Method of transferring a thin film device

Abstract

The present disclosure provides a method for transferring a thin film device, comprising: using a water film previously constructed on a transfer end of a water storage tube to adsorb a thin film device previously placed on a super-hydrophobic substrate, wherein the adsorption force between the water storage tube and the water film is greater than the adsorption force between the super-hydrophobic substrate and the water film; and attaching the thin film device adsorbed by the water film to a target bonding site on a substrate to be transferred, so that the thin film device is transferred from the water film to the target bonding site, wherein the bonding site is previously covered with a layer of conductive medium, and the adsorption force between the conductive medium and the thin film device is greater than the adsorption force between the water film and the thin film device.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of flexible electronic device integration, and in particular, to a method for transferring a thin film device. BACKGROUND

[0002] In recent years, flexible electronic devices have developed rapidly, greatly improving the degree of interaction and integration between human life and intelligent electronics. However, the working efficiency of existing flexible organic electronic elements such as OLEDs is still inferior to that of traditional inorganic LEDs prepared on sapphire substrates. Therefore, the main development direction of flexible electronics at this stage is to miniaturize rigid elements and combine them with flexible substrates through heterogeneous integration to achieve the flexibility of electronic devices.

[0003] Under the background of existing semiconductor process technology, it is not difficult to prepare electronic elements made of inorganic materials to micron level in size and thickness. The key problem is that the Young's modulus of the device is usually above GPa, and the device is easily damaged during the process of transferring and printing a single device to the circuit substrate. The most representative method in the existing method is to prepare a PDMS elastic stamp with a feature size comparable to the size of the device to be transferred by a semiconductor-compatible process, and to pick up the device by the viscosity of the PDMS. However, in this method, the solid PDMS directly interacts with the rigid thin film device, which may cause damage to the rigid thin film device due to excessive force. In addition, the adhesion between the stamp and the device to be transferred is controlled by changing the speed of the stamp during the transfer process, which is complicated and not conducive to practical application. SUMMARY

[0004] In view of the above problems, the present disclosure provides a method for transferring a thin film device to at least partially solve the above technical problems.

[0005] To solve the above technical problems, a method for transferring a thin film device is provided, comprising:

[0006] A water film is constructed in advance at the transfer end of the water storage pipe, and the thin film device is adsorbed on the super-hydrophobic substrate in advance, wherein the adsorption force between the water storage pipe and the water film is greater than the adsorption force between the super-hydrophobic substrate and the water film.

[0007] The thin film device adsorbed by the water film is attached to the target bonding site on the substrate to be transferred, so that the thin film device is transferred from the water film to the target bonding site, wherein the target bonding site is pre-coated with a layer of conductive medium, and the adsorption force between the conductive medium and the thin film device is greater than the adsorption force between the water film and the thin film device.

[0008] In one embodiment, the transfer end is the lower end of the water storage pipe, and the method for transferring a thin film device further comprises:

[0009] a water column of a predetermined length is pre-adsorbed by the water storage tube, and the water column is located at the upper end of the water storage tube;

[0010] a water film is obtained by dipping water at the lower end face of the water storage tube transfer end;

[0011] wherein the water column of the predetermined length is less than the length of the water storage tube.

[0012] In one embodiment, a thin film device pre-positioned on the super-hydrophobic substrate is adsorbed by the water film pre-constructed at the water storage tube transfer end, comprising:

[0013] The angle of the lower end face of the water storage tube transfer end is adjusted so that the thin film device pre-positioned on the super-hydrophobic substrate is adsorbed by the water film in the case that the water film of the transfer end is parallel to the thin film device on the super-hydrophobic substrate.

[0014] In one embodiment, the thin film device adsorbed by the water film is attached to a target bonding site on the substrate to be transferred, comprising:

[0015] The position of the lower end face of the water storage tube transfer end is adjusted so that the thin film device adsorbed by the water film is attached to the target bonding site on the substrate to be transferred in the case that the thin film device is aligned with the target bonding site.

