JP2001250968A - Crystal silicon thin film semiconductor device, crystal silicon thin film photovoltaic element, and method of manufacturing for crystal silicon thin film semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crystal silicon thin film semiconductor device in which the crystallization rate of obtained polycrystalline silicon is high and which is superior in orientation property, a high characteristic and productivity, and to provide a crystal silicon thin film photovoltaic element and the manufacturing method of the crystal silicon thin film semiconductor device. SOLUTION: A transparent electrode 2 is installed on a glass substrate 1, and an Ni layer 4 as a metallic catalyst element is installed in an amorphous silicon layer on the transparent electrode 2. The, thermal treatment and crystallization are performed and a p-type polycrystalline silicon layer 5 is formed. The polycrystalline silicon layer 3 has orientation property and a high crystallization rate, and the p-type polycrystalline silicon layer 5 is formed with the polycrystalline silicon layer 3A as seed crystal. Thus, the polycrystalline silicon layer 5 has orientation property and the high crystallization rate. Then, an i-type polycrystalline silicon layer 6 and an n-type polycrystalline silicon layer 7 are sequentially formed on the polycrystalline silicon layer 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a crystalline silicon thin film semiconductor device, a crystalline silicon thin film photovoltaic element, and a method for manufacturing a crystalline silicon thin film semiconductor device. The present invention relates to a crystalline silicon thin film semiconductor device for producing a silicon thin film, a crystalline silicon thin film photovoltaic element, and a method for manufacturing a crystalline silicon thin film semiconductor device.

[0002]

2. Description of the Related Art In a semiconductor device such as a solar cell, in order to form a high-quality crystalline silicon-based device having a thickness of about 1 to 4 μm on a glass substrate having a conductive film, a glass substrate having a conductive film must be formed. It is necessary to directly form a high-quality seed crystal. Conditions necessary for forming the seed crystal include (1) high crystallinity (high crystallization rate), (2) orientation, and (3) a large amount of processing can be performed at one time. And (4) a low-temperature process in which a general glass substrate can be used.

Conventionally, a method of forming a polycrystalline silicon thin film on a heterogeneous substrate such as glass has been used for manufacturing a solar cell. According to this method, a large-area or high-quality silicon crystal substrate is not required, and significant cost reduction is expected. However, in order to manufacture a semiconductor device having good characteristics, it is necessary to improve the quality of a polycrystalline silicon thin film.
For this reason, quartz or the like that can withstand high temperatures is usually used for the substrate,
By performing a high-temperature deposition process on this substrate, a silicon thin film having good crystallinity is formed. However, in this method, cost is not reduced because expensive quartz or the like is used for the substrate.

[0004] In order to solve such a problem,
K. IEEE "First World" by Yamamoto and others
Conference on Photovoltaic Energy Conversion ”19
94 (pp. 1575-1578). In this method, amorphous thin-film silicon is melt-crystallized by a method such as laser annealing and is formed on the substrate surface to obtain polycrystalline thin-film silicon with good crystallinity. This makes it possible to use low-cost substrate materials. Attempts have also been made to directly form polycrystalline silicon on a glass substrate or the like having a conductive film by plasma CVD (Plasma Chemical Vapor Deposition).

As another method for solving the above problem, there is JP-A-9-82997. In this method, amorphous silicon is crystallized using a metal catalyst, and p or n is crystallized.
All of the crystal layers of the same conductivity type or BSF (Ba
A method of crystallizing all the p or n same-conductivity-type crystal layers including a ck surface field) layer is shown.

[0006]

However, according to the conventional crystalline silicon thin film semiconductor device and the conventional crystalline silicon thin film photovoltaic element, when amorphous silicon is crystallized on a glass substrate by laser annealing, a single process is performed. However, it is difficult to process a large number of substrates, and there is a problem in terms of throughput. That is, in order to form the amorphous thin film silicon into a polycrystalline layer having a uniform particle size by the melt crystallization method, the amorphous thin film silicon is formed by using the plasma CVD method, and then the amorphous thin film silicon is formed. Need to be thermally released, followed by laser annealing. For this reason, manufacturing takes time and effort, and the cost increases.

Further, the manufacturing method for directly forming polycrystalline silicon on a glass substrate or the like using plasma CVD has a problem in quality, such as a low crystallization rate of the obtained polycrystalline silicon. In a pn structure or a pin structure generally used in a solar cell, it is necessary to directly form a p-type or n-type polycrystalline silicon thin film on a glass substrate having a conductive film on the surface. It is known that a polycrystalline silicon thin film formed directly on a substrate has problems such as a low crystallization rate and a short carrier lifetime. In particular, a p-conductivity type polycrystalline silicon thin film obtained by plasma CVD has a very low crystallization rate and poor orientation, and is a major technical problem.

