Adjusting the cleave angle of silicon wafers for solar cells
Patent Information
- Application Number
- EP2023736181
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-06-14
- Filing Date
- 2023-06-14
- Publication Date
- 2025-04-23
AI Technical Summary
Existing methods for cutting silicon wafers into solar sub-cells, such as laser-based techniques, often damage the edges and result in misorientation of the cleavage plane, leading to inefficiencies and difficulties in passivation, especially when separating closely spaced cells.
A method involving the creation of grooves on the silicon plate with a (100) crystal orientation upper face and (110) lateral edges, which guides a cleavage crack during mechanical separation, minimizing misorientation and facilitating clean cutting edges suitable for passivation, using abrasion instead of lasers to avoid edge damage.
This approach allows for precise cleavage with minimal edge damage and improved passivation, reducing yield loss and enhancing the manufacturing process by ensuring accurate orientation of the cleavage plane, thus improving the efficiency of solar cell production.
Smart Images
Figure 1.1
Abstract
Description
[0001] CORRECTION OF CLEAVAGE ANGLE OF SILICON WAFER
[0002] FOR SOLAR CELLS
[0003] DESCRIPTION
[0004] TECHNICAL FIELD
[0005] This application concerns the field of solar cells also called photovoltaic cells.
[0006] It applies in particular to solar cell devices resulting from the assembly of portions of crystalline silicon plates and more particularly aims at an improved method for enabling the division of a silicon plate and for producing a sub-solar cell or an assembly of sub-solar cells.
[0007] STATE OF THE PRIOR ART
[0008] A solar cell is usually formed on a plate, commonly called a "wafer", of semiconductor material, typically silicon.
[0009] For certain applications, it may be necessary to cut such a plate into several portions and create sub-cells, for example half-cells when the plate is divided in two.
[0010] A particular application concerns the implementation of a solar module structure according to an arrangement of the type called "shingle" presented for example in the document US2017 / 0077343°Al. In such an arrangement, sub-cells are superimposed so as to partially overlap each other. Such an assembly method called "shingling" or "shingle" arrangement makes it possible to reduce resistive losses and to obtain a power gain on the module.
[0011] Sub-cells are typically obtained by cutting a wafer on which their constituent elements have been at least partially produced and preferably once their constituent elements have been fully manufactured. Here, there is no need to modify an entire cell manufacturing line but only to carry out one or more additional steps, which presents a significant advantage in terms of manufacturing cost.
[0012] There are several methods for separation into sub-cells.
[0013] One approach involves generating a trench across the entire thickness of a silicon wafer using a laser to separate the sub-cells. This technique is efficient and precise, but has the major drawback of damaging the edges of the sub-cells near the cutting line. The laser energy tends to pulverize and locally melt the silicon.
[0014] Such damage may be accompanied by a possible loss of performance.
[0015] The subcell edges obtained with such a technique may further be difficult to passivate.
[0016] A second technique, also using a laser and a water-air cold source, involves generating a thermomechanical shock to create a separation crack. This second technique has the advantage of leaving a cleaner wafer surface and causes less yield loss than the previous technique.
[0017] A third technique is presented in document W02021111063 from the applicant.
[0018] It consists of using a different orientation of the lateral edges of the plate and the preferential cleavage plane of the silicon plate. This cleavage plane is oriented parallel to conductive lines commonly called "bus bars" (i.e. connection bars).
[0019] To achieve separation, mechanical stress is applied to propagate a separation crack, allowing the cell to split in two.
[0020] This technique has the advantage of generating a clean cut edge suitable for passivation. However, with such a technique, perfect orientation of the cleavage crack is difficult to achieve. In an ideal case, this orientation is perfectly parallel with opposite lateral edges of a plate on which the cell is made.
[0021] In reality, disorientation of the cleavage plane occurs frequently. However, too much disorientation can be detrimental, particularly when trying to separate very close cells or subcells.
[0022] There is therefore a need to find a new process to overcome this difficulty.
