WO2024110726A1

WO2024110726A1 - Metallization correction for pv cell cleavage

Info

Publication number: WO2024110726A1
Application number: PCT/FR2023/051828
Authority: WO
Inventors: Mickaël ALBARIC; Thibaut Desrues; Samuel Harrison; Benoît Martel
Original assignee: Commissariat A L'energie Atomique Et Aux Energies Alternatives
Priority date: 2022-11-22
Filing date: 2023-11-20
Publication date: 2024-05-30
Also published as: FR3142290A1

Abstract

The invention relates to a method for implementing a photovoltaic device, comprising: - measuring an angle θmes of misorientation of a given lateral side (41d) of a rectangular or square, crystalline silicon wafer with respect to a '(110)' crystal orientation, - forming, on the upper side, conductive tracks (55, 57, 59) that are oriented so as to make a given angle α to at least a first lateral side (41e) among said lateral sides, said angle being dependent on said measured misorientation angle θmes, then - performing a cleaving step so as to separate said wafer (40) into a first segment and a second segment.

Description

CORRECTION OF METALLIZATION FOR PV CELL CLEAVAGE

DESCRIPTION

TECHNICAL AREA

The present application concerns the field of solar cells also called photovoltaic cells and more precisely that of solar cells based on crystalline silicon.

It applies in particular to devices with solar cell(s) resulting from the assembly of portions of crystalline silicon plates and relates to an improved method for making it possible to divide a silicon plate and produce a solar sub-cell or an assembly of solar sub-cells, without altering the conductive track(s) arranged on the solar sub-cell(s).

STATE OF PRIOR ART

A solar cell is usually formed on a plate, commonly called a “wafer”, of semiconductor material, typically silicon.

We may, for certain applications, want to cut such a plate into several portions and produce sub-cells, for example half-cells (“half-cell” according to Anglo-Saxon terminology) when the plate is divided into two.

A particular application concerns the implementation of a solar module structure according to an arrangement of the type called “shingle” presented for example in document US2017/0077343°Al. In such an arrangement, the sub-cells are superimposed so as to partially overlap with each other. Such an assembly method called “shingling” or “shingle” arrangement makes it possible to reduce resistive losses and obtain a power gain on the module.

The 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 entirely manufactured. Here we do not 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.

There are several methods for subcell separation.

A technique is presented in document W02021111063 from the applicant. It consists of using a preferential cleavage plane of a crystalline silicon plate which corresponds to a direction parallel to the crystal orientation '(110)'.

To divide a plate, a mechanical stress is applied to propagate a separation crack making it possible to split the plate into two portions.

This technique has the advantage of generating a clean cutting edge conducive to passivation. However, with such a technique, perfect orientation of the cleavage crack may be difficult to achieve. In an ideal case, this orientation is perfectly parallel to opposite side faces of a plate on which the cell is made.

In reality, disorientation of the cleavage plane occurs frequently. However, too much disorientation can prove detrimental, in particular when one wishes to separate cells or sub-cells that are very close together. The separation is in fact typically carried out between the conductive tracks of two sub-cells that it is desired to separate.

These conductive tracks can be in the form of conductive lines commonly called “bus bars” (i.e. connection bars) and/or conductive fingers.

Thus, when we initiate a cleavage fracture we want the cleavage crack not to reach the conductive tracks formed on the cell that we wish to cleave. STATEMENT OF THE INVENTION

An aim of the present invention is to cleave a crystalline silicon plate provided with conductive tracks on an upper or lower face without altering these tracks.

Thus, for this, we implement steps including steps consisting of:

- measure on the crystalline silicon plate or on another crystalline silicon plate coming from the same brick of an ingot as said plate and/or from the same cutting process as said plate: a so-called “disorientation” angle 0 _m es of at least one given lateral face relative to a crystal orientation '(110)',

- form on said plate: one or more conductive tracks oriented so as to achieve an angle a given with respect to at least one first lateral face among said lateral faces and provided as a function of said angle 0 _m es of measured misorientation, then,

- carry out a cleavage step so as to separate said plate into a first portion and a second portion.

