CN114068772A

CN114068772A - Selectively switchable photomask and system for processing micro light emitting diodes

Info

Publication number: CN114068772A
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: 2022-02-18
Anticipated expiration: 2041-11-03
Also published as: CN114068772B; TW202244992A; TWI759198B

Abstract

The invention discloses a selective switching photomask for a laser light source and a system for processing a micro light-emitting diode, wherein the selective switching photomask 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 pixel electrode, a common electrode and a switchable light transmission layer. The pixel electrode is arranged on the first substrate. The common electrode is disposed on the second substrate. The switchable light transmitting 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 the continuous progress of panel technology, micro light emitting diodes (micro LEDs) are applied to various displays, such as borderless displays, notebook computer displays, wearable displays, and the like. Although the micro LED has the advantages of high brightness, short reaction time, high luminous efficacy, etc., the assembly of the micro LED still faces the problems of low production efficiency, high manufacturing cost, etc.

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

Disclosure of Invention

The invention provides a selective switching type photomask for a 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 transmission layer. The pixel electrode is arranged on the first substrate. The common electrode is disposed on the second substrate. The switchable light transmitting 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 blocking element disposed between the second substrate and the pixel electrode, wherein the light blocking 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 alternately disposed.

In some embodiments, the selectively switchable photomask further comprises a light blocking element disposed on the second substrate, wherein the light blocking 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 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 a micro light emitting diode, which comprises a selective switching type photomask and a carrier substrate arranged below the selective switching type 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 holes separated from each other, wherein the pixel electrode has a first projection on the first substrate, each of the plurality of holes 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 selective switching type photomask and an adhesive layer, wherein the adhesive layer is arranged below the selective switching type photomask and is directly contacted with a first substrate of the selective switching type photomask.

The above description will be described in detail by embodiments, and further explanation will be provided for the technical solution of the present invention.

Drawings

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

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

FIG. 2 is a 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 bulk transfer device 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 a selectively switchable photomask 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 cross-sectional view of a selectively switchable photomask according to some embodiments of the present invention;

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

FIG. 11 is a schematic cross-sectional view of the bulk transfer device of FIG. 10A in accordance with some embodiments of the present invention;

fig. 12 is a schematic perspective view of a bulk transfer device according to some embodiments of the invention.

Description of the symbols

100 selectively switchable photomask

100A selective switching photomask

100B Selective switching photomask

100C selective switching photomask

100D Selective switching photomask

100E Selective switching photomask

102 switching unit

102a switching unit

102b switching unit

102c switching unit

110 laser light source

112 laser

114 laser

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 gate electrode

523 first Metal layer

524 gate insulating layer

526 channel layer

528 source/drain

529 second metal layer

530 passivation film

540 Pixel electrode

550 second substrate

560 common electrode

570 light-shielding member

580 switchable light transmissive layer

582a liquid crystal molecules

582b liquid crystal molecules

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 is a region

P1 projection

P2 projection

P3 projection

P4 projection

P5 projection

X is the direction

Z is the direction

Detailed Description

In order to make the description of the present invention more complete and complete, reference is made to the accompanying drawings, in which like numerals designate the same or similar elements, and the various embodiments described below.

In the following description, for purposes of explanation, numerous implementation details are set forth in order to provide a thorough understanding of the various embodiments of the present invention. It should be understood, however, that these implementation details are not to be interpreted as limiting the invention. That is, in some embodiments of the invention, such implementation details are not necessary. In addition, some conventional structures and elements are shown in simplified schematic form in the drawings.

In this context, a range of values from one value to another is a general expression avoiding any recitation of all values in the range in the specification. Thus, recitation of a range of values herein is intended to encompass any value within the range and any smaller range defined by any value within the range, as if the range and smaller range were explicitly recited in the specification.

In the embodiments and claims, the terms "a" and "an" can refer broadly to the singular or the plural unless the context specifically states otherwise. As used herein, the terms "about," "approximately," or "approximately" generally refer to a numerical value having an error or range of about twenty percent, preferably about ten percent, and more preferably about five percent.

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

The present invention provides a selectively switchable photomask that can be used for bulk transfer operations and bonding operations. When carrying out the huge transfer operation, set up selective switch formula photomask under laser light source, can transfer a large amount of micro LED to on the carrier base plate to promote production efficiency. When the bonding operation is performed, the selective switching type photomask is arranged under the laser light source, a large number of micro LEDs can be bonded to the thin film transistor substrate, and thus, the production efficiency is improved. The selective switching photomask can be simultaneously applied to mass transfer and bonding operation, so that the manufacturing cost can be greatly reduced, and the overall production efficiency is further improved. Various embodiments of the selectively switchable photomask of the present invention will be described in detail below.

