Patent Description:
The mostly used method of printing high viscosity paste in solar PV and electronics industries is a screen printing. In this method the mesh screen contacts the receiving substrate, the paste is pushed through openings in the screen and the printed pattern copies the pattern of the screen. The receiving substrate and the screen are stationary during printing so the deposited paste pattern cannot be changed during printing (see for example <NPL>).

<CIT> (and <CIT>) teaches a method of depositing a material on a receiving substrate, the method comprising: providing a source substrate having a back surface and a front surface, the back surface carrying at least one piece of coating material; providing a receiving substrate positioned adjacent to the source substrate and facing the coating material; and radiating light towards the front surface of the source substrate, to remove at least one piece of the coating material from the source substrate and deposit said removed at least one piece onto the receiving substrate as a whole. In this method source substrate, which defines the pattern to be deposited, does not contact the receiving substrate. The source and receiving substrates are stationary during printing therefore the deposited paste pattern copies the pattern of the source substrate and cannot be changed during printing.

One aspect of the present invention provides a dynamic pattern transfer printing system according to claim <NUM>, namely a dynamic pattern transfer printing system comprising: at least one laser scanner configured to illuminate with at least one laser beam a source substrate that comprises a plurality of trenches arranged in a first pattern and holding printing paste, wherein the source substrate is configured to release the printing paste from the trenches and onto a receiving substrate upon the illumination by the laser beam, a moveable stage supporting the receiving substrate, wherein the receiving substrate is affixed to the moveable stage during the releasing of the printing paste from the source substrate, and a controller configured to control the laser beam illumination along the trenches, and at a scanning direction across the trenches, and further configured to move the moveable stage to yield a second pattern of deposited paste on the receiving substrate, which is different from the first pattern of trenches on the source substrate, wherein the first pattern of trenches on the source substrate has a first pitch (p1) and the second pattern of deposited paste on the receiving substrate has a second pitch (p2) and wherein the controller is configured to move the moveable stage in at least one of: the scanning direction, to yield the second pattern on the receiving substrate, wherein the first pitch (p1), the second pitch (p2), a forward speed of the moveable stage (vF) and a scanner speed across the trenches (vS) are configured to have the relation p2=p1·(vS-vF)/vS to make the second pitch smaller than the first pitch (p2<p1); and/or against the scanning direction, to yield the second pattern on the receiving substrate, wherein the first pitch (p1), the second pitch (p2), a backward speed of the moveable stage (vB) and a scanner speed across the trenches (vS) are configured to have the relation p2=p1·(vS+vB)/vS to make the second pitch larger than the first pitch (p2>p1).

One aspect of the present invention provides a dynamic pattern transfer printing method according to claim <NUM>, namely a dynamic pattern transfer printing method comprising: illuminating a source substrate with at least one laser beam, wherein: the source substrate comprises a plurality of trenches arranged in a first pattern and holding printing paste, the source substrate is configured to release the printing paste from the trenches and onto a receiving substrate upon the illumination by the laser beam, and the illuminating is carried out along the trenches, and at a scanning direction across the trenches; and controllably moving the receiving substrate to yield a second pattern of deposited paste on the receiving substrate, which is different from the first pattern of trenches on the source substrate, wherein the first pattern of trenches on the source substrate has a first pitch (p1) and the second pattern of deposited paste on the receiving substrate has a second pitch (p2) and wherein the controller is configured to move the moveable stage in at least one of: the scanning direction, to yield the second pattern on the receiving substrate, wherein the first pitch (p1), the second pitch (p2), a forward speed of the moveable stage (vF) and a scanner speed across the trenches (vS) are configured to have the relation p2=p1·(vS-vF)/vS to make the second pitch smaller than the first pitch (p2<p1). ; and/or against the scanning direction, to yield the second pattern on the receiving substrate, wherein the first pitch (p1), the second pitch (p2), a backward speed of the moveable stage (vB) and a scanner speed across the trenches (vS) are configured to have the relation p2=p1·(vS+vB)/vS to make the second pitch larger than the first pitch (p2>p1).

One aspect of the present invention provides a computer program product according to claim <NUM>, namely a computer program product comprising a non-transitory computer readable storage medium having computer readable program embodied therewith, the computer readable program configured to carry out the above mentioned dynamic pattern transfer printing method.

One aspect of the present invention provides a pattern transfer sheet according to claim <NUM>, namely a a pattern transfer sheet comprising: a plurality of groups of trenches and configured to receive printing paste and release the printing paste from the trenches upon illumination by a laser beam onto a receiving substrate, wherein a pitch of the trenches in each group is constant, the groups are separated by gaps, and the pitch among groups varies.

