JP2014146625A - Method for forming embedded electrode or wiring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method by which a pattern having no level difference between the top face of an electrode/wiring and the top face of a non-electrode/wiring portion on any base material, and a high quality electronic component obtained by the method.SOLUTION: A method for forming a pattern of an electrode or wiring embedded in an insulating ink film includes the steps of: forming an electrode or wiring pattern on a blanket; coating an insulating ink on the blanket and the pattern to form a film having a multilayer structure on the blanket; and transferring the obtained film having a multilayer structure from the blanket to an object.

Description

  The present invention relates to a method for manufacturing an electrode or a wiring, and more particularly to a method for manufacturing an electrode or a wiring embedded in an insulating film.

A device structure typified by a thin film transistor (TFT) has been produced by a method combining vacuum film formation and photolithography.
In recent years, a technique for forming a similar structure such as a TFT by using a printing method for these processes has been developed. The TFT fabrication process by full printing has not been put on the market so far, but as a powerful printing method for forming the structure, there are a micro contact printing method, a reverse transfer printing method, and an ink jet method.

FIG. 1A shows a bottom gate / bottom contact transistor most promising as a TFT structure. A source electrode or a gate electrode is formed on an insulating film 3 formed on a gate electrode 2 on a substrate 1 by a printing method. 2 shows an example in which a pattern 4 of a drain electrode (hereinafter referred to as an S / D electrode) is formed, in which (a) is a rectangular thin film and (b) is an S / D electrode pattern. (C) shows a case where the S / D electrode pattern has a kamaboko shape.
In the case of the conventional printing method, as shown in the figure, a step is generated in the S / D electrode pattern 4 and the insulating film 3 therebetween. Since the semiconductor layer 5 is formed on the step, if the step is large, the semiconductor layer 5 may break or a gap may be formed between the insulating film 3 as shown in FIG. is there.

  For the above reasons, it is necessary to make the S / D electrode pattern extremely thin in order to realize the TFT structure. For example, although printing methods such as gravure printing and screen printing have excellent characteristics from the viewpoints of economy and mass productivity, they are printing for thick films, and as shown in FIG. The step between the / D electrode pattern 14 and the insulating film 3 becomes too large, and it is very difficult to realize a TFT structure. Further, the S / D electrode pattern has a rectangular shape as shown in the S / D electrode pattern 14 of FIG. 1B or an S / D electrode pattern 24 of FIG. Since it takes various cross-sectional shapes such as a kamaboko shape as shown, characteristic variations between TFTs and malfunction of TFTs occur, which is a big issue for industrialization.

  On the other hand, there is a reverse transfer printing method (refer to Patent Documents 1 to 3) as a method for forming an extremely thin electrode / wiring. In this method, ink is applied thinly and evenly on a blanket with a soft resin such as silicone rubber as the outermost layer, and then a relief plate called a release plate is applied to the blanket to remove unnecessary ink in a relief plate shape. The printing is completed by transferring the necessary pattern remaining on the blanket to the object. However, this time, the electrode / wiring is an extremely thin film, so that there is a problem that disconnection is likely to occur.

  That is, the act of forming the electrode / wiring pattern on the insulating film itself hinders stable TFT formation and its operation.

In Patent Document 4, when a gate electrode is formed by a printing method, it is often formed thicker than when a gate electrode is formed using a vacuum apparatus or photolithography, and in order to reduce leakage current between the electrodes. Although the gate insulating film must also be thick, it is described that it is necessary to apply a high voltage to the gate electrode for driving the transistor. In this patent document, the surface of the substrate, the surface of the electrode pattern, Has been proposed to reduce the drive voltage by thinning the insulating film.
However, the method of this patent document is to embed an electrode material in a recess formed in the same shape as the electrode pattern on the surface of the base material, thereby forming an embedded electrode having the same height as the substrate surface. In addition to the need to form a recess in the substrate, there is a problem that the substrate to be used is limited to one that can form a recess.

