Method and apparatus for printing on substrates for producing solar cells

Abstract

A method 500 for printing on a substrate 102 for producing solar cells, the method comprising: printing 501 a wet pattern on the substrate 102; extracting 503 three-dimensional morphological data of the wet pattern 104′ in real time using an online profilometer 101; wherein the printing of the wet pattern on the substrate is controlled in real time at least in part based on previous three-dimensional morphological data obtained by extracting the three-dimensional morphological data.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to a method for printing on a substrate for producing solar cells, a method for optimizing material consumption during the production of solar cells, and an apparatus for printing on a substrate for producing solar cells. Background Art

[0002] Solar cells are photovoltaic devices that convert electromagnetic energy in the form of incident light into electrical energy.

[0003] Photons of light strike the semiconductor material (e.g., p-doped semiconductor material) of a solar cell and excite electrons in the semiconductor material. If the photons incident on the solar cell have sufficient energy, electron-hole pairs are generated within the solar cell, with the electrons crossing the energy band gap of the semiconductor material and reaching the conduction band energy level. The electrons can then flow toward the n-doped semiconductor material of the solar cell while remaining in the conduction band; toward a first metal contact forming the negative electrode of the solar cell, which is in contact with the n-doped semiconductor material. Similarly, the electron-holes can move through the p-doped semiconductor material toward a second metal contact forming the positive electrode of the solar cell, which is in contact with the p-doped semiconductor material.

[0004] The first and second metal contacts are on opposite surfaces of the solar cell, and when light strikes the solar cell, a DC potential difference is generated between the metal contacts. In a closed circuit, a DC current flows through the solar cell, acting as a generator, thereby converting light energy into electrical energy.

[0005] The first metal contact, forming the negative electrode in contact with the n-doped semiconductor material, is formed by a thin layer of conductive material that forms the fingers of the solar cell. The fingers only cover a portion of the surface to avoid blocking photons from entering the solar cell material and the semiconductor material of the solar cell. Multiple solar cells are typically connected in parallel and / or series to provide higher current and / or voltage.

[0006] A busbar is a rod of conductive material connected to one or more fingers of a solar cell and is designed to collect current from the one or more fingers and direct the current to a circuit coupled to a load that receives the electrical energy generated by the solar cell.

[0007] Thus, the fingers are thin metal conductors that collect the generated DC current, delivering it to a bus bar that delivers the current to the load.

[0008] The busbars and fingers are printed on the surface of the semiconductor material of the solar cell using screen printing and are made of a high conductivity material such as, for example, silver paste.

[0009] In order to measure the amount of paste applied to the substrate of the solar cell, double weighing is usually performed before and after the printing process.

[0010] Optimizing slurry laydown is beneficial. Summary of the Invention

[0011] According to one aspect, the present disclosure provides a method for printing on a substrate for producing solar cells, the method comprising:

[0012] printing a wet pattern on the substrate;

[0013] extracting three-dimensional morphological data of the wet pattern in real time using an in-line profilometer;

[0014] Wherein printing of the wet pattern on the substrate is controlled in real time based at least in part on previous three-dimensional topology data obtained by extracting the three-dimensional topology data.

[0015] According to another aspect, the present disclosure provides a method for optimizing material consumption during production of solar cells, the method comprising:

[0016] Printing on a substrate 102 for producing the solar cell;

[0017] determining material consumption based on the extracted three-dimensional morphological data;

[0018] optimizing said material consumption;

[0019] The material consumption is the consumption of the material used to print the wet pattern on the substrate.

[0020] According to another aspect, the present disclosure provides an apparatus for printing on a substrate for producing solar cells, the apparatus comprising:

[0021] substrate holder;

[0022] Online profilometer;

[0023] an actuator coupled to the substrate holder;

[0024] a printer for applying a wet pattern on the substrate;

[0025] a controller coupled to the inline profilometer and the actuator and the printer and configured to control printing of the wet pattern on the substrate;

[0026] The online profilometer is configured to extract three-dimensional morphological data of the wet pattern on the substrate placed on the substrate holder in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Details related to implementations of the methods and apparatus of the present disclosure are shown.

[0028] Figure 2 Details related to implementations of the methods and apparatus of the present disclosure are shown.

[0029] Figure 3 Details of an embodiment of the method of the present disclosure are shown

[0030] Figure 4 An embodiment of a solar cell related to the present disclosure is shown

[0031] Figure 5 A method of printing on a substrate for producing solar cells according to the present disclosure is shown.

[0032] Figure 6 The height of the printed wet patterns for different wafers is shown.

[0033] Figure 7 The height of the printed wet patterns for different wafers is shown.

[0034] Figure 8 Shown are the heights of printed wet patterns for different wafers provided by the present disclosure.

[0035] Figure 9 Examples of the height of printed wet patterns obtained using prior art methods are shown.

[0036] Figure 10 Shown are examples of the height of printed wet patterns obtained according to embodiments of the present disclosure.

[0037] Figure 11 Shown are examples of the height of printed wet patterns obtained according to embodiments of the present disclosure. DETAILED DESCRIPTION

[0038] The present disclosure provides methods and systems involving laser systems for in-line, real-time 3D scanning of printed fingers and busbars.

[0039] This application extracts 3D morphological data of wet-printed fingers and busbars in real time. This data can be used to improve real-time control of the printing process.

[0040] Monitoring of slurry deposition is an important indicator of cell efficiency in the production of solar cells.

[0041] The present disclosure allows overcoming the limitations of manual measurements of slurry deposition that are performed off-line at the expense of operator time, and also allows overcoming the limitations of automatic measurements that can only be performed at a low frequency, for example based on double weighing.

[0042] Some embodiments of the present disclosure can use measurements of a portion of the 3D finger morphology of each printed cell to assess slurry deposition. Thus, deviations can be monitored in real time throughout production, providing process control with improved accuracy.

[0043] Traditionally, control of slurry deposition during production is accomplished through sampling, either manually by an operator or by an in-line scale that operates automatically at a low frequency.

