METALLICATION CORRECTION FOR PV CELL CLEGILING

Abstract

A method for implementing a photovoltaic device comprising: - measuring a misorientation angle θmes of a given lateral face (41d) of a rectangular or square crystalline silicon wafer with respect to a crystalline orientation '(110)', - forming conductive tracks (55, 57, 59) on the upper face, oriented to achieve a given angle α with respect to at least one first lateral face (41e) among said lateral faces, determined according to said measured misorientation angle θmes, then - performing a cleaving step to separate said wafer (40) into a first portion and a second portion. Figure for the abstract: 6.

Description

Title of the invention: CORRECTION OF METALLICATION FOR PV CELL CLEGINNING technical field

[0001] The present application relates to the field of solar cells, also called photovoltaic cells, and more specifically to that of crystalline silicon-based solar cells.

[0002] It applies in particular to solar cell(s) devices resulting from the assembly of portions of crystalline silicon plates and relates to an improved method for dividing a silicon plate and producing a solar subcell or an assembly of solar subcells, without altering the conductive track(s) arranged on the solar subcell(s). PREVIOUS STATE OF THE ART

[0003] A solar cell is usually formed on a plate, commonly called a "wafer", of semiconductor material, typically silicon.

[0004] For certain applications, it may be necessary to cut such a plate into several portions and create sub-cells, for example half-cells ("half-cell" according to Anglo-Saxon terminology) when the plate is divided in two.

[0005] A particular application concerns the implementation of a solar module structure according to a type of arrangement called "shingle," as shown, for example, in document US2017 / 0077343°A1. In such an arrangement, subcells are superimposed so as to partially overlap each other. This assembly method, called "shingling," reduces resistive losses and increases the power output of the module.

[0006] Subcells 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. This does not require modifying an entire cell manufacturing line, but only one or more additional steps, which offers a significant advantage in terms of manufacturing cost.

[0007] There are several methods for separation into sub-cells.

[0008] A technique is presented in document WO2021111063 from the manderesse. It consists of using a preferential cleavage plane of a crystalline silicon plate which corresponds to a direction parallel to the crystalline orientation '(110)'.

[0009] To perform the division of a plate, a mechanical stress is applied to propagate a separation crack allowing the plate to be split into two portions.

[0010] This technique has the advantage of generating a clean cutting edge that is suitable for passivation. However, with such a technique, achieving a perfect orientation of the cleavage crack can prove difficult. In an ideal case, this orientation is perfectly parallel to opposite lateral faces of a plate on which the cell is formed.

[0011] In reality, a misorientation of the cleavage plane occurs frequently. However, excessive misorientation can prove detrimental, particularly when the aim is to separate very closely spaced cells or subcells. The separation is typically carried out between the conductive tracks of the two subcells that one wishes to separate.

[0012] These conductive tracks can be in the form of conductive lines commonly called "bus bars" (i.e. connecting bars) and / or conductive fingers.

[0013] Thus, when initiating a cleavage fracture, it is desired that the cleavage crack does not reach the conductive tracks formed on the cell that one wishes to cleave. Description of the invention

[0014] An object of the present invention is to achieve cleavage of a crystalline silicon plate having conductive tracks on an upper or lower face without altering these tracks.

[0015] Thus, for this purpose, steps are implemented including steps consisting of:

[0016] - measuring on the crystalline silicon plate or on another silicon plate crystalline material from the same block of ingot as said plate and / or from the same cutting process as said plate: an angle called "disorientation" of at least one given lateral face with respect to a crystalline orientation '(110)',

[0017] - to form on said plate: one or more conductive tracks oriented so as to to achieve a given angle a with respect to at least one first lateral face among said lateral faces and predicted according to said angle 0 of measured disorientation, then,

[0018] - perform a cleaving step so as to achieve a separation of said plate into a first portion and a second portion.

[0019] Advantageously, when the measured disorientation angle 0mes is greater than a first threshold 0(min) and is less than a second threshold 0(max), the conductive tracks formed are arranged with respect to the first lateral face at a given non-zero angle a, equal to or less than the measured disorientation angle 0mes.

[0020] When the measured angle of disorientation is less than the first threshold 0(min), It can be predicted that the conductive tracks formed will be arranged parallel to the first lateral face.

[0021] According to one possible implementation of the process for which the cleavage is carried out by mechanical action while the measured disorientation angle 0mes is greater than the second threshold 0(-max) but less than a third threshold S3, the process may further include prior to cleavage, the creation of one or more grooves distributed along a given axis in order to guide a cleavage crack, this given axis being determined as a function of the measured disorientation angle 0mes and disposed with respect to the first lateral face at a given non-zero angle equal to or substantially equal to or less than the measured disorientation angle 0mes.

[0022] Advantageously, the given axis along which the grooves are distributed extends between a first conductive track and a second conductive track among the conductive tracks.

[0023] According to an advantageous aspect, the cleavage method selected from several cleavage methods is chosen based on the measured disorientation angle.

[0024] Thus, advantageously,

[0025] - when said measured angle of disorientation is less than a threshold S3, ty In the first stage of cleavage, the splitting is carried out by mechanical action, in particular by bending, by applying at least one force to the plate or said other plate.

[0026] - when the angle of disorientation is greater than the threshold S3, typically 1°, the The cleaving is carried out by laser cutting.

[0027] According to one embodiment, the conductive tracks can be formed:

[0028] - by screen printing using a screen mask having one or more openings, the openings in the screen mask making the angle a given non-zero with respect to the first lateral face.

[0029] According to an alternative embodiment, the conductive tracks can be formed by making an insulating mask having one or more holes arranged with respect to said first lateral face of the plate so as to make the given angle angle a given non-zero and depositing metallic material in the holes.

[0030] According to another embodiment, the conductive tracks can be formed by depositing a conductive material, in particular a conductive ink, using a conductive material ejection element which is mobile and moves during the deposition along a trajectory making the given non-zero angle α with respect to said first lateral face.

[0031] Advantageously, prior to the fabrication of the conductive tracks, doping, in particular over-doping, of semiconductor regions of the plate or of said other plate on which said conductive tracks are intended to be formed can be carried out by providing these doped semiconductor regions oriented according to the angle given non-zero with respect to said first lateral face.

[0032] According to one possible implementation of the method, the measurement of the angle 0mes of disorientation can be carried out by:

[0033] - emission of a Ri beam of X-rays incident on said first lateral face of said plate and making a non-zero angle

[0034] - identify the angular position of a detector De with respect to the first face lateral for a maximum diffraction peak from the beam reflected by said first face.

[0035] According to another possible embodiment, the measurement of the angle of disorientation may include steps consisting of:

[0036] - perform a cleaving step on said other plate,

[0037] - measure a first distance 11 between a first point of said lateral face given and a second point located on a lateral edge of said plate revealed at the end of said cleaving step,

[0038] - measure a second distance 12 between a third point arranged on said face given lateral slice and a fourth point of said lateral slice opposite said third point,

[0039] - evaluate a third distance Dm2 between the first point and the third point,

[0040] - deduce from the first, second and third distances, 11,12, Due a measure of the angle between said slice and an axis parallel to said given lateral face. Brief description of the drawings

[0041] The present invention will be better understood on the basis of the following description and the accompanying drawings in which:

[0042] [Fig.1A]

[0043] [Fig. IB] serve to illustrate a crystalline silicon plate intended to be cleaved and from which one wishes to evaluate an angle of disorientation between a theoretical or desired cleavage plane and lateral faces of the plate;

[0044] [Fig.2] serves to illustrate a first example of a method for measuring said angle of deso navigation using a goniometer;

[0045] [Fig.3] serves to illustrate an example of the realization of conductive tracks on the silicon plate whose orientation is planned according to a measured value of the angle of disorientation;

[0046] [Fig.4] serves to illustrate an example of a method for cleaving the silicon wafer created after the formation of conductive tracks on the plate;

[0047] [Fig.5] serves to illustrate a step of cleaving the silicon wafer into distinct portions;

[0048] [Fig.6] serves to illustrate the realization of a grid on the silicon wafer formed of conductive tracks forming comb-shaped patterns, the tracks being oriented according to the measured disorientation angle value;

[0049] [Fig.7] serves to illustrate a second example of a method for measuring the angle of disorientation from another plate produced by the same cutting process as the plate on which the conductive tracks are formed and then cleaved;

[0050] [Fig. 8 A]

[0051] [Fig.8B] serve to illustrate a cutting of silicon ingot into plates whose lateral faces are cut so as to approach as closely as possible a crystallographic orientation '(H0)'.

[0052] [Fig.9] serves to illustrate an area between two conductive tracks in which one wishes to contain any possible deviation of the cleavage crack;

[0053] [Fig. 10] serves to illustrate an alternative embodiment with a guide groove formed on the plate to allow the guidance of a crack during the cleaving of this plate;

[0054] [Fig. 11] serves to illustrate an alternative embodiment with a succession of grooves of separate guidance;

[0055] [Fig. 12] serves to illustrate an alternative embodiment with a succession of grooves of guides oriented at an angle relative to the conductive tracks;

[0056] [Fig. 13] is used to illustrate a silkscreen mask oriented according to the angle of measured disorientation;

[0057] [Fig. 14] is used to illustrate an openwork insulating mask to allow metallization and which is oriented according to the measured angle of disorientation;

[0058] [Fig. 15] serves to illustrate doped regions whose orientation is planned according to of the measured angle of disorientation;

[0059] 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.

[0060] The different parts represented in the figures are not necessarily shown on a uniform scale, in order to make the figures more legible.

[0061] DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

[0062] A possible starting structure for the implementation of a process according to an embodiment of the present invention is given in Figures IA and IB.

[0063] This structure is here formed of a crystalline silicon plate 40 with opposite faces 41a, 41b referred to respectively as "upper" and "lower" of crystallographic orientation '(100)', as well as lateral faces 41c, 41d, 41e, 41f which extend between the upper face 41a and the lower face 41b.

[0064] The plate 40 typically has a rectangular or square shape with opposite faces 41a, 41b that are rectangular or square. The term "rectangular" here includes plates of a shape commonly called "pseudo-rectangular" which have instead of a right angle joining two consecutive orthogonal lateral faces 41c, 41d, a curved portion ([Fig. 1A]), or a portion forming a bevel connecting these consecutive lateral faces 41c, 41d. Similarly, by "square," we include here plates of the shape commonly called "pseudo-square" with a bevel or a curved portion between two consecutive lateral faces.

[0065] Such a plate 40 can be obtained for example using a process as described in document FR 3103965 from the applicant.

[0066] We seek to cut this plate 40 by cleaving it into several portions, in particular by mechanical cleaving, for example by bending the plate 40. The portions obtained at the end of this cleaving can each form a photovoltaic sub-cell SCI, SC2.

[0067] A photovoltaic subcell SCI, SC2 is a photovoltaic cell obtained from another, larger photovoltaic cell or from a larger photovoltaic cell precursor. For example, subcells can correspond to half-photovoltaic cells or quarter-photovoltaic cells.

[0068] The lateral faces 41c, 41d, 41e, 41f normally have a crystallographic orientation '(HO)', but here we wish to estimate a disorientation angle with respect to the crystallographic orientation '(110)' in order to estimate a possible disorientation of a cleavage plane Pc when the plate 40 is divided into two portions by mechanical action on this plate 40. The absolute value of the disorientation angle is generally between 0.05° and 0.2°, typically between 0.05° and 1°.

[0069] Thus, prior to a step of making conductive tracks on the upper face 41a and / or lower face 41b of the plate 40, an angle 0mes of at least one given lateral face 41c, 41d, 41e, 41f, of the crystalline silicon plate 40 is measured with respect to a crystalline orientation '(110)'.

[0070] A method for measuring the crystalline disorientation angle of the given lateral face 41c, 41d, 41e, 4If, of the plate 40 uses X-ray diffraction.

[0071] Figure 2 schematically illustrates an example of a measuring device for evaluating the misorientation angle θ using an X-ray goniometer. The measuring device is equipped with a source S0 that emits an X-ray beam Ri at an angle to a given lateral face 41d on which the measurement is performed. When the beam Ri encounters the crystal lattice of this face 41d, it is reflected in directions determined according to the orientation of the crystal lattice. By measuring, using a detector De, the intensity of the diffracted rays Rr as a function of the angular path taken by this detector De, the orientation of the lattice of face 41d is determined.