JP-A-11-58921 JP 2009-265118 A JP 2007-144984 A JP 2006-186293 A

  The present invention has been made in view of such circumstances, and provides a method capable of forming a pattern having no step between the upper surface of the electrode / wiring and the upper surface of the non-electrode / wiring portion on any substrate. As a result, the object is to provide high-quality electronic components.

  As a result of intensive studies to achieve the above object, the present inventors formed an electrode / wiring pattern made of conductive ink on the blanket, and then insulated the entire blanket so as to cover the pattern on the blanket. It was found that an electrode / wiring pattern embedded in an insulating film can be formed by forming a film and then transferring the electrode / wiring pattern together with the insulating film from a blanket to an object.

The present invention has been completed based on these findings, and according to the present invention, the following inventions are provided.
[1] A method of forming an electrode or wiring pattern embedded in an insulating ink film,
Forming an electrode or wiring pattern on the blanket;
Applying an insulating ink on the blanket and the pattern to form a film having a multilayer structure on the blanket;
And transferring the obtained film having a multilayer structure from the blanket to an object.
[2] The pattern forming method as described in [1], wherein the electrode or wiring pattern is formed by a printing method.
[3] The pattern forming method according to [1], wherein the electrode or wiring pattern is formed by pressing and releasing a relief plate against a conductive ink film applied on the blanket.
[4] A method for producing a thin film transistor, wherein an electrode is formed by the pattern forming method according to any one of [1] to [3].
[5] The method for producing a thin film transistor according to [4], wherein the electrode is a source / drain electrode.

  Conventionally, in the electronic device manufacturing technology by printing, a method of forming a film one by one has been used, so that a step is generated between the electrode / wiring pattern portion and the lower layer. According to the present invention, the electrode / wiring pattern is insulated. As a result, it is possible to form a film without a step between the electrode / wiring pattern and the insulating film. In addition, when the present invention is applied to the manufacture of a TFT, it is possible to form a film without a step between the S / D electrode pattern and the insulating film, so that the thickness of the subsequent semiconductor layer can be reduced, and the S / D Since the contact point between the D electrode pattern and the semiconductor layer is flat, the transistor characteristics are expected to be improved. Further, no step due to the thickness of the electrode / wiring is generated on the outermost surface of the electrode / wiring pattern forming layer, and therefore the thickness and cross-sectional shape of the embedded electrode / wiring do not pose a problem in performing the post-process. Accordingly, the degree of freedom of the printing method used as the electrode / wiring forming method is increased, and a printing method (for example, screen printing or gravure printing) suitable for a thick film, which has been difficult in the past, can be used as a method for forming a TFT electrode.

The figure which shows the structure at the time of producing the S / D electrode pattern of bottom gate and bottom contact type TFT by the conventional printing method. Schematic which shows the process of embedding an electrode and wiring in an insulating film by the method of this invention. 1 is a conceptual diagram of a bottom gate / bottom contact TFT formed by the method of the present invention. FIG. Schematic which shows the process of the Example which forms an S / D electrode pattern in an insulating film. The cross-sectional scanning electron microscope image of the embedded S / D electrode pattern formed by the method of the present invention. The figure which shows the enlarged image of the embedding S / D electrode pattern shown in FIG.

Hereinafter, the present invention will be described in more detail.
FIG. 2 is a schematic diagram showing the steps of the method of the present invention, where (a) shows an electrode / wiring pattern formed on the blanket, and (b) shows an insulation on the blanket on which the electrode / wiring pattern is formed. The figure which formed the film | membrane, (c) is a figure which shows a mode that the electrode and wiring pattern, and an insulating film are transcribe | transferred collectively to a target object, (d) has completed transfer of the electrode, wiring pattern, and an insulating film to a target object FIG.

  First, as shown in FIG. 2A, an electrode / wiring pattern 54 is formed on a blanket 56 using a conductive ink. Next, as shown in FIG. 2B, an insulating film 53 is uniformly formed on the blanket 56 using an insulating film ink. By this step, a multilayer film composed of the electrode / wiring pattern 54 and the insulating film 53 formed on the blanket 56 can be formed. Next, as shown in FIG. 2C to FIG. 2D, the electrode / wiring pattern 54 is transferred from the blanket 56 to the object 51 together with the insulating film 53, so that the electrode / wiring embedded in the insulating film 53 is transferred. A pattern 54 is formed.

