JP2004068126A - Thin film forming equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a roll transport type thin film forming apparatus, and more particularly to a thin film forming apparatus for a thin film solar cell.
[0002]
[Prior art]
Thin-film solar cells are considered to be the mainstream of solar cells in the future because they are thin, lightweight, inexpensive to manufacture, and easy to increase in area.
[0003]
Conventional thin-film solar cells use a glass substrate, but research and development of a flexible solar cell using a plastic film and a metal film in light of weight, workability, and mass productivity have been promoted. Taking advantage of this flexibility, mass production has become possible by a roll-to-roll or stepping roll manufacturing method.
[0004]
In the above-described thin-film solar cell, a plurality of photoelectric conversion elements (or cells) are formed by stacking a metal electrode layer, a photoelectric conversion layer formed of a thin-film semiconductor layer, and a transparent electrode layer on a flexible electrically insulating film substrate. . By repeatedly electrically connecting a metal electrode of a certain photoelectric conversion element and a transparent electrode of an adjacent photoelectric conversion element, a voltage required for a metal electrode of the first photoelectric conversion element and a transparent electrode of the last photoelectric conversion element is obtained. Can be output. For example, in order to obtain an AC of 100 V as a commercial power source by converting into an AC by an inverter, the output voltage of the thin-film solar cell is desirably 100 V or more, and actually several tens or more elements are connected in series.
[0005]
Such a photoelectric conversion element and its serial connection are formed by forming an electrode layer and a photoelectric conversion layer, patterning each layer, and combining them. The configuration and the manufacturing method of the solar cell are described in, for example, JP-A-10-233517.
[0006]
FIG. 8 shows a conceptual diagram of the configuration of the thin-film solar cell described in the above-mentioned Japanese Patent Application Laid-Open No. 10-233517. FIG. 8 shows a perspective view of a flexible thin-film solar cell using a plastic film as a substrate. The unit photoelectric conversion element 62 formed on the front surface of the substrate 61 and the connection electrode layer 63 formed on the back surface of the substrate 61 are completely separated into a plurality of unit units, respectively, and are formed with their separation positions shifted. For this reason, the current generated in the photoelectric conversion layer 65, which is the amorphous semiconductor portion of the element 62, is first collected in the transparent electrode layer 66, and then through the current collecting hole 67 formed in the transparent electrode layer region, the current on the back surface is collected. Through the connection electrode layer 63, and further through the connection hole 68 for series connection formed outside the transparent electrode layer region of the device in the connection electrode layer region, outside the transparent electrode layer region of the device adjacent to the device. The extended lower electrode layer 64 is reached, and the two devices are connected in series.
[0007]
As described above, a method for manufacturing a thin film of the thin film solar cell includes a roll-to-roll method or a stepping roll method. Both types are provided with a substrate transfer means by a plurality of rolls, the former is a method of continuously forming a film on a substrate continuously moving in each film forming chamber, and the latter is simultaneously stopped in each film forming chamber. A method is used in which a film is formed on a substrate, and the substrate portion on which the film has been formed is sent to the next film forming chamber.
[0008]
The stepping roll type film forming apparatus is excellent in that the characteristics of each thin film can be obtained stably since gas mutual diffusion between the adjacent film forming chambers can be prevented. It is described in JP-A-6-292349 and JP-A-8-250431.
[0009]
FIG. 7 shows an example of a manufacturing process of a thin-film solar cell and an example of various devices in a roll-conveying-type manufacturing apparatus, which outline the method of manufacturing the thin-film solar cell described above. Each process is shown on the left side of FIG. 7, and the outline of the equipment used in each process is shown by arrows on the right side.
[0010]
The apparatus includes a punching apparatus 51, a sputtering apparatus 52 using a roll-to-roll method, a film forming apparatus 53 using a stepping roll method, a laser scriber 54, a characteristic evaluation apparatus 55, and the like. Each of the apparatuses includes unwinding rolls 1a and 1b. , 1c, 1d, 1e and winding rolls 2a, 2b, 2c, 2d, a guide roll 3, a tension roll 4, and the like.