[0044]

[0014] Embodiments of the present disclosure relate to using metrology to indirectly estimate the laydown of a wet slurry, such as by using a 3D laser profilometer.

[0045] The present disclosure makes it possible to monitor the entire production and achieve real-time process control. The present application improves production efficiency by eliminating the offline double weighing of batteries before and after printing that is manually completed by operators (for example, once every 4 hours), and improves system yield through real-time feedback.

[0046] The present application may be suitable for integration with Industry 4.0, thereby increasing the synergy of data processing.

[0047] A system according to the present disclosure may include a multi-head 3D laser and a controller coupled to a processing line (eg, via Ethernet).

[0048] While the 3D laser head remains fixed, the wafer to be measured can be moved under the 3D profiler and the printed layout is scanned in the forward direction.

[0049] In addition to evaluating slurry deposition, 3D laser profilometers can also be used to monitor finger and busbar morphology, thereby preventing loss of print quality and soldering issues on the busbars.

[0050] The measured print volume can be used to calculate the slurry deposition by a dedicated algorithm.

[0051] Figure 1 Details related to implementations of the methods and apparatus of the present disclosure are shown.

[0052] Conductive paste 104 is placed on top of substrate 102, which is placed on substrate holder 120. Conductive paste 104 may be applied to substrate 102, for example by using a screen (not shown in the figures), so as to obtain a wet pattern 104' on top of substrate 102.

[0053] The substrate 102 may in particular be made of a semiconductor material, for example an n-doped semiconductor material in the upper portion of the substrate 102 (i.e. the portion extending in the y-direction according to the coordinate system 160) and for example a p-doped semiconductor material extending towards the opposite bottom surface (i.e. the surface of the substrate 102 facing the substrate holder 104 and extending in the −y-direction according to the coordinate system 160).

[0054] The conductive paste 104 is used to create a wet pattern 104 ′ (eg, fingers of solar cells or busbars) on top of the substrate 102 , for example by using a screen.

[0055] The laser system 106 is configured to generate a two-dimensional light beam 108 that is incident on the conductive paste 104 at at least one incident segment 140 .

[0056] In some embodiments, the two-dimensional beam 108 and segment 140 are, for example, parallel to the Ozy plane (e.g., Figure 1 The wet conductive paste 104 extends primarily in a vertical direction parallel to the x-axis of the coordinate system 160, while the wet conductive paste 104 extends primarily in a vertical direction parallel to the x-axis of the coordinate system 160. The origin of the Cartesian coordinate system 160Oxyz is indicated by O.

[0057] In other embodiments, the pattern 104′ can have any initial orientation, and the alignment system provides a convenient orientation of the pattern 104′ and / or the substrate relative to the beam 108. For example, the pattern 104′ and / or the substrate can be arbitrarily oriented, and the alignment system orients the substrate such that the pattern 104′ is substantially perpendicular to the two-dimensional beam 108, such as along the x-axis of the coordinate system 160 if the two-dimensional beam 108 is oriented in the Ozy plane of the coordinate system 160.

[0058] In some embodiments, misalignment of the pattern 104 ′ with respect to an axis perpendicular to the two-dimensional light beam 108 up to ±2° can be compensated by the alignment system.

[0059] An alignment system may detect the direction of the pattern 104 ′ and orient the substrate in such a way that the pattern 104 ′ becomes substantially perpendicular to the two-dimensional light beam 108 .

[0060] Thus, in some embodiments, the wet pattern 104 ′ is primarily perpendicular to the two-dimensional light beam 108 .

[0061] In alternative embodiments, the angle between the conductive paste 104 and the light beam 108 may be any angle, particularly an angle greater than zero.

[0062] The y-axis of coordinate system 160 is generally oriented vertically so that gravity acts in the direction The conductive paste 104 is on top of the substrate 102 relative to the earth (ie, relative to gravity).

[0063] Once the light beam 108 reaches the surface of the conductive paste 104 on the substrate 102 at the incident section 104 , the light is reflected back in one or more directions.

[0064] Some reflected light 110 from the light beam 108, which is reflected by the surface of the conductive paste 104 forming the wet pattern 104′, passes through a lens 112. The lens 112 focuses the reflected light 110 onto a light detection device 114. The light detection device 114 is configured to detect two-dimensional light information on the surface of the light detection device 114. The light detection device 114 may be a CCD sensor.

[0065] Therefore, the incident segment 140 is detected by the light detection device 114 based on the reflected light 110 that hits the light detection device at the detection line 180. The detection line 180 is also perpendicular to the Figure 1 The Oxy plane extends along the line of the tangential component.

[0066] The light detection device 114 is capable of detecting characteristics of the entire incident segment 140. For example, let h(z) be the height of the conductive paste 104 at the incident segment 140 corresponding to a point having a z coordinate given by z. For a given z, as h(z) changes, the corresponding point on the detection segment will also change. Therefore, the detection segment 180 indicates the two-dimensional profile of the wet conductive paste 104 along the incident segment 140 characterized by the coordinate z in the set I.

[0067] {(z,h(z))|z∈I},

[0068] For example, where I = [z 最小 ,z 最大 ]Describe the incident section 140.

[0069] The laser system 106 , the lens 112 , and the light detection device 180 are included in the in-line profiler 101 , which is configured to extract three-dimensional morphological data of the wet pattern 104 ′ in real time.

[0070] The online profilometer is capable of repeatedly calculating the two-dimensional profile of the wet conductive paste 104 along the incident segment 140 as the substrate moves parallel to the x-direction.

[0071] {(z,h(z))|z along the incident segment}.

[0072] Alternatively, the in-line profiler may be movable in the x-direction relative to the substrate 102 .

[0073] Let Ox'y'z' be a Cartesian coordinate system fixed to substrate 102 and oriented parallel to Cartesian coordinate system Oxzy 160. Thus, the x-axis is parallel to the x'-axis, the y-axis is parallel to the y'-axis, and the z-axis is parallel to the z'-axis, but while Oxzy is fixed relative to the inline profiler 101 and therefore fixed relative to the laser system 106, the coordinate system Ox'y'z' is fixed relative to substrate 102 and therefore fixed relative to the conductive paste 104 and the wet pattern 104'.

