JP2011003668A - Method of transferring element and method of manufacturing electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of transferring an element, capable of simplifying a transfer process.SOLUTION: The method of transferring the element includes: a step of sticking a first substrate (S1a) having a first peeling layer (3a) and a first element layer (17a) disposed above the first peeling layer, and a second substrate (S1b) having a second peeling layer (3b) and a second element layer (17b) disposed above the second peeling layer on each other, so that the first element layer and second element layer face each other with intermediate layers (S2, 50a, and 50b) interposed; a first peeling step of peeling the first substrate from the first peeling layer; and a second peeling step of peeling the second substrate from the second peeling layer. Thus, the two element layers can be transferred through the simple processes by sticking the two substrates on each other with the intermediate layers interposed. Further, the two substrates (element layers) can be transferred using one intermediate layer. Furthermore, simultaneous irradiation with laser light becomes possible to simplify the peeling processes.

Description

  The present invention relates to an element transfer method and an electronic device manufacturing method, and more particularly to a technique used in a transfer process to a flexible substrate.

  In recent years, in the development of electro-optical devices such as liquid crystal devices, the use of flexible substrates has been studied because of the flexibility and impact resistance in addition to the reduction in size and weight of the devices.

  Since such a flexible substrate is inferior in heat resistance and solvent resistance to a glass substrate, it is difficult to form an element directly on the flexible substrate. In addition, due to its flexibility, it was necessary to devise handling during the manufacturing process.

  Therefore, a technique for transferring an element formed on a glass substrate to a flexible substrate is employed.

  For example, in the following Patent Document 1, a first separation layer (120) is provided on a substrate (100) that can transmit laser light in advance, and then a thin film device (140) such as a TFT is formed. A primary transfer body (180) is formed thereon via a second separation layer (160), primary transfer is performed by removing the substrate, and further, an adhesive layer (190) is interposed on the exposed lower surface of the thin film device. Then, after joining the secondary transfer body (200), a technique for performing secondary transfer by weakening the binding force of the second separation layer and removing the primary transfer body is disclosed.

JP-A-11-26733

  Although the above transfer technology is attracting attention as a technology that can form a semiconductor element such as a thin film transistor on an arbitrary substrate according to the use and convenience of various electronic devices, it improves the manufacturing yield of the device by simplifying the transfer process. Further improvements are desired, such as planning.

  A specific aspect of the present invention aims to provide a device transfer method capable of simplifying the transfer process.

  An element transfer method according to the present invention includes a first substrate having a first release layer and a first element layer disposed above the first release layer, a second release layer, and the second release layer. Bonding a second substrate having a second element layer disposed above the layer so that the first element layer and the second element layer are opposed to each other through an intermediate layer; A first peeling step for peeling the first substrate from the first peeling layer; and a second peeling step for peeling the second substrate from the second peeling layer.

  As described above, the two element layers can be transferred in a simple process by bonding the two substrates through the intermediate layer. In addition, it is possible to transfer two substrates (element layers) using one intermediate layer.

  Preferably, the first peeling step and the second peeling step are performed by simultaneously irradiating the first peeling layer and the second peeling layer with a laser. In this manner, by bonding two substrates through the intermediate layer, simultaneous laser irradiation can be performed, and the peeling process can be simplified.

  For example, the intermediate layer is a laminate of a first release sheet, a base material, and a second release sheet. For example, the intermediate layer is a release sheet having adhesive layers on both sides. Thus, you may use a base material and a peeling sheet.

  For example, the first release layer and the second release layer are made of amorphous silicon. As described above, amorphous silicon may be used as the release layer. Amorphous silicon is easily ablated by laser irradiation and is suitable for use as a release film.

  Preferably, after the first peeling step, a step of bonding a third substrate to the first element layer, and after the second peeling step, a step of bonding a fourth substrate to the second element layer. Have. The third substrate and the fourth substrate are flexible substrates. Moreover, it has the process of removing the said intermediate | middle layer after the bonding process of a said 3rd board | substrate and a 4th board | substrate.

  Thus, the transfer process can be efficiently performed by further bonding the two substrates and removing the intermediate layer. Further, the element layer can be easily and efficiently transferred onto the flexible substrate.

  An electronic device manufacturing method according to the present invention includes the above-described element transfer method. According to this method, an electronic device can be manufactured with a simple process.