[0011]
FIG. 6 shows an example of the detailed configuration of the sputtering apparatus using the roll-to-roll method as an example. In the apparatus shown in FIG. 6, the polymer resin film substrate 10 wound around the unwinding roll 11a is placed in an unwinding chamber 11 which is separated from the outside by a closed container and the inside of the container is evacuated by an exhaust pump 8. It is configured so that it is set, and the end portion of the film substrate 10 is wound around a winding roll 12 a in the winding chamber 12 via a plurality of guide rolls 5.
[0012]
The substrate 10 is transported by the rotation of the pay-out roll 6 and the press roll 7 in contact therewith, and while the substrate 10 is transported between the unwinding and winding rolls, the substrate 10 is kept in the preheating chamber 13 for releasing moisture in the substrate. The processing is performed via the respective processing chambers of the sputtering processing chambers 14 and 15. During this time, the substrate is heated by a total of six cast heaters 9 and one infrared heater 9a, each of which is installed in a closed vessel of each processing chamber. The distance between the heater 9 and the polymer resin substrate 10 is set to 10 mm or less, and is configured such that the substrate does not contact the heater. Reference numeral 13a denotes an image of a preliminary chamber for discharging the water released in the preliminary heating chamber 13 for releasing water and for reducing the pressure with the sputtering processing chamber, and includes the infrared heater 9a. Is provided.
[0013]
In the apparatus shown in FIG. 6, the substrate 10 is heated in a vacuum vessel by, for example, a casting heater 9 set at 350 ° C. Ar gas is used as the atmosphere gas, and the pressure in the vacuum vessel is controlled to be about 27 Pa (200 mTorr). During the heat treatment, a predetermined heating area tension ( _FP-P ) is applied to the film substrate in an area partitioned by the press rolls 7 on both sides. Further, a predetermined unwinding side and winding side tension (F _UW , F _W ) is applied between the unwinding and winding rolls (11a, 12a) located outside thereof and the press roll 7. .
[0014]
Next, the detailed configuration of each processing chamber will be described below with reference to FIG. FIG. 5 is an enlarged view of a portion corresponding to the sputter processing chambers 14 and 15 in FIG. In FIG. 5, unlike the apparatus shown in FIG. 6, a guide roll 5 provided at a substantially central portion between two casting heaters 9 in the substrate transfer direction in the processing chamber is provided at the center in the transfer direction of the substrate and at two right and left sides. And a total of three guide rolls (5a, 5b, 5c), and guide the substrate 10 between the center roll 5a and the two left and right rolls (5b, 5c). 14a and 15a indicate sputter targets. With the three guide rolls, a constant tension can be applied to the film substrate without slackening.
[0015]
[Problems to be solved by the invention]
By the way, the conventional thin-film solar cell manufacturing apparatus has the following problems.
[0016]
When a thin film such as a metal electrode film is formed on a flexible film substrate by a conventional manufacturing apparatus, the effect of heat applied to the substrate by a heater or sputter discharge (or CVD) and the processing (or transporting) However, there is a problem that wrinkles parallel to the transport direction are generated on the film substrate due to the influence of the tension applied to the substrate.
[0017]
The above cases of wrinkles are roughly classified into two cases. One is a case where the film substrate is rapidly heated and shrunk, and the other is a case where the heated substrate is rapidly cooled and wrinkles are generated. That is, wrinkles are more likely to occur as the temperature difference between the rise and fall of the substrate temperature is larger. In either case, if the film substrate is wound up while wrinkles are generated, its shape remains as it is until the next step.
[0018]
In addition, the optimal temperature of the substrate is determined according to the processing characteristics of the substrate, and the speed at which the temperature rises to the ultimate temperature is determined in consideration of the above.In the manufacturing process, when the temperature of the substrate is repeatedly raised and lowered, Wrinkles may occur.
[0019]
When a thin film or the like is formed on a wrinkled substrate, uniformity of the film cannot be obtained, which causes deterioration in characteristics of the thin film solar cell and poor appearance. If wrinkles are present, extra stress remains in the thin film after formation, so that a problem such as peeling of the formed thin film occurs over time.