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

micro LEDs

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

micro LEDs

130R and 130G are transferred before the micro LED130B is transferred. In 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-mentioned transfer operation to form the carrier substrate 140 carrying the

micro LEDs

130R, 130G, 130B, respectively. In the present embodiment, the micro LED 130R 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 a carrier substrate and an adhesive layer carrying a blue micro LED.

In some embodiments, the laser light source 110 may be a titanium sapphire laser, which may have a wide wavelength tuning range (e.g., wavelengths between about 670nm and about 1200 nm). In other embodiments, the laser source 110 may be rare earth doped glass (SiO)₂) The optical fiber is used as the optical fiber laser of the gain medium. In some embodiments, the laser 112 can be Nd: YAG, Nd: YVO₄Or Yb: YAG, which can provide peak wavelengths (peak wavelength) of about 266nm, 355nm, 532nm, but is not limited thereto. In other embodiments, laser 112 may be a gaseous laser, for example, providing KrF at about 248nm, XeF at about 353nm, ArF at about 193nm, XeCl at about 308nm, F at about 157nm₂The excimer laser of (1); for example, a helium neon laser at about 632.8nm, a carbon dioxide laser at about 1064nm, a carbon monoxide laser at about 6000nm to about 8000nm, a nitrogen laser at about 337.1nm, a helium cadmium laser at about 442nm, a metal vapor laser, a metal halide laser, or a mixed gas laser may be provided, but not limited thereto.

It should be noted that the switching

units

102a, 102b of the selectively switchable photomask 100 can be adjusted to change the light transmittance thereof. In other words, the laser 112 shown in fig. 1 can pass through the switching unit 102a but cannot pass through the switching unit 102 b. Thus, bulk transfer may also be referred to as selective laser transfer. Furthermore, in some embodiments, the macro transfer may selectively transfer the micro LEDs 130R onto the carrier substrate 140, selectively transfer the micro LEDs 130G onto the carrier substrate 140, and selectively transfer the micro LEDs 130B onto the carrier substrate 140. The plurality of

micro LEDs

130R, 130G, 130B are combined and arranged to form a micro LED array by a bulk transfer device as shown in fig. 1.

Fig. 2 is a 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 bonding operation shown in fig. 2 is performed. The selectively switchable photomask 100 is placed under the laser source 110 providing the laser 114, and the carrier substrate 140 in fig. 1 is turned over (e.g., by 180 degrees) so that the

micro LEDs

130R, 130G, 130B face the tft substrate 150. Similarly, when 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, and 130B, so that the pads (e.g., tin pads) on the

micro LEDs

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

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

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, 102 c. It should be noted that, in the present drawing, the switching unit 102a through which the

laser beams

112 and 114 can pass is illustrated as a rectangular parallelepiped without dots, the switching unit 102b through which the

laser beams

112 and 114 cannot pass is illustrated as a rectangular parallelepiped with dense dots (like black), and the switching unit 102c through which the

laser beams

112 and 114 can partially pass is illustrated as a rectangular parallelepiped with sparse dots (like gray). Various embodiments of the selectively switchable photomask 100 will be described in detail below with reference to the accompanying drawings.

Fig. 5-7 are 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 selective switching type photomask of the region R of fig. 4. The region R includes the left switching means 102a and the right switching means 102 b. It should be understood that some elements in fig. 4 are not shown in fig. 5-7 (e.g., wiring) for simplicity of the drawing.

Fig. 5 is a cross-sectional view of a selectively switchable photomask 100A according to some embodiments of the present invention. The selectively switchable photomask 100A includes a left switching cell 102a and a right switching cell 102 b. The selectively switchable photomask 100A includes a first substrate 510, a thin film transistor device 520, a passivation film 530, a pixel electrode 540, a second substrate 550, a common electrode 560, a light blocking device 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 the thin film transistor device 520, the passivation film 530, the pixel electrode 540, the common electrode 560, the light blocking element 570, the switchable light transmissive layer 580, and the spacer 590 are disposed between the first substrate 510 and the second substrate 550.

