WO2012105154A1

WO2012105154A1 - Method for manufacturing photoelectric conversion element

Info

Publication number: WO2012105154A1
Application number: PCT/JP2011/080458
Authority: WO
Inventors: 大介藤嶋
Original assignee: 三洋電機株式会社
Priority date: 2011-01-31
Filing date: 2011-12-28
Publication date: 2012-08-09

Abstract

A method for manufacturing a photoelectric conversion element (10) comprising: holding, on a transport tray (25), a layered structure (24) which includes a p-type amorphous silicon layer (12), an i-type a-amorphous silicon layer (13), an n-type single crystal silicon substrate (14), an i-type amorphous silicon layer (15), and an n-type amorphous silicon layer (16); forming a transparent electroconductive layer (17) on the surface of the layered structure (24) while held on the transport tray (25); and forming a metal layer (18) on the surface of the transparent electroconductive layer (17) while held on the transport tray (25).

Description

Method for manufacturing photoelectric conversion element

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

Patent Document 1 includes a first conductive type crystalline semiconductor substrate having a front surface and a back surface, and light is incident from the front surface side, an amorphous semiconductor film formed on the surface of the crystalline semiconductor substrate, A first transparent conductive film formed on the amorphous semiconductor film and containing a metal dopant of 1.5 mass% or more and 5 mass% or less, and a first transparent conductive film formed on the back surface of the crystalline semiconductor substrate A photovoltaic device comprising a second transparent conductive film containing a metal dopant less than the content of the metal dopant is disclosed.

JP 2004-221368 A

As the amount of water (hydrogen amount) contained in the transparent conductive layer increases, the sheet resistance of the transparent conductive layer can increase. For this reason, when the amount of moisture contained in the transparent conductive layer increases, it affects the current collection efficiency when the electricity generated by the photoelectric conversion unit of the photoelectric conversion element is collected by the collector electrode.

A method for manufacturing a photoelectric conversion element according to the present invention is formed on a first main surface of a crystalline semiconductor substrate including a first main surface and a second main surface opposite to the first main surface, and the crystalline semiconductor substrate. A laminated structure portion including the first semiconductor layer and the second semiconductor layer formed on the second main surface of the crystalline semiconductor substrate is held by the holding member, and the laminated structure portion is held by the holding member. A transparent conductive layer is formed on the surface of the transparent conductive layer, and a metal layer is formed on the surface of the transparent conductive layer while being held by the holding member.

According to the present invention, the characteristics of the photoelectric conversion element can be improved.

In embodiment which concerns on this invention, it is sectional drawing of a photoelectric conversion element. In embodiment concerning this invention, it is a flowchart which shows the procedure of the manufacturing method of a photoelectric conversion element. In embodiment which concerns on this invention, it is a figure which shows a conveyance tray. In embodiment which concerns on this invention, it is a schematic diagram which shows the manufacturing line of the process of S2. In embodiment which concerns on this invention, it is a flowchart which shows the procedure of the process of S2. In embodiment which concerns on this invention, it is a figure which shows a mode that a film | membrane accumulates on the surface of the tray main-body part of a conveyance tray by repeating the process of S2. In embodiment which concerns on this invention, for a comparison, it is a figure which shows a mode that a film | membrane accumulates on the surface of the tray main-body part of a conveyance tray by repeating the process of S2 without forming a metal layer. In embodiment which concerns on this invention, it is a schematic diagram which shows the manufacturing line of the modification of the process of S2. In embodiment which concerns on this invention, it is a flowchart which shows the procedure of the modification of the process of S2. In embodiment which concerns on this invention, it is a figure which shows a mode that a film | membrane accumulates on the surface of the tray main-body part of a conveyance tray by repeating the modification of the process of S2.

Embodiments according to the present invention will be described below in detail with reference to the drawings. In this description, specific shapes, materials, numerical values, directions, formation methods, manufacturing methods, and the like are exemplifications, and can be appropriately changed according to the application, purpose, specifications, and the like.

