WO2015145948A1

WO2015145948A1 - Semiconductor wafer transfer apparatus and solar cell manufacturing method using same

Info

Publication number: WO2015145948A1
Application number: PCT/JP2015/000706
Authority: WO
Inventors: 博喜湯川
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2014-03-28
Filing date: 2015-02-17
Publication date: 2015-10-01
Also published as: JP2017098275A

Abstract

A flat first suction surface (14a) and a flat second suction surface (14b) for sucking a semiconductor wafer are disposed on the upper surface side of a first arm (10a) and a second arm (10b), respectively. A connecting member (12) connects together one side end of the first arm (10a) and one side end of the second arm (10b). The first suction surface (14a) and the second suction surface (14b) of respective first arm (10a) and second arm (10b) are sloped such that the inner sides facing each other are lower than the outer sides that are on the sides opposite to the inner sides.

Description

Semiconductor wafer transfer device and method for manufacturing solar cell using the same

The present invention relates to a solar cell manufacturing technique, and more particularly, to a semiconductor wafer transfer device for transferring a semiconductor wafer and a solar cell manufacturing method using the same.

In the manufacturing process of a liquid crystal display device, multiple glass substrates can be accommodated in multiple upper and lower stages at predetermined intervals before the process of forming a transparent electrode film on a glass substrate or forming a thin film transistor. Stored in a simple substrate cassette. A substrate pick is used to remove the glass substrate from the substrate cassette. The pick-up for picking up a substrate includes a pair of arms, and the substrate lifting surface of each arm is formed to have a mountain shape in a cross section perpendicular to the loading / unloading direction of the arm with respect to the cassette (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 9-27533

In the manufacturing process of the solar cell, an etching process or the like is performed on the semiconductor wafer. A plurality of semiconductor wafers subjected to the etching process are also stored in the cassette. At that time, both edge portions of the semiconductor wafer are supported by the cassette. Since the thickness of the semiconductor wafer that has been subjected to the etching process is thinner than the thickness of the original semiconductor wafer, the central portion of the semiconductor wafer is more likely to bend downward than before the etching process. In a situation where such semiconductor wafers are already stored in the cassette, contact between the semiconductor wafers should be suppressed when a new semiconductor wafer is inserted into the cassette. On the other hand, when a semiconductor wafer is inserted into or removed from a cassette, a semiconductor wafer transfer device is used. In particular, the semiconductor wafer is attracted to the upper surface side of the arm in the semiconductor wafer transfer device. However, when the cross section of the arm has a chevron shape, it is possible to obtain an adsorption force that is insufficient for the adsorption of the semiconductor wafer.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique for suppressing contact between semiconductor wafers when a semiconductor wafer is stored in a cassette when a solar cell is manufactured. There is.

In order to solve the above-described problems, a semiconductor wafer transfer apparatus according to an aspect of the present invention includes a pair of arms each having a flat suction surface for sucking a semiconductor wafer disposed on the upper surface side, and a pair of arms. And a connecting member for connecting the respective one side ends. In each of the suction surfaces of the pair of arms, the inner sides facing each other are inclined so as to be lower than the outer side opposite to the inner side.

Another aspect of the present invention is a method for manufacturing a solar cell. The method includes the steps of etching a semiconductor wafer, and storing the etched semiconductor wafer in a cassette in which a plurality of semiconductor wafers can be juxtaposed by supporting both edge portions of the semiconductor wafer. And a step of moving the cassette in which the etched semiconductor wafer is housed, and a step of forming an amorphous silicon layer on the semiconductor wafer housed in the moved cassette. In the storing step, the suction surfaces arranged on the upper surface side of each of the pair of arms included in the semiconductor wafer transfer apparatus, and the inner sides facing each other are lower than the outer side opposite to the inner side. The semiconductor wafer is adsorbed on the inclined adsorption surface.

According to the present invention, when a solar cell is manufactured, contact between semiconductor wafers when the semiconductor wafer is stored in a cassette can be suppressed.

It is a flowchart which shows the manufacturing procedure of the solar cell which concerns on embodiment. 2A to 2E are views showing cross sections of the solar cell in each step of the manufacturing procedure of the solar cell shown in FIG. It is a top view which shows the structure of the semiconductor wafer transfer apparatus which concerns on embodiment. It is sectional drawing which shows the structure of the semiconductor wafer conveyance apparatus of FIG. It is a top view which shows the structure at the time of adsorb | sucking a semiconductor wafer to the semiconductor wafer conveyance apparatus of FIG. It is sectional drawing which shows the structure of the semiconductor wafer conveyance apparatus of FIG. It is sectional drawing which shows the structure of the cassette which concerns on embodiment of this invention.

Before describing the embodiment specifically, an outline will be described. The present embodiment relates to a process of moving an etched semiconductor wafer to a vacuum film forming apparatus in the course of manufacturing a solar cell. A cassette that can store a plurality of semiconductor wafers is used for the movement. On both side surfaces inside the cassette, support shelves are provided for supporting the respective edge portions of the semiconductor wafer. The support shelves are provided in a plurality of stages in the vertical direction of the side surface in order to support a plurality of semiconductor wafers. As described above, since the etched semiconductor wafer is very thin, the center portion bends downward when supported by the support shelf. When semiconductor wafers are inserted in order from the upper support shelf, there is a possibility that a new semiconductor wafer to be inserted comes into contact with the central portion of the already inserted semiconductor wafer. In order to cope with this, in this embodiment, when the semiconductor wafer is inserted into the cassette, the semiconductor wafer is attracted to the attracting surfaces of the pair of arms in the semiconductor wafer transfer apparatus. Further, the suction surface is inclined so that the method of bending the semiconductor wafer sucked by the semiconductor wafer transfer device is close to the method of bending the semiconductor wafer already stored in the cassette.

FIG. 1 is a flowchart showing a manufacturing procedure of the solar cell according to the embodiment. 2A to 2E are views showing cross sections of the solar cell in each step of the manufacturing procedure of the solar cell shown in FIG. In the slicing step, a semiconductor wafer is generated by slicing the ingot (S10). In the case of a solar cell, a semiconductor wafer that has been sliced from an ingot is often used. On the other hand, as shown in FIG. 2A, the semiconductor wafer 20 has surface damage and contamination due to scratches generated during slicing.

In the removing process, the surface damage and contamination of the semiconductor wafer are removed (S12). In the removing step, about 10 to 20 μm of the surface of the semiconductor wafer is etched. As shown in FIG. 2B, scratches on the surface of the semiconductor wafer 20 are removed. If the etching by the removal process is insufficient, the open circuit voltage (Voc) is lowered. The open circuit voltage is a voltage in a state where nothing is connected between the positive electrode and the negative electrode of the solar cell.

In the etching process, the semiconductor wafer is etched to form an uneven shape on the light receiving surface (S14). As shown in FIG. 2 (c), even if light that escapes to the outside by a single reflection is formed on the surface of the semiconductor wafer 20 by forming an uneven shape on the surface of the semiconductor wafer 20, it is inclined. The surface can be reflected several times and introduced into the semiconductor wafer 20. As a result, more light can be absorbed inside the solar cell, and the characteristics of the solar cell are improved. Note that the thickness of the semiconductor wafer is further reduced by performing the etching.

In the storing step, the etched semiconductor wafer is stored in the cassette by using a semiconductor wafer transfer device (not shown) (S16). In general, in a solar cell manufacturing factory, manufacturing of a solar cell is automated, and loading and unloading of a semiconductor wafer to a vacuum film forming apparatus described later is automated using a robot or the like. A semiconductor wafer transfer device is used during such loading and unloading of a semiconductor wafer. The semiconductor wafer transfer apparatus includes a pair of arms, and the etched semiconductor wafer is adsorbed to the adsorption surfaces arranged on the upper surfaces of the pair of arms. Here, since the inner surfaces facing each other on the adsorption surfaces of the pair of arms are inclined so as to be lower than the outside, the semiconductor wafer adsorbed by the pair of arms is near the central portion of the pair of arms. Sag downward.

The cassette can juxtapose a plurality of semiconductor wafers by supporting both edge portions of the semiconductor wafer. By supporting both edge portions, the semiconductor wafer housed in the cassette bends downward near the central portion, similar to the semiconductor wafer placed on the pair of arms. Since both have the same shape, when the semiconductor wafer adsorbed by the semiconductor wafer transfer device is inserted into the cassette, the contact between the semiconductor wafer and the already accommodated semiconductor wafer is prevented. In the moving process, the cassette in which the etched semiconductor wafer is stored is moved to the vacuum film forming apparatus (S18).

In the forming step, an amorphous silicon layer is formed on the semiconductor wafer stored in the moved cassette by a vacuum film forming apparatus (S20). As shown in FIG. 2D, an n-type amorphous silicon layer 30 is formed on a semiconductor wafer 20 of an n-type crystalline silicon substrate, and is opposite to the surface of the semiconductor wafer 20 on which the n-type amorphous silicon layer 30 is formed. A p-type amorphous silicon layer 32 is formed on the surface. A passivation layer may be provided between the semiconductor wafer 20 and the n-type amorphous silicon layer 30 and between the semiconductor wafer 20 and the p-type amorphous silicon layer 32. For example, substantially intrinsic i-type amorphous silicon, silicon nitride, or silicon oxide is used for the passivation layer. The n-type amorphous silicon layer 30 and the p-type amorphous silicon layer are formed using a vacuum film formation method such as a CVD method, for example. Transparent

conductive layers

34 and 36 are provided on the n-type amorphous silicon layer 30 and the p-type amorphous silicon layer 32. The transparent

conductive layers

34 and 36 include, for example, indium oxide, tin oxide, and zinc oxide. The transparent

conductive layers

34 and 36 are formed by using a vacuum film forming method such as a sputtering method, for example. In the printing process, silver paste electrodes are printed on the light receiving surface and the back surface (S22). As shown in FIG. 2E, a silver paste electrode 38 is formed on the transparent

conductive layers

34 and 36 by screen printing. The silver paste electrode 38 may be cured by baking or drying.

FIG. 3 is a top view showing the configuration of the semiconductor wafer transfer apparatus 100 according to the embodiment of the present invention. The semiconductor wafer transfer apparatus 100 includes a first arm 10a, a second arm 10b, collectively referred to as an arm 10, a connecting member 12, a first suction surface 14a, generally referred to as a suction surface 14, and a second suction surface 14b.

The first arm 10a and the second arm 10b are arranged substantially in parallel to form a pair of arms 10. The connecting member 12 connects one end of each of the pair of arms 10. It can be said that such a connecting member 12 supports one end of each of the first arm 10a and the second arm 10b. Therefore, the arm 10 is protruded from the connecting member 12 in the semiconductor wafer transport direction.

The first suction surface 14a is disposed on the upper surface side of the first arm 10a, and the second suction surface 14b is disposed on the upper surface side of the second arm 10b. The suction surface 14 includes holes (not shown), and the semiconductor wafer is sucked onto the suction surface 14 by sucking air from the holes. By such adsorption, a semiconductor wafer is placed on the pair of arms 10. In order to describe the suction surface 14 in detail, FIG. 4 is used. FIG. 4 is a cross-sectional view taken along the line A-A ′ showing the configuration of the semiconductor wafer transfer apparatus 100. The first suction surface 14a and the second suction surface 14b are flat surfaces and are inclined so that the inner sides facing each other are lower than the outer side opposite to the inner side. Therefore, the height of the 1st adsorption | suction surface 14a and the 2nd adsorption | suction surface 14b at the time of arrange | positioning each arm 10 horizontally becomes lower inside than the outer side. Although the structure of the surface opposite to the first suction surface 14a and the second suction surface 14b of the arm 10 is not particularly limited, it is preferable to incline similarly to the first suction surface 14a and the second suction surface 14b.

FIG. 5 is a top view showing a configuration when the semiconductor wafer 20 is attracted to the semiconductor wafer transfer apparatus 100. This corresponds to step 16 in FIG. 1, and the semiconductor wafer 20 is placed on the semiconductor wafer transfer apparatus 100 shown in FIG. The semiconductor wafer 20 includes a central portion 22, a first end side edge portion 24 a and a second end side edge portion 24 b collectively referred to as an end side edge portion 24. The semiconductor wafer 20 here is etched as described above.

The suction surfaces 14 of the pair of arms 10 are in contact with inner portions of the first end side edge portion 24a and the second end side edge portion 24b facing each other in the semiconductor wafer 20 to be transported. Further, it is desirable that the semiconductor wafer 20 be placed on the pair of arms 10 so as to be line symmetric with respect to the symmetry axis of the pair of arms 10. Therefore, as a relative positional relationship between the pair of arms 10 and the semiconductor wafer 20, the distance between the first end side edge 24a and the first arm 10a, and the distance between the second end side edge 24b and the second arm 10b. Are arranged in contact with the semiconductor wafer 20 so that they are substantially the same.

With this arrangement, the central portion 22 of the semiconductor wafer 20 passes through the axis of symmetry. The central portion 22 is a central portion of the semiconductor wafer 20 and includes a center of gravity. The central portion 22 does not have to be a single point, and may be a region having a predetermined area. In FIG. 5, the length of the pair of arms 10 is shorter than the vertical length of the semiconductor wafer 20. Depending on the semiconductor wafer 20 to be transferred, the length of the pair of arms 10 may be longer than the vertical length of the semiconductor wafer 20.

FIG. 6 is a B-B ′ sectional view showing the configuration of the semiconductor wafer transfer apparatus 100. The semiconductor wafer 20 is adsorbed by the first arm 10a on the first adsorbing surface 14a and adsorbed by the second arm 10b on the second adsorbing surface 14b. Between the first suction surface 14a and the second suction surface 14b, the semiconductor wafer 20 warps in a concave state with the central portion 22 as the center. Therefore, the center part 22 is arrange | positioned below the lowest part of the 1st adsorption | suction surface 14a and the 2nd adsorption | suction surface 14b in the up-down direction of FIG. On the other hand, as a result of the concave warp centered on the central portion 22, the first end side edge portion 24a and the second end side edge portion 24b are higher than the uppermost portions of the first suction surface 14a and the second suction surface 14b. Placed in.

Here, the inclination angle of the first suction surface 14a and the second suction surface 14b and falling from the outer side to the inner side maintains the continuity of the warpage of the concave state due to the weight of the semiconductor wafer 20. It is considered to be an angle. Further, as described above, since the first suction surface 14a and the second suction surface 14b are flat, the contact area with the semiconductor wafer 20 is widened, and the suction force of the semiconductor wafer 20 is increased.

FIG. 7 is a cross-sectional view showing a configuration of the cassette 50 according to the embodiment. This corresponds to step 16 in FIG. The cassette 50 includes a first support shelf 52a and a second support shelf 52b collectively referred to as a support shelf 52. In order to clarify the drawing, reference numerals are given only to the components related to one semiconductor wafer 20, and the reference numerals are omitted for the rest. Moreover, since FIG. 7 is shown in the same direction as FIG. 6, the back direction of the figure corresponds to the upward direction of FIG. A first support shelf 52a and a second support shelf 52b are protruded in a plurality of stages at intervals in the vertical direction of FIG. 7 on both side walls in the cassette 50. The cassette 50 includes a plurality of semiconductor wafers. 20 can be juxtaposed in the vertical direction.

The semiconductor wafer transfer apparatus 100 shown in FIGS. 5 and 6 is attached to a transfer robot (not shown) and inserted between the first support shelf 52a and the second support shelf 52b in the cassette 50. More specifically, the semiconductor wafer 20 is inserted to a predetermined position by feeding the pair of arms 10 from the near side of FIG. Thereafter, the pair of arms 10 is slightly lowered, the first support shelf 52a supports the first end side edge 24a, and the second support shelf 52b supports the second end side edge 24b. The semiconductor wafer 20 is stored in the cassette 50.

Next, the semiconductor wafer transfer device 100 is moved so as to pull out the pair of arms 10 from the cassette 50, taking care not to contact the semiconductor wafer 20 stored on the lower side. The semiconductor wafer 20 thus housed in the first support shelf 52a and the second support shelf 52b is supported by the first end side edge portion 24a and the second end side edge portion 24b, so that the central portion 22 is formed. Bends to hang down. The warp of the semiconductor wafer 20 at this time is a concave direction similar to the warp generated when the semiconductor wafer 20 is placed on the pair of arms 10 and is warped by the same weight. Therefore, the upper surface of the semiconductor wafer 20 on the pair of arms 10 does not contact the semiconductor wafer accommodated in the upper stage. Further, the lower surface of the semiconductor wafer 20 on the pair of arms 10 does not contact the semiconductor wafer housed in the lower stage.

