JP3182323B2 - mask - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for forming a pattern.
More particularly, the present invention relates to a mask used in a method for forming a thin film pattern of a solar cell.

[0002]

2. Description of the Related Art Generally, a thin film is formed by a vapor deposition method, a sputtering method,
The thin film is formed by various forming methods such as a VD method.
Usually, in order to process into a desired shape, a pattern is formed by using a processing technique such as photoetching after forming a thin film.

[0003] One of applications using such a patterning technique is a thin-film solar cell. In order to form an integrated thin-film solar cell by series connection processing of thin-film solar cells, it is necessary to form relatively straight, parallel linear patterns at relatively simple intervals. That is, an integrated thin-film solar cell is formed by a series connection structure in which the metal thin-film back surface electrode of each photoelectric conversion element electrically contacts the end of the transparent conductive film electrode of the adjacent photoelectric conversion power generation element. In this integrated thin-film solar cell, a transparent conductive film electrode such as SnO ₂ or ITO is formed on a translucent insulating substrate such as glass, and an amorphous semiconductor photoelectric conversion layer and a metal thin film back electrode are formed thereon. Do it. Here, the amorphous semiconductor photoelectric conversion layer is formed by vapor phase growth such as a plasma CVD method or a photo CVD method by glow discharge decomposition of a source gas. The pattern formation of such an integrated thin-film solar cell is performed by forming each layer on the entire surface and then patterning each time. Means for patterning and integrating each layer include a photoetching method, a laser scribe method, and a method of patterning using a metal mask.

[0004] The photoetching method requires steps of mask alignment, application of a resist film, light irradiation, and cleaning, so that the number of steps is complicated, and the production cost increases as the thin film solar cell substrate becomes larger. . Further, during a chemical treatment step of immersion in a resist film removing liquid, the surface is damaged, which causes a reduction in the conversion efficiency of the solar cell.

The laser scribing method irradiates a laser beam while scanning a stage on which an object to be processed is placed,
Alternatively, it is possible to easily form a groove by scanning the object to be processed while irradiating the laser,
The production process is simplified, and production costs can be kept low. Further, since the groove width of the element division formed by laser scribing can be processed to 100 μm or less, the area of the electrode junction portion of the photoelectric conversion element can be small, the area not involved in photoelectric conversion is small, and the integrated thin-film solar cell The power generation effective area can be increased.

However, the laser scribing method requires extremely delicate processing technology and precision in patterning the reflective electrode on the back surface of the metal thin film, and has a problem that the yield in the production process is not high.

The patterning method using a metal mask is an effective method in terms of its simplicity, small number of steps, and cost.

[0008]

As described above, the patterning method using a metal mask is an effective means in terms of its simplicity, small number of steps, and cost. The metal mask rises from the substrate to be formed due to the influence, or the metal mask itself is deformed by thermal expansion of the metal, and the thin film material to be laminated wraps around and adheres to the portion covered with the mask, In some cases, the formed pattern is deformed and accurate patterning cannot be performed, which causes a reduction in yield. Usually, in order to prevent these, a method of fixing the metal mask using a magnet is used, but the metal mask may be further deformed by the influence of the magnetic force, and in this case, there is a problem that a fine pattern cannot be formed. Occurs.

Furthermore, in order to prevent the substance to be formed into a part covered with the mask from wrapping around and adhering, it is necessary to increase the adhesion strength between the metal mask and the substrate. Since it is necessary to increase the area of the metal mask crossbar to be fixed, the crossbar must be made thicker, and there is a problem that a fine pattern cannot be formed.

In addition, when a metal mask is applied to a solar cell substrate having a relatively large area, the metal mask to be used becomes large. In some cases, the battery substrate itself may be deformed. In this case, there is a problem that accurate patterning becomes more difficult.

[0011]

According to the present invention, there is provided a mask comprising a mask.
And a tension for applying tension to the cross in a predetermined direction.
Applying means, and a machine for supporting the crosspiece and the tension applying means.
Screen support and the mass to fix the position of the crosspiece
And a guide portion provided on the support member.
The cross-sectional shape must be a shape corresponding to the cross-sectional shape of the crosspiece.
And features.

Here, the cross-sectional shape of the guide portion is the cross-section of the crosspiece.
Since the shape corresponds to the shape, it is necessary to fix the crosspiece accurately.
Can be.

[0013]

[0014]

[0015]

Here, the tension applying means capable of giving a degree of freedom in a predetermined direction of the crosspiece is realized by applying a tension which can be extended and contracted in the length direction of the crosspiece by an elastic body such as a spring. . As a result, even if the pressing stress on the substrate is reduced due to the thermal expansion and contraction of the cross-section caused by the rise and fall of the temperature of the solar cell substrate due to the temperature at the time of forming the thin film, the tensioned state can always be maintained. For,
Adhesive stress to the substrate can always be maintained during film formation,
It is possible to prevent the substance to be formed into a part covered with the mask from coming around and adhering, thereby realizing patterning with high positional accuracy.