Further, according to the method disclosed in Japanese Patent Application Laid-Open No. 9-82997, Ni silicide (an alloy of Si and Ni) tends to remain at the junction with another conductive type, and the remaining Ni
Even when the silicide is removed by etching, defects are likely to occur, so that recombination at the junction increases, and the characteristics as a solar cell element may be significantly reduced.

Therefore, an object of the present invention is to provide a crystalline silicon thin film semiconductor device and a crystalline silicon thin film photovoltaic element which have a high crystallization rate, excellent orientation, high characteristics and high productivity of the obtained polycrystalline silicon. And a method of manufacturing a crystalline silicon thin film semiconductor device.

[0010]

According to the present invention, in order to achieve the above object, as a first feature, a conductive substrate or a substrate having a conductive layer formed on a surface thereof, the conductive substrate or the conductive substrate, A metal catalyst element is introduced in contact with the inside or surface layer of the amorphous silicon layer formed on the surface of the conductive layer, and the first layer having an orientation formed by crystallization of the amorphous silicon layer by heat treatment. A crystalline silicon thin film semiconductor device comprising: a polycrystalline silicon layer; and a second polycrystalline silicon layer formed using the first polycrystalline silicon layer as a seed crystal and having the same conductivity type as the first polycrystalline silicon layer. I will provide a.

According to this structure, the first polycrystalline silicon layer introduces a metal catalyst element into or in contact with the amorphous silicon layer formed on the substrate, and then performs a heat treatment. Thereby, it is converted into a polycrystalline silicon layer having orientation at a low temperature by the action of the metal catalyst element. This first
By forming the second polycrystalline silicon layer on the surface by using the silicon layer of the above as a seed crystal, the polycrystalline silicon having the same orientation as the underlying first polycrystalline silicon layer and having high crystallinity is obtained. A silicon layer is obtained. Further, the third polycrystalline silicon layer formed on the basis of the second polycrystalline silicon layer also has high crystallinity and orientation. As a result, the crystallization rate is high, the orientation is excellent,
A crystalline silicon thin film semiconductor device having high characteristics and high productivity can be obtained. In addition, since no silicide remains at the junction with another conductivity type, a removal step is not required, and no defect due to silicide occurs.

In order to achieve the above object, the present invention has, as a second feature, a conductive substrate or an insulating substrate having a conductive layer formed on a surface thereof; A metal catalyst element is introduced in contact with the inside or surface layer of the amorphous silicon layer formed on the surface, and the first conductive type is formed by crystallization of the amorphous silicon layer by heat treatment. A polycrystalline silicon layer, a second polycrystalline silicon layer formed by using the first polycrystalline silicon layer as a seed crystal and having the same conductivity type as the first conductivity type, and the second polycrystalline silicon layer A substantially i-type third polycrystalline silicon layer formed on the silicon layer; and a second conductive layer formed on the third polycrystalline silicon layer and having a conductivity type different from the first conductivity type. A fourth polycrystalline silicon layer having a mold; It provides a crystalline silicon thin film photovoltaic device characterized by having an electrode portion formed on the crystalline silicon layer.

According to a third aspect of the present invention, there is provided an insulating substrate having an electrode formed on a surface thereof, and a non-conductive substrate formed on the electrode of the insulating substrate. A first conductivity-type first polycrystalline silicon layer formed by crystallization of the amorphous silicon layer by heat treatment, wherein a metal catalyst element is introduced into the amorphous silicon layer or in contact with a surface layer portion of the amorphous silicon layer; A first conductive type second polycrystalline silicon layer formed by using the first polycrystalline silicon layer as a seed crystal; and a second conductive type second polycrystalline silicon layer formed on the second polycrystalline silicon layer. A polycrystalline silicon thin film photovoltaic device comprising: a third polycrystalline silicon layer; and an electrode portion formed on the third polycrystalline silicon layer.

According to the structure having the second and third features, the first polycrystalline silicon layer is formed in or on the amorphous silicon layer formed on the substrate and is in contact with the metal catalyst element. Is introduced, and then heat treatment is performed, whereby the polycrystalline silicon layer having orientation at low temperature is converted by the action of the metal catalyst element. By forming this first silicon layer as a seed crystal and forming a second polycrystalline silicon layer on the surface, it has the same orientation as the first polycrystalline silicon layer serving as a base and has high crystallinity. The resulting polycrystalline silicon layer is obtained. Furthermore, the third polycrystalline silicon layer formed on the basis of the second polycrystalline silicon layer has high crystallinity and orientation. Therefore,
A crystalline silicon thin-film photovoltaic device having a high crystallization rate, excellent orientation, high characteristics, and excellent productivity can be obtained.