It is sectional drawing which shows the transfer process (The element transfer method, the manufacturing method of a semiconductor device) of the thin film device of this Embodiment. It is sectional drawing which shows the transcription | transfer process of the thin film device of this Embodiment. It is sectional drawing which shows the transcription | transfer process of the thin film device of this Embodiment. It is sectional drawing which shows the transcription | transfer process of the thin film device of this Embodiment. It is sectional drawing which shows the application example 1 of the transcription | transfer process of the thin film device of this Embodiment. It is sectional drawing which shows the application example 3 of the transcription | transfer process of the thin film device of this Embodiment. It is sectional drawing which shows the application example 4 of the transcription | transfer process of the thin film device of this Embodiment. It is sectional drawing which shows the application example 4 of the transcription | transfer process of the thin film device of this Embodiment. It is a figure which shows the circuit structure of an active matrix substrate. It is a perspective view which shows electronic paper. It is a perspective view which shows the microcomputer formed on the flexible substrate.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same or related code | symbol is attached | subjected to what has the same function, and the repeated description is abbreviate | omitted.

  1 to 4 are cross-sectional views showing a thin film device transfer step (element transfer method, semiconductor device manufacturing method) according to the present embodiment. The transfer process, that is, the process of transferring the semiconductor element formed on the first substrate to the second substrate and further transferring to the third substrate will be described with reference to these drawings. Here, a thin film transistor (TFT) is illustrated and described as a semiconductor element.

1) TFT formation step As shown in FIG. 1A, release layers 3a and 3b are formed on a substrate S1a and a substrate S1b, respectively. The material of the substrates S1a and S1b is not particularly limited as long as it can withstand each process in the subsequent TFT (element) formation process. For example, a glass substrate can be used.

  Next, an amorphous silicon film is formed on each of the substrates S1a and S1b as a separation layer (separation layer, sacrificial layer, adhesion / peeling layer) 3a and 3b by a CVD (chemical vapor deposition) method. Other materials may be used as the release layers 3a and 3b. Further, not only a single layer but also a plurality of layers may be used.

  Next, TFTs (Ta, Tb) are formed on the release layers 3a, 3b. Although there is no particular limitation on the TFT formation process, the TFT can be formed by the following processes.

  As shown in FIG. 1B, a silicon oxide film is deposited on the release layers 3a and 3b by a CVD method to form base protective films 5a and 5b. Further, for example, after depositing an amorphous silicon film by the CVD method, this film is crystallized by irradiating with a laser to obtain a polycrystalline silicon film. Thereafter, patterning is performed to form island-shaped semiconductor films 7a and 7b. Next, on the semiconductor films 7a and 7b, for example, a silicon oxide film is deposited by a CVD method to form gate insulating films 9a and 9b. Next, on the gate insulating films 9a and 9b, for example, an aluminum (Al) film or the like is formed by a sputtering method and patterned to form the gate electrode 11. Next, using the gate electrode 11 as a mask, for example, impurities such as boron (B) or phosphorus (P) are ion-implanted to form the source and drain regions 7sd. The TFT (Ta, Tb) is formed by the above process.

  Next, for example, a silicon oxide film is deposited on the gate electrode 11 by a CVD method to form an interlayer insulating film 13, and then the interlayer insulating film 13 on the source and drain regions 7sd is etched to form contact holes. Next, an Al film, for example, is deposited on the interlayer insulating film 13 including the inside of the contact hole by sputtering and patterned to form source and drain lead lines 15a and 15b.

  Thereafter, a protective film may be formed on the source / drain lead wires 15a and 15b as necessary. Further, by repeating the deposition of the conductive film, the patterning, and the deposition of the interlayer insulating film, a multilayer wiring may be formed on the source and drain lead wirings 15a and 15b, and an element other than the TFT may be formed. .

  The layers in which these various elements and wirings are formed are referred to as element layers 17a and 17b. The element layers 17a and 17b are transferred layers.

2) First transfer step The element layers 17a and 17b of the two substrates S1a and S1b formed in the above steps are placed on the front surface (first surface) and back surface (second surface) of the intermediate substrate S2 via a release sheet. paste. The condition of the intermediate substrate S2 may be any substrate that can withstand the subsequent processes. For example, a glass substrate may be used in the same manner as the substrates S1a and S1b.

  The release sheet is not particularly limited as long as it is a sheet having an adhesive layer (adhesive layer) on at least one surface of the base material and can be peeled after the subsequent second transfer step, for example, FIG. The release sheet 50 shown in FIG.

  As shown in the figure, the release sheet 50 has a thermal release adhesive 53 and a release liner 55 sequentially laminated on the first surface of the polyester film substrate 51, and a pressure-sensitive adhesive 57 and a release liner 59 sequentially on the second surface. It has a stacked configuration.

