JP3378774B2 - Film patterning method, method of manufacturing semiconductor device, thin film solar cell and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film patterning method that can be used when manufacturing a semiconductor element such as a thin film solar cell.

As a thin film type solar cell having a semiconductor film as a photoactive layer, a forward type and a reverse type are currently put into practical use. In the forward type, a transparent conductive film and an amorphous semiconductor film such as amorphous silicon including a pin junction and a back electrode film are laminated on a substrate having an insulating property and a light transmitting property such as a glass substrate. Having a large number of photoelectric conversion elements, electrically connecting the translucent conductive film of one photoelectric conversion element and the back electrode film of the other photoelectric conversion element between adjacent photoelectric conversion elements, In this configuration, a large number of photoelectric conversion elements are integrated in series. In each photoelectric conversion element, a substrate,
When light is sequentially incident through the translucent conductive film, a photoelectromotive force is generated in the amorphous semiconductor film, and the photoelectromotive force generated in each photoelectric conversion element is sequentially phased through the back electrode film. It is added and taken out.

On the other hand, the reverse type thin-film solar cell is a non-contact type which includes a back electrode film and a nip junction on a metal plate such as a stainless plate on which an insulating film is formed, or on a substrate having an insulating surface such as a plastic plate. A plurality of photoelectric conversion elements formed by laminating an amorphous semiconductor film such as crystalline silicon and a transparent conductive film, and a transparent conductive film of one photoelectric conversion element between adjacent photoelectric conversion elements and The back electrode film of the other photoelectric conversion element is electrically connected to form a configuration in which a large number of these photoelectric conversion elements are integrated in series. In each photoelectric conversion element, when light enters through the translucent conductive film, photovoltaic power is generated in the amorphous semiconductor film, and the photovoltaic power generated in each photoelectric conversion element passes through the back electrode film. Are added in series and taken out.

In both the forward type and the reverse type thin film solar cells, in order to form a large number of photoelectric conversion elements and integrate them, a light-transmitting film formed in the manufacturing process thereof is used. It is necessary to remove a predetermined region of the conductive conductive film, the amorphous semiconductor film, and the back electrode film and perform patterning. As a method of patterning such a thin film, a laser processing technique which is rich in fine workability and which irradiates a thin film with a laser beam as an energy beam to burn off a predetermined region is generally used.

[0005]

The film patterning method using the laser processing technique has the following problems. When the focus of the laser beam does not match the processing point due to the unevenness, scratches, warpage, etc. of the substrate, the processing remains. In addition, the scattered matter that is blown off by the irradiation of the laser beam adheres to another region again. Then, if there is such a processing residue or reattachment of scattered materials, current leakage through them or peeling of the amorphous semiconductor film and the back electrode film due to them may occur, resulting in a decrease in yield. There is. In addition, it is necessary to provide expensive laser beam irradiation equipment that is optimal for patterning each film,
There is also the problem of increased costs.

The present invention has been made in view of such circumstances, and by injecting a high-pressure liquid onto a region of a film to be removed, no unprocessed residue and re-adhesion occur, and a desired product can be easily and easily formed. An object of the present invention is to provide a film patterning method capable of patterning a film with a pattern.

Another object of the present invention is to provide a method of manufacturing a semiconductor device which can improve the yield by using such a film patterning method.

Still another object of the present invention is to provide a transparent conductive film,
By using such a film patterning method for patterning a photoelectric conversion film and a back electrode film, a thin film solar cell that can be manufactured with high yield at low cost, and separation between photoelectric conversion elements is accurately performed, and a manufacturing method thereof. To do.

[0009]

[Means for Solving the Problems]

The film patterning method according to claim 1 patterns the second film by removing a part of the second film made of a material different from that of the first film laminated on the first film. In the method described above, the pressurized liquid is sprayed onto the area of the second film to be removed so that the ratio of the etching rate of the second film to the etching rate of the first film is 10 or more. It is characterized in that the pH of the liquid is adjusted.

A method of manufacturing a semiconductor device according to claim 2 is
A method of manufacturing a semiconductor device having a patterned thin film, characterized by having a step of forming the patterned thin film using a film patterning method according to claim 1 Symbol placement.