[0023] STATEMENT OF THE INVENTION
[0024] According to one embodiment, the present invention relates to a method for producing a photovoltaic device, comprising steps consisting of:
[0025] A) providing a silicon wafer provided with one or more solar cell(s) or solar sub-cell(s) manufactured at least partially, said wafer having a so-called "upper" face, a so-called "lower" face opposite the upper face, the upper and lower faces following a '(100)' crystal orientation, and lateral edges between said upper face and said lower face and following a '(110)' crystal orientation,
[0026] B) carry out on said upper face of the plate:
[0027] - a plurality of distinct grooves, said grooves being distributed on said upper face of the plate along a given axis A which extends parallel to first opposite lateral edges of said plate, or
[0028] - a single groove, which extends between second lateral edges orthogonal to the first lateral edges, the single groove advantageously joining the second lateral edges.
[0029] Such grooves allow a cleavage crack to be guided when it is later desired to mechanically cleave the plate. This allows a cleavage plane to be obtained with very little misorientation from the desired direction.
[0030] Advantageously, the plate is provided with at least one first conductive line and at least one second conductive line, the first and second conductive lines extending on the upper face of the plate parallel to said first lateral edges, the plurality of grooves or the single groove being produced between the first conductive line and said second conductive line.
[0031] Typically, after step B), a step of cleaving the plate by mechanical action on the plate is carried out by applying at least one force to it, in particular to bend the plate. During this cleavage step, a cleavage crack propagates between the grooves or along the single groove and the plate is separated into a first portion and a second portion. Each portion is capable of forming a solar sub-cell.
[0032] Advantageously, between step B) and step C): at least one starter notch can be formed in the plate at one of the second lateral edges.
[0033] After the wafer cleavage step: an assembly of the first portion with another portion of silicon or with said second portion can be implemented.
[0034] According to another aspect, an embodiment of the present invention provides a method for implementing a photovoltaic device, in particular at least one solar sub-cell comprising steps consisting of:
[0035] A) providing a silicon wafer provided with constituent elements of solar cell(s) or provided with at least partially produced solar sub-cell(s), said wafer having a so-called "upper" face, a so-called "lower" face opposite the upper face, the upper and lower faces following a '(100)' crystal orientation, lateral edges between said upper face and said lower face and following a '(110)' crystal orientation,
[0036] B) producing on said upper face of the plate: - at least a plurality of grooves distributed along a given axis which extends parallel to first opposite lateral edges of said plate, said grooves extending mainly respectively between second lateral edges opposite and orthogonal to said first lateral edges, or
[0037] - at least one groove along a given axis which extends between the second lateral edges, said at least one groove having a minimum length Lsmin between at least 50% and 80% of a measured distance Lt separating the second lateral edges, then, after step B), performing a step of cleaving the plate so as to form a cleavage crack propagating between the grooves or along said at least one groove and to perform a separation of the plate into a first portion and a second portion.
[0038] Advantageously, the step of cleaving the plate is carried out by mechanical action on the plate, in particular with bending by application of at least one force.
[0039] The method may comprise between step B) and step C): making at least one starter notch in said plate, said starter notch being formed at one of the second lateral edges.
[0040] Advantageously, said at least one plurality of grooves or said at least one groove is or are produced by abrasion of the upper face, in particular using one or more points.
[0041] According to one implementation possibility, the groove(s) is / are produced by abrasion using one or more abrasive elements such as points, for example diamond. Abrasion using an abrasive element rather than a laser advantageously makes it possible not to alter the cutting edges and to make it easier to passivate these edges revealed during cleavage of the plate.