In the following, in all the drawings, the same symbols are attached to the same elements, and the duplicate description is omitted. In the description in the text, the symbols described before are used as necessary.

FIG. 1 is a cross-sectional view of the photoelectric conversion element 10. The photoelectric conversion element 10 is configured by laminating a transparent conductive layer 11, a laminated structure 24, a transparent conductive layer 17, and a metal layer 18 from the light receiving surface side. A collecting electrode 21 including a plurality of finger electrode portions (not shown) and a plurality of bus bar electrode portions 19 is provided on the light receiving surface of the photoelectric conversion element 10. In addition, a collector electrode 23 including a plurality of protruding electrode portions 22 is provided on the back surface of the photoelectric conversion element 10. Here, the “light receiving surface” means a surface on which light such as sunlight is mainly incident. The “back surface” means a surface opposite to the light receiving surface.

The laminated structure 24 includes, from the light receiving surface side, a p-type amorphous silicon layer 12, an i-type a amorphous silicon layer 13, an n-type single crystal silicon substrate 14, and an i-type amorphous silicon layer 15. The n-type amorphous silicon layer 16 is laminated.

The transparent conductive layer 11 is stacked on the p-type amorphous silicon layer 12. The transparent conductive layer 11 is made of, for example, a metal oxide such as indium oxide (In ₂ O ₃ ), zinc oxide (ZnO), tin oxide (SnO ₂ ), and titanium oxide (TiO ₂ ) having a polycrystalline structure. It is configured to include at least one. These metal oxides contain dopants such as tin (Sn), zinc (Zn), tungsten (W), antimony (Sb), titanium (Ti), aluminum (Al), cerium (Ce), and gallium (Ga). It may be doped. The concentration of the dopant can be 0 to 20 wt%. Here, the transparent conductive layer 11 is described as being formed using indium tin oxide (ITO). The film thickness of the transparent conductive layer 11 is preferably, for example, 100 nm in consideration of an anti-reflection (AR) effect.

The transparent conductive layer 17 is stacked on the n-type amorphous silicon layer 16. The transparent conductive layer 17 is made of, for example, a metal oxide such as indium oxide (In ₂ O ₃ ), zinc oxide (ZnO), tin oxide (SnO ₂ ), and titanium oxide (TiO ₂ ) having a polycrystalline structure. It is configured to include at least one. These metal oxides contain dopants such as tin (Sn), zinc (Zn), tungsten (W), antimony (Sb), titanium (Ti), aluminum (Al), cerium (Ce), and gallium (Ga). It may be doped. The concentration of the dopant can be 0 to 20 wt%. Here, the transparent conductive layer 17 is described as being formed using indium tin oxide (ITO). The film thickness of the transparent conductive layer 17 is preferably equal to or greater than the thickness of the transparent conductive layer 11, and is preferably, for example, from 100 nm to 150 nm.

The metal layer 18 is laminated on the transparent conductive layer 17. The metal layer 18 is laminated so as to cover substantially the entire surface of the transparent conductive layer 17 formation region. Here, “so as to cover substantially the entire surface of the region where the transparent conductive layer 17 is formed” means a state in which it can be considered that the transparent conductive layer 17 is substantially entirely covered. This includes a state in which a part of the metal layer 18 laminated is missing. The area of the formation region of the metal layer 18 is preferably in the range of 90% to 100% of the area of the formation region of the transparent conductive layer 17.

The metal layer 18 has a higher light reflectivity for light in the infrared region, particularly in the wavelength region of about 800 nm to 1200 nm, and higher conductivity than the transparent conductive layer 17 in the wavelength region used in the photoelectric conversion element 10. It is preferable to use a metal. For this reason, the metal layer 18 can be formed of a metal such as Ag, Al, Cu, Sn, Ni and Cr, or an alloy containing one or more of these metals. The metal layer 18 may be composed of a laminate of a plurality of films made of the above metals or alloys. As the metal layer 18, it is more preferable to use Ag having a high reflectance at wavelengths in the infrared region. The film thickness of the metal layer 18 is preferably, for example, 150 nm or more and 1000 nm or less, and more preferably 300 nm or more and 600 nm. Here, the metal layer 18 is described as being formed using Ag.