[0016] In one embodiment, the angle or position of the lower end face of the water storage tube transfer end is adjusted by a high-precision three-dimensional displacement regulator.

[0017] In one embodiment, the water storage tube is a capillary tube, wherein the capillary tube has a flat end face; and the thin film device is a rigid thin film device.

[0018] In one embodiment, the surface area of the rigid thin film device is less than the effective area of the transfer end.

[0019] In one embodiment, a conductive medium is coated on the target bonding site according to the size of the conductive pad on the thin film device.

[0020] In one embodiment, further comprising, after the thin film device is transferred from the water film to the target bonding site:

[0021] The conductive pad on the thin film device is welded with the conductive medium pre-coated on the target bonding site by post-baking or reflow soldering.

[0022] In one embodiment, a single polished silicon wafer is assembled by self-assembly of perfluorooctyltrichlorosilane to obtain a super-hydrophobic substrate.

[0023] As can be seen from the above technical solutions, the method for transferring a thin film device provided by the present disclosure has at least one of the following beneficial effects:

[0024] (1) In the embodiment of the present disclosure, a water film is constructed at the transfer end of the water storage pipe, and then the thin film device is transferred. Compared with the traditional transfer method, the water film uses the viscosity of surface tension to adsorb the thin film device, and the water film has very low elastic modulus and will not be extruded with the thin film device, so as to cause damage to the thin film device, and lossless transfer can be realized.

[0025] (2) In the embodiment of the present disclosure, the water film is constructed at the transfer end of the water storage pipe, and then the thin film device is transferred. In the transfer process, with the self-evaporation of the water film in the environment, the adsorption force between the water film and the thin film device gradually decreases. In the case that the thin film device is bonded and attached to the target bonding site, the adsorption force between the conductive medium pre-covered on the target bonding site and the thin film device is greater than the adsorption force between the water film and the thin film device, so as to realize the separation of the thin film device and the water film. The cumbersome operation of precisely controlling the pickup speed and then controlling the adhesion force between the stamp and the device in the traditional transfer process is avoided, and the operation is more convenient.

[0026] (3) In the embodiment of the present disclosure, the water storage pipe is selected as the bearing tool for transfer, compared with the traditional transfer tool, the special preparation of the layout and the cumbersome and time-consuming semiconductor process processing are saved, the price is low, and it is easy to obtain. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is the structure diagram of the water storage pipe after the water film is constructed in the embodiment of the present disclosure.

[0028] Fig. 2(a) is a front view of the transfer end adsorbing the thin film device in the embodiment of the present disclosure.

[0029] Fig. 2(b) is a view of A of the transfer end adsorbing the thin film device in Fig. 2(a) in the embodiment of the present disclosure.

[0030] Fig. 3(a) is a front view of the substrate to be transferred after covering the conductive medium in the embodiment of the present disclosure.

[0031] Fig. 3(b) is a top view of the substrate to be transferred after covering the conductive medium in the embodiment of the present disclosure.

[0032] Fig. 4(a) and Fig. 4(b) are operation schematic diagrams of transferring array thin film devices by using a water film in the embodiment of the present disclosure.

[0033] BRIEF DESCRIPTION OF DRAWINGS

[0034] 1: water storage pipe;

[0035] 11: water column;

[0036] 12: air column;

[0037] 13: transfer end;

[0038] 14: water film;

[0039] 2: thin film device;

[0040] 21: conductive pad;

[0041] 3: substrate to be transferred;

[0042] 31: target bonding site;

[0043] 32: conductive medium. DETAILED DESCRIPTION

[0044] In order to make the objects, technical solutions, and advantages of the present disclosure clearer, the following will be further described in detail with specific embodiments and with reference to the drawings.

[0045] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. However, it will be apparent to one skilled in the art that one or more embodiments can be practiced without these specific details. In addition, in the following description, descriptions of well-known structures and techniques have been omitted to avoid unnecessarily obscuring the concept of the present disclosure.

[0046] The terms used herein are merely used to describe specific embodiments and are not intended to limit the present disclosure. The terms "include", "comprise" and the like used herein indicate the presence of the described features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0047] All terms used herein (including technical and scientific terms) have meanings commonly understood by one of ordinary skill in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having meanings consistent with the context of the present specification, and should not be interpreted in an idealized or overly formal manner.

[0048] In the case of using expressions such as "at least one of A, B, and C", it generally means one or more of A, B, and C, unless it is specifically stated otherwise. In the case of using expressions such as "at least one of A, B, or C", it generally means one or more of A, B, or C, unless it is specifically stated otherwise. In the case of using expressions such as "at least one of A, B, and / or C", it generally means one or more of A, B, and / or C, unless it is specifically stated otherwise.

[0049] The main development direction of flexible electronics at present is to miniaturize rigid elements, combine with flexible substrates through heterogeneous integration, and realize the flexibility of electronic devices. However, the Young's modulus of thin film devices is usually above GPa, and the existing transfer printing method often involves a cumbersome process of regulating and controlling the adhesion between the transfer head and the thin film device to be transferred during the process of transferring and printing the thin film device to the circuit substrate, and it is very easy to cause damage to the thin film device, resulting in low yield and unsatisfactory transfer printing effect.

[0050] Therefore, the present disclosure provides a method for transferring a thin film device.

[0051] The method for transferring a thin film device according to the present disclosure comprises the following steps:

[0052] Step S1: using a water film constructed in advance at the transfer end of a water storage pipe, adsorbing a thin film device pre-placed on a super-hydrophobic substrate, wherein the adsorption force between the water storage pipe and the water film is greater than the adsorption force between the super-hydrophobic substrate and the water film;

[0053] Step S2: attaching the thin film device adsorbed by the water film to a target bonding site on a substrate to be transferred, so that the thin film device is transferred from the water film to the target bonding site, wherein the target bonding site is pre-coated with a layer of conductive medium, and the adsorption force between the conductive medium and the thin film device is greater than the adsorption force between the water film and the thin film device.

[0054] According to the method for transferring the thin film device, the water film is constructed by using the transferring end of the water storage tube, and then the thin film device previously placed on the super-hydrophobic substrate is transferred by using the water film. The water film uses the viscosity of the surface tension to adsorb the thin film device, and the water film has a very low elastic modulus and does not extrude the thin film device, so that the thin film device is transferred without damage. The water film evaporates in the air, and the adsorption force of the water film on the thin film device gradually decreases, which is beneficial to the separation between the thin film device and the water film, and avoids the complicated operation of precisely controlling the pickup speed and the adhesion force between the stamp and the device in the traditional transfer process. The water storage tube is a capillary tube, which can be used to transfer the micro-rigid thin film device. The inner diameter of the capillary tube can be customized according to the size of the thin film device. The size of the water film constructed is equivalent to the size of the thin film device, so that the compact and multi-site micro-thin film device transfer integration can be realized.

[0055] Figure 1 Figure 1 is a structure diagram of the water storage tube after the water film is constructed in the embodiment of the present disclosure; Figure 2(a) is a front view of the transferring end of the water storage tube adsorbing the thin film device in the embodiment of the present disclosure; Figure 2(b) is a view of A of the transferring end of the water storage tube adsorbing the thin film device in Figure 2(a); Figure 3(a) is a front view of the substrate to be transferred after covering the conductive medium in the embodiment of the present disclosure; and Figure 3(b) is a top view of the substrate to be transferred after covering the conductive medium in the embodiment of the present disclosure.

