TW202040833A - Method for transferring micro device - Google Patents

Abstract

A method for transferring a micro device is provided. The method includes: preparing a carrier substrate with the micro device thereon, wherein an adhesive layer is between and in contact with the carrier substrate and the micro device; picking up the micro-device from the carrier substrate by a transfer head; forming a liquid layer on a receiving substrate; and placing the micro device over the receiving substrate by the transfer head such that the micro device is in contact with the liquid layer and is gripped by a capillary force; and moving the transfer head away from the receiving substrate such that the micro device is detached from the transfer head and is stuck to the receiving substrate.

Description

Method for transferring micro components

The present disclosure relates to a method for transferring micro components from a carrier substrate to a receiving substrate.

The statements here only provide background information related to the present disclosure, and do not necessarily constitute prior art.

Traditional techniques for transferring components include transferring from a transfer wafer to a receiving substrate by wafer bonding. One such implementation is "direct bonding", which involves a bonding step of the element array from the transfer wafer to the receiving substrate, followed by removal of the transfer wafer. Another such embodiment is "indirect bonding", which involves two bonding/peeling steps. In indirect bonding, the transfer head can pick up the element array from the supply substrate, then bond the element array to the receiving substrate, and then remove the transfer head.

Some embodiments of the present disclosure propose a method for transferring micro-components. The method includes: preparing a carrier substrate with micro components on the carrier substrate, wherein the adhesive layer is located between the carrier substrate and the micro components and contacts the carrier substrate and the micro components; picking up the micro components from the carrier substrate by a transfer head; A liquid layer is formed on the substrate; the micro component is placed on the receiving substrate by the transfer head, so that the micro component is in contact with the liquid layer and is clamped by capillary force; and the transfer head is moved away from the receiving substrate, so that the micro component is separated from the transfer head and Adhesively fixed to the receiving substrate.

In order to make the above-mentioned features and advantages of the present disclosure more obvious and understandable, the following specific embodiments are described in detail in conjunction with the accompanying drawings.

100‧‧‧Method

110‧‧‧Operation

120‧‧‧Operation

130‧‧‧Operation

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210‧‧‧Carrier substrate

220‧‧‧Micro components

230‧‧‧Adhesive layer

240‧‧‧Transfer head

242‧‧‧Clamping area

244‧‧‧Cave

250‧‧‧Liquid layer

252‧‧‧ Meniscus

260‧‧‧Receiving board

262‧‧‧Conductive pad

When read in conjunction with the accompanying drawings, the following detailed description will best understand the aspect of this disclosure. It should be noted that according to standard practice in the industry, each feature may not be drawn to scale. In fact, the dimensions of the described features can be increased or decreased for the purpose of clarity of the discussion.

FIG. 1 is a flowchart of a method for transferring micro-components from a carrier substrate to a receiving substrate in some specific embodiments of the present disclosure;

2 is a schematic cross-sectional view of an intermediate step of the method for transferring micro-components in some specific embodiments of the present disclosure;

3 is a schematic cross-sectional view of an intermediate step of the method for transferring micro-components in some specific embodiments of the present disclosure;

4A is a schematic cross-sectional view of an intermediate step of the method for transferring micro-components in some specific embodiments of the present disclosure;

4B is a schematic cross-sectional view of an intermediate step of the method for transferring micro-components in some specific embodiments of the present disclosure;

5A is a schematic cross-sectional view of an intermediate step of a method for transferring micro-components in some specific embodiments of the present disclosure;

Fig. 5B is used to transfer the miniature in some specific embodiments of the disclosure A schematic cross-sectional view of an intermediate step of the method of the component;

6 is a schematic cross-sectional view of an intermediate step of the method for transferring micro-components in some specific embodiments of the present disclosure;

FIG. 7A is a schematic cross-sectional view of an intermediate step of the method for transferring micro-components in some specific embodiments of the present disclosure; and

FIG. 7B is a schematic cross-sectional view of an intermediate step of the method for transferring micro-components in some specific embodiments of the present disclosure.

In order to further explain the technical means and effects of the present disclosure to achieve the intended purpose of the invention, in conjunction with the accompanying drawings and preferred embodiments, the method for transferring micro-components according to the present disclosure, its specific implementation, structure, The methods, steps, characteristics and effects are described in detail below.

The aforementioned and other technical content, features and effects of the present disclosure will be clearly presented in the following detailed description of the preferred embodiment with reference to the accompanying drawings. Through the description of the specific implementation manners, it is possible to have a more in-depth and specific understanding of the technical means and effects adopted by the present disclosure to achieve the predetermined purpose. However, the attached drawings are only for reference and explanation, and are not used to limit the present disclosure. .