The metal layer 18 generally has higher light reflectance and conductivity than the transparent conductive layer 17. For this reason, when the metal layer 18 is formed on the back surface side of the photoelectric conversion element 10 via the transparent conductive layer 17, the light that has passed through the stacked structure portion 24 and reached the back surface is reflected by the metal layer 18, and again It can be led to the laminated structure 24. Thereby, the incident light and reflected light from the light-receiving surface side can be used effectively, and the conversion efficiency of the photoelectric conversion element 10 can be increased.

Since the metal layer 18 has a metal crystal structure, in general, the moisture permeability, moisture content, and moisture adsorption are smaller than those of the transparent conductive layer 17.
The transparent conductive layer 11, the transparent conductive layer 17, and the metal layer 18 may be formed not only by a sputtering method but also by a method such as vapor deposition or ion plating.

The bus bar electrode portion 19 is an electrode member provided for collecting and taking out the electricity generated in the photoelectric conversion element 10. It is preferable that the bus bar electrode portion 19 is arranged so as to collect the current collected as evenly as possible in the finger electrode portion arranged so as to collect current evenly from within the surface of the photoelectric conversion element 10. .

The protruding electrode part 22 is an electrode member provided for collecting and taking out the electricity generated in the photoelectric conversion element 10. The protruding electrode portion 22 is preferably disposed so as to collect electricity collected in the metal layer 18 as evenly as possible.

Each film thickness illustrated above can be measured using a transmission electron microscope (TEM). And each film thickness illustrated above has shown the average film thickness of the thickness along the lamination direction in the cross section of the photoelectric conversion element 10. FIG.

FIG. 2 is a flowchart showing the procedure of the method for manufacturing the photoelectric conversion element 10. Here, the procedure of the manufacturing method of the photoelectric conversion element 10 will be described. First, the laminated structure portion 24 is formed by the plasma CVD method (S1). Next, the transparent conductive layer 11 is laminated on the light receiving surface side surface of the laminated structure portion 24 by sputtering or vapor deposition with the laminated structure portion 24 held on the transport tray 25, and the back surface of the laminated structure portion 24. The transparent conductive layer 17 and the metal layer 18 are laminated on the surface on the side (S2). Finally, the collector electrode 21 and the collector electrode 23 are formed on the transparent conductive layer 11 and the metal layer 18 by screen printing, respectively (S3). In addition, you may perform the process of S2 and S3 with respect to the some laminated structure part 24 simultaneously.

Hereinafter, among the steps of the method for manufacturing the photoelectric conversion element 10, the step S2 will be described in detail.

FIG. 3 is a diagram showing the transport tray 25. The transport tray 25 is a holding member that holds the stacked structure portion 24. The transport tray 25 includes a tray main body portion 26 and a plurality of sub-trays 27. Here, as an example, a transport tray 25 that holds a plurality of stacked structure portions 24 is shown. The tray main body 26 is a plate-like support frame in which a rectangular opening is formed at the center. Each sub-tray 27 can be attached to and detached from the opening of the tray body 26, and has a structure in which a plurality of laminated structures 24 are sandwiched and held by plate-like members that can be divided vertically. The sub-tray 27 is configured to expose almost the entire front surface and back surface of the multilayer structure 24 while holding the plurality of multilayer structures 24 by sandwiching the end of the multilayer structure 24.

The sub-tray 27 has a size that can be fitted into the opening of the tray main body 26. A support member for supporting the sub-tray 27 is provided at the edge of the opening of the tray main body 26 along the juxtaposition direction of the sub-tray 27, and the sub-tray 27 fitted into the opening of the tray main-body 26 is not dropped by the support member. To be held.

Both ends of the sub-tray 27 are attached to the tray body 26 so as to be rotatable. Thereby, the front surface and the back surface of the laminated structure portion 24 held by the sub-tray 27 can be reversed with respect to the front and back surfaces of the tray main body portion 26.