  Two release sheets having the above-described configuration are prepared (50a, 50b) and attached to the substrates S1a, S1b (FIG. 2B). Specifically, the release liner 55 of the release sheet 50a is peeled off, and the heat release adhesive 53 is attached to the element layer 17a of the substrate S1a. Further, the release liner of the release sheet 50b is peeled off, and the heat release adhesive 53 is attached to the element layer 17b of the substrate S1b.

  Next, the release liner 59 of the release sheets 50a and 50b is peeled off, and the respective pressure-sensitive adhesives 57 are pressure-bonded to the front surface (first surface) and back surface (second surface) of the intermediate substrate S2 (FIG. 2C). In the above process, a release sheet having an adhesive on both sides is used, but a single-sided release sheet in which the pressure-sensitive adhesive 57 and the release liner 59 are omitted may be used. In this case, the polyester film base 51 may be bonded to the front and back surfaces of the intermediate substrate S2 using an adhesive or the like.

  Next, as shown in FIG. 3A, the laser is irradiated simultaneously on the front surface side and the back surface side of the intermediate substrate S2. That is, ablation is caused by irradiating a laser to the peeling layer (amorphous silicon film) 3a of the substrate S1a from below. Further, ablation is caused by irradiating the release layer (amorphous silicon film) 3b of the substrate S1b with laser from the upper side. Thereby, a crack arises in the inside of a peeling layer (3a, 3b) and an interface, and bond strength weakens.

  Next, as shown in FIG. 3B, the substrates S1 and S2 are peeled off, and the remaining peeling layers 3a and 3b are removed as necessary.

3) Second Transfer Step Next, as shown in FIG. 4A, the first surface of the plastic substrate S3a is bonded to the element layer 17a using the permanent adhesive layer 65a. Here, the support substrate S4a is bonded to the second surface of the plastic substrate S3a via the release layer 63a. Further, the first surface of the plastic substrate S3b is bonded to the element layer 17b using the permanent adhesive layer 65b. Here, the support substrate S4b is bonded to the second surface of the plastic substrate S3b via the release layer 63b.

  The supporting substrates S4a and S4b are not particularly limited as long as they can support the plastic substrates S3a and S3b. For example, glass substrates can be used. The plastic substrates S3a and S3b are flexible and can be made of, for example, a synthetic resin. Although there is no restriction | limiting in the material of peeling layer 63a, 63b, For example, you may use the above-mentioned amorphous silicon film. Moreover, although there is no restriction | limiting in the material of permanent adhesive 65a, 65b, For example, a thermosetting resin, an ultraviolet curable resin, etc. can be used.

  Next, the intermediate substrate S2 is removed. Specifically, after the release sheets 50a and 50b are heated to weaken the adhesiveness of the thermal release adhesive (53) in the release sheet, the release sheets 50a and 50b are made of plastic as shown in FIG. The substrates S3a and S3b are peeled off. Further, the support substrates S4a and S4b are peeled from the peeling layers 63a and 63b, whereby the transfer of the element layers 17a and 17b onto the plastic substrates S3a and S3b is completed (FIG. 4C).

  As described above, according to the present embodiment, since the element layers 17a and 17b are transferred to both surfaces of the intermediate substrate S2, primary transfer can be performed in a simple process by laser irradiation from the vertical direction. In addition, primary transfer of the two element layers (17a, 17b) can be performed with one intermediate substrate S2, and the amount of use of the intermediate substrate S2 can be reduced.

<Application example>
Each process of the above embodiment can be variously modified and applied. One example will be described below.

<Example 1>
For example, although the intermediate substrate S2 is used in the above embodiment (see FIG. 3A), the intermediate substrate may be omitted and the element layers 17a and 17b may be bonded to both surfaces of the release sheet.

  FIG. 5 is a sectional view showing an application example 1 of the transfer process of the thin film device of the present embodiment. Here, as shown in FIG. 5A, the thermal release adhesive 53A and the release liner 55 are sequentially laminated on the first surface of the polyester film substrate 51, and the thermal release adhesive 53B and the release liner 59 are also laminated on the second surface. A release sheet 50c having a configuration in which is sequentially laminated is used. The release liners 55 and 59 on both sides of the release sheet 50c are peeled off, and the element layer 17a of the substrate S1a and the element layer 17b of the substrate S1b are bonded (FIG. 5B). In the subsequent steps, the element layers 17a and 17b can be transferred in the same manner as the above-described steps described with reference to FIGS. 3 (A) to 4 (B).

