JP2003253435A - Method of depositing rugged film and method of manufacturing photoelectric converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of depositing a rugged film by which the rugged film is formed under a low temperature condition. <P>SOLUTION: A source material of a 1st transparent conductive film 32 is evaporated by an evaporation system in a vacuum chamber where the temperature and the pressure of an atmosphere is set to a proper value, is grown into particles 32a having a proper size before the source material reaches a glass substrate 30 and is deposited on the substrate 30. After the deposition of the particles 32a, the source material is deposited on the substrate 30 to fill the gap among the particles 32a as particles (including molecules) having a size smaller than that of the particles 32a by lowering the temperature and the pressure. As a result, the 1st transparent conductive film 32 having ruggedness is deposited. A photoelectric converter is formed by successively stacking a photoelectric conversion film 33, a 2nd transparent conductive film 34 and a reflection film 35 on the 1st transparent conductive film 32. Because the particles 32a are grown before the particles 32a reach the substrate 30, it is unnecessary to make the temperature of the substrate 30 high. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for forming a concavo-convex film on a substrate or a semiconductor element, a method for manufacturing a photoelectric conversion element,
And a photoelectric conversion element.

[0002]

2. Description of the Related Art In photoelectric conversion elements such as solar cells and photodetectors, in order to increase the efficiency of use of light incident on the element, unevenness is formed on the element and the unevenness scatters light to increase the optical path length. Alternatively, the reflected light is used again for photoelectric conversion.

Conventionally, as a method of forming such unevenness on an element, there is a method of growing a film having unevenness (an uneven film) on a substrate by utilizing crystal growth by a thin film forming method such as a thermal CVD method. Was used.

[0004]

Therefore, in the conventional formation of the concavo-convex film, it is necessary to raise the temperature of the substrate (several hundred degrees to one thousand and several hundred degrees, etc.). Therefore, the material used for the substrate and the kind of the substrate are used. Was limited in its ability to withstand high temperatures.

Further, since a high temperature is required to form the uneven film, it is difficult to form an uneven film (for example, a transparent conductive film having unevenness) on the photoelectric conversion film whose performance deteriorates at high temperature. . Similarly, the uneven film could not be formed on the already manufactured photoelectric conversion element.

On the other hand, as a method of forming the uneven film without raising the temperature, a method of mechanically scraping the surface of the substrate or using etching is conceivable. In such a method, the CVD method and the vapor deposition method are used. A process different from the manufacturing process of the photoelectric conversion element, which uses the sputtering method, the sputtering method, etc., is required, which requires cost and time.

Further, when the transparent conductive film of the photoelectric conversion element is formed as an uneven film, since the film forming conditions have an appropriate range, the conventional uneven film manufacturing method has an appropriate unevenness characteristic and electrical and optical characteristics. It was difficult to satisfy the characteristics at the same time.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for manufacturing a concavo-convex film which enables the concavo-convex film to be formed under low temperature conditions.

[0009]

In order to achieve the above object, in the method for forming a concavo-convex film according to the first aspect of the present invention, particles serving as the core of the concavo-convex film are first grown and then adhered to a substrate or the like after the growth. After that, the uneven film is formed by filling the space between the adhered particles with particles smaller than the particles (including molecular and atomic particles).

That is, the method for forming a concavo-convex film according to the first aspect of the present invention is a method for forming a film having concavities and convexities on a substrate or a semiconductor element, wherein a material for forming the film having concavities and convexities is first formed. A first step of growing the first particles, a second step of adhering the first particles to the substrate or the semiconductor element after the substance has grown to the first particles, and the first particles A third step of adhering smaller second particles of the substance to the substrate or the semiconductor element or the first particles attached to the substrate or the semiconductor element.

Here, the second particles include molecules, atoms, and particles in which a plurality of these molecules or atoms are combined,
Further, those molecules, atoms, or particles in which a plurality of molecules or atoms are bonded are electrically charged, and the like.

According to the first aspect of the present invention, after the formation of the first particles, the first particles adhere to the substrate or the semiconductor device. After that, a second particle smaller than the first particle
The unevenness film is formed by adhering and depositing on the substrate or the like so as to fill the spaces between the first particles. As described above, since particles are not grown on the substrate or the semiconductor element, it is not necessary to raise the temperature of the substrate or the like. Thereby, the selection range of the substrate and the like is widened, and the uneven film can be formed on the photoelectric conversion film or the photoelectric conversion element having the photoelectric conversion film whose performance is deteriorated at high temperature without deteriorating the performance.

Further, according to the first aspect of the present invention, the uneven film can be formed by the same process as the manufacturing process of the photoelectric conversion element.

In one embodiment, the first step is a step of evaporating by heating the substance by an evaporation device, the evaporation device, and the substrate arranged apart from the evaporation device. Growing the substance into the first particle by utilizing collision and binding of the vaporized substance in a space between the substance and the semiconductor device.

Preferably, the third step is carried out by heating and vaporizing the substance by the evaporator, and after the second step, both the heating temperature of the evaporator and the pressure of the atmosphere or The third step is performed by reducing one. Thus, the uneven film can be formed by simply changing the temperature or the pressure in the same device.