[0020]
The wrinkles generated as described above cannot be sufficiently prevented by the configuration of the three guide rolls as shown in FIG. 5, and in order to suppress the generation of wrinkles, the applicant of the present application first described Japanese Patent Application No. 2002-59045 has filed an application for an invention of a manufacturing apparatus for a thin film solar cell as described below.
[0021]
That is, "a substrate temperature for reducing a temperature difference between a rise and a fall of a film substrate heated in an upstream processing step, at least in part in a roll transport processing step between a film substrate unwinding chamber and a winding chamber. For example, a casting heater for heating a substrate is divided into two parts to provide a casting heater for high temperature and a casting heater for low temperature, and the temperature is increased in the first half of each heater and decreased in the latter half to reduce the substrate temperature. By suppressing the generation of wrinkles "(see Japanese Patent Application No. 2002-59045 for details).
[0022]
According to the invention of Japanese Patent Application No. 2002-59045, wrinkles due to thermal effects can be reduced, but the device configuration and heater operation become complicated. Further, since the substrate temperature difference reducing means and the sputter processing device are sequentially provided, there is a disadvantage that the size of the device is increased. Furthermore, the problem of wrinkles occurring and remaining due to residual stress remains.
[0023]
However, when priority is given to simply eliminating wrinkles, a method of winding a film substrate around a large drum roll, a so-called can roll method, is effective. In this case, the diameter of the drum roll must be increased as the film forming area increases. Therefore, there is a problem that the entire apparatus including the drum roll becomes large.
[0024]
As a different method for eliminating wrinkles, it is conceivable to increase the number of guide rolls. As shown in FIG. 5, one of the methods is to provide a plurality of sets of three guide rolls in the process direction, that is, the flow direction of the substrate. In this case, as described above, The device becomes longer in the horizontal or vertical direction, resulting in a larger overall device.
[0025]
Further, a method of arranging a large number of guide rolls in an arc shape has also been proposed. In this method, the outer periphery of a large-diameter drum roll in the can roll method is apparently divided by a plurality of guide rolls and arranged in an arc shape, thereby providing a function similar to the can roll method. It is. This method is considered to be the proposed method because there is a limit in increasing the diameter of the drum roll in the can roll method, but the problem that the entire apparatus becomes large is the same as the can roll method.
[0026]
The present invention has been made in order to solve the above problems, and an object of the present invention is to suppress the problem that wrinkles occur on a film substrate during a manufacturing process, thereby improving manufacturing yield and quality stability. It is another object of the present invention to provide a thin film forming apparatus, and in particular, a manufacturing apparatus for a thin film solar cell, in which the size of the thin film solar cell is reduced.
[0027]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a film substrate unwinding roll and a winding roll, and is disposed between the two rolls to guide the transport of the substrate and apply a predetermined tension to the substrate. A substrate transporting means having a plurality of guide rolls, and a thin film forming apparatus of a roll transport type comprising a thin film forming processing chamber for forming a predetermined thin film on the substrate,
The plurality of guide rolls are arranged on a line (A, B line) having a predetermined interval (d) and parallel to each other with the center of the roll axis of each of the plurality of guide rolls, and on the A, B line. Are arranged so that the center of the roll axis is different from each other,
Further, the substrate is transported alternately between the guide rolls on the A and B lines in a staggered manner, and a predetermined tension is applied to the substrate extending between two guide rolls on the adjacent A and B lines. (D), the predetermined interval (d) is determined so as to be added.
[0028]
According to the above configuration, there is an advantage that a predetermined tension can be easily applied to the film substrate at predetermined intervals, the tension control mechanism is simple, and a relatively large space is not required. Therefore, with a relatively small device, the problem of wrinkles occurring on the film substrate during the manufacturing process can be suppressed.