[0042] Advantageously, at least a plurality of grooves or said at least one groove extends obliquely relative to the first lateral edges. Such a configuration makes it easier to intercept the cleavage crack. According to one possible implementation, the maximum distance L m ax between two successive grooves of said plurality of grooves or between on the one hand an end groove of said plurality of grooves closest to a second given edge among said second lateral edges and on the other hand this second given edge is:
[0043] (1) Lmax = Ds / Tan(ct*n / 180) with Ds a value of tolerated cleavage crack deviation chosen less than a distance separating two cells or two sub-cells formed on said plate, has a maximum tolerated misorientation angle of the predetermined cleavage crack less than 0.3° and preferably less than 0.1°.
[0044] The number of grooves of said at least one plurality of grooves between said second edges may be greater than N, with N = Lmax / Lt, Lt being the distance separating said second edges.
[0045] Advantageously, the grooves of said at least one plurality of grooves are arranged periodically according to a given distribution pitch.
[0046] According to one implementation possibility, the groove(s) has or have a width Ds of between 10 and 300 microns, preferably between 20 and 100 microns.
[0047] According to one implementation possibility, the groove(s) has or have a depth of between 1 and 20 microns, preferably between 1 and 10 microns.
[0048] According to one possible implementation, the method may further comprise, after the step of cleaving the plate: the assembly and / or interconnection of the first portion with another portion of silicon or with said second portion, so as to form a photovoltaic module or a string of interconnected sub-cells.
[0049] BRIEF DESCRIPTION OF THE DRAWINGS
[0050] The present invention will be better understood on the basis of the following description and the attached drawings in which:
[0051] Figures 1A and 1B are used to illustrate a structure formed from a silicon wafer intended to be cleaved by propagation of a cleavage crack and on which grooves are made to guide the propagation of this cleavage crack and prevent disorientation of the latter with respect to a desired direction.
[0052] Figure 2 is used to illustrate the creation of a succession of grooves made on the silicon plate to guide the cleavage crack.
[0053] Figure 3 serves to illustrate an example of a method of cleaving a silicon wafer on which grooves are made, the cleaving being carried out by bending the wafer.
[0054] Figure 4 is used to illustrate a division of a silicon wafer into distinct portions following a cleavage step.
[0055] Figure 5 serves to illustrate an assembly of portions of silicon wafer obtained by cleavage and then assembled in an arrangement of the type commonly called "shingle" or shingle.
[0056] [Figure 6 serves to illustrate the formation of at least one primer notch made on a plate (wafer) intended to accommodate at least one solar cell or solar sub-cell or at least one portion of a solar cell or solar sub-cell and intended to facilitate subsequent cutting of the plate into elementary portions.
[0057] Figure 7 serves to illustrate a possible disorientation of a cleavage plane of a silicon wafer with respect to a desired direction and which the creation of grooves on this wafer makes it possible to avoid.
[0058] Figure 8 serves to illustrate a possible dimensioning of the furrows.
[0059] Figure 9 is used to illustrate a cleavage of a plate on which bus bar type conductive lines have been formed.
[0060] Figure 10 serves as an alternative embodiment with a single guiding groove for a cleavage crack.
[0061] Figure 11 serves as an alternative embodiment of the grooves oriented obliquely relative to the lateral edges of the plate.
[0062] Figure 12 serves as an alternative embodiment of a cleavage crack guide groove extending from one edge of the plate. Identical, similar or equivalent parts of the different figures bear the same numerical references so as to facilitate the transition from one figure to another.
[0063] The different parts represented in the figures are not necessarily on a uniform scale, to make the figures more readable.
[0064] DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
[0065] A possible starting structure for implementing a method according to an embodiment of the present invention is given in Figures 1A and 1B. This structure is here formed from a silicon wafer 40 with opposite faces 41a, 41b called respectively "upper" and "lower" of crystallographic orientation '(100)', the wafer 40 comprising lateral edges 41c, 41d, 41e, 41f having a crystallographic orientation '(110)'.
[0066] The upper 41a and lower 41b faces typically have a rectangular or pseudo-rectangular shape and preferably a square or pseudo-square shape. By "pseudo-rectangular" is meant here that instead of a right angle joining two consecutive and orthogonal lateral edges 41c, 41d, there may be a curved portion (figure 1A), or a portion forming a bevel connecting these consecutive lateral edges 41c, 41d.
[0067] Such a plate 40 can be obtained using a method as described in document FR 3103965.
[0068] The plate 40 can thus be produced from an ingot which is cut so as to form a brick. This brick is provided with lateral sides having a crystallographic orientation '(110)' or substantially equal to the crystallographic orientation (110), and is then itself cut into several slices, the plate 40 being formed from one of these slices.
[0069] The aim is to cut this plate 40 by cleavage into several portions. These portions can each form a photovoltaic sub-cell. A photovoltaic sub-cell is a photovoltaic cell obtained from another larger photovoltaic cell or from a larger photovoltaic cell precursor. For example, it is possible to have sub-cells corresponding to half photovoltaic cells or quarter photovoltaic cells.
[0070] The plate 40 that one wishes to split may already comprise one, several, or all of the constituent elements of photovoltaic cells or sub-cells.
[0071] Thus, it is desired to carry out the cleavage while one or more technological steps for producing a solar cell or part of a solar cell have already been carried out on the plate 40. The solar cell(s) or sub-cell(s) produced may, for example, be of the heterojunction type (H ET).
[0072] Among these other technological steps may be one or more or all of the following steps:
[0073] - at least one surface texturing step,
[0074] - at least one doping step, in particular by diffusion of Boron, for example, on the lower and upper faces of the plate and / or by adding layers of amorphous Si doped on the surface,
[0075] - at least one etching step on the back face,
[0076] - at least one step of adding a barrier layer on the front face in order to prevent the addition of dopants during another diffusion step on the back face,
[0077] - at least one doping step on the rear face, in particular by diffusion of, for example, Phosphorus,
[0078] - optionally at least one etching of diffusion barrier layer(s) as well as layers created during the diffusion of phosphorus,
[0079] - at least one step of forming at least one passivation layer,
[0080] - at least one step of forming one or more anti-reflective layers.
[0081] In the case of HET cells or sub-cells, a barrier layer and barrier layer etching are not required. Amorphous Si / TCO (Transparent Conducting Oxide) layers are typically deposited on one side using a PECVD (Plasma-enhanced chemical vapor deposition) process.
[0082] In the illustrated embodiment, the plate 40 is provided on at least its upper face 41a with conductive lines 107, 109 commonly called bars or "busbars". The conductive lines 107, 109 are preferably arranged parallel to the lateral edges 41c, 41e of the plate 40.
[0083] Each conductive line 107, 109 makes it possible to conduct a photo-generated electric current following reception of photons on one or more sensitive areas of plate 40.
[0084] These conductive lines 107, 109 are typically metallic, for example based on Ag and can be formed for example by a screen printing or printing technique on the upper face 41a. Although not shown in FIGS. 1A, 1B, sets of metal grid fingers connected together by a conductive line 107, 109 can also be produced. These sets of conductive fingers placed opposite a sensitive area participate in the collection of the photo-generated current.
[0085] To facilitate the cleavage of the plate 40 into several portions, for example into at least two distinct elementary portions, a plurality of grooves 115 are formed as shown schematically in the partial top view of FIG. 2.
[0086] The grooves 115, also called “indentations” or “trenches”, are made by abrasion of the surface of the plate 40.
[0087] A device or tool, provided with one or more abrasive elements, such as tips, for example made of diamond, may in particular be used. The abrasion is preferably carried out here with an abrasive tool rather than with a laser, so as not to damage the material of the plate 40 and to subsequently allow the latter to be passivated more easily.
[0088] The grooves 115 are distributed on the upper face 41a between a first end 42A of plate 40 located at a lateral edge 41f and a second end 42B of the plate 40 located at an opposite lateral edge 41d of the plate 40, along a given axis A which is parallel to the upper face 41a and to opposite lateral edges 41c, 41e of the plate 40, orthogonal to the edges 41d, 41f.