[0074] As the substrate 102 moves relative to the inline profiler 101 (eg, parallel to the x-axis), the surface of the substrate 102 and / or the conductive paste 104 is continuously scanned.

[0075] Thus, each point (x', z') within at least one strip on the substrate 102 is illuminated by the light beam 108 at a certain moment (when the substrate moves relative to the profilometer); the height h(x', z') of the conductive paste 104 at (x', z') is obtained, and thus the set

[0076] M={(x',z',h(x',z'))|the location of (x',z') on the substrate at a certain moment}

[0077] The set M forms the three-dimensional morphological data of the wet pattern 104 ′, and thus the online profiler 101 is able to extract the three-dimensional morphological data M of the wet pattern 104 ′ in real time.

[0078] Computing device 190 may be configured to extract three-dimensional morphological data based at least in part on the light detected by the light detection device.

[0079] The computing device 190 may further include a memory 3031 and / or a controller 3032 .

[0080] The controller 3032 of the computing device 190 may be used to control the deposition of the conductive paste 104 , thereby controlling the printer 192 configured to apply the conductive paste to the substrate.

[0081] The printing press 192 is shown only schematically in the drawings.

[0082] Only schematically shown in Figure 1 The actuator 191 in FIG. 1 may move the substrate holder 120 and the substrate 102 relative to the inline profiler 101 .

[0083] Figure 2 Additional details are shown regarding implementations of the methods and apparatus of the present disclosure.

[0084] Figure 2 Details in the Ozy plane of coordinate system 160 are shown.

[0085] In particular, Figure 2 Details of a multi-head inline profiler 101 are shown according to some embodiments of the present disclosure.

[0086] In some embodiments, the light beam 108 emitted by the laser system 106 may be formed from two or more components that illuminate corresponding portions of the conductive paste 104 forming the wet pattern 104 ′.

[0087] Therefore, in some embodiments, the incident segment 140 may be formed by a union of two or more line segments, that is, in these embodiments,

[0088] I=[z1,z2]∪[z3,z4]∪…

[0089] Where z1≤z2≤z3≤z4≤..., the inline profiler is configured to extract three-dimensional topology data M based on a subset of points of the substrate that are illuminated by the light beam at a certain moment as the substrate moves relative to the profiler.

[0090] For example, z2-z1=6 mm and z4-z3=6 mm. Thus, in some embodiments, the inline profiler 101 can allow inline scanning on two strips each having a width of 6 mm across the entire wafer length of the substrate 102 .

[0091] The light detection device 114 and / or the detection segment 180 allow obtaining information on the height and / or roughness and / or width of the conductive paste 104 .

[0092] The resolution of the topographic data may be, for example, between 1 μm and 10 μm. The substrate 102 placed on the substrate holder 120 may be conveyed by a conveyor belt of the substrate holder, for example, Figure 1 The actuator may be a conveyor belt together with means for imparting movement to said conveyor belt.

[0093] The topography data M can allow the volume of the conductive paste 104 forming the wet pattern 104' to be correlated with the weight of the printed paste and / or to be determined and thus used to calculate the total mass of the printed paste and / or the area density of the printed paste for a given portion of the substrate. The flow rate of the conductive paste deposited on the substrate can be determined.

[0094] Thus, it is possible to determine in real time how much slurry is applied to a given portion of the substrate, and based on this determination, wet slurry deposition can be controlled in real time.

[0095] Once the firing process occurs, it is no longer possible to control the wet slurry deposition because the fingers and / or busbars are finally positioned. Defects can only be detected after firing. Embodiments of the present disclosure allow for real-time control and / or adjustment and / or correction of wet slurry deposition before firing, allowing real-time online adjustment and control of wet slurry deposition to prevent defects from occurring in the first place, thereby improving yield.

[0096] The online profilometer can detect the morphological changes of the conductive paste 104 .

[0097] The morphology data can be used to calculate slurry deposition consistent with offline scale measurements.

[0098] In some embodiments, the three-dimensional shape data M may be divided into blocks, wherein each block describes data of, for example, a finger formed by the conductive paste 104 and / or a bus wetting pattern 104 ′.

[0099] Collect and store three-dimensional morphological data.

[0100] The light beam 108 may form one or more blades configured to scan the conductive paste 104 .

[0101] The angle between the laser system 106 and the light detection device 114 (eg, a CCD camera) remains fixed. The inline profilometer is based on triangulation based on the reflected light 110 .

[0102] The light beam 108 may in particular be blue light.

[0103] The deposition of the conductive paste 104 may be correlated with the three-dimensional topography data.

[0104] Based on the three-dimensional morphology data and / or based on the image captured by the light detection device 114, the height, roughness, and width of the wet pattern 104' formed by the conductive paste 104 can be obtained. Based on the obtained height, roughness, and / or width, the deposition of the conductive paste 104 can be controlled, in particular, the material consumption of the paste can be optimized.

[0105] The methods and apparatus presented herein allow for the use of minimal slurry while simultaneously achieving quality and yield targets. Control of the deposition of the conductive slurry 104 allows for process control, particularly real-time in-line control, to ensure optimal and uniform slurry deposition to achieve target production quality and yield. Effects such as temperature are compensated for in real time, thereby achieving uniform slurry deposition for each processed wafer / substrate and also within a single wafer.

[0106] For example, knowing the slurry area density on the surface of the substrate, optimization of the slurry deposition amount can be performed.Slurry is very expensive, and therefore the method of the present disclosure allows for savings in material and cost.

[0107] The present disclosure overcomes the limitation of measuring the amount of paste before and after the printing process, which is traditionally time-consuming and / or imprecise.

[0108] The present disclosure allows for the measurement of drift, trends and changes in slurry deposition. If drift is detected, closed-loop control is performed using process parameters to keep the slurry deposition process stable.

[0109] The present disclosure allows for many more data points to be obtained than the small number of data points obtained through traditional offline measurements.