As shown in fig. 5, the thin film transistor device 520 is disposed on the first substrate 510, and the thin film transistor device 520 includes a gate 522, a 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 device 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 crosses the

switching cells

102a and 102 b. The passivation film 530 extends over the gate insulating layer 524 and continuously crosses the

switching cells

102a and 102 b. 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 electrodes 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, 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, gate 522 and/or source/drain 528 have a thickness (in direction X) 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 N-type dopants and has 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, such as 0.15, 0.2, 0.25 μm. 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, such as 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 the second substrate 550 and continuously crosses the

switching cells

102a and 102 b. In some embodiments, the pixel electrode 540 and/or the common electrode 560 may be made of Indium Tin Oxide (ITO) or Indium Zinc Oxide (IZO) and have a thickness of about 0.04 μm to about 0.2 μm, such as 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 located 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, the pixel electrode 540 has a projection P2 on the first substrate 510, and the projections P1 and P2 are disposed alternately. In detail, the light shielding element 570 is disposed above the thin film transistor element 520 in the direction Z, and thus, when the selective switching photomask 100A is irradiated with the

laser beams

112 and 114 from above, the light shielding element 570 can protect the thin film transistor element 520 from being damaged. It should be noted that the light shielding element 570 in fig. 5 is illustrated to cover the width of the source/drain 528, however, the light shielding element 570 with a larger width is also included in the embodiments of the present invention, for example, the width of the entire tft element 520 is included. The light blocking element 570, which may also be referred to as a Black Matrix (BM), may have a patterned matrix to form an array similar to that shown in FIG. 4. In some embodiments, the shading element 570 may be composed of a black resin, including a resin, carbon, a photoinitiator, a solvent, an additive (e.g., an additive accelerator, a curing accelerator, and/or a surfactant), or other similar material, and has a thickness of between about 1 μm and about 3 μm, such as 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, 582 b. In some embodiments, the switchable light transmissive layer 580 has a thickness between about 2 μm to about 4 μm, such as 2.5, 3, 3.5 μm. The switching of the TFT element 520 and the

liquid crystal molecules

582a, 582b in the liquid crystal layer may be controlled by an external controller (not shown). Controls the switching of the TFT element 520, and charges the pixel electrode 540 to a pixel voltage (V)_pixel) So that the pixel voltage is equal to the common voltage (V) of the common electrode 560_com) A pressure difference is generated therebetween. The voltage applied to each pixel electrode 540 can be controlled by the corresponding tft element 520, such 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 difference, thereby controlling the transmittance in the switching unit 102a and the switching unit 102 b. When the liquid crystal molecules 582a are aligned, the laser light112. 114 may pass through the liquid crystal layer as shown by the switching unit 102a in fig. 5.

In some embodiments, the switching unit 102a provides a penetration rate of about 80% to about 100%, for example 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 less than about 30% penetration, for example about 5, 10, 15, 20, 25% penetration. In some embodiments, the switching unit 102c provides a penetration of about 30% to about 80%, for example about 40, 50, 60, 70%. When a huge amount of transfer is performed (as described in fig. 1), the switching unit 102c can protect the

micro LEDs

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

micro LEDs

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

As shown in fig. 5, the 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 the first substrate 510 and the second substrate 550 are packaged.

Referring to both FIG. 1 and FIG. 5, in some embodiments, when the selectively switchable photomask 100A of FIG. 5 is used as a bulk 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 light source 110 provides a power range of about 0.1mW to about 10mW, such as 0.5, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 9 mW. In some embodiments, the laser 112 may have a duration of about 1ms to about 1fs, such as 1 μ s, 1ns, 1 ps.

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

Fig. 6 is a cross-sectional view of a selectively switchable photomask 100B according to some embodiments of the present invention. The selective switching photomask 100B of FIG. 6 is similar to the selective switching photomask 100A of FIG. 5, with the difference being the position of the light blocking element 570. The light-shielding element 570 of the selective switchable photomask 100B is disposed on the second substrate 550 and is far away from the first substrate 510, wherein the light-shielding element 570 has a projection P3 on the first substrate 510, the pixel electrode 540 has a projection P2 on the first substrate 510, and the projections P3 and P2 are disposed alternately. It should be noted that the same or similar elements in fig. 6 as those in fig. 5 are given the same symbols, and the description thereof is omitted, and will not be repeated.

Fig. 7 is a cross-sectional view of a selectively switchable photomask 100C according to some embodiments of the present invention. The selective switching photomask 100C of FIG. 7 is similar to the selective switching photomask 100A of FIG. 5, with the difference being the position of the light blocking element 570. The light-shielding element 570 of the selective switchable mask 100C is disposed on the tft element 520, wherein the light-shielding element 570 has a projection P4 on the first substrate 510, the pixel electrode 540 has a projection P2 on the first substrate 510, and the projections P4 and P2 are disposed alternately. It should be noted that the same or similar elements in fig. 7 as those in fig. 5 are given the same reference numerals, and the description thereof is omitted, and will not be repeated.

