JP5534945B2 - Alkylsilane laminate, manufacturing method thereof, and thin film transistor - Google Patents

Description

  The present invention relates to an alkylsilane laminate and a method for producing the same. The present invention also relates to a thin film transistor, particularly a thin film transistor having an organic semiconductor film.

  In recent years, a semiconductor element typified by a thin film transistor (TFT) has been used for various applications such as a liquid crystal display device, a solar battery panel, and the like. A semiconductor element mainly used at present, particularly a semiconductor element using silicon as a semiconductor material, has a high manufacturing cost because a vacuum process such as CVD or sputtering is used at the time of manufacture. Moreover, it is difficult for such a semiconductor element to be a flexible element formed on a polymer film or the like from the viewpoint of process temperature.

  Applying organic semiconductor elements that can be fabricated by simple methods to active elements in fields that require low cost, such as lightweight and flexible elements that are expected to be put to practical use in the future, and RF-ID (Radio Frequency IDentification) Is being considered. The vacuum vapor deposition apparatus and coating apparatus used in the manufacture of such an organic semiconductor element are less expensive than the CVD apparatus and sputtering apparatus used in the manufacture of inorganic semiconductors. In the production of an organic semiconductor element, since the process temperature is low, the organic semiconductor element can be formed on a polymer film or paper.

  A thin film transistor using an organic semiconductor has a source electrode, a drain electrode, a gate electrode, a gate insulating film, and an organic semiconductor film on a substrate. In such a thin film transistor, a source electrode, a drain electrode, and a gate electrode are insulated from each other by a gate insulating film, and a current flowing through the organic semiconductor from the source electrode to the drain electrode is controlled by a voltage applied to the gate electrode.

  Here, the organic semiconductor film is an aggregate of a low molecular compound or a high molecular compound. As low molecular organic semiconductor materials, acene compounds (condensed polycyclic compounds condensed linearly) such as pentacene and thiophene oligomers are known. Further, regioregular polyalkylthiophene (P3AT), poly (fluorenebithiophene) (F8T2) and the like are known as polymer organic semiconductor materials.

  In order to obtain high switching characteristics in an organic thin film transistor, it is necessary to increase the charge mobility of the organic semiconductor film. As a method for improving the charge mobility of the organic semiconductor film, organic semiconductor molecules forming the organic semiconductor film have been highly oriented. As a method of forming an organic semiconductor film having such a high orientation, the surface of the substrate or the gate insulating film on which the organic semiconductor film is deposited is surface-treated, in particular, the surface of the gate insulating film on which the organic semiconductor film is deposited is self-organized It is known to coat with a monomolecular film (SAM: Self-Assembled Monolayer) (Patent Documents 1 and 2, and Non-Patent Documents 1 to 3).

  Here, as the substrate or gate insulating film on which the organic semiconductor film is deposited, a silicon oxide thin film can be used, and as the SAM covering the substrate or gate insulating film, an organosilane monomolecular film such as an alkylsilane single film is used. A molecular film can be used.

  Thus, when an organic semiconductor film is formed on a substrate or a gate insulating film that has been surface-modified by SAM in advance, the charge mobility of the organic semiconductor film is improved, and thereby the charge mobility that exceeds the current TFT made of amorphous silicon. An organic TFT having the above has been reported.

  Various techniques for modifying the surface of a substrate having an OH group such as silica by SAM such as organosilane (silane coupling agent) are known (Non-Patent Document 4). A solution method in which a silane coupling reaction between an OH group and an organosilane is promoted, and a gas phase method in which a reaction is performed in a gas phase using organosilane vapor are known as typical forming methods. As for the solution method, it is known that a SAM with high flatness can be obtained by performing a silane coupling reaction in a solution having a low water content (Non-Patent Document 5).

  In addition, a method of forming an organosilane thin film using a microcontact printing method is also known (Non-Patent Document 6). In this case, it is possible to form an organosilane thin film by patterning by applying organosilane to a stamp having a pattern and transferring the coupling agent to a substrate.