[0072] The detector De is typically pre-positioned at a theoretical angle 0° <no>= 23.65° per relative to the measured lateral face. This position can be identified by means of a mechanical ball centering device (not shown).

[0073] The selected angular value 0mes corresponds to a measured value which is identified by a maximum diffraction peak and which corresponds to the angular disorientation with respect to the orientation <110> for the measured lateral face.

[0074] To compensate for a possible pre-positioning error ô typically less than 0.2° and which depends mainly on the mechanical centering device, a second measurement can be taken on the lateral face 41d, after rotating the plate 40 by 180° with respect to a normal axis n to the lateral face 41d. This normal axis n is parallel to the direction of the x-axis of an orthogonal frame [O; x; y; z] given on [Fig. 2].

[0075] A first measurement provides a value ô01 = 0mes + ô. A second measurement is taken after rotating the same face 41d by 180° to provide a measurement Ô02 = -0mes + ô. The angular misorientation 0mes is determined by applying the relation: 0mes = (ô01 - 002) / 2. The pre-positioning error ô is determined by applying the relation: ô = (Ô01 + 002) / 2

[0076] Depending on the value of the determined angle of disorientation 0mes, it may then be necessary to adapt the manufacturing process of solar cells or sub-cells implemented from this plate 40.

[0077] In particular, the orientation of conductive tracks which are then made on the upper face 41a and / or on the lower face 41b is adapted according to the measured angle of disorientation.

[0078] When the measured disorientation is considered non-negligible, it is possible to plan to have the conductive tracks 57, 59 (usually arranged parallel to the lateral faces 41c, 41e of the plate 40) here oriented according to the angle 0mes of disorientation determined previously.

[0079] In the embodiment illustrated in [Fig.3], the conductive tracks 57, 59 are thus spaced apart from each other and parallel to each other and so as to extend over the plate 40 by making a non-zero angle α with respect to an axis A parallel to lateral faces 41e, 41c of this plate 40.

[0080] The conductive tracks 57, 59 can correspond to metallic lines, for example made of Ag, commonly called bus bars or "busbar". Each conductive track 57, 59 is intended to conduct a photo-generated electric current following the reception of photons on one or more sensitive areas of plate 40.

[0081] The angle a of the conductive tracks 57, 59 with respect to the lateral faces 41c, 41e can be chosen to be equal to the measured disorientation angle 0mes or less than the previously measured disorientation angle 0mes.

[0082] In this way, a cleavage of plate 40 can subsequently be carried out by pro paging of a cleavage crack supposed to follow a cleavage plane Pc which passes here between the conductive tracks 57, 59, without this cleavage crack coming to meet the conductive tracks 57, 59 and consequently not possibly altering them.

[0083] The method for producing the conductive tracks 57, 59 is adapted to take into account the determined misorientation angle θ. The conductive tracks 57, 59 can thus, for example, be formed by a screen printing or printing technique on the upper surface 41a specifically adapted to implement tracks inclined at angle α.

[0084] Other conductive elements can also be provided with a disorientation relative to their conventional orientation.

[0085] Thus, in the embodiment shown in [Fig. 6], a conductive line 55, provided at an angle α with respect to lateral faces 41e, 41c, is connected to a set of parallel conducting fingers 58, spaced apart from each other. The fingers 58 can here form an angle, typically provided equal to α, with the other lateral faces 41d, 41f of the plate 40.

[0086] Once the conductive tracks have been formed, the cleavage can be carried out. An example of the implementation of a subsequent cleavage step aimed at dividing the plate 40 into several distinct and separate portions is given in [Fig.4].

[0087] In this example, the plate 40 is arranged on a cleavage support 70 and a region of the lower face 41b (or upper face 41a) of the plate 40 is supported on the support 70, while another region of this same face 41b (or 41a) is suspended, without being supported on this support 60 or on any other support.