[0056] As shown in Figure 1 , Figure 2(a), Figure 2(b), Figure 3(a), and Figure 3(b), in step S1 of the method for transferring the thin film device, the water film 14 is constructed on the transferring end 13 of the water storage tube 1 in advance, and the technical principle of adsorbing the thin film device 2 previously placed on the super-hydrophobic substrate is that, because the super-hydrophobic substrate has a small adsorption force on water, the thin film device is placed on the super-hydrophobic substrate in advance, so that the adsorption force of the water film on the thin film device is greater than the adsorption force of the super-hydrophobic substrate on the water film, and the thin film device can be smoothly picked up by the water film during the adsorption of the water film.

[0057] According to the embodiment of the present disclosure, the transferring end 13 is the lower end of the water storage tube 1, and the method for transferring the thin film device further comprises:

[0058] A water column 11 of a predetermined length is adsorbed by the water storage tube 1 in advance, and the water column 11 is located at the upper end of the water storage tube 1;

[0059] The water film 14 is obtained by dipping water at the lower end surface of the transferring end 13 of the water storage tube 1;

[0060] The water column of predetermined length is shorter than the length of the water storage tube. A certain length of air column 12 is retained at the lower end of the water storage tube so that when the lower end face of the transfer end of the water storage tube is wetted, the air column inside the water storage tube generates pressure and capillary suction to balance each other. Therefore, capillary action cannot occur at the transfer end, and a water film is only formed at the lower end face of the transfer end.

[0061] Through the embodiments of this disclosure, thin film devices are transferred by constructing a water film at the transfer end of the water storage pipe. The water film evaporates on its own in the air, and the adsorption force on the thin film device gradually decreases, which is beneficial to the subsequent separation between the thin film device and the water film. This avoids the cumbersome operation of finely controlling the pick-up speed and thus controlling the adhesion between the stamp and the device in the traditional transfer process.

[0062] According to embodiments of this disclosure, single-layer silicon wafers are assembled by a self-assembly method using perfluorooctyltrichlorosilane to obtain a superhydrophobic substrate.

[0063] According to embodiments of this disclosure, a capillary tube can be selected as the water storage tube for transferring micron-scale micro-thin film devices. The capillary tube has a flat end face, and the thin film device is a rigid thin film device.

[0064] According to embodiments of this disclosure, the surface area of ​​the rigid thin film device is smaller than the effective area of ​​the transfer end, so that the water film can completely encapsulate the thin film device and use the surface tension of the water film to adsorb the thin film device.

[0065] According to an embodiment of this disclosure, the effective area of ​​the transfer end is the area formed by the inner diameter of the lower end face of the water storage pipe.

[0066] Figure 4 is a flowchart illustrating the steps of using a water film transfer array thin film device in an embodiment of this disclosure.

[0067] As shown in Figure 4, in step S2 above, the thin film device adsorbed by the water film is attached to the target bonding site 31 on the substrate to be transferred 3, so that the thin film device is transferred from the water film to the target bonding site. When the thin film device is attached to the target bonding site on the substrate to be transferred, the adsorption force between the water film and the thin film device will gradually decrease because the water film evaporates in the air. Therefore, the adsorption force between the conductive medium and the thin film device is greater than the adsorption force between the water film and the thin film device, thereby achieving the separation of the thin film device from the water film and transferring the thin film device to the substrate to be transferred.

[0068] According to embodiments of this disclosure, the inner diameter of the water storage pipe can be customized according to the size of the thin film device, as shown in Figure 4, so that the effective working area of ​​the transfer end is comparable to the surface area of ​​the thin film device. When the thin film device adsorbed by the water film is attached to the target bonding site on the substrate to be transferred, it does not affect other thin film devices that have been transferred to the substrate to be transferred, thus realizing the transfer of the array thin film device.

[0069] According to an embodiment of the present disclosure, the two end faces of the capillary are polished by means of polishing with optical fiber abrasive paper, and burrs and irregular protrusions at the two ends of the capillary are removed to obtain a capillary with flat end faces.

