JP4156078B2 - Method for forming thin film solar cell pattern - Google Patents

Description

▲２▼（ａ−Ｓｉ：Ｈ（ｉ層）成膜条件）

▲３▼（Ｂ₂ Ｈ₆ ドープａ−Ｓｉ：Ｈ（ｐ層）成膜条件）

【００３８】
（４）＜エッチング処理＞
次に、アモルファスシリコン層下のＭｇＯ層パターン１３をエッチング液により除去した（図１（Ｆ））。これは前記のように水素で還元されたＭｇＯ層を酸で処理することにより除去することができる。
（エッチング条件）
エッチング液 ： ８０％酢酸溶液水溶液
エッチング時間： １０分
【００３９】
（５）＜透明電極パターンの形成＞
基材上全面にＩＴＯによる透明導電膜１５を反応性スパッタリング法により、全面に成膜した後、通常の方法でエッチングしてパターン形成した（図１（Ｇ））。
（スパッタ条件）

（パターニング）

【００４０】
成膜後は、透明導電膜１５がＭｇＯ層、アモルファスシリコン層が除去された部分にも堆積するため、透明導電膜と基材上のクロム電極とが接合して、セル間の直列接続がなされる（図１（Ｇ））。
【００４１】
（６）＜パッシベーション膜の形成＞
最後にパッシベーション膜１６を、ＣＶＤによる真空成膜法によりＳＮ_X 膜を形成して薄膜太陽電池を完成した（図１（Ｈ））。なお、成膜条件は次のとおりである。
（ＳＮ_X 膜成膜条件）

【００４２】
上記で作製された薄膜太陽電池にＡＭ−１（赤道上での太陽輻射スペクトルを再現した標準光源）を照射したところ、初期における太陽電池変換効率は８％程度であった。
【００４３】
【発明の効果】
本発明を薄膜太陽電池セルパターン形成に適用することで工程数が大幅に削減され、低コスト化に貢献できる。
【図面の簡単な説明】
【図１】 本発明による薄膜太陽電池セルパターンの形成法を説明する図である。
【図２】 アモルファスシリコン層を示す図である。
【図３】 第１の電極をパターン形成する際のマスクを示す図である。
【図４】 従来法による薄膜太陽電池セルパターン製造プロセスを示す図である。
【符号の説明】
１１ 基材
１２ 金属薄層またはクロム薄膜
１３ ＭｇＯ層パターン
１４ アモルファスシリコン層
１５ 透明導電膜
１６ パッシベーション膜
２１ 基材
２２ 金属電極層
２３ レジスト膜
２４ アモルファスシリコン層
２５ 透明導電膜
２６ パッシベーション膜[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a patterning process for a thin film solar cell. With the spread of solar cells, there is an increasing demand for cost reduction of solar cells. For this reason, reduction of the production cost of the cell patterning which is one of the thin film solar cell production processes is important. Thin film solar cell patterning methods include laser patterning, chemical etching, and the like, all of which have high production costs.
In contrast, according to the present invention, magnesium oxide is applied onto a metal electrode by a printing method, and an amorphous silicon (a-Si: H) layer is deposited thereon, so that the magnesium oxide is a-Si: H hydrogen. Since the pattern is formed using the characteristics that can be easily removed by being reduced, mask manufacturing and mask replacement work are not required, which is advantageous in reducing the production cost.
[0002]
[Prior art]
Conventionally, a silicon semiconductor has been the mainstream as a semiconductor material constituting a solar cell. However, since many silicon semiconductors in practical use are single crystals, it is difficult to increase the area. Moreover, since it is a single crystal, there are problems such as high cost, high manufacturing costs, and high power generation costs.
On the other hand, a thin film solar cell using amorphous silicon has been attracting attention as a solar cell that has a large absorption coefficient in the visible region and can reduce power generation costs. As the most practical configuration, for example, a first electrode is formed on a substrate, a photovoltaic generation layer is formed in the order of an n layer, an i layer, and a p layer, and then a second electrode is provided. Taken. As a substrate for these solar cells, a conductive metal material or an insulating substrate such as glass or plastic film can be used.
[0003]
FIG. 4 is a cross-sectional view showing a thin film solar cell manufacturing process according to a conventional method.
First, as shown in FIG. 4A, a base material 21 such as glass or a plastic film is prepared. Next, in order to form the first electrode on the base material, a metal thin film that becomes the metal electrode layer 22 is formed by vapor deposition, sputtering, or the like (FIG. 4B). The metal material may be any conductive material, and aluminum, copper, chromium, silver or the like is used. In order to form a metal thin film into an electrode pattern shape, a photosensitive resist material is applied on the metal thin film, and pre-baking, mask alignment, photomask exposure, and development processing are performed (FIG. 4C), and post-baking. Then, a resist film 23 is formed. Next, the metal thin film is etched through the resist film (FIG. 4D). Etching is usually chemical etching using ferric chloride or the like, but laser patterning can also be used. Thereafter, if the resist film 23 is peeled off, a metal electrode pattern is formed on the substrate (FIG. 4E).
Usually, a series of steps from application of the resist material to exposure, development, etching, and resist removal is referred to as “patterning”.
[0004]
Next, an amorphous silicon layer 24 is formed by laminating three layers in the order of n-type, i-type, and p-type on the metal electrode layer 22, and a photosensitive resist material is applied again to pattern the amorphous silicon layer ( FIG. 4 (F)). After forming the transparent conductive film 25 to be the upper electrode on the silicon layer, patterning is performed again to form a transparent electrode pattern (FIG. 4G). Finally, a passivation film 26 is formed to complete a thin film solar cell pattern (FIG. 4H).
[0005]
[Problems to be solved by the invention]
As described above, in the manufacturing method by chemical etching of a thin film solar cell according to the conventional method, it is necessary to repeatedly perform “patterning”, which increases the manufacturing cost of the solar cell. The same applies to laser patterning and the like.
Therefore, in the present invention, a method of partially providing a layer made of magnesium oxide or applying a magnesium hydroxide sol solution on a metal electrode by a printing method and then depositing an a-Si: H thin film is performed. Magnesium hydroxide is converted to magnesium oxide (MgO) by the firing step, and is reduced and weakened by hydrogen contained in a-Si: H, and can be easily peeled off with water, weak acid, or the like. By applying this to the pattern formation of solar cells, an a-Si: H layer pattern is formed at a high throughput to reduce the manufacturing cost.
[0006]
[Means for Solving the Problems]
The first of the gist of the present invention for solving the above-mentioned problems is that a metal electrode is formed in a pattern on a base material, and then a layer made of magnesium oxide is partially formed on the base material where the amorphous silicon layer is removed. After the formation, the amorphous silicon thin film is deposited on the entire surface including the magnesium oxide layer, and the amorphous silicon layer is patterned by removing the weakened magnesium oxide layer reduced by hydrogen contained in the amorphous silicon. A method of forming a thin-film solar battery cell pattern, comprising the step of: Since it is this formation method, a thin film photovoltaic cell pattern can be mass-produced at low cost.