<Example 2>
Moreover, in the said embodiment, although the heat peeling adhesive 53 was used for the peeling sheets 50a and 50b (refer FIG. 2 (A)), you may use an ultraviolet peeling adhesive. In this case, when the intermediate substrate S2 is removed, the release sheets 50a and 50b are irradiated with ultraviolet rays to weaken the adhesiveness of the ultraviolet release adhesive and release and remove it. Further, a water-soluble adhesive may be used instead of the pressure-sensitive adhesive. In this case, when removing the intermediate substrate S2, the adhesive is dissolved and removed by dipping in water.

<Example 3>
Further, without using the release sheets 50a and 50b, the element layers 17a and 17b may be bonded by applying the water-soluble adhesive 60 to the front and back surfaces of the intermediate substrate S2. FIG. 6 is a sectional view showing an application example 3 of the transfer process of the thin film device of the present embodiment. In this case, as shown in FIG. 6, the element layers 17a and 17b are bonded to the front and back surfaces of the intermediate substrate S2 via the water-soluble adhesive 60. In this case, when removing the intermediate substrate S2, the substrate shown in FIG. 6 is immersed in water and the water-soluble adhesive 60 is dissolved to peel off the intermediate substrate S2.

<Example 4>
When the intermediate substrate described in Example 1 is omitted, the transfer may be performed by the following process in order to ensure the rigidity of the substrate being transferred.

  7 and 8 are sectional views showing an application example 4 of the transfer process of the thin film device of the present embodiment.

  As shown in FIG. 7A, in a state where the element layers 17a and 17b are bonded through the release sheet 50c, laser is irradiated from the lower side to release the release layer (amorphous silicon film) 3a (see FIG. 7 (A)). B)). Next, as shown in FIG. 7C, after removing the remaining peeling layer 3a, a laminated substrate in which the supporting substrate S4a is bonded to the plastic substrate S3a through the peeling layer 63a is bonded to the element layer 17a and the permanent bonding layer 65a. Adhere using.

  Next, as shown in FIG. 8A, laser irradiation is performed from above to peel off the release layer (amorphous silicon film) 3b (FIG. 8B). Thereafter, after removing the remaining release layer 3b, the laminated substrate having the support substrate S4b bonded to the plastic substrate S3b through the release layer 63b is bonded to the element layer 17b using the permanent adhesive layer 65b (FIG. 8 ( C)).

  According to this process, since the support substrate S4a and the like are adhered to the element layer 17a side when the release layer (amorphous silicon film) 3b is peeled off, the rigidity is maintained and peeling is facilitated.

<Example 5>
In the above embodiment, the support substrates S4a and S4b are bonded to the plastic substrates S3a and S3b via the release layers 63a and 63b (see FIG. 4A), but the plastic substrates S3a and S3b are used. You may adhere | attach on the surface (1st surface, element formation surface) of element layer 17a, 17b directly. In this case, the plastic substrates S3a and S3b can be bonded by a simple process by laminating a plastic substrate material on the surface of the element layers 17a and 17b.

<Others>
In the above embodiment, the transfer to the plastic substrates S3a and S3b is performed as the secondary transfer. However, the present invention is not limited to the transfer to the plastic substrate, and is applied to the transfer method to various material base materials. Is possible.

  Further, in the above-described embodiment, the simultaneous irradiation of the laser has been described as an example. However, the use amount of the intermediate substrate S2 can be reduced by using both surfaces of the intermediate substrate S2, and the present invention has an effect. It is not limited to simultaneous laser irradiation.

  In the above embodiment, a semiconductor element such as a TFT is described as an example of an element in the transferred layer. However, the present invention is not limited to the semiconductor element, and the present invention can be applied to various element transfer techniques.

  As described above, the examples and application examples described through the above-described embodiment can be used in appropriate combination according to the application, or can be used with modification or improvement. The present invention is described in the above-described embodiment. It is not limited to.

<Description of electro-optical device and electronic device>
Although there is no restriction on the specific application location of the semiconductor element (TFT) transferred in the above embodiment and the like, the TFT is used as a pixel circuit or a drive circuit of an electro-optical device (display device), for example. FIG. 9 is a diagram showing a circuit configuration of the active matrix substrate. For example, in an active matrix liquid crystal device, as shown in FIG. 9, a TFT and a pixel electrode 70 are arranged at the intersection of a data line Y and a gate line X, one end of the TFT is a data line Y, and the other end is a pixel. The electrode 70 and its gate are connected to the gate line X. The data line Y is connected to the data line drive circuit 73, and the gate line X is connected to the gate line drive circuit 75. A TFT is also used as an element constituting such a drive circuit.

