DE102016210844A1 - Device and method for removing a layer - Google Patents

Abstract

The invention relates to a method for removing a layer of a layered body 1, in particular a CIGS solar cell, wherein the layered body 1 a particular transparent substrate layer 10, a preferably metallic and / or conductive first layer 11 adhering to the substrate layer 10 and one on the first Layer 11 having adhered preferably semiconducting second layer 12, wherein by means of a laser beam 9a absorbed by the first layer 11, the first layer 11 for reducing adhesion between the second layer 12 and the first layer 11 is treated, and another laser beam 9b with a higher fluence than the laser beam 9a removes a portion 21 of the first layer 11 from the substrate layer 10 and a part 22 of the second layer 12 from a remaining on the substrate layer 10 portion 23 of the first layer 11 detaches. Reliable stripping can thus be made possible. The invention also relates to a laminated body and a device for ablation.

Description

The invention relates to a method for removing a layer of a laminated body, in particular a CIGS solar cell, as well as a laminated body and a device for removing a layer of a laminated body.

In a CIGS solar cell, a coating of a glass substrate initially takes place in a planar manner with the conductive and semiconductive layers, the so-called stack. This laminar coating must be subsequently structured, ie removed or stratified layer-specifically.

To produce a CIGS solar module, usually all layers of the CIGS solar cell deposited on the substrate layer are stripped or exposed at the edge of the glass substrate, so that the substrate can be electrically insulated and laminated with moisture protection using a second glass.

Another application for the structuring of CIGS solar cells is the use for building glazing, where in certain areas of the solar cell of the solar module light is to fall through the solar cell to allow greater light into a room of the building.

The publication DE112010001893T5 discloses a solar cell module having a preferred edge space that prevents properties of a solar cell such as conversion efficiency from being destroyed without making the process complicated.

In the solar cell module comprising a glass substrate, a first layer formed on the glass substrate and a second layer formed on the first layer, the first layer is removed by a first removing means with a first amount of energy, thereby obtaining a first edge space, wherein the first layer is not is formed between an end part of the first layer and an end part of the glass substrate, and the second layer is removed by a second removing means with a second amount of energy, thereby obtaining a second edge space, wherein the second layer is not interposed between an end part of the second layer and the end part of the glass substrate is formed.

The teaching of the publication DE112010001893T5 provides for the use of a laser as an alternative to a sandblaster or a knife to remove the second layer from the first layer in a separate operation. This is time consuming and requires a lot of energy.

According to the document DE112010001893T5 For example, the width of the first edge space is 10 mm or more, and the width of the second edge space is 0.1 mm or more larger than the width of the first edge space. To lose as little power generating surface of a solar cell, however, would be advantageous if the width of the second edge space would be larger by less than 0.1 mm than the width of the first edge space.

The publication DE102012104230A1 discloses a method for introducing structure lines 21 in a thin-film photovoltaic module 2 , wherein the thin-film photovoltaic module 2 a transparent carrier substrate 22 has, which is provided on one side with a layer sequence, starting on the carrier substrate 22 an inner contact layer 23 , an outer contact layer terminating the layer sequence 25 and at least one photoelectric semiconductor layer disposed between these layers 24 comprises, in which at least one laser beam 31 that is on the thin-film photovoltaic module 2 directed and along desired structure lines 21 a selective layer removal of all layers of the layer sequence, except for the inner contact layer 23 over a width a and a selective layer removal of the inner contact layer 23 over a width b.

The width b is smaller than the width a, so that structure lines 21 with a graded depth arising within all layers of the layer sequence except the inner contact layer 23 a width a and within the inner contact layer 23 have a width b and between the resulting Abtragskanten the inner contact layer ( 23 ) and the resulting Abtragskanten all other layers of the layer sequence a distance c remains.

According to the teaching of the document DE102012104230A1 a removal of the photoelectric semiconductor layer takes place 24 from the inner contact layer 23 by evaporation. The resulting usually spatter of the material of the contact layer 23 stand against a use in the area of the P1-P3-Scribes. An ablation across the direction of the existing structuring is basically not possible without adverse effects on the subsequent solar cell. The same applies to the method according to the teaching of DE112010001893T5 ,

The abovementioned features known from the prior art can be combined individually or in any desired combination with one of the objects according to the invention described below.

It is an object of the invention to provide a further developed method in addition to device and product.

To solve the problem, a method according to the main claim and a device and a laminated body according to the independent claims. Advantageous embodiments will be apparent from the dependent claims.

To achieve the object, a method is used for removing a layer of a layered body, in particular a CIGS solar cell, where the layered body has a particularly transparent substrate layer, a preferably metallic and / or conductive first layer adhering to the substrate layer, and a semiconducting layer preferably on the first layer adhesion end second layer, wherein by means of a laser beam absorbed by the first layer the first layer for reducing adhesion between the second layer and the first layer is treated, and another laser beam having a higher fluence than the laser beam part of the first layer of removes the substrate layer and removes a portion of the second layer from a portion of the first layer remaining on the substrate layer.

Removing means peel off steam formation. A removed part is not usually completely evaporated, but is divided into flocks or particles with steam formation and propagated.

A detachment is a take-off or fly-away, which if necessary can separate a residual liability.

Substrate layer means substrate, ie in particular a base material that forms a bottom.

A laminated body is a multi-layered body.

A CIGS solar cell is a solar cell with a CIGS layer. In particular, a CIGS solar cell is divided into a plurality of cells by a plurality of longitudinal dividing grooves 2 divided.

Transparent substrate layer means a substrate layer transparent to the laser beam and / or further laser beam. In particular, the substrate layer is transparent to the part of the electromagnetic radiation visible to the human eye.

In particular, all layers of the layered body on the substrate layer may be transparent to the laser beam and / or further laser beam.

Sticking means a bond between two layers, between which acts an adhesion force. An adhesive layer may be coated, for example by coating such as e.g. be generated by sputtering.

A laser beam passing through the substrate layer traverses the substrate layer.

Reducing adhesion between the second layer and the first layer means that the particular areal force counteracting release of the second layer from the first layer is reduced.

Fluence is the radiant energy in J (Jule) per area (m ² ).

A laser beam and another laser beam may be separate by different beam sources or portions of a single laser beam from a single beam source.

A portion of the first layer removed from the substrate layer by the further laser beam may also be referred to as the first-layer removal portion. A portion of the first layer not removed from the substrate layer, i. remaining on the substrate layer may also be referred to as first-layer non-removal part. A first layer release part of the second layer may also be referred to as a second layer release part. A part of the second layer that does not detach from the first layer may also be referred to as a second non-layer release part.

In particular, a detached part is moved away from the layered body during detachment from the layered body and, in principle, does not remain loose, for example.

The fact that the adhesion between the second layer and the first layer is reduced by the laser beam, and that the further laser beam also removes a part of the second layer from the first layer when the first layer is removed from the substrate layer, can particularly reliably produce a marginal zone of the second layer which otherwise would or could be damaged by the heat input when removing the first layer from the substrate layer, which would reduce the performance of the laminate. A short-circuit-free production of exposed surfaces can thus be made possible.

Unlike the procedures of DE102012104230A1 and DE112010001893T5 The method according to the invention can also be used in a range of P1, P2 and P3 scribes, that is, those previously introduced into the layered body Verschaltungsbreiten and / or interstices in one or more layers by an ablative structuring of the one or more layers, are used.

The method according to the invention also makes it possible to ablate transversely to the direction of existing structuring (P1, P2, P3).

In particular, a laser ablation with a pulse length of 30ns as in the DE102012104230A1 Applicant's current knowledge in the P1-P3 regions normally leads to molybdenum spatters and thus short circuits in the later CIGS solar cell, since fewer layers are removed there than in the unstructured region of the cell.

In addition, by the treatment by a laser beam and the detachment of the second layer from the first layer by a further laser beam to remove the first layer, the energy consumption can be reduced.

The detachment of the part of the second layer from the part of the first layer remaining on the substrate layer by the method according to the invention for the reduction of the adhesion can be seen, in particular, from the fact that the surface of the first layer becomes visible in a planar manner and / or whether the part of the second layer remaining on the first layer after performing the process has a serrated edge contour, as in FIG 1a . 1b shown.

A toothed contour points between teeth lying on rounded incisions. The toothed contour is defined (dentate) in the field of foliage of plants.

A serrated outline looks like a series of "U" shapes or overlapping circles that cut out a border.

The complementary contour to the serrated contour is the notched contour (crenat), i. between the rounded projections (serrations) are acute cuts. In other words, the notched contour has round protrusions, with corresponding incisions tapering.

The detached part of the second layer from the part of the first layer which remains on the substrate layer basically has a notched contour correspondingly. A notched contour and a serrated contour fit together like two puzzle pieces.

By the treatment for reducing the adhesion between the first layer and the second layer, the surface of the first layer which has absorbed the laser beam can visibly darken or darken color than an inner region that is spaced from the edge termination region, rather than immediately Contact with the laser beam has come.

Alternatively or additionally, a streak-like surface structure of the first layer, on which the laser radiation was absorbed, can be seen, in particular through the transparent substrate layer, with the human eye, ie a surface with meandering structures, similar to a metal melted on for a short or short time.

The invention is based on the finding that, when removing the first layer from the substrate layer, it is necessary to use a further laser beam with such high energy or fluence that, in the case of a CIGS solar cell as a laminated body, in a marginal zone of the second layer as a CIGS layer as a result of the influence of heat the second layer no longer becomes semiconductive but becomes electrically conductive. This can cause short circuits in the later CIGS solar module and reduce the efficiency of the CIGS solar module. An ablation of the second layer can be achieved in a known manner with a laser beam with lower energy or fluence compared to the other laser beam, wherein no heat affected zone is formed, which would have a change in the semiconducting property of the second layer. By reducing the adhesion between the first layer and the second layer, peeling of the part of the second layer from the part of the first layer remaining on the substrate layer can be obtained by a mechanism which does not vaporize but rather entrains the detached part of the first layer second layer by removing the part of the first layer which is connected to the detached part of the second layer (see 7 ).

This different way of detachment, which is reflected in particular in the toothed contour, which usually results from the tearing out of flake-like parts of the second layer, and is not due to evaporation of the second layer, leads to reliable removal and energy saving , Above all, however, in this way it is also possible to ablate in the region of the P1 to P3 structures without impairing the layered body in such a way that short circuits occur in a later CIGS solar cell, for example.

The teachings of the pamphlets DE112010001893T5 and DE102012104230A1 see no treatment for reducing the adhesion between two layers, but describe only the known removal of the first layer and / or second layer by evaporation due to the laser energy, which usually only in unstructured solar cells, eg without P1-, P2, or P3-Scribes, or in principle only limited, eg only along the existing structuring, is possible, without obtaining a solar cell with increasingly occurring short circuits.

The features and embodiments described in connection with the following aspects of the invention, ie the laminated body and the device, also relate to the method according to the invention and can therefore be combined with the method. This concerns in particular the specifications and the structure of the laminated body.

Another aspect of the invention relates to a laminated body, in particular a CIGS solar cell, in particular produced according to an embodiment of the inventive method described above, wherein the laminated body a particular transparent substrate layer, adhering to the substrate layer preferably metallic and / or conductive first layer and on the first layer adhering preferably semiconducting second layer, wherein a step-like edge termination region of the first layer and the second layer has a serrated contour along the step-like edge termination region, and / or an edge region of a lower layer adhering to the substrate layer of the first layer, as distinguished from an interior region the lower surface has a visibly darker coloring and / or a schlieren-like surface structure.

In particular, the edge termination region and / or edge region can be transverse to a subdivision groove 2 between two cells extend as in 1b shown. In 1a the edge termination area and edge area run parallel to the subdivision furrow 2 ,

The features and embodiments described in connection with the method according to the invention also relate to the laminated body and can therefore be combined with this aspect of the invention.

At the step-like edge termination region, both the first layer and the second layer end, but not necessarily also the substrate layer.

The end of the first layer of the edge termination region is the edge region of the first layer.

The meaning of a toothed contour has already been explained in more detail above.