In order to simplify the drawings, some conventionally known and conventional structures and elements are shown in the drawings in a simple schematic manner. In addition, unless otherwise indicated, the same component symbols in different drawings may be regarded as corresponding components. The drawing in these drawings is to clearly express the connection relationship between the elements in these embodiments, and does not illustrate the actual size of each element.

Fig. 1 is a flowchart of a method for transferring a micro-component from a carrier substrate to a receiving substrate. 2 to 7B are intermediate steps of the method 100 of FIG. 1 Schematic cross-sectional view. Refer to Figures 1 to 7B. The method 100 starts at operation 110, where a carrier substrate 210 is prepared, and the carrier substrate 210 has micro-components 220 thereon. The adhesive layer 230 is located between the carrier substrate 210 and the micro device 220 and is in contact with the carrier substrate 210 and the micro device 220 (as shown in FIG. 2). The method 100 continues to operation 120, where the micro-component 220 is picked up from the carrier substrate 210 by the transfer head 240 (as shown in FIG. 3). The method 100 continues with operations 130 and 140, in which the liquid layer 250 or the patterned liquid layer 250 is formed on the receiving substrate 260 (as shown in FIGS. 4A and 4B), and then the picked-up micro-component 220 is placed on the receiving substrate 260 by the transfer head 240 On the receiving substrate 260, the micro-elements 220 are in contact with the liquid layer 250 and clamped by the capillary force generated by the liquid layer 250 (as shown in FIGS. 5A, 5B, and 6). The method 100 continues with operation 150, in which the transfer head 240 is moved away from the receiving substrate 260, so that the micro-component 220 is separated from the transfer head 240 and adhered to the receiving substrate 260 (as shown in FIGS. 7A and 7B).

Although only the "one" micro-elements 220 are mentioned in the previous paragraph and FIG. 1, in practical applications, "multiple" micro-elements 220 can be used and still fall within the scope of this disclosure, as will be described in the following specific embodiments Illustrative.

Refer to Figure 2. As described above, the adhesive layer 230 is located between the carrier substrate 210 and the plurality of micro devices 220. In particular, the adhesive layer 230 is in contact with the carrier substrate 210 and the micro device 220. In some embodiments, the formation of the adhesive layer 230 is performed by coating a material with adhesive ability on the carrier substrate 210. The adhesive layer 230 may be coated by a spin coater, a slit coater, or any combination thereof. In some embodiments, the adhesion layer 230 may be made of an organic material with adhesion capabilities, such as epoxy, polymethylmethacrylate (PMMA), polysiloxane (polysiloxanes), silicone (silicone) or any combination thereof. In addition, the adhesion layer 230 may have a thickness of about 1 micrometer to about 100 micrometers.

The adhesive force F1 is the adhesive force of the adhesive layer 230 to each micro-component 220, and has a value of F11. In some specific embodiments, the adhesive force F1 is the adhesive force of the adhesive layer 230 to each micro element 220 after being reduced, and has a value of F12. In some embodiments, the value F11 (the value of the adhesion force F1 without the reduction) is greater than the value F12. The reduction is to reduce the original adhesive force of the adhesive layer 230 to each micro component 220, which can be performed before picking up some micro components 220. In some specific embodiments, the reduction may be performed by heating, cooling, applying an electric field, electromagnetic radiation, ultrasonic waves, mechanical force, pressure, or any combination thereof on the adhesive layer 230, but it should not be limited thereto. In some embodiments, the lateral length L of one of the micro-elements 220 is less than or equal to about 50 microns. The lateral length is measured in direction Y. The direction Y is perpendicular to the thickness direction Z, and the thickness direction Z is perpendicular to the plane extending direction of the carrier substrate 210. For example, for a micro-element 220 having a surface area of about 10 microns×10 microns, the reduced adhesion force F1 has a value F12 of about 50 nano-Newtons (nN). The specific embodiments of the present disclosure are not limited to this. Appropriate modifications to the adhesive layer 230 can be performed according to actual applications. The adhesion force F1 may include Waals forces, but should not be limited thereto.

In some embodiments, the carrier substrate 210 may be a rigid substrate. The rigid substrate may be made of glass, silicon (silicon), polycarbonate (PC), acrylonitrile butadiene styrene (ABS), or any combination thereof. The specific embodiments of the present disclosure are not limited to this. Appropriate modifications to the carrier substrate 210 depending on actual applications can be performed.