A thin film solar cell according to a third aspect is a thin film solar cell in which a patterned transparent conductive film, a photoelectric conversion film and a back electrode film are laminated on an insulating transparent substrate. light conductive film, at least one layer of the photoelectric conversion layer and the back electrode film, characterized in that it is patterned using a film patterning method according to claim 1 Symbol placement.

According to a fourth aspect of the present invention, there is provided a thin film solar cell in which a patterned back electrode film is formed on a substrate having an insulating surface.
In the thin-film solar cell formed by stacking photoelectric conversion layer and the transparent conductive film, the back electrode layer, at least one layer of the photoelectric conversion film and the transparent conductive film, using the film patterning process according to claim 1 Symbol placement It is characterized by being patterned.

According to a fifth aspect of the present invention, there is provided a method for manufacturing a thin-film solar cell, which is a thin-film solar cell in which a patterned translucent conductive film, a photoelectric conversion film, and a back electrode film are laminated on an insulating translucent substrate. The method of manufacturing according to claim 1.
Using the film patterning process, the transparent conductive film, characterized by Patani <br/> ring at least one film of the photoelectric conversion film and the back electrode film.

According to a sixth aspect of the present invention, there is provided a method for producing a thin film solar cell in which a patterned back electrode film, a photoelectric conversion film and a transparent conductive film are laminated on a substrate having an insulating surface. A method according to claim 1 wherein the membrane is
A patterning method, the backside electrode layer, characterized in that it Patanin <br/> grayed at least one film of the photoelectric conversion film and the transparent conductive film.

An outline of the film patterning method of the present invention will be described. FIG. 1 is a schematic view showing an implementation state of the film patterning method of the present invention. In FIG. 1, reference numeral 3 denotes a laminated body formed by laminating the second film 2 on the first film 1,
The film 2 is patterned according to a predetermined pattern. The first film 1 and the second film 2 are films made of different materials. For example, the first film 1 is an amorphous silicon film and the second film 2 is a metal film. The high-pressure liquid 5 is jetted from above from the nozzle 4 to the laminated body 3 with a predetermined angle (θ) with the horizontal plane. At this time, the liquid 5 is ejected toward the removal target region of the second film 2. Then, the second film 2 is removed in the region where the liquid is ejected, and the desired patterning is realized.

The method of the present invention does not require a bulky device such as laser beam irradiation and does not require focusing.
The patterning of the second film 2 can be performed very easily and easily. Also, no heat is generated.

As the liquid to be used, a liquid that is easy to etch the second film 2 and difficult to etch the first film 1 is used. Specifically, a liquid having a ratio of the etching rate of the first film 1 to the etching rate of the second film 2 of 1:10 or more is used. In order to achieve such an etching rate ratio, the pH of the liquid used is adjusted to fall within the range of 2.5 to 6.0 or 8.0 to 11.5. In addition, the pressure of the liquid to be ejected is within the range of 100 to 500 kg / cm ² . Further, the injection angle θ is within the range of 30 to 90 degrees.
The reason for limiting these numerical values will be described later in the embodiment section.

According to the film patterning method of the present invention, there is no risk of re-deposition of scattered particles, which is left behind during patterning with a laser beam, and therefore semiconductor devices such as thin film solar cells having patterned thin films are manufactured. In many cases, the film patterning method of the present invention can contribute to the improvement of the yield. Taking a thin film solar cell as an example, by using the film patterning method of the present invention, a transparent conductive film,
The photoelectric conversion film and the back electrode film are reliably separated for each photoelectric conversion element, an electrical short circuit does not occur, and the yield is improved.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION A thin film solar cell will be described below as an example.
The present invention will be specifically described with reference to the drawings showing the embodiments.

(Embodiment 1) FIG. 2 is a schematic cross-sectional view showing a process of manufacturing a normal type amorphous silicon solar cell according to Embodiment 1. In the example of the first embodiment,
As will be described later, the patterned object is the back electrode film (Ag), and the jetting liquid is an alkaline solution.