JP 2005-79560 A JP 2009-59751 A

H. Sirringhaus et al., Nature, 40, pp 4509-4521, 1999 A. Salleo et al., Applied Physics Letters, Vol. 81, No. 23, pp 4383-4385, 2002. Y. Y. Lin et al., IEEE Trans Electron Devices, 44, pp 1325-1331, 1997 S. Onclin et al., Angelwandte Chemie International Edition, 44, p6282-6304, 2005 Y. Wang et al., Langmuir, 19, 1159-1167, 2003 N. L. Jeon et al., Langmuir, 13, p3382-3391, 1997

  As described above, by forming the organic semiconductor film on the self-assembled monolayer (SAM), the organic semiconductor molecules constituting the organic semiconductor film are highly oriented, thereby improving the charge mobility of the organic semiconductor film In addition, the switching speed and the on / off ratio of the current have been improved. However, in spite of such improvements, there is a demand for further improving the characteristics of the organic semiconductor film.

  The objective of this invention is providing the alkylsilane laminated body which makes it possible to obtain the organic-semiconductor film which has the outstanding semiconductor characteristic. Such a laminate can be usefully used for an organic thin film transistor. Moreover, the objective of this invention is providing the method of manufacturing such an alkylsilane laminated body easily.

  The inventor of the present invention has found that the SAM of alkylsilane obtained by the contact printing method under a controlled atmosphere can solve the above problems, and has arrived at the present invention described below.

<1> An alkylsilane laminate having a base layer having a hydroxyl group on the surface, and an alkylsilane thin film formed on the base layer, wherein the critical surface energy Ec of the alkylsilane thin film and the carbon number of the alkylsilane An alkylsilane laminate in which x satisfies the following formula (1):
Ec ≦ 29.00−0.63x (mN / m) (1)
<2> The laminate according to <1>, wherein the alkylsilane thin film has an average thickness of 10 nm or less.
<3> The laminate according to <1> or <2>, wherein the roughness Ra of the alkylsilane thin film is 1 nm or less.
<4> The laminate according to any one of <1> to <3>, wherein the alkylsilane thin film contains a siloxane oligomer.
<5> The laminate according to any one of <1> to <4>, wherein the alkylsilane is a linear alkylsilane.
<6> The laminate according to any one of <1> to <5>, wherein the alkylsilane thin film is made of trichloroalkylsilane or trialkoxyalkylsilane as a raw material.
<7> The laminate according to any one of <1> to <6>, wherein the surface of the base layer having a hydroxyl group is provided by silica.
<8> The laminate according to any one of <1> to <7>, wherein the surface of the base layer having a hydroxyl group is provided by a silica layer laminated on a polymer substrate.
<9> The laminate according to any one of <1> to <8>, wherein the alkylsilane has 10 or more carbon atoms.
<10> A laminate according to any one of <1> to <9>, including forming the alkylsilane thin film on the underlayer by a contact printing method in an atmosphere of 5% or less humidity. Method.
<11> A source electrode, a drain electrode, a gate electrode, a gate insulating film, and an organic semiconductor film are provided on one surface of the substrate, and the source electrode, the drain electrode, and the gate electrode are insulated by the gate insulating film. And a thin film transistor that controls a current flowing through the organic semiconductor from the source electrode to the drain electrode by a voltage applied to the gate electrode,
The thin film transistor further includes an alkylsilane thin film, the substrate or gate insulating film has a hydroxyl group on the surface, and the alkylsilane thin film is formed on the substrate or gate insulating film having a hydroxyl group on the surface. And the critical surface energy Ec of the alkylsilane thin film and the carbon number x of the alkylsilane satisfy the following formula (1):
Ec ≦ 29.00−0.63x (mN / m) (1)

  According to the alkylsilane laminate of the present invention, when an organic semiconductor film is formed thereon, the organic semiconductor film can have excellent semiconductor characteristics such as rising characteristics. Moreover, