, the oxide film 102, the p-type amorphous film 103, the antireflection film 104, the n-type amorphous films 111 to 11m, and the p-type non-electrode. What is necessary is just to read as crystalline film 121-12m-1, electrode 131-13m, 141-14m-1. The oxide film 102 is formed by the same method as the oxide film 2, and the p-type amorphous films 103 and 121-12m-1 are made of the same material gas and p-type amorphous films 11-1m shown in Table 1. It is formed by the plasma CVD method using the same conditions as those for the p-type amorphous films 11 to 1m. The n-type amorphous films 111 to 11m are formed using the same material gas as the n-type amorphous films 21 to 2m-1 shown in Table 1 and the same conditions as the conditions of the n-type amorphous films 21 to 2m-1. It is formed by a plasma CVD method. The antireflection film 104 is formed by the same method as the antireflection film 4.

  In the photoelectric conversion element 200, when sunlight is irradiated onto the photoelectric conversion element 200 from the antireflection film 104 side, electrons and holes are photoexcited in the p-type single crystal silicon substrate 101.

  Even if the photoexcited electrons and holes diffuse to the oxide film 102 side, the passivation effect of the p-type single crystal silicon substrate 101 by the oxide film 102 and the FSF effect (surface electric field effect) by the p-type amorphous film 103 It becomes difficult to recombine, and it becomes easy to diffuse to the n-type amorphous films 111 to 11m and the p-type amorphous films 121 to 12m-1.

More specifically, since the oxide film 102 (= SiO ₂ ) is in contact with the textured surface of the p-type single crystal silicon substrate 101, the p-type single crystal silicon substrate 101 and the oxide film 102 (= SiO ₂ ) The interface state density at the interface is very low, 10 ¹⁰ cm ⁻² to 10 ¹¹ cm ⁻² . As a result, carriers (electrons and holes) hardly recombine on the textured surface of the p-type single crystal silicon substrate 101. Since the thickness of the oxide film 102 is several nm as described above, carriers (electrons and holes) are separated from the p-type single crystal silicon substrate 101 and the oxide film by the FSF effect of the p-type amorphous film 103. It becomes difficult to reach the interface with 102, and recombination is further suppressed. In particular, recombination of electrons that are minority carriers is suppressed. That is, the optical band gap (= about 1.7 eV) and activation energy (= about 0.3 eV to 0.4 eV) of p-type a-Si constituting the p-type amorphous film 103 and the p-type single crystal silicon substrate When the optical band gap (= 1.1 eV) and activation energy (= 0.2 eV to 0.3 eV) of 101 are taken into consideration, the end of the p-type a-Si conduction band corresponds to the p-type single crystal silicon substrate 101. The p-type amorphous film 103 generates a surface electric field in the vicinity of the surface of the p-type single crystal silicon substrate 101 because it exists on the high energy side by 0.4 eV to 0.6 eV from the end of the conduction band. As a result, electrons diffused near the surface of the p-type single crystal silicon substrate 101 are unlikely to reach the interface between the p-type single crystal silicon substrate 101 and the oxide film 102 due to the surface electric field generated by the p-type amorphous film 103. Therefore, recombination of electrons that are minority carriers is suppressed by the FSF effect.

  Thus, carriers (electrons and holes) are suppressed from recombination on the surface of the p-type single crystal silicon substrate 101 by the oxide film 102 and the p-type amorphous film 103, and the n-type amorphous films 111 to 11m. And it becomes easy to diffuse to the p-type amorphous films 121 to 12m−1 side.

  Then, the electrons and holes diffused toward the n-type amorphous films 111 to 11m and the p-type amorphous films 121 to 12m-1 are transferred to the n-type amorphous films 111 to 11m / p-type single crystal silicon substrate 101. The electrons are separated by the internal electric field due to (= pn junction), the electrons reach the electrodes 131 to 13m through the n-type amorphous films 111 to 11m, and the holes are the p-type amorphous films 121 to 12m-1. To reach the electrodes 141-14m-1.

  The electrons that have reached the electrodes 131 to 13m reach the electrodes 141 to 14m-1 via a load connected between the electrodes 131 to 13m and the electrodes 141 to 14m-1, and recombine with the holes.

  In this way, the photoelectric conversion element 200 converts electrons and holes photoexcited in the p-type single crystal silicon substrate 101 into the back surface of the p-type single crystal silicon substrate 101 (= p-type single crystal silicon on which the oxide film 102 is formed). This is a back-contact photoelectric conversion element that is taken out from the surface opposite to the surface of the substrate 101.