Advantageously, when the measured disorientation angle 0 _m es is greater than a first threshold 0 (min) and is less than a second threshold 0 (max), the conductive tracks formed are arranged relative to the first lateral face at an angle given a non-zero, equal to or less than the angle 0 _m es of measured disorientation.

When the measured misorientation angle 0 _m es is less than the first threshold 0 (min), it can be provided that the conductive tracks formed are arranged parallel to the first lateral face.

According to one possibility of implementing the method for which the cleavage is carried out by mechanical action while the angle 0 _m es of measured disorientation is greater than the second threshold 0(-max) but less than a third threshold S3, the method can further comprises, prior to cleavage, the production of one or more furrows distributed along a given axis in order to guide a cleavage crack, this given axis being determined as a function of the misorientation angle measured 0 _m es and arranged compared to the first lateral face at a given non-zero angle equal to or substantially equal to or less than the measured disorientation angle Qmes.

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.

According to an advantageous aspect, the cleavage method selected from several cleavage methods is selected as a function of the angle 0 _m es of disorientation measured.

Thus, advantageously,

- when said measured angle 0 _m es of disorientation is less than a threshold S3, typically 1°, the cleavage is carried out by mechanical action in particular by bending by applying at least one force on the plate or said other plate,

- when angle 0 _m es of disorientation is greater than the threshold S3, typically 1°, the cleavage is carried out by laser cutting.

According to one embodiment the conductive tracks can be formed:

- by screen printing using a screen mask equipped with one or more openings, the openings of the screen mask producing the non-zero angle a given with respect to the first side face.

According to a variant embodiment, the conductive tracks can be formed by producing an insulating mask comprising one or more holes arranged relative to said first lateral face of the plate so as to achieve the given angle a given non-zero and deposit of metallic material in the holes.

According to another alternative embodiment, the conductive tracks can be formed by deposition of a conductive material, in particular a conductive ink using a conductive material ejection element which is mobile and moves during deposition according to a trajectory achieving the non-zero angle a with respect to said first lateral face.

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

According to one possibility of implementing the method, the measurement of the disorientation angle 0mes can be carried out by:

- emission of a beam Ri of X-rays incident on said first lateral face of said plate and producing a non-zero angle

- identify the angular position of a detector De relative to the first lateral face for a maximum diffraction peak from the beam reflected by said first face.

According to another possible embodiment, the measurement of the angle 0 _m es of disorientation can comprise steps consisting of:

- carry out a step of cleaving said other plate,

- measure a first distance 11 between a first point of said given side face and a second point located on a side edge of said plate revealed at the end of said cleavage step,

- measure a second distance 12 between a third point arranged on said given side face and a fourth point of said side edge opposite said third point,

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

- deduce from the first, second and third distances, 11, 12, Dm2 a measurement of the angle between said slice and an axis parallel to said given lateral face.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood on the basis of the description which follows and the appended drawings in which:

Figures IA and IB illustrate a crystalline silicon plate intended to be cleaved and from which it is desired to evaluate a misorientation angle between a theoretical or desired cleavage plane and lateral faces of the plate. Figure 2 illustrates a first example of a method for measuring said disorientation angle using a goniometer.

Figure 3 illustrates an example of producing conductive tracks on the silicon plate whose orientation is planned as a function of a measured misorientation angle value.

Figure 4 illustrates an example of a method of cleaving the silicon plate carried out after formation of conductive tracks on the plate.

Figure 5 illustrates a step of cleaving the silicon wafer into distinct portions.

Figure 6 illustrates the production of a grid on the silicon plate formed of conductive tracks producing comb-shaped patterns, the tracks being oriented as a function of the measured misorientation angle value.

Figure 7 illustrates a second example of a method of measuring the angle of misorientation from another plate coming from the same cutting process as that from which the plate on which the conductive tracks are formed and then cleaved .

Figures 8A and 8B illustrate a cutting of silicon ingot into plates whose side faces are cut so as to come as close as possible to a '(110)' crystallographic orientation.

Figure 9 illustrates a zone between two conductive tracks in which it is desired to contain a possible deviation of the cleavage crack.

Figure 10 illustrates an alternative embodiment with a guide groove formed on the plate to allow the guidance of a crack during the cleavage of this plate.

Figure 11 illustrates an alternative embodiment with a succession of distinct guide grooves.

Figure 12 illustrates an alternative embodiment with a succession of guide grooves oriented at an angle relative to the conductive tracks.

Figure 13 illustrates a screen printing mask oriented according to the measured misorientation angle. Figure 14 illustrates an insulating masking perforated to allow metallization and which is oriented as a function of the measured misorientation angle.

Figure 15 illustrates doped regions whose orientation is predicted as a function of the measured misorientation angle.

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.

The different parts represented in the figures are not necessarily on a uniform scale, to make the figures more readable.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

A possible starting structure for the implementation of a method according to one embodiment of the present invention is given in Figures IA and IB.

This structure is here formed of a plate 40 of crystalline silicon with opposite faces 41a, 41b called respectively "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.

The plate 40 typically has a rectangular or square shape with opposite rectangular or square faces 41a, 41b. By "rectangular", we include here the shaped plates commonly called "pseudo-rectangular" having instead of a right angle joining two consecutive lateral faces 41c, 41d and orthogonal, a curved portion (figure IA), or a portion forming a bevel connecting these consecutive side faces 41c, 41d. Likewise, by "square", we include here plates of a shape commonly called "pseudo-square" with a bevel or a curved portion between two consecutive side faces.

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

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

A photovoltaic sub-cell SCI, SC2 is a photovoltaic cell obtained from another larger photovoltaic cell or from a larger photovoltaic cell precursor. We can for example have sub-cells corresponding to half photovoltaic cells, quarters of photovoltaic cells.

The side faces 41c, 41d, 41e, 41f normally have a crystallographic orientation '(110)', but here we wish to estimate a misorientation angle with respect to the crystallographic orientation '(110)' in order to estimate a possible disorientation d 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 angle of disorientation is generally between of the order of 0.05° to 0.2°, typically between 0.05° and 1°.

We thus measure, prior to a step of producing conductive tracks on the upper face 41a and/or lower 41b of the plate 40, an angle 0 _m es of at least one given lateral face 41c, 41d, 41e, 41f, of the plate 40 of crystalline silicon with respect to a crystal orientation '(110)'.

A method of measuring the crystal misorientation angle of the given side face 41c, 41d, 41e, 41f, of the plate 40 uses X-ray diffraction.

Figure 2 schematically illustrates an example of a measuring device making it possible to evaluate the angle 0 _m es of disorientation using an X-ray goniometer. The measuring device is provided with a source S0 which emits an X-ray beam Ri forming an angle with a given lateral face 41d on which the measurement is carried out. When the beam Ri meets the crystal lattice of this face 41d it is returned 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 carried out by this detector De we find the orientation of the mesh of face 41d.

The detector De is typically pre-positioned at an angle 0théo<no> = 23.65° relative to the measured lateral face. This position can be identified using a mechanical ball centering device (not shown). The angular value 0 _m retained corresponds to a measured value which is identified by a maximum diffraction peak and which corresponds to the angular disorientation relative to the orientation <110> for the measured lateral face.

To overcome a possible pre-positioning error 5 typically less than 0.2° and which mainly depends on the mechanical centering device, a second measurement can be carried out on the lateral face 41d, after rotation of the plate 40 by 180° by relative 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 reference frame [O;x;y;z] given in Figure 2.