According to a fourth aspect of the present invention, an amorphous silicon thin film is formed on the surface of a conductive substrate or on the surface of the conductive layer of a substrate having a conductive layer formed thereon. Then, a metal catalyst element is introduced in contact with the inside or the surface of the amorphous silicon layer, and a heat treatment is applied to the amorphous silicon layer to crystallize the amorphous silicon layer so that the amorphous silicon layer has an orientation. Forming a first polycrystalline silicon layer, and using the first polycrystalline silicon layer as a seed crystal to form a second polycrystalline silicon layer having the same conductivity type as that of the first polycrystalline silicon layer. Forming a third polycrystalline silicon layer having a second conductivity type different from that of the second polycrystalline silicon layer on the second polycrystalline silicon layer. Manufacture of crystalline silicon thin film semiconductor devices To provide a method.

According to this method, an amorphous silicon thin film is formed on the surface of the substrate, and a metal catalyst element is introduced into the amorphous silicon layer or in contact with the surface layer portion. By performing the heat treatment, the amorphous silicon layer can be crystallized at a low temperature, and a first polycrystalline silicon layer having orientation can be formed. By forming the first polycrystalline silicon layer as a seed crystal and forming a second polycrystalline silicon layer having the same conductivity type as that of the first polycrystalline silicon layer on the first polycrystalline silicon layer, The second polycrystalline silicon layer is converted into a polycrystalline silicon layer having the same orientation as the first polycrystalline silicon layer. Furthermore, a semiconductor device having a pn structure can be formed by forming a third polycrystalline silicon layer of a different conductivity type on the second polycrystalline silicon layer. Therefore, it is possible to manufacture a crystalline silicon thin film semiconductor device having a high crystallization rate, excellent orientation, high characteristics, and excellent productivity.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIGS. 1 and 2 show a first embodiment of a crystalline silicon thin film semiconductor device (crystalline silicon thin film photovoltaic element, ie, a pin type solar cell) according to the present invention. Here, FIG. 1 shows an intermediate step of the first embodiment of the present invention. FIG. 2 shows a completed state of the crystalline silicon thin film semiconductor device of FIG. This embodiment is an example of a semiconductor device in which a glass substrate is used and a transparent electrode mainly composed of tin oxide is formed on one side of the glass substrate, and a solar cell is formed on the transparent electrode.

As shown in FIG. 1, a transparent substrate 2 having a thickness of 800 nm was formed on a main surface of a glass substrate 1 as a substrate. The transparent electrode 2 was made of SnO _2, and was provided with irregularities on the surface (illustration of the irregularities was omitted in FIG. 1). H ₂ , SiH ₄ (silane), and B
_A gas mixture of ₂ H ₆ (diborane) was introduced and the pressure was 0.5
Torr, substrate temperature 420 ° C, frequency 6
An amorphous silicon layer 3 containing a p-type dopant was formed to a thickness of 20 nm by a 0 MHz p-CVD (plasma CVD) method. It is desirable that the thickness of the amorphous silicon layer 3 be 50 nm or less, and be as thin as possible. The reason is,
This is because the amorphous silicon layer 3 is used as a seed crystal when crystallizing with a metal catalyst element.

Next, a Ni layer 4 was formed to a thickness of 1 nm as a metal catalyst element by a vapor deposition method. Next, in a nitrogen atmosphere, a temperature of 450 to 700 ° C. (specifically, 500 to
(Temperature range of 600 ° C. to 600 ° C.) to diffuse the metal catalyst element (Ni). Note that this heat treatment is not limited to a nitrogen atmosphere, and a crystallization effect equivalent to that in a nitrogen atmosphere was obtained even when the heat treatment was performed in a vacuum atmosphere, a hydrogen atmosphere, an Ar atmosphere, or a halide atmosphere.

Further, the heat treatment was performed in two stages. First, the amorphous silicon layer 3 is heated at 400 ° C. in a hydrogen atmosphere to reduce the amount of hydrogen in the amorphous silicon layer 3 to 1% or less, preferably 0.3% or less.
% Or less. Then, when heated at 550 ° C., a p-type polycrystalline silicon layer 3A having a good orientation (shown in FIG. 2)
was gotten. The orientation of this polycrystalline silicon layer 3A is (1
10). In the above description, the amorphous silicon layer 3 is formed on the glass substrate 1 first, and then the metal catalyst element is introduced. However, first, the metal catalyst layer (Ni layer 4 ) May be directly deposited, and then the amorphous silicon layer 3 may be formed.

As the metal catalyst element, in addition to Ni, F
e, Co, Pt, Cu, Au and the like can be used.
When the metal catalyst layer is formed in a film shape, a plasma treatment method, an evaporation method, a spin coating method, or the like can be used. In the case of forming a line or an island,
For example, it can be formed by covering a portion that is not deposited with a metal mask by a deposition method. Further, as a method of introducing the compound into the film, for example, there are an ion implantation method, a plasma doping method, and the like. Further, since the metal catalyst layer is provided for a catalytic effect, its concentration may be extremely low. Normally, the thickness of a few layers is several angstroms, but even if it is a single metal layer, this proceeds along with the crystallization surface layer along with the reaction, and the entire surface is crystallized when it reaches the opposing surface. If so, it may be a single layer. When the quality of the seed crystal is not restricted, the crystallization may be performed under the condition that the catalyst metal remains in the film.