First, the transparent conductive film 12 made of SnO ₂ is formed on the glass substrate 11 by the thermal CVD method to a thickness of several thousand Å.
After vapor deposition by (FIG. 2A), the translucent conductive film 12 is patterned by laser beam irradiation (FIG. 2).
(B)). Next, a single or a plurality of stacked bodies (thickness: a p-type amorphous silicon carbide layer, an i-type amorphous silicon layer, and an n-type amorphous silicon layer are stacked from the glass substrate 11 side by using a plasma CVD method) The amorphous semiconductor film 13 having a thickness of 2000 Å to 1 μm is formed (FIG. 2C). Specifically, diborane and methane are added to a silane gas atmosphere to form a p-type amorphous silicon carbide layer, an i-type amorphous silicon layer is formed only from silane gas, and phosphine is added to the silane gas to form an n-type An amorphous silicon layer is formed. The formed amorphous semiconductor film 13 is patterned by laser beam irradiation (FIG. 2D). Next, Ag
Then, the back electrode film 14 composed of is deposited to a thickness of 2000Å to 1 μm (FIG. 2E).

Then, the back electrode film 14 is patterned using the patterning method of the present invention (FIG. 2).
(F)). From a nozzle with a diameter of 0.01 mm, NaOH:
A liquid obtained by mixing 10 to 10 parts of water: 0.5 to 6
The back electrode film 14 is jetted to a desired region on the amorphous semiconductor film 13 to perform patterning. The distance between the tip of the nozzle and the portion to be processed is 5 mm, and the ejection angle of the liquid is perpendicular to the back electrode film 14. After that, pure water is flown around the patterning surface at a thickness of 1 to 3 mm and a flow rate of 2 to 5 m / sec to prevent the etching except the patterning region. Through the above processing, the back electrode film 14 of one photoelectric conversion element and the translucent conductive film 12 of the other photoelectric conversion element which are adjacent to each other are electrically connected, and integration of a large number of photoelectric conversion elements is realized. it can.

Hereinafter, various conditions of the patterning method of the present invention in such a normal type amorphous silicon solar cell will be considered.

Table 1 shows the results of examining the influence of the liquid on the jet pressure on the substrate. The effect on the base is to vertically spray a liquid mixed with NaOH: 10 at a ratio of water: 4 onto a predetermined portion of an amorphous silicon film having a thickness of about 2000 Å formed on a glass substrate. The surface roughness of the glass substrate surface with respect to the injection pressure at this time was measured. When the liquid injection pressure is up to 500 kg / cm ² , the surface roughness of the glass substrate does not change and 520 kg / c.
When it is more than m ² , the surface roughness increases and the influence on the base cannot be ignored. As described above, the threshold value of the injection pressure, which cannot be ignored in the influence on the base, depends on the film thickness and the type of the film to be patterned, the concentration of the liquid to be injected, and the like, and therefore the optimum injection pressure is set according to these. There is a need. Here, the following experiments were conducted with the injection pressure set to 500 kg / cm ² or less.

[0026]

[Table 1]

Next, the injection pressure was changed within the range of 500 kg / cm ² or less to inject a mixed solution of NaOH: 10 and water: 4, and the back electrode film was patterned to form a solar cell 10
0 sheets were manufactured and the yield was measured. The measurement results are shown in Table 2. The yield is the photoelectric conversion efficiency η is the maximum efficiency value η
Those that are 85% or more of the _max are calculated as non-defective products, and are shown as a relative value with the yield when they are formed by using the conventional laser beam irradiation. The film thicknesses of the amorphous semiconductor film 13 and the back electrode film 14 are 2000 Å and 400, respectively.
It is a constant value of 0Å.

[0028]

[Table 2]

Table 3 shows the patterning results when the pH of the jetted liquid was changed. In addition, Ag when changing the pH of the liquid (backside electrode film 14)
Table 4 shows the changes in the etching rate between the a-Si and the a-Si (amorphous semiconductor film 13). The thickness of each of the amorphous semiconductor film 13 and the back electrode film 14 was 4000 Å, and the liquid was a mixed solution of NaOH and water. As for the injection pressure, the result shown in Table 2 was the best, 400 kg / cm ²
And The method of obtaining the numerical value of the yield is the same as in Table 2.

[0030]

[Table 3]

[0031]

[Table 4]

From the results shown in Tables 2 and 3, a solar cell having a line width similar to that of conventional patterning by laser beam irradiation (line width of about 40 to 60 μm) was formed by jetting an alkaline solution having a limited pH. It can be seen that the yield can be improved by 10 to 40% as compared with the conventional manufacturing.