  Since the photoelectric conversion element 200 includes the oxide film 102 and the p-type amorphous film 103 on the light incident side, the passivation effect on the p-type single crystal silicon substrate 101 can be improved as described above.

  Further, as described in the photoelectric conversion element 100, the surface on the light receiving surface side of the p-type single crystal silicon substrate 101 can be protected in the manufacturing process of the photoelectric conversion element 200.

  FIG. 9 is a cross-sectional view showing a configuration of another photoelectric conversion element according to the second embodiment. The photoelectric conversion element according to Embodiment 2 may be a photoelectric conversion element 200A shown in FIG.

  Referring to FIG. 9, a photoelectric conversion element 200 </ b> A is obtained by adding i-type amorphous films 151 to 15 m to the photoelectric conversion element 200 illustrated in FIG. 8, and is otherwise the same as the photoelectric conversion element 200.

  The i-type amorphous films 151 to 15m are made of an amorphous phase and are in contact with the p-type single crystal silicon substrate 101 and the n-type amorphous films 111 to 11m, respectively. It arrange | positions between the amorphous | non-crystalline films 111-11m. Each of the i-type amorphous films 151 to 15m is made of, for example, i-type a-Si, and has a film thickness of, for example, 10 nm. Further, the i-type amorphous films 151 to 15m have the same width as the n-type amorphous films 111 to 11m in the in-plane direction of the p-type single crystal silicon substrate 101 (the left-right direction in the paper surface of FIG. 9), respectively. Have. Furthermore, the i-type amorphous films 151 to 15m have the same length as the n-type amorphous films 111 to 11m, respectively, in the direction perpendicular to the paper surface of FIG.

  In the photoelectric conversion element 200A, the thicknesses of the p-type amorphous films 121 to 12m−1 are the thicknesses of the n-type amorphous films 111 to 11m and the i-type amorphous films 151 to 15m, respectively. And the total film thickness.

  In the photoelectric conversion element 200A, the end surface of the i-type amorphous film 151 is in contact with the p-type amorphous film 121, and the end surface of the i-type amorphous film 152 is the p-type amorphous film 121, 122. The end surface of the i-type amorphous film 153 is in contact with the p-type amorphous films 122 and 123. Similarly, the end surface of the i-type amorphous film 15m-1 is the p-type amorphous film. The end faces of the i-type amorphous film 15m are in contact with the p-type amorphous film 12m-1 in contact with the films 12m-2 and 12m-1.

  200 A of photoelectric conversion elements are manufactured by the process (a)-process (l) shown in FIGS. In this case, in the step (d) of FIG. 2, an i-type amorphous film for the i-type amorphous films 151 to 15m is deposited on the p-type single crystal silicon substrate 101 by the plasma CVD method. An n-type amorphous film for the amorphous films 111 to 11m is deposited on the i-type amorphous film for the i-type amorphous films 151 to 15m by a plasma CVD method. The gas flow rate when depositing the i-type amorphous film for the i-type amorphous films 151 to 15m is the same as the gas flow rate of the i-type amorphous films 51 to 5m shown in Table 1, and n The gas flow rate when depositing the n-type amorphous film for the n-type amorphous films 111 to 11m is the same as the gas flow rate of the n-type amorphous films 21 to 2m-1 shown in Table 1.

  The power generation mechanism in the photoelectric conversion element 200 </ b> A is substantially the same as the power generation mechanism of the photoelectric conversion element 200, and as described in the photoelectric conversion element 200, electrons and holes are on the light incident side of the p-type single crystal silicon substrate 101. Recombination on the surface (textured surface) is suppressed, and diffusion to the n-type amorphous films 111 to 11m and p-type amorphous films 121 to 12m-1 side is facilitated. The electrons and holes diffused toward the n-type amorphous films 111 to 11m and the p-type amorphous films 121 to 12m-1 are converted into the n-type amorphous films 111 to 11m / i-type amorphous film 151. ~ 15m / p type single crystal silicon substrate 101 (= pin junction) is separated by an internal electric field, and electrons are separated from the electrodes 131 through the i-type amorphous films 151 to 15m and the n-type amorphous films 111 to 11m. The holes reach 13m, and the holes reach the electrodes 141-14m-1 through the p-type amorphous films 121-12m-1.

  The electrons that have reached the electrodes 131 to 13m reach the electrodes 141 to 14m-1 via a load connected between the electrodes 131 to 13m and the electrodes 141 to 14m-1, and recombine with the holes.