According to the present embodiment, the flat suction surface is inclined so that the inner side is lower than the outer side, so that a sufficient suction force for placing the semiconductor wafer can be obtained. Further, since the inner side is inclined so as to be lower than the outer side, when the semiconductor wafer is placed, the semiconductor wafer can be bent downward at the central portion between the pair of arms. Further, since the semiconductor wafer is bent downward in the central portion between the pair of arms, the same shape as that of other semiconductor wafers already stored in the cassette can be realized. Also, since the semiconductor wafer to be inserted from now on has the same shape as other semiconductor wafers already stored in the cassette, the semiconductor wafer when storing the semiconductor wafer in the cassette when manufacturing a solar cell. The contact between them can be suppressed. Moreover, since the surface opposite to the suction surface of the arm is also inclined similarly to the suction surface, contact with the arm semiconductor wafer can be further suppressed.

Further, according to the present embodiment, the semiconductor wafer is transferred using the arm having the suction surface inclined so that the inner side is lower than the outer side during the period from the etching step S14 to the forming step S20 where the semiconductor wafer is thinnest. To do. Thereby, when manufacturing a solar cell, the contact between the semiconductor wafers when the semiconductor wafers are stored in the cassette can be further suppressed.

The outline of one embodiment of the present invention is as follows. The semiconductor wafer transfer apparatus 100 according to an aspect of the present invention includes a pair of arms 10 each having a flat suction surface 14 for sucking the semiconductor wafer 20 disposed on the upper surface side, and one side of each of the pair of arms 10. And a connecting member 12 for connecting the ends. In each suction surface 14 of the pair of arms 10, the inner sides facing each other are inclined so as to be lower than the outer side opposite to the inner side.

Another aspect of the present invention is a method for manufacturing a solar cell. In this method, the semiconductor wafer 20 is etched in a cassette 50 in which a plurality of semiconductor wafers 20 can be juxtaposed by supporting a step of etching the semiconductor wafer 20 and both edge portions of the semiconductor wafer 20. A step of moving the cassette 50 storing the etched semiconductor wafer 20 and a step of forming an amorphous silicon layer on the semiconductor wafer 20 stored in the moved cassette 50. Prepare. In the storing step, the suction surfaces 14 arranged on the upper surface side of each of the pair of arms 10 included in the semiconductor wafer transfer apparatus 100, and the inner side facing each other is more than the outer side opposite to the inner side. The semiconductor wafer 20 is sucked onto the suction surface 14 inclined so as to be lowered.

The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to each component or combination of each processing process, and such modifications are within the scope of the present invention. .

In the embodiment, an amorphous silicon solar cell is manufactured as the solar cell. However, the present invention is not limited to this. For example, a crystalline silicon solar cell may be manufactured as a solar cell. At that time, a pn junction is formed by thermally diffusing phosphorus or boron instead of forming the amorphous silicon layer in the vacuum film forming apparatus. According to this modification, the present embodiment can be used for manufacturing various types of solar cells.

10 arms, 12 connecting members, 14 suction surfaces, 20 semiconductor wafers, 22 central part, 24 end side edges, 50 cassettes, 52 support shelves, 100 semiconductor wafer transfer device.

Claims

A pair of arms each having a flat suction surface for adsorbing a semiconductor wafer disposed on the upper surface side;
A connecting member that connects one end of each of the pair of arms;
2. A semiconductor wafer transfer apparatus according to claim 1, wherein each of the suction surfaces of the pair of arms is inclined such that inner sides facing each other are lower than an outer side opposite to the inner side.
Etching a semiconductor wafer; and
Storing the etched semiconductor wafer in a cassette in which a plurality of semiconductor wafers can be juxtaposed by supporting both edge portions of the semiconductor wafer;
Moving the cassette containing the etched semiconductor wafer;
A step of forming an amorphous silicon layer on the semiconductor wafer housed in the moved cassette,
In the storing step, the suction surfaces arranged on the upper surface side of each of the pair of arms included in the semiconductor wafer transfer apparatus and the inner sides facing each other are lowered from the outer side opposite to the inner side. A method for manufacturing a solar cell, comprising adsorbing a semiconductor wafer on an inclined suction surface.