[0070] By means of the embodiment of the present disclosure, the water storage tube selects a cheap capillary to transfer a micron-level micro-thin film device. The inner diameter of the water storage tube can be customized according to the size of the thin film device, so that the size of the water film constructed is comparable to the size of the thin film device, and the effective action area of the transfer end is limited to an area range comparable to the surface area of the thin film device. In the case that the thin film device absorbed by the water film is attached to the target bonding site on the to-be-transferred substrate, it will not affect other thin film devices that have been transferred to the to-be-transferred substrate on the to-be-transferred substrate, and compact and multi-site micro-thin film device transfer integration can be realized.

[0071] According to an embodiment of the present disclosure, specifically, the water film constructed in advance at the transfer end of the water storage tube is used to absorb the thin film device placed in advance on the super-hydrophobic substrate, which further comprises:

[0072] The angle of the lower end face of the transfer end of the water storage tube is adjusted by means of a high-precision three-dimensional displacement adjuster, so that the water film at the transfer end is parallel to the thin film device on the super-hydrophobic substrate, and the thin film device placed in advance on the super-hydrophobic substrate is absorbed by the water film.

[0073] According to an embodiment of the present disclosure, specifically, the thin film device absorbed by the water film is attached to the target bonding site on the to-be-transferred substrate, which further comprises:

[0074] The position of the lower end face of the transfer end of the water storage tube is adjusted by means of a high-precision three-dimensional displacement adjuster, so that the thin film device absorbed by the water film is aligned with the target bonding site on the to-be-transferred substrate, and the thin film device is attached to the target bonding site.

[0075] According to an embodiment of the present disclosure, the above-mentioned method of transferring a thin film device further comprises, after the thin film device is transferred from the water film to the target bonding site:

[0076] By means of post-baking or reflow soldering, the conductive pads on the thin film device are soldered with the conductive medium pre-coated on the target bonding site. The conductive medium 32 can be solder or silver paste, which can be coated on the target bonding site 31 by means of evaporation or spot coating according to the size of the conductive pads 21 on the thin film device.

[0077] According to the embodiment of the present disclosure, in the case that the thin film device adsorbed by the water film is attached to the target bonding site, the conductive medium is in a molten state, so as to utilize the wettability between the conductive medium and the conductive pad of the thin film device being less than the wettability between the water film and the thin film device, so that the adsorption force of the conductive medium to the thin film device is greater than the adsorption force of the water film to the thin film device, to realize the separation between the thin film device and the water film.

[0078] The technical solutions of the present disclosure are further explained and described below by specific embodiments in conjunction with the drawings. It should be noted that the following specific embodiments are only used as examples, and the protection scope of the present disclosure is not limited thereto.

[0079] The water film construction step: first, a predetermined length of water column is adsorbed by the upper end of the capillary tube, and a certain length of air column is reserved at the lower end of the capillary tube, wherein the lower end of the capillary tube is the transfer end. After the upper end of the capillary tube is fixed on the high-precision three-dimensional displacement adjuster by clamps or glue, the transfer end of the capillary tube is dipped in water, and due to the balance of the pressure generated by the certain length of air column reserved at the lower end of the capillary tube and the capillary suction, the transfer end of the capillary tube cannot be capillary, and a water film is formed at the transfer end.

[0080] The adsorption step: the angle of the lower end face of the transfer end of the capillary tube after the water film is constructed is adjusted by the high-precision three-dimensional displacement adjuster, so that in the case that the lower end face of the transfer end is parallel to the thin film device previously placed on the super-hydrophobic substrate, the water film constructed by the transfer end contacts the thin film device previously placed on the super-hydrophobic substrate, and the thin film device is completely wrapped by the water film through the observation of the observation mirror, and the thin film device is adsorbed by the surface tension of the water film, then the capillary tube is lifted by the high-precision three-dimensional displacement adjuster, and the adsorption of the water film constructed by the transfer end to the thin film device is completed.