Embodiments of the present invention provide efficient and economical methods and mechanisms for improving pattern transfer printing (PTP) and thereby provide improvements to the technological field of wafer production. Dynamic pattern transfer printing systems and methods are provided, which decouple the design of the trench patterns on a source substrate for pattern transfer printing, from the resulting metallic paste lines patterns transferred to a receiving substrate, such as PV cells. In various embodiments, disclosed PTP systems and methods may be configured to print fine lines of thick metallic paste to produce electronic circuits, e.g., to create conductive lines or pads or other features on laminates for PCBs (printed circuit boards) or other printed electronic boards. Other applications may comprise creating conductive features in the manufacturing processes of mobile phones antennas, decorative and functional automotive glasses, semiconductor integrated circuits (IC), semiconductor IC packaging connections, PCB features and components assemblies, optical, biological, chemical and/or environment sensors and detectors, radio frequency identification (RFID) antennas, organic light-emitting diode (OLED) displays (passive or active matrix), OLED illuminations sheets, printed batteries and other applications - any of which may comprise the receiving substrate. The receiving substrate may be moved forward (along the scanning direction of the laser illumination used to transfer the paste from the trenches onto the receiving substrate) to reduce the pattern pitch with respect to the source substrate, and/or the receiving substrate may be moved backward (against the scanning direction) to increase the pattern pitch with respect to the source substrate. For example, dynamic pattern transfer printing may be used to accommodate different widths of the substrates for the same width of the source substrate, and/or to enable one-to-many pattern transfer technologies with high wafer printing throughput. Also, pattern transfer sheet with separate multiple groups of trenches are provided, such as pattern transfer sheets having multiple groups of trenches, which are configured to receive printing paste and release the printing paste from the trenches upon illumination by a laser beam onto a receiving substrate, wherein a pitch of the trenches in each group is constant and the groups are separated by gaps.

In several industrial applications there is a need to adapt the existing pattern of the source substrate according to changing target locations of printed lines on the receiving substrate and to increase the throughput of the pattern transfer system. The relative movement of the receiving substrate vs. stationary source substrate during printing, which is possible only by using a non-contact printing method like the PTP, provides pattern transfer flexibility that enables adapting the existing pattern of the source substrate according to changing target locations of printed lines on the receiving substrate. Moreover, disclosed pattern transfer sheets enable pattern transfer printing in a one-to-many mode, from one source substrate onto multiple wafer - to increase the throughput of the pattern transfer system.

<FIG> are high-level schematic illustrations of a dynamic pattern transfer printing system <NUM>, according to some embodiments of the invention.

Dynamic pattern transfer printing system <NUM> comprises at least one laser scanner optical head(s) <NUM> configured to illuminate with at least one laser beam <NUM> a source substrate <NUM> that comprises a plurality of trenches <NUM> arranged in a first pattern <NUM> and holding printing paste <NUM>. Source substrate <NUM> is configured to release printing paste <NUM> from trenches <NUM> onto a receiving substrate <NUM> (indicated schematically as pattern transfer <NUM>) upon the illumination by laser beam <NUM> (see e.g., <FIG>). Laser scanner optical head(s) <NUM> may configured to have a fast-scanning axis along a machine direction <NUM> (MD) and may be moved along a cross machine direction <NUM> (CMD).

For example, as illustrated schematically in <FIG>, source substrate <NUM> may comprise a pattern transfer sheet, made e.g., of transparent polymer material, with trenches <NUM> having any of various profiles (cross section shapes), such as trapezoid, rounded, square, rectangular and/or triangular profiles. The polymer material and trench profile may be configured to release paste <NUM> that is filled into them - upon the illumination by laser beam <NUM>. In certain embodiments, trenches <NUM> may be embossed, press molded, pneumatically molded, or laser molded onto source substrate <NUM> during a production process. Trenches <NUM> may be filled with paste <NUM> (as for example described in <CIT>) within dynamic pattern transfer printing system <NUM>, prior to the illumination. Source substrate <NUM> may be made of a single layer or of two or more layers attached to each other, e.g., with one layer being embossed or molded, and another layer providing mechanical strength to source substrate <NUM>. For example, source substrate <NUM> may comprise a top polymer layer <NUM> and a bottom polymer layer <NUM>. In some embodiments, top polymer layer <NUM> may be made of semi-crystalline polymer and have a melting temperature below <NUM>, e.g., below <NUM>, below <NUM>, below <NUM> or have intermediate values. In some embodiments, top polymer layer <NUM> may be made of amorphous polymer and have a glass temperature below <NUM>, e.g., below <NUM>, below <NUM>, below <NUM> or have intermediate values. Bottom polymer layer <NUM> may have a higher melting temperature than the melting temperature or the glass temperature of top polymer layer <NUM>. For example, bottom polymer layer <NUM> may have a melting temperature above <NUM>, above <NUM> (e.g., bi-axially-oriented polypropylene), above <NUM>, and up to <NUM> (e.g., certain polyimides), or have intermediate values.

In various embodiments, polymer layers <NUM>, <NUM> may be made of at least one of: polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, fully aromatic polyester, other copolymer polyester, polymethyl methacrylate, other copolymer acrylate, polycarbonate, polyamide, polysulfone, polyether sulfone, polyether ketone, polyamideimide, polyether imide, aromatic polyimide, alicyclic polyimide, fluorinated polyimide, cellulose acetate, cellulose nitrate, aromatic polyamide, polyvinyl chloride, polyphenol, polyarylate, polyphenylene sulfide, polyphenylene oxide, polystyrene, or combinations thereof - as long as top polymer layer <NUM> has a melting or glass transition temperature (Tm/Tg) below the melting or glass transition temperature (Tm/Tg ) of bottom polymer layer <NUM> and/or as long as bottom polymer layer <NUM> is not affected by the processing conditions of top polymer layer <NUM>.

In certain embodiments, top and bottom polymer layers <NUM>, <NUM> (respectively) may be between <NUM> and <NUM> thick, e.g., between <NUM> and <NUM> thick, between <NUM> and <NUM> thick, between <NUM> and <NUM> thick, or have other intermediate values - with bottom polymer layer <NUM> being preferably at least as thick as top polymer layer <NUM>. The polymer layers may be attached by an adhesive layer <NUM> that is thinner than <NUM> (e.g., thinner than <NUM>, thinner than <NUM>, thinner than <NUM>, thinner than <NUM> or have intermediate values) and is likewise transparent to the laser illumination. For example, in certain embodiments, top polymer layer <NUM> may be thicker than the depth of trenches <NUM> by several µm, e.g., by <NUM>, by <NUM>-<NUM>, by <NUM>-<NUM>, or by up to <NUM>. For example, trenches <NUM> may be <NUM> deep, top polymer layer <NUM> may be <NUM>-<NUM> thick and bottom polymer layer <NUM> may range in thickness between <NUM> and <NUM> (it is noted that thicker bottom polymer layer provide better mechanical performances). It is noted that the term "trenches" is not to be construed as limiting the shape of trenches <NUM> to linear elements, but is understood in a broad sense to include any shape of trenches <NUM>.

The temperature and thickness of top and bottom polymer layers (<NUM>, <NUM> respectively) may be designed so that top polymer layer <NUM> has good molding, ductility and certain mechanical strength, while bottom polymer layer <NUM> has good mechanical strength. Both top and bottom polymer layers (<NUM>, <NUM> respectively) may be designed to have good bonding properties.

Receiving substrate <NUM> may comprise a silicon wafer, as used, e.g., for manufacturing PV cells of different types as described in detail, e.g., in Luque and Hegedus (eds. ) <NUM>, Handbook of photovoltaic science and engineering, pages <NUM>-<NUM>. In various embodiments, receiving substrate <NUM> may comprise any type of electronic circuits, e.g., PCBs or other printed electronic boards, mobile phones antennas, decorative and functional automotive glasses, semiconductor integrated circuits (IC), semiconductor IC packaging connections, optical, biological, chemical and/or environment sensors and detectors, radio frequency identification (RFID) antennas, organic light-emitting diode (OLED) displays (passive or active matrix), OLED illuminations sheets, printed batteries and other applications.

Dynamic pattern transfer printing system <NUM> further comprises a moveable stage <NUM> supporting receiving substrate <NUM>, with receiving substrate <NUM> being affixed (e.g., by help of vacuum clamping) to moveable stage <NUM> during the releasing of printing paste <NUM> from source substrate <NUM> (see e.g., <FIG>). Moveable stage <NUM> may comprise any type of stage or wafer holder that can affix and move receiving substrate <NUM>. Moveable stage <NUM> may be moved by any type of actuator, e.g., by linear or step motors.

Dynamic pattern transfer printing system <NUM> further comprises a controller <NUM> configured to control laser scanner optical head <NUM> to direct laser beam <NUM> along trenches <NUM> (along machine direction <NUM> - MD), and at a scanning direction <NUM> (CMD - cross machine direction) across trenches <NUM>. Controller <NUM> is further configured to move moveable stage <NUM> (the movements are denoted schematically by numeral <NUM>) to yield a second pattern <NUM> of deposited paste on receiving substrate <NUM>, which is different from first pattern <NUM> of trenches <NUM> on source substrate <NUM>. Advantageously, in contrast to current practice which is limited to transferring the same pattern (e.g., of lines) from source substrate <NUM> to receiving substrate <NUM>, various embodiments of dynamic pattern transfer printing system <NUM> enable to deposit the transferred metal paste onto receiving substrate <NUM> at patterns (second pattern <NUM>) which are different from first pattern <NUM> of trenches <NUM> on source substrate <NUM>, as explained in further details below.

It is noted that scanning <NUM> is carried out in one or two directions, and respective movements <NUM> of receiving substrate <NUM> are adjusted accordingly. In the present disclosure scanning direction <NUM> is illustrated in one direction, as a non-limiting example.