  As described above, the photoelectric conversion element 200A allows electrons and holes photoexcited in the p-type single crystal silicon substrate 101 to be transferred to the back surface of the p-type single crystal silicon substrate 101 (= p-type single crystal silicon on which the oxide film 102 is formed). This is a back-contact photoelectric conversion element that is taken out from the surface opposite to the surface of the substrate 101.

  The photoelectric conversion element 200A includes an oxide film 102 provided in contact with the light incident surface (textured surface) of the p-type single crystal silicon substrate 101, and a p-type provided in contact with the oxide film 102. Since the amorphous film 103 is provided, the passivation effect on the p-type single crystal silicon substrate 101 can be improved as described in the photoelectric conversion element 200.

  In the photoelectric conversion element 200A, since the i-type amorphous films 151 to 15m exist between the p-type single crystal silicon substrate 101 and the n-type amorphous films 111 to 11m, the p-type single crystal silicon substrate Recombination of electrons at the interface between 101 and the n-type amorphous films 111 to 11m is suppressed. As a result, the short-circuit photocurrent increases and the conversion efficiency of the photoelectric conversion element 200A can be improved.

  The other description of the photoelectric conversion element 200A is the same as the description of the photoelectric conversion element 200.

  FIG. 10 is a cross-sectional view illustrating a configuration of still another photoelectric conversion element according to the second embodiment. The photoelectric conversion element according to Embodiment 2 may be a photoelectric conversion element 200B shown in FIG.

  Referring to FIG. 10, photoelectric conversion element 200B is obtained by adding i-type amorphous films 161 to 16m-1 to photoelectric conversion element 200 shown in FIG. is there.

  The i-type amorphous films 161 to 16m-1 are made of an amorphous phase and are in contact with the p-type single crystal silicon substrate 101 and the p-type amorphous films 121 to 12m-1, respectively. 101 and the p-type amorphous films 121 to 12m-1. Each of the i-type amorphous films 161 to 16m-1 is made of, for example, i-type a-Si and has a film thickness of, for example, 10 nm. The i-type amorphous films 161 to 16m-1 have the same length as the p-type amorphous films 121 to 12m-1 in the direction perpendicular to the paper surface of FIG.

  In the photoelectric conversion element 200B, each of the n-type amorphous films 111 to 11m has a thickness of the p-type amorphous films 121 to 12m-1 and that of the i-type amorphous films 161 to 16m-1. It consists of the total film thickness with the film thickness.

  In the photoelectric conversion element 200B, the end surface of the n-type amorphous film 111 is in contact with the i-type amorphous film 161 and the p-type amorphous film 121, and the end surface of the n-type amorphous film 112 is i. The end face of the n-type amorphous film 113 is in contact with the i-type amorphous film 161 and the p-type amorphous film 121 and the i-type amorphous film 162 and the p-type amorphous film 122. The end face of the n-type amorphous film 11m-1 is in contact with the film 162 and the p-type amorphous film 122, the i-type amorphous film 163 and the p-type amorphous film 123. The n-type amorphous film 11m is in contact with the n-type amorphous film 16m-2 and the p-type amorphous film 12m-2 and the i-type amorphous film 16m-1 and the p-type amorphous film 12m-1. The end face is in contact with the i-type amorphous film 16m-1 and the p-type amorphous film 12m-1.

  The photoelectric conversion element 200B is manufactured by steps (a) to (l) illustrated in FIGS. In this case, in step (i) of FIG. 3, the i-type amorphous films for the i-type amorphous films 161 to 16m-1 are converted into the p-type single crystal silicon substrate 101 and the n-type amorphous film by the plasma CVD method. Then, the p-type amorphous film for the p-type amorphous films 121 to 12m-1 is deposited on the i-type amorphous films 161 to 16m-1 by the plasma CVD method. Deposited on the crystalline film. The gas flow rate when depositing the i-type amorphous film for the i-type amorphous film 161 to 16m-1 is the same as the gas flow rate of the i-type amorphous film 51 to 5m shown in Table 1. The gas flow rate when depositing the p-type amorphous film for the p-type amorphous films 121 to 12m-1 is the same as the gas flow rate of the p-type amorphous films 11 to 1m shown in Table 1.