In the method for manufacturing a photoelectric conversion element according to the second aspect of the present invention, a substance having a light-transmitting property is grown into first particles, and then the first particles are transferred to one of the substrates having a light-transmitting property. And then attach second particles smaller than the first particles and made of the substance to one surface of the substrate or the first particles attached to one surface of the substrate. Then, a light-transmitting uneven film is formed, and a light-transmitting conductive film, a photoelectric conversion film, and a conductive film are sequentially stacked on the formed uneven film.

In the method for manufacturing a photoelectric conversion element according to the second aspect of the present invention, a conductive material having a light-transmitting property is grown into first particles, and then the first particles have a light-transmitting property. The first particles adhered to one surface of the substrate and then the second particles of the conductive material smaller than the first particles adhered to one surface of the substrate or one surface of the substrate. To form a light-transmitting conductive film having unevenness on the particles, and on the formed light-transmitting conductive film having unevenness,
It is formed by sequentially stacking a photoelectric conversion film and a conductive film.

Further, in the method for manufacturing a photoelectric conversion element according to the second aspect of the present invention, the first transparent conductive film and the photoelectric conversion film are sequentially laminated on one surface of the substrate having a light transmitting property. After forming and growing a light-transmitting conductive material on the first particles, the first particles are attached to the photoelectric conversion film, and then the conductive material smaller than the first particles is used. The second particles are attached to the photoelectric conversion film or the first particles attached to the photoelectric conversion film to form a second translucent conductive film having irregularities.

Here, the "conductive film" may be a conductive film having a light-transmitting property (light-transmitting conductive film) or a conductive film having no light-transmitting property. When the conductive film is a translucent conductive film, a reflective film may be further laminated on the conductive film.

According to the second aspect of the present invention, the uneven film can be formed on the substrate having a low temperature. Therefore, the concavo-convex film can be formed on the photoelectric conversion film whose performance deteriorates at high temperature without deteriorating the performance.

The size of the first particles can be controlled by adjusting the temperature or pressure of the atmosphere in which the first particles are grown, and as a result, the degree of unevenness of the uneven film can also be controlled. As a result, when the transparent conductive film is formed as an uneven film, it is possible to satisfy appropriate unevenness characteristics and electrical and optical characteristics at the same time.

Preferably, in the method for producing a photoelectric conversion element according to the second aspect of the present invention, the average diameter of the first particles is
The size of the range in which the incident light can be reflected in a direction different from the incident direction, and the size of the range in which the incident light can be attached,
The first particles are grown, and specifically,
The first particles have an average diameter of 0.05 μm to 1
It grows up to the range of μm.

According to a third aspect of the present invention, there is provided a method of manufacturing a photoelectric conversion element, wherein a transparent conductive film is formed on one surface of a transparent substrate,
A photoelectric conversion film and a conductive film are sequentially laminated to form a concavo-convex film made of a substance having a photocatalytic action before, after, or during the formation of the translucent conductive film, the photoelectric conversion film, and the conductive film. It is formed on the other surface of the substrate.

The photoelectric conversion element according to the third aspect of the present invention is a translucent substrate, a translucent conductive film formed on one surface of the translucent substrate, and a translucent conductive film on the translucent conductive film. A photoelectric conversion film formed on the photoelectric conversion film, a conductive film formed on the photoelectric conversion film, and a concavo-convex film formed on the other surface of the translucent substrate and made of a substance having a photocatalytic action. .

According to the third aspect of the present invention, since the concavo-convex film made of a substance having a photocatalytic action removes stains on the other surface of the substrate, it is possible to prevent the incident amount of light from being reduced by the stains. In addition, since the substance having a photocatalytic action is formed as a concavo-convex film, the concavo-convex portion can be optically viewed as a mixture of the film material and air by adjusting the degree of the concavo-convex film. The refractive index can be lowered. As a result, the amount of light reflected by the concavo-convex film made of a substance having a photocatalytic action can be reduced and the amount of light incident on the photoelectric conversion film can be increased.

In order to obtain such a concavo-convex film for lowering the refractive index, the film thickness difference between the concave and convex portions of the concavo-convex film is 0.2 μm.
The following is preferable.

Without raising the temperature of the transparent substrate,
In order to form a concavo-convex film of a substance having a photocatalytic action, a concavo-convex film made of the substance having a photocatalytic action is grown on the third particles after the substance having a photocatalytic action is grown on the third particle.
Particles are attached to the other surface of the translucent substrate, and then fourth particles of a substance having the photocatalytic action smaller than the third particles are attached to the other surface of the translucent substrate or the It is preferably formed by adhering to the third particles attached to the other surface.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION <Structure of Semiconductor Manufacturing Device (Concave / Concave Film Manufacturing Device)> FIG. 1 is a schematic structural diagram of a semiconductor manufacturing device (irregular film manufacturing device) 10 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the substrate 20 on which the uneven film is formed according to the embodiment of the present invention.

The semiconductor manufacturing apparatus 10 has a vacuum container 11, an evaporator 12, an RF antenna 13, a gas supply passage 14, an exhaust port 15, and an exhaust pump 16.