By the heat treatment as described above, the metal catalyst element diffuses in the amorphous silicon layer 3 and precipitates near the opposing surface between the amorphous silicon layer 3 and the transparent electrode layer 2 (that is, The metal catalyst element moves to the outermost surface of the p-type polycrystalline silicon layer 3A), and only a trace amount remains in the polycrystalline silicon layer 3A.
A was obtained. When the crystallinity is poor, Ni atoms are left behind in the film, but the thickness occupied by the seed crystal portion is 2% or less of the entire solar cell element, so that the performance as a solar cell element is greatly affected. Does not affect. Thus, the polycrystalline silicon layer 3A of the seed crystal containing Ni is
Even when the thickness is 5 nm or less, it can be formed without deteriorating the quality, and a high-quality element that does not substantially contain Ni that contributes to power generation can be produced. Furthermore, since there is no residual metal catalyst and no damage due to etching or the like at the junction where the crystal layers of different conductivity types that are important in the solar cell element are in contact, an ideal junction can be formed.

Next, a mixed gas of B ₂ H ₆ , H ₂ , and SiH ₄ was introduced, the pressure was maintained at 0.5 Torr, and p-CVD was performed at a substrate temperature of 200 ° C. and 60 MHz.
A conductive polycrystalline silicon layer 5 was formed to a thickness of 40 nm. Then, H ₂ and SiH ₄ were introduced, and the substrate temperature was set to 300.
An i-type polycrystalline silicon layer 6 was formed by a p-CVD method at 60 ° C. and 60 MHz. Although this thickness is necessary for light absorption, it is preferably at least 500 nm or more and about 10 μm, but can be used up to about 50 μm. At this time, 0.5% to 8% of hydrogen was contained in the film depending on the conditions. Since the polycrystalline silicon layer 5 is formed with the silicon layer 3A crystallized by the metal catalyst as a base, it follows the orientation of the silicon layer 3A (11).
0) It had an orientation and was much better in crystallinity than that formed directly on a glass substrate or the like, and was suitable for a solar cell element.

Further, with the i-type polycrystalline silicon layer 6 as a base, H ₂ , SiH ₄ and PH ₃ (phosphine)
Is introduced, the pressure is maintained at 0.3 Torr,
An n-type polycrystalline silicon layer 7 was formed to a thickness of 50 nm by p-CVD at a substrate temperature of 200 ° C. and 13.56 MHz. Although the optimum thickness of the polycrystalline silicon layer 7 varies depending on the crystallinity, it is 10 nm to 100 nm (preferably 30 nm).
nm to 60 nm). Finally, an Al film 8 was formed to a thickness of 1 μm by a vapor deposition method, and this was used as a back electrode. According to the above configuration, when the connection is performed in 50 stages by a known connection method of connecting the front side electrode and the back side electrode of the independent elements on the substrate in series, the characteristics obtained by adding the output voltages of the individual blocks are almost the same. Obtained.

In the above configuration, as the substrate material, for example, ceramics, quartz, sapphire, or the like can be used. Further, although an Al film was used for the back electrode, a metal such as Ag or Mo can be used in addition to the Al film.

In the first embodiment, a glass substrate is used and light is incident from the glass substrate side. However, a metal substrate is used instead of the glass substrate and light is incident from the thin film surface side. A configuration for performing this is also possible. This configuration example will be described below. (Second Embodiment) FIGS. 3 and 4 show a second embodiment (a pin type solar cell) of a crystalline silicon thin film semiconductor device according to the present invention. FIG. 3 shows a state up to an intermediate step.
FIG. 4 shows a completed state. The Si0 ₂ film 10 as an insulating film on a flexible SUS substrate 9 was formed to a thickness of 200 nm. Then, the SUS film 1 is formed on the surface of the SiO ₂ film 10.
1 was formed to a thickness of 500 nm, and this SUS film 11 was used as a back electrode. Next, an amorphous silicon layer 12 containing a 10 nm p-type dopant was formed on the SUS film 11 from a silicon target by a sputtering method. Si0 ₂ film 10
The amount of hydrogen in the inside was 0.1% or less. Further, a nickel salt solution was spin-coated on the surface of the amorphous silicon layer 12 and dried to form a Ni layer 13.