From the results shown in Table 3, the liquid pH was set to 7.
When the patterning was performed while changing it within the range of 9 to 12.5, the yield was improved as compared with the conventional example when the pH was 10.0 to 11.5, and the best yield was obtained when the pH was 11.5. I understand. In addition, as the liquid to be sprayed, pH =
When pure water of 7.0 was used, Ag and a-Si could not be selectively etched, and integration could not be performed, so that solar cell characteristics could not be obtained.

Further, from the results of Table 4, pH 7.9-1
When the etching rates of Ag and a-Si with respect to liquids within the range of 2.5 are compared, pH is 7.9 or less or 1
It can be seen that when the etching rate is 2.0 or more, the etching rate of Ag is less than 10 times the etching rate of a-Si. And
From the results of Tables 3 and 4, in order to equalize or improve the yield as compared with the conventional example (the yield of Table 3 is 1.0 or more, and the pH at that time is 8.0 to 11.5), a-Si
It can be seen that it is necessary to set the ratio of the etching rate of Ag to the etching rate of 10 to 10 or more.

Regarding the jetting angle of the liquid, patterning was carried out within a horizontal angle range of 30 to 90 degrees with respect to the processed surface, but no difference was found in the etching width, etching rate and yield.

In view of the above results, the first film (a-Si amorphous semiconductor film) having the etching rate of the second film (Ag back electrode film 14) to be patterned is the underlayer thereof. If a liquid having a pH in the range of 8.0 to 11.5, which is 10 times or more the etching rate with respect to 13), is used and the injection pressure is set to about 400 kg / cm ² , the efficiency of the second Film (Ag back electrode film 1
The patterning of 4) can be performed.

(Embodiment 2) FIG. 3 is a schematic sectional view showing a manufacturing process of an inverse type amorphous silicon solar cell in Embodiment 2. In the example of the second embodiment,
As will be described later, the patterned object is a translucent conductive film (ITO), and the ejection liquid is an acidic aqueous solution.

First, SiO _{2 is formed} on the SUS metal substrate 21.
After the insulating film 22 made of Ag and the back electrode film 23 made of Ag are vapor-deposited in this order with a thickness of several thousand liters (see FIG. 3).
(A)), the back electrode film 23 is patterned by laser beam irradiation (FIG. 3 (b)). Next, the back electrode film 23
The amorphous semiconductor film 24 (thickness 2000Å ~ 1) composed of a single or plural laminated body in which an n-type amorphous silicon layer, an i-type amorphous silicon layer and a p-type amorphous silicon layer are laminated from the side.
μm) is formed similarly to the first embodiment (FIG. 3).
(C)). After patterning the formed amorphous semiconductor film 24 by laser beam irradiation (FIG. 3D), ITO
A light-transmitting conductive film 25 made of is deposited with a thickness of several thousand liters (FIG. 3 (e)).

Then, the transparent conductive film 25 is selectively etched with respect to the amorphous semiconductor film 24 by using the patterning method of the present invention (FIG. 3F). 0.01m diameter
A liquid mixed with HNO ₃ : 1 to _{3 with} respect to HF: 1 is jetted from a nozzle of m to a desired region of the transparent conductive film 25 to perform patterning. The distance between the tip of the nozzle and the portion to be processed is 5 mm, and the liquid ejection angle is the translucent conductive film 2.
Vertical to 5. Then, pure water is flown around the patterning surface at a thickness of 1 to 3 mm and a flow rate of 2 to 5 m / sec to prevent etching of the area other than the patterning area.

Finally, the translucent conductive film 2 which has been etched
The amorphous semiconductor film 24 in the lower part of 5 is removed by laser beam irradiation (FIG. 3G). Through the above-described processing, the back electrode film 23 of one photoelectric conversion element and the translucent conductive film 25 of the other photoelectric conversion element which are adjacent to each other are electrically connected, and integration of a large number of photoelectric conversion elements is realized. it can.

Various conditions of the patterning method of the present invention in such an inverse type amorphous silicon solar cell will be considered below.