A substrate 20 is attached inside the vacuum container 11. As the substrate 20, for example, in addition to glass (silicon dioxide (SiO ₂ )), plastic having a relatively low softening point, PET (polyethylene terephthalate)
Etc. can be used. The substrate 20 is the evaporator 12
In order to make it easier for substances evaporated from the
Is preferably arranged vertically above.

A heating device (not shown) is attached to the substrate 20, and the substrate 20 is brought to a predetermined temperature described later by the heating device. Radiant heating, contact heating, or the like can be used as the heating device.

The evaporation device 12 has an evaporation crucible (crucible) and a heating device for the evaporation crucible, which are not shown. As a heating device for the evaporation crucible, a resistance heating device, a plasma heating device,
An electron beam heating device or the like can be used, but a resistance heating device (for example, an electric heater or the like) is preferable because the evaporation crucible and its surroundings are placed under high pressure in order to form particles that form the core of the uneven film. . This resistance heating device is, for example, integrated with an evaporation crucible.

The RF antenna 13 is arranged between the evaporator 12 and the substrate 20. The RF antenna 13 has, for example, a ring shape or a spiral shape. A high-frequency (for example, 13.56 MHz) electric signal is applied to the RF antenna 13 from a high-frequency signal generator (not shown), whereby the RF antenna 13 generates plasma around it. By generating this plasma, the characteristics (translucency, adhesion, etc.) of the uneven film can be improved.

The gas supply passage 14 is a passage for supplying gas from a gas supply source (not shown). The supplied gas is, for example, oxygen gas (O ₂ ) for oxidizing the substance in the evaporator 12. Further, an inert gas such as argon (Ar) or xenon (Xe) may be mixed in order to adjust the concentration of oxygen gas. The gas flow rate is adjusted by a gas supply device (not shown). Gas supply path 1
The outlet of No. 4 is preferably arranged in the vicinity of the evaporator 12 in order to enhance the efficiency of oxidizing the evaporated substance by the evaporator 12.

The exhaust device 16 sucks the gas in the vacuum container 11 through the exhaust port 15 and exhausts it. The evacuation device 16 has a sensor (not shown) that detects the internal pressure of the vacuum container 11 so that the internal pressure of the vacuum container 11 becomes a target pressure based on the internal pressure detected by the sensor. ， Adjust the amount of exhaust gas. The exhaust port 15 is provided so as not to prevent the oxide from adhering to the substrate 20.
It is preferable that the substrate 20 is arranged at the opposite position with the evaporator 12 interposed therebetween.

<Manufacturing Method of Uneven Film> Semiconductor manufacturing apparatus 10
A method of manufacturing the uneven film made of tin dioxide (SnO ₂ ) will be described with reference to FIG.

A glass substrate is used as the substrate 20.
Tin monoxide (SnO) is put into the evaporation crucible of the evaporation device 24, and the temperature of the evaporation crucible is adjusted to about 1200 ° C. The pressure in the vacuum container 11 is about 5 Pa. The pressure of the oxygen gas supplied from the gas supply passage 14 is about 100 Pa. Board 2
A temperature of 0 is about 1 to promote evaporation of water on the substrate surface.
Set to 00 ° C.

The tin monoxide particles evaporated from the evaporation crucible react with oxygen gas to become tin dioxide (SnO ₂ ), and repeatedly collide many times before reaching the substrate 20 to form fine particles. Tin dioxide fine particles grow to a size of about 50 nm to 100 nm under this condition. The formed fine particles reach and adhere to the surface of the substrate 20 (fine particles 21a in FIG. 2).

After this state is continued for about 20 seconds, the temperature of the evaporation crucible is set to 600 ° C. and the vacuum container 11 is filled in several minutes in order to fill the space between the adhered fine particles 21a and form the uneven film 21.
The internal pressure is reduced to 0.1 Pa. As a result, the evaporation amount of tin dioxide is reduced and the number of collisions of the evaporated material is reduced, so that tin dioxide reaches the surface of the substrate 20 in the state of particles or molecules smaller than the fine particles 21a, and the fine particles of the substrate 20. It is deposited between 21a. as a result,
The uneven film 21 that is smooth and has unevenness of about the diameter of the fine particles 21a is obtained. At this time, the average film thickness of the uneven film 21 was about 100 nm to 150 nm, and the haze ratio of 43% could be obtained.

Pressure in the vacuum vessel 21 and evaporation device 24
By controlling both or one of the heating temperatures, the size of the fine particles can be changed appropriately, and as a result, the change in the unevenness of the uneven film 21 can also be adjusted. In addition, the plasma is generated by the RF antenna 13 to accelerate the reaction of the fine particles and charge the fine particles to the substrate 2
It is also possible to strongly adhere to 0.

The temperature of the evaporation crucible at the time of growing and adhering the fine particles 21a was 1200 ° C., but this temperature is in the range of 700 ° C. to 2000 ° C., preferably 100 ° C.
It may be in the range of 0 ° C to 1200 ° C. Further, the high frequency power of the RF antenna 13 may be 1 W or more, but 10 W
To 200 W is preferred. The film formation time was 20 seconds, but it changes depending on the progress of the surface coverage of the fine particles.