  In the blanket used in the present invention, an electrode / wiring pattern formed from the above-described conductive ink and an insulating film made of an insulating film ink can be formed uniformly, and good peeling at the time of batch transfer to an object For example, a blanket having silicone rubber as the outermost layer can be suitably used.

As the conductive ink to be used, an ink containing metal fine particles, for example, an ink in which silver nanoparticles or copper nanoparticles are dispersed is preferably used, but a solution-based ink having a metal precursor or a conductive polymer may also be used.
Also, the method for forming the electrode / wiring pattern is not particularly limited. For example, it may be formed by various printing methods or after it is uniformly applied with conductive ink and formed into a predetermined shape. A method of removing unnecessary portions using a punching plate may be used.

The insulating film ink to be used is not particularly limited as long as it can be uniformly applied on the blanket and has an insulating property. For example, a resin solution such as polyimide resin, polyvinyl phenol resin, or epoxy resin is preferably used.
The solvent used in the resin solution can dissolve the resin that forms the insulating film, can be uniformly applied on the blanket, and a suitable amount of solvent is lost in the time required from application to transfer so that good transfer to the object is possible. Anything to do. At this time, an ink adjusting agent such as a surfactant or a viscosity adjusting agent may be contained, or a plurality of solvents may be used. However, those that significantly deform the blanket by swelling, those that dissolve the blanket surface by chemical reaction, and those that dissolve or redisperse the conductive ink film described above are unsuitable.

  Moreover, as a method for forming the insulating film, it is sufficient if uniform coating can be performed. Therefore, in addition to the spin coating method, a coating method using a slit coater, an applicator, a bar coater, or the like can be used.

If necessary, the transferred insulating film is cured by heating and baking to complete.
In FIG. 2, the blanket 56 and the object 51 are shown as sheet-like objects. However, for example, the shape of the blanket or the printing object is not limited to a sheet-like object, but may be a roll-like object. It may be a sheet or a sheet wound on a roll.

  FIG. 3 is a diagram for comparing the structure of FIG. 1 formed by the prior art with the structure that can be achieved by the present invention. In the bottom gate / bottom contact type TFT, the substrate according to the method of the present invention described above is used. An example of a TFT in which an S / D electrode pattern embedded in an insulating film 103 is formed on a gate electrode 102 on 101 and a semiconductor layer 105 is formed thereon is shown. When the / D electrode pattern is a rectangle and a thin film, (b) shows the case where the S / D electrode pattern is a rectangle and a thick film, and (c) shows the case where the S / D electrode pattern is a kamaboko shape.

  As shown in FIG. 3A, the upper surface of the insulating film 103 and the upper surface of the S / D electrode pattern 104 are flush with each other formed by the method of the present invention. Therefore, according to the method of the present invention, as shown in FIG. 3B, even when the S / D electrode pattern 114 is formed as a thick film, it is formed on the S / D electrode pattern 114 and the insulating film 103. The problem that the semiconductor layer 105 is broken does not occur. Further, there is no problem even if the cross-sectional shape is broken as shown in the S / D electrode pattern 124 in FIG. In order to fabricate a TFT by full printing, it is necessary to form the above-mentioned multilayer structure after forming the gate electrode 102 on an insulating transfer material. The method of the invention can be used, or other conventional methods such as microcontact method, ink jet method, reverse printing method can be used.

  According to the present invention, the thickness of the semiconductor layer 105 can be reduced, and the contact point between the S / D electrode pattern 104 or the S / D electrode pattern 114 or S / D electrode pattern 124 and the semiconductor layer 105 is flat. Improvement is expected. Further, since no step due to the thickness of the electrode occurs on the outermost surface of the formation layer of the S / D electrode pattern 104, the S / D electrode pattern 114, or the S / D electrode pattern 124, the thickness and cross-sectional shape of the embedded electrode are There is no problem in carrying out the post-process. Therefore, the degree of freedom of the printing method used as the electrode / wiring forming method is increased, and a printing method suitable for a thick film, such as a screen printing method or a gravure printing method, which has been difficult in the past, can be used as the TFT electrode forming method.