In particular, since the pattern of the integrated thin-film solar cell is a linear pattern, it is preferable to perform patterning using the mask of the present invention. According to the mask of the present invention, since the width of the masking bar is narrower than that of the conventional mask, the area of the electrode joining portion of each photoelectric conversion unit can be small, and the decrease in the effective area of the photoelectric conversion unit can be suppressed. Can be.

Further, as a material of the fine wire of the crosspiece as a mask, a thin metal wire such as a piano wire or a heat-resistant material fine wire such as a carbon fiber can be used. Triangular and rectangular shapes can be selected. That is, the cross-sectional shape is not limited to a circular shape, and a shape characterized by a portion partially including a linear portion can be used.

Since no magnet is required for fixing the mask, there is no influence of the distortion of the mask due to the magnetic force.

The mask according to the present invention includes a crosspiece as a mask,
Tension applying means for applying a tension to the bar in a predetermined direction;
A mask support for supporting the beam and the tension applying means;
The crosspiece and the tension applying means are integrally formed.
You.

Here, the crosspiece and the tension applying means are:
Since it is detachably provided on the mask support, it is easy to set and change the tension, and it is also easy to change the mask pattern by replacement and suitable for high-mix low-volume production.
Further, maintenance of the mask is facilitated.

[0022]

Here, the guide portion is realized, for example, by forming grooves on both ends of the mask support, so that the crosspiece can be accurately positioned, and the workability at the time of replacement is improved.

[0024]

FIG. 1 is a perspective view of a mask according to the present invention. The structure is such that a mask frame 1 which is a hollow mask support made of stainless steel is provided with a step 2 for dropping and fixing a substrate on which a pattern is to be formed, and one side of the mask frame 1 is provided with a bar 4 serving as a mask. Screw 3 for fixing
And a screw 3 for fixing the spring 5 so that tension is always applied even when the bar 4 is thermally expanded or contracted. The bar 4 and the spring 5 are integrally formed, and the bar 4 and the spring 5 are detachable from the screw 3 fixed to the mask frame 1. Therefore, the cross 4 and the spring 5
Of the screw 3 and the mask pattern can be easily changed.

A guide 8 is provided on the mask frame 1 by machine cutting in order to fix the bar 4. This is pier 4
However, it is intended to prevent lateral displacement due to the substrate's own weight, and to accurately determine the positioning of the rail 4.

In this mask, a stainless steel piano wire having a diameter of 100 μm is used for the bar 4, and a spring 5 is provided on an extension of the piano wire. Here, the bar 4 is made of a piano wire, but is not limited to this. For example, a heat-resistant material such as carbon fiber can be used, and in this case, the wire is more resistant to deformation than the piano wire.

FIG. 2 shows an example of the cross-sectional shape of the bar 4. The shape is not limited to a circle or a flat ellipse (FIGS. 2 (g) and 2 (h)), and a part of the cross-sectional shape may be a plane shape (FIGS. 2 (a) to 2 (f)). By adhering the plane-shaped portion of the cross-sectional shape to the film-forming surface, the contact between the crosspiece 4 and the film-forming surface is more reliably ensured, which is preferable.

FIG. 3 shows a sectional shape of the guide 8. The cross-sectional shape of the guide 8 is such that the shape of the bar 4 is fitted (FIG. 3A).
As shown in FIG. 2 (a) to (f), (f) corresponds to each of FIGS. 2 (a) to 2 (f), the cross-section of the V-shape, U-shape or the like allows the bar 4 to be more accurately fixed.

Next, how to use the mask will be described. At the time of pattern formation, the substrate on which pattern formation is to be performed is to be in close contact with the piano wire of the bar 4 with the film-forming surface facing down.
Drop it into the stage 2 and fix it, cover it with a holding plate 6 so as not to cause displacement due to vibration and the like, fix it with a fixed spring plate 7, and set it in a film forming device such as a plasma CVD device, a sputtering device, or a vapor deposition device. To form a film and form a pattern. Here, since the crosspiece 4 and the film-forming surface are in close contact with each other at the time of film-forming, the film-forming substance does not go around and adhere to the mask portion, so that accurate patterning can be performed.

Although a mask having a structure in which the crossbar 4 does not adhere to the film forming surface can be used, it is desirable to keep the mask closely, and the mask of the present invention is a material to be deposited from a certain direction such as sputtering or vapor deposition. It is good to use it for the process of flying.

FIG. 4 shows a case where the pattern forming method using the mask of the present invention is applied to an integrated thin-film solar cell.
It will be described based on.