Fig. 8 is a circuit diagram of a selectively switchable photomask 100D according to some embodiments of the present invention. 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

laser beams

112 and 114 can partially pass is illustrated as a rectangular parallelepiped with sparse dots (like gray). A variation of the selective switched photomask 100 will be described in detail with reference to the accompanying drawings.

Fig. 9 is a cross-sectional view of a selectively switchable photomask 100D according to some embodiments of the present invention. The selectively switchable photomask 100D includes a left switching cell 102a and a right switching cell 102 b. 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 the control element 920, the switchable light transmissive layer 930, and the 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 522 and the first metal layer 523 are disposed on the first substrate 510, the gate insulating layer 524 is disposed on the gate 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, a gate insulating layer 524 extends over the first substrate 510 and continuously crosses the

switching cells

102a and 102b, and a passivation film 924 extends over the gate insulating layer 524 and crosses the

switching cells

102a and 102 b. It should be noted that the same or similar elements in fig. 9 as those in fig. 5 are given the same reference numerals, and the description thereof is omitted, and will not be repeated. In some embodiments, the second metal layer 922 has the same or similar features as the gate 522. In some embodiments, the passivation film 924 has the same or similar features as the passivation film 530. Pixel electrode 926 has the same or similar features as pixel electrode 540.

With 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 WO₃、MoO₃、Nb₂O₅、TiO₂、NiO、IrO₂、C₁₈Fe₇N₁₈、V₂O₅、Co₂O₃、Rh₂O₃Viologen, phthalocyanine, polythiophene and derivatives thereof, viologen, tetrathiafulvalene, metal phthalocyanine compounds, polydioxyethylenethiophene and polydioxyethylthiophene-polystyrene sulfonic acid complex. In some embodiments, the electrochromic layer has a thickness between about 1 μm to about 10 μm, such as 2, 3, 4, 5, 6, 7, 8, 9 μm. The switchable light transmissive layer 930 also includes an electrochromic film 932, an electrolyte 934, and an ion storage conductor film 936. The pixel electrode 926 is supplied with a pixel voltage (V) using 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 transmittance in the

switching cells

102a and 102 b. In some embodiments, when the electrochromic film 932 undergoes an oxidation reaction, the electrochromic material in the electrochromic film 932 may oxidize to a transparent film, and thus the

laser light

112, 114 may pass through the electrochromic layer, as shown by the switching cell 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 generates a reduction reaction, the electrochromic material in the electrochromic film 932 is reduced to a film having a color (e.g., blue), and thus the

laser light

112, 114 cannot pass through the electrochromic layer, as shown by the switching unit 102b in fig. 9. Note that the electrochromic layer may have different color changing modes according to material properties, and in other embodiments, the electrochromic layer may be converted into a colored film when an oxidation reaction occurs, and may be converted into a transparent film when a reduction reaction occurs. In some embodiments, the switching unit 102a provides a penetration of about 60% to about 80%, for example about 65, 70, 75%. In some embodiments, the switching unit 102b provides less than about 20% penetration, for example about 5, 10, 15% penetration. In some embodiments, the switching unit 102c provides a penetration rate of about 20% to about 60%, for example about30. 40, 50% penetration rate. When a huge amount of transfer is performed (as described in fig. 1), the switching unit 102c can 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 selective-switching

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 the

micro LEDs

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

Fig. 10A, 10B and 10C are schematic perspective views illustrating a bulk transfer device according to some embodiments of the invention. Fig. 10A, 10B and 10C illustrate the addition of a removable mask 1000 disposed between the selectively switchable photomask 100 and the

carrier substrates

120R, 120G, 120B, in accordance with fig. 3. In detail, in fig. 10A, a carrier substrate 120R and an adhesive layer 122R under the carrier substrate 120R are disposed under a movable mask 1000. In fig. 10B, a carrier substrate 120G and an adhesive layer 122G under the carrier substrate 120G are disposed under the movable mask 1000. In fig. 10C, a carrier substrate 120B and an adhesive layer 122B under the carrier substrate 120B are disposed under the movable mask 1000.

Referring to fig. 11, a cross-sectional view of the bulk transfer device of fig. 10A is shown, according to some embodiments of the present invention. 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 selective switching photomask 100A, however, other

selective switching photomasks

100B, 100C, 100D may be replaced in fig. 11, and the movable mask 1000 may be disposed under the

selective switching photomasks

100B, 100C, 100D, respectively.

As shown in fig. 10A, the carrier substrate 120R is disposed under the movable mask 1000, and the micro LEDs 130R are 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 macro transfer as shown in fig. 10A, 10B and 10C is completed to form an array including the

micro LEDs

130R, 130G, 130B.