[0110] Figure 3 Details of an embodiment of the method 300 of the present disclosure are shown.

[0111] Execution may begin at block 303, where memory 3031 is read to obtain three-dimensional morphological data of a wet pattern (104'). Memory 3031 may not contain any data at the start of execution. A controller 3032 is then used to at least partially control the printing 305 of the wet pattern on a substrate based on the data in memory 3031. If memory 3031 does not contain morphological data, the printing of the wet pattern may be guided by default settings. The wet pattern (104-pattern) is then printed 305 onto the substrate, for example, using a screen printing process. The three-dimensional morphological data is extracted 301 in real time during or after the printing process.

[0112] The term "real-time" is intended to allow extraction of morphological data to occur as early as possible after or during the printing process, although the printing process may need to be completed before meaningful three-dimensional morphological data is obtained. Thus, the term "real-time" does not necessarily imply that three-dimensional morphological data is obtained while the printing process is currently ongoing. Three-dimensional morphological data can be extracted as soon as the data becomes meaningful during or after the printing of the wet pattern is ongoing and / or at least partially completed. The pattern is a wet pattern.

[0113] The three-dimensional topography data, which may also include information about the width and / or roughness and / or height of the wet pattern and / or the conductive paste forming the wet pattern, may then be processed and stored in the memory 3031. The execution in block 303 may use the available and updated data in the memory 3031 as input to the controller 3032, which may improve the control of the printing 305 process based on the updated extracted three-dimensional topography data, such as adjusting the amount of conductive paste applied to the substrate, or optimizing the material consumption of the conductive paste.

[0114] Figure 4 A solar cell related to an embodiment of the present disclosure is shown.

[0115] In particular, solar cell 400 can be characterized by fingers 404 and / or busbars 402 obtained according to the methods of the present disclosure. Wet pattern 104' can be dried to form fingers 404 and / or busbars 402 of solar cell 400.

[0116] Figure 5 A method 500 for printing on a substrate for producing solar cells according to an embodiment of the present disclosure is shown. The method 500 includes printing 501 a wet pattern on the substrate, extracting 503 three-dimensional topography data of the wet pattern in real time using an in-line profilometer; wherein the printing of the wet pattern on the substrate is controlled in real time based at least in part on previous three-dimensional topography data obtained by extracting the three-dimensional topography data.

[0117] Figure 6 and Figure 7 The height of the printed wet patterns for different wafers is shown.

[0118] According to an embodiment of the present disclosure, a wet pattern is printed on a plurality of wafers forming a plurality of substrates.

[0119] Thus, conductive paste deposition occurs for each wafer / substrate of the plurality of wafers / substrates, the conductive paste applied to the wafer / substrate forming a wet pattern associated with that wafer / substrate.

[0120] Successive printings of the wet pattern of n wafers are performed, each printing producing an average height of the printed wet pattern of the corresponding wafer.

[0121] exist Figure 6 and Figure 7 , the average height of the printed wet pattern for the i-th wafer / substrate is indicated by 600-i. Thus, 600-1 indicates the average height of the printed wet pattern for the first wafer / substrate, 600-2 indicates the average height of the printed wet pattern for the second wafer / substrate processed sequentially after the first substrate, and so on for each sequentially processed substrate i.

[0122] Thus, axis 610 indicates a time sequence, where the i-th printed wafer / substrate corresponds to the i-th position, and axis 620 indicates an average height.

[0123] Figure 6 The fluctuation of the average height 600-i of the printed wet pattern of the i-th wafer / substrate is shown. In particular, the fluctuation may show oscillations of the average height, which may or may not be periodic, or show a monotonic decrease or increase.

[0124] Figure 7 A monotonic decrease in the average height 600-i of the printed wet pattern for the i-th wafer / substrate is shown, which may occur, for example, when a gradual degradation process occurs during the printing process.

[0125] The non-constant nature of the average height 600 - i may be caused by various reasons, such as, for example, temperature variations, disturbances, drift, and / or material degradation.

[0126] According to the solutions known to date, the wafers are weighed offline, usually manually and / or at the expense of time. Based on this weight and knowing the weight of the original wafer (for example, based on the previous weight of a wafer without a wet pattern (resulting in the need to weigh it twice)), the amount of conductive paste applied and / or the volume and / or the average height of the conductive paste can conventionally be determined. Due to the time-consuming nature of such offline weighing, it is not possible in the prior art to determine the average height 600-i of the printed wet pattern for each wafer without unacceptable production slowdowns. Therefore, in the prior art, it is only possible to measure, for example, the average height 600-1 of the wet pattern of the first wafer and then the average height 600-x of the x-th wafer, where x is, for example, hundreds or even thousands of wafers later.

[0127] The present disclosure allows for the height of the conductive paste to be determined in real time, thereby allowing the height of the conductive paste applied on the i-th wafer / substrate to be determined with excellent precision and accuracy.

[0128] Thus, the present disclosure overcomes the limitations of the prior art, eliminating the need for expensive manual or off-line weighing and allowing real-time control of printing. Changes in slurry deposition can be tracked and reacted to by controls.

[0129] Figure 8 The height of the printed wet pattern for different wafers as provided by the present disclosure is shown. As shown, the present disclosure allows for a nearly constant average height 600-i of the printed wet pattern for all wafers, whereas the prior art teachings do not allow for such a constant height. The real-time and online control provided by the present disclosure prevents or compensates for variations in the height of the conductive paste, particularly due to degradation processes, temperature drift, consumption of the material used (e.g., of the printing screen), and the like.

[0130] Figure 9 Examples of the height of printed wet patterns obtained using prior art methods are shown.

[0131] When processing a sequence of wafers according to prior art methods, the average height 600 - i of the printed wet pattern for the i-th processed wafer / substrate in the sequence may drift and / or oscillate. Figure 9 The drift resulting in increased wet pattern height is exemplarily shown, i.e., for wafer j processed after wafer i (i.e., for j>i), the average height 600-j of the printed wet pattern of the jth wafer is at least on average greater than or equal to the average height 600-i of the printed wet pattern of the ith wafer.