Along the step-like edge termination region means along the edge of the end of the first layer or steps of the step-like edge termination region, ie in particular parallel to the edge of the layered body, preferably parallel to the edge of the long side ( 1b ) or short side ( 1b ) of the laminated body. Along the step-like edge termination region means in the feed direction of the laser beam and / or the further laser beam.

Visibly darker coloration means that a noticeably darker coloration can be seen in particular through the transparent substrate layer with the human eye. In this case, interior area means a region which is at a distance from the edge termination area and has not come into direct contact with the laser beam.

Schlieren-like surface structure refers to a surface with meandering structures, similar to a metal melt that has been fused on for a short or a short time.

A solar cell with a particularly high efficiency and high quality can be obtained.

A further aspect of the invention relates to a device for removing a layer of a laminated body, in particular a CIGS solar cell, in particular for carrying out an embodiment of the method described above, comprising a laser source together with a device for laser beam splitting or alternatively two laser sources and a holder for fixing a Laminated body, in particular at least 2 microns and / or at most 5 microns thick.

The device is designed such that at least one laser beam and another laser beam are guided onto a fixed layered body and a relative movement in a feed direction between the layered body and the laser beam and / or the further laser beam can be generated, the at least one laser beam having a lower fluence as the further laser beam and is transversely to the feed direction - and / or in the feed direction - offset, wherein the offset is at least 40 microns and / or at most 60 microns and / or at least 20% preferably 50%, more preferably 80%, and / or at most 300%, preferably at most 120%, particularly preferably 100% a spot radius of the further laser beam on the laminated body.

Relative movement means that the layered body and / or the laser beam and / or the further laser beam are moved or are fixed in position.

At an offset greater than 100%, an intermediate region remains between the tracks of the laser beam 9a and the other laser beam 9b which does not reduce adhesion due to the laser beam 9a to the underlying first layer. Nevertheless, in the present case, this intermediate region is also referred to as "treated", because during the removal of the part 21 the first layer 11 the adhesion of the intermediate area is generally insufficient to the detachment of the part 22 the second layer 12 , which extends over the intermediate area to prevent. The part 22 the second layer 12 is thus replaced, even if it covers or includes an intermediate area without reduced liability.

The features and embodiments described in connection with the method according to the invention also relate to the device and can therefore be combined with this aspect of the invention.

In particular, the laser beam has at least 30% and / or at most 40% of the fluence of the further laser beam.

By means of the described device, a layer can be removed particularly reliably in a time-saving manner.

The invention will be explained in more detail with reference to embodiments schematically illustrated by drawings and with reference to the drawings, the embodiments and additional advantageous embodiments described in more detail.

It shows:

1a : Isometric view from above one out 3a enlarged portion of a laminated body in the form of a CIGS solar cell, which is cut in the plane AA, wherein the edge termination region extends parallel to the P1 to P3 structure lines.

1b : Isometric view from above one out 3b enlarged area of a laminated body in the form of a CIGS solar cell, wherein the edge termination region extends transversely to the P1 to P3 structure lines.

2 : Isometric view from below of one 3a enlarged portion of the laminated body, which is cut in the plane AA.

3a : Isometric view from above of a CIGS solar cell

3b : Isometric view from above of a CIGS solar cell with a continuous translucent area transverse to the subdivision furrow of the cells

4 : Schematic isometric view of a part of the first layer removed by the further laser beam and the part of the second layer detached therefrom with a section through the plane AA

5 : Schematic representation of a part of the first layer removed by the further laser beam and the part of the second layer detached therefrom in cross section

6 : Schematic representation of the beam profile of a Gaussian beam and the achievable removal of the first layer

7 : Schematic representation of a step-like removal of the first layer and detachment of the second layer on both sides of a removal of the first layer

8th : A device for laser beam splitting with feed direction in the viewing direction

9a : Another device for laser beam splitting in a view with feed direction transverse to the viewing direction

9b : The other device for laser beam splitting in a view with feed direction in the direction of view

10a : Microscopic image of a layered body in the form of a CIGS solar cell in plan view with serrated contour of the edge termination section

10b : Microscopic image of a further layered body in the form of a CIGS solar cell in plan view with a toothed contour of the edge termination section

In one embodiment, prior to treatment with the laser beam 9a and / or removal with the further laser beam 9b the first-layer removal part 21 adjacent to the first-layer non-removal part 23 adhered to the substrate layer 10 arranged and / or the second-layer release part 22 is adjacent to the second non-shift Transfer part 24 sticking on the first layer 11 arranged.

Adjacent means, in particular, contiguous and / or cohesively encompassed by the same layer, ie only geometrically adjacent areas. Side by side, adjacent and / or adjacent relate in particular to a cross-sectional plane, ie transversely to the feed direction 25 ,

A layer is basically held together by a cohesive force, which is oriented in the direction of the planar extent of the layer. An adhesion force is basically orthogonal to the cohesive force between layers arranged on top of each other.

In one embodiment, prior to treatment with the laser beam 9a and / or removal with the further laser beam 9b the second-layer release part 22 adhering to the first-layer non-removal part 23 arranged and / or the second-layer release part 22 covers the first-layer non-removal part 23 completely or at least predominantly or partially.

In one embodiment, treating the first layer 10 with the laser beam 9a the adhesion between the second-layer release part 22 and the first-layer non-removal part 23 reduced.

In one embodiment, treating the first-layer non-release part 23 the first layer 10 with the laser beam 9a the adhesion between the second-layer release part 22 and the first-layer non-removal part 23 reduced. In particular, by treating the first-layer non-release part 23 the second-layer release part 22 treated or treated as it were.

In one embodiment, removal of the first-layer removal portion 21 with the other laser beam 9b the treated second-layer release part 22 from the first-layer non-removal part 23 replaced.

In one embodiment, removal of the first-layer removal portion is accomplished 21 with the further laser beam 9b a flat area of the second layer 12 immediately above the first-layer-removal part 21 is adhesively disposed and / or the first-layer-removal part 21 completely or partially covered, as a coherent sub-layer composite removed and detached, wherein the second-layer release part 22 cohesively and / or by the cohesive force of the second layer 12 with this area of the second layer 12 and / or this sub-layer composite is firmly connected, so that by the reduced adhesion between the treated second-layer release part 22 and the first-layer non-removal part located thereunder 23 the second-layer release part 22 from the first-layer non-removal part 23 is detached and / or from the particular non-treated non-layer release part 24 that sticks on the first layer 11 is arranged, detached and / or demolished.

Treated second-layer release part 22 means that the first-layer non-removal part 23 from the laser beam 9a was treated. Treated non-layer release part 24 means that one of the non-shift part 24 covered area of the first layer 11 from the laser beam 9a was treated.

In one embodiment of the method breaks through the other laser beam 9b removed part 21 the first layer 11 the part 22 the second layer 12 both from the part 23 on the substrate layer 10 remaining first layer 11 as well as from the part 24 the remaining second layer 12 from and / or with and / or triggers this.

The part 22 the second layer 12 may be due to the reduced adhesion to the first layer 11 from the first layer 11 or the part 23 preferably be detached from it surface. The part 22 the second layer 12 then only from the part 24 the one on the first layer 11 remaining second layer 12 held. The kinetic energy of the removed part 21 the first layer 11 is greater than the cohesion of the second layer 12 thus failing by a tearing. In particular, the serrated contour is due to this tearing.

The surface 5 the substrate layer 10 , Where the part is 22 the second layer 12 is worn off, the surface is 5 no longer covered by a layer. In particular, a removal area extends 15 over the Abtragsbreite a and / or forms the beginning of a stepped edge portion range.

The removal area 15 closes in the stepped edge portion of the exposed portion 17 the surface 7 the first layer 11 at. The exposed portion forms a step of the step-shaped edge portion portion and / or has the step length b. In particular, the exposed section 17 exactly on the opposite side of the lower surface 6 and / or the border area 16 arranged and / or covers or overlaps this.

Finally, the contour forms 8th that are in particular orthogonal to the surface 7 the first layer extends upwards subsequent step shape of the step-shaped edge section area.

The tearing and / or entrainment causes the kinetic energy of the removed part 21 the first layer 11 used to ablate the second layer, while the treatment with the laser beam is used to determine the range of this ablation. Because if the adhesion between the first layer 11 and second layer 12 is not reduced, often no flat tearing or entrainment of the part 22 the second layer 12 from the remaining part 23 the first layer 11 respectively. The energy consumption can be reduced by utilizing the kinetic energy.

The removal of the part 21 the first layer 11 through the further laser beam 9a takes place with partial vapor formation of the first layer 11 so that you look at the process of removing the part 21 the first layer 11 like an explosion or blowing up under the second layer 12 can imagine.

Accordingly, the released kinetic energy is high. The movement of the removed part 21 including part 22 takes in the direction 26 as in 7 located. The 4 shows the parts blown away 21 . 22 , where in the true process the parts 21 . 22 not in the 4 shown manner, but also at least partially evaporated and destroyed in any case after removal and detachment and thrown away from the composite body.

In one embodiment, the laser beam 9 is reduced to reduce adhesion between the second layer 12 and the first layer 11 temporally before or simultaneously with the further laser beam 9b from the first layer 11 absorbed, in particular at the same cross-sectional position of the first layer 11 ,

Cross-sectional position means a plane transverse to a feed direction 25 of the laser beam 9a and / or the further laser beam 9b relative to the laminated body 1 , ie the feed direction 25 is the normal of the level (AA the 1 and 2 ).

As a result, the further laser beam 9b in a sense, the laser beam 9a or the laser beams 9a The cohesion of the later detached part can be traced 22 the second layer 12 enlarged and made the process so reliable.

As a result, the further laser beam 9b simultaneously with the laser beam 9a on the first layer 11 For generating a step-shaped Abtrages done, a time savings for the removal can be achieved.

In one embodiment, the laser beam 9a and / or the further laser beam 9b first of the substrate layer 10 transmitted and then from the first layer 11 absorbed.

The laser beam 9a and / or the further laser beam 9b So are through the substrate layer 10 led to the first shift 11 to reach. The laser beam 9a and / or the further laser beam 9b thus pass through the substrate layer 10 ,

A particularly precise removal and a particularly simple design of the device for the removal can be made possible.

In particular, the laser beam 9a and / or the further laser beam 9b such that the substrate layer 10 for the laser beam 9a and / or the further laser beam 9b is transparent.

Alternatively, the laser beam 9a and / or the further laser beam 9bso be such that the one, several or all layers on the substrate layer 10 for the laser beam 9a and / or the further laser beam 9b are transparent and the laser beam 9a and / or the further laser beam 9b from the first layer 11 is absorbed without the substrate layer 10 to cross. The laser beam 9a and / or the further laser beam 9b then pass through transmission through one, several or all layers on the substrate layer 10 to the first shift 11 ,

In particular, the laser beam 9a and / or the further laser beam 9b first of all layers of the composite 10 transmitted on the substrate layer, that is guided from the opposite side of the substrate layer on the laminated body, and then from the first layer 11 absorbed.

In one embodiment, one on the remaining part 23 the first layer 11 remaining part 24 the second layer 12 a serrated contour 8th on.

The toothed contour 8th causes a particularly clean separation surface of the second layer 12 , ie with very few or no unwanted particles or weak points, which can fail during subsequent processing or operation and can lead to undesirable particles.

In one embodiment, the laser beam 9a and / or the further laser beam 9b in a feed direction 25 relative to the laminated body 1 over the laminate 1 emotional.

In particular, the composite is thereby 1 and / or a laser optics for guiding the laser beam 9a and / or further laser beams 9b on the laminate 1 moved through the device. So either the laser beam stays 9a and / or further laser beam 9b fixed in position and / or the laminated body 1 fixed position.

Efficient removal can thus be made possible.

In one embodiment, a relative movement of the laser beam takes place 9a and / or the further laser beam 9b in a feed direction 25 relative to the laminated body 1 over the laminate 1 and / or the laser beam 9a meets at least 20%, preferably 50%, more preferably 80%, and / or at most 300%, preferably at most 120%, particularly preferably 100% of a spot radius of the further laser beam 9b transverse to the feed direction 25 offset on the composite body 1 ,

Relative movement means that the composite body 1 and / or the laser beam 9a and / or the further laser beam 9b be moved or are fixed in position.

Spot radius is the radius of the laser beam in the focal point. In particular, the spot diameter, ie beam diameter in focus, is determined in the Liu plot, preferably at 1 / e ² .

The spot diameter is twice the radius of the laser beam.

A particularly effective treatment for reducing the adhesion between the first layer 11 and the second layer 12 can be achieved this way.

Preferably, the offset is at least 40 microns and / or at most 60 microns, more preferably, the offset is about 55 microns.

In one embodiment, the laser beam 9a a fluence of at least 0.08J / cm ² , preferably 0.09 J / cm ² and / or at most 0.12J / cm ² , preferably 0.11 J / cm ² . Most preferably, the fluence of the laser beam 9a approximately or exactly 0.10J / cm ² .

A reliable removal can be made possible.

In one embodiment, the further laser beam 9b a fluence of at least 0.20J / cm ² , preferably 0.25J / cm ² , more preferably 0.28 / J / cm ² and / or at most 0.4J / cm ² , preferably 0.35J / cm ² , more preferably 0.32J / cm ² . Most preferably, the fluence of the laser beam 9a approximately or exactly 0.298 J / cm ² .

A reliable removal can be made possible.

In one embodiment, the laser beam 9a and / or the further laser beam 9b at least 40 kHz and / or at most 60 kHz as frequency, preferably approximately or exactly 50 kHz.

In one embodiment, the laser beam 9a and / or the further laser beam 9b at least 4 ps and / or at most 10 ps as pulse length, preferably exactly 7 ps.

In one embodiment, the laser beam 9a and / or the further laser beam 9b at most 1 ns as a pulse length in order to use a particularly inexpensive beam source can.

In one embodiment, the laser beam 9a and / or the further laser beam 9b at least 185 mm / s and / or at most 215 mm / s as feed rate.

In one embodiment, the spot radius, the frequency and / or the feed rate can be adjusted so that at least one, preferably two, more preferably five pulses of the laser beam 9a and / or the further laser beam 9b per point, and / or at most twenty pulses per point.

A point is a localized area of the first layers 11 , in particular with an extent approximately or exactly the extension of the spot diameter.

In one embodiment, the laser beam 9a and / or the further laser beam 9b at least 40 microns and / or at most 80 microns as a spot diameter.

In one embodiment, the laser beam 9a a pulse energy of at least 10.00 μJ and / or at most 13.00 μJ, preferably exactly or approximately 11.25 μJ.

In one embodiment, the further laser beam 9b a pulse energy of at least 30.00 μJ and / or at most 35 μJ, preferably exactly or approximately 33.75 μJ.

In one embodiment, the laser beam 9a a power of at least 0.50 W and / or at most 0.60 W, preferably exactly or approximately 0.56 W.

In one embodiment, the further laser beam 9b a power of at least 1.6 W and / or at most 1.8 W, preferably exactly or approximately 1.69 W.

In particular, a focal position of at least -10 mm, preferably -3.5 mm, particularly preferably -1.5 mm and / or at most 10 , preferably at most 3.5 mm, more preferably at most 1.5 mm and / or exactly or about 0 mm.

A focus position describes the removal of the beam focus relative to the layered body 1 or first layer 11 , in particular in the beam direction

A focus position <0 means that the focus seen in the beam direction in front of the layer body or the first layer 11 lies. A focus position> 0 means that the focus seen in the beam direction is inside or behind the layered body or inside or behind the first layer 11 lies.

In particular, in the case of the laser beam 9a and / or the further laser beam 9b provided a Gauss beam. But also a Top-Hat beam profile can be used.

In particular, the wavelength of the laser beam is 1064 nm and / or the beam source is an Nd: YAG laser, preferably Tru Micro 5250C. But also a wavelength of 532 nm can be provided in principle.

The parameter ranges described above can each reliably treat the first layer 11 with the laser beam 9a for reducing adhesion between the first layer 11 and the second layer 12 enable.

In one embodiment, the laser beam is 9a and the other laser beam 9b produced by division of a single laser beam and / or the laser beam 9a meets both on one side of the further laser beam 9b as well as on the opposite side of the further laser beam 9b on the laminate 1 on.

By generating the laser beam 9a and the other laser beam 9b By dividing a single laser beam can be removed particularly efficiently and with a device with only one laser source.

When the laser beam 9a both on one side of the further laser beam 9b as well as on the opposite side of the further laser beam 9b on the laminate 1 This means that two separate laser beams 9a with identical or approximately identical properties, in particular by the division of the single laser beam together with the other laser beam 9b were generated.

A stepped removal on both sides of a structure line can thus be made possible.

In one embodiment, the edge width c of the edge region 16 and / or step length b of the first layer 11 at least 5 microns, preferably 20 microns, and / or at most 150 microns, preferably at most 100 microns, more preferably at most 30 microns. With border width c of the border area 16 and / or step length b of the first layer 11 are expansions in the direction transverse to the feed direction 25 or across the edge of the end of the first layer 11 meant.

In one embodiment, a removal width a of the first layer 11 on the substrate layer 10 at least 10 microns, preferably 40 microns, more preferably 50 microns.

On a substrate edge, the removal width a can be between at least 0.1 mm and / or at most 30 mm, for which a run-off of a plurality of juxtaposed webs with the other laser beam 9b necessary is.

To create a translucent area 19 In particular, for BIPV (Building Integrated Photovoltaic), the Abtragsbreite a between at least 0.1 mm and / or at most 100 mm, for which a departure several juxtaposed webs with the other laser beam 9b necessary is. In particular, with a single web, a removal width a of at most 70 μm, preferably at most 60 μm, can be achieved.

In one embodiment, the further laser beam follows 9b in a feed direction 25 the laser beam 9a to. In particular, it is the laser beam 9a in the feed direction to the other laser beam 9b added.

The laser beam 9a So meets a cross-sectional position of the first layer 11 before the further laser beam 9b reached this cross-sectional position.

A particularly reliable removal can thus be made possible.