[0089] The grooves 115 are here distributed along the given axis A between the conductive line 107 of a first solar cell or solar sub-cell C1 and the other conductive line 109 of a second solar cell or solar sub-cell C2 and extend between the first and the second end without intersecting the conductive lines 107, 109, preferably parallel to the conductive lines 107, 109.
[0090] Here, it is desired to cleave the plate 40 by propagation of a cleavage crack and preferably so that this cleavage crack does not, as illustrated in FIG. 7, encounter a cell or a sub-cell and in particular conductive lines 107, 109 when the crack deviates from the axis in which it is supposed to propagate.
[0091] The grooves 115 are provided here to prevent this untimely propagation. In the event of deviation of the cleavage crack mentioned above, the grooves 115 are provided to allow the trajectory of the cleavage crack Fc (shown schematically in Figure 2) to be deflected.
[0092] The grooves 115 can be provided with a length Is (dimension measured parallel to the x axis of an orthogonal reference frame [O; x; y; z] given in particular in FIG. 8) of, for example, between 500 microns and 2 mm, a width Ds of, for example, between 10 and 300 microns, preferably between 20 and 100 microns.
[0093] The depth of the grooves 115 (dimension measured parallel to the z axis, in other words orthogonal to the plane of figure 8) is preferably provided between one tenth of the total thickness e t of plate 40 and a third of the thickness e tof the plate 40. The grooves 115 may have a depth of, for example, between 1 and 20 microns, typically between 1 and 10 microns. The depth of the grooves 115 is preferably at most of the order of 1 / 10th of the thickness of the cell.
[0094] In the particular embodiment illustrated in Figure 2, the grooves 115 extend parallel or substantially parallel to the first conductive line 107 and to said second conductive line 109. The grooves 115 may be off-center with respect to a median axis (in the example corresponding to the axis A) of a separation zone between the cells or sub-cells C1, C2. According to a variant illustrated in Figure 11, the grooves 115 may advantageously be oriented at an angle with respect to the axis A, preferably between 0 and 45° with respect to this axis in order to better intercept the cleavage crack. A biased groove makes it possible to limit its width and to maximize the probability of collision between the cleavage crack and the groove.
[0095] A minimum number of grooves 115 is preferably provided in the cleavage zone between cells or subcells C1, C2.
[0096] Likewise, a maximum length Lmax is advantageously provided between two grooves 115 or between a groove 115 and a lateral edge 41d, 41f in order to be able to correctly produce the cleavage crack.
[0097] This maximum length Lmax can be planned so that:
[0098] Lmax = Ds / Tan(ct*n / 180), with Ds an authorized deviation value corresponding substantially to the width of the groove 115 chosen less than an inter-cell distance Wi2 Cl, C2 here less than the distance between the first conductive line 107 and the second conductive line 109 and typically less than half the distance between these conductive lines 107, 109, has a maximum tolerated cleavage crack misorientation angle relative to the predetermined axis A chosen less than 0.3°, preferably less than 0.1°. The deviation value Ds is typically between W12 / 6 and W12 / 2.
[0099] The number of grooves between the edges 41d, 41f is preferably provided to be greater than N, with N = Lmax / Lt, Lt being the distance between the edges 41d, 41f.
[0100] According to a particular embodiment, if we take for example a misorientation angle a of the order of 0.3°, a total cell length Lt = 156.75 mm (corresponding to the length of a solar cell of format commonly called “M2”, that we tolerate a deviation of 0.2 mm for a trench width of 0.6 mm, we provide N = 5 grooves 115, with a groove arranged according to a pitch Lmax of the order of 37 mm.