Next, 1 Torr of H_Two55 in the atmosphere
A heat treatment at 0 ° C. is performed for 30 minutes to form the amorphous silicon layer 12.
Crystallized to generate p-type polycrystalline silicon layer 12A
(FIG. 4). At this time, Ni in the Ni layer 13 is a SUS film.
Deposited near the interface between 11 and p-type polycrystalline silicon layer 12A
However, almost no residue remains in the p-type polycrystalline silicon layer 12A.
Was. Also, almost no p-type polycrystalline silicon layer 12A
Crystallization proceeded favorably because no hydrogen was present. this
B is formed on the p-type polycrystalline silicon layer 12A._TwoH₆, H _Two,
And SiH_FourAnd a pressure of 0.5 Torr.
Maintain force, substrate temperature 200 ° C, 60MHz p-CV
By the method D, the p-type polysilicon layer 14 is substantially formed.
Was formed to a thickness of 40 nm. Then H_TwoAnd SiH_Four
At a substrate temperature of 300 ° C. and 60 MHz.
Substantially i-type polycrystalline silicon layer by p-CVD
15 was formed to a thickness of 2 μm.

Further, a mixed gas of H ₂ , SiH ₄ , and PH ₃ is introduced, a pressure of 0.3 Torr is maintained, and an n-type polycrystal is formed by a p-CVD method at a substrate temperature of 300 ° C. and 13.56 MHz. The silicon layer 16 was formed to a thickness of 20 nm. Further, an ITO (indium tin oxide) film 17 as a transparent electrode was formed to a thickness of 70 nm, and a metal electrode 18 made of Al was formed partially to a thickness of 1 μm.
At this time, each of the obtained polycrystalline silicon layers 14, 15, 16 was oriented in the (110) plane. The polycrystalline silicon layer 16 can be oriented in the (111) plane according to the conditions of P-CVD. Polycrystalline silicon oriented to the (110) plane was characterized by a more natural texture than the (111) plane.

(First Comparative Example) When a thin-film polycrystalline silicon solar cell element is produced, as a method generally used conventionally, there is a method of forming all polycrystalline silicon layers by a p-CVD method. . With this method, a thin-film polycrystalline silicon solar cell having the same structure as that of the first embodiment of the present invention was prepared as follows, and compared with the present invention. The p-type polycrystalline silicon layer comprises H ₂ , SiH ₄ , and B ₂ H ₆
Was introduced by a p-CVD method at a pressure of 0.5 Torr, a substrate temperature of 200 ° C. and a frequency of 50 MHz. In addition, a mixed gas of H ₂ and SiH ₄ was introduced into the i-layer, and the i.
Maintain pressure at 5 Torr, substrate temperature 300 ° C, 60M
Hz p-CVD method, the n layer is H ₂ , SiH ₄ ,
And a gas mixture of PH ₃ were introduced, a pressure of 0.3 Torr was maintained, and a substrate temperature of 300 ° C. and a 13.56 MHz p.
-Prepared by the CVD method.

[0030] Thus, the fabricated current of the solar cell element - was subjected to a voltage measurement, the fill factor FF (curve fill factor is an index representing the performance of the solar cell: fill factor, FF = the maximum output P _max, the open-circuit voltage Assuming that V _OC and the short-circuit photocurrent density are J _SC , FF = P _max / (V _OC ×
J _SC )). That is, the fill factor FF of the polycrystalline silicon solar cell element according to the first embodiment was 1.47 times that of the polycrystalline silicon solar cell element of the first comparative example. The polycrystalline silicon solar cell element according to the first embodiment of the present invention uses a p-layer (polycrystalline silicon layer 12A) crystallized with a metal catalyst as a seed crystal, so that all elements can be formed by p-CVD. A solar cell element having better characteristics was obtained as compared with the solar cell element of the first comparative example in which the polycrystalline silicon layer was formed.

(Second Comparative Example) As in the first comparative example,
A second comparative example having the same structure as that of the second embodiment of the present invention was formed by p-CVD, and compared with the polycrystalline silicon solar cell element of the second embodiment. As a result, the fill factor FF of the polycrystalline silicon solar cell element according to the second embodiment of the present invention was 1.44 times that of the solar cell prepared in the second comparative example. In the second embodiment of the present invention, as in the first embodiment, the p-layer crystallized by the metal catalyst is used as a seed crystal, so that a solar cell element manufactured by a conventional method can be used. A solar cell element having good characteristics was obtained.

(Third Embodiment) Next, a third embodiment of the present invention will be described.
An embodiment will be described. In the first and second embodiments, the amorphous silicon layers 3 and 12 crystallized by introducing a metal catalyst have (110) orientation. On the other hand, in the third embodiment, an amorphous silicon layer containing a p-conductivity type dopant is formed to a thickness of 18 nm on the transparent electrode 2 in the first embodiment,
H ₂ , SiH ₄ and B _{2 are formed} on the amorphous silicon layer.
Introducing a mixed gas of H _6, VHF (very high frequenc
y) A polycrystalline silicon layer was formed to a thickness of about 2 nm by p-CVD with a frequency in the region under the condition of (111) orientation. Next, a nickel layer was formed to a thickness of about 2 nm on the (111) oriented polycrystalline silicon layer by a vapor deposition method, and then heat-treated at 500 ° C. for 1 hour. The polycrystalline silicon layer converted from the amorphous silicon layer by this heat treatment had a (111) orientation. Next, when a pin structure was formed in the same manner as in the first embodiment, all the silicon layers were oriented in the (111) plane. When the electrical characteristics of the solar cell device according to the third embodiment were measured, the fill factor FF was 0.9 compared to the solar cell device according to the first embodiment of the present invention.
It was eight times.