In one embodiment, the device comprises an optical element for beam profiling of a single laser beam 9 on, which is such that a main maximum and at least one secondary maxima, preferably exactly two secondary maxima, can be generated, wherein the further laser beam 9b corresponds to the main maximum and / or the laser beam 9a corresponds to the secondary maxima.

The 3a , b shows a laminated body, in particular a CIGS solar cell, preferably is a thin-film solar cell. The 1a illustrates the mode of operation of a CIGS solar cell, in which electrons in the direction of the arrow are set in motion by the solar radiation and pass through the layers of the solar cell.

On a substrate layer 10 a laminated body, as in 3a b), which may be a CIGS solar cell which is transparent to visible light and / or comprises or consists of glass, initially became a conductive first layer 11 preferably applied with or from molybdenum, preferably by sputtering.

In particular, the layer thickness of the first layer 11 , in particular with or from molybdenum, at least 0.3 μm and / or at most 0.4 μm.

On the first layer 11 is a second layer 12 , In particular, a semiconducting absorber for receiving a large part of the incident light, preferably Cu (In, Ga) Se ₂ , applied. This application is preferably carried out by simultaneous thermal evaporation of the elements and / or deposition of the metals (in particular Cu, In, Ga) by electroplating, sputter deposition or other processes with subsequent heating in a selenium atmosphere.

In particular, the second layer 12 a CIGS layer or comprises or consists of CIGS.

In particular, the layer thickness of the second layer 12 at least 1.5 microns and / or at most 2.5 microns.

The fourth shift 14 is a TCO layer (transparent conducting oxides) or a visible light transparent conductive oxide layer, preferably aluminum-zinc oxide (AZO), ie an n-doped zinc oxide (ZnO) layer which is heavily doped with aluminum (Al).

In particular, the fourth layer 14 at least 0.3 μm and / or at most 0.4 μm thick.

Between the second layer 12 and fourth layer 14 can a third layer 13 be provided as a buffer layer or barrier layer, in particular with or from cadmium sulfide (CdS) and undoped ZnO, which is preferably applied by sputtering. In the present case, sputtering is preferably carried out in a chemical bath (English: chemical bath deposition, CBD).

In particular, the third layer 13 at least 0.03 microns and / or at most 0.06 microns thick.

In particular, the third layer 13 still comprise one or more additional layers, such as TCO.

The first shift 11 , second layer 12 , third layer 13 and / or fourth layer 14 form in particular a so-called stack.

A CIGS solar cell is a solar cell with a CIGS layer. A solar module is a ready-to-use solar cell device that is ready to be mounted and generate power after assembly from sunlight.

For the production of a solar module or CIGS solar module, this laminar coating must be subsequently structured.

Structuring means a targeted stripping or exposing one or more layers of the layered body 1 ,

At the substrate edge 18 of the laminated body 1 all are on the substrate layer 10 applied layers of the composite body 1 removed, so that the substrate layer 10 can be electrically insulated with an additional glass plate and laminated moisture-proof.

If a solar cell is provided for a solar module for the occupancy of roof and / or facade surfaces of buildings with the solar modules, which are provided simultaneously for the entry of daylight, must be in translucent areas 19 All layers of the composite body above the substrate layer 10 that is, the first layer, 11 , second layer 12 , third layer 13 and fourth layer 14 to be removed.

Preferably, ablation takes place by means of laser radiation 9 to achieve a quick and accurate exposure of one, several or all layers. Ablation can always be done mechanically by a needle, a knife and / or sandblasting.

In particular, an optic forms the laser beam 9 to a spot with a defined spot diameter on a surface 6 ,

In particular, a scanner, preferably an xy scanner, serves to move the laser beam 9a and / or the further laser beam 9b in a feed direction 25 relative to or over the surface 6 and / or across.

Preferably, the surface is the lower surface 6 the first layer 11 on the substrate layer 10 liable.

A special feature of the CIGS semiconductor material is that it loses its semiconductive properties at temperatures above 500 ° C and becomes conductive. This limits the use of lasers for structuring. Because at one edge of the spot is usually a heat affected zone, where the material is indeed heated, but no longer removed (zone IV of 6 ).

After a certain heat input, the CIGS tilts to a certain extent and creates a conductive edge zone (part 22 ). Even when using a narrow beam profile, so-called top hat profiles as in the DE102012104230A1 described, or the use of ultrashort pulse lasers in the ps range, so pico-second range, according to own knowledge of the applicant, the conductive edge layer can be prevented. Such an electrically conductive edge zone can generate a short circuit and thus significantly reduce the efficiency of the solar cell.

In addition, the notifying party found that another condition could lead to such short circuits. Because the first layer 11 and the second layer 12 already pre-structured, the laser beam must 9 Also de-scale areas, so remove a layer that does not match the first layer 11 and the second layer 1 are coated. This leads to a different removal behavior, which can be reflected, for example, in mergers, inter alia.

To short circuits through conductive edge zones 22 To avoid and obtain a solar cell with high efficiency, it is convenient to the layers 11 . 12 . 13 . 14 above the substrate layer 10 in the area of the heat affected zone.

In one embodiment, it is provided to set a single laser beam, which in particular has a Gaussian beam profile, such that when the layers are removed from the substrate layer 10 a two-step edge is formed, in particular by blasting away an edge zone of the CIGS layer, ie the second layer 12 so that a short-circuit-free solar cell can be obtained.

However, the necessary process window is comparatively narrow, so that a part of the single laser beam 9 in a laser beam 9a for treating for reducing adhesion and another laser beam 9b For the removal of the first layer advantageously allows a more comfortable, Fehlerrobusteres, wider process window.

By dividing the single laser beam 9 in a laser beam 9a and another laser beam 9 Advantages are especially evident in the separate adjustability of the power levels.

This can be achieved by the beam by means of steel divider ( 8th . 9a and 9b ) in main steel, so the other laser beam 9b , and secondary beams, so the laser beams 9a , is split.

8th assumes a feed direction perpendicular to the image plane, wherein the two laser beams 9a right and left of the other laser beam 9b be guided by a single laser beam 9 through beam splitter 29 or beam splitter cube was divided twice and deflected.

In the in 8th The embodiment shown becomes the original single laser beam 9 first with a beam splitter 29 in the ratio 3: 2 in a 90 ° deflected laser beam 9b and an intermediate beam split and the intermediate beam is in turn by another beam splitter 29 in the ratio 50:50 in the further laser beam 9b , which is also deflected 90 °, and in an additional laser beam 9a split, which has a deflecting mirror 27 by 90 ° to another deflection mirror 27 and then again to another deflection mirror 27 again deflected by 90 °, so that finally all the laser beams 9a and the other laser beam 9b are aligned in parallel and / or the laser beam 9b in the middle of the laser beams 9a proceeds. In particular, all laser beams become 9a and the other laser beam 9b orthogonally guided on the composite body.

An advantageous alternative is in the 9a and 9b shown at the two deflecting mirrors 27 saved. The original single laser beam 9 is first using a beam splitter 29 in the ratio 3: 2 in a 90 ° deflected laser beam 9a and an intermediate beam split and the intermediate beam is in turn by another beam splitter 29 in the ratio 50:50 in the further laser beam 9b , which is also deposited 90 °, and in an additional laser beam 9a split, which has a deflecting mirror 27 is deposited by 90 °, so that finally all the laser beams 9a and the other laser beam 9b are aligned in parallel and / or the laser beam 9b in the middle of the laser beams 9a proceeds. By an opposite offset of the two lenses 28 the laser beams 9a become the laser beams 9a perpendicular to the feed direction 25 added. When going from the top through the substrate layer 10 would look made the laser beams 9a and the other laser beam 9b a triangle.

Another alternative is the use of a diffractive optical element (DOE), which forms a main maxima with two secondary maxima.

Preferably, an axicon or DOE can be inserted, which generates secondary maxima. As an alternative or in addition, the edge section area to be removed can be driven over separately, in particular with multiple power intensities, in particular several times.

Another embodiment is the combination of mechanical scibing with a needle with a laser process, wherein the needle is first the second layer 12 down to the first layer 11 exposes a laser and then the first layer 11 erodes.

This process can also be reversed by first removing the laser from the entire stack and then exposing the conductive CIGS to the next needle.

In layer processing with a Gaussian-shaped pulsed laser beam 9a the absorbing first layer reacts 11 , also called back contact or conductor, depends on the introduced fluence. If the fluence is chosen to be high enough, four regions always form, which may vary in intensity depending on the intensity distribution. These four areas are described below and in 6 shown schematically.

In the area I, ie in the middle of a laser profile, the intensity is highest. Here, the energy input is typically so large that in general the substrate layer during removal of the first layer 11 can be slightly scratched.

In area II, the light intensity exceeds the so-called ablation threshold. From this threshold, enough energy is absorbed to form a bond between the first layer 11 and the substrate layer 10 to blow up and the first layer 11 , in particular all overlying layers, to be completely stripped.

In area III, while enough energy per surface per time is introduced, around the first layer 11 from the substrate layer 10 remove. However, the resulting kinetic energy, ie kinetic energy, is too low to reach the first layer 11 completely tear off the substrate layer 10 ,

In region IV, the laser light is from the first layer 11 absorbed. However, the low intensity at the edge of the Gaussian beam is not sufficient to remove the first layer. The photon energy is converted into heat energy, which can then propagate within the layers. Heating may modify the second layer 12 cause it to become conductive and cause short circuits.

To a short-circuit-free dividing line or contour 8th or separating surface is removal of the excessively heated second layer 12 or CIGS layer advantageous.

When the adhesion force between the layers is low, the CIGS layer becomes from the fold-up first layer 11 replaced in area III and then entrained (see 7 ). So the second layer 12 or a part to be replaced 22 the second layer 12 however, entraining CIGS layer from region IV is a treatment for reducing the adhesion between the first layer 11 and the second layer 12 usually required to get a stable process with a workable process window.

Especially with strong adhesion between the first layer 11 and the second layer 12 additional energy must be introduced according to the invention to the second layer 12 , ie in particular the potentially leading CIGS, in area III and IV ablate. This can in principle be done directly and indirectly, ie as known from the prior art by mechanical removal of the CIGS with the aid of a knife or indirect by the inventive additional treatment by a weaker laser beam 9a ,

The 10a and 10b show two micrographs of a CIGS solar cell, in which with a Nd: YAG laser (Tru Micro 5250C) a Gaussian beam first as a laser beam 9a The treatment was configured as follows to reduce the adhesion between the first layer 11 and second layer 12 each by separately traversing in the longitudinal direction, ie vertically in 10a and 10b for the left and right margins section: frequency 50 kHz, power 32%, ie 0.56 W, pulse energy 11.25 μJ, fluence 0.1 J / cm ² , feed rate 200 mm / s, spot diameter 60μm, pulse length 7 ps ,

In a third and final track was laser beam with the same parameters with the parameters given below 9b configured to the part 21 the first layer 11 along with the part 22 the second layer: frequency 50 kHz, power 90%, ie 1.69 W, pulse energy 33.75 μJ, fluence 0.298 J / cm ² , feed rate 200 mm / s, spot diameter 60 μm, pulse length 7 ps.

The paths of the two laser beams 9a lay transversely to the feed direction by 55μm left and right offset to the path of the other laser beam 9b ,

Only difference between the 10a and 10b underlying parameters was that in the 10a a Focus position of -3.5 mm and at the 10b a focal position of 1.5 mm was set. In both 10a and 10b , especially at 10b , is the serrated shape of the contour 8th clearly.