After forming the fine particles, the temperature of the evaporation crucible when forming the uneven film 21 was set to 600 ° C.
It may be in the range of 500 ° C to 1000 ° C, preferably in the range of 570 ° C to 680 ° C.

The temperature of the substrate 20 may be lower than 100 ° C. depending on the material used. As described above, according to the present embodiment, the temperature of the substrate 20 can be set to a low temperature, so that the selection range of the material used for the substrate 20 and the type of the substrate is widened. Further, since the uneven film 21 can be formed by the same process as the manufacturing of the photoelectric conversion element described later, the cost and time required for forming the uneven film can be reduced.

<Method for Manufacturing Photoelectric Conversion Element> A photoelectric conversion element (for example, solar cell, light receiving element, etc.) can be formed by laminating a photoelectric conversion film (power generation film) or the like on the uneven film formed on the substrate. . FIG. 3 is a sectional view showing the configuration of the photoelectric conversion element 3 according to the embodiment of the present invention.

The photoelectric conversion element 3 includes a substrate 30, an uneven film 31 sequentially laminated on the substrate 30, a first transparent conductive film (translucent conductive film) 32, a photoelectric conversion film (power generation film) 3
3, a second transparent conductive film (translucent conductive film) 34, and a reflective film (back electrode film) 35. In FIG. 3, the scales of the film thicknesses are not the same in order to make the diagram easy to understand.

The substrate 30 is a flat glass substrate (soda glass or the like) that transmits light. The uneven film 31 is made of silicon dioxide as a raw material. The average film thickness of the uneven film 31 is preferably 0.5 times or more the average diameter of the fine particles 31a, and is, for example, 100 nm to 150 nm.

The uneven film 31 is the uneven film 21 of FIG.
In the same manner as above, it is formed on the substrate 30 by the semiconductor manufacturing apparatus 10. However, since the concavo-convex film 31 is formed of silicon dioxide, the evaporation device 12 (evaporation crucible) contains, for example, SiO ₂ granules, and the temperature of the evaporation crucible is about 15
Set to 00 ° C. The reference numeral 31a indicates the uneven film 31.
Of silicon dioxide, which is the nucleus of (a unitary with the uneven film 31).

After the uneven film 31 is formed, the first transparent conductive film 32, the photoelectric conversion film (power generation film) 33, the second transparent conductive film 34, and the reflective film 35 are sequentially formed. The forming method is as follows.

First, the temperature of the substrate 30 on which the uneven film 31 is formed is heated to 450.degree. And tin tetrachloride (Sn
Cl ₄ ), water (H ₂ O), and hydrogen fluoride (HF) are sprayed onto the substrate 30 from different nozzles by a thermal CVD method to form a first transparent conductive film 32 made of tin dioxide on the uneven film 31. About 800 nm. Since the first conductive film 32 is deposited on the uneven film 31, the first transparent conductive film 32 having smooth unevenness that reflects the unevenness of the uneven film 31 can be obtained.

Next, the frequency 13.
A photoelectric conversion film (amorphous silicon semiconductor layer) 33 including a p-type layer, an i-type layer and an n-type layer is formed by a vapor phase growth method using a high frequency discharge of 56 MHz. This photoelectric conversion film 3
The film thickness of 3 (that is, the total film thickness of the p-type layer, the i-type layer, and the n-type layer) is, for example, about 0.3 μm.

Here, monosilane is used to form the p-type layer.
(SiH_Four), Diborane (B₂H₆), And hydrogen (H₂)
Was used as the source gas. Methane if needed
(CH_Four) Can also be added. To form the n-type layer,
Monosilane, phosphine (PH ₃), And hydrogen
Used as feed gas. Monosilane was used to form the i-type layer.
It was used as a raw material gas. If necessary, add hydrogen
You can

Then, a second transparent conductive film 34 (film thickness of about 0.1 μm) is formed by using the sputtering method or the like. Finally, as the reflection film 35, for example, aluminum (Al) is used.
A film is formed with a film thickness of about 0.5 μm by using a vapor deposition method or the like. As a result, the photoelectric conversion element 3 is formed.

In this way, the film 3 is sequentially formed on the uneven film 31.
Since the films 2 to 35 are formed, the films 32 to 35 are all formed as smooth uneven films. As a result, the light incident from above the substrate 30 passes through the substrate and the uneven film 31, and the boundary between the uneven film 31 and the first transparent conductive film 32, and the first transparent conductive film 32 and the photoelectric conversion film. The light is scattered at the boundary with the film 33, enters the photoelectric conversion film 33 as light in random directions, and is converted into electricity.

The light that is not absorbed by the photoelectric conversion film 33 (that is, the light that is not converted into electricity) is generated at the boundary between the photoelectric conversion film 33 and the second transparent conductive film 34, and at the second
Is reflected at the boundary between the transparent conductive film 34 and the reflective film 35 and again enters the photoelectric conversion film 33 as light in random directions,
Converted to electricity. This electricity is generated by the first transparent conductive film 32.
, And the second transparent conductive film 34 (and the reflective film 35), to a power output terminal (not shown). In this way, the incident light is scattered or reflected by the boundary of each film and enters the photoelectric conversion film 33, so that the photoelectric conversion film 33
The utilization efficiency of light in is improved.