In some embodiments, the micro-component 220 may be a light emitting structure, such as a compound semiconductor having an energy gap corresponding to a specific region in the spectrum. For example, the light emitting structure may include one or more layers based on II-VI materials (such as ZnSe, ZnO) or III-V nitride materials (such as GaN, AlN, InN, InGaN, GaP, AlInGaP, AlGaAs or alloys thereof). In some other embodiments, the micro-component 220 may also be an integrated circuit (IC) or a micro-electromechanical system (MEMS) component, and should not be limited thereto.

Refer to Figure 3. As described above, some micro-elements 220 are picked up from the carrier substrate 210 by the transfer head 240. In some embodiments, the transfer head 240 may apply picking pressure or picking force on each micro-component 220 by, for example, vacuum, adhesion, magnetic attraction, electrostatic attraction, etc. In the following, only adhesive force will be discussed, but the other types of force described above are still within the scope of the present disclosure. In some specific embodiments, the transfer head 240 may have a plurality of clamping areas 242 for picking and placing the micro components 220. There may also be a cavity 244 in the clamping area 242, and the cavity 244 is configured to accommodate a position of an object not to be picked up and/or placed. In addition, when the micro-component 220 is placed on the receiving substrate 260, objects originally on the receiving substrate 260 will not be disturbed. There may also be a cavity 244 in the clamping area 242. The clamping area 242 of the transfer head 240 may be made of a material with adhesive ability, or the transfer head 240 may have a patterned adhesive layer thereon, so that when the transfer head 240 contacts the micro-component 220, the adhesive force F2 Pick up each micro component 220. In some embodiments, for a micro-component 220 having a surface area of about 10 μm×10 μm, the adhesion force F2 for one micro-component 220 is about 100 nN to 1000 nN. The adhesion force F2 may include Van der Waals force, but should not be limited to this.

As mentioned above, in some specific embodiments, you can The original adhesion force F1 having the value F11 is previously reduced to form the adhesion force F1 having the value F12, so that the difference between the adhesion force F2 and the adhesion force F1 is increased, so as to promote the performance of picking up the micro-component 220.

Refer to Figures 4A and 4B. As described above, the liquid layer 250 is formed on the receiving substrate 260. The liquid layer 250 may be formed as a layer on the receiving substrate 260, as shown in FIG. 4A, or patterned to receive discrete parts on the substrate 260, as shown in FIG. 4B. In FIG. 4B, the patterned liquid layer 250 may be the location on which the micro-component 220 is placed. The receiving substrate 260 may be a display substrate, a light emitting substrate, a substrate having functional elements such as a transistor or an integrated circuit, or a substrate having metal redistribution lines, but is not limited thereto. In some embodiments, the liquid layer 250 may be formed by lowering the temperature of the receiving substrate 260 in an environment that includes vapor, so that at least a portion of the vapor is condensed to form the liquid layer 250 on the receiving substrate 260. In particular, the liquid layer 250 or the patterned liquid layer 250 may be formed on the conductive pad 262 of the receiving substrate 260, but should not be limited thereto. In some embodiments, the area of each conductive pad 262 is less than or equal to about 1 square millimeter. In some specific embodiments, the temperature of the receiving substrate 260 is reduced to approximately the dew point, so that water vapor in the environment condenses to form liquid water used as the liquid layer 250. In addition, the formation of the liquid layer 250 can also be achieved by spraying steam, inkjet printing, roll coating, dip coating, or the like.

Refer to Figures 5A, 5B and 6. As described above, the micro components 220 that have been picked up are placed on the receiving substrate 260 by the transfer head 240 so that each micro component 220 is in contact with the liquid layer 250 and is clamped by the capillary force F31. Specifically, the micro element 220 is placed close to the conductive pad 262 so that the liquid layer 250 can clamp the micro element 220. The meniscus 252 of the liquid layer 250 as shown in FIG. 6 is caused by the capillary force F31. The micro component 220 is covered by the liquid layer between the micro component 220 and the conductive pad 262 The capillary force F31 generated by 250 clamps. In some specific embodiments, when the micro component 220 is clamped by the capillary force F31, the thickness of the liquid layer 250 is less than the thickness of the micro component 220. Note that the order of operation 130 and operation 140 may be exchanged. That is, the micro-component 220 may be placed on and in contact with the conductive pad 262, and then the liquid layer 250 is formed on the receiving substrate 260.

Refer to Figures 7A and 7B. As described above, after the micro component 220 is clamped by the capillary force F31, the micro component 220 is separated from the transfer head 240. In some embodiments, the micro-component 220 is adhered to the adhesive layer 230 by the adhesive force F1, and the adhesive force F1 has the value F11 or the value F12 as described above. Some micro-components 220 are adhered to the transfer head 240 by the adhesion force F2, and the capillary force F31 is greater than the adhesion force F2, so that after the placement, when the transfer head 240 is moved away from the receiving substrate 260, the micro-elements 220 are separated from the transfer head 240 and It is adhered and fixed to the receiving substrate 260, as shown in FIG. 7A.