[0081] The release step: as shown in FIG. 4, the transfer substrate contains four mutually perpendicular metal track lines in the horizontal and vertical directions respectively, which are buried in the insulating layer at different depths, so as to adjust the position of the lower end face of the transfer end of the capillary tube after the water film is constructed by the high-precision three-dimensional displacement adjuster, in the case that the thin film device adsorbed by the water film is aligned with the target bonding site on the transfer substrate, the thin film device adsorbed by the water film is accurately attached to the conductive medium in a molten state previously covered on the target bonding site, and since the wettability between the conductive medium and the conductive pad of the thin film device is less than the wettability between the water film and the thin film device, the adsorption force of the conductive medium to the thin film device is greater than the adsorption force of the water film to the thin film device, to realize the separation between the thin film device and the water film, and complete the release of the thin film device.

[0082] Finally, the conductive pads on the thin film devices are welded with the conductive medium pre-covered on the target bonding sites by post-baking or reflow soldering, as shown in FIG. 4, and the above steps are repeated multiple times to finally complete the transfer of the array thin film devices.

[0083] The above-described specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above-described specific embodiments are merely examples of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A method for transferring a thin film device, comprising: absorbing a thin film device previously placed on a super-hydrophobic substrate by a water film previously constructed at a transfer end of a water storage tube, wherein an absorption force between the water storage tube and the water film is greater than an absorption force between the super-hydrophobic substrate and the water film, the water storage tube has a flat end surface, the thin film device is a rigid thin film device, and a surface area of the rigid thin film device is less than an active area of the transfer end; attaching the thin film device absorbed by the water film to a target bonding site on a substrate to be transferred, so that the thin film device is transferred from the water film to the target bonding site, wherein the target bonding site is previously covered with a conductive medium, and an absorption force between the conductive medium and the thin film device is greater than an absorption force between the water film and the thin film device by self-evaporation of the water film in air.

2. The method of claim 1, wherein, The transfer end is a lower end of the water storage tube, and the method further comprises: absorbing a water column of a predetermined length by the water storage tube, wherein the water column is located at an upper end of the water storage tube; obtaining the water film by dipping water at a lower end surface of the transfer end of the water storage tube; wherein the water column of the predetermined length is less than a length of the water storage tube.

3. The method of claim 1, wherein, The absorbing the thin film device previously placed on the super-hydrophobic substrate by the water film previously constructed at the transfer end of the water storage tube comprises: adjusting an angle of the lower end surface of the transfer end of the water storage tube, so that the thin film device previously placed on the super-hydrophobic substrate is absorbed by the water film in a case that the water film at the transfer end is parallel to the thin film device on the super-hydrophobic substrate.

4. The method of claim 1, wherein, The attaching the thin film device absorbed by the water film to the target bonding site on the substrate to be transferred comprises: adjusting a position of the lower end surface of the transfer end of the water storage tube, so that the thin film device absorbed by the water film is attached to the target bonding site in a case that the thin film device is aligned with the target bonding site on the substrate to be transferred. 5.The method of claim 3 or 4, wherein: the angle or the position of the lower end surface of the transfer end of the water storage tube is adjusted by a high-precision three-dimensional displacement adjuster. 6.The method of claim 1, wherein: the water storage tube is a capillary tube.

7. The method of claim 1, wherein, further comprising: the conductive medium is covered on the target bonding site according to a size of a conductive pad on the thin film device.

8. The method of claim 1, wherein, further comprising, after the thin film device is transferred from the water film to the target bonding site: the conductive pad on the thin film device is welded with the conductive medium previously covered on the target bonding site by post-baking or reflow soldering.

9. The method of claim 1, wherein, further comprising: the single-polished silicon wafer is assembled by self-assembly of perfluorooctyltrichlorosilane to obtain the super-hydrophobic substrate.

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