  Therefore, the semiconductor element (TFT) transferred in the above embodiment constitutes, for example, the pixel circuit or the drive circuit, and a liquid crystal, an electrophoretic capsule, an organic EL between the substrate S3 after the secondary transfer and the counter substrate. The display unit is configured by arranging (Electro-Luminescence) or the like.

  The display unit is an electronic device such as a mobile phone, a video camera, a roll-up television, a fax machine with a display function, a digital camera finder, a portable TV, an electronic notebook, an electric bulletin board, a display for advertisements, and electronic paper. It can be incorporated in equipment (electro-optical device).

  FIG. 10 is a perspective view showing electronic paper. An electronic paper 1000 illustrated in FIG. 10 includes a main body 1001 formed of a rewritable sheet having the same texture and flexibility as paper, and a display unit 1002. In such electronic paper 1000, the display unit 1002 includes the display unit as described above.

  FIG. 11 is a perspective view showing a microcomputer formed on a flexible substrate. The semiconductor element (TFT) transferred in the above embodiment can be applied not only to the electro-optical device but also to a microcomputer formed on a flexible substrate shown in FIG. 571 is a flexible substrate. For example, 573 is a RAM (random access memory), 575 is a CPU (central processing unit), 777 is an input / output circuit, and 579 is a solar cell.

  3a ... peeling layer, 3b ... peeling layer, 5a ... underlying protective film, 5b ... underlying protective film, 7a ... semiconductor film, 7b ... semiconductor film, 7sd ... source, drain region, 9a ... gate insulating film, 9b ... gate insulating film DESCRIPTION OF SYMBOLS 11 ... Gate electrode, 13 ... Interlayer insulation film, 15a ... Source, drain extraction wiring, 15b ... Source, drain extraction wiring, 17a ... Element layer, 17b ... Element layer, 50 ... Release sheet, 50a ... Release sheet, 50b ... Release sheet, 50c ... Release sheet, 51 ... Polyester film substrate, 53 ... Thermal release adhesive, 53A ... Thermal release adhesive, 53B ... Thermal release adhesive, 55 ... Release liner, 57 ... Pressure sensitive adhesive, 59 ... Release liner, 63a ... release layer, 63a ... release layer, 65a ... permanent adhesive layer, 65b ... permanent adhesive layer, 70 ... pixel electrode, 73 ... data line driving circuit, 75 ... gate Drive circuit, 571... Flexible substrate, 573... RAM, 575... CPU, 777 .. input / output circuit, 579... Solar cell, 1000 .. electronic paper, 1001 .. main body, 1002 ... display unit, S1a. ... intermediate substrate, S3a ... plastic substrate, S3b ... plastic substrate, S4a ... support substrate, S4b ... support substrate, T ... TFT, Ta ... TFT, Tb ... TFT, X ... gate line, Y ... data line

Claims (9)

A first substrate having a first release layer and a first element layer disposed above the first release layer, a second release layer, and a second element disposed above the second release layer Bonding a second substrate having a layer so that the first element layer and the second element layer are opposed to each other through an intermediate layer;
A first peeling step of peeling the first substrate from the first peeling layer;
A second peeling step of peeling the second substrate from the second peeling layer;
A method for transferring an element having the above. The first peeling step and the second peeling step include
The element transfer method according to claim 1, which is performed by simultaneously irradiating the first release layer and the second release layer with a laser.   The element transfer method according to claim 1, wherein the intermediate layer is a laminate of a first release sheet, a base material, and a second release sheet.   The element transfer method according to claim 1, wherein the intermediate layer is a release sheet having adhesive layers on both sides.   The element transfer method according to claim 1, wherein the first release layer and the second release layer are made of amorphous silicon. A step of bonding a third substrate to the first element layer after the first peeling step;
A step of bonding a fourth substrate to the second element layer after the second peeling step;
The element transfer method according to claim 1, comprising:   The element transfer method according to claim 6, wherein the third substrate and the fourth substrate are flexible substrates.   The element transfer method according to claim 6, further comprising a step of removing the intermediate layer after the step of bonding the third substrate and the fourth substrate.   The manufacturing method of the electronic device which has a transfer method of the element as described in any one of Claims 1 thru | or 8.

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