[0007]
A second aspect of the present invention for solving the above problems is obtained by dispersing magnesium hydroxide fine particles bonded to a polyhydric alcohol or a derivative thereof in an organic solvent containing an organic compound having at least one hydroxyl group. A sol solution is applied onto a substrate on which a metal electrode pattern is formed and dried to partially form a layer made of magnesium oxide, and then an amorphous silicon thin film is deposited on the entire surface including the magnesium oxide layer to form amorphous silicon. A method for forming a thin-film solar cell pattern, comprising a step of patterning an amorphous silicon layer by removing a weakened magnesium oxide layer portion reduced by hydrogen contained in the substrate. Since it is this formation method, a thin film photovoltaic cell pattern can be mass-produced at low cost.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in more detail with reference to preferred embodiments.
When a fine-grained magnesium oxide (MgO) layer is formed as a base layer in a pattern forming portion and an a-Si: H layer is deposited on the portion, MgO is reduced by hydrogen in the a-Si: H layer. It can be easily peeled off by water or weak acid. As this MgO, commercially available magnesium oxide fine particles can be used.
If a commercially available product is highly cohesive and difficult to disperse in an organic solvent and a highly uniform coating layer cannot be obtained, prepare a magnesium hydroxide fine particle solution in a sol state, It is necessary to start from the step of applying the material onto the substrate by printing or the like. Hereinafter, the preparation of the magnesium hydroxide fine particle sol solution will be described first.
[0009]
<Preparation of magnesium hydroxide fine particle sol solution>
The sol solution is obtained by dispersing magnesium hydroxide fine particles (magnesium composite hydroxide fine particles) bonded to a polyhydric alcohol or a derivative thereof in an organic compound having at least one hydroxyl group or an organic solvent containing these. Sol solution. The magnesium composite hydroxide particles are produced by hydrolyzing a magnesium compound that becomes magnesium hydroxide in the presence of water into magnesium hydroxide with water and a polyhydric alcohol or derivative thereof using an appropriate catalyst. This is obtained by taking it out of its production medium.
[0010]
An example of preparation of magnesium composite hydroxide fine particles is shown below.
Table 1:Preparation example of magnesium composite hydroxide fine particles
50 parts by weight of pure water
150 parts by weight of ethylene glycol
Magnesium acetate (tetrahydrate) 21 parts by weight
Ammonia water (28% by volume) 6 parts by weight
Magnesium composite hydroxide is produced by stirring a mixed solution containing the composition shown in Table 1 above at room temperature for 1 hour. By separating this from the production medium by an appropriate method, granular fine particles of magnesium composite hydroxide are obtained.
[0011]
The above example is one example, and the magnesium compound generally used may be any magnesium compound as long as it produces a magnesium hydroxide in the presence of water. Further, about 50 to 950 parts by weight of polyhydric alcohol or a derivative thereof and about 25 to 1500 parts by weight of water are used per 100 parts by weight of the magnesium compound, and the magnesium compound is hydrolyzed with an appropriate catalyst. The catalyst may be any catalyst that promotes hydrolysis of the magnesium compound. For example, when the magnesium compound is a magnesium salt, a basic compound is used, and the equivalent amount or more with respect to 1 equivalent of the magnesium compound. Preferably, about 1 to 5 equivalents are used. When this catalyst is an aqueous solution such as aqueous ammonia as in the above example, the water in the aqueous ammonia solution can be used as the water in the above table.
[0012]
For the magnesium compound, instead of magnesium acetate in Table 1, for example, a strong acid magnesium salt represented by magnesium chloride, magnesium nitrate, and magnesium sulfate, or magnesium phosphate, magnesium hydrogen phosphate, magnesium dihydrogen phosphate, magnesium carbonate, citric acid, A weak acid magnesium salt represented by magnesium oxide, magnesium hydrogen citrate and magnesium formate, or an aliphatic carboxylic acid magnesium salt represented by magnesium stearate and magnesium myristate may be used.
[0013]
In Table 1, ethylene glycol that forms magnesium composite hydroxide fine particles and also serves as a solvent is a preferred example of a polyhydric alcohol or a derivative thereof. Instead of this ethylene glycol, for example, diethylene glycol, 2- Divalent alcohols and their derivatives represented by methoxyethanol, 2-ethoxyethanol and triethylene glycol, trihydric or higher polyhydric alcohols such as glycerin, mixed liquids thereof, and organics containing these A solvent may be used. Water as a solvent is an indispensable substance for producing fine particles of magnesium composite hydroxide, but it may not be necessary to add water on the assumption that water contained in ammonia water is used. Needless to say.
[0014]