[0088] A force F, directed at a non-zero angle with the upper face 41a or lower face 41b of the plate 40 and preferably vertical, is then applied to a portion of the plate 40 that is suspended and not supported by the support 60 or any other support. The application of the force F results in the propagation of a cleavage crack in a crystallographic orientation direction '(H0)'.

[0089] Other mechanical cleaving techniques may be provided. Thus, according to another embodiment not shown, the separation is carried out using a striking element which is brought into collision with an area of ​​the plate 40.

[0090] As an alternative to a purely mechanical cleavage process, another cleavage technique can also be implemented, in particular using a laser. Such a technique may be preferred, in particular, when the measured disorientation angle Omes is considered too large and exceeds a threshold S3, for example, 1°.

[0091] Following the cleavage ([Fig.5]) portions 40a and 40b of plate 40 separated from plate 40 are obtained and intended to each form a half solar cell. Next, the portions 40a, 40b of plate 40 obtained after cleavage can be passivated at a lateral edge 45 exposed by the cleavage. Such passivation is typically carried out by deposition of a dielectric material such as, for example, SiNx or AlOX, deposited, for example, by PECVD (Plasma-Enhanced Chemical Vapor Deposition). At least one of the plate portions 40a, 40b obtained by cleavage can be directly assembled with another plate portion 40 to form an assembly of solar half-cells.

[0092] According to an alternative embodiment of the process, a method for evaluating the disorientation angle 0mes can be adopted that differs from that described previously in connection with [Fig.2].

[0093] Thus in another embodiment illustrated in [Fig.7], the angle measurement of disorientation is carried out directly from another crystalline silicon plate 40' on which a cleavage is performed to obtain a portion 40'a of cleaved plate.

[0094] This other plate 40' is similar to plate 40 and advantageously produced from the same silicon ingot 4 and from the same cutting process as the ingot 4 from which plate 40 is produced.

[0095] Such an ingot 4 and such a cutting method are schematically illustrated in Figures 8A-8B. The plate 40 can be made from the ingot 4, which is cut to form a brick 14. This brick 14 is itself ideally provided with lateral faces having a crystallographic orientation '(H0)' or substantially equal to the crystallographic orientation '(110)'. The brick 14 is then itself cut into several slices, the plates 40, 40' each corresponding to a slice with upper faces 41a (resp. 41'a) and lower faces 41b (resp. 41'b) having a crystallographic orientation '(100)'.

[0096] The plates 40 and 40' resulting from the same cutting step have respective lateral faces with similar disorientations with respect to the crystallographic orientation '(110)'.

[0097] From a portion 40'a obtained by cleaving the plate 40', a first distance 11 (dimension measured parallel to the y-axis on the [Fig.7]) between a first point M1 of a lateral face 41'e and a second point M2 located on a lateral edge 45' of said plate 40' revealed at the end of said cleavage.

[0098] A second distance 12 (dimension measured parallel to the first distance 11 and to the y-axis on the [Fig.7]) is also measured between a third point M3 arranged on the same lateral face 41'e and a fourth point M4 of said lateral slice 45' opposite said third point M3.

[0099] A distance Dm2 is also measured (dimension measured parallel to the x-axis) on [Fig.7] and orthogonally to the first distance 11 as well as to the second distance 12) between the first point M1 and the third point M3.

[0100] A measurement of the angle between said lateral slice 45 and an axis parallel to the direction '(HO)' is then deduced from 11,12 and Dm2. Advantageously, the measurements can be carried out from one or more digital images of the portion 40'a of the cleaved plate.

[0101] The formula 0mes = 180 / ir*arctan[(l2-li) / Din2] can then be used to deduce the disorientation.

[0102] In the example of the method described above, an orientation correction of the conductive tracks 57, 59 is performed by providing conductive tracks 57, 59 making a non-zero angle α with respect to the lateral faces 41e, 41c. However, this orientation correction can be considered optional in a case where the misorientation 0mes is less than a first determined threshold 0(min).

[0103] When the misorientation 0mes is sufficiently small so as not to risk reaching conductive tracks or metallization patterns during cleaving, it is indeed possible to plan not to apply orientation correction, that is to say to make the conductive tracks 57, 59 in a conventional way, parallel to lateral faces 41e, 41c of the plate.