  The power generation mechanism in the photoelectric conversion element 200B is substantially the same as the power generation mechanism in the photoelectric conversion element 200. As described in the photoelectric conversion element 200, electrons and holes are generated on the light incident side of the p-type single crystal silicon substrate 101. Recombination on the surface (textured surface) is suppressed, and diffusion to the n-type amorphous films 111 to 11m and p-type amorphous films 121 to 12m-1 side is facilitated. Then, the electrons and holes diffused toward the n-type amorphous films 111 to 11m and the p-type amorphous films 121 to 12m-1 are transferred to the n-type amorphous films 111 to 11m / p-type single crystal silicon substrate 101. (= Pn junction) is separated by an internal electric field, electrons reach the electrodes 131 to 13m via the n-type amorphous films 111 to 11m, and the holes are i-type amorphous films 161 to 16m-1. And it reaches the electrodes 141-14m-1 through the p-type amorphous films 121-12m-1.

  The electrons that have reached the electrodes 131 to 13m-1 reach the electrodes 141 to 14m-1 via a load connected between the electrodes 131 to 13m-1 and the electrodes 141 to 14m-1, and are regenerated with holes. Join.

  As described above, the photoelectric conversion element 200B converts the electrons and holes photoexcited in the p-type single crystal silicon substrate 101 into the back surface of the p-type single crystal silicon substrate 101 (= p-type single crystal silicon on which the oxide film 102 is formed). This is a back-contact photoelectric conversion element that is taken out from the surface opposite to the surface of the substrate 101.

  The photoelectric conversion element 200B includes an oxide film 102 provided in contact with the light incident surface (textured surface) of the p-type single crystal silicon substrate 101, and a p-type provided in contact with the oxide film 102. Since the amorphous film 103 is provided, the passivation effect on the p-type single crystal silicon substrate 101 can be improved as described in the photoelectric conversion element 200.

  In the photoelectric conversion element 200B, since the i-type amorphous films 161 to 16m-1 exist between the p-type single crystal silicon substrate 101 and the p-type amorphous films 121 to 12m-1, the p-type Recombination of holes at the interface between the single crystal silicon substrate 101 and the p-type amorphous films 121 to 12m−1 is suppressed. As a result, the short-circuit photocurrent increases and the conversion efficiency of the photoelectric conversion element 200B can be improved.

  The other description of the photoelectric conversion element 200B is the same as the description of the photoelectric conversion element 200.

  FIG. 11 is a cross-sectional view illustrating a configuration of still another photoelectric conversion element according to the second embodiment. The photoelectric conversion element according to Embodiment 2 may be a photoelectric conversion element 200C shown in FIG.

  Referring to FIG. 11, a photoelectric conversion element 200C is obtained by adding i-type amorphous films 151 to 15m and 161 to 16m-1 to the photoelectric conversion element 200 shown in FIG. The same as 200.

  The i-type amorphous films 151 to 15m and 161 to 16m-1 are as described above.

  In the photoelectric conversion element 200C, the end face of the i-type amorphous film 161 is in contact with the i-type amorphous films 151 and 152, and the end face of the i-type amorphous film 162 is the i-type amorphous films 152 and 153. Hereinafter, similarly, the end face of the i-type amorphous film 16m-1 is in contact with the i-type amorphous films 15m-1 and 15m. The end face of the p-type amorphous film 121 is in contact with the n-type amorphous films 111 and 112, and the end face of the p-type amorphous film 122 is in contact with the n-type amorphous films 112 and 113. Similarly, the end face of the p-type amorphous film 12m-1 is in contact with the n-type amorphous films 11m-1 and 11m.

  The photoelectric conversion element 200C is manufactured by the steps (a) to (l) shown in FIGS. In this case, in the step (d) of FIG. 2, an i-type amorphous film for the i-type amorphous films 151 to 15m is deposited on the p-type single crystal silicon substrate 101 by the plasma CVD method. An n-type amorphous film for the amorphous films 111 to 11m is deposited on the i-type amorphous film for the i-type amorphous films 151 to 15m by a plasma CVD method. Further, in step (i) of FIG. 3, the i-type amorphous films for the i-type amorphous films 161 to 16m-1 are converted into the p-type single crystal silicon substrate 101 and the n-type amorphous film 111 by the plasma CVD method. After that, a p-type amorphous film for the p-type amorphous films 121 to 12m-1 is formed into an i-type amorphous film for the i-type amorphous films 161 to 16m-1 by a plasma CVD method. Deposited on the material film. The gas flow rate when depositing the i-type amorphous film for the i-type amorphous films 151 to 15m and the i-type amorphous film for the i-type amorphous films 161 to 16m-1 is: The gas flow rate when depositing n-type amorphous films for n-type amorphous films 111 to 11m is the same as the gas flow rate when depositing i-type amorphous films 51 to 5m shown in Table 1. The gas flow rate when depositing the n-type amorphous films 21 to 2m-1 shown in Table 1 is the same as that for depositing the p-type amorphous films for the p-type amorphous films 121 to 12m-1. The gas flow rate at that time is the same as the gas flow rate when the p-type amorphous films 11 to 1m shown in Table 1 are deposited.