Table 5 shows the results of examination of the influence of the liquid on the jet pressure on the substrate. The measurement was performed on a SUS substrate with a SiO ₂ film of about 3000 Å and Ag of about 3000 Å.
And an amorphous silicon film having a film thickness of about 2000 Å are formed in this order, and KOH: 1, 1 is formed on a predetermined portion of the amorphous silicon film.
A liquid mixed with H ₂ O: 1 and propanol: 5 was vertically jetted, and the surface roughness of Ag at this time was measured. When the injection pressure of the liquid is up to 400 kg / cm ² , the surface roughness of the metal substrate does not change and
If it is more than kg / cm ² , the surface roughness increases and the effect on the base cannot be ignored. Therefore, the injection pressure is 400k
g / cm ² or less.

[0043]

[Table 5]

Table 6 shows the patterning results when the injection pressure was changed within the range of 400 kg / cm ² or less. The thickness of the amorphous semiconductor film 24 was fixed at 2000 Å, and the liquid used was a mixed liquid of HNO ₃ : 1 and H ₂ O: 1. The method of obtaining the numerical value of the yield is described in the first embodiment.
Is the same as.

[0045]

[Table 6]

Table 7 shows the patterning results when the pH of the jetted liquid was changed. Amorphous semiconductor film 2
The thickness of 4 is fixed at 2000Å and the liquid is mineral acid: 2,
A mixture of FeCl ₃ : 1 was used. The injection pressure is shown in Table 6
The result was 300 kg / cm ² , which was the best.
In addition, ITO when the pH of the liquid is changed
(Translucent conductive film 25) and a-Si (amorphous semiconductor film 2)
Table 8 shows the change in the etching rate with 4). The thickness of the transparent conductive film 25 is 1000 Å, the thickness of the amorphous semiconductor film 24 is 4000 Å, and the liquid is mineral acid: 2,
A mixture of FeCl ₃ : 1 was used.

[0047]

[Table 7]

[0048]

[Table 8]

From the results of Tables 6 and 7, the solar cells were formed by jetting an acidic solution having a limited pH with a line width comparable to that of conventional patterning by laser beam irradiation (line width of about 40 to 60 μm). Manufacture and yield 10 to 10
It can be seen that the improvement is 40%.

From the results shown in Table 7, the liquid pH was set to 2.
When the patterning is performed by changing it within the range of 0 to 6.1, the yield is improved compared with the conventional example when the pH is 2.5 to 5.0, and the highest yield is obtained when the pH is 3.0 and 3.5. It can be seen that the result is excellent and improved by 40%. If pure water with a pH of 7.0 is used as the liquid to be jetted,
Since the selective etching of O and a-Si could not be performed and the integration could not be performed, the solar cell characteristics could not be obtained.

Further, from the results of Table 8, pH 1.5-6.
When the etching rates of ITO and a-Si with respect to the liquid within the range of 1 are compared, the pH is 2.0 or less or 6.1.
The above shows that the etching rate of ITO is less than 10 times the etching rate of a-Si. Then, from the results of Tables 7 and 8, in order to make the yield equal to or higher than that of the conventional example (the yield of Table 7 is 1.0 or more, and the pH at that time is 2.5 to 6.0). Is the ratio of the etching rate of ITO to the etching rate of a-Si is 1
It can be seen that it needs to be 0 or more.

Regarding the liquid jet angle, patterning was performed within the range of 30 to 90 degrees horizontal to the processed surface, as in the first embodiment, but there was no difference in etching width, etching rate, and yield. I couldn't do it.

In view of the above results, the etching rate of the second film (transparent conductive film 25 of ITO) to be patterned is the first film (a-Si) which is the underlying layer.
Of an amorphous semiconductor film 24) having an etching rate of 10
When a liquid having a pH within the range of 2.5 to 6.0, which is more than double, is used and the injection pressure is set to about 300 kg / cm ^2, the second film (translucency of ITO is most efficiently transmitted). The conductive film 25) can be patterned.