[0101] An example of carrying out a subsequent cleaving step aimed at dividing the plate 40 into several distinct and separate portions is illustrated schematically in FIG. 3. In this example, the plate 40 on which the grooves 115 are made is arranged on a cleaving support 130. A region of the lower face 41b (or upper face 41a) of the plate 40 is here supported on the support 130, while another region of this same face 41b (or 41a) is suspended, without being supported on this support 130 or on another support. A force F of a direction which makes a non-zero angle with the upper face 41a or lower face 41b of the plate 40, and preferably vertical (direction parallel to the axis z of an orthogonal reference frame [O; x; y; z]), is applied to a part of the plate 40. The plate 40 is thus put into bending and the application of this force F results in the propagation of a cleavage crack.The plate 40 is in this example suspended and is not supported on the support 130 or on another support, but other bending techniques can be used.
[0102] A separation between portions 40a and 40b of the plate 40 is thus implemented (figure 4). These portions 40a, 40b are typically provided to each form a portion of solar cell, in other words a sub-cell. In the illustrated embodiment, a cleavage into half-cells is carried out, but it is also possible to provide for dividing the plate 40 by cleavage into a number of portions greater than two, for example into six distinct portions.
[0103] In Figure 9, plate portions 40a, 40b separated by this cleavage technique each comprise at least one conductive line 107, 109, and a set of metal grid fingers 117, 119 connected to each other by a conductive line 107, 109. The fingers 117, 119 are typically oriented orthogonally to the conductive lines 117, 119.
[0104] Other ways of carrying out the cleavage than that shown in Figure 3 can be used, but here a purely mechanical method is preferred by imposing a bending on the plate 40, in order to be able to passivate the cutting edges 44a, 44b more easily.
[0105] The portions 40a, 40b are then intended to be assembled and / or interconnected to form a photovoltaic module.
[0106] In the case in particular, where the technological steps for producing a solar cell described above have already been carried out when the cleavage is carried out, the portions 40a, 40b obtained at the end of this cleavage can then be passivated at the level of the face or edge exposed by the cleavage and which is called the cutting edge 44a, 44b. Such passivation is typically carried out by depositing dielectric material such as for example Si N x or the AIO x deposited for example by PECVD. At least one of the portions 40a, 40b of plate obtained by cleavage can be directly assembled with another portion of plate in order to constitute an assembly of solar sub-cells.
[0107] In the particular embodiment of Figure 5, the portions 40a, 40b resulting from the cleavage of the plate 40 are then electrically assembled according to a particular “shingle” type arrangement, in other words where a portion 40a of the plate is in mechanical and electrical contact and overlaps another portion 40b. The other portion 40b can advantageously be connected to the portion 40a by means of a conductive adhesive 152.
[0108] To facilitate cleavage, it is possible, optionally, to produce, in addition to the grooves 115, at least one so-called “starter” notch 165, in other words a slot near or at an edge 41d or 41f of the plate 40. The notch thus forms a start of a cutting or separation zone on the plate intended to be completed later. This starter notch 165 can be provided for example with a length (dimension measured parallel to the x axis of the orthogonal reference [O; x; y; z] given in FIG. 6) of for example between 0.2 mm and 2 mm, advantageously between 0.5 mm and 1 mm. The starter notch 165 can be made with a depth (dimension measured parallel to the z axis) of, for example, between 30 μm and 60 μm for a plate with a total thickness e of between 130 μm and 160 μm. The starter notch 165 can be formed before or after the grooves 115 are made.
[0109] The notch 165 is here preferably also made with an abrasive element such as a point, for example made of diamond rather than with a laser. This also makes it easier to passivate an edge 41d of the plate 40 on which this notch 165 is formed.
[0110] In either of the embodiments just described, a succession of grooves 115 is made on the plate 40. Although it is preferably desired to minimize damage to the plate 40 and therefore the extent of the etched area, it is alternatively possible to provide a continuous groove 215 which extends from one edge 41d to an opposite edge 41f of the plate 40 or, as in FIG. 12, over at least a length Lsmin measured from an edge 41d or 41f of the plate 40.
[0111] In the case of a single groove, the length of the single groove is preferably provided to be at least a distance between an edge of the cell and the last groove furthest from this edge when forming a plurality of grooves according to the methods described above.