First pattern <NUM> of trenches <NUM> on source substrate <NUM> has a first pitch ("p<NUM>") and second pattern <NUM> of deposited paste on receiving substrate <NUM> has a second pitch ("p<NUM>"), that is smaller or larger than first pitch ("p<NUM>"), p<NUM>>p<NUM> or p<NUM><p<NUM>. It is noted that second pattern <NUM> may differ from first pattern <NUM> over the whole extent of receiving substrate <NUM>, over part of the extent of receiving substrate <NUM>, or possibly the way second pattern <NUM> differs from first pattern <NUM> may vary across the extent of receiving substrate <NUM>, for example, in some area(s) of receiving substrate <NUM> the difference may comprise p<NUM>>p<NUM> while in other area(s) of receiving substrate <NUM> the difference may comprise p<NUM><p<NUM>.

With first pitch p<NUM> being larger than second pitch p<NUM>(p<NUM>>p<NUM>), controller <NUM> is configured to move moveable stage <NUM> along scanning direction <NUM> (CMD, denoted 110A) at a forward speed set to convert first pitch p<NUM> to second pitch p<NUM>. With forward speed 110A denoted as vF and the time between deposition of consecutive lines denoted as t, p<NUM>=p<NUM>-vF·t. Denoting the scanner speed <NUM> across trenches <NUM> as vS=p<NUM>/t, the relation between the pitches is p<NUM>=p<NUM>·(vS-vF)/vS.

With first pitch p<NUM> being smaller than second pitch p<NUM> (p<NUM><p<NUM>), controller <NUM> is configured to move moveable stage <NUM> against (in a contrary direction to) scanning direction <NUM> (CMD, denoted 110B) at a backward speed set to convert first pitch p<NUM> to second pitch p<NUM>. With backward speed 110B denoted as vB and the time between deposition of consecutive lines denoted as t, p<NUM>=p<NUM>+vB·t. Denoting the scanner speed <NUM> across trenches <NUM> as vS=p<NUM>/t, the relation between the pitches is p<NUM>=p<NUM>·(vS+vB)/vS.

<FIG> is a high-level schematic illustration of modifications of the transferred pattern by dynamic pattern transfer printing system <NUM>, according to some embodiments of the invention. <FIG> illustrates schematically the modification of the pitch of the stationary trench pattern during printing. Source substrate <NUM> may comprise a plurality of substantially parallel trenches <NUM> arranged with a certain source pitch p<NUM>. Source substrate <NUM> may be configured to receive printing paste <NUM> and release the printing paste from trenches <NUM> upon illumination by a laser beam <NUM> onto receiving substrate <NUM> (see also <FIG>). Receiving substrate <NUM> (e.g., a wafer) may comprise a pattern of substantially parallel linear locations arranged with a certain receiving pitch p<NUM>, for receiving the paste release from trenches <NUM> of source substrate <NUM>, in a close proximity to source substrate <NUM> in such a way that the first trench on source substrate <NUM> is located exactly opposite to the first linear location on receiving substrate <NUM>. Scanning the paste-filled trench pattern (<NUM>) on source substrate <NUM> by laser beam <NUM> sequentially from the first trench to the last trench results is deposition of the paste onto the specified locations on receiving substrate <NUM> to yield deposited paste in the specified pattern (<NUM>). As controller <NUM> moves receiving substrate <NUM> during the scanning, the paste is deposited at a different pitch (p<NUM>≠p<NUM>), depending on the direction and speed of motion.

For example, paste deposition on receiving substrate <NUM> at different pattern <NUM> than pattern <NUM> on source substrate <NUM> may be especially useful in printing conducting lines (fingers) on crystalline silicon PV cells (wafers) that comprise a pattern of narrow selective emitter (SE) lines (see for example in Luque and Hegedus (eds. ) <NUM>, Handbook of photovoltaic science and engineering, pages <NUM>-<NUM>). In a non-limiting example, the finger width on receiving substrate <NUM> may be <NUM> and the required SE line width may be <NUM> - leaving a tolerance for locating the finger within the SE line to be only about ±<NUM> (assuming that the SE lines pitch is uniform over the wafer).

In current practice, the pitch of the SE lines may be a little bit different from the pitch of the trenches or be non-uniform over the silicon wafer, so the fingers printed from the stationary source substrate with a constant source pitch do not fall exactly into the predefined SE lines. This requires increasing the SE line width that causes PV cell efficiency reduction.

In contrast, in various embodiments, dynamic pattern transfer printing system <NUM> may be configured to yield wafers 70A, 70B with lines 75A, 75B that are spaced narrower or broader from each other (respectively) according to specified requirements. For example, lines 75A may be narrower spaced than trenches <NUM> (p<NUM><p<NUM>) by applying forward movement 110A while lines 75B may be wider spaced than trenches <NUM> (p<NUM>>p<NUM>) by applying backward movement 110B. Clearly, line spacing on receiving substrate <NUM> may be modified to a smaller extent by modifying the speed of either forward or backward movements 110A, 110B respectively, while maintain the direction of movement. Different line spacing may be applied in different regions of wafers <NUM>, e.g., by modifying movement speed <NUM> and/or by reversing the movement direction if needed.

Advantageously, dynamic pattern transfer printing system <NUM> enables accurate matching of the positions of the printed fingers to the pattern of SE lines on the silicon wafer during printing, as disclosed herein. For example, by moving and/or by modifying the speed <NUM> by which controller <NUM> moves receiving substrate <NUM>, more accurate deposition of paste <NUM> from tranches <NUM> onto the predefined locations on receiving substrate <NUM> may be achieved.

In certain embodiments, different line spacing may be applied in different regions of wafers <NUM>, e.g., by modifying movement speed <NUM> and/or by reversing the movement direction if needed. For example, a first pattern <NUM> of trenches <NUM> on source substrate <NUM> may have a first unform pitch p<NUM> and second pattern <NUM> of deposited paste on receiving substrate <NUM> may comprise a plurality of linear positions (like SE lines) distributed over the CMD with a variable pitch. Controller <NUM> may be configured to move moveable stage <NUM> with a pre-defined variable speed along direction 110A or 110B thus to ensure that all the lines printed from the source substrate <NUM> are deposited exactly on the specified linear locations on the receiving substrate <NUM>.

<FIG> is a high-level schematic illustration of modifications of the transferred pattern by dynamic pattern transfer printing system <NUM> according to wafer width, according to some embodiments of the invention. In certain embodiments, controller <NUM> may be further configured to calculate second pitch p<NUM> with respect to first pitch p<NUM> according to a relation between widths ws and wR of source substrate <NUM> and receiving substrate <NUM>, respectively. Dynamic pattern transfer printing system <NUM> may be configured to start deposition by aligning source substrate <NUM> have the first trench located exactly opposite to the pre-defined first finger location on receiving substrate <NUM> and scanning trench pattern <NUM> by laser beam <NUM> sequentially from the first trench to the last trench of pattern <NUM>, while moving receiving substrate <NUM> during printing in a direction and with a speed required for depositing the paste from trenches <NUM> onto receiving substrate <NUM> so that the last printed line is located on the pre-defined distance from the first printed line (which is different from the distance between the first trench to the last trench on source substrate <NUM>).

For example, assuming that the number of trenches <NUM> is equal to the number of printed lines <NUM>, with stage speed <NUM> denoted as v (e.g., vF or vB) and denoting the scanner speed <NUM> across trenches <NUM> (CMD) as vS, the width of source substrate <NUM> as wS and the width of receiving substrate <NUM> as wR, may be approximately estimated as wR/wS=(vS±vF/B)/vS, or vF/B=±vS·(wR/wS-<NUM>), being positive for vF (when receiving substrate <NUM> is narrower than source substrate <NUM>) and negative for vB (when receiving substrate <NUM> is wider than source substrate <NUM>).

Advantageously, this mode of operation may be especially useful for printing conducting lines (fingers) on crystalline silicon PV cells (wafers), when the size of the silicon wafer is different from the width of the polymer tape roll that is used as source substrate <NUM> and is restricted by the tape manufacturing equipment. Dynamic pattern transfer printing system <NUM> thus enables to print fingers from tape having a certain width onto silicon wafer of different sizes. For example, typical tape width is defined and manufactured for pattern transfer printing on a stationary wafer of ws=<NUM> size. The same tape width may be used for PTP on wafers of wR=<NUM> size. In this case only length of the trenches is increased, which does not require any change in the equipment for the pattern tape manufacturing. For spreading the printed lines over a wafer of larger width the dynamic printing with <NUM> wafer movement during printing may applied, with a corresponding backward movement 110B of receiving substrate <NUM> during paste transfer (in this non-limiting example, vB could be estimated as approximately <NUM>/<NUM> of vs, the exact value further depending on process details).

<FIG> is a high-level schematic illustration of source substrate <NUM> and stage movements <NUM> for one-to-many paste deposition, according to some embodiments of the invention. Dynamic pattern transfer printing system <NUM> may be configured to deposit paste <NUM> from one source substrate <NUM> onto a plurality of receiving substrates <NUM>, with first pattern <NUM> of trenches <NUM> on source substrate <NUM> comprising a plurality of groups <NUM> of trenches <NUM>, and controller <NUM> being further configured to deposit paste <NUM> from trenches <NUM> of each group <NUM> onto one of receiving substrates <NUM>, and to switch receiving substrate <NUM> between consecutive groups <NUM> of trenches <NUM>.

Groups <NUM> may be separated by specified distances d (equal or variable, illustrated schematically as gaps <NUM>), e.g., with each group having trenches <NUM> arranged at one or more pitches p<NUM> (illustrated in a non-limiting manner as being equal among groups <NUM>, but possibly variable as well). Dynamic pattern transfer printing system <NUM> and/or controller <NUM> may be configured to position each consecutive receiving substrate <NUM> for receiving paste <NUM> from trenches <NUM> of respective consecutive groups <NUM> on source substrate <NUM> at specified receiving pitch(es) p<NUM> (not shown), in a close proximity to source substrate <NUM>, in such a way that the first trench of each consecutive group <NUM> is located exactly opposite to the first pre-defined printed line location on respective consecutive receiving substrate <NUM>. While the optical head of laser scanner <NUM> of dynamic pattern transfer printing system <NUM> is used to scan trench pattern <NUM> (in direction <NUM> along trenches <NUM> and consecutively along scanning direction <NUM> perpendicular to trenches <NUM>) sequentially from the first trench to the last trench of each group <NUM>, controller <NUM> is configured (i) to move respective receiving wafer <NUM> continuously in a direction 110B against scanning direction <NUM> of laser scanner optical head <NUM> and with a speed vF, which transforms source pitch p<NUM> to receiving pitch p<NUM> as disclosed above and (ii) to switch receiving substrates <NUM> (e.g., by removing previous wafer and providing the consecutive wafer), locate and set the first pre-defined printed line position on receiving substrate <NUM> opposite to the first trench of next group <NUM> of trenches <NUM> on source substrate <NUM> and commence scanning and transferring paste <NUM> from consecutive group <NUM> to consecutive receiving substrate <NUM>. Switching receiving substrates <NUM> may be carried out, e.g., during the movement of laser scanner optical head <NUM> over gap <NUM> thus keeping the scanner head speed substantially constant.

In certain embodiments, dynamic pattern transfer printing system <NUM> may thus be configured to print conducting lines (fingers) on crystalline silicon PV cells (wafers) in high volume manufacturing, reaching high throughput that may possibly be limited only by the printing equipment itself. Source substrate <NUM> (a polymer tape segment) may comprise much more trenches <NUM> (more densely arranged) than the required number of printed lines on the wafer as receiving substrate <NUM>, and be used to print multiple wafers. For example, if the number of fingers per wafer is <NUM>, the number of trenches <NUM> on the tape segment may be <NUM>, with receiving pitch p<NUM> being ten times greater than source pitch p<NUM> - it may be possible to print ten wafers (as receiving substrates <NUM>) from one tape segment (as source substrate <NUM>) continuously in one movement of laser scanner optical head <NUM> along scanning direction <NUM>. When the dynamic printing is operated, it is possible to locate the next wafer exactly at the required position at the beginning of the next filled group <NUM> of trenches <NUM> on source substrate <NUM> to ensure continuous movement of wafers <NUM> through printing system <NUM>. High throughput printing is enabled by arranging trenches <NUM> on tape segment <NUM> at much smaller pitch p<NUM> than the required pitch p<NUM> of fingers printed on wafer <NUM>. For example, a typical pitch p<NUM> of fingers on receiving substrate <NUM> (e.g., PV wafer) may be within <NUM>-<NUM> (e.g., <NUM>-<NUM>, <NUM>-<NUM>, or any other intermediate range) while a typical pitch p<NUM> of trenches <NUM> on source substrate <NUM> (e.g., polymer tape) may be about <NUM>-<NUM> (e.g., <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> or any other intermediate range). Therefore, in one continuous movement of laser scanner optical head <NUM> it is possible to print up to ten wafers <NUM>, or possible up to five wafers <NUM>, up to <NUM> wafers <NUM>, or even up to <NUM> or <NUM> wafers <NUM>, or intermediate values, depending on the exact configuration. After all trenches <NUM> from tape segment <NUM> are printed, printing system <NUM> may move another tape segment <NUM> with trenches <NUM> filled by paste <NUM> to the printing station while laser scanner optical head <NUM> returns to its initial position. At this time of segment replacement and scanner head coming back to its starting position (first trench <NUM> of first group <NUM> of trenches on source substrate <NUM>), next wafer <NUM> may be moved with lower speed to the start position, and when reaching it, the process of continuous printing with high wafer speed and high wafer throughput may continue. Since each wafer <NUM> is printed with one group <NUM> of trenches <NUM> separated with small pitch p<NUM> on tape segment <NUM>, the speed of laser scanner optical head <NUM> along scanning direction <NUM> (CMD) is relatively low. For example, if one hundred fingers are printed per wafer <NUM> during about <NUM> seconds from tape <NUM> with pitch p<NUM> of <NUM>, the speed of scanner head <NUM> is <NUM>/sec. Such relatively low speed enables very accurate control of positioning laser beam <NUM> relative to trenches <NUM>.