[0104] The first threshold 0(min) can depend on the length Lp (dimension measured parallel to the x axis of the orthogonal frame [O;x ;y ;z] given on [Fig.lA]) of the plate 40 and a spacing value Esc provided between two sub-cells.

[0105] The length Lp is for example 156.75 mm for an M2 format cell, 166 mm for an M6 format cell, 182 mm for an M10 type cell, 210 mm for an Ml2 format cell.

[0106] This Esc spacing can correspond for example to a distance separating the conductive fingers of a first sub-cell and a conductive track of the "bus bar" type of a second sub-cell.

[0107] In the embodiment illustrated in [Fig.9], this spacing Esc corresponds to a distance separating a first conductive track 57 of the "bus bar" type from a first sub-cell SCI and a second conductive track 59 of the "bus bar" type from a second sub-cell SC2 intended to be separated from the first sub-cell SCI after cleavage.

[0108] If we consider Esc as the free spacing between two sub-cells SCI, SC2 and the separation takes place at the center of this spacing, then the maximum tolerated deviation Dev_max ([Fig.9]) is equal to Esc / 2. The formula below expresses the deviation Dev as a function of a deviation angle [3], and thus allows us to know the angle from which Dev becomes greater than Esc / 2.

[0109] Dev =l*tan([3*ir / 18O) < Esc / 2

[0110] For example, the spacing Esc between two subcells SCI, SC2 can be between 100 and 900 microns, for example 600 microns.

[0111] The first threshold 0(min) can be for example 0.1° for a 40 plate of format M2 and can be for example 0.08° for a 40 plate of format M12.

[0112] In the case as described above in relation to figures 3 and 6 where the conductive tracks 55, 57, 59 are oriented to compensate for the disorientation and maintain the cleavage plane in the spacing zone between two sub-cells SCI, SC2, however, too large a rotation is avoided compared to a conventional orientation of the tracks.

[0113] Indeed, when a rotation of metallization patterns is planned and these, for example, produce a grid pattern 60 as in [Fig.6], this grid pattern 60 could be incomplete if the orientation correction proved to be too significant.

[0114] Thus, we preferentially choose an angle a for correction of the orientation of the metallization which is less than a second threshold 0(max).

[0115] The second threshold 0 (max) can be determined for example by taking into account a nominal distance dbc as shown in [Fig.6] (dimension measured parallel to the y-axis) between an end of conductive fingers 58 located near the edge of the plate 40 and the edge of this plate 40.

[0116] In this case, we can define, for example, the maximum angle 0(max) not to be exceeded from the relation:

[0117] 0(max) = 180 / ir*arctan(dbc / Lserig), with Lserig the total length (dimension measured parallel to the x-axis on the [Fig.6]) of a conductive track 55 connected to the conductive fingers 58.

[0118] For example, for a 40 plate in M2 format and a distance dbc = 1mm, the second threshold 0(max) can be on the order of 0.4°.

[0119] When the measured disorientation is such that 0mes > 0(max), but less than a third threshold S3, typically 1°, another correction measure can be provided to enable cleavage without altering the conductive tracks.

[0120] A structure allowing the cleavage crack to be deflected and formed of one or more grooves 145 may in particular be provided.

[0121] Such a structure is schematically represented in the partial top view of figures 10, 11, 12 and formed of one or more grooves.

[0122] The grooves 145 are made by abrasion of the lower or upper face of plate 40. In the illustrated example, the grooves 145 are advantageously formed on the upper face 41a of plate 40 after making the conductive tracks 57, 59.

[0123] The grooves 145 extend along a given axis A which is parallel to the upper face 41a of the plate 40 and passes between a conductive track 57 of a first sub-cell and a conductive track 59 of a second solar sub-cell without cut the conductive tracks 57, 59.

[0124] In the example of figures 11 and 12, the grooves 145 are parallel to the conductive tracks 57, 59.

[0125] The grooves 145 can be provided with a length 1s 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. The depth of the grooves 145 can be, for example, between 1 and 20 microns.