[0132] Ideally, a target height 901 of the printed wet pattern should be achieved, resulting in an optimal target weight of slurry for the wafer and avoiding waste of slurry, while providing the desired yield and quality.

[0133] In this example, the drift in the height of the wet pattern produces wafers with increased slurry deposition, and therefore, the average height of the printed wet pattern increases over the wafer sequence, resulting in an increasing amount of wasted excess slurry 903 .

[0134] The excess height of the i-th wafer is defined as the average height 600-i of the printed wet patterns of the i-th wafer minus the target height 901 , which corresponds to the excess amount 903 of slurry that is unnecessarily applied and thus wasted.

[0135] In this example, the excess slurry amount 903 increases significantly over time for different wafers, resulting in significant cumulative waste of slurry.

[0136] In the prior art, measurement of the height of the printed wet pattern and / or the amount of slurry is only possible over large time intervals 905, typically hours (e.g., 4 hours or more), taking the wafer offline to measure the height of the wet pattern of the wafer by weighing.

[0137] In this example, only the first and last wafers in the sequence can be weighed (resulting in double weighing at the beginning and end of the sequence). Therefore, in the prior art, the measurement of the amount of slurry and / or the height of the wet pattern occurs only at the beginning and end of the time interval 905, which is typically several hours, and intermediate wafers cannot be weighed during production without incurring an unacceptable loss of time.

[0138] exist Figure 9 , an upper limit 901-1 and a lower limit 901-2 are indicated, which may correspond to a tolerance for deviations from the target height 901. After a few hours, for example when an excess amount of slurry is already noticeable, i.e., when the height 600-i of the printed wet pattern significantly exceeds the upper limit 901-1 or significantly falls below the lower limit 901-2, measurements performed at large time intervals may only detect heights that are out of tolerance, i.e., above the upper limit 901-1 or below the lower limit 901-2.

[0139] Target height 901 corresponds to a target weight, which is defined as the amount of silver paste used to achieve optimal cell efficiency with minimal paste usage. The amount is typically determined prior to production in conjunction with tolerances resulting in an upper limit 901-1 and a lower limit 901-2.

[0140] If the slurry deposited for the battery is greater than the target weight, as in the example, the battery efficiency is ensured, but the slurry consumption is greater than the baseline, resulting in unnecessarily higher costs.

[0141] Conversely, if the slurry deposition is below the target weight, the cell efficiency is lower than the baseline and a "dead cell" is obtained, thereby reducing the yield.

[0142] According to the prior art, at the beginning of time interval 905, the operator starts the machine in nominal conditions and, after time interval 905 has elapsed, typically after a few hours, for example, after 4 hours, the operator weighs the battery again to determine the amount of excess or missing slurry. For this double weighing, the battery is typically taken offline. If the operator finds that the deposition is outside the required tolerance, the deposition is manually adjusted by changing the printing parameters or replacing consumables (such as the printing screen). The operator knows the pre-calculated slurry amount and can make adjustments.

[0143] Figure 10 Shown are examples of the height of printed wet patterns obtained according to embodiments of the present disclosure.

[0144] According to the embodiment exemplarily shown in the figure, the average height 600 - i of the printed wet pattern of the i-th wafer is determined in real time and a manual operator receives information about any deviations outside the limits determined by the tolerances.

[0145] If the height / deposition is out of tolerance, such as exceeding upper limit 1001-1, as is the case with wafer 1003-1, embodiments of the present disclosure allow for detection of the deviation. An alert is sent to the controller and production can be stopped to adjust the slurry deposition.

[0146] For example, the operator checks the cause of the deviation, such as degradation, and changes the parameters to restore nominal conditions. The parameters are adjusted so that the target height 901 is met again. As a result, silver paste is no longer wasted because the deviation out of tolerance is detected immediately, rather than hours later.

[0147] For example, for wafer 1003-2, the height of the deposited, i.e., printed, wet pattern is lower than the target height 901 and lower than the lower limit 1001-2. Embodiments of the present disclosure detect the deviation and send an alarm. The operator manually adjusts the parameters to set the exact target weight again to overcome the deviation.

[0148] Due to the possibility of real-time detection, the width of the interval determined by the lower limit 1001-2 and the upper limit 1001-1 (i.e., the height of the upper limit 1001-1 minus the height of the lower limit 1001-2) is significantly smaller than the difference between the upper limit 901-1 and the lower limit 901-2 in the prior art.

[0149] In particular, the lower limit 1001-2 allows avoiding the average height 600-i of the printed wet pattern being so low as to produce scrap batteries.

[0150] Real-time weight assessment / measurement of each cell allows the process to be controlled with minimal operator intervention, thus avoiding scrapped cells and preventing wasted slurry.

[0151] Figure 11 Shown are examples of the height of printed wet patterns obtained according to embodiments of the present disclosure.

[0152] According to some embodiments of the present disclosure, the deposition of the slurry is controlled by an automatic closed-loop control system, thereby avoiding the need to return to the operator.

[0153] Embodiments of the present disclosure automatically control slurry deposition in a closed-loop manner. If the slurry height increases above or decreases below the target height 901, the automatic control can adjust the slurry deposition in real time to minimize any deviation from the target. In this way, the height of the wet pattern approaches a constant level corresponding to the target height 901 and may only have very small errors, such as the height oscillating closely around the target.

[0154] It is also possible to predict changes in consumables (eg, used screens) and perform preventive interventions, such as accurate preventive maintenance related to consumables.

[0155] For example, due to the real-time nature of extracting 503 the three-dimensional morphological data of the wet pattern using an online profilometer, maintenance can be performed promptly, for example by an operator, at the earliest appropriate moment to optimize costs and material consumption.

[0156] Compared to existing technologies, real-time control allows tolerances to be further reduced and upper and lower limits to be set closer to target levels, providing a near-constant amount of slurry deposition.

[0157] In addition to the foregoing, the present disclosure relates to an in-line profilometer to extract three-dimensional morphological data of dry patterns obtained by firing wet patterns and / or fired metal contacts.