A pattern transfer sheet <NUM> used as source substrate <NUM>, comprises multiple groups of trenches <NUM> and is configured to receive printing paste <NUM> and release printing paste <NUM> from trenches <NUM> upon illumination by laser beam <NUM> onto receiving substrate <NUM>, wherein pitch p<NUM> of trenches <NUM> in each group <NUM> is constant and groups <NUM> are separated by gaps <NUM>, as illustrated in <FIG>, with a schematic cross section of pattern transfer sheet <NUM> illustrated in <FIG>.

In various embodiments, pitches p<NUM> in all groups <NUM> may be equal. In various embodiments, pitches p<NUM> may be between <NUM>-<NUM>.

In various embodiments, gaps <NUM> between all consecutive groups <NUM> may be equal. Pattern transfer sheet <NUM> may be configured to have gaps <NUM> correspond to scanning speed vS of pattern transfer sheet <NUM> by laser scanner optical head <NUM> (e.g., in printing system <NUM>) multiplied by the duration required to switch and position receiving substrate <NUM> between consecutive pattern transfers, as explained herein. For example, gaps <NUM> may be between <NUM>-<NUM>, e.g., up to <NUM>, up to <NUM>, up to <NUM> or up to <NUM>.

In various embodiments, printing system <NUM> may be configured, e.g., through the control of movements <NUM>, to increase the accuracy of paste deposition <NUM> from trenches <NUM>, e.g., to improve the accuracy of produced PV cells. For example, printing system <NUM> may be configured, e.g., through the control of movements <NUM>, to increase the accuracy of selective emitter pre-alignment, e.g., by increasing the accuracy of paste deposition on PV selective emitter lines.

<FIG> is a high-level block diagram of exemplary controllers <NUM>, which may be used with embodiments of the present invention. Controller(s) <NUM> may include one or more controller or processor <NUM> that may be or include, for example, one or more central processing unit processor(s) (CPU), one or more Graphics Processing Unit(s) (GPU or general-purpose GPU - GPGPU), a chip or any suitable computing or computational device, an operating system <NUM>, a memory <NUM>, a storage <NUM>, input devices <NUM> and output devices <NUM>.

Operating system <NUM> may be or may include any code segment designed and/or configured to perform tasks involving coordination, scheduling, arbitration, supervising, controlling, or otherwise managing operation of controller(s) <NUM>, for example, scheduling execution of programs. Memory <NUM> may be or may include, for example, a Random-Access Memory (RAM), a read only memory (ROM), a Dynamic RAM (DRAM), a Synchronous DRAM (SD-RAM), a double data rate (DDR) memory chip, a Flash memory, a volatile memory, a non-volatile memory, a cache memory, a buffer, a short-term memory unit, a long-term memory unit, or other suitable memory units or storage units. Memory <NUM> may be or may include a plurality of possibly different memory units. Memory <NUM> may store for example, instructions to carry out a method (e.g., code <NUM>), and/or data such as user responses, interruptions, etc..

Executable code <NUM> may be any executable code, e.g., an application, a program, a process, task or script. Executable code <NUM> may be executed by controller <NUM> possibly under control of operating system <NUM>. For example, executable code <NUM> may when executed cause the production or compilation of computer code, or application execution such as VR execution or inference, according to embodiments of the present invention. Executable code <NUM> may be code produced by methods described herein. For the various modules and functions described herein, one or more computing devices and/or components of controller(s) <NUM> may be used. Devices that include components similar or different to those included in controller(s) <NUM> may be used and may be connected to a network and used as a system. One or more processor(s) <NUM> may be configured to carry out embodiments of the present invention by for example executing software or code.

Storage <NUM> may be or may include, for example, a hard disk drive, a floppy disk drive, a Compact Disk (CD) drive, a CD-Recordable (CD-R) drive, a universal serial bus (USB) device or other suitable removable and/or fixed storage unit. Data such as instructions, code, VR model data, parameters, etc. may be stored in a storage <NUM> and may be loaded from storage <NUM> into a memory <NUM> where it may be processed by controller <NUM>. In some embodiments, some of the components shown in Figure <NUM> may be omitted.

Input devices <NUM> may be or may include for example a mouse, a keyboard, a touch screen or pad or any suitable input device. It will be recognized that any suitable number of input devices may be operatively connected to controller(s) <NUM> as shown by block <NUM>. Output devices <NUM> may include one or more displays, speakers and/or any other suitable output devices. It will be recognized that any suitable number of output devices may be operatively connected to controller(s) <NUM> as shown by block <NUM>. Any applicable input/output (I/O) devices may be connected to controller(s) <NUM>, for example, a wired or wireless network interface card (NIC), a modem, printer or facsimile machine, a universal serial bus (USB) device or external hard drive may be included in input devices <NUM> and/or output devices <NUM>.