FIG. 4 is a schematic diagram showing a production line in the step S2. FIG. 5 is a flowchart showing the step S2.

First, a plurality of laminated structures 24 on which the transparent conductive layer 11, the transparent conductive layer 17, and the metal layer 18 are to be formed are held by the sub-tray 27 (S10). Then, a predetermined number of sub-trays 27 are mounted on the tray body 26 (S12). As a result, a predetermined number of stacked structure portions 24 are held on the transport tray 25. Steps S10 and S12 are performed at the attachment / detachment position 40, which is a space region exposed to the atmosphere.

The transport tray 25 prepared in this manner is transported into the first vacuum device 42, and in the first vacuum device 42, a transparent conductive material is formed on the p-type amorphous silicon layer 12 of each stacked structure portion 24 by sputtering. Layer 11 is formed (S14).

Thereafter, the transport tray 25 is unloaded from the first vacuum device 42, and the sub-tray 27 mounted on the transport tray 25 is reversed. Thereby, the front surface and the back surface of the laminated structure 24 are reversed (S16). The process of S16 is performed at the reversal position 44, which is a space area exposed to the atmosphere. Then, the transport tray 25 is carried into the second vacuum device 46, and the transparent conductive layer 17 is formed on the n-type amorphous silicon layer 16 of the stacked structure portion 24 in the second vacuum device 46 by sputtering. (S18).

Next, the transport tray 25 is transported from the second vacuum device 46 into the third vacuum device 48, and the metal layer 18 is deposited on the transparent conductive layer 17 of the laminated structure portion 24 by sputtering in the third vacuum device 48. Form (S20). Thereafter, the transport tray 25 is unloaded from the third vacuum device 48 to the attachment / detachment position 40, and the sub-tray 27 is removed from the tray body 26 (S22).

When the steps S10 to S22 are completed, the sub-tray 27 holding the laminated structure 24 is removed from the tray body 26 and replaced with the sub-tray 27 holding the new laminated structure 24. When the steps S10 to S22 are repeated, as shown in FIG. 6, the surface of the tray main body 26 has a transparent conductive layer 11a, a transparent conductive layer 17a, a metal layer 18a, a transparent conductive layer 11a, and a transparent conductive layer 17a. , The metal layer 18a, the transparent conductive layer 11a,... Are repeatedly formed and deposited.

Generally, the transparent conductive layer 11a and the transparent conductive layer 17a have a polycrystalline structure including many crystal grain boundaries. In contrast, the metal layer 18a has a metal crystal structure with few crystal grain boundaries. Therefore, the metal layer 18a has less moisture and impurity adsorption at the crystal grain boundary and less moisture and impurity permeability through the grain boundary than the transparent conductive layer 11a and the transparent conductive layer 17a. Therefore, by forming the metal layer 18a on at least a part of the surface of the transport tray 25, moisture and impurities released from the transport tray 25 when the transport tray 25 is carried into the vacuum apparatus can be reduced. . Further, even if the transparent

conductive layers

11a and 17a are not yet deposited on the transport tray 25, the impurities and the like can be reduced by forming the metal layer 18a.

In the case where the transparent conductive layer 11a and the transparent conductive layer 17a are repeatedly formed without replacing the tray main body portion 26, if the metal layer 18a is not formed, the transparent conductive layer 11a is formed on the tray main body portion 26 as shown in FIG. The transparent conductive layer 17a, the transparent conductive layer 11a, the transparent conductive layer 17a, the transparent conductive layer 11a,... In such a state, when the formation process of the transparent

conductive layers

11 and 17 by the sputtering method is applied in the first vacuum device 42 or the second vacuum device 46, the transparent conductive layer 11a laminated on the tray main body 26, the transparent There is a possibility that moisture and impurities contained in the conductive layer 17a are released and simultaneously taken into the transparent

conductive layers

11 and 17 formed in the laminated structure portion 24 to adversely affect the film quality.