[0029]
As an embodiment of the first aspect of the invention, the following second to sixth aspects of the invention are preferable. That is, in the thin film forming apparatus according to the first aspect, the effect is further improved if the substrate deflection angle when the substrates are staggered is 60 to 120 degrees (the invention of the second aspect). Further, in the thin film forming apparatus according to claim 1 or 2, the distance between the roll axis centers of two guide rolls adjacent to each other across the lines A and B is set to １ ／ or less of the width dimension of the substrate ( The invention of claim 3). According to this, as described later in detail, even when the width of the substrate is large, it is possible to suppress the occurrence of the loosening of the substrate, and the effect of preventing the occurrence of wrinkles is large.
[0030]
4. The thin film forming apparatus according to claim 1, further comprising: a sputtering target and a substrate parallel to the substrate with the substrate extending between two guide rolls on the adjacent A and B lines. A heater for heating is arranged, and at least two targets between the adjacent guide rolls at the front stage and between the adjacent guide rolls at the rear stage have a surface facing the substrate, one of which is on the substrate front side and the other is on the substrate back surface side. (The invention of claim 4).
[0031]
Furthermore, as in the invention according to claim 5, in the thin film forming apparatus according to claim 4, the unwinding roll or the winding roll and the substrate are arranged in parallel with the substrate with a substrate extending between the guide rolls. It is assumed that a heater for preheating is provided.
[0032]
Details of the configuration and the operation and effect of the inventions of claims 4 and 5 will be described later together with the embodiments.
[0033]
The application of the invention is most effective in forming a thin film of a thin film solar cell. That is, in the thin film forming apparatus according to any one of claims 1 to 5, the predetermined thin film is formed by forming a thin film of an electrode layer in a thin film solar cell (the invention of claim 6).
[0034]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0035]
FIG. 1 relates to a schematic schematic configuration of an embodiment of the present invention, and mainly shows a schematic schematic configuration of a substrate transport system, and FIG. 2 shows a schematic perspective view of the substrate transport system in FIG. 1 and 2, the same reference numerals are given to the same functional members as those shown in FIGS. 5 and 6, and the detailed description is omitted.
[0036]
The apparatus shown in FIG. 1 is isolated from the outside by a closed container 20, and the inside of the container is evacuated by an exhaust pump 8. The film substrate 10 wound around the unwinding roll 11a is set in this container, the substrate is laid over a plurality of guide rolls 5, and the terminal end of the film substrate is fixed to the winding roll 12a. The substrate 10 is transported by the rotation of the feeding roll 6 and the press roll 7 in contact with the same, and a thin film forming process is performed in the closed container 20 while being transported between the unwinding and winding rolls. In FIG. 1, an illustration of an apparatus for forming a thin film is omitted.
[0037]
FIG. 1 shows an embodiment in which the arrangement of the guide rolls 5 for transporting the film substrate as described in claim 1 suppresses the generation of wrinkles during film formation. That is, the center of the roll axis of the plurality of guide rolls 5 is arranged in two rows on lines A and B in the figure. The axial centers of the guide rolls 5 in each row are arranged on the same straight line for each row, and straight lines A and B connecting the axial centers of the two rows are parallel to each other. Further, the guide rolls 5 in each row are arranged in the middle of two rolls in another row facing each other, and are arranged so as to be alternated.
[0038]
In this case, the film substrate 10 is transported between the guide rolls 5 so as to form a “<” shape. That is, the substrate 10 is transported so as to be alternately staggered between the guide rolls on the A and B lines, and a predetermined tension is applied to the substrate extending between two guide rolls on the adjacent A and B lines. The distance (d) between A and B is determined so that (shown C and D) is added.
[0039]
By doing as described above, the tension applied to the substrate between the guide rolls 5 is superimposed on the substrate 10 in addition to the tension (transport tension) applied in the substrate transport direction by the pair of press rolls 7 and the feeding roll 6. 1, a pulling force acts as shown by arrows C and D in FIG. As a result, even when the transport tension is small, the substrate is stretched, and the substrate surface located between the guide rolls 5 is prevented from wrinkling and becomes flat. If the transport tension is too high, the pulling forces indicated by C and D become too large, and wrinkles parallel to the transport direction are generated. Therefore, it is necessary to select an appropriate value. The tensile force is preferably, for example, 2 kgf / m (substrate width).