In addition, ammonia in the ammonia water functions as a catalyst for promoting the production of magnesium hydroxide. Instead of this ammonia, ammonium acetate, ammonium amidosulfate, ammonium carbonate, ammonium bicarbonate, ammonium borate, dicitrate Various ammonium salts typified by ammonium, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium formate, and ammonium tartrate, or amines typified by hydroxylamine, ethanolamine, and methanolamine may be used.
[0015]
The method for separating the magnesium composite hydroxide from the mixed solution containing the magnesium composite hydroxide produced as described above is not particularly limited, and may be any method such as filtration, decantation, and centrifugation. A cooling centrifuge was used to separate the magnesium composite hydroxide fine particles produced in Table 1.
[0016]
The magnesium composite hydroxide fine particles obtained as described above are dispersed in an organic compound having at least one hydroxyl group or an organic solvent containing the same to obtain a sol solution used in the present invention. The amount of the organic solvent used with respect to the magnesium composite hydroxide can be arbitrarily set, but care must be taken because the coating film thickness is controlled by this parameter setting value. For example, considering the applicability of the resulting sol solution, the organic solvent as the dispersion medium is preferably used at a ratio of 100 to 500 parts by weight per 100 parts by weight of the magnesium composite hydroxide. When the solid content is too low, it is difficult to form a dense and continuous protective layer, and when the solid content is too high, the composite fine particles tend to aggregate and precipitate, and the uniformity of the formed coating layer tends to decrease. Therefore, it is not preferable. An example of the sol solution is shown in Table 2 below.
[0017]
Table 2:Example of preparation of sol solution
Magnesium composite hydroxide 5 parts by weight
10 parts by weight of ethanol
The dispersion method of the composite hydroxide may be a conventional dispersion means such as simple stirring, forced stirring, ball mill, sand mill, ultrasonic dispersion or the like, and a uniform sol solution can be easily obtained by these dispersion means.
[0018]
The ethanol as a dispersion medium of the sol solution is an example, and any compound having at least one hydroxyl group may be used. For example, instead of the above ethanol, monovalent alcohol represented by methanol, n-propyl alcohol, i-propyl alcohol, 1-butanol, 2-butanol, or ethylene glycol, diethylene glycol, 2-methoxyethanol, 2-ethoxy Dihydric alcohol represented by ethanol, triethylene glycol and derivatives thereof, trihydric or higher polyhydric alcohol represented by glycerin, and a mixed solvent thereof, or at least one of these hydroxyl group-containing organic solvents An organic solvent containing seeds may be used.
[0019]
The reason why the magnesium composite hydroxide fine particles are easily dispersed in the organic solvent by the simple dispersing means as described above is considered as follows. That is, since the preparation of the magnesium composite hydroxide fine particles is carried out in a polyhydric alcohol such as ethylene glycol or a derivative thereof, a polyhydric alcohol or a derivative thereof is added to each magnesium aco complex generated by hydrolysis, for example, Bonded or coordinated in a state such as hydrogen bond to form one kind of chelate complex, and as the complex concentration increases as the hydrolysis reaction proceeds by the catalyst, the chelate complexes associate with each other to form magnesium complex water. It becomes oxide fine particles. Since these fine particles (complex association) are not made from a magnesium-aco complex, but from a chelate complex made of a polyhydric alcohol or a derivative thereof, fine particle aggregates (aggregation of the complex) that tend to occur as the complex concentration increases. Less.
[0020]
Further, when the fine particles, which are aggregates of this chelate complex, are dispersed in a hydroxyl group-containing organic solvent, the hydroxyl group-containing organic solvent is adsorbed by the hydroxyl group, and the individual magnesium composite hydroxide fine particles are deposited on the fine particle surface. In other words, the presence of this protective film improves the affinity with the organic solvent, which is the liquid medium of the sol solution, and improves the affinity between the fine particles in the organic solvent. Aggregation is suppressed and the fine particles are considered to be easily and stably dispersed in the organic solvent. Considering only this effect, all organic compounds having a hydroxyl group have applicability. However, in order to produce a pure magnesium oxide film by removing the organic solvent in the drying process after applying the sol solution, it is relatively low. As the solvent for the boiling polyhydric alcohol or derivative thereof and the sol solution, it is preferable to use an organic solvent having a relatively low boiling point.
[0021]