A first measurement provides a value 501 = 0 _m es + 5. A second measurement is carried out after having rotated 180° of the same face 41d to then provide a measurement 502 = -0 _m es + 5. Angular disorientation 0 _m es is determined by applying a relationship: 0 _m es = (501 - 502)/2. The pre-positioning error 5 is determined by applying the relationship: 5= (501 + 502)/2

Depending on the value of the angle 0 _m es of disorientation determined, it may then be necessary to adapt the method of manufacturing solar cells or sub-cells used from this plate 40.

In particular, the orientation of the conductive tracks which is then produced on the upper face 41a and/or on the lower face 41b is adapted, as a function of the measured misorientation angle Qmes.

When we estimate the non-negligible measured disorientation, we can plan to have the conductive tracks 57, 59 (usually arranged parallel to the side faces 41c, 41e of the plate 40) here oriented as a function of the angle 0 _m es of disorientation previously determined.

In the exemplary embodiment illustrated in Figure 3, the conductive tracks 57, 59 are thus spaced from one another and parallel to each other and so as to extend on the plate 40 at an angle a non- zero relative to an axis A parallel to lateral faces 41e, 41c of this plate 40.

The conductive tracks 57, 59 may correspond to metallic lines, for example based on Ag, commonly called bus bars or “busbars”. Each conductive track 57, 59 is intended to conduct an electric current photo-generated following reception of photons on one or more sensitive areas of plate 40.

The angle a of the conductive tracks 57, 59 relative to the lateral faces 41c, 41e can be chosen equal to the angle of disorientation measured 0 _m es or less than the angle Qmes of disorientation measured previously.

In this way, it is possible to subsequently cleave the plate 40 by propagation of a cleavage crack intended 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 therefore does not possibly alter them.

The method of producing the conductive tracks 57, 59 is adapted to take into account the determined angle 0 _m es of disorientation. The conductive tracks 57, 59 can thus be formed, for example, by a screen printing or printing technique on the upper face 41a adapted specifically to implement tracks inclined at the angle a.

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

Thus, in the exemplary embodiment given in Figure 6, a conductive line 55 provided with an angle a relative to lateral faces 41e, 41c is connected to a set of conductive fingers 58 parallel to each other and spaced from each other . The fingers 58 can here make an angle, typically provided equal to ctwith the other side faces 41d, 41f of the plate 40.

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

In this example, the plate 40 is placed on a cleavage support 70 and a region of the lower face 41b (or upper 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 another support. A direction force F which creates a non-zero angle with the upper face 41a or lower 41b of the plate 40 and preferably vertical is then applied to a part of the plate 40 which is suspended and which is not resting on the support 60 or on another support. The application of the force F results in the propagation of a cleavage crack in a direction of crystallographic orientation '(110)'.

Other cleavage techniques by mechanical action can be provided. Thus, according to another embodiment not shown, the separation is carried out using a striker element which is brought into collision with an area of the plate 40.

As a variant of a cleavage process by purely mechanical action, it is also possible to implement another cleavage technique, in particular using a laser. Such a technique may be favored in particular when the measured disorientation angle Qmes is considered too large and greater than a threshold S3, for example 1°.

At the end of the cleavage (Figure 5) the portions 40a and 40b of the plate 40 separated from the plate 40 are obtained and designed to each form a half-solar cell. Then, the portions 40a, 40b of plate 40 obtained at the end of the cleavage can be passivated at the level of a lateral slice 45 exposed by the cleavage. Such passivation is typically carried out by deposition of a dielectric material such as for example SiN _x or _AIO At least one of the plate portions 40a, 40b obtained by cleavage can be directly assembled with another plate portion 40 in order to constitute an assembly of half-solar cells.

According to a variant embodiment of the method, it is possible to adopt a method of evaluating the angle of misorientation 0 _m es different from that described previously in connection with Figure 2.

Thus in another exemplary embodiment illustrated in Figure 7, the measurement of angle 0 _m es of disorientation is carried out directly from another plate 40' of crystalline silicon on which cleavage is carried out to obtain a portion 40'a of cleaved plate.