[0040]
In FIG. 1, it is more preferable to arrange the guide rolls 5 so that the substrate deflection angle α when the substrates are staggered is in the range of 60 degrees to 120 degrees. Further, as will be described in detail later, as shown in FIG. 2, the distance p between the center of the roll axes of two adjacent guide rolls is preferably not more than ４ of the width L of the substrate.
[0041]
As described above, by devising the configuration of the guide roll, the film substrate can be suitably supported and wrinkles can be prevented without providing a complicated tension control mechanism. In addition, the arrangement of the guide rolls may be vertical or horizontal. However, as shown in FIG. 2, it is preferable to arrange the guide rolls horizontally and to transport the film substrate 10 vertically from the top to the bottom along the guide rolls in order to reduce the transport tension. . This is because the substrate tends to extend in the vertical direction due to its own weight, so that the mechanical force applied for generating tension can be reduced. In addition, by forming the transfer path in the shape of a square, the size of the vacuum container can be reduced, and the size of the entire apparatus can be reduced.
[0042]
Next, as described above, the effect of setting the distance p between the center of the roll axis of the guide roll to 1/4 or less of the width L of the substrate will be described. In the embodiment shown in FIGS. 1 and 2, when the center distance p between the roll axes is increased, the film substrate is loosened (bent), and the effect of preventing the occurrence of wrinkles is reduced. A practical substrate width is about 0.5 to 1.5 m, and for the film substrate in this range, the slack of the film substrate and the state of the substrate between the rolls are confirmed by arbitrarily changing the distance p between the roll axes. did. As an example, FIG. 3 shows the result of measurement on a film substrate having a width of 500 mm.
[0043]
FIG. 3 is a view showing an experimental result of a relationship between a roll axis center distance (mm) and a substrate slack (mm). When the center distance between the roll axes is 1000 mm, which is twice the film width, the slack of the substrate is about 18 mm. By setting the distance to 125 mm, which is one quarter of the substrate width, the slack of the substrate is almost zero. It became. From this result, it was found that the distance p between the center of the roll axis of the guide roll is preferably equal to or less than １ ／ of the width L of the substrate.
[0044]
Next, an embodiment according to claims 4 to 6 will be described with reference to FIG. FIG. 4 shows an embodiment in which the lower electrode layer 64 is formed on the front side of the substrate 61 of the thin-film solar cell shown in FIG. 8, and the connection electrode layer 63 is formed on the back side by a roll-to-roll sputtering apparatus.
[0045]
In the conventional roll-to-roll sputtering apparatus, when forming the electrode layers on both surfaces of the film substrate 10, first, the electrode layers are formed only on one surface, and then the inside of the vacuum sealed container is once opened to the atmosphere. After that, the front and back of the substrate were exchanged, and the chamber was evacuated again and, after reaching a predetermined degree of vacuum, an electrode layer was formed on the other surface. The conventional method has a problem in that after the first electrode layer is formed, the substrate is warped to the side where the film is formed, and distortion is caused by the film stress.
[0046]
According to the embodiment of FIG. 3, in addition to the problem of the occurrence of normal wrinkles, the problem associated with the replacement of the front and back of the substrate as described above can be solved at the same time. That is, according to FIG. 3, the film formation of the electrode layer during the passage through the guide roll 5 is performed by the heater 30 and the sputter target 14 a which are installed to face each other in a position parallel to each other with the film substrate 10 interposed therebetween. I do. According to this method, the front and back surfaces of the film substrate can be formed alternately and sequentially between the guide rolls 5, and the operation of exchanging the front and back surfaces of the substrate is not required. Can be suppressed.
[0047]
The thickness of the thin film formed by one sputter target 14a is preferably about 100 nm, and the heating of the substrate by the heater 30 is preferably about 300 ° C. When a predetermined thickness of the electrode layer is formed, it can be dealt with by arranging an arbitrary number of the heaters 30 and the sputter targets 14a.
[0048]
In a portion where film formation is not performed, the preliminary heater 31 performs heating, and the guide roll 5 itself is also heated, so that a change in temperature applied to the substrate 10 can be reduced. With the above-described configuration, it is possible to form electrode films on both surfaces of the substrate and reduce the film stress remaining on the electrode layer by one transfer of the substrate.