The above is an example of a solar cell element having a pin structure. However, since the characteristics of crystalline silicon obtained by the method of the present invention are good, a pn-type solar cell can be manufactured. This pn-type solar cell will be described below as a fourth embodiment. (Fourth Embodiment) FIG. 5 shows a fourth embodiment of the present invention. In the present embodiment, a pn-type solar cell as a crystalline silicon thin film photovoltaic element is formed on a glass substrate. An SiO ₂ film 19 serving as an insulating layer was formed to a thickness of 200 nm on a glass substrate 27, and a SUS film 20 was formed to a thickness of 500 nm as a back electrode. Next, amorphous silicon 21 containing an n-type dopant was formed to a thickness of 10 nm by sputtering. On top of this, a Ni catalyst layer (not shown) as shown in FIG. 2 or FIG.
Was formed to a thickness of 2 nm, and then a heat treatment at 500 ° C. was performed to convert the amorphous silicon layer 21 into a polycrystalline silicon layer 22A. Using this polycrystalline silicon layer 22A as a seed crystal, VHF p-CVD was performed to form an n-type polycrystalline silicon layer (not shown) with a thickness of 2 μm. The resistance of this n-type polycrystalline silicon layer is 20 to 100 Ωcm.
Met. Further, V is formed on the n-type polycrystalline silicon layer.
By performing HF p-CVD, the p-type polycrystalline silicon layer 23 is formed.
Was formed to a thickness of 500 nm. The resistance of this p-type polycrystalline silicon layer 23 was 0.1 to 30 Ωcm. Further, an IT as a transparent electrode is formed on the p-type polycrystalline silicon layer 23.
An O film 24 is formed to a thickness of 70 nm.
An Al electrode 25 was formed thereon, and a metal electrode 26 was partially formed on the Al electrode 25. Also in the solar cell manufactured in the fourth embodiment, when the back electrode and the front electrode were connected in series, a voltage obtained by adding the individual voltages was obtained even when the connection was performed in 50 stages.

FIG. 6 shows an embodiment of the fifth embodiment of the present invention.
You. In this embodiment, a silicon thin film light is formed on a glass substrate.
A PIN type solar cell is configured as an excitation power element.
is there. A transparent electrode 29 was formed on a glass substrate 28. Transparent
The electrode 29 has SnO_TwoWas used. Ni on the transparent electrode 29
Is formed, and then an amorphous silicon containing an n-type dopant is formed.
A 20 nm thick layer is formed, followed by a 550 ° C. nitrogen atmosphere.
Diffusion of the Ni metal catalyst layer to form an amorphous Si layer
Crystallization was performed. Then H2, SiH_Four, B_TwoH ₆Mixing
Gas is introduced and VHF (very high freq) is introduced.
ency) range by plasma-enhanced CVD.
A polycrystalline silicon layer 31 having a thickness of 40 nm was formed. This many
The crystalline silicon layer 31 was oriented in the (111) plane. Sa
H_Two, SiH_FourVHF plasma by introducing a mixed gas of
The i-type polycrystalline silicon layer 32 is 1 μm thick by CVD.
m and then PH_Three, H_Two, SiH_FourGas mixture
N-type polycrystalline silicon by VHF plasma CVD
A recon layer 33 was formed to a thickness of 50 nm. i-layer and n-layer
Therefore, it was possible to orient the crystal to the (110) plane. last
Then, an Al film 34 is formed to a thickness of 1 μm by a vapor deposition method,
The back electrode was used. The surface of this polycrystalline silicon thin film is
Structural structure suitable for photo-excited power device
It became. Furthermore, the underlying p-layer has a high crystallization rate.
To SnO_TwoWith p-layer formed directly by plasma CVD
Higher characteristics were obtained than the child.

Comparative Example A solar cell element having the same structure was formed only by plasma CVD, and the characteristics were compared with those of the above example. On the other hand, the solar cell device manufactured in the fifth embodiment had a fill factor FF of 1.51 times. By crystallizing using a metal catalyst, a solar cell element having better characteristics than a solar cell element manufactured by a conventional method was obtained.

When the crystalline silicon thin film semiconductor device and the crystalline silicon thin film photovoltaic element of the present invention described above are applied to a solar cell, they can be used for various types of devices such as a home power supply system and portable devices such as calculators and watches. Can be used for applications.