In some embodiments, the selectively

switchable photomasks

100A, 100B, 100C, 100D of the present invention can be used on 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. It should be noted that the switching unit 102a through which the laser 112 can pass is illustrated as having no dots, the switching unit 102B through which the laser 112 can not pass is illustrated as having dense dots (like black), and the switching unit 102c through which the laser 112 can partially pass is illustrated as having sparse dots (like gray), wherein when the laser 112 can not pass or can partially pass through the switching unit, the

micro LEDs

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

carrier substrates

120R, 120G, 120B will not fall off onto the carrier substrate 140.

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 fix micro LEDs on the TFT substrate 150 via the laser 114, as shown in FIG. 2. It should be noted that the switching unit 102a through which the laser 114 can pass is illustrated as having no dots, the switching unit 102B through which the laser 114 can not pass is illustrated as having dense dots (like black), and the switching unit 102c through which the laser 114 can partially pass is illustrated as having sparse dots (like gray), wherein when the laser 114 can not pass or can partially pass through the switching unit, the melting point of the pads (e.g., tin pads) of the

micro LEDs

130R, 130G, 130B is not reached, and therefore the bonding on the tft substrate 150 is not achieved.

Fig. 12 is a schematic perspective view of a bulk transfer device according to some embodiments of the invention. In detail, the selective switching mask 100E further includes an adhesive layer 122R, and the adhesive layer 122R is disposed under the selective switching mask 100E and directly contacts the selective switching mask 100E. In more detail, the selectively switchable photomask 100E is used as the carrier substrate 120R of the micro LED 130R, and the micro LED 130R fixes the micro LED 130R on the selectively switchable photomask 100E through the adhesive layer 122R. In one embodiment, the micro LEDs 130R on the selectively switchable photomask 100E are transferred onto the carrier substrate 140. In one embodiment, the micro LEDs 130G on the selectively switchable photomask 100E are transferred onto the carrier substrate 140. In one embodiment, the micro LEDs 130B on the selectively switchable photomask 100E are transferred onto the carrier substrate 140. For a detailed description of transferring the

micro LEDs

The selectively switchable photomask 100E of the present invention may be used on 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 that can be used for bulk transfer operations and bonding operations. When carrying out the huge transfer operation, set up selective switch formula photomask under laser light source, can transfer a large amount of micro LED to on the carrier base plate to promote production efficiency. When the bonding operation is performed, the selective switching type photomask is arranged under the laser light source, a large number of micro LEDs can be bonded to the thin film transistor substrate, and thus, the production efficiency is improved. The selective switching photomask can be simultaneously applied to mass transfer and bonding operation, so that the manufacturing cost can be greatly reduced, and the overall production efficiency is 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 selectively switchable photomask for use with a laser light source, comprising:

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

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; and

a switchable light transmissive layer disposed between the pixel electrode and the common electrode.

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

3. The selectively switchable photomask of claim 2, wherein the switching unit provides a transmittance of less than about 30%.

4. The selectively switchable photomask of claim 2, wherein the switching unit provides a transmittance of about 30% to about 80%.

5. The selectively switchable photomask of claim 2, wherein the switching unit provides a transmittance of about 80% to about 100%.

6. The selectively switchable photomask of claim 2, further comprising a light blocking element disposed between the second substrate and the common electrode, wherein the light blocking 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.

7. The selectively switchable photomask of claim 2, further comprising a mask element disposed on the second substrate, wherein the mask 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.

8. The selectively switchable photomask of claim 2, further comprising:

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

and 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 manner.

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

10. The selectively switchable photomask of claim 9, wherein the switching unit provides a transmittance of less than about 20%.

11. The selectively switchable photomask of claim 9, wherein the switching unit provides a transmittance of about 20% to about 60%.

12. The selectively switchable photomask of claim 9, wherein the switching unit provides a transmittance of about 60% to about 80%.

13. A system for processing micro-leds, comprising:

the selectively switchable photomask of any of claims 1-12; and

a carrier substrate disposed below the selectively switchable photomask.

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

15. The system of claim 13, further comprising a moveable mask disposed between the switching unit and the carrier substrate, the moveable mask having a plurality of apertures separated from one another, wherein the pixel electrode has a first projection on the first substrate, each of the apertures has a second projection on the first substrate, the first projection is larger than the second projection, and the second projection is in the first projection.

16. A system for processing micro-leds, comprising:

the selectively switchable photomask of any of claims 1-12; and

and the adhesive layer is arranged below the selective switching photomask and is directly contacted with the first substrate of the selective switching photomask.