The method of manufacturing each of the films 32 to 35 is an example, and other manufacturing methods can be used. For example, the first transparent conductive film 32 can also be formed by a sputtering method.

In the formation of the first conductive film 32,
The substrate 30 having the uneven film 31 is set to 450 ° C.,
By using another manufacturing method (for example, a sputtering method) for forming the first conductive film 32, the temperature is lower than 100 ° C.
The first conductive film 32 can also be formed at a temperature of about the same or lower. Therefore, the photoelectric conversion element 3 can be manufactured even when a material such as resin (PET or the like) having a low softening point is used for the substrate 30.

Further, the reflection film 35 may not be provided, and when the reflection film 35 is also used as a conductive film, the second transparent conductive film 34 may not be provided.
The same applies to photoelectric conversion elements 4 and 6 described below.

<Photoelectric Conversion Element Using Transparent Conductive Film as Concavo-Convex Film> The first transparent conductive film itself forming the photoelectric conversion element may be formed as an uneven film. FIG. 4 is a cross-sectional view showing the configuration of the photoelectric conversion element 4 in which the first transparent conductive film is formed as an uneven film. The same components as those of the photoelectric conversion element 3 in FIG. 3 are designated by the same reference numerals.

The photoelectric conversion element 4 has a substrate 30, a first transparent conductive film 32, a photoelectric conversion film (power generation film) 33, a second transparent conductive film 34, and a reflective film 35. Fig. 4
However, the scale of each film thickness is not the same.

The first transparent conductive film 32 containing fine particles 32a of tin dioxide (which is integrated with the first transparent conductive film 32) is formed on the substrate 30 by the same manufacturing method as that for the uneven film 21 described above. The average thickness of the first transparent conductive film 32 is
As described above, the average diameter of the fine particles 32a is preferably 0.5 times or more, and is about 1 μm here.

After that, the photoelectric conversion film (amorphous silicon semiconductor layer) 33, the second transparent conductive film 34, and the reflective film 35 are formed by the same method as described above. As a result, the photoelectric conversion element 4 is formed.

The photoelectric conversion element 4 also improves the light utilization efficiency in the photoelectric conversion film 33, similarly to the photoelectric conversion element 3 described above. In the photoelectric conversion element 4, the first
Since the conductive film 31 is also used as an uneven film, the manufacturing process of the photoelectric conversion element can be simplified, and the manufacturing cost and time can be reduced.

Further, in the conventional method of forming a concavo-convex film, it was necessary to raise the temperature of the substrate as described in the section of the conventional technique. Therefore, it is difficult to realize a film having appropriate unevenness on a high temperature substrate, having a low electric resistance which is a necessary condition for a transparent conductive film, and having a high light transmittance. However, according to the present embodiment, since the transparent conductive film can be formed as a concavo-convex film even when the substrate 30 is at a relatively low temperature, it has appropriate concavities and convexities, low electrical resistance, and high light transmittance. It is possible to form a transparent conductive film having the same.

<Photoelectric conversion element using a transparent conductive film on the back surface as an uneven film> The second transparent conductive film formed on the back surface can also be formed as an uneven film. FIG. 5 is a cross-sectional view showing the configuration of the photoelectric conversion element 5 in which the second transparent conductive film is formed as an uneven film. The same components as those of the photoelectric conversion element 3 in FIG. 3 are designated by the same reference numerals.

The photoelectric conversion element 5 has a substrate 30, a first transparent conductive film 32, a photoelectric conversion film (power generation film) 33, a second transparent conductive film 34, and a reflective film 35. Fig. 5
However, the scale of each film thickness is not the same.

The first transparent conductive film 32 and the photoelectric conversion film 33 are sequentially formed on the substrate 30 by the same method as that of the photoelectric conversion element 3 (FIG. 3) described above. Next, by the same method as that for the uneven film 21 of FIG.
The second transparent conductive film 34, which is integrated with the transparent conductive film 34) of
The average film thickness is formed. After that, the reflection film 35 is formed by a vapor deposition method or the like. As a result, the photoelectric conversion element 5 is formed.

In this way, the uneven film can be formed while the substrate is kept at a relatively low temperature. Therefore, even if the uneven film is formed after the photoelectric conversion film 33 is formed, the performance of the photoelectric conversion film 33 is not deteriorated.

In this photoelectric conversion element 5, light incident from the substrate 30 (above the drawing) is transmitted through the first transparent conductive film 32 and converted into electricity by the photoelectric conversion film 33. Of the incident light, the light not absorbed by the photoelectric conversion film 33 mainly includes the interface between the photoelectric conversion film 33 and the second transparent conductive film 34, and the second transparent conductive film 34 and the reflective film. The light is reflected at the interface with 35 and again enters the photoelectric conversion film 33 to be converted into electricity. This electricity is output to a power output terminal (not shown) through the first transparent conductive film 32 and the second transparent conductive film 34 (and the reflective film 35).