According to an alternative aspect of the invention, a removal of the part 22 the second layer 12 before, during or after the removal of the part 21 the first layer 11 through the further laser beam 9b respectively. In particular, then the part 22 the second layer 12 ablated by a different laser beam (not shown), in particular evaporated, preferably with a fluence between that of the laser beam 9a and that of the further laser beam 9b , Alternatively, a mechanical removal of the part 22 the second layer 12 take place, in particular by means of a needle, preferably with a diameter of 170 μm, or a knife.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 112010001893 T5 [0005, 0007, 0008, 0011, 0031, 0044]
• DE 102012104230 A1 [0009, 0011, 0031, 0033, 0044, 0172]

Claims (15)

Method for removing a layer of a laminated body ( 1 ), in particular a CIGS solar cell, wherein the laminated body ( 1 ) a particularly transparent substrate layer ( 10 ), one on the substrate layer ( 10 ) adhering preferably metallic and / or conductive first layer ( 11 ) and one on the first layer ( 11 ) adhering preferably semiconducting second layer ( 12 ), with the aid of one of the first layer ( 11 ) absorbed laser beam ( 9a ) the first layer ( 11 ) for reducing adhesion between the second layer ( 12 ) and the first layer ( 11 ) and another laser beam ( 9b ) with a higher fluence than the laser beam ( 9a ) a part ( 21 ) of the first layer ( 11 ) from the substrate layer ( 10 ) and a part ( 22 ) of the second layer ( 12 ) from one on the substrate layer ( 10 ) remaining part ( 23 ) of the first layer ( 11 ) replaces. A method according to claim 1, characterized in that by the further laser beam ( 9b ) removed part ( 21 ) of the first layer ( 11 ) the part ( 22 ) of the second layer ( 12 ) both from the part ( 23 ) on the substrate layer ( 10 ) remaining first layer ( 11 ) as well as the part ( 24 ) of the remaining second layer ( 12 ) replaces, breaks off and / or entrains. Method according to one of the preceding claims, characterized in that the laser beam ( 9a ) for reducing adhesion between the second layer ( 12 ) and the first layer ( 11 ) temporally before or simultaneously with the further laser beam ( 9b ) from the first layer ( 11 ) is absorbed. Method according to one of the preceding claims, characterized in that the laser beam ( 9a ) and / or the further laser beam ( 9b ) first of the substrate layer ( 10 ) and then from the first layer ( 11 ) are absorbed. Method according to one of the preceding claims, characterized in that one on the remaining part ( 23 ) of the first layer ( 11 ) remaining part ( 24 ) of the second layer ( 12 ) a toothed contour ( 8th ) having. Method according to one of the preceding claims, characterized in that a relative movement of the laser beam ( 9a ) and / or the further laser beam ( 9b ) in a feed direction ( 25 ) relative to the laminated body ( 1 ) over the laminate ( 1 ) and / or the laser beam ( 9a ) by at least 20%, preferably 50%, particularly preferably 80%, and / or at most 300%, preferably at most 120%, particularly preferably 100% of a spot radius of the further laser beam ( 9b ) transverse to the feed direction ( 25 ) is placed on the layered body ( 1 ) meets. Method according to one of the preceding claims, characterized in that the laser beam ( 9a ) has a fluence of at least 0.08J / cm ² , preferably 0.09 J / cm ² , and / or at most 0.12J / cm ² , preferably 0.11J / cm ² . Method according to one of the preceding claims, characterized in that the further laser beam ( 9b ) has a fluence of at least 0.20 J / cm ² , preferably 0.25 J / cm ² , more preferably 0.28 / J / cm ² and / or at most 0.4 J / cm ² , preferably 0.35 J / cm ² , more preferably 0.32 J / cm ² . Method according to one of the preceding claims, characterized in that the laser beam ( 9a ) and / or the further laser beam ( 9b ) at least 40 kHz and / or at most 60 kHz as frequency, at least 4 ps and / or at most 10 ps as pulse length, at least 185 mm / s and / or at most 215 mm / s as feed rate, and / or at least 40 μm and / or have at most 80 microns as a spot diameter. Method according to one of the preceding claims, characterized in that the laser beam ( 9a ) and the further laser beam ( 9b ) has been produced by division of a single laser beam and / or that the laser beam ( 9a ) on one side of the further laser beam ( 9b ) as well as on the opposite side of the further laser beam ( 9b ) on the composite body ( 1 ). Laminated body ( 1 ), in particular a CIGS solar cell, in particular produced by the method according to one of the preceding claims, wherein the laminated body ( 1 ) a particularly transparent substrate layer ( 10 ), one on the substrate layer ( 10 ) adhering preferably metallic and / or conductive first layer ( 11 ) and one on the first layer ( 11 ) adhering preferably semiconducting second layer ( 12 ), characterized by a step-like edge termination region of the first layer ( 11 ) and the second layer ( 12 ), which has a toothed contour ( 8th ) along the step-like edge termination region, and / or an edge region ( 16 ) one at the substrate layer ( 10 ) adherent lower surface ( 6 ) of the first layer ( 11 ), which in contrast to an interior ( 20 ) of the lower surface ( 6 ) a visibly darker coloration ( 3 ) and / or a schlieren-like surface structure ( 4 ) having. Laminated body ( 1 ) according to the preceding claim, characterized in that an edge width (c) of the edge region ( 16 ) and / or a step length (b) of the first layer ( 11 ) at least 5 μm, preferably 20 μm, and / or at most 150 μm, preferably at most 100 .mu.m, particularly preferably at most 30 .mu.m. Laminated body ( 1 ) according to one of the two preceding claims, characterized in that a removal width (a) of the first layer ( 11 ) on the substrate layer ( 10 ) is at least 10 .mu.m, preferably 40 .mu.m, particularly preferably 50 .mu.m. Device for removing a layer of a laminated body ( 1 ), in particular a CIGS solar cell, in particular for carrying out the method according to one of the preceding claims, comprising a laser source together with a device for laser beam splitting or alternatively two laser sources and a holder for fixing a laminated body ( 1 ), characterized in that the device is such that at least one laser beam ( 9a ) and another laser beam ( 9b ) on a fixed composite body ( 1 ) and a relative movement in a feed direction ( 25 ) between the laminated body ( 1 ) and the laser beam ( 9a ) and / or the further laser beam ( 9b ), wherein the at least one laser beam ( 9a ) a lower fluence than the other laser beam ( 9b ) and transversely to the feed direction ( 25 ), wherein the offset is at least 40 microns and / or at most 60 microns and / or at least 20% preferably 50%, more preferably 80%, and / or at most 300%, preferably at most 120%, more preferably 100% of a spot radius the further laser beam ( 9b ) on the composite body ( 1 ) is. Device according to the preceding claim, characterized in that the further laser beam ( 9b ) in a feed direction ( 25 ) the laser beam ( 9a ) follows.

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