JP2010199242A - Method for manufacturing integrated thin-film solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a solar cell capable of efficiently manufacturing an integrated thin-film solar cell. <P>SOLUTION: The method for manufacturing the integrated thin film solar cell includes: providing a solar cell substrate on which at least a lower electrode layer, a light absorption layer, and an upper electrode layer are formed, on an insulating substrate (1); patterning to form a plurality of grooves on the upper electrode layer surface in the depth from the upper electrode layer side to the lower electrode layer surface in a region to be a functional region of individual solar cell mutually divided in a post process of the solar cell substrate (2); wide-patterning to expose the lower electrode layer by removing each layer from the upper electrode side to the lower electrode layer surface of the both sides of the region expanding in parallel with the plurality of grooves and to be the functional region of the individual solar cell (3); scribing a brittle substrate (4); and breaking (5). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a method for manufacturing an integrated thin film solar cell, and particularly to a method for manufacturing a chalcopyrite compound integrated thin film solar cell. Here, the chalcopyrite compound includes compound semiconductors such as CIGS [Cu (In, Ga) Se ₂ ], CIGSS [Cu (In, Ga) (Se, S) ₂ ], CIS [CuInS ₂ ] and the like.

  In thin-film solar cells that use a compound semiconductor such as a chalcopyrite compound as the light absorption layer, a lower electrode layer, a light absorption layer, a high-resistance buffer layer, and an insulation layer and an upper electrode layer as necessary are sequentially formed on the insulating substrate. In the thin film laminate, in order to connect the lower electrode layer and the upper electrode layer by separating the groove for separating the lower electrode layer [lower electrode separation groove], the light absorption layer and the high-resistance buffer layer (and the insulating layer) Forming a plurality of unit cells by forming a groove [interelectrode contact groove], an upper electrode layer, a (insulating layer) and a high resistance buffer layer, and a groove [upper electrode separation groove] separating the light absorption layer. It is common to have integrated structures connected in series.

  A conventional method for producing a chalcopyrite compound-based integrated thin film solar cell will be described (Patent Documents 1 to 3). FIG. 6 is a schematic diagram showing a manufacturing process of a CIGS thin film solar cell. First, as shown in FIG. 6A, a Mo electrode layer 2 serving as a plus-side lower electrode is formed on an insulating substrate 1 made of soda lime glass (SLG) or the like by sputtering, and then a light absorption layer is formed. A groove S for lower electrode separation is formed by scribing the previous solar cell substrate.

  Thereafter, as shown in FIG. 6B, a light absorption layer 3 made of a CIGS thin film is formed on the Mo electrode layer 2 by vapor deposition, sputtering, or the like, and a ZnS thin film or the like for heterojunction is formed thereon. The buffer layer 4 made of is formed by the CBD method (chemical bath deposition method), and the insulating layer 5 made of a ZnO thin film is formed thereon. And, for the inter-electrode contact that reaches the Mo electrode layer 2 by scribing at a position that is a predetermined distance in the lateral direction from the groove S for separating the lower electrode with respect to the thin film solar cell substrate before forming the upper electrode layer A groove M1 is formed.

  Subsequently, as shown in FIG. 6C, a transparent electrode layer 6 as an upper electrode made of a ZnO: Al thin film is formed on the insulating layer 5, and each functional layer necessary for power generation using photoelectric conversion is formed. An upper electrode separation groove M2 that reaches the lower Mo electrode layer 2 is formed by scribing, using the solar cell substrate provided.

Japanese Patent Laid-Open No. 11-31815 JP 2002-94089 A JP 2004-115356 A

  However, in order to manufacture an integrated thin film solar cell, it is necessary to alternately perform a process of forming at least four types of thin films on an insulating substrate and at least three processes of forming grooves in each thin film, There was a limit to improving manufacturing efficiency.

  The present invention manufactures a solar cell substrate (mother substrate) that includes a plurality of regions that ultimately become individual solar cell functional regions, and collectively performs thin film formation and groove formation, It aims at improving the manufacturing efficiency of a thin film solar cell.

  In particular, an object is to improve the efficiency of the entire solar cell manufacturing process by increasing the efficiency of the process from formation of all functional layers (thin films) to obtaining individual solar cells.

The manufacturing method of the integrated thin film solar cell of the present invention made to solve the above problems
(1) providing a solar cell substrate in which at least a lower electrode layer, a light absorption layer and an upper electrode layer are formed on an insulating substrate;
(2) Each of the regions that are divided from each other in the subsequent step of the solar cell substrate to become a functional region of each individual solar cell has a depth from the upper electrode layer side to the lower electrode layer surface, and is the same on the upper electrode layer surface. A patterning step of forming a plurality of grooves extending parallel to each other in the direction;
(3) Each layer extending in parallel with the plurality of grooves formed in the patterning step and extending from the upper electrode side to the lower electrode layer surface of the region located on both sides of the region serving as the functional region of the individual solar cell. Wide patterning process to remove and expose the lower electrode layer,
(4) a scribe step of forming a scribe line in a region where the lower electrode layer is exposed in the wide patterning step; and (5) a break step of breaking along the scribe line.

The manufacturing method of the thin film solar cell of this invention can include the marking process of forming an alignment mark in the said solar cell substrate before the said patterning process as needed. The alignment mark can be formed by laser marking.

The method for manufacturing a thin film solar cell of the present invention is orthogonal to the grooves on both ends of the plurality of grooves formed in the patterning step after the wide patterning step and before the scribe step or after the break step. An insulating process for performing an insulating process may be included in the region in the direction of the current. The insulating process can be performed by removing the functional layer by laser irradiation or mechanical scribing on the part to be insulated.

The thin-film solar cell manufacturing method of the present invention is a through-hole that forms a through-hole penetrating from the upper electrode layer (front surface side) to the insulating substrate (back surface side) outside the region that is insulated after the insulating step. A forming step can be included. A green laser processing apparatus can be used to form the through hole.

The solar cell substrate may be a solar cell substrate in which a high-resistance buffer layer is formed between the light absorption layer and the upper electrode layer, and further insulated between the high-resistance buffer layer and the upper electrode layer. It can be a solar cell substrate on which a layer is formed. The light absorbing layer may be a chalcopyrite compound selected from the group consisting of CIGS, CIGSS, and CIS, the lower electrode layer may be a Mo layer, and the upper electrode layer may be a transparent conductive film. The insulating substrate may be a glass substrate. In the patterning step, the groove processing tool and the solar cell substrate are relatively opposed to each other in the groove forming direction while pressing the tip of the groove processing tool having at least a tip or a plate shape against the groove forming portion on the upper surface of the upper electrode layer. By moving, a groove extending from the upper electrode layer to the lower electrode layer surface can be formed.

In the patterning step, a rod-shaped body and a cutting edge region formed at the tip of the body, the cutting edge region is an elongated rectangular bottom surface, front and rear surfaces rising from the edge of the bottom surface in the short direction, and a bottom surface It consists of a left and right side surface that rises at a right angle from the end in the longitudinal direction and forms a pair of parallel surfaces, and a corner formed by at least one of the front and rear surfaces and the bottom surface is the cutting edge. A grooving tool can be used.

  According to the method for manufacturing a thin-film solar cell of the present invention, after manufacturing a solar cell substrate including a plurality of regions that are divided from each other and become functional regions of individual solar cells, the solar cell substrate is separated into individual solar cells. The functional layer (thin film) and the groove can be formed efficiently.

(Means and effects for solving other problems)
When the through-hole for wiring between the insulating substrate front and back surfaces is formed in the final stage, it is formed at the time of forming the through-hole by heating and cooling in the thin film formation process, which is a concern when forming the through-hole before forming the thin film. It is possible to avoid the occurrence of a problem that the crack extends from the microcrack and adversely affects the strength of the insulating substrate. In particular, when the through-hole is formed by the green laser processing apparatus, there is no adverse effect on the functional region due to generation of particles that becomes a problem in the case of a mechanical drill using water or a mechanical scribe not using water.

Process drawing which shows one Embodiment of the manufacturing method of the integrated thin film solar cell concerning this invention. The perspective view which shows one Embodiment of the patterning means used in the patterning process in this invention. The perspective view which shows one Embodiment of the groove processing tool used in the patterning process in this invention. FIG. 4 is an enlarged bottom view of the grooving tool in FIG. 3. The schematic diagram which shows the attachment inclination angle of the groove processing tool of FIG. 3, and the processing state of the scribe line of the solar cell board | substrate corresponding to it. The schematic diagram which shows the manufacturing process of a general CIGS type thin film solar cell.

Hereinafter, details of the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.
FIG. 1 is a process diagram of an embodiment of a method for producing an integrated thin film solar cell according to the present invention.

(1) Solar cell substrate Provided is a solar cell substrate in which a lower electrode layer, a light absorption layer, a high-resistance buffer layer, and if necessary, an insulating layer and an upper electrode layer are formed on an insulating substrate. In this solar cell substrate, a lower electrode separation groove is formed in the lower electrode layer, and a groove for connecting the lower electrode layer and the upper electrode layer is formed in the light absorption layer, the high-resistance buffer layer, and the insulating layer. However, the groove for separating the upper electrode layer is not formed.
Although not particularly limited, an insulating brittle material substrate such as glass or ceramics can be used as the insulating substrate. As the lower electrode layer, a Mo electrode layer can be usually exemplified. As a light absorption layer, the layer which consists of various compound semiconductors, such as a chalcogenite compound, for example, a CIGS layer, a CIGSS layer, a CIS layer, etc. can be illustrated. Examples of the high resistance buffer layer include a ZnS layer. An example of the insulating layer is a ZnO layer.

(2) Marking step In the marking step, the solar cell substrate is positioned on the solar cell substrate in a subsequent step, and an alignment mark serving as a reference when performing processing such as groove formation is formed. A laser marking device can be used to form the alignment mark. As this laser marking device, a green laser processing device used for forming a through hole in a subsequent step (through hole forming step) can also be used.

(3) Patterning Step Next, in the patterning step, a plurality of grooves for separating the upper electrode are formed. The groove for separating the upper electrode is formed with a depth from the upper electrode layer to the surface of the lower electrode layer. The grooves for separating the upper electrode are usually linear and are formed parallel to each other in one direction. The groove moves the groove processing tool and the solar cell substrate relative to each other in the groove forming direction while pressing the tip of a groove processing tool having at least a plate-like or rod-like tip against the groove forming portion on the upper surface of the upper electrode layer. Thus, it can be formed.

FIG. 2 is a perspective view showing an embodiment of an apparatus configuration (patterning means) that can be used in the patterning step. The patterning means includes a table 18 that is movable in the horizontal direction (Y direction) and that can rotate 90 degrees and angle θ in a horizontal plane, and the table 18 substantially forms a means for holding the solar cell substrate. .

A bridge 19 composed of support pillars 20, 20 on both sides of the table 18 and guide bars 21 extending in the X direction is provided so as to straddle the table 18. The holder support 23 is attached to be movable along a guide 22 formed on the guide bar 21, and moves in the X direction by the rotation of the motor 24.

A scribe head 7 is provided on the holder support 23, and a groove processing tool 8 for scribing the thin film surface of the solar cell substrate W placed on the table 18 is held below the scribe head 7. A holder 9 is provided. The holder 9 can adjust the angle of attachment to the scribe head 7, and the angle between the groove processing tool 8 and the solar cell substrate W can be adjusted by adjusting the angle of attachment.

Cameras 10 and 11 are provided on pedestals 12 and 13 that can move in the X and Y directions, respectively. The pedestals 12 and 13 move on the support base 13 along a guide 15 extending in the X direction. The cameras 10 and 11 can be moved up and down by manual operation, and the focus of imaging can be adjusted. Images taken by the cameras 10 and 11 are displayed on the monitors 16 and 17. The position of the solar cell substrate W is adjusted by imaging the alignment marks formed on the surface of the solar cell substrate W placed on the table 18 with the cameras 10 and 11. Specifically, the alignment marks on the surface of the solar cell substrate W supported by the table 18 are imaged by the cameras 10 and 11, and the position of the alignment mark is specified. Based on the position of the specified alignment mark, a deviation in direction when the surface of the solar cell substrate W is placed is detected, and the deviation is corrected by rotating the table 18 by a predetermined angle.

Each time the table 18 is moved at a predetermined pitch in the Y direction, the scribe head 7 is lowered to move in the X direction with the cutting edge of the groove processing tool 8 pressed against the surface of the solar cell substrate W. The surface of W is scribed along the X direction. When the surface of the solar cell substrate W is scribed along the Y direction, the table 18 is rotated 90 degrees and the same operation as described above is performed.

  3 and 4 show the groove processing tool 8 used in the patterning process. FIG. 3 is a perspective view seen from below, and FIG. 4 is an enlarged view of the bottom surface of the grooving tool 8. This grooving tool is composed of a rod-shaped body and a cutting edge region formed at the tip of the body, the cutting edge region is an elongated rectangular bottom surface, a front surface and a rear surface rising from the edge in the short direction of the bottom surface, It consists of left and right side surfaces that form a pair of parallel surfaces that rise perpendicularly from the longitudinal edges of the bottom surface, and the corner formed by either one of the front and rear surfaces and the bottom surface forms a cutting edge, forming a rectangle The major axis direction of the bottom surface formed is arranged along the moving direction, and the angle formed between the front surface or the rear surface of the blade edge region and the work surface of the solar cell is in the range of 50 to 80 degrees, particularly 65 to 75 degrees. The groove processing is performed by inclining in the traveling direction side.

  That is, the grooving tool 8 is composed of a cylindrical body 81 that is substantially a mounting portion to the scribe head 7 and a cutting edge region 82 that is integrally formed at the tip portion by electric discharge machining or the like. Made of hard material such as alloy or diamond. The blade edge region 82 includes a rectangular bottom surface 83, a front surface 84 and a rear surface 85 rising at right angles from the short side edge of the bottom surface 83, and a left rising from the long edge of the bottom surface 83 at right angles and parallel to each other. , Right side surfaces 88 and 89. Corner portions formed by the bottom surface 83 and the front and rear surfaces 88 and 89 are cutting edges 86 and 87, respectively.

  The left-right width L1 of the bottom surface 83 is preferably 50 to 60 μm, but can be set to 25 to 80 μm according to the required groove width of the scribe. The effective height of the cutting edge region 82, that is, the height L2 of the left and right side surfaces 87, 88 and the front and rear surfaces 84, 85 of the cutting edge region is preferably about 0.5 mm. Furthermore, the diameter of the cylindrical body 81 is preferably about 2 to 3 mm. Note that the body 81 of the grooving tool 8 is not limited to a columnar shape, but may be formed in a quadrangular cross section or a polygonal shape.

  When processing using the groove processing tool 8 described above, the front surface of the cutting edge portion 82 with respect to the solar cell substrate W with the major axis direction of the bottom surface 83 of the cutting edge region 82 along the moving direction of the tool. 84 or the rear surface 85 is attached to the scribe head 7 in a state where it is inclined by a predetermined angle. In this case, the inclination angle is preferably 50 to 80 degrees, particularly 65 to 75 degrees.

  In the above embodiment, the scribing process is performed by moving the scribe head 7 in the X direction. However, since it is sufficient that the scribe head 7 and the solar cell substrate W can move relative to each other, the solar cell substrate W The scribe head 7 may be moved in the X direction and the Y direction in a fixed state, or only the solar cell substrate W may be moved in the X direction and the Y direction without moving the scribe head 7.

(4) Wide patterning step Further, in the wide patterning step, the region extends in parallel with the groove for separating the upper electrode, and is located on both sides of the region that becomes the functional region of individual solar cells separated from each other in the subsequent step. The layers from the upper electrode layer to the lower electrode layer surface in the region to be removed are removed to expose the lower electrode layer. Various jigs (for example, a needle, a flea-like member, a rod-like member, a plate-like member, a blade-like member, a scraper, etc.) can be used for removing each layer (wide patterning).

(5) Scribe process Then, in the scribe process, a scribe line for dividing the insulating substrate is formed between the functional areas in the area where the lower electrode layer surface is exposed in the wide patterning process. Laser scribing can be used to form the scribe line, but it is usually preferable to use a scribing wheel (mechanical scribe). The scribe line may be formed from the upper surface (lower electrode layer surface) side or from the back surface (insulating substrate side) side.

(6) Break process Next, in the break process, the crack formed along the scribe line with the scribe line as an axis is pressed along the scribe line, pressed from the back surface, applied with an impact from the back surface, or subjected to vibration. The solar cell substrate (mother substrate) is separated into individual solar cells by applying a bending moment in the opening direction.

(7) Insulating process An insulating part is formed by removing each functional layer in the direction orthogonal to a groove | channel on the both ends of the groove | channel for upper electrode isolation | separation. The insulating part can be formed by laser irradiation or mechanical scribing. The insulation process may be performed after the break process (after separation into individual solar cells), but after the wide patterning process and before the scribe process (before separation into individual solar cells). Also good.

(8) Through-hole forming step Finally, in the through-hole forming step, a through-hole is formed in a region outside the insulating portion (outside the functional region). The through-hole is used for wiring wiring from the upper and lower electrodes on the front surface side (functional region side) of the insulating substrate to the back surface side of the insulating substrate. Previously, each functional layer and each groove were formed on an insulating substrate on which a through hole had been formed in advance, but the through hole was formed due to the effects of heating and cooling during the formation of each functional layer. There is a problem that the cracks extend from the microcracks formed during the process, and have an adverse effect on the strength and the like of the insulating substrate. By forming the through holes in the final stage, it is possible to avoid the occurrence of problems such as a decrease in strength of the insulating substrate due to the extension of cracks due to heating / cooling during the formation of each functional layer.

  According to the present invention, a solar cell substrate (mother substrate) having a plurality of regions that are divided into individual solar cells in a post process is subjected to a patterning process and a wide patterning process, and then subjected to a scribe process and a break process. Since the solar cells are separated into individual solar cells, the solar cells can be efficiently manufactured as compared with the case where the individual solar cells are individually subjected to the patterning step and the wide patterning step.

  Further, by forming the alignment mark before the patterning step, subsequent steps (patterning step, wide patterning step, scribe step, break step, etc.) can be performed efficiently and accurately.

  Furthermore, by forming through holes after forming the upper electrode layer, heating / cooling at the time of forming each functional layer from microcracks formed at the time of forming the through holes generated when forming the through holes before forming each functional layer, etc. Therefore, it is possible to avoid the occurrence of the problem that the crack extends and adversely affects the strength of the insulating substrate.

  In the patterning step, patterning can be performed smoothly by using a groove processing tool having at least a tip or a plate at the tip. In particular, as shown in FIG. 5, the angle of the cutting edge region of the grooving tool 8 with respect to the front surface 84 or the rear surface 85 and the upper surface (upper electrode layer) of the solar cell substrate W is 50 to 80 degrees, particularly 65 to 75 degrees. By tilting in the direction of travel within the range of, the scribing line breaks off by getting on the removed film debris and bouncing, and the occurrence of irregular thin film peeling due to high pressing load is eliminated. A scribe line having a reproducible width can be formed.

  Furthermore, since the cutting edges 86 and 87 of the grooving tool 8 are formed in two places at the front and rear corners, if one of them is worn or damaged, the other cutting edge is replaced with a new one by changing the mounting direction of the grooving tool 8. Can be used as In addition, when any of the cutting edges is worn, the cutting edge can be repaired by polishing the bottom face 83 and the front and rear faces 84 and 85 as necessary.

  As mentioned above, although the typical Example of the grooving tool used by this invention was described, the grooving tool used by this invention is not necessarily specified only by the structure of said Example. For example, the angle of the cutting edge formed by the bottom surface and the front and back surfaces is preferably substantially perpendicular as described in the above embodiment, but may be formed to be somewhat obtuse.

Others The present invention can be appropriately modified and changed within the scope of achieving the object and without departing from the scope of the claims.

  INDUSTRIAL APPLICABILITY The present invention can be applied to a method for manufacturing an integrated thin film solar cell using a chalcopyrite compound semiconductor film, and a groove processing tool that can be used therefor.

W Solar cell substrate 7 Scribe head 8 Grooving tool 81 Body 82 Cutting edge region 83 Bottom surface of cutting edge region 84 Front surface of cutting edge region 85 Rear surface of cutting edge region 86 Cutting edge 87 Cutting edge 88 Side surface of cutting edge region 89 Side surface of cutting edge region

Claims (14)

(1) providing a solar cell substrate in which at least a lower electrode layer, a light absorption layer and an upper electrode layer are formed on an insulating substrate;
(2) Each of the regions that are divided from each other in the subsequent step of the solar cell substrate to become a functional region of each individual solar cell has a depth from the upper electrode layer side to the lower electrode layer surface, and is the same on the upper electrode layer surface. A patterning step of forming a plurality of grooves extending parallel to each other in the direction;
(3) Each layer extending in parallel with the plurality of grooves formed in the patterning step and extending from the upper electrode side to the lower electrode layer surface of the region located on both sides of the region serving as the functional region of the individual solar cell. Wide patterning process to remove and expose the lower electrode layer,
(4) A scribe process for forming a scribe line in a region where the lower electrode layer is exposed in the wide patterning process; and (5) a break process for breaking along the scribe line. Production method. The manufacturing method of the thin film solar cell of Claim 1 including the marking process of forming an alignment mark in the said solar cell board | substrate before the said patterning process. The method for manufacturing a thin film solar cell according to claim 2, wherein the alignment mark is formed by laser marking. An insulating process for performing an insulating process in a region perpendicular to the grooves on both ends of the plurality of grooves formed in the patterning process after the wide patterning process and before the scribe process or after the break process. The manufacturing method of the thin film solar cell of Claim 1 containing. The manufacturing method of the thin film solar cell of Claim 4 which performs the said insulation process by laser irradiation or mechanical scribing to an to-be-insulated part. The manufacturing method of the thin film solar cell of Claim 4 including the through-hole formation process of forming the through-hole which penetrates from the said upper electrode to the said board | substrate outside the area | region insulated after the said insulation process. The manufacturing method of the thin film solar cell of Claim 6 which uses a green laser processing apparatus for formation of the said through-hole. The method of manufacturing a thin film solar cell according to claim 1, wherein the solar cell substrate is a solar cell substrate in which a high-resistance buffer layer is formed between the light absorption layer and the upper electrode. The method for manufacturing a thin-film solar cell according to claim 8, wherein the solar cell substrate is a solar cell substrate in which an insulating layer is formed between the high-resistance buffer layer and the upper electrode. The light absorbing layer _{is, Cu (In, Ga) Se} 2, Cu (In, Ga) (Se, S) 2 and the thin film according to claim 1, wherein comprising a chalcopyrite compound selected from the group consisting of (CuInS ₂₎ A method for manufacturing a solar cell. The method for manufacturing a thin-film solar cell according to claim 1, wherein the lower electrode layer is a Mo layer. The method for manufacturing a thin-film solar cell according to claim 1, wherein the upper electrode layer is a transparent conductive film layer. The method for manufacturing a thin film solar cell according to claim 1, wherein the insulating substrate is a glass substrate. In the patterning step, the groove processing tool and the solar cell substrate are relatively moved in the groove forming direction while pressing the tip of a groove processing tool having at least a plate-like or rod-like tip against the groove forming portion on the upper surface of the upper electrode layer. The method for manufacturing a solar cell according to claim 1, wherein a groove extending from the upper electrode to the lower electrode surface is formed.