  The power generation mechanism in the photoelectric conversion element 200C is substantially the same as the power generation mechanism in the photoelectric conversion element 200. As described in the photoelectric conversion element 200, electrons and holes are generated on the light incident side of the p-type single crystal silicon substrate 101. Recombination on the surface (textured surface) is suppressed, and diffusion to the n-type amorphous films 111 to 11m and p-type amorphous films 121 to 12m-1 side is facilitated. The electrons and holes diffused toward the n-type amorphous films 111 to 11m and the p-type amorphous films 121 to 12m-1 are converted into the n-type amorphous films 111 to 11m / i-type amorphous film 151. ~ 15m / p type single crystal silicon substrate 101 (= pin junction) is separated by an internal electric field, and electrons are separated from the electrodes 131 through the i-type amorphous films 151 to 15m and the n-type amorphous films 111 to 11m. The holes reach 13m, and the holes reach the electrodes 141 to 14m-1 via the i-type amorphous films 161 to 16m-1 and the p-type amorphous films 121 to 12m-1.

  The electrons that have reached the electrodes 131 to 13m reach the electrodes 141 to 14m-1 via a load connected between the electrodes 131 to 13m and the electrodes 141 to 14m-1, and recombine with the holes.

  As described above, the photoelectric conversion element 200C uses electrons and holes photoexcited in the p-type single crystal silicon substrate 101 to convert the back surface of the p-type single crystal silicon substrate 101 (= p-type single crystal silicon on which the oxide film 102 is formed). This is a back-contact photoelectric conversion element that is taken out from the surface opposite to the surface of the substrate 101.

  The photoelectric conversion element 200C includes an oxide film 102 provided in contact with the light incident surface (textured surface) of the p-type single crystal silicon substrate 101, and a p-type provided in contact with the oxide film 102. Since the amorphous film 103 is provided, the passivation effect on the p-type single crystal silicon substrate 101 can be improved as described in the photoelectric conversion element 200.

  In the photoelectric conversion element 200C, since the i-type amorphous films 151 to 15m exist between the p-type single crystal silicon substrate 101 and the n-type amorphous films 111 to 11m, the p-type single crystal silicon substrate Recombination of electrons at the interface between 101 and the n-type amorphous films 111 to 11m is suppressed. Further, in the photoelectric conversion element 200C, since the i-type amorphous films 161 to 16m-1 exist between the p-type single crystal silicon substrate 101 and the p-type amorphous films 121 to 12m-1, the p-type Recombination of holes at the interface between the single crystal silicon substrate 101 and the p-type amorphous films 121 to 12m−1 is suppressed.

  As a result, the short-circuit photocurrent increases and the conversion efficiency of the photoelectric conversion element 200C can be improved.

  The other description of the photoelectric conversion element 200C is the same as the description of the photoelectric conversion element 200.

  In the photoelectric conversion elements 200, 200A, 200B, and 200C, the light incident side surface (= the surface on which the oxide film 102 is formed) of the p-type single crystal silicon substrate 101 may not have a texture structure. In this case, step (b) in FIG. 2 is omitted.

  In the photoelectric conversion elements 200, 200A, 200B, and 200C, the n-type amorphous films 111 to 11m-1 are described as being made of n-type a-Si. However, in the second embodiment, the present invention is not limited thereto. The n-type amorphous films 111 to 11m-1 are made of n-type a-SiC, n-type a-SiO, n-type a-SiN, n-type a-SiCN, n-type a-SiGe, and n-type a-Ge. It may consist of either.

  Further, in the photoelectric conversion elements 200, 200A, 200B, and 200C, it has been described that the p-type amorphous films 103 and 121 to 12m are made of p-type a-Si. However, in the second embodiment, the present invention is not limited thereto. The p-type amorphous films 103 and 121 to 12m are made of p-type a-SiC, p-type a-SiO, p-type a-SiN, p-type a-SiCN, p-type a-SiGe, and p-type a-Ge. It may consist of either.