  FIG. 3 shows a bottom gate / bottom contact type TFT that can be achieved by the present invention. However, the present invention is not limited to this, and the S / D electrode pattern embedded in the substrate-side insulating layer of the top gate / bottom contact type TFT and Even the gate electrode / wiring pattern embedded in the gate insulating film can be achieved by the present invention.

EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to this Example.
In this example, the S / D electrode pattern was formed in the insulating film using the method of the present invention. FIG. 4 is a schematic view showing the process.

  A pigment ink (nano silver ink) in which silver nanoparticles were dispersed was used as the conductive ink. Polyvinyl phenol ink was used as the insulating film ink. Silicone rubber was used as a blanket. As a method for forming the electrode pattern, a resist-extracted plate manufactured by Geomatic Co., Ltd. was used.

First, nano silver ink 257 was uniformly applied on silicone rubber blanket 256 by spin coating (FIG. 4A). Thereafter, an unnecessary portion was transferred to the punch using a resist punch, thereby forming an S / D electrode pattern 254 on the silicone rubber blanket 256 (FIG. 4B).
Next, an insulating film ink was uniformly applied on the silicone rubber blanket 256 by spin coating to form an insulating film 253 (FIG. 4C).
Next, the multilayer film composed of the S / D electrode pattern 254 and the insulating film 253 formed on the blanket 256 was transferred onto the oxide film 258 having a thickness of 300 nm formed on the silicon wafer 251 (FIG. 4D). . Finally, the film was cured by heating and baking in an oven to complete the film formation (FIG. 4E).

Scanning electron microscope images obtained by observing a cross section of the obtained multilayer film structure are shown in FIGS. FIG. 5 is an overall view, and FIG. 6 is an enlarged view of the embedded portion.
5 and 6 that the S / D electrode pattern 254 is embedded in the insulating film 253, and the step difference between the upper surfaces of the S / D electrode pattern 254 and the insulating film 253 is very small.

  In this embodiment, a p-type or n-type doped silicon wafer, which is a transfer material, can be used as the gate electrode. However, in producing a bottom gate / bottom contact type TFT by full printing, a gate is used. It is necessary to form the multilayer structure described above on the transfer material on which the electrode is formed. In this case, the method of the present invention can be used as a method for forming the gate electrode, or other conventional methods, for example, A micro contact method, an ink jet method, or a reverse printing method can also be used.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Gate electrode 3 Insulating film 4 S / D electrode pattern 5 Semiconductor layer 14 S / D electrode pattern 24 S / D electrode pattern 51 Substrate 53 Insulating film 54 Electrode / wiring pattern 56 Blanket 101 Substrate 102 Gate electrode 103 Insulating film 104 S / D electrode pattern 105 Semiconductor layer 114 S / D electrode pattern 124 S / D electrode pattern 251 Silicon wafer 253 Insulating film 254 S / D electrode pattern 256 Blanket 257 Nano silver ink 258 Silicon thermal oxide film

Claims (5)

A method of forming an electrode or wiring pattern embedded in an insulating ink film,
Forming an electrode or wiring pattern on the blanket;
Applying an insulating ink on the blanket and the pattern to form a film having a multilayer structure on the blanket;
And transferring the obtained film having a multilayer structure from the blanket to an object.   The pattern forming method according to claim 1, wherein the pattern of the electrode or the wiring is formed by a printing method.   The pattern forming method according to claim 1, wherein the electrode or wiring pattern is formed by pressing a relief plate against the conductive ink film applied on the blanket and releasing it.   An electrode is formed by the pattern forming method according to claim 1.   5. The method of manufacturing a thin film transistor according to claim 4, wherein the electrode is a source / drain electrode.

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