In contrast to the above method, the surface of the magnesium oxide film formed from the sol solution prepared without using polyhydric alcohol or its derivative at the time of forming magnesium hydroxide was observed to have unevenness of about 200 nm size, and the surface roughness On the other hand, the surface of the magnesium oxide film prepared from the sol solution in which magnesium hydroxide is formed in the presence of polyhydric alcohol or its derivative as in this method has extremely small unevenness and is relatively flat. Yes. The reason for this phenomenon is considered as follows. That is, for example, ethylene glycol is a solvent having a boiling point of 196 ° C. Therefore, the aggregate after centrifugation of the magnesium hydroxide-ethylene glycol complex is in the form of a viscous cream. On the other hand, magnesium hydroxide formed without using a polyhydric alcohol or a derivative thereof is basically only an aggregate of magnesium hydroxide alone, and therefore the aggregate after centrifugation has little viscosity. That is, it is considered that the sol solution added with ethylene glycol exhibits the leveling effect of the fine particle aggregate after application of the sol solution, and the surface of the magnesium oxide after drying becomes flat. Further, the magnesium composite hydroxide fine particles in the sol solution of the present invention are a complex compared to the magnesium hydroxide fine particles prepared without using a polyhydric alcohol or a derivative thereof, so that the particles are less likely to be associated. Hard to do. Therefore, even if the concentration of the sol solution is relatively increased, the sol solution is stable, which is advantageous in processes such as storage stability, applicability, and drying.
[0022]
Further, as the solvent of the sol solution described above, instead of the alcohol organic solvent described above, use of water or a solvent having no hydroxyl group, for example, toluene, hexane, etc., the magnesium composite hydroxide fine particles are obtained. Since it becomes difficult to stably disperse in a solvent and aggregation precipitation is likely to occur, the use of an organic solvent having a hydroxyl group as described above or an organic solvent containing at least one of them as the solvent of the sol solution. preferable.
[0023]
<Pattern formation using magnesium hydroxide fine particle sol solution>
Next, a thin film solar cell formation method using the magnesium hydroxide sol solution will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a method for forming a thin-film solar cell pattern according to the present invention. First, as shown in FIG. 1A, a base material 11 such as glass or plastic is prepared, and a thin metal layer 12 to be a first electrode is formed on the entire surface of the base material by selective growth by a vapor deposition method, a CVD method. Alternatively, a thin film is formed by sputtering (FIG. 1B). Thereafter, a metal thin film pattern is formed by a normal photolithography technique (FIG. 1C). The electrode layer may be formed in a pattern by a mask deposition method.
[0024]
Next, the magnesium hydroxide fine particle sol solution is applied in a narrow groove shape across the substrate to the place where the amorphous silicon thin film is to be removed. The coating method can be a screen printing method or a letterpress printing method. When the wet coating film formed by coating is heated and dried, the magnesium hydroxide is oxidized to form an MgO layer pattern 13 composed of fine particles of magnesium oxide (FIG. 1D). The drying may be performed at a temperature and a time at which the organic solvent component in the wet film is substantially volatilized.
It is sufficient to carry out at a temperature of 350 ° C. or more for about 30 minutes to 3 hours.
Three layers (n-type layer, i-type layer, p-type layer) of amorphous silicon layers 14 are sequentially deposited on the substrate, that is, on the electrode metal thin layer 12 and the MgO layer pattern by the CVD method or the like (FIG. 1 ( E)). Since the three amorphous silicon layers only have to have substantially the same shape, the MgO layers may be the same. In FIG. 1E and thereafter, the amorphous silicon layer 14 is illustrated as a single layer, but in reality, the three layers are laminated.
[0025]
As a result, an a-Si: H layer thin film is deposited on the MgO layer pattern 13. When the a-Si: H layer is deposited on the MgO layer, the MgO layer is reduced by hydrogen contained in the silicon layer to become a fragile thin film. If this weakened portion is etched with a weak acid or the like, the MgO layer is peeled off from the first electrode or the substrate to obtain a patterned amorphous silicon layer (FIG. 1F).
Through the above-described steps, a thin film pattern that requires relatively little accuracy (for example, a line and space of 200 μm or less required for a solar cell) can be formed. It becomes possible to form without using.
[0026]
Various methods are known for the formation of an amorphous silicon layer, but the most frequently used method is silane gas (SiH_Four) Is introduced into a vacuum furnace, an electric field is applied, and plasma discharge is performed to form an amorphous silicon thin film on the substrate. At this time, when no impurity is added to the silane gas, the i-type layer is diborane (B₂H₆) As an impurity, the p-type layer becomes phosphine (PH_Three) Can be added to form an n-type layer. That is, the junction of the n · i · p layer can be formed by switching the gas. As described above, the n, i, and p types can be formed by one reaction layer only by switching the gas, but can also be continuously formed by a line that is performed in a reaction chamber in which each layer is separated. In this case, there is an effect that the residual impurities are less adversely affected.
[0027]
Subsequently, a second electrode pattern is formed by the transparent conductive film 15. For this purpose, a transparent conductive film is formed on the entire surface of the substrate, and then patterned by a normal method to form a second electrode pattern (FIG. 1G).