On the other hand, as shown in FIG. 6, a metal layer 18a is formed and covered on at least a part of the surface of the tray body 26, in particular, at least a part of the surface on which the transparent conductive layer 11a or the transparent conductive layer 17a is laminated. In this case, when the transparent

conductive layers

11 and 17 are newly formed using the tray body 26, the transparent conductive layer 11a and the transparent conductive layer 17a stacked on the surface of the tray body 26 by the metal layer 18 are included. The release of moisture and impurities can be suppressed. Therefore, the amount of moisture and impurities taken into the transparent

conductive layers

11 and 17 formed in the laminated structure 24 at the same time when forming the transparent

conductive layers

11 and 17 is reduced without replacing the tray main body portion 26. be able to. In general, since the sheet resistance increases as the amount of water in the films of the transparent

conductive layers

11 and 17 increases, an increase in the sheet resistance of the transparent

conductive layers

11 and 17 can be suppressed. Electric efficiency can be improved. In addition, since the transparent conductive layer 11 is formed in the next film formation process in which the metal layer 18 is formed, the transparent conductive layer 11 is compared with the transparent conductive layer 17 formed in the next film formation process in which the transparent conductive layer 11 is formed. The amount of water taken into the film can be further reduced.

Next, in the method for manufacturing the photoelectric conversion element 10, a modified example of the step S2 will be described. FIG. 8 is a schematic diagram showing a production line of a modification of the step S2. FIG. 9 is a flowchart showing a specific procedure of a modification of the step S2.

First, a plurality of laminated structures 24 on which the transparent conductive layer 11, the transparent conductive layer 17, and the metal layer 18 are to be formed are held by the sub-tray 27 (S30). Then, a predetermined number of sub-trays 27 are mounted on the tray body 26 (S32). As a result, a predetermined number of stacked structure portions 24 are held on the transport tray 25. Steps S30 and S32 are performed at the attachment / detachment position 50, which is a space region exposed to the atmosphere.

The transport tray 25 prepared in this way is transported into the first vacuum device 52, and in the first vacuum device 52, a transparent conductive material is formed on the n-type amorphous silicon layer 16 of each stacked structure portion 24 by sputtering. Layer 17 is formed (S34). Next, the transport tray 25 is transported from the first vacuum device 52 into the second vacuum device 53, and the metal layer 18 is deposited on the transparent conductive layer 17 of the stacked structure portion 24 by sputtering in the second vacuum device 53. Form (S36).

Thereafter, the transport tray 25 is unloaded from the second vacuum device 53, and the sub-tray 27 attached to the transport tray 25 is reversed. Thereby, the front surface and the back surface of the laminated structure 24 are reversed (S38). The process of S38 is performed at the reversal position 54, which is a space area exposed to the atmosphere. Then, the transport tray 25 is carried into the third vacuum device 56, and the transparent conductive layer 11 is formed on the p-type amorphous silicon layer 12 of the stacked structure portion 24 by the sputtering method in the third vacuum device 56. (S40).

Thereafter, the transport tray 25 is unloaded from the third vacuum device 56 to the attachment / detachment position 50, and the sub-tray 27 is removed from the tray body 26 (S42).

Subsequently, in the method for manufacturing the photoelectric conversion element 10, an operation of a modified example of the step S2 will be described. When the steps S30 to S42 are completed, the sub-tray 27 holding the stacked structure portion 24 is removed from the tray main body 26 and replaced with the sub-tray 27 holding a new stacked structure portion 24. When the processes of S30 to S32 are repeated, as shown in FIG. 10, on the surface of the tray body 26, the transparent conductive layer 17a, the metal layer 18a, the transparent conductive layer 11a, the transparent conductive layer 17a, the metal layer 18a, A film is repeatedly formed and deposited in the order of the transparent conductive layers 11a.