[0049]
【The invention's effect】
According to the present invention, as described above, an unwinding roll and a winding roll for a film substrate, and a roll for winding the film substrate and disposed between the two rolls, for guiding the transfer of the substrate and applying a predetermined tension to the substrate. In a roll transport type thin film forming apparatus provided with a substrate transport means having a plurality of guide rolls and a thin film formation processing chamber for forming a predetermined thin film on a substrate, the plurality of guide rolls are separated by a predetermined distance (d ) Are arranged such that the center of the roll axis of each of the plurality of guide rolls is on a line parallel to each other (line A, B) and the center of the roll axis on the line A, B is different from each other. Further, the substrate is transported alternately between the guide rolls on the A and B lines so as to be staggered, and is fixed to the substrate extending between two guide rolls on the adjacent A and B lines. Tension is applied Sea urchin, with the construction in which the defining a predetermined distance (d),
A thin film forming apparatus that suppresses the problem of wrinkling of a film substrate during a manufacturing process, improves manufacturing yield and quality stability, and further reduces the size of the apparatus, and in particular, a thin film solar cell manufacturing apparatus Can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an embodiment of the present invention. FIG. 2 is a perspective view of a roll conveyance system in FIG. 1. FIG. 3 is a diagram showing an experimental result of a relationship between a roll axis center distance and substrate slack. FIG. 5 is a schematic configuration diagram of an embodiment of a roll-to-roll sputtering apparatus according to the present invention. FIG. 5 is an enlarged schematic configuration diagram of a conventional thin film formation processing chamber. FIG. 6 shows an example of a detailed configuration of a conventional roll-to-roll sputtering apparatus. FIG. 7 is a diagram generally showing an example of a manufacturing process of a thin-film solar cell and various devices. FIG. 8 is a perspective view illustrating a schematic configuration of a thin-film solar cell.
5: guide roll, 6: payout roll, 7: press roll, 10: substrate, 11a: unwinding roll, 12a: winding roll, 14a: sputtering target, 30: heating heater, 31: preliminary heater.

Claims (6)

Substrate transport means having a roll for unwinding and a roll for winding a film substrate, and a plurality of guide rolls disposed between the two rolls for guiding the transport of the substrate and applying a predetermined tension to the substrate And, in a roll transport type thin film forming apparatus comprising a thin film forming processing chamber for forming a predetermined thin film on the substrate,
The plurality of guide rolls are arranged on a line (A, B line) having a predetermined interval (d) and parallel to each other with the center of the roll axis of each of the plurality of guide rolls, and on the A, B line. Are arranged so that the center of the roll axis is different from each other,
Further, the substrate is transported alternately between the guide rolls on the A and B lines in a staggered manner, and a predetermined tension is applied to the substrate extending between two guide rolls on the adjacent A and B lines. Characterized in that the predetermined interval (d) is set so as to add the following. 2. The thin film forming apparatus according to claim 1, wherein a substrate deflection angle when the substrates are staggered is 60 to 120 degrees. 3. 3. The thin film forming apparatus according to claim 1, wherein a distance between roll axis centers of two guide rolls adjacent to each other across the lines A and B is equal to or less than 1/4 of a width of the substrate. Thin film forming apparatus. 4. The thin film forming apparatus according to claim 1, wherein a target for sputtering and a substrate for heating are arranged in parallel with the substrate with the substrate extending between two guide rolls on the adjacent A and B lines. And at least two targets between the adjacent guide rolls at the former stage and between the adjacent guide rolls at the latter stage, one of the surfaces facing the substrate, one on the substrate front side, and the other on the substrate back side. A thin film forming apparatus characterized by being arranged as described above. 5. The thin film forming apparatus according to claim 4, wherein a heater for substrate preheating is disposed in parallel with the substrate with the substrate extending between the unwinding roll or the winding roll and the guide roll. Thin film forming apparatus. 6. The thin film forming apparatus according to claim 1, wherein the predetermined thin film is formed by forming a thin film of an electrode layer in a thin film solar cell.

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