In some specific embodiments, the method 100 further includes evaporating the liquid layer 250 so that at least one of the micro-elements 220 is attached to one of the conductive pads 262 and is in electrical contact with the conductive pad 262. The evaporation of the liquid layer 250 can be achieved by, for example, increasing the temperature of the receiving substrate 260 or the conductive pad 262. The micro-elements 220 may respectively have electrodes on them for electrically contacting the conductive pads 262. In some embodiments, the transfer head 240 is moved away from the receiving substrate 260 before the liquid layer 250 is evaporated. In this case, the force F3 for overcoming the adhesive force F2 is the capillary force F31 as described above, and the capillary force F31 is greater than the adhesive force F2. In some embodiments, after the liquid layer 250 is evaporated, the transfer head 240 is moved away from the receiving substrate 260. In this case, the force F3 for overcoming the adhesion force F2 is the adhesion fixing force F32 generated between a micro-component 220 and a conductive pad 262 after the evaporation, and the adhesion fixing force F32 is greater than the adhesion force F2.

In some embodiments, the method 100 further includes reducing the temperature of the receiving substrate 260 or the conductive pad 262 before the transfer head 240 is moved away from the receiving substrate 260, so that the liquid layer 250 is frozen. When the liquid layer 250 is frozen, another gripping force F33 generated by the frozen liquid layer 250 is applied to the micro element 220. Generally speaking, the gripping force F33 is greater than the adhesion force F2.

In some embodiments, before the transfer head 240 is moved away from the receiving substrate 260, the combination of the transfer head 240, the micro-component 220, the liquid layer 250, and the receiving substrate 260 is heated through the adhesion between the micro-component 220 and the receiving substrate 260 F34 forms a bond between the micro-component 220 and the receiving substrate 260. The adhesion force F34 is greater than the adhesion force F2.

In short, the force F3 includes one of the following forces: (1) the capillary force F31 generated by the liquid layer 250 between the micro component 220 and the conductive pad 262; (2) the adhesion between the micro component 220 and the conductive pad 262 Fixing force F32, where the difference between (1) and (2) depends on whether the liquid layer 250 is evaporated; (3) the holding force F33 generated by the frozen liquid layer 250; and (4) the micro-elements 220 and The adhesion force F34 between the substrates 260 is received.

In some specific embodiments, the lateral length of the micro-elements 220 may be less than or equal to 50 microns. The limitation on the lateral length is to ensure the feasibility of the above specific embodiment, because some forces (such as the capillary force F31 caused by the liquid layer 250, after evaporating the liquid layer 250 between the micro-component 220 and the conductive pad 262 The adhesion and fixing force F32 caused by the interface and the gripping force F33 caused by the frozen liquid layer 250 can be greatly changed according to the lateral length of the micro-component 220. It should be noted that when the size (for example, lateral length) of the micro-component 220 is gradually reduced, the capillary force F31, the adhesion fixing force F32, and the holding force F33 will gradually gain control over the influence of the micro-component 220 (compared to the effect applied to the micro-component 220 other He power). In addition, if the lateral length of the micro-component 220 is too large, gravity needs to be considered, which is undesirable for implementing some specific embodiments disclosed in this disclosure. In the above specific embodiment, due to the size effect of the micro-component 220 (that is, the smaller lateral length), at least one of the capillary force F31, the adhesion fixing force F32, and the gripping force F33 is greater than the adhesion force F2.

More specifically, the force applied to the micro-component 220 having a lateral length within the range mentioned in these specific embodiments will follow the following inequality:

F11<F2<F31............................................. ............(1)

F11<F2<F32............................................. ............(2)

F11<F2<F33............................................. ............(3)

F11<F2<F34............................................. ............(4)

F12<F2<F31............................................. ............(5)

F12<F2<F32............................................. ............(6)

F12<F2<F33............................................. ............(7)

F12<F2<F34............................................. ............(8)

The left side of inequalities (1) to (8): F11<F2 and F12<F2 can be satisfied by selecting a suitable combination of materials for the adhesive layer 230 and the surface of the grip area 242 in contact with the micro-component 220.