Therefore, even when the modified example of the step S2 is used, the metal layer is formed on at least a part of the surface of the tray main body 26, particularly at least a part of the surface on which the transparent conductive layer 11a or the transparent conductive layer 17a is laminated. 18a is formed and covered. Thus, when the transparent

conductive layers

11 and 17 are newly formed using the tray main body portion 26, the transparent conductive layer 11a and the transparent conductive layer 17a laminated on the surface of the tray main body portion 26 by the metal layer 18 are included. It is possible to suppress the release of moisture and impurities. Therefore, the amount of moisture and impurities taken into the transparent

conductive layers

11 and 17 increases, an increase in the sheet resistance of the transparent

conductive layers

Although the transparent

conductive layers

11 and 17 and the metal layer 18 have been described as being formed by different vacuum devices in the above-described step S2 and the modified example of the step S2, they may be formed by the same vacuum device. In the above-described step S2 and the modified example of the step S2, the inversion positions 44 and 54 have been described as being a space region exposed to the atmosphere, but may be a space region in a vacuum state.

As described above, in the photoelectric conversion element 10, the transparent conductive layer 11, the p-type amorphous silicon layer 12, the i-type amorphous silicon layer 13, the n-type single crystal silicon substrate 14, i from the light receiving surface side. Although described as a structure in which the type amorphous silicon layer 15, the n type amorphous silicon layer 16, the transparent conductive layer 17, and the metal layer 18 are stacked, the present invention is not limited to the stacked structure. For example, from the light receiving surface side, a transparent conductive layer, an n-type amorphous silicon layer, an i-type amorphous silicon layer, an n-type single crystal silicon substrate, an i-type amorphous silicon layer, a p-type amorphous silicon layer, A structure in which a transparent conductive layer and a metal layer are arranged side by side may be used.

10 photoelectric conversion element, 11, 11a, 17, 17a transparent conductive layer, 12 p-type amorphous silicon layer, 13 i-type amorphous silicon layer, 14 n-type single crystal silicon substrate, 15 i-type amorphous silicon layer, 16 n-type amorphous silicon Layer, 18, 18a metal layer, 19 bus bar electrode part, 21 collector electrode, 22 bus bar electrode part, 23 collector electrode, 24 laminated structure part, 25 transport tray, 26 tray body part, 27 sub-tray, 40 attachment / detachment position, 42 1st Vacuum device, 44 reverse position, 46 second vacuum device, 48 third vacuum device, 50 attachment / detachment position, 52 first vacuum device, 53 second vacuum device, 54 reverse position, 56 third vacuum device.

Claims

A crystal semiconductor substrate including a first main surface and a second main surface opposite to the first main surface; a first semiconductor layer formed on the first main surface of the crystal semiconductor substrate; and the crystal system Holding a laminated structure portion including a second semiconductor layer formed on the second main surface of the semiconductor substrate on a holding member;
In a state of being held by the holding member, a transparent conductive layer is formed on the surface of the laminated structure portion,
The manufacturing method of a photoelectric conversion element which forms a metal layer on the surface of the said transparent conductive layer in the state hold | maintained at the said holding member.
In the manufacturing method of the photoelectric conversion element of Claim 1,
The holding member is
A sub-tray for holding the laminated structure;
A tray body having an opening, and
Holding the laminated structure portion on the sub-tray;
A method for manufacturing a photoelectric conversion element, wherein the sub-tray is fitted into an opening of the tray main body.
In the manufacturing method of the photoelectric conversion element of Claim 2,
The sub-tray is
A plate-like first support frame;
A plate-like second support frame,
A method for manufacturing a photoelectric conversion element, wherein an end portion of the stacked structure portion is sandwiched between the first support frame and the second support frame.
In the manufacturing method of the photoelectric conversion element of Claim 2 or Claim 3,
The sub-tray is attached to the tray body so as to rotate with respect to the tray body.
Forming the transparent conductive film on the surface of the first semiconductor layer;
A method for manufacturing a photoelectric conversion element, comprising: forming the transparent conductive film on a surface of the second semiconductor layer after rotating the sub-tray.
In the manufacturing method of the photoelectric conversion element of any one of Claims 1-4,
The manufacturing method of the photoelectric conversion element which forms the said metal layer on a 50% or more area | region among the surfaces of the said transparent conductive layer.