In Embodiment 1 described above, the patterning method of the present invention was used only for patterning the back electrode film 14 (Ag), but the amorphous semiconductor film 13 (a) was used.
The patterning method of the present invention may also be used when patterning —Si) and the transparent conductive film 12 (SnO ₂ ). Similarly, in the second embodiment described above, the patterning method of the present invention is used only for selective etching of the transparent conductive film 25 (ITO) with respect to the amorphous semiconductor film 24 (a-Si). Amorphous semiconductor film 24 (a-Si)
Selective etching of the back electrode film 23 (Ag) of
The patterning method of the present invention may also be used when patterning the back electrode film 23 (Ag).

By the way, the patterning method of the present invention is
Other than the above examples, it can be applied to patterning various kinds of thin films. In Table 9 below, including the case of the embodiment described above, the jet liquid used when patterning one thin film of a laminate of two thin films made of different materials using the method of the present invention. For example: In Table 9, the thin film made of the substance shown on the left side is removed by etching and patterned. Even in this case, by using a liquid whose pH is adjusted so that the ratio of the etching rate of the second film to be patterned to the etching rate of the first film as the base is 10 or more, The influence of the film No. 1 on the film can be suppressed, and good patterning becomes possible.

[0056]

[Table 9]

[0057]

As described above, in the film patterning method of the present invention, the film is patterned by injecting a high-pressure liquid onto the region to be removed from the film. There is no re-attachment of scattered materials, and patterning can be performed accurately and easily.
In addition, when a semiconductor element is manufactured using such a patterning method, the yield can be improved. In particular, by adopting such a patterning method for patterning the translucent conductive film, the photoelectric conversion film, and the back electrode film of the thin film solar cell, the photoelectric conversion elements can be accurately separated, and the thin film solar cell can be manufactured with high yield. It can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a schematic view showing an implementation state of a film patterning method of the present invention.

FIG. 2 is a schematic cross-sectional view showing a manufacturing process of a normal type amorphous silicon solar cell.

FIG. 3 is a schematic cross-sectional view showing a manufacturing process of an inverse type amorphous silicon solar cell.

[Explanation of symbols]

1 first membrane 2 Second membrane 3 laminate 4 nozzles 5 liquid 11 glass substrate 12,25 Translucent conductive film 13, 24 Amorphous semiconductor film 14,23 Backside electrode film 21 SUS metal substrate 22 Insulating film

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-57-143477 (JP, A) JP-A-1-260830 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/306-21/308 C23F 1/00-3/06

Claims (6)

(57) [Claims] 1. The first film laminated on the first film
By removing a part of the second film made of a different material, the second film
In the method of patterning the film of
Injecting into the area of the second film to be removed,
The etching rate of the second film with respect to the etching rate of the first film
The p of the liquid is adjusted so that the ratio of the etching speed is 10 or more.
A film patterning method comprising adjusting H. 2. A semiconductor having a patterned thin film.
A method for manufacturing a device, wherein the film pattern is according to claim 1.
Forming the patterned thin film by using a thinning method
Of manufacturing a semiconductor device characterized by including a step of
Law. 3. A pattern is formed on a translucent substrate having an insulating property.
Translucent conductive film, photoelectric conversion film and back electrode film
A thin film solar cell in which the transparent conductive film,
At least one of the photoelectric conversion film and the back electrode film is a contractor.
Patterning using the film patterning method according to claim 1
Thin film solar cell characterized by being made. 4. A patternani on a substrate having an insulating surface.
The back electrode film, photoelectric conversion film, and translucent conductive film
In the laminated thin film solar cell, the back electrode film, the photoelectric
At least one film of the conversion film and the translucent conductive film is claimed.
Patterned using the film patterning method according to Item 1.
Thin film solar cell characterized by 5. A pattern is formed on a translucent substrate having an insulating property.
Translucent conductive film, photoelectric conversion film and back electrode film
Claim for a method of manufacturing a thin film solar cell in which
Item 2. The transparent conductive film is formed using the film patterning method according to Item 1.
At least one of an electric film, a photoelectric conversion film, and a back electrode film
Of thin film solar cells characterized by patterning
Build method. 6. A patternani on a substrate having an insulating surface.
The back electrode film, photoelectric conversion film, and translucent conductive film
A method for producing a laminated thin film solar cell, comprising:
The patterning method according to item 1 is used.
Back electrode film, photoelectric conversion film, and translucent conductive film
Patterning at least one film of
Method for manufacturing thin film solar cell.