As a material used for the transparent conductive film, In₂O_Three, SnO₂, In₂O₂-SnO₂(ITO), TiO₂These can be formed by sputtering, electron beam evaporation, resistance heating evaporation, ion plating, or the like.
[0028]
Finally, a passivation film 16 is formed on the entire surface by a vacuum film formation method using CVD or the like, thereby completing a thin film solar battery cell pattern (FIG. 1 (H)).
As a passivation film material, Si_ThreeN_Four, SiO₂However, it may be a coating film of a polymer resin such as a transparent fluororesin paint or a fluoride polymer having excellent weather resistance.
[0029]
As the substrate 11 of the thin film solar cell, various materials can be used in addition to glass. For example, a resin film such as polyimide, polyester, polyethylene terephthalate, epoxy, polyacrylate, polyarylate may be used. Further, a conductive material can also be used as the first electrode. In this case, stainless steel, aluminum, copper, titanium, galvanized steel sheet, carbon sheet, etc. can be used.
[0030]
FIG. 1 (H) shows a thin film solar cell pattern obtained by the forming method of the present invention. The thin film solar cell according to the formation method of the present invention is not changed in structure or performance from that of the conventional pattern formation method by chemical etching. The one shown in the figure is a p-i-n type in which two unit cell patterns are connected in series and receive sunlight from the transparent conductive film 15 side, but a large voltage can be obtained by further joining the cell patterns. Obtainable. Although the current obtained by such a solar cell is a direct current, it can be converted by an inverter into a household AC power source.
[0031]
FIG. 2 is a diagram showing an amorphous silicon layer. This portion is a photovoltaic layer, and an n-type amorphous silicon layer 14n, an i-type amorphous silicon layer 14i, and a p-type amorphous silicon layer 14p are stacked from the substrate side. Sunlight passes through the transparent conductive film and photons are absorbed to form a pair of electrons and holes. However, since the electric field existing inside the silicon substrate moves electrons to n-type and holes to p-type, n Current flows from the mold to the p-type. This current is taken out and used.
[0032]
FIG. 3 is a diagram showing a mask used for pattern formation of the first electrode. The hatched portion 12m in FIG. 3 is masked, and the metal electrode layer remains on the white background portion. Further, the MgO layer pattern 13 is formed on the substrate corresponding to the position of the narrow dotted line width portion 13p in contact with or slightly overlapping the electrode pattern, and the a-Si: H layer on the MgO layer is removed, Since the transparent conductive film 15 is formed in the removed portion, a series connection structure of solar cells can be formed as shown in FIG.
Note that the photomask shape of the transparent electrode pattern is the same as that of the first electrode pattern, but the portion where the transparent electrode remains is shifted from the first electrode as shown in FIG.
[0033]
【Example】
Embodiments of the present invention will be described below with reference to FIGS.
(1) <Formation of first electrode pattern>
A clean transparent glass substrate (Corning “# 1737”) thickness: 1.1 mm, size 10 cm □ was prepared, introduced into a sputtering apparatus, and a metal thin film was formed on the entire surface using Cr as a target (FIG. 1). (B)) A chromium thin film 12 having an electrode pattern shape was formed by a normal photolithographic method (FIG. 1C). The photomask pattern shape shown in FIG. 3 was used. In FIG. 3, A = 40 mm and B = 10 mm. The film thickness of the chromium thin film 12 was 5000 mm.
[0034]
The conditions for chromium sputtering and patterning are as follows.
(Sputtering conditions)
Target: Cr (Purity: 99.99%)
Deposition temperature: 350 ° C
Sputtering pressure: 5 mTorr
DC power: 2.5kW
Ar flow rate: 100 sccm
Deposition rate: 20cm / sec
(Patterning)
Pattern formation method: photolithography method
Pattern shape: Line and space (line width 40 mm, space 10 mm)
[0035]
(2) <Formation of MgO layer>
Next, the sol solution prepared in Table 2 was printed on the narrow width portion where the a-Si: H layer on the substrate was removed by a letterpress printing method in which the sol solution was attached to the convex portions of the plate. After printing, drying was performed under conditions of a temperature of 350 ° C. and a time of 1.0 hour to form a 0.2 μm thick MgO layer pattern 13 made of magnesium oxide fine particles (FIG. 1D).
Plate shape: Line and space (convex part is line, line width is 1mm, space is 49mm)
[0036]
(3) <Amorphous silicon layer formation>
Subsequently, the base material was introduced into a vacuum reactor, and an amorphous silicon layer 14 was formed by a CVD method. In this process, three amorphous silicon layers 14 were sequentially deposited on the entire surface of the portion where the chromium thin film 12 was formed and the portion where the MgO layer pattern 13 was formed (FIG. 1E).
In this step, after (1) an n-type amorphous silicon layer [a-Si: H (n) layer] is first formed from the substrate side, (2) a non-doped i-type amorphous silicon layer [a-Si: H (i) layer] was formed, and finally, (3) a p-type amorphous silicon layer [a-Si: H (p) layer] was formed.
For the n-type of (1), an offline silicon wafer is crushed and 3% by weight of phosphorus (P) is used. For the p-type of (3), the silicon wafer is also crushed, What doped 10 weight% of boron (B) was used.
[0037]
Each film forming condition is as follows.
(1) (P-doped a-Si: H (n layer) film forming conditions)