Table 1 lists the various forces mentioned so far:

Generally, when the lateral length of the micro-component 220 changes, the adhesion force F1 per unit area (including the values F11 and F12) and the adhesion force F2 per unit area do not change. In some embodiments, after the transfer head 240 contacts the micro-component 220, the speed at which the transfer head 240 moves upward and away from the carrier substrate 210 can be used to additionally modify the adhesion force F2. The faster the speed, the greater the adhesion force F2. In this way, the adhesive transfer head 240 can be used to implement the above transfer process. The complicated circuit design or mechanical design of the transfer head operated by electrostatic force, vacuum force, mechanical force or any combination thereof can be omitted. The adhesive transfer head 240 can complete the transfer process and reduce the cost of the process.

In the above-mentioned specific embodiment supported by FIGS. 1 to 7B, after some micro-elements 220 are placed on the receiving substrate 260, the micro-elements 220 are capillary force generated by the liquid layer 250 between the micro-elements 220 and the conductive pad 262 F31. After the evaporation, the adhesion and fixing force F32 generated between the micro-component 220 and the conductive pad 262, the gripping force F33 generated by the frozen liquid layer 250, and/or the transfer head, the micro-component, the liquid layer and the receiving substrate The combination is heated to form an adhesive force F34 clamping between the micro-component 220 and the receiving substrate 260, and then the micro-component 220 is separated from the transfer head 240 and transferred to the receiving substrate 260. In this way, the adhesive transfer head 240 without complicated circuit design can complete the transfer process due to the presence of the liquid layer 250, and reduce the process cost.

In short, a method for transferring micro-components from a carrier substrate to a receiving substrate by means of an adhesive transfer head is provided. Therefore, the transfer process is simplified by a simple transfer mechanism.

The above are only the preferred embodiments of the present disclosure, and do not limit the disclosure in any form. Although the present disclosure has been disclosed in the preferred embodiments as above, it is not intended to limit the disclosure. Anyone familiar with the profession Those skilled in the art, without departing from the scope of the technical solution of the present disclosure, can use the technical content of the above invention to make slight changes or modification into equivalent embodiments with equivalent changes, provided that the content of the technical solution of the present disclosure is not deviated from the content of the technical solution of the present disclosure, according to this disclosure Any simple modifications, equivalent changes and modifications made to the above embodiments by technical essence still fall within the scope of the technical solutions of the present disclosure.

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Claims (11)

A method of transferring micro-components includes: Preparing a carrier substrate with the micro component on the carrier substrate, wherein an adhesive layer is located between the carrier substrate and the micro component and contacts the carrier substrate and the micro component; Picking up the micro component from the carrier substrate by a transfer head; Forming a liquid layer on a receiving substrate; Placing the micro-component on the receiving substrate by the transfer head so that the micro-component is in contact with the liquid layer and is clamped by a capillary force; and The transfer head is moved away from the receiving substrate, so that the micro-element is separated from the transfer head and adhered and fixed to the receiving substrate. The method of claim 1, wherein the micro-component is adhered to the adhesive layer by a first adhesive force, the micro-component is adhered to the transfer head by a second adhesive force, and the capillary force is greater than the first The adhesive force and the second adhesive force enable the micro-component to be separated from the transfer head and adhered and fixed to the receiving substrate when the placement is performed. The method according to claim 2, wherein the first adhesive force and the second adhesive force include Van der Waals force. The method according to claim 2, wherein the second adhesive force is greater than the first adhesive force. The method according to claim 1, wherein the lateral length of the micro device is less than or equal to about 50 microns. The method according to claim 1, wherein the method further comprises: The liquid layer is evaporated before the micro component is separated from the transfer head, so that the micro component is attached to a conductive pad of the receiving substrate and electrically contacts the conductive pad, wherein the force of the micro component to the conductive pad It is the adhesion and fixation force generated after this evaporation. The method according to claim 6, wherein the micro-device includes an electrode thereon, and the micro-device is attached to the conductive pad via the electrode and electrically contacts the conductive pad. The method of claim 6, wherein the micro-component is adhered to the adhesive layer by a first adhesive force, the micro-component is adhered to the transfer head by a second adhesive force, and the adhesion fixing force is greater than the first adhesive force An adhesive force and the second adhesive force enable the micro component to be separated from the transfer head and adhered and fixed to the receiving substrate when the placement is performed. The method according to claim 6, wherein an area of the conductive pad is less than or equal to about 1 square millimeter. The method according to claim 1, wherein the method further The steps include: The temperature of the receiving substrate is lowered before the transfer head is moved away from the receiving substrate, so that the liquid layer is frozen. The method according to claim 1, wherein the method further comprises: Before the transfer head is moved away from the receiving substrate, a combination of the transfer head, the micro component, the liquid layer, and the receiving substrate is heated, so that a bonding force between the micro component and the receiving substrate is applied to the micro component A bond is formed with the receiving substrate.

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