[0037]

As described above, according to the crystalline silicon thin film semiconductor device of the present invention, the metal catalyst element is introduced into or in contact with the amorphous silicon layer formed on the substrate. By performing the heat treatment, a first polycrystalline silicon layer obtained by being converted to a polycrystalline silicon layer having an orientation at a low temperature by the action of a metal catalyst element, and using the first silicon layer as a seed crystal, A second polycrystalline silicon layer provided in a structure having the same orientation with a high crystallization ratio; and a third polycrystalline silicon layer formed on the basis of the second polycrystalline silicon layer. With this configuration, it is possible to obtain a crystalline silicon thin film semiconductor device having a high crystallization rate, excellent orientation, high characteristics, and excellent productivity. In particular, a thin-film solar cell can be easily formed on an inexpensive substrate such as a glass substrate, and a low-cost, high-performance crystalline silicon thin-film semiconductor device can be obtained. Since silicide does not remain at the junction with another conductivity type, no defect due to silicide occurs.

Further, according to the crystalline silicon thin film photovoltaic device of the present invention, a metal catalyst element is introduced into or in contact with the amorphous silicon layer formed on the substrate, and then a heat treatment is performed. A first polycrystalline silicon layer converted into an oriented polycrystalline silicon layer by the action of a metal catalyst element, and a first polycrystal formed on the surface by using the first silicon layer as a seed crystal. A second polycrystalline silicon layer having the same orientation and high crystallinity as the silicon layer, and a third polycrystalline silicon layer formed on the second polycrystalline silicon layer so as to have high crystallinity and orientation. With the structure including the crystalline silicon layer, a crystalline silicon thin film photovoltaic device having a high crystallization rate, excellent orientation, high characteristics, and excellent productivity can be obtained.

Further, according to the method of manufacturing a crystalline silicon thin film semiconductor device of the present invention, an amorphous silicon thin film is formed on a surface of a substrate, and a metal catalyst element is formed in contact with the inside or surface layer of the amorphous silicon layer. And heat-treating the amorphous silicon layer to crystallize the amorphous silicon layer at a low temperature to form a first polycrystalline silicon layer having an orientation. The first polycrystalline silicon layer As a seed crystal, a second polycrystalline silicon layer having the same conductivity type and orientation as the first polycrystalline silicon layer is formed on the first polycrystalline silicon layer,
Since the third polycrystalline silicon layer of a different conductivity type is formed on the second polycrystalline silicon layer, the crystallization rate is high, and the orientation, the high characteristics, and the productivity are excellent. A crystalline silicon thin film semiconductor device can be manufactured.
In particular, when applied to a thin-film solar cell, an inexpensive substrate such as a glass substrate can be used, so that a high-performance semiconductor device can be obtained at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a solar cell according to a first embodiment of the present invention during manufacture.

FIG. 2 is a schematic sectional view showing a completed state of the solar cell of FIG.

FIG. 3 is a schematic cross-sectional view showing a solar cell according to a second embodiment of the present invention during manufacture.

FIG. 4 is a schematic sectional view showing a completed state of the solar cell of FIG.

FIG. 5 is a schematic cross-sectional view showing a solar cell according to a fourth embodiment of the present invention in the process of being manufactured.

FIG. 6 is a schematic cross-sectional view showing a fifth embodiment of the solar cell of the present invention.

[Explanation of symbols]

1,27 glass substrate 2 transparent electrode 3,12,21 amorphous silicon layer 3A, 5,12A, 14,22A, 23 p-type polycrystalline silicon layer 4,13 Ni layer 6,15 i-type polycrystalline silicon Layer 7, 16 n-type polycrystalline silicon layer 8, 25 Al film 9 SUS substrate 10, 19 SiO ₂ film 11, 20 SUS film 17, 24 ITO film 18, 26 Metal electrode

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yasushi Minagawa 3550 Kida Yomachi, Tsuchiura-shi, Ibaraki F-term in the Advanced Research Center, Hitachi Cable, Ltd. (reference) 5F045 AA08 AA19 AB03 AB04 AB32 AC01 AD06 AD07 AD08 AE19 AF07 AF09 AF10 BB12 CA13 DA52 DA59 DA61 HA16 HA20 5F051 AA03 AA16 CB12 CB24 CB29 DA03 DA04 GA02 GA03 GA06 5F052 AA11 CA04 CA10 DA02 DB03 DB07 EA13 EA15 FA06 HA06 JA09

Claims (16)

