CN114068772B

CN114068772B - Selectively switchable photomask and system for processing micro light emitting diodes

Info

Publication number: CN114068772B
Application number: CN202111293031.7A
Authority: CN
Inventors: 李冠谊; 郭建宏; 陈韦洁; 曾文贤
Original assignee: AU Optronics Corp
Current assignee: AU Optronics Corp
Priority date: 2021-05-06
Filing date: 2021-11-03
Publication date: 2023-06-02
Anticipated expiration: 2041-11-03
Also published as: CN114068772A; TW202244992A; TWI759198B

Abstract

The invention discloses a selective switching photomask for a laser light source and a system for processing a miniature light emitting diode, wherein the selective switching photomask comprises a switching unit arranged under the laser light source. The switching unit comprises a first substrate, a second substrate opposite to the first substrate, a pixel electrode, a common electrode and a switchable light penetration layer. The pixel electrode is disposed on the first substrate. The common electrode is arranged on the second substrate. The switchable light penetration layer is arranged between the pixel electrode and the common electrode.

Description

Selectively switchable photomask and system for processing micro light emitting diodes

Technical Field

The present invention relates to a selectively switchable photomask for use with a laser light source, and more particularly to a selectively switchable photomask for use with a micro light emitting diode.

Background

With continued progress in panel technology, micro light emitting diodes (micro light emitting diode; micro LEDs) may be applied to various displays, such as borderless displays, notebook computer displays, wearable displays, and the like. Although micro LEDs have advantages of high brightness, short reaction time, high luminous efficacy, etc., the assembly of micro LEDs still faces problems of low production efficiency, high manufacturing cost, etc.

In view of the foregoing, there is a need to develop a new method of assembling micro LEDs to overcome the foregoing problems.

Disclosure of Invention

The invention provides a selective switching photomask for a laser light source, which comprises a switching unit arranged below the laser light source. The switching unit comprises a first substrate, a second substrate opposite to the first substrate, a thin film transistor element, a common electrode and a switchable light penetration layer. The pixel electrode is disposed on the first substrate. The common electrode is arranged on the second substrate. The switchable light penetration layer is arranged between the pixel electrode and the common electrode.

In some embodiments, the switchable light transmissive layer is a liquid crystal layer.

In some embodiments, the switching unit provides a penetration rate of less than about 30%.

In some embodiments, the switching unit provides a penetration rate of about 30% to about 80%.

In some embodiments, the switching unit provides a penetration rate of about 80% to about 100%.

In some embodiments, the selectively switchable photomask further comprises a light shielding element disposed between the second substrate and the electrode, wherein the light shielding element has a first projection on the first substrate, the pixel electrode has a second projection on the first substrate, and the first projection and the second projection are staggered.

In some embodiments, the selectively switchable photomask further comprises a light shielding element disposed on the second substrate, wherein the light shielding element has a first projection on the first substrate, the pixel electrode has a second projection on the first substrate, and the first projection and the second projection are staggered.

In some embodiments, the selectively switchable photomask further comprises a thin film transistor element and a light blocking element. The thin film transistor element is arranged on the first substrate and separated from the pixel electrode. The shading element is arranged on the thin film transistor element, wherein the shading element is provided with a first projection on the first substrate, the pixel electrode is provided with a second projection on the first substrate, and the first projection and the second projection are arranged in a staggered mode.

In some embodiments, the switchable light transmissive layer is an electrochromic layer.

In some embodiments, the switching unit provides a penetration rate of less than about 20%.

In some embodiments, the switching unit provides a penetration rate of about 20% to about 60%.

In some embodiments, the switching unit provides a penetration rate of about 60% to about 80%.

The invention provides a system for processing micro light emitting diodes, comprising a selectively switchable photomask and a carrier substrate arranged below the selectively switchable photomask.

In some embodiments, the system for processing micro light emitting diodes further comprises an adhesive layer disposed under and in contact with the carrier substrate.

In some embodiments, the system for processing micro light emitting diodes further comprises a movable mask disposed between the switching unit and the carrier substrate, the movable mask having a plurality of apertures separated from each other, wherein the pixel electrode has a first projection on the first substrate, each of the plurality of apertures has a second projection on the first substrate, the first projection is larger than the second projection, and the second projection is located in the first projection.

The invention provides a system for processing a micro light emitting diode, which comprises a selectively switchable photomask and an adhesive layer, wherein the adhesive layer is arranged under the selectively switchable photomask and is in direct contact with a first substrate of the selectively switchable photomask.

The following description will make detailed description of the above description in terms of embodiments, and provide further explanation of the technical solution of the present invention.

Drawings

The detailed description of the present invention will be fully understood when read in conjunction with the accompanying drawings. It should be noted that, in accordance with industry standard practice, the features are not drawn to scale and are for illustration purposes only. In fact, the dimensions of the various features may be arbitrarily increased or decreased for clarity of discussion.