(2) (a-Si: H (i layer) film forming conditions)

▲ 3 ▼ (B₂H₆Doped a-Si: H (p layer) film forming conditions)

[0038]
(4) <Etching treatment>
Next, the MgO layer pattern 13 under the amorphous silicon layer was removed with an etching solution (FIG. 1F). This can be removed by treating the MgO layer reduced with hydrogen with acid as described above.
(Etching conditions)
Etching solution: 80% acetic acid solution aqueous solution
Etching time: 10 minutes
[0039]
(5) <Formation of transparent electrode pattern>
A transparent conductive film 15 made of ITO was formed on the entire surface of the substrate by a reactive sputtering method, and then etched to form a pattern by a normal method (FIG. 1G).
(Sputtering conditions)

(Patterning)

[0040]
After the film formation, the transparent conductive film 15 is also deposited on the portion where the MgO layer and the amorphous silicon layer have been removed, so that the transparent conductive film and the chromium electrode on the base material are joined to form a series connection between the cells. (FIG. 1G).
[0041]
(6) <Formation of passivation film>
Finally, the passivation film 16 is SN by a vacuum film formation method using CVD._XA thin film solar cell was completed by forming a film (FIG. 1 (H)). The film forming conditions are as follows.
(SN_XFilm deposition conditions)

[0042]
When the thin film solar cell produced above was irradiated with AM-1 (a standard light source reproducing the solar radiation spectrum on the equator), the solar cell conversion efficiency in the initial stage was about 8%.
[0043]
【The invention's effect】
By applying the present invention to the formation of a thin-film solar battery cell pattern, the number of steps can be greatly reduced, which can contribute to cost reduction.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a method of forming a thin-film solar battery pattern according to the present invention.
FIG. 2 is a diagram showing an amorphous silicon layer.
FIG. 3 is a diagram showing a mask when patterning a first electrode.
FIG. 4 is a diagram showing a thin-film solar cell pattern manufacturing process according to a conventional method.
[Explanation of symbols]
11 Base material
12 Metal thin layer or chromium thin film
13 MgO layer pattern
14 Amorphous silicon layer
15 Transparent conductive film
16 Passivation film
21 Base material
22 Metal electrode layer
23 Resist film
24 Amorphous silicon layer
25 Transparent conductive film
26 Passivation film

Claims (2)

After forming a metal electrode in a pattern on the base material, after partially forming a layer made of magnesium oxide on the base material where the amorphous silicon layer is to be removed, the entire surface including the magnesium oxide layer A thin film solar cell pattern comprising a step of depositing an amorphous silicon thin film and patterning the amorphous silicon layer by removing a weakened magnesium oxide layer reduced by hydrogen contained in the amorphous silicon Forming method. A sol solution obtained by dispersing magnesium hydroxide fine particles bonded to a polyhydric alcohol or a derivative thereof in an organic solvent containing an organic compound having at least one hydroxyl group is formed on a substrate on which a metal electrode pattern is formed. After coating and drying to partially form a layer made of magnesium oxide, an amorphous silicon thin film is deposited on the entire surface including the magnesium oxide layer and reduced by hydrogen contained in the amorphous silicon to weaken the magnesium oxide layer. A method for forming a thin-film solar cell pattern, comprising the step of patterning an amorphous silicon layer by removing a portion.

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