[Claims] 1. A conductive substrate or a substrate having a conductive layer formed on a surface thereof, and a metal in contact with an inside or a surface layer portion of the amorphous silicon layer formed on the conductive substrate or the surface of the conductive layer. A first polycrystalline silicon layer having an orientation formed by crystallization of the amorphous silicon layer by a heat treatment into which a catalytic element is introduced; and a first polycrystalline silicon layer formed by using the first polycrystalline silicon layer as a seed crystal. A crystalline silicon thin-film semiconductor device having a second polycrystalline silicon layer formed to have the same conductivity type as the polycrystalline silicon layer. 2. The method according to claim 1, wherein the second polycrystalline silicon layer has a thickness of 0.1.
2. The crystalline silicon thin-film semiconductor device according to claim 1, comprising at least hydrogen. 3. The crystalline silicon thin film semiconductor device according to claim 1, wherein said second polycrystalline silicon layer has an orientation in a film thickness direction. 4. The crystalline silicon thin film semiconductor device according to claim 1, wherein said second polycrystalline silicon layer has the same orientation as said first polycrystalline silicon layer. 5. The semiconductor device according to claim 1, wherein the second polycrystalline silicon layer has a second polycrystalline silicon layer on a surface opposite to the first polycrystalline silicon layer. 3. The crystalline silicon thin film semiconductor device according to claim 1, wherein a third polycrystalline silicon layer of the conductivity type is formed. 6. A third conductive layer having a different conductivity type from each of the second and third polycrystalline silicon layers, between the third polycrystalline silicon layer and the second polycrystalline silicon layer. 6. The crystalline silicon thin film semiconductor device according to claim 5, wherein a fourth polycrystalline silicon layer of conductivity type is formed. 7. The crystalline silicon thin film semiconductor device according to claim 5, wherein said third polycrystalline silicon layer has the same orientation as said second polycrystalline silicon layer. 8. The crystalline silicon semiconductor device according to claim 6, wherein said fourth polycrystalline silicon layer and said second polycrystalline silicon layer have the same orientation. 9. The crystalline silicon thin film semiconductor device according to claim 6, wherein said fourth polycrystalline silicon layer and said third polycrystalline silicon layer have the same orientation. 10. The crystalline silicon thin film semiconductor device according to claim 5, wherein said third and fourth polycrystalline silicon layers contain 0.1% or more of hydrogen. 11. A conductive substrate or an insulating substrate having a conductive layer formed on a surface thereof, and a conductive substrate or an amorphous silicon layer formed on a surface of the conductive layer inside or on a surface portion thereof. A first polycrystalline silicon layer having a first conductivity type formed by crystallization of the amorphous silicon layer by heat treatment, wherein the first polycrystalline silicon layer is formed by seeding the first polycrystalline silicon layer; A second polycrystalline silicon layer having the same conductivity type as the first conductivity type formed as a crystal, and substantially i formed on the second polycrystalline silicon layer
A third polycrystalline silicon layer of a type, a fourth polycrystalline silicon layer formed on the third polycrystalline silicon layer and having a second conductivity type different from the first conductivity type. A crystalline silicon thin-film photovoltaic device, comprising: an electrode portion formed on the fourth polycrystalline silicon layer. 12. The crystalline silicon thin-film photovoltaic device according to claim 11, wherein the conductive substrate is made of stainless steel, and the substrate on which the conductive layer is formed is made of glass. 13. A metal catalyst element is introduced in contact with an insulating substrate having an electrode formed on a surface thereof and an amorphous silicon layer formed on the electrode of the insulating substrate or in contact with a surface portion thereof. A first polycrystalline silicon layer having a first conductivity type formed by crystallization of the amorphous silicon layer by heat treatment; and a first polycrystalline silicon layer formed by using the first polycrystalline silicon layer as a seed crystal. A second polysilicon layer having the same conductivity type as the first conductivity type; and a second polysilicon layer formed on the second polysilicon layer and having a second conductivity type different from the first conductivity type. A polycrystalline silicon thin film photovoltaic device comprising: a third polycrystalline silicon layer; and an electrode portion formed on the third polycrystalline silicon layer. 14. An amorphous silicon thin film is formed on a surface of a conductive substrate or on a surface of the conductive layer of a substrate on which a conductive layer is formed, and is formed in contact with the inside or the surface of the amorphous silicon layer. Introducing a metal catalyst element, subjecting the amorphous silicon layer to a heat treatment to crystallize the amorphous silicon layer, thereby forming a first polycrystalline silicon layer having an orientation; Forming a second polycrystalline silicon layer having the same conductivity type as that of the first polycrystalline silicon layer on the first polycrystalline silicon layer using the polycrystalline silicon layer as a seed crystal; A method for manufacturing a crystalline silicon thin film semiconductor device, comprising forming a third polycrystalline silicon layer having a second conductivity type different from that of a crystalline silicon layer on the second polycrystalline silicon layer. 15. The method according to claim 14, wherein the amorphous silicon layer contains 0.3% or less of hydrogen. 16. The amorphous silicon layer has a thickness of 50.
The particle diameter is not more than nm.
The manufacturing method of the crystalline silicon thin film semiconductor device according to the above.