[0158] According to an alternative embodiment, the topography data may be topography data of a stem pattern and / or fired metal contacts forming busbars and / or fingers of a solar cell.

[0159] In some embodiments, the battery can be taken offline to be scanned by the profilometer.

[0160] The profilometer may alternatively be based on interferometry using projections of structured beams and / or different focal points and / or filters. In some embodiments, confocal profiling may be used.

[0161] Hereinafter, embodiments of the present disclosure are described in detail.

[0162] Some embodiments disclose a method 500 for printing on a substrate for producing solar cells, the method comprising:

[0163] printing 501 a wet pattern on a substrate 102;

[0164] The 3D morphological data of the 503 wet pattern was extracted in real time using an online profilometer;

[0165] Wherein printing of the wet pattern on the substrate is controlled in real time based at least in part on previous three-dimensional topography data obtained by extracting the three-dimensional topography data.

[0166] In some embodiments, the morphological data comprises a height of the printed wet pattern that depends at least in part on (e.g., varies with) a two-dimensional position relative to the substrate, and / or wherein the morphological data further allows for determination of thickness and / or width and / or volume and / or roughness data of the printed wet pattern, and wherein printing of the wet pattern on the substrate is controlled in real time based at least in part on the determined height and / or thickness and / or width and / or volume and / or roughness data of the printed wet pattern.

[0167] In some embodiments, printing the wet pattern includes depositing a conductive paste on the substrate, and extracting the three-dimensional morphology data allows real-time determination of the amount of conductive paste on the substrate and / or the flow rate of the conductive paste deposited on the substrate; and real-time control and / or real-time adjustment of the conductive paste deposition based on the determined amount and / or flow rate.

[0168] In some embodiments, the topography data includes a height relative to the substrate of at least each point within a rectangular swath scanned by the in-line profilometer.

[0169] In some embodiments, the topography data includes the height relative to the substrate of each point within two rectangular strips scanned by the in-line profilometer, particularly where the in-line profilometer is a multi-head profilometer.

[0170] In some embodiments, the substrate moves relative to the inline profiler in a first direction; and the inline profiler is a 3D laser profiler that shines light on the substrate along a substantially linear segment or a combination of substantially linear segments extending in a direction substantially perpendicular to the first direction.

[0171] In some embodiments, the 3D laser profiler irradiates blue light and obtains three-dimensional topography data based on reflection of the blue light on the wet pattern on the substrate, particularly the blue light has a wavelength, such as 405 nm.

[0172] In some embodiments, the wavelength may be determined or adjusted based on the substrate, for example, to maximize the reflection of light. Thus, the wavelength may depend on the substrate used so that it is within the range of light that is actually reflected by the substrate with sufficient intensity. Wafers of different colors (i.e., reflecting different wavelengths) may require a different wavelength from the incident light illuminated by the 3D laser profiler to maximize the light reflected by the substrate.

[0173] In some embodiments, the wet pattern is a wet pattern of fingers of a solar cell and / or a busbar.

[0174] Some embodiments disclose a method for optimizing material consumption during production of solar cells, the method comprising:

[0175] Printing on a substrate 102 for producing solar cells according to the method of the present disclosure;

[0176] Determine material consumption based on the extracted 3D morphological data;

[0177] Optimize material consumption;

[0178] Wherein the material consumption is the consumption of the material used to print the wet pattern on the substrate;

[0179] Some embodiments describe an apparatus for printing on a substrate 102 for producing solar cells, the apparatus comprising:

[0180] substrate holder 120;

[0181] Online profilometer 101;

[0182] an actuator 191 coupled to the substrate holder 120;

[0183] a printer 192 for applying a wet pattern on the substrate 102;

[0184] A controller is coupled to the in-line profilometer and the actuator and to the printer and is configured to control printing of the wet pattern on the substrate.

[0185] wherein the online profilometer 101 is configured to extract three-dimensional morphological data of a wet pattern on a substrate 102 placed on a substrate holder in real time;

[0186] In some embodiments, the online profiler 101 includes:

[0187] a laser system 106 configured to impinge a two-dimensional light beam 108 on the wet pattern in at least one impingement section 140 ;

[0188] - and / or a light detection device 114 configured to detect two-dimensional light information;

[0189] - and / or a lens 112 system configured to capture light reflected from the wet pattern at at least one incident segment and / or direct the reflected light (110) to a light detection device 114 such that two-dimensional reflected light information is detected by the light detection device 114;

[0190] - and / or a computing device 190 configured to extract three-dimensional morphological data based at least in part on the light detected by the light detection device.

[0191] In some embodiments, the actuator coupled to the substrate holder is a linear actuator or conveyor configured to move the substrate linearly in a direction substantially perpendicular to the at least one incident segment.

[0192] In some embodiments, the light beam is formed of blue light, particularly blue light having a wavelength of 405 nm.

[0193] In some embodiments, the printer 192 and controller are configured to print a wet pattern based on three-dimensional morphological data previously extracted by the inline profilometer 101 .

[0194] In some embodiments, the topography data includes a height of the wet pattern based at least in part on a two-dimensional position relative to the substrate, and / or the topography data further allows for determination of a width and / or roughness of the wet pattern, and the controller controls printing of the wet pattern in real time based at least in part on the height and / or width and / or roughness of the wet pattern.

[0195] In some embodiments, the topography data includes a height relative to the substrate of at least each point within a rectangular swath scanned by the in-line profilometer.

[0196] In some embodiments, the topography data includes the height relative to the substrate of each point within two rectangular strips scanned by the in-line profilometer, particularly where the in-line profilometer is a multi-head profilometer.

[0197] A pattern is made from a conductive paste with a predefined geometry, such as a wet conductive paste or a dry conductive paste, which, once fired, forms the fingers and / or busbar metal contacts of the solar cell according to the predefined geometry. The wet pattern is formed from the wet paste; the dry pattern is formed from the dry paste; and the finger or busbar metal contacts are formed from the pattern after firing. The metal contacts can be defined as the fired pattern.

[0198] In the following, further embodiments are described.