[0112] The minimum length of a single groove Lsmin is thus preferably provided between at least 50% and 80% of a distance Lt between the opposite lateral edges of the plate. For example, the length Lt for an M2 cell is of the order of 156.75mm.
[0113] In one or other of the embodiments which have just been described, a succession of grooves 115 or a continuous groove 215 is produced on a so-called “upper” face of the plate 40, between at least two portions of plates to be separated. This face, although called upper, does not necessarily correspond to the face commonly called the “front” face of a solar cell. Thus, a production of grooves on the rear face of a solar cell or of a solar cell during manufacture can also be implemented.
Claims
DEMANDS 1. A method for implementing a photovoltaic device, in particular at least one solar subcell, comprising steps consisting of: A) provide a silicon plate (40) having constituent elements of solar cell(s) (Cl, C2) or having at least partially realized solar sub-cell(s), said plate having a face (41a) called upper, a face (41b) called lower opposite to the upper face, the upper and lower faces following a crystalline orientation '(100)', lateral edges (41c, 41e) between said upper face and said lower face and following a crystalline orientation '(110)', B) to perform on said upper face (41a) of the plate (40): - at least a plurality of grooves (115) distributed along a given axis (A) which extends parallel to first opposite lateral edges (41c, 41e) of said plate (40), said grooves extending principally respectively between second lateral edges (41f, 41d) opposite and orthogonal to said first lateral edges, then, after step B), carry out a cleavage step of the plate so as to form a cleavage crack propagating between the grooves (115) and to effect a separation of the plate (40) into a first portion (40a) and a second portion (40b).
2. Method according to claim 1, said plate (40) having at least one first conductive line (108) and at least one second conductive line (109) extending over the upper face (41a) parallel to said lateral edges (41c, 41d), the grooves (115) being made between the first conductive line (107) and said second conductive line (109).
3. A method according to any one of claims 1 or 2, wherein the cleaving step of the plate is carried out by mechanical action on the plate (40), in particular by bending it by applying at least one force (F).
4. Method according to any one of claims 1 to 3, comprising between step B) and step C): making at least one primer notch (45) in said plate (40), said primer notch (45) being formed at one of the second lateral edges (41f, 41d).
5. A method according to any one of claims 1 to 4, wherein the grooves (115) are made by abrasion of the upper face (41a), in particular using one or more points.
6. A method according to any one of claims 1 to 5, wherein the grooves (115) extend obliquely with respect to the first lateral edges (41c, 41d).
7. A method according to any one of claims 1 to 6, wherein the maximum distance L max between two successive grooves of said plurality of grooves (115) or between on the one hand an end groove of said plurality of grooves (115) closest to a second given edge among said second lateral edges (41f, 41d) and on the other hand this second given edge is: (1) Lmax = Ds / Tan(ct*n / 180) with Ds a value of tolerated cleavage crack deviation chosen less than a distance separating two cells or two sub-cells formed on said plate, has a maximum tolerated cleavage crack misorientation angle of less than 0.3° and preferably less than 0.1°.
8. Method according to claim 7, wherein the number of grooves (115) of said at least a plurality of grooves (115) between said second edges (41f, 41d) is greater than N, with N = Lmax / Lt, Lt being the distance between said second edges.
9. A method according to any one of claims 1 to 8, wherein the grooves (115) are arranged periodically according to a given distribution step.
10. In a method according to any one of claims 1 to 9, the grooves (115) have a width (Ds) of between 10 and 300 microns, preferably between 20 and 100 microns.
11. In a method according to any one of claims 1 to 10, the grooves have a depth of between 1 and 20 microns, preferably between 1 and 10 microns.
12. A method according to any one of claims 1 to 11, further comprising after the cleaving step of the wafer (40): the assembly and / or interconnection of the first portion (40a) with another portion of silicon or with said second portion (40b), so as to form a photovoltaic module or a string of interconnected subcells.