  Further, in the photoelectric conversion elements 200A and 200C, the i-type amorphous films 151 to 15m have been described as being made of i-type a-Si. However, in the second embodiment, the i-type amorphous film is not limited thereto. The films 151 to 15m may be made of any of i-type a-SiC, i-type a-SiO, i-type a-SiN, i-type a-SiCN, and i-type a-SiGe.

  Further, in the photoelectric conversion elements 200B and 200C, the i-type amorphous films 161 to 16m-1 have been described as being made of i-type a-Si. However, in the second embodiment, the i-type non-film is not limited to this. The crystalline films 161 to 16m-1 may be made of any of i-type a-SiC, i-type a-SiO, i-type a-SiN, i-type a-SiCN, and i-type a-SiGe.

  That is, in the photoelectric conversion elements 200, 200A, 200B, and 200C, the n-type amorphous films 111 to 11m and the p-type amorphous films 103 and 121 to 12m-1 are respectively n-type amorphous films shown in Table 2. It may be made of any of the materials constituting the material films 21-2m-1 and the p-type amorphous films 11-1m. In the photoelectric conversion elements 200A, 200B, 200C, the i-type amorphous films 151- 15m and / or i-type amorphous films 161 to 16m-1 may be made of any of the materials constituting i-type amorphous films 51 to 5m and 61 to 6m-1 shown in Table 2, respectively. Good.

  N-type a-SiC, n-type a-SiO, n-type a-SiN, n-type a-SiCN, n-type a-SiGe, n-type a-Ge, p-type a-SiC, p-type a-SiO, p-type a-SiN, p-type a-SiCN, p-type a-SiGe, p-type a-Ge, i-type a-SiC, i-type a-SiO, i-type a-SiN, i-type a-SiCN, and i The type a-SiGe is formed by the plasma CVD method using the material gas described above.

  Note that i-type a-Ge is excluded as a material for the i-type amorphous films 151 to 15m and 161 to 16m-1 because the i-type amorphous films 51 to 5m and 61 to 6m-1 described above are excluded. This is the same as the reason why i-type a-Ge is excluded as a material.

  As described above, the photoelectric conversion element according to Embodiment 2 is a back-contact type photoelectric conversion element in which a heterojunction is formed on the back surface of the p-type single crystal silicon substrate 101, and the light incident side of the p-type single crystal silicon substrate 101. In this structure, an oxide film 102 and a p-type amorphous film 103 are sequentially stacked on the surface. Therefore, the recombination of carriers (particularly electrons) on the light incident side surface of the p-type single crystal silicon substrate 101 is suppressed by the reduction of the interface state due to the oxide film 102 and the FSF effect due to the p-type amorphous film 103. In addition, the passivation effect on the p-type single crystal silicon substrate 101 can be improved.

  As described above, in the first embodiment, the photoelectric conversion elements 100, 100A, 100B, and 100C including the oxide film 2 and the n-type amorphous film 3 on the light incident side surface of the n-type single crystal silicon substrate 1 are used. Explained. In the second embodiment, the photoelectric conversion elements 200, 200A, 200B, and 200C including the oxide film 102 and the n-type amorphous film 103 on the light incident side surface of the p-type single crystal silicon substrate 101 have been described. .

  Therefore, the photoelectric conversion element according to the embodiment of the present invention includes a single crystal silicon substrate having the first conductivity type, an oxide film provided in contact with the light incident side surface of the semiconductor substrate, and in contact with the oxide film. A first amorphous film having a first conductivity type and a second conductivity type opposite to the first conductivity type provided on the opposite side of the light incident side surface of the semiconductor substrate. The second amorphous film is provided adjacent to the second amorphous film in the in-plane direction of the semiconductor substrate on the side opposite to the light incident surface of the semiconductor substrate, and has a first conductivity type. And an amorphous film.

  In the first embodiment, the photoelectric conversion element 100A including the i-type amorphous films 51 to 5m disposed between the n-type single crystal silicon substrate 1 and the p-type amorphous films 11 to 1m, n Photoelectric conversion element 100B including i-type amorphous films 61-6m-1 disposed between n-type single crystal silicon substrate 1 and n-type amorphous films 21-2m-1, and n-type single crystal silicon substrate 1 and p-type amorphous films 11 to 1m, i-type amorphous films 51 to 5m, n-type single crystal silicon substrate 1 and n-type amorphous films 21 to 2m-1 The photoelectric conversion element 100 </ b> C including the i-type amorphous films 61 to 6 m−1 disposed therebetween has been described.