[0199] Some embodiments describe a method 500 for printing on a substrate for producing solar cells, the method comprising:

[0200] Printing 501 a wet pattern 104 ′ on the substrate 102 , the wet pattern being formed of a wet conductive paste;

[0201] drying the wet pattern to obtain a dry pattern and firing the substrate having the dry pattern to obtain finger and / or busbar metal contacts on the substrate;

[0202] extracting 503 three-dimensional morphological data of the wet pattern 104 ′ and / or the dry pattern and / or the fingers and / or the busbar metal contacts using the profilometer 101 ;

[0203] In some embodiments, the profilometer is an online profilometer.

[0204] In some embodiments, the substrate is taken offline before the three-dimensional topography data is extracted.

[0205] In some embodiments, the profiler is a laser profiler based on optical triangulation.

[0206] In some embodiments, the profilometer is based on interferometry and / or confocal profilometry.

[0207] In some embodiments, a stylus profilometer is used to extract three-dimensional morphological data of the stem pattern and / or the fingers and / or the busbar metal contacts.

[0208] In some embodiments, the morphological data includes heights of the printed wet and / or dry patterns and / or fingers and / or busbar metal contacts at least in part based on a two-dimensional position relative to the substrate, and / or the morphological data further allows for determination of width and / or roughness data of the printed wet and / or dry patterns and / or fingers and / or busbar metal contacts.

[0209] In some embodiments, the morphological data further includes information about the roughness and / or width and / or height of the conductive paste and / or wet pattern, such as information obtained based on light detected by a light detection device (e.g., a CCD camera) and / or information obtained by a data processing algorithm, in particular based on light detected by the light detection device 114 and / or the position of the detection segment 180.

[0210] In some embodiments, printing of a wet pattern on a substrate is controlled based at least in part on prior three-dimensional topography data obtained by extracting the three-dimensional topography data.

[0211] In some embodiments, the topography data includes a height relative to the substrate of at least each point within a rectangular swath scanned by the profilometer.

[0212] In some embodiments, the topography data includes the height relative to the substrate of each point within two rectangular swaths scanned by the profiler, particularly if the profiler is a multi-head laser profiler based on optical triangulation.

[0213] In some embodiments, the substrate moves relative to the profiler in a first direction; and wherein the profiler is a 3D laser profiler that shines light onto the substrate along a substantially linear segment or a combination of substantially linear segments extending in a direction substantially perpendicular to the first direction.

[0214] In some embodiments, a 3D laser profiler irradiates blue light, such as 405 nm blue light, and obtains three-dimensional topography data based on reflection of the blue light on the wet pattern and / or dry pattern and / or fingers and / or busbar metal contacts on the substrate.

[0215] In some embodiments, printing the wet pattern includes depositing a conductive paste on the substrate, and extracting the three-dimensional topography data includes extracting the three-dimensional topography data of the wet pattern in real time and allowing real-time determination of the amount and / or area density of the conductive paste on the surface of the substrate and / or determination of the flow rate of the conductive paste deposited on the substrate. The conductive paste deposition is controlled and / or adjusted based on the determined amount of the conductive paste on the substrate and / or based on the area density of the conductive paste on the surface of the substrate and / or based on the flow rate of the conductive paste deposited on the substrate.

[0216] In some embodiments, the wet pattern is a wet pattern of fingers of a solar cell and / or a busbar.

[0217] Some embodiments of the present disclosure describe a method for optimizing material consumption during production of solar cells, the method comprising:

[0218] Printing according to the method of the present disclosure on a substrate for producing solar cells;

[0219] Determine material consumption based on the extracted 3D morphological data;

[0220] Optimize material consumption;

[0221] Wherein the material consumption is the consumption of the material used to print the wet pattern on the substrate;

[0222] Some embodiments of the present disclosure describe an apparatus for printing on a substrate 102 for producing solar cells, the apparatus comprising

[0223] substrate holder 120;

[0224] Online profilometer 101;

[0225] an actuator coupled to the substrate holder;

[0226] a printer (192) for applying a wet pattern on a substrate;

[0227] The online profiler 101 is configured to extract three-dimensional morphological data of a wet pattern 104 ′ on a substrate 102 placed on a substrate holder in real time.

[0228] The solar cell is scanned by a profiler over a wide area (e.g., the entire cell area). Either the cell is moved relative to the profiler, or the profiler is moved relative to the cell. The cell can be removed from normal flow. The cell can remain online.

[0229] In some embodiments, the online profiler 101 includes:

[0230] a laser system 106 configured to generate a two-dimensional light beam 108 incident on the wet pattern 104 ′ on at least one incident segment 140 ;

[0231] - and / or a light detection device 114 configured to detect two-dimensional light information;

[0232] - and / or a lens 112 system configured to capture light reflected from the wet pattern at at least one incident segment and / or to direct the reflected light 110 to a light detection device 114 such that two-dimensional reflected light information is detected by the light detection device 114;

[0233] - and / or a computing device configured to extract three-dimensional morphological data based at least in part on the light detected by the light detection device.

[0234] In some embodiments, the actuator coupled to the substrate holder is a linear actuator or a conveyor or a conveyor belt configured to move the substrate linearly in a direction substantially perpendicular to the at least one incident segment.

[0235] In some embodiments, the light beam is formed from blue light.

[0236] In some embodiments, printer 192 or slurry deposition equipment is configured to print a wet pattern based on three-dimensional topography data previously extracted by in-line profilometer 101 .

[0237] The printer can be controlled by a controller 3032 that receives three-dimensional topography data, which can be stored in a memory 3031. The memory 3031 and / or the controller 3032 can be part of a computing device 190 coupled to the light detection device 114. The computing device 190 coupled to the light detection device 114 can obtain the three-dimensional topography data, store the three-dimensional topography data in the memory 3031, and control the controller 3032 and the printer 192, particularly controlling the amount of conductive paste 104 applied to the substrate 102 to form the wet pattern 104′.

[0238] The computing device 190 , the memory 3031 , and the controller 3032 are part of the online profiler 101 .

[0239] In some embodiments, the topography data includes a height of the wet pattern that is at least partially dependent on the two-dimensional position relative to the substrate, and / or the topography data further allows for determination of the width and / or roughness of the printed wet pattern. For example, the height of the wet pattern can be a function of the two-dimensional position / location relative to the substrate.

[0240] In some embodiments, the topography data includes a height relative to the substrate of at least each point within a rectangular swath scanned by the in-line profilometer.

[0241] In some embodiments, the topography data includes the height relative to the substrate of each point within two rectangular strips scanned by the in-line profilometer, particularly where the in-line profilometer is a multi-head profilometer.

Claims

1. A method for optimizing material consumption during solar cell production, the method comprising: Printing on a substrate (102) for producing the solar cell; Determine material consumption based on the extracted 3D morphological data; optimizing said material consumption; wherein the material consumption is the consumption of the material used to print the wet pattern on the substrate; And wherein the step of printing on the substrate for producing the solar cell comprises: printing (501) a wet pattern on the substrate (102); extracting (503) three-dimensional morphological data of the wet pattern (104') in real time using an online profilometer (101); wherein printing of the wet pattern on the substrate is controlled in real time based at least in part on previous three-dimensional topology data obtained by extracting the three-dimensional topology data, wherein controlling the printing of the wet pattern on the substrate comprises controlling the amount of the material applied to the substrate to form the wet pattern; And wherein the real-time control compensates for changes in the height of the material due to at least one of degradation processes, temperature drift, and consumption of the material used.

2. The method of claim 1 , wherein the topography data comprises a height of the printed wet pattern that depends at least in part on a two-dimensional position relative to the substrate, or wherein the topography data further allows determination of a thickness or width or volume or roughness data of the printed wet pattern, and wherein printing of the wet pattern on the substrate is controlled in real time based at least in part on one or more of the determined height, thickness, width, volume, roughness data of the printed wet pattern.

3. The method of claim 1 , wherein printing the wet pattern comprises depositing a conductive paste on the substrate, and extracting the three-dimensional morphology data allows for real-time determination of an amount of the conductive paste on the substrate or a flow rate of the conductive paste deposited on the substrate; and wherein the conductive paste deposition is controlled or adjusted in real-time based on the determined amount or flow rate.

4. The method of claim 1, wherein the topography data comprises a height relative to the substrate of each point within at least a rectangular strip scanned by the in-line profilometer.

5. The method of claim 4, wherein the topography data comprises a height relative to the substrate of each point within two rectangular strips scanned by the in-line profilometer. The method of claim 5 , wherein the online profilometer is a multi-head profilometer.

7. The method of claim 1 , wherein the substrate moves relative to the online profiler along a first direction; and wherein the online profiler is a 3D laser profiler that illuminates light onto the substrate along a substantially linear segment or a combination of substantially linear segments extending in a direction substantially perpendicular to the first direction. 8 . The method of claim 7 , wherein the 3D laser profiler irradiates light having a predetermined wavelength, and wherein the three-dimensional topography data is obtained based on reflection of the light on the wet pattern on the substrate. 9 . The method of claim 8 , wherein the light is blue light having a wavelength of 405 nm, or wherein the wavelength of the light is adjusted based on the substrate to maximize reflection of the light by the substrate.

10. The method of any one of claims 1 to 9, wherein the wet pattern is a wet pattern of fingers or busbars of the solar cell.

11. An apparatus for printing on a substrate (102) for producing solar cells, the apparatus comprising: a substrate holder (120); Online profilometer (101); an actuator (191) coupled to the substrate holder (120); a printer (192) for applying a wet pattern (104') on the substrate (102); a controller coupled to the inline profilometer and the actuator and the printer and configured to control printing of the wet pattern on the substrate in real time; wherein the online profilometer (101) is configured to extract three-dimensional morphological data of the wet pattern (104') on the substrate (102) placed on the substrate holder in real time; and wherein the controller is further configured to determine material consumption based on the extracted three-dimensional morphological data and optimize the material consumption; wherein the material consumption is the consumption of the material used to print the wet pattern on the substrate, wherein controlling the printing of the wet pattern on the substrate comprises controlling the amount of the material applied to the substrate to form the wet pattern; And wherein the real-time control compensates for changes in the height of the material due to at least one of degradation processes, temperature drift, or consumption of the material used.

12. The apparatus of claim 11, wherein the online profiler (101) comprises one or more of: a laser system (106) configured to generate a two-dimensional light beam (108) incident on the wet pattern (104') at at least one incident segment (140); - a light detection device (114) configured to detect two-dimensional light information; a lens (112) system configured to capture light reflected from the wet pattern at the at least one incident segment or to direct the reflected light (110) to the light detection device (114), so that two-dimensional reflected light information is detected by the light detection device (114); - a computing device (190) configured to extract the three-dimensional morphological data based at least in part on the light detected by the light detection device.

13. The apparatus of claim 12, wherein the actuator coupled to the substrate holder is a linear actuator or a conveyor configured to linearly move the substrate in a direction substantially perpendicular to the at least one incident segment.

14. The apparatus of claim 12, wherein the light beam is formed of blue light having a wavelength of 405 nm.

15. The apparatus of claim 11, wherein the printer (192) and the controller are configured to print the wet pattern based on three-dimensional morphological data previously extracted by the in-line profilometer (101).

16. The apparatus of claim 11 , wherein the topography data comprises a height of the wet pattern that depends at least in part on a two-dimensional position relative to the substrate, or the topography data further allows determination of a width or roughness of the wet pattern, and the controller controls printing of the wet pattern in real time based at least in part on the height or the width or the roughness of the wet pattern.

17. The apparatus of claim 11, wherein the topography data comprises a height relative to the substrate of each point within at least a rectangular strip scanned by the inline profilometer.

18. The apparatus of claim 17, wherein the topography data comprises a height relative to the substrate of each point within two rectangular strips scanned by the in-line profilometer.

19. The apparatus of claim 18, wherein the in-line profilometer is a multi-head profilometer.

Images