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

Such an ingot 4 and such a cutting are illustrated schematically in Figures 8A-8B. The plate 40 can be made from the ingot 4 which is cut so as to form a brick 14. This brick 14 is itself provided in the ideal case with lateral flanks having a crystallographic orientation '(110)' 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 41a (resp. 41'a) and lower 41b (resp. 41'b) faces of orientation crystallographic '(100)'.

The plates 40 and 40' resulting from the same cutting step have respective side faces with similar misorientations relative to the crystallographic orientation '(110)'.

From a portion 40'a obtained by cleavage of the plate 40', a first distance 11 is measured (dimension measured parallel to the y axis in Figure 7) between a first point Ml of a side 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.

We also measure a second distance 12 (dimension measured parallel to the first distance 11 and to the y axis in Figure 7) between a third point M3 arranged on the same side face 41'e and a fourth point M4 of said side edge 45' opposite said third point M3.

We also measure a distance Dm2 (dimension measured parallel to the x axis in Figure 7 and orthogonal to the first distance 11 as well as the second distance 12) between the first point Ml and the third point M3.

We then deduce from 11, 12 and Dm2 a measurement of the angle between said lateral edge 45 and an axis parallel to the direction '(110)'. Advantageously, the measurements can be produced from one or more digital images of the portion 40'a of cleaved plate.

The formula 0 _m es = 180/n*arctan[(l2-li)/Dm2] can then be used to deduce the disorientation.

In the example of the method described above, an orientation correction of the conductive tracks 57, 59 is carried out by providing conductive tracks 57, 59 making a non-zero angle α relative to the lateral faces 41e, 41c. However, this orientation correction can be considered optional in a case where the disorientation 0 _mes is less than a first determined threshold 0(min).

When the disorientation 0 _mes is sufficiently low not to risk reaching conductive tracks or metallization patterns during cleavage, we can in fact plan not to apply an orientation correction, that is to say to carry out the conductive tracks 57, 59 in a conventional manner, parallel to side faces 41e, 41c of the plate.

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

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 M12 format cell.

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

In the exemplary embodiment illustrated in Figure 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 » of a second sub-cell SC2 intended to be separated from the first sub-cell SCI after cleavage.

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 deviation maximum Dev_max (figure 9) tolerated is equal to Esc/2. The formula below expresses the deviation Dev as a function of a deviation angle P, and therefore allows us to know the angle from which Dev becomes greater than Esc/2.

Dev =l*tan(P*n/180) < Esc/2

For example, the spacing Esc between two sub-cells SCI, SC2 can be between 100 and 900 microns, for example 600 microns.

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

In the scenario as described previously in connection with 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, we avoid applying too much rotation compared to a conventional orientation of the tracks.

Indeed, when a rotation of metallization patterns is planned and these produce for example a grid pattern 60 as in FIG. 6, this grid pattern 60 could be incomplete if the orientation correction turns out to be too much. important.

Thus, we preferably choose an angle a for correcting the orientation of the metallization which is less than a second threshold 0(max).

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

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

0(max) = 180/ n*arctan(dbc/Lserig), with Lserig the total length (dimension measured parallel to the x axis in FIG. 6) of a conductive track 55 connected to the conductive fingers 58.

For example, for a 40 plate in M2 format and a distance dbc = 1mm, the second threshold 0(max) can be of the order of 0.4°. When the measured disorientation is such that 0 _m es > 0(max), but less than a third threshold S3, typically 1°, another correction measure can be provided to be able to carry out a cleavage without altering the conductive tracks.

A structure making it possible to deflect the cleavage crack and formed of one or more furrows 145 can in particular be provided.

Such a structure is shown schematically in the partial top view of Figures 10, 11, 12 and formed of one or more grooves.

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

The grooves 145 extend(s) 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 cutting the conductive tracks 57, 59.

In the example of Figures 11 and 12, the grooves 145 are parallel to the conductive tracks 57, 59.