FIG. 1 is a schematic cross-sectional view of a macro-transfer apparatus according to some embodiments of the present invention;

FIG. 2 is a schematic cross-sectional view of a laser bonding apparatus according to some embodiments of the present invention;

FIG. 3 is a schematic perspective view of a macro-transfer apparatus according to some embodiments of the present invention;

FIG. 4 is a circuit diagram of a selectively switchable photomask according to some embodiments of the present invention;

FIGS. 5-7 are schematic cross-sectional views of selectively switchable photomasks according to some embodiments of the present invention;

FIG. 8 is a circuit diagram of a selectively switchable photomask according to some embodiments of the present invention;

FIG. 9 is a schematic cross-sectional view of a selectively switchable photomask according to some embodiments of the present invention;

FIGS. 10A, 10B and 10C are schematic perspective views of a macro-transfer device according to some embodiments of the present invention;

FIG. 11 is a schematic cross-sectional view of the macro-transfer device of FIG. 10A according to some embodiments of the present invention;

fig. 12 is a schematic perspective view of a macro-transfer apparatus according to some embodiments of the present invention.

Symbol description

100 selectively switchable photomask

100A selectively switchable photomask

100B selectively switchable photomask

100C selectively switchable photomask

100D selectively switchable photomask

100E selectively switchable photomask

102 switching unit

102a switching unit

102b switching unit

102c switching unit

110 laser light source

112 laser light

114 laser light

120R carrier substrate

120G carrier substrate

120B carrier substrate

122R adhesive layer

122G adhesive layer

122B adhesive layer

130R:micro LED

130G:micro LED

130B:micro LED

140 carrier substrate

142 adhesive layer

150:thin film transistor substrate

510 first substrate

520 thin film transistor element

522 grid electrode

523 first metal layer

524 gate insulation layer

526. Channel layer

528 source/drain

529 second metal layer

530 passivation film

540 pixel electrode

550 second substrate

560 common electrode

570 shading element

580 switchable light transmissive layer

582a liquid Crystal molecule

582b liquid Crystal molecule

590 spacer

920 control element

922 second metal layer

924 passivation film

926 pixel electrode

930 switchable light transmissive layer

932 electrochromic film

934 electrolyte

936 ion storage conductor film

1000 removable mask

1010 holes

R region

P1:projection of

P2:projection of

P3:projection of

P4:projection of

P5:projection of

X direction

Z direction

Detailed Description

For a more complete and thorough description of the present invention, reference is made to the accompanying drawings and the various embodiments described below, wherein like reference numbers represent the same or similar elements.

Various embodiments of the invention are disclosed in the accompanying drawings, and for purposes of explanation, numerous practical details are set forth in the following description. However, it should be understood that these practical details are not to be taken as limiting the invention. That is, in some embodiments of the invention, these practical details are unnecessary. Furthermore, for the sake of simplicity of the drawing, some of the well-known structures and elements are shown in the accompanying drawings in a simplified schematic manner.

In this document, a range from "one value to another value" is a shorthand way of referring individually to all the values in the range, which are avoided in the specification. Thus, recitation of a particular numerical range includes any numerical value within that range, as well as the smaller numerical range bounded by any numerical value within that range, as if the any numerical value and the smaller numerical range were written in the specification in the clear.

In the description and claims, unless the context clearly dictates otherwise, the terms "a" and "an" may refer to either a single or a plurality of. The terms "about," "approximately," or "approximately" as used herein generally refer to an error or range of values of the index that is within about twenty percent, preferably within about ten percent, and more preferably within about five percent.

The micro light emitting diode (micro light emitting diode; micro LED) display is composed of an array of micro light emitting diodes (micro LED array). In general, the micro LEDs are micro LEDs that can emit light of various colors (e.g., red, green, blue, or other colors), and a plurality of micro LEDs are combined and arranged to form a micro LED array. The process of forming the micro LED array includes a mass transfer operation of transferring the micro LEDs to the carrier substrate and a bonding operation of bonding the micro LEDs to the thin film transistor substrate.

The present invention provides a selectively switchable photomask that can be used for bulk transfer operations as well as bonding operations. When the huge transfer operation is carried out, the selective switching photomask is arranged under the laser light source, so that a large number of micro LEDs can be transferred onto the carrier substrate, and the production efficiency is improved. When the bonding operation is performed, the selectively switchable photomask is arranged below the laser light source, so that a large number of micro LEDs can be bonded to the thin film transistor substrate, and the production efficiency is improved. Because the selective switching photomask of the invention can be simultaneously applied to mass transfer and bonding operations, the manufacturing cost can be greatly reduced, and the overall production efficiency can be further improved. Various embodiments of the selectively switchable photomask of the present invention will be described in detail below.

Referring to fig. 1, a schematic cross-sectional view of a macro-transfer apparatus according to some embodiments of the invention is shown. Bulk transfer may also be referred to as selective laser transfer, and in particular, the micro LEDs to be transferred are selectively transferred onto a carrier substrate by a laser 112. As shown in fig. 1, the selectively switchable photomask 100 is disposed under a laser light source 110 that provides laser light 112, a carrier substrate 120B fixes micro LEDs 130B on the adhesive layer 122B through an adhesive layer 122B, and a carrier substrate 140 fixes

micro LEDs

130R, 130G, 130B on the carrier substrate 140 through an adhesive layer 142, respectively. It should be noted that fig. 1 shows that the transfer of the

micro LEDs

130R, 130G is completed before the transfer of the micro LED130B is completed. In performing the mass transfer operation, the laser 112 passes through the switching unit 102a and the carrier substrate 120B to the adhesive layer 122B, and the adhesive layer 122B changes its adhesive force due to the energy of the laser 112, so that the micro LED130B originally fixed on the carrier substrate 120B falls off onto the carrier substrate 140 and is fixed by the adhesive layer 142 on the carrier substrate 140. The

micro LEDs

130R, 130G, 130B in fig. 1 undergo the above-described transfer operation, respectively, to form carrier substrates 140 carrying the

micro LEDs

130R, 130G, 130B. Note that, the micro LED 130R in this case represents a red micro LED, the micro LED 130G represents a green micro LED, and the micro LED130B represents a blue micro LED. Similarly, the carrier substrate 120B and the adhesive layer 122B represent the carrier substrate and the adhesive layer carrying blue micro LEDs.

In some embodiments, the laser source 110May be a titanium sapphire laser, which may have a broad wavelength tuning range (e.g., wavelengths between about 670nm and about 1200 nm). In other embodiments, the laser source 110 may be a rare earth doped glass (SiO ₂ ) Fiber lasers with optical fibers as gain media. In some embodiments, the laser 112 may be Nd YAG, nd YVO ₄ Or Yb, which can provide peak wavelengths (peak wavelength) of about 266nm, 355nm, 532nm, but is not limited thereto. In other embodiments, the laser 112 may be a gaseous laser, such as providing about 248nm KrF, about 353nm XeF, about 193nm ArF, about 308nm XeCl, about 157nm F ₂ An excimer laser of (a); it may also be, for example, but not limited to, a helium neon laser providing about 632.8nm, a carbon dioxide laser providing about 1064nm, a carbon monoxide laser providing about 6000nm to about 8000nm, a nitrogen laser providing about 337.1nm, a helium cadmium laser providing about 442nm, a metal vapor laser, a metal halide laser, or a mixed gas laser.

It should be noted that the light transmission capability of the switching

units

102a and 102b of the selectively switchable photomask 100 can be changed by adjustment. In other words, the laser light 112 shown in fig. 1 can pass through the switching unit 102a but cannot pass through the switching unit 102b. Thus, mass transfer may also be referred to as selective laser transfer. Further, in some embodiments, the bulk transfer may selectively transfer the micro LED 130R onto the carrier substrate 140 first, then the micro LED 130G onto the carrier substrate 140, and finally the micro LED130B onto the carrier substrate 140. The micro LED arrays are formed by combining and arranging a plurality of

micro LEDs

130R, 130G, 130B by a mass transfer device as shown in fig. 1.

Fig. 2 is a schematic cross-sectional view of a laser bonding apparatus according to some embodiments of the invention. In detail, after the mass transfer operation shown in fig. 1 is completed, the laser joining operation shown in fig. 2 is performed. The selectively switchable photomask 100 is placed under the laser light source 110 that provides the laser light 114 and the carrier substrate 140 in fig. 1 is flipped (e.g., rotated 180 degrees) so that the

micro LEDs

130R, 130G, 130B are oriented toward the thin film transistor substrate 150. Similarly, in performing the laser bonding operation, the laser 114 passes through the switching unit 102a, the carrier substrate 140, the adhesive layer 142, and the

micro LEDs

130R, 130G, 130B, so that the pads (e.g., tin pads) on the

micro LEDs

130R, 130G, 130B are melted and bonded on the thin film transistor substrate 150.

Referring to fig. 1 and fig. 3, fig. 3 is a schematic perspective view of a mass transfer device according to some embodiments of the invention. In detail, fig. 3 is a schematic perspective view of fig. 1. For clarity of illustration, some elements in fig. 1 are not shown in fig. 3, and the micro LED in fig. 1 is shown in fig. 3 as a simplified cuboid.

Referring to fig. 4, fig. 4 is a circuit diagram of a selectively switchable photomask 100 according to some embodiments of the present invention. The selectively switchable photomask 100 includes a plurality of switching units 102 and wirings arranged in an array, wherein the switching units 102 include switching

units

102a, 102b, 102c. It should be noted that, in the present embodiment, the switching units 102a through which the

lasers

112 and 114 can pass are shown as a cuboid without dots, the switching units 102b through which the

lasers

112 and 114 cannot pass are shown as a cuboid with dense dots (like black), and the switching units 102c through which the

lasers

112 and 114 can partially pass are shown as a cuboid with sparse dots (like gray). Various alternative embodiments of the selectively switchable photomask 100 are described in detail below with reference to the accompanying drawings.

Fig. 5-7 are schematic cross-sectional views of selectively switchable photomasks according to some embodiments of the present invention. In detail, fig. 5 to 7 are schematic cross-sectional views of the selectively switchable photomask of the region R of fig. 4. The region R includes the switching unit 102a on the left side and the switching unit 102b on the right side. It should be appreciated that some elements in fig. 4 are not shown in fig. 5-7 (e.g., wiring) for simplicity of the drawing.

Referring to fig. 5, a schematic cross-sectional view of a selectively switchable photomask 100A according to some embodiments of the present invention is shown. The selectively switchable photomask 100A includes a switching unit 102a on the left side and a switching unit 102b on the right side. The selectively switchable photomask 100A includes a first substrate 510, a thin film transistor element 520, a passivation film 530, a pixel electrode 540, a second substrate 550, a common electrode 560, a light shielding element 570, a switchable light transmissive layer 580, and a spacer 590. The first substrate 510 and the second substrate 550 are disposed opposite to each other, and a thin film transistor element 520, a passivation film 530, a pixel electrode 540, a common electrode 560, a light shielding element 570, a switchable light transmissive layer 580, and a spacer 590 are disposed between the first substrate 510 and the second substrate 550.

As shown in fig. 5, the thin film transistor element 520 is disposed on the first substrate 510, and the thin film transistor element 520 includes a gate 522, source/drain 528, a channel layer 526, and a gate insulating layer 524 between the channel layer 526 and the gate 522. The passivation film 530 is disposed on the thin film transistor element 520. In detail, the passivation film 530 covers upper surfaces and/or sidewalls of the channel layer 526, the source/drain electrodes 528, and the gate insulating layer 524. The gate insulating layer 524 extends along above the first substrate 510 and continuously spans the switching

cells

102a and 102b. The passivation film 530 extends along above the gate insulating layer 524 and continuously spans the switching

cells

102a and 102b. Selectively switchable photomask 100A also includes first metal layer 523 and second metal layer 529. The first metal layer 523 is electrically connected to the gate 522, and the second metal layer 529 is electrically connected to the source/drain 528. In some embodiments, the gate 522 and/or the source/drain 528 may be a single layer structure composed of aluminum (Al), silver (Ag), copper (Cu), molybdenum (Mo), chromium (Cr), titanium (Ti), tantalum (Ta), or an alloy thereof. In other embodiments, the gate 522 and/or source/drain 528 may be a multi-layer structure, such as Cu/Mo, al/Nd, mo/W, mo/Cu/Mo, mo/Al/Mo, ti/Cu/Ti, ti/Al/Ti. In some embodiments, the gate 522 and/or source/drain 528 have a thickness (in direction X) of between about 0.3 μm and about 1.0 μm, e.g., 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 μm. In some embodiments, the channel layer 526 may be an amorphous silicon layer or an amorphous silicon layer doped with an N-type dopant and have a thickness between about 0.1 μm and about 0.2 μm, such as 0.125, 0.15, 0.175 μm. In some embodiments, the gate insulating layer 524 may be made of silicon nitride (SiN _x ) Or silicon oxide (SiO) _x ) And has a thickness of between about 0.1 μm and about 0.3 μm, e.g., 0.15, 0.2, 0.25 μm. In some embodiments of the present invention, in some embodiments,the passivation film 530 may be made of silicon nitride (SiN) _x ) And has a thickness of between about 0.1 μm and about 0.3 μm, e.g., 0.15, 0.2, 0.25 μm.

As shown in fig. 5, the pixel electrodes 540 are disposed on the passivation film 530, and each pixel electrode 540 is connected to a corresponding one of the thin film transistor elements 520. The common electrode 560 is disposed on the second substrate 550, and extends along above the second substrate 550 and continuously spans the switching

units

102a and 102b. In some embodiments, the pixel electrode 540 and/or the common electrode 560 may be composed of Indium Tin Oxide (ITO) or indium zinc oxide (indium zinc oxide; IZO) and have a thickness of between about 0.04 μm and about 0.2 μm, for example, 0.05, 0.08, 0.1, 0.12, 0.15, 0.18 μm. In some embodiments, the pixel electrode 540 and the common electrode 560 may have the same thickness, whereas in other embodiments, the pixel electrode 540 and the common electrode 560 may have different thicknesses.

The light shielding element 570 is disposed on the second substrate 550 and between the second substrate 550 and the common electrode 560, wherein the light shielding element 570 has a projection P1 on the first substrate 510, and the pixel electrode 540 has a projection P2 on the first substrate 510, and the projections P1 and P2 are staggered. In detail, the light shielding element 570 is disposed above the thin film transistor element 520 in the direction Z, so that the light shielding element 570 can protect the thin film transistor element 520 from being damaged when the selectively switchable photomask 100A is irradiated by the

laser light

112, 114 from above. It should be noted that the light shielding element 570 of fig. 5 is shown to cover the width of the source/drain electrode 528, however, a larger width light shielding element 570 is also included in the embodiment of the present invention, such as the width of the entire tft element 520. The shading elements 570 may also be referred to as Black Matrix (BM) which may have a patterned matrix to form an array like that shown in fig. 4. In some embodiments, the light shielding element 570 may be composed of a black resin, comprising resin, carbon, photoinitiator, solvent, additives (e.g., additive accelerators, cure accelerators, and/or surfactants), or other similar materials, and have a thickness of between about 1 μm and about 3 μm, e.g., 1.5, 2, 2.5 μm.

The switchable light transmissive layer 580 is disposed between the first substrate 510 and the second substrate 550. In detail, the switchable light transmissive layer 580 is disposed between the pixel electrode 540 and the common electrode 560. In some embodiments the switchable light transmissive layer 580 is a liquid crystal layer, wherein the liquid crystal layer comprises

liquid crystal molecules

582a, 582b. In some embodiments, the switchable light transmissive layer 580 has a thickness of between about 2 μm and about 4 μm, such as 2.5, 3, 3.5 μm. The switching of the thin film transistor element 520 and the

liquid crystal molecules

582a, 582b in the liquid crystal layer may be controlled by an external controller (not shown). The thin film transistor element 520 is controlled to be turned on and off, and the pixel electrode 540 is charged to have a pixel voltage (V _pixel ) So that the pixel voltage is equal to the common voltage (V of the common electrode 560 _com ) Creating a pressure differential therebetween. The voltages applied by the respective pixel electrodes 540 may be controlled by the corresponding thin film transistor elements 520, so that the

liquid crystal molecules

582a, 582b in the liquid crystal layer change the tilt angles of the

liquid crystal molecules

582a, 582b in response to different levels of voltage differences, thereby controlling the transmittance in the

switching units

102a and 102b. When the liquid crystal molecules 582a are aligned, the

lasers

112, 114 may pass through the liquid crystal layer, as shown by the switching cell 102a in fig. 5.

In some embodiments, the switching unit 102a provides a penetration rate of about 80% to about 100%, e.g., about 85, 90, 95%. When the liquid crystal molecules 582b are irregularly arranged, the

laser light

112, 114 cannot pass through the liquid crystal layer, as shown by the switching unit 102b in fig. 5. In some embodiments, the switching unit 102b provides a penetration rate of less than about 30%, such as about 5, 10, 15, 20, 25%. In some embodiments, the switching unit 102c provides a penetration rate of about 30% to about 80%, e.g., about 40, 50, 60, 70%. In performing mass transfer (as described in fig. 1), the switching unit 102c may protect the

micro LEDs

130R, 130G, 130B from being irradiated with energy of the laser light 112 to destroy the performance of the

micro LEDs

130R, 130G, 130B. In performing laser bonding (as described in fig. 2), the switching unit 102c may protect the thin film transistor substrate 150 from being irradiated with energy of the laser light 114 to deteriorate the performance of the thin film transistor substrate 150.

As shown in fig. 5, a spacer 590 is disposed between the first substrate 510 and the second substrate 550. In detail, the spacer 590 is disposed between the common electrode 560 and the passivation film 530 to provide a sufficient supporting force when packaging the first substrate 510 and the second substrate 550.

Referring to both fig. 1 and 5, in some embodiments, when the selectively switchable photomask 100A of fig. 5 is used as a mass transfer device, the laser 112 may have a peak wavelength of about 193nm, 248nm, 266nm, 308nm, 353nm, 355nm, or 532 nm. In some embodiments, the laser source 110 provides a power range of about 0.1mW to about 10mW, for example 0.5, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 9mW. In some embodiments, the laser 112 may be active for a time of about 1ms to about 1fs, e.g., 1 μs, 1ns, 1ps.

Referring to both fig. 2 and 5, when the selectively switchable photomask 100A of fig. 5 is used as a laser bonding device, the laser 114 may have a peak wavelength of about 980nm, 1064nm, or 1000-1200 nm. In some embodiments, the laser source 110 provides a power range of about 1mW to about 100mW, such as 10, 20, 30, 40, 50, 60, 70, 80, 90mW. In some embodiments, the laser 114 may be active for a time of about 0.1ms to about 1s, e.g., 1ms, 10ms, 100ms.

Referring to fig. 6, a schematic cross-sectional view of a selectively switchable photomask 100B according to some embodiments of the present invention is shown. The selectively switchable photomask 100B of fig. 6 is similar in structure to the selectively switchable photomask 100A of fig. 5, except for the location of the light blocking element 570. The light shielding element 570 of the selectively switchable photomask 100B is disposed on the second substrate 550 and away from the first substrate 510, wherein the light shielding element 570 has a projection P3 on the first substrate 510, and the pixel electrode 540 has a projection P2 on the first substrate 510, and the projections P3 and P2 are staggered. It should be noted that, in fig. 6, the same or similar elements as those in fig. 5 are given the same reference numerals, and related descriptions are omitted, so that the description is omitted.

Referring to fig. 7, a schematic cross-sectional view of a selectively switchable photomask 100C according to some embodiments of the present invention is shown. The selectively switchable photomask 100C of fig. 7 is similar in structure to the selectively switchable photomask 100A of fig. 5, except for the location of the light blocking element 570. The light shielding element 570 of the selectively switchable photomask 100C is disposed on the thin film transistor element 520, wherein the light shielding element 570 has a projection P4 on the first substrate 510, and the pixel electrode 540 has a projection P2 on the first substrate 510, and the projections P4 and P2 are staggered. It should be noted that, in fig. 7, the same or similar elements as those in fig. 5 are given the same reference numerals, and related descriptions are omitted, so that the description is omitted.

Referring to fig. 8, a circuit diagram of a selectively switchable photomask 100D according to some embodiments of the present invention is shown. The selectively switchable photomask 100D includes a plurality of switching units 102 and wirings arranged in an array, wherein the switching units 102 include switching

units

lasers

112 and 114 can partially pass are shown as a cuboid with sparse dots (like gray). Various embodiments of selectively switchable photomask 100 are described in detail below with reference to the accompanying drawings.

Referring to fig. 9, a schematic cross-sectional view of a selectively switchable photomask 100D according to some embodiments of the present invention is shown. The selectively switchable photomask 100D includes a switching unit 102a on the left side and a switching unit 102b on the right side. The selectively switchable photomask 100D includes a first substrate 510, a control element 920, a switchable light-transmissive layer 930, a second substrate 550, and a common electrode 560. The first substrate 510 and the second substrate 550 are disposed opposite to each other, and a control element 920, a switchable light transmissive layer 930, and a common electrode 560 are disposed between the first substrate 510 and the second substrate 550.

As shown in fig. 9, the control element 920 is disposed on the first substrate 510, and the control element 920 includes a gate 522, a first metal layer 523, a gate insulating layer 524, a second metal layer 922, a passivation film 924, and a pixel electrode 926. The gate electrode 522 and the first metal layer 523 are disposed on the first substrate 510, the gate insulating layer 524 is disposed on the gate electrode 522, the first metal layer 523 and the first substrate 510, the second metal layer 922 is disposed on the gate insulating layer 524, the passivation film 924 is disposed on the second metal layer 922 and the gate insulating layer 524, and the pixel electrode 926 is disposed on the passivation film 924. As shown in fig. 9, the gate insulating layer 524 extends along above the first substrate 510 and continuously spans the switching

units

102a and 102b, and the passivation film 924 extends along above the gate insulating layer 524 and spans the switching

units

102a and 102b. It should be noted that, in fig. 9, the same or similar elements as those in fig. 5 are given the same reference numerals, and related descriptions are omitted, so that the description is omitted. In some embodiments, the second metal layer 922 has the same or similar features as the gate 522. In some embodiments, passivation film 924 has the same or similar characteristics as passivation film 530. The pixel electrode 926 has the same or similar characteristics as the pixel electrode 540.

With continued reference to fig. 9, the selectively switchable photomask 100D includes a switchable light-transmissive layer 930, wherein the switchable light-transmissive layer 930 is an electrochromic layer. In some embodiments, the electrochromic layer is selected from the group consisting of WO ₃ 、MoO ₃ 、Nb ₂ O ₅ 、TiO ₂ 、NiO、IrO ₂ 、C ₁₈ Fe ₇ N ₁₈ 、V ₂ O ₅ 、Co ₂ O ₃ 、Rh ₂ O ₃ The composition comprises viologen, phthalocyanine, polythiophene and derivatives thereof, viologen, tetrathiafulvalene, metal phthalocyanine compounds, polydioxyethylenethiophene and polydioxyethylenethiophene-polystyrene sulfonic acid compound. In some embodiments, the electrochromic layer has a thickness of between about 1 μm to about 10 μm, e.g., 2, 3, 4, 5, 6, 7, 8, 9 μm. The switchable light transmissive layer 930 further comprises an electrochromic film 932, an electrolyte 934, and an ion storage conductor film 936. The pixel electrode 926 is provided with a pixel voltage (V) by the second metal layer 922 or the first metal layer 523 _pixel ) Pixel voltage and common voltage (V) of the common electrode 560 _com ) A pressure difference is generated therebetween so that the electrochromic film 932 generates an oxidation or reduction reaction, thereby controlling the penetration rate in the switching unit 102a and the switching unit 102b. In some embodiments, when electrically variedWhen the color film 932 undergoes an oxidation reaction, the electrochromic material in the electrochromic film 932 oxidizes to a transparent film, so that the

laser light

112, 114 can pass through the electrochromic layer, as shown by the switching unit 102a in fig. 9. In some embodiments, the switching unit 102a provides a penetration rate of about 60% to about 80%. When the electrochromic film 932 undergoes a reduction reaction, the electrochromic material in the electrochromic film 932 is reduced to a colored (e.g., blue) film, and thus the

lasers

112, 114 cannot pass through the electrochromic layer, as shown by the switching unit 102b in fig. 9. It should be noted that the color change of the electrochromic layer may vary depending on the nature of the material, and in other embodiments, the electrochromic layer may be converted to a colored film when oxidized and a transparent film when reduced. In some embodiments, the switching unit 102a provides a penetration rate of about 60% to about 80%, e.g., about 65, 70, 75%. In some embodiments, the switching unit 102b provides a penetration rate of less than about 20%, such as about 5, 10, 15%. In some embodiments, the switching unit 102c provides a penetration rate of about 20% to about 60%, e.g., about 30, 40, 50%. In performing mass transfer (as described in fig. 1), the switching unit 102c may protect the

micro LEDs

Referring to fig. 3, 5, 6, 7 and 9, the bulk transfer device further includes a carrier substrate 120B disposed under the selectively

switchable photomasks

100A, 100B, 100C and 100D and an adhesive layer 122B disposed under the carrier substrate 120B, wherein the carrier substrate 120B is in direct contact with the adhesive layer 122B. For a detailed description of transferring

micro LEDs

130R, 130G, 130B onto carrier substrate 140, refer to the description of fig. 1.

Fig. 10A, 10B and 10C are schematic perspective views of a mass transfer device according to some embodiments of the invention. Fig. 10A, 10B and 10C are based on fig. 3, with the addition of a removable mask 1000 disposed between the selectively switchable photomask 100 and the

carrier substrates

120R, 120G, 120B. In detail, in fig. 10A, the carrier substrate 120R and the adhesive layer 122R under the carrier substrate 120R are disposed under the movable mask 1000. In fig. 10B, the carrier substrate 120G and the adhesive layer 122G under the carrier substrate 120G are disposed under the movable mask 1000. In fig. 10C, the carrier substrate 120B and the adhesive layer 122B under the carrier substrate 120B are disposed under the movable mask 1000.

Referring to fig. 11, a schematic cross-sectional view of the macro-transfer apparatus of fig. 10A according to some embodiments of the present invention is shown. In detail, the movable mask 1000 is disposed under the selectively switchable photomask 100A. The movable mask 1000 has a plurality of holes 1010 separated from each other, the pixel electrode 540 has a projection P2 on the first substrate 510, each of the plurality of holes 1010 has a projection P5 on the first substrate 510, the projection P2 is larger than the projection P5, and the projection P5 is located in the projection P2. It should be noted that fig. 11 only shows a schematic cross-sectional view of the selectively switchable photomask 100A, however, other selectively

switchable photomasks

100B, 100C, 100D may be replaced with fig. 11, and the movable mask 1000 may be disposed below the selectively

switchable photomasks

100B, 100C, 100D, respectively.

As shown in fig. 10A, the carrier substrate 120R is disposed under the movable mask 1000, and the micro LED 130R is transferred onto the carrier substrate 140. Next, the movable mask 1000 is moved, as shown in fig. 10B, the carrier substrate 120G is disposed under the movable mask 1000, and the micro LEDs 130G are transferred onto the carrier substrate 140. Finally, the movable mask 1000 is moved again, as shown in fig. 10C, the carrier substrate 120B is disposed under the movable mask 1000, and the micro LEDs 130B are transferred onto the carrier substrate 140. The

micro LEDs

130R, 130G, 130B are transferred onto the carrier substrate 140 by controlling the position of the movable mask 1000, respectively. The mass transfer as in fig. 10A, 10B and 10C is completed, forming an array including

micro LEDs

130R, 130G, 130B.

In some embodiments, the selectively

switchable photomasks

100A, 100B, 100C, 100D of the present invention may be used on a mass transfer device to selectively transfer micro LEDs to be transferred onto a carrier substrate 140 by a laser 112, as shown in FIG. 1. It should be noted that the switching unit 102a through which the laser 112 can pass is shown without dots, the switching unit 102B through which the laser 112 cannot pass is shown with dense dots (like black), and the switching unit 102c through which the laser 112 can partially pass is shown with sparse dots (like gray), wherein the

micro LEDs

130R, 130G, 130B originally fixed on the

carrier substrate

120R, 120G, 120B will not fall off onto the carrier substrate 140 when the laser 112 cannot pass or can partially pass through the switching units.

In other embodiments, the selectively

switchable photomasks

100A, 100B, 100C, 100D of the present invention may be used in a laser bonding operation to selectively bond and secure micro LEDs to a thin film transistor substrate 150 by a laser 114, as shown in fig. 2. It should be noted that the switching unit 102a through which the laser 114 can pass is shown without dots, the switching unit 102B through which the laser 114 cannot pass is shown with dense dots (like black), and the switching unit 102c through which the laser 114 can partially pass is shown with sparse dots (like gray), wherein when the laser 114 cannot pass or can partially pass through the switching units, the melting point of the pads (e.g., tin pads) of the

micro LEDs

130R, 130G, 130B is not reached, and thus the bonding on the thin film transistor substrate 150 is not performed.

Fig. 12 is a schematic perspective view of a mass transfer device according to some embodiments of the invention. Specifically, the selectively switchable photomask 100E further includes an adhesive layer 122R, and the adhesive layer 122R is disposed under the selectively switchable photomask 100E and is in direct contact with the selectively switchable photomask 100E. In more detail, the selectively switchable photomask 100E is used as a carrier substrate 120R,micro LED 130R for the micro LEDs 130R, and the micro LEDs 130R are fixed to the selectively switchable photomask 100E by the adhesive layer 122R. In one embodiment, micro LEDs 130R on selectively switchable photomask 100E are transferred onto carrier substrate 140. In one embodiment, micro LEDs 130G on selectively switchable photomask 100E are transferred onto carrier substrate 140. In one embodiment, micro LEDs 130B on selectively switchable photomask 100E are transferred onto carrier substrate 140. For a detailed description of transferring

micro LEDs

The selectively switchable photomask 100E of the present invention can be used in a mass transfer device to selectively transfer micro LEDs to be transferred to a carrier substrate 140 by a laser 112, as shown in FIG. 1.

In summary, the present invention provides a selectively switchable photomask for use in bulk transfer operations and bonding operations. When the huge transfer operation is carried out, the selective switching photomask is arranged under the laser light source, so that a large number of micro LEDs can be transferred onto the carrier substrate, and the production efficiency is improved. When the bonding operation is performed, the selectively switchable photomask is arranged below the laser light source, so that a large number of micro LEDs can be bonded to the thin film transistor substrate, and the production efficiency is improved. Because the selective switching photomask of the invention can be simultaneously applied to mass transfer and bonding operations, the manufacturing cost can be greatly reduced, and the overall production efficiency can be further improved.

It will be apparent to those skilled in the art that various modifications and variations can be made in the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the appended claims.

Claims

1. A system for processing micro light emitting diodes includes a selectively switchable photomask for use with a laser light source,

wherein the selectively switchable photomask for use with a laser light source comprises:

a switching unit disposed under the laser light source, wherein the switching unit comprises:

a first substrate and a second substrate opposite to the first substrate;

a pixel electrode disposed on the first substrate;

a common electrode disposed on the second substrate;

the switchable light penetration layer is arranged between the pixel electrode and the common electrode;

a carrier substrate disposed under the selectively switchable photomask; and

the movable mask is arranged between the switching unit and the carrier substrate, the movable mask is provided with a plurality of holes which are separated from each other, the pixel electrode is provided with a first projection on the first substrate, each hole is provided with a second projection on the first substrate, the first projection is larger than the second projection, and the second projection is positioned in the first projection.

2. The system of claim 1, wherein the switchable light transmissive layer is a liquid crystal layer.

3. The system of claim 2, wherein the switching unit provides a penetration of less than 30%.

4. The system of claim 2, wherein the switching unit provides a penetration of 30% to 80%.

5. The system of claim 2, wherein the switching unit provides a penetration of 80% to 100%.

6. The system of claim 2, further comprising a light shielding element disposed between the second substrate and the common electrode, wherein the light shielding element has a third projection on the first substrate, the pixel electrode has a fourth projection on the first substrate, and the third projection and the fourth projection are staggered.

7. The system of claim 2, further comprising a light shielding element disposed on the second substrate, wherein the light shielding element has a third projection on the first substrate, the pixel electrode has a fourth projection on the first substrate, and the third projection and the fourth projection are staggered.

8. The system of claim 2, further comprising:

a thin film transistor element disposed on the first substrate and separated from the pixel electrode; and

the light shielding element is arranged on the thin film transistor element, wherein the light shielding element is provided with a third projection on the first substrate, the pixel electrode is provided with a fourth projection on the first substrate, and the third projection and the fourth projection are arranged in a staggered manner.

9. The system of claim 1, wherein the switchable light transmissive layer is an electrochromic layer.

10. The system of claim 9, wherein the switching unit provides a penetration of less than 20%.

11. The system of claim 9, wherein the switching unit provides a penetration of 20% to 60%.

12. The system of claim 9, wherein the switching unit provides 60% to 80% penetration.

13. The system of claim 1, further comprising an adhesive layer disposed under and in contact with the carrier substrate.