First, a light-transmissive insulating substrate 41 having a thickness of 1 m
m glass substrate with a transparent conductive film electrode 4 on one side.
As No. ₂ , SnO ₂ is formed to a thickness of 1 μm by normal pressure CVD. Next, a laser beam is irradiated while scanning the paper in the vertical direction to perform patterning, and is separated into the respective transparent conductive film electrodes 42 (FIG. 4A). The laser beam applied at this time may be either a Nd: YAG laser or an excimer laser, but is easy to maintain and has a low running cost.
AG lasers have an industrial advantage.

Next, a p-layer of an amorphous semiconductor layer is laminated to a thickness of 12 nm. That is, the substrate is placed in a plasma CVD apparatus, and the temperature of the substrate is raised to 200 ° C. The reaction gas is monosilane gas at a flow rate of 30 sccm and methane gas at a flow rate of 89 scc.
m, the carrier gas is a hydrogen gas at a flow rate of 150 sccm, and the doping gas is a 1% hydrogen-diluted diborane gas at a flow rate of 10 sccm.
Flow in cm. Subsequently, an i-layer is laminated to a thickness of 400 nm. At this time, the substrate temperature is maintained at 200 ° C., the reaction gas is a monosilane gas at a flow rate of 60 sccm, and the carrier gas is a hydrogen gas at a flow rate of 20 sccm. Subsequently, an n-layer is laminated to a thickness of 100 nm. At this time, the substrate was kept at 200 ° C., the reaction gas was a monosilane gas at a flow rate of 60 sccm, the carrier gas was a hydrogen gas at a flow rate of 3 sccm, and the doping gas was 0.3 sccm.
% Hydrogen diluted phosphine gas at a flow rate of 18 sccm.
Thus, after the amorphous semiconductor photoelectric conversion layer 13 is laminated,
The scribe grooves are formed by irradiating the amorphous semiconductor photoelectric conversion layer 43 with laser light while scanning the paper perpendicularly to the paper surface.
(FIG. 4B).

Finally, using the mask shown in FIG.
Is set in a direction perpendicular to the plane of the paper, the translucent insulating substrate 41 is set as a mask, and ZnO of 50 is used as the transparent conductive film electrode 44.
Ag is laminated by sputtering or vapor deposition with a thickness of 500 nm, and then Ag is laminated with a thickness of 500 nm by sputtering or vapor deposition as the back surface reflective metal film 45. The film is separated into films 45 to form integrated thin-film solar cells (FIG. 4C).

The adjacent amorphous semiconductor photoelectric conversion layer 4
Although the p-layer and the n-layer of No. 3 are short-circuited by the transparent conductive film electrode 44, they are in a level that does not pose a practical problem due to serial operation, the degree of integration increases, and the groove between the amorphous semiconductor photoelectric conversion layers 43 is formed. This is the preferred shape when is narrow. However, the mask of the present invention can also be used when forming an integrated thin-film solar cell without filling the premises with the amorphous semiconductor photoelectric conversion layer 43.

In the above-described embodiment, the transparent conductive film electrode 44 and the back surface reflective metal film 45 are used for pattern formation, but may be used for pattern formation of other thin films.

[0037]

According to the present invention, an accurate patterning process can be performed even on a large-area substrate by applying a tension to each crosspiece of a mask in a predetermined direction, thereby eliminating the influence of a heat process during a film forming process. Since this method can be performed and the number of steps is small and the cost is superior, the present invention can be applied to a large-area integrated solar cell.

[Brief description of the drawings]

FIG. 1 is a perspective view of a mask according to the present invention.

FIG. 2 is a diagram showing a cross-sectional shape of a crosspiece.

FIG. 3 is a diagram showing a cross-sectional shape of a guide.

FIG. 4 is a view showing a cross section in each manufacturing process of the integrated thin film solar cell according to the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 mask frame 2 step 3 screw 4 beam 5 spring 6 holding plate 7 fixed spring plate 8 guide 41 translucent insulating substrate 42 transparent conductive film electrode (SnO ₂ ) 43 amorphous semiconductor photoelectric conversion layer (pin) 44 transparent conductive Film electrode (ZnO) 45 Back reflection metal film (Ag)

Continuation of the front page (56) References JP-A-63-283173 (JP, A) JP-A-1-225371 (JP, A) JP-A-4-116925 (JP, A) Japanese Utility Model Publication No. 64-44626 (JP) , U) (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 31/04-31/078 H01L 21/205

Claims (2)

(57) [Claims] 1. A bar as a mask, and the bar is mounted on the bar in a predetermined direction.
Tension applying means for applying tension, the crosspiece and the tension applying
Fix the position of the crossbar and the mask support that supports the means
And a guide portion provided on the mask support in order to
Provided, the cross-sectional shape of the guide portion, corresponding to the cross-sectional shape of the bar
A mask having a shape. 2. A bar as a mask, and the bar is mounted on the bar in a predetermined direction.
Tension applying means for applying tension, the crosspiece and the tension applying
And a mask support for supporting said means, and said crosspiece and said tension applying means are integrally formed.
And a mask characterized by the following.