The grooves 145 can be provided with a length Is 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.

In the particular embodiment illustrated in Figure 12, the grooves 145 intended to deflect the trajectory of a cleavage crack are this time oriented at an angle relative to the conductive tracks 57, 59.

We can define an angle Q = a-0(max) as a residual angle to be corrected by furrows 145. This residual angle can be taken into account here to calculate the minimum number N of furrows 145 to deflect a cleavage crack. A method of estimating this number of train paths N is given in French patent application No. 2205711 filed on June 14, 2022 before the National Institute of Industrial Property (INPI). For example, if we consider a plate format M2 of length = 156.75mm, an angle a of 1°, a second threshold 0(max)=O.5°, a residual angle of Q =0.5° and Dev_max of 300 microns, we can then plan to engrave 5 corrective furrows at a distance of approximately 35 mm from one furrow to the other.

In a critical case where the angle 0 _m es is large and greater than a third threshold S3, for example 1°, then we can plan to select a cleavage method different from the mechanical cleavage method mentioned previously.

In this case, to carry out the cleavage of cells without intervention on the metallization, one can opt for example for a separation method using a laser, in particular using a technique of thermal stimulation by laser (TLS) which does not depend on a preferential plane of cleavage and its orientation.

As described previously when it is planned to produce on the plate 40 of crystalline silicon conductive tracks 57, 59 producing a non-zero angle α with lateral faces 41e, 41c of this plate 40, the metallization process is adapted to obtain this corner.

For this, in the case where the tracks are produced by screen printing, a screen mask 110 can be used as shown in Figure 13 and provided with openings 112, 114 producing said non-zero angle α with respect to an axis itself. even parallel to the side faces 41e, 41c (not shown in Figure 13) of the plate 40.

Other methods of producing inclined conductive tracks can be provided.

According to another exemplary embodiment illustrated in Figure 14, a masking 120 of dielectric material is formed on the silicon plate provided with holes 122, 124 which extend in a direction achieving said non-zero angle a and less than S3 relative to FIG. to the side faces of the plate. The holes 122, 124 of the insulating mask can be made for example by laser engraving, the trajectory of which is adapted. The holes 122, 124 are then filled with conductive material to form the conductive tracks.

Thus, the principle of rotation of the pattern produced by the conductive tracks, in particular in the form of a metal grid, applies to different technologies of cells and in particular cells using metallization technologies other than screen printing.

As a variant, other metallization methods, for example of the inkjet printing type ("inkjet printing" according to Anglo-Saxon terminology) or electrochemical metallization ("electroplating" according to Anglo-Saxon terminology) can be used. used to produce the conductive tracks inclined relative to the edge of the cell.

In the particular 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 deposition according to a trajectory achieving the non-zero angle a given with respect to the lateral edges of the plate.

The rotation of angle a can also be applied to tracks or conductive elements made on the front face as well as on the rear face of the plate. It applies for example to PERC cells (for “Passivated Emitter and Rear Cell”).

The rotation of angle a can also be applied to other process steps, and in particular to doping or over-doping steps carried out upstream of the metallization.

Prior to producing the conductive tracks, it may be necessary to carry out doping of semiconductor regions 46, 48 of the plate 40, for example at its upper face. These semiconductor regions which may already be doped are then over-doped. Doping is for example carried out by implantation through a mask provided with openings revealing semiconductor regions 46, 48 which extend in a direction producing the non-zero angle a given with respect to lateral faces of the plate . The rotation of angle a applies to other doping techniques, in particular to laser-assisted doping or over-doping, or even to a diffusion technique using a mask.

A process as described above applies in particular to heterojunction solar cells. It can also be applied to other technologies of cells, for example to multi-junction cells, also called “tandem cells”.