[0126] In the particular embodiment illustrated in [Fig.12], the grooves 145 provided to deflect the trajectory of a cleavage crack are this time oriented obliquely with respect to the conductive tracks 57, 59.

[0127] An angle Q = aO(max) can be defined as a residual angle to be corrected by grooves 145. This residual angle can be taken into account here to calculate the minimum number N of grooves 145 required to deflect a cleavage crack. A method for estimating this number of grooves N is given in French patent application no. 2205711 filed on June 14, 2022, with the French National Institute of Industrial Property (INPI).

[0128] For example, if we consider a plate format M2 of length = 156.75mm, an angle a of 1°, a second threshold 0(max)=0.5°, a residual angle of Q =0.5° and Dev_max of 300 microns, we can then plan to engrave 5 corrective grooves at a distance of about 35 mm from one groove to the other.

[0129] In a critical case where the angle 0mes is important and greater than a third threshold S3, for example of 1°, then it is possible to plan to select a cleavage method different from the mechanical cleavage method mentioned previously.

[0130] In this case, to achieve cell cleavage without intervention on the metallization, one can opt for example for a separation method using a laser, in particular using a thermal laser stimulation (TLS) technique which does not depend on a preferential cleavage plane and its orientation.

[0131] As described previously, when conducting tracks 57, 59 are planned to be made on the crystalline silicon plate 40, making a non-zero angle α with lateral faces 41e, 41c of this plate 40, the metallization process is adapted to obtain this angle.

[0132] For this purpose, in the case where the tracks are made by screen printing, a screen mask 110 can be used as shown in [Fig. 13] and having openings 112, 114 making said non-zero angle a given with respect to an axis itself parallel to the lateral faces 41e, 41c (not shown in [Fig. 13]) of the plate 40.

[0133] Other methods of making inclined conductive tracks may be provided.

[0134] According to another embodiment illustrated in [Fig. 14], a masking 120 of dielectric material having holes 122, 124 is formed on the silicon plate which extend in a direction forming the non-zero angle α less than S3 with respect to the lateral faces of the plate. The holes 122, 124 of the insulating masking can be made, for example, by laser engraving with an adapted path. The holes 122, 124 are then filled with conductive material to form the conductive tracks.

[0135] Thus, the principle of rotation of the pattern made by the conductive tracks, in particular in the form of a metallic grid, applies to different cell technologies and in particular to cells using other metallization technologies than screen printing.

[0136] As an alternative to other metallization methods, for example inkjet printing or electroplating, conductive tracks inclined relative to the edge of the cell can be used.

[0137] In particular the case of inkjet printing, the deposition of conductive material, in particular a conductive ink, is carried out by means of a conductive ink ejection element which is mobile and moves during the deposition along a trajectory making the non-zero given angle a with respect to the lateral edges of the plate.

[0138] The rotation angle can also be applied to conductive tracks or elements made on both the front and rear faces of the plate. It applies, for example, to PERC cells (for "Passivated Emitter and Rear Cell").

[0139] The rotation angle a can also be applied to other process steps, and in particular to doping or overdoping steps carried out upstream of metallization.

[0140] Prior to the fabrication of the conductive tracks, it may be necessary to dope semiconductor regions 46, 48 of the wafer 40, for example, on its upper surface. These semiconductor regions, which may already be doped, are then over-doped. The doping is, for example, carried out by implantation through a masking device having openings that expose semiconductor regions 46, 48 extending in a direction forming a non-zero angle α with respect to lateral faces of the wafer. The rotation by angle α applies to other doping techniques, in particular to laser-assisted doping or over-doping, or even to a diffusion technique using a mask.

[0141] A process such as the one described above applies in particular to heterojunction solar cells. It can also be applied to other cell technologies, for example to multijunction cells, also called "cells tandem.< / no>

Claims

Demands

1. A method for implementing a photovoltaic device, in particular at least one solar subcell (SCI, SC2), comprising steps of: - measuring, on a rectangular or square crystalline silicon wafer having an upper face (41a) and a lower face (41b) with crystalline orientation '(100)', or on another crystalline silicon wafer (40') from the same ingot block as said wafer (40) and / or from the same cutting process as said wafer (40), a so-called "disorientation" angle of at least one given lateral face (41c, 41d, 41e, 41i) with respect to a crystalline orientation '(110)', - forming on said upper face (41a) and / or on said lower face (41b) of said wafer (40) one or more conductive tracks (57, 59), said tracks conducting elements being oriented so as to make a given non-zero angle α with respect to at least one first lateral face (41e,41c) among the said lateral faces provided according to the said measured angle of disorientation, then - perform a cleavage of the said plate so as to separate the said plate (40) into a first portion (40a) and a second portion (40b).