  Further, in the second embodiment, the photoelectric conversion element 200A, p including the i-type amorphous films 151 to 15m disposed between the p-type single crystal silicon substrate 101 and the n-type amorphous films 111 to 11m. Photoelectric conversion element 200B including i-type amorphous films 161-16m-1 disposed between p-type single crystal silicon substrate 101 and p-type amorphous films 121-12m-1, and p-type single crystal silicon substrate 101 and i-type amorphous films 151 to 15m disposed between n-type amorphous films 111 to 11m, p-type single crystal silicon substrate 101, and p-type amorphous films 121 to 12m-1. The photoelectric conversion element 200 </ b> C including the i-type amorphous films 161 to 16 m-1 disposed therebetween has been described.

  Therefore, the photoelectric conversion element according to the embodiment of the present invention includes a single crystal silicon substrate having the first conductivity type, an oxide film provided in contact with the light incident side surface of the semiconductor substrate, and in contact with the oxide film. A first amorphous film having a first conductivity type and a second conductivity type opposite to the first conductivity type provided on the opposite side of the light incident side surface of the semiconductor substrate. The second amorphous film is provided adjacent to the second amorphous film in the in-plane direction of the semiconductor substrate on the side opposite to the light incident surface of the semiconductor substrate, and has a first conductivity type. And an amorphous film having an i-type conductivity type provided between the single crystal silicon substrate and at least one of the second and third amorphous films. . When an amorphous film having i-type conductivity is provided between the single crystal silicon substrate and both the second and third amorphous films, the amorphous film having i-type conductivity is provided. Is provided between the single crystal silicon substrate and the second amorphous film, and has a fourth amorphous film having i-type conductivity, a single crystal silicon substrate, and a third amorphous film. And a fifth amorphous film having i-type conductivity.

  Furthermore, the method for manufacturing the photoelectric conversion element according to the embodiment of the present invention includes a step of forming the oxide film 2 (or oxide film 102) in contact with the light incident side surface of the single crystal silicon substrate, and the oxide film 2 (or After the step of forming the oxide film 102), the p-type amorphous film 11-1m, the n-type amorphous film 3, 21-2m-1, the antireflection film 4 and the electrodes 31-3m, 41-4m-1 ( Or an n-type amorphous film 111-11m, a p-type amorphous film 103, 121-12m-1, an antireflection film 104, and electrodes 131-13m, 141-14m-1). That's fine.

  Therefore, the method for manufacturing the photoelectric conversion element according to the embodiment of the present invention includes the first step of forming an oxide film in contact with the light incident side surface of the semiconductor substrate made of single crystal silicon having the first conductivity type. After the first step, a second step of depositing a first amorphous film having the first conductivity type in contact with the oxide film, and after the first step, on the light incident side of the semiconductor substrate A third step of depositing a second amorphous film having a second conductivity type opposite to the first conductivity type on the side opposite to the surface; and a second amorphous film in an in-plane direction of the semiconductor substrate And a fourth step of depositing a third amorphous film having the first conductivity type on the opposite side of the light incident surface of the semiconductor substrate.

  In the first embodiment, the first conductivity type is n-type, and the second conductivity type is p-type. In the second embodiment, the first conductivity type is p-type, and the second conductivity type is n-type.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The present invention is applied to a photoelectric conversion element and a manufacturing method thereof.

  1 n-type single crystal silicon substrate, 2,102 oxide film, 11-1m, 20, 121-12m-1 p-type amorphous film, 21-2m-1, 40, 111-11m n-type amorphous film, 30, 50 resist pattern, 31-3m, 41-4m-1, 131-13m, 141-14m-1 electrode, 100, 100A, 100B, 100C, 200, 200A, 200B, 200C, 200C photoelectric conversion element, 51- 5m, 61-6m-1, 151-15m, 161-16m-1 i-type amorphous film, 101 p-type single crystal silicon substrate.