In the photoelectric conversion element 5, since the concavo-convex film (second transparent conductive film 34) is formed on the back surface (upper part) of the photoelectric conversion film 33, the photoelectric conversion film 33 itself has a flat surface with a small concavo-convex shape. Substrate 30 (and first transparent conductive film 32)
Can be formed on. Therefore, the photoelectric conversion film 3
The film quality of No. 3 can be made uniform. as a result,
When the photoelectric conversion film 33 is formed on the concavo-convex film (that is, when the photoelectric conversion film 33 itself has a concavo-convex shape), the photoelectric conversion efficiency is deteriorated due to deterioration of the film quality of the photoelectric conversion film,
It is possible to prevent a decrease in open circuit voltage due to non-uniformity of film quality and a decrease in photoelectric conversion efficiency due to a decrease in form factor.

The photoelectric conversion film 32 has a wavelength characteristic that the absorption coefficient of long-wavelength light is low. Therefore, long-wavelength light is not absorbed by the photoelectric conversion film 33 and is transmitted to the second transparent conductive film 34 side. The transmitted light is photoelectric conversion film 3
Part of the light is reflected at the interface between the third transparent conductive film 34 and the third transparent conductive film 34, but most of the light is transmitted through the interface and the second transparent conductive film 34. The transmitted light is reflected at the interface between the second transparent conductive film 34 and the reflective film 35. At this time, since the second transparent conductive film 34 contains the fine particles 34a in the film, the surface shape thereof has unevenness of about the diameter of the fine particles 34a. Therefore, the light reflected at the interface between the second transparent conductive film 34 and the reflective film 35 is highly likely reflected in a direction different from the incident light.

Therefore, for example, the vertically incident light is obliquely reflected at the interface between the second transparent conductive film 34 and the reflective film 35 and re-enters the photoelectric conversion film 33, and the optical path length in the photoelectric conversion film 33 is increased. Becomes longer. Further, the light reflected obliquely at a predetermined angle or more becomes a total reflection condition for the light incident from the photoelectric conversion film 33 side at the interface between the photoelectric conversion film 33 and the first transparent conductive film 32, and the photoelectric conversion is performed again. It is reflected in the film 33. This further increases the optical path length. As a result, the probability that light is absorbed by the photoelectric conversion film 33 and converted into electric power is increased, and the short-circuit current is improved.

Here, the unevenness of the second transparent conductive film 34 formed on the back surface has a low oblique reflectance unless it is appropriately large with respect to the wavelength of the incident light. Therefore, the fine particles 34
The average diameter D of a may be 50 nm or more, but it is preferable that the optical thickness of the photoelectric conversion film 33 (amorphous silicon in this case) is higher than the optical wavelength of λ = 500 nm. Is 0.5 times or more. That is, n
Is the refractive index of the second transparent conductive film 34, the diameter D is
It is preferable that λ / (2n) = 500 / (2 × 2) = 125 nm or more.

On the other hand, if the diameter of the fine particles 34a becomes too large, it becomes technically difficult to contact the photoelectric conversion film 33 and the second transparent conductive film 34. Therefore, the average diameter D is preferably 1 μm or less. Therefore, 50 nm ≦ D ≦ 1 μm, preferably 125 nm ≦ D ≦ 1 μm.

For the same reason, the surface coverage of the fine particles 34a is preferably in the range of 0.01-1.

The range of the average diameter D and the range of the surface coverage can be applied to the photoelectric conversion elements 3 and 4 described above.

<Application to Crystalline Photoelectric Conversion Element> In the above-described embodiments, the photoelectric conversion film 33 is formed as an amorphous semiconductor film. However, the photoelectric conversion film 33 is made of a crystalline material (single crystal, polycrystal). It can also be formed by crystals or microcrystals.

That is, although the crystalline material has a small absorption coefficient of sunlight, the photoelectric conversion elements 3 to 5 and the photoelectric conversion element 5, particularly the photoelectric conversion element 5 having the uneven film formed as described above, have a remarkable light confining effect. Therefore, the photoelectric conversion efficiency can be improved even in the photoelectric conversion element using the crystalline material.

<Photoelectric Conversion Device with Photocatalyst Film> Titanium dioxide (TiO ₂ ), nickel oxide (NiO _x ), etc. (especially nickel dioxide (NiO ₂ )) is a material having a photocatalytic action on the surface of the photoelectric conversion device (light incident surface). It can also be applied to.

FIG. 6 is a sectional view showing the structure of a photoelectric conversion element 6 in which a titanium dioxide film is attached to a substrate as an uneven film. The same components as those of the photoelectric conversion element 3 in FIG. 3 are designated by the same reference numerals.

The photoelectric conversion element 6 has an uneven film 40 of titanium dioxide, a substrate 30, a first transparent conductive film 32, a photoelectric conversion film 33, a second transparent conductive film 34, and a reflective film 35.

The titanium dioxide concavo-convex film 40 is formed on the substrate 30 by the same method as the concavo-convex film 21 (see FIG. 3).
Is formed on the surface (the surface on the side on which light is incident). However,
Since titanium dioxide is used, the temperature of the evaporation crucible is set to about 2200 ° C., which is higher than that of tin oxide. The thickness of the uneven film 40 is, for example, in the range of 0.05 μm to 0.5 μm. Further, the film thickness difference between the convex portion and the concave portion of the uneven film 40 is set to 0.01 μm to 0.2 μm. The reason why the film thickness difference is within such a range will be described later. Reference numeral 40a indicates fine particles of titanium dioxide (integrated with the uneven film 40).