2. A method according to claim 1, wherein, when said measured disorientation angle 0mes is greater than a first threshold 0(min) and is less than a second threshold 0(max), said one or more conductive tracks (57, 59) formed are arranged with respect to said first lateral face (41e, 41c) at a given non-zero angle a equal to or less than said measured disorientation angle 0mes.

3. A method according to any one of claims 1 or 2, wherein the cleavage is carried out by mechanical action by applying at least one force (F) on the plate (40) and wherein, when said measured misorientation angle 0mes is greater than the second threshold 0(max) but less than a third threshold S3, the method further comprises prior to the cleavage by mechanical action, the making of one or more grooves (145) distributed along a given axis (A) to guide a cleavage crack, said given axis (A) being determined as a function of said measured misorientation angle 0mes and disposed with respect to said first lateral face (41c, 41e) at a given non-zero angle equal to or substantially equal to or less than said measured misorientation angle 0mes.

4. Method according to claim 3, wherein said given axis (A) extends between a first conductive track (57) and a second conductive track (59) among said conductive tracks.

5. A method according to any one of claims 1 to 4, wherein the cleaving step is carried out according to a cleaving method selected from several cleaving methods as a function of said measured misorientation angle.

6. Method according to claim 5, wherein: - when said measured angle of disorientation is less than a third threshold S3, the cleavage is carried out by mechanical action in particular by bending by applying at least one force (F) on the plate (40), - when the angle of disorientation is greater than the third threshold S3, the cleavage is carried out by laser cutting.

7. A method according to any one of claims 1 to 6, wherein said one or more conductive tracks (57, 59) are formed: - by screen printing using a screen mask (110) having one or more openings (112, 114), the openings of said screen mask forming said non-zero angle α with respect to said first lateral face (41e, 41c), or - by forming an insulating mask (120) having one or more holes (122, 124), said one or more holes being arranged with respect to said first lateral face (41e) forming said non-zero angle α with respect to said first lateral face (41e, 41c) and then depositing a metallic material in said one or more holes, or - by depositing a conductive material, in particular a conductive ink using a movable conductive material ejection element,said ejection element moving during deposition along a trajectory making the given non-zero angle α with respect to said first lateral face (41e, 41c).

8. A method according to any one of claims 1 to 7, wherein prior to the formation of said one or more conductive tracks (57, 59), a doping is carried out, in particular an overdoping of semiconductive regions (46, 48) of the plate (40) on which said conductive tracks are intended to be formed, said semiconductive regions (46, 48) being arranged so as to achieve the non-zero given angle α with respect to said first lateral face (41e, 41c).

9. A method according to any one of claims 1 to 8, wherein the measurement of The angle of disorientation is achieved by emitting a beam (Ri) of X-rays incident on said first lateral face (41d) of said plate (40) and making a non-zero angle and identifying the angular position of a detector (De) with respect to the first lateral face (41d) for a maximum diffraction peak from the beam reflected (Rr) by said first face.

10. A method according to any one of 1 to 8, wherein the measurement of the angle of disorientation is carried out on said other plate and comprises steps consisting of: - perform a cleaving step on said other plate (40'), - measure a first distance 11 between a first point (M1) of said given lateral face and a second point (M2) located on a lateral edge (45') of said other plate (40') revealed at the end of said cleavage, - measure a second distance 12 between a third point (M3) arranged on said given lateral face and a fourth point (M4) on said lateral slice opposite said third point (M3), - evaluate a third distance DI 112 between the first point (M1) and the third point (M3), - deduce from the first, second and third distances, 11, 12, Dm2 a measure of the angle between said slice (45') and an axis parallel to said given lateral face.

Images