Claims

1. Method for implementing a photovoltaic device, in particular at least one solar sub-cell (SCI, SC2) comprising steps consisting of:

- measure, on a rectangular or square crystalline silicon plate provided with an upper face (41a) and a lower face (41b) of crystalline orientation '(100)', or on another plate (40') of crystalline silicon from the same ingot brick as said plate (40) and/or from the same cutting process as said plate (40), a so-called “disorientation” angle 0 _m es of at least one lateral face given (41c, 41d, 41e, 41f) with respect to a crystal orientation '(110)',

- form on said upper face (41a) and/or on said lower face (41b) of said plate (40) one or more conductive tracks (57, 59), said conductive tracks being oriented so as to produce an angle a non- zero given with respect to at least one first lateral face (41e, 41c) among said lateral faces provided as a function of said angle 0 _m es of measured misorientation, then

- carry out a cleavage of said plate so as to separate said plate (40) into a first portion (40a) and a second portion (40b).

2. Method according to claim 1, in which, when said measured disorientation angle 0 _m es 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 relative to said first lateral face (41e, 41c) at a given angle a non-zero and equal to or less than said angle 0 _m es of measured misorientation.

3. Method according to one of claims 1 or 2, in which the cleavage is carried out by mechanical action by applying at least one force (F) on the plate (40) and in which, when said angle 0 _m is measured disorientation is greater than the second threshold 0(max) but less than a third threshold S3, the method further comprises, prior to cleavage by mechanical action, the production 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 misorientation angle measured 0 _m es and arranged relative to said first lateral face (41c, 41e) according to a given non-zero angle equal to or substantially equal to or less than said angle 0 _m es of measured disorientation.

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. Method according to one of claims 1 to 4, wherein the cleavage step is carried out according to a cleavage method selected from several cleavage methods as a function of said measured misorientation angle 0 _m es.

6. Method according to claim 5, in which:

- when said measured angle 0 _m es 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 angle 0 _m es of disorientation is greater than the third threshold S3, the cleavage is carried out by laser cutting.

7. Method according to one of claims 1 to 6, in which said one or more conductive tracks (57, 59) are formed:

- by screen printing using a screen mask (110) provided with one or more openings (112, 114), the openings of said screen mask achieving said non-zero angle a given with respect to said first side face (41 ^e , 41c) , Or

- by forming an insulating mask (120) comprising one or more holes (122, 124) said one or more holes being arranged relative to said first lateral face (41e) achieving said non-zero angle a given relative to said first face lateral (41 ^e , 41c) then by depositing a metallic material in said one or more holes, or - by deposition of a conductive material, in particular a conductive ink using an ejection element of movable conductive material, said ejection element moving during deposition along a trajectory achieving the angle a given no - zero with respect to said first side face (41 ^e , 41c).

8. Method according to one of claims 1 to 7, in which prior to the production of said one or more conductive tracks (57, 59), doping is carried out, in particular over-doping of regions (46, 48) semi -conductors of the plate (40) on which said conductive tracks are intended to be formed, said semiconductor regions (46, 48) being arranged so as to achieve the non-zero angle a given with respect to said first lateral face ( ^41e , 41c).

9. Method according to one of claims 1 to 8, in which the measurement of the angle 0 _m es of disorientation is carried out by emitting a beam (Ri) of X-rays incident on said first lateral face (41d) of said plate (40) and producing a non-zero angle and identifying the angular position of a detector (De) relative to the first lateral face (41d) for a maximum diffraction peak from the beam reflected (Rr) by said first face.

10. Method according to one of 1 to 8, in which the measurement of the angle 0 _m es of disorientation is carried out on said other plate and comprises steps consisting of:

- carry out a step of cleaving said other plate (40'),

- measure a first distance 11 between a first point (Ml) of said given side face and a second point (M2) located on a side 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 side face and a fourth point (M4) of said side edge opposite said third point (M3),

- evaluate a third distance Dm2 between the first point (Ml) and the third point (M3), - deduce from the first, second and third distances, 11, 12, Dm2 a measurement of the angle between said slice (45') and an axis parallel to said given lateral face.