First transparent conductive film 32 and photoelectric conversion film 3
3 is formed as a flat film on the flat back surface of the substrate 30 by the same method as the photoelectric conversion element 5 described above. Also,
The second transparent conductive film 34 and the reflective film 35 are also formed as a flat film on the photoelectric conversion film 33 by the same method as that of the photoelectric conversion element 5 described above.

The uneven film 40 is formed by forming the first transparent conductive film 3
2, before or after the formation of the photoelectric conversion film 33, the second transparent conductive film 34, and the reflective film 35, the first transparent conductive film 32, the photoelectric conversion film 3
It can also be performed during the formation of the third transparent conductive film 34 and the reflective film 35. For example, it can be performed after the formation of the first transparent conductive film 32 and before the formation of the photoelectric conversion film 33.

When a substance having a photocatalytic action such as titanium dioxide or nickel oxide is irradiated with ultraviolet rays, titanium (Ti) atoms and nickel (Ni) atoms in the outermost layer are excited. As a result, as a photocatalytic action, there are effects such as oxidative decomposition of organic matter and improvement of hydrophilicity due to decomposition of water. Therefore, the dirt on the surface of the photoelectric conversion element 6 (the surface of the substrate 30) can be removed. This can prevent a decrease in the amount of light incident on the photoelectric conversion film 33.

Further, such a substance having a photocatalytic action has an optically high refractive index (for example, a refractive index n =
3) The light reflectance is high, but the unevenness of the titanium dioxide film 40 is optically reduced by setting the film thickness difference between the convex and concave portions of the uneven film 40 to 0.2 μm or less. It becomes a mixture of (refractive index n = 1) and film material (n = 3),
It is possible to reduce the effective refractive index.

That is, the wavelength range of visible light is 0.3 μm
If the effective refractive index n of the optical mixture of 0.8 μm of air and the film material is n = (1 + 3) / 2 = 2, the film thickness difference h ≦
If 0.8 μm ÷ (2n) = 0.2 μm, the uneven film 4
0 is a mixture of air and the film material, and the effective refractive index decreases. The lower limit of the film thickness difference of 0.01 μm is for making it difficult for dust and the like to adhere to the surface of the uneven film 40.

Further, according to the method for forming a concavo-convex film according to the present embodiment, the concavo-convex film can be formed at a low substrate temperature, so that the photocatalytic action can be exerted also on the surface of the glass substrate 30 or PET having a relatively low melting point. The uneven film having can be formed.

In the formation of the concavo-convex film according to the present embodiment, the substrate temperature can be set to a low temperature, so that even a photoelectric conversion element on which a photoelectric conversion film has already been formed does not deteriorate the performance of the photoelectric conversion film and has a photocatalytic action. It is possible to form an uneven film having Therefore, the photoelectric conversion elements 3 to 5 described above
The uneven film 40 can be formed on the light incident surface of the substrate 30. Further, for the same reason, the concavo-convex film 40 can be formed on the photoelectric conversion element in which the resin protective film or the like is further formed on the reflective film. It can be formed even for a photoelectric conversion element already used outdoors.

In the above-described embodiments, the uneven film or the first or second transparent electrode film is made of tin dioxide or silicon dioxide, but in addition to this, zinc oxide (ZnO), oxide Indium tin (IT
O), indium oxide (In ₂ O ₃ ) or the like.

[0090]

According to the present invention, the uneven film can be formed even when the temperature of the substrate is low. This expands the selection range of the substrate. Further, the concavo-convex film can be formed also on the semiconductor element on which the functional film such as the photoelectric conversion film has already been formed.

According to the present invention, the uneven film can be formed by the same process as the manufacturing process of the photoelectric conversion element.

According to the present invention, by providing the photoelectric conversion film with the concavo-convex film made of a substance having a photocatalytic action, dirt on the surface of the photoelectric conversion film can be removed, and the substantial refractive index of the substance having a photocatalytic action can be reduced. can do. As a result, the amount of light incident on the photoelectric conversion element can be increased.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a semiconductor manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a substrate on which a concavo-convex film is formed according to an embodiment of the present invention.

FIG. 3 is a sectional view showing a configuration of a photoelectric conversion element according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a configuration of a photoelectric conversion element in which a first transparent conductive film is formed as an uneven film.

FIG. 5 is a cross-sectional view showing a configuration of a photoelectric conversion element in which a second transparent conductive film is formed as an uneven film.

FIG. 6 is a cross-sectional view showing a configuration of a photoelectric conversion element 6 in which a titanium dioxide film is attached to a substrate as an uneven film.

[Explanation of symbols]

10 Semiconductor manufacturing equipment 3,4,5 photoelectric conversion element 20, 30 substrate 21,31 Concavo-convex film 21a, 31a, 34a, 40a Fine particles 32 First transparent conductive film 33 Photoelectric conversion film (power generation film) 34 Second transparent conductive film 35 Reflective film 40 Titanium dioxide uneven film

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4G069 AA02 BA04A BA04B BA13A                       BA13B BA22A BA48A BB04A                       BC68A CA01 CA11 EA07                       EA11 EB03 EB15Y                 4K029 AA09 AA24 BB00 BB02 BC03                       BC09 BD00 BD01 CA01 EA00                       EA03                 4M104 BB36 DD34 GG05                 5F051 AA05 BA13 CA13 CA15 FA02                       FA16 FA19 GA03 GA14 HA20                 5F088 BA20 CA02 CA04 CA10 DA17                       DA20 HA20

Claims (16)

[Claims] 1. A method of forming a film having unevenness on a substrate or a semiconductor device, comprising: a first step of growing a substance for forming the film having the unevenness into first particles; After growing into first particles, the second step of attaching the first particles to the substrate or the semiconductor element, and the second particles smaller than the first particles and made of the substance, And a third step of adhering to the substrate or the semiconductor element, or the first particles attached to the substrate or the semiconductor element. 2. The method according to claim 1, wherein the first step is
The vaporized substance collides in the space between the vaporizing device and the vaporizing device and the vaporizing device and the substrate or the semiconductor element arranged apart from the vaporizing device. And a step of growing the substance into the first particles by utilizing the bonding. 3. The method according to claim 2, wherein the third step is
The second step is performed by heating the substance to evaporate the substance, and then the third step is performed by reducing the heating temperature of the vaporizer and / or the pressure of the atmosphere. , Method of forming uneven film. 4. A substance having a light-transmitting property is grown on the first particles, and then the first particles are attached to one surface of a substrate having a light-transmitting property. A second particle made of the very small substance is attached to one surface of the substrate or the first particle attached to one surface of the substrate to form a translucent uneven film, A method of manufacturing a photoelectric conversion element, comprising forming a translucent conductive film, a photoelectric conversion film, and a conductive film on the formed uneven film in this order. 5. The method of manufacturing a photoelectric conversion element according to claim 4, wherein the light-transmitting substance is the same as the substance of the substrate. 6. A light-transmitting conductive material is grown on the first particles, the first particles are attached to one surface of the light-transmitting substrate, and then the first particles are formed. Second particles smaller in size than the conductive material are attached to one surface of the substrate or the first particles attached to one surface of the substrate to form a translucent conductive film having irregularities. A method for manufacturing a photoelectric conversion element, which comprises forming and forming a photoelectric conversion film and a conductive film on the translucent conductive film having the unevenness formed in this order. 7. A first substrate is provided on one surface of a transparent substrate.
Of the transparent conductive film and the photoelectric conversion film are sequentially stacked, the conductive material having a light-transmitting property is grown on the first particles, and then the first particles are attached onto the photoelectric conversion film. After that, the second particles having the unevenness are formed by attaching the second particles, which are smaller than the first particles and made of the conductive material, to the photoelectric conversion film or the first particles attached to the photoelectric conversion film.
A method for manufacturing a photoelectric conversion element, wherein the transparent conductive film is formed. 8. The photoelectric conversion according to claim 7, further comprising a reflective film formed on the second transparent conductive film, the reflective film reflecting light incident from the second transparent conductive film side. Device manufacturing method. 9. The average particle diameter according to claim 4, wherein the average diameter of the first particles is within a range in which incident light can be reflected in a direction different from the incident direction and can be attached. A method for manufacturing a photoelectric conversion element, in which the first particles are grown to have a size in a range. 10. The method for manufacturing a photoelectric conversion element according to claim 4, wherein the first particles are grown to have an average diameter of 0.05 μm to 1 μm. 11. The photoelectric conversion according to claim 4, wherein the first particles are attached so that the surface coverage of the first particles is in the range of 0.01 to 1. Device manufacturing method. 12. The method for manufacturing a photoelectric conversion element according to claim 4, wherein an uneven film made of a substance having a photocatalytic action is formed on the other surface of the substrate. 13. A transparent conductive film, a photoelectric conversion film, and a conductive film are sequentially laminated on one surface of a transparent substrate,
Manufacture of a photoelectric conversion element, in which a translucent conductive film, a photoelectric conversion film, and an uneven film made of a substance having a photocatalytic action are formed on the other surface of the substrate before, after, or during the formation of the conductive film. Method. 14. The uneven film formed of the substance having a photocatalytic action according to claim 12 or 13, after growing the substance having a photocatalytic action into third particles,
Particles are attached to the other surface of the translucent substrate, and then fourth particles of a substance having the photocatalytic action smaller than the third particles are attached to the other surface of the translucent substrate or the A method of manufacturing a photoelectric conversion element, which is formed by adhering to the third particles attached to the other surface. 15. The uneven film made of a substance having a photocatalytic action according to claim 12, wherein the film thickness difference between the concave portion and the convex portion of the uneven film is 0.2 μm or less. A method for manufacturing a photoelectric conversion element, which is formed in step 1. 16. A transparent substrate, a transparent conductive film formed on one surface of the transparent substrate, a photoelectric conversion film formed on the transparent conductive film, and the photoelectric conversion film. A photoelectric conversion device comprising: a conductive film formed on a conversion film; and a concavo-convex film formed on the other surface of the translucent substrate and made of a substance having a photocatalytic action.