Claims (13)

A semiconductor substrate made of single crystal silicon having a first conductivity type;
An oxide film provided in contact with the light incident surface of the semiconductor substrate;
A first amorphous film provided in contact with the oxide film and having the first conductivity type;
A second amorphous film provided on the opposite side of the light incident surface of the semiconductor substrate and having a second conductivity type opposite to the first conductivity type;
A third amorphous material having the first conductivity type, which is provided adjacent to the second amorphous film in the in-plane direction of the semiconductor substrate, on the opposite side of the light incident surface of the semiconductor substrate. A photoelectric conversion element comprising a film.   The photoelectric conversion element according to claim 1, further comprising a fourth amorphous film that is provided between the semiconductor substrate and the second amorphous layer and has an i-type conductivity type.   The photoelectric conversion element according to claim 1, further comprising a fourth amorphous film that is provided between the semiconductor substrate and the third amorphous layer and has an i-type conductivity type.   The fourth amorphous film is any one of i-type amorphous silicon carbide, i-type amorphous silicon nitride, i-type amorphous silicon carbon nitride, i-type amorphous silicon oxide, i-type amorphous silicon, and i-type amorphous silicon germanium. The photoelectric conversion element according to claim 2, comprising: A fourth amorphous film provided between the semiconductor substrate and the second amorphous layer and having i-type conductivity;
The photoelectric conversion element according to claim 1, further comprising a fifth amorphous film that is provided between the semiconductor substrate and the third amorphous layer and has an i-type conductivity type.   Each of the fourth and fifth amorphous films includes i-type amorphous silicon carbide, i-type amorphous silicon nitride, i-type amorphous silicon carbon nitride, i-type amorphous silicon oxide, i-type amorphous silicon, and i-type amorphous. The photoelectric conversion element according to claim 5, comprising any one of silicon germanium.   The photoelectric conversion element according to claim 1, wherein the oxide film is a natural oxide film. The semiconductor substrate is made of n-type single crystal silicon,
The first amorphous film is an n-type amorphous film,
The second amorphous film is a p-type amorphous film,
The photoelectric conversion element according to claim 1, wherein the third amorphous film is an n-type amorphous film. The first amorphous film includes n-type amorphous silicon carbide, n-type amorphous silicon nitride, n-type amorphous silicon carbon nitride, n-type amorphous silicon oxide, n-type amorphous silicon, n-type amorphous silicon germanium, and n-type. Made of either amorphous germanium,
The second amorphous film includes p-type amorphous silicon carbide, p-type amorphous silicon nitride, p-type amorphous silicon carbon nitride, p-type amorphous silicon oxide, p-type amorphous silicon, p-type amorphous silicon germanium, and p-type. Made of either amorphous germanium,
The third amorphous film includes n-type amorphous silicon carbide, n-type amorphous silicon nitride, n-type amorphous silicon carbon nitride, n-type amorphous silicon oxide, n-type amorphous silicon, n-type amorphous silicon germanium, and n-type. The photoelectric conversion element according to claim 8, comprising any one of amorphous germanium. The semiconductor substrate is made of p-type single crystal silicon,
The first amorphous film is a p-type amorphous film,
The second amorphous film is an n-type amorphous film,
The photoelectric conversion element according to any one of claims 1 to 7, wherein the third amorphous film is a p-type amorphous film. The first amorphous film includes p-type amorphous silicon carbide, p-type amorphous silicon nitride, p-type amorphous silicon carbon nitride, p-type amorphous silicon oxide, p-type amorphous silicon, p-type amorphous silicon germanium, and p-type. Made of either amorphous germanium,
The second amorphous film includes n-type amorphous silicon carbide, n-type amorphous silicon nitride, n-type amorphous silicon carbon nitride, n-type amorphous silicon oxide, n-type amorphous silicon, n-type amorphous silicon germanium, and n-type. Made of either amorphous germanium,
The third amorphous film includes p-type amorphous silicon carbide, p-type amorphous silicon nitride, p-type amorphous silicon carbon nitride, p-type amorphous silicon oxide, p-type amorphous silicon, p-type amorphous silicon germanium, and p-type. The photoelectric conversion element according to claim 10, comprising any of amorphous germanium. A first step of forming an oxide film in contact with the light incident surface of a semiconductor substrate made of single crystal silicon having a first conductivity type;
A second step of depositing a first amorphous film having the first conductivity type in contact with the oxide film after the first step;
After the first step, a third amorphous film having a second conductivity type opposite to the first conductivity type is deposited on the opposite side of the light incident side surface of the semiconductor substrate. Process,
A third amorphous film having the first conductivity type is deposited on the opposite side of the light incident side surface of the semiconductor substrate adjacent to the second amorphous film in the in-plane direction of the semiconductor substrate. A manufacturing method of a photoelectric conversion element provided with the 4th process to do.   13. The photoelectric conversion element according to claim 12, wherein in the first step, the oxide film is formed by any one of a chemical deposition method, a thermal oxidation method, a wet oxidation method, an underwater oxidation method, and a natural oxidation method. Production method.

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