According to the invention, a computer program product comprising a non-transitory computer readable storage medium having computer readable program embodied therewith is provided, the computer readable program configured to carry out the dynamic pattern transfer printing method disclosed herein. Embodiments of the invention may include one or more article(s) (e.g., memory <NUM> or storage <NUM>) such as a computer or processor non-transitory readable medium, or a computer or processor non-transitory storage medium, such as for example a memory, a disk drive, or a USB flash memory, encoding, including or storing instructions, e.g., computer-executable instructions, which, when executed by a processor or controller, carry out methods disclosed herein.

<FIG> is a high-level flowchart illustrating a dynamic pattern transfer printing method <NUM>, according to some embodiments of the invention. The method stages may be carried out with respect to system <NUM> described above, which may optionally be configured to implement method <NUM>. Method <NUM> may be at least partially implemented by at least one computer processor, e.g., in controller <NUM>. Certain embodiments comprise computer program products comprising a computer readable storage medium having computer readable program embodied therewith and configured to carry out the relevant stages of method <NUM>. Method <NUM> may comprise the following stages, irrespective of their order.

Dynamic pattern transfer printing method <NUM> may comprise transferring a paste pattern from a source substrate to a receiving substrate, by illuminating across the paste pattern at a scanning direction (stage <NUM>). The illuminated source substrate comprises a plurality of trenches arranged in a first pattern and holding printing paste and is configured to release the printing paste from the trenches and onto a receiving substrate upon the illumination by a laser beam, which is carried out along the trenches, and at a scanning direction across the trenches. Method <NUM> may further comprise controllably moving the receiving substrate to yield a second pattern of deposited paste on the receiving substrate, which is different from the first pattern of trenches on the source substrate (stage <NUM>).

In some embodiments, the first pattern of trenches on the source substrate may have a first pitch and the second pattern of deposited paste on the receiving substrate may have a second pitch. When the first pitch is larger than the second pitch, the controlled movement may be carried out along the scanning direction at a forward speed set to decrease the pitch of the pattern (stage <NUM>), while when the first pitch is smaller than the second pitch, the controlled movement may be carried out against (in a contrary direction to) the scanning direction at a backward speed set to increase the pitch of the pattern (stage <NUM>). Method <NUM> may further comprise calculating the pattern pitch on the receiving substrate with respect to the paste pattern pitch according to the relation between the widths of the source substrate and the receiving substrate (stage <NUM>) and control the pattern transfer process accordingly.

In certain embodiments, the first pattern of trenches on the source substrate may comprise a plurality of groups of the trenches, and method <NUM> may further comprise depositing paste from one source substrate onto a plurality of receiving substrates by depositing the paste from the trenches of each group onto one of the receiving substrates, and switching the receiving substrate between consecutive groups of the trenches (stage <NUM>). The receiving substrates (e.g., wafers) may be consecutively-switched to enable continues pattern transfer onto them from the single source substrate (per group of wafers).

Claim 1:
A dynamic pattern transfer printing system (<NUM>) comprising:
at least one laser scanner (<NUM>) configured to illuminate with at least one laser beam (<NUM>) a source substrate (<NUM>) that comprises a plurality of trenches (<NUM>) arranged in a first pattern (<NUM>) and holding printing paste (<NUM>), wherein the source substrate (<NUM>) is configured to release the printing paste from the trenches and onto a receiving substrate (<NUM>) upon the illumination by the laser beam,
a moveable stage (<NUM>) supporting the receiving substrate, wherein the receiving substrate (<NUM>) is affixed to the moveable stage during the releasing of the printing paste from the source substrate, and
a controller (<NUM>) configured to control the laser beam illumination along the trenches, and at a scanning direction (<NUM>) across the trenches, characterised in that the controller is further configured to move the moveable stage (<NUM>) to yield a second pattern (<NUM>) of deposited paste on the receiving substrate, which is different from the first pattern (<NUM>) of trenches on the source substrate wherein the first pattern (<NUM>) of trenches on the source substrate (<NUM>) has a first pitch (p<NUM>) and the second pattern (<NUM>) of deposited paste on the receiving substrate (<NUM>) has a second pitch (p<NUM>) and wherein the controller (<NUM>) is configured to move the moveable stage (<NUM>) in at least one of:
the scanning direction (<NUM>), to yield the second pattern (<NUM>) on the receiving substrate, wherein the first pitch (p<NUM>), the second pitch (p<NUM>), a forward speed of the moveable stage (vF) and a scanner speed across the trenches (vS) are configured to have the relation p<NUM>=p<NUM>·(vS-vF)/vS to make the second pitch smaller than the first pitch (p<NUM><p<NUM>); and/or
against the scanning direction (<NUM>), to yield the second pattern (<NUM>) on the receiving substrate, wherein the first pitch (p<NUM>), the second pitch (p<NUM>), a backward speed of the moveable stage (vB) and a scanner speed across the trenches (vS) are configured to have the relation p<NUM>=p<NUM>·(vS+vB)/vS to make the second pitch larger than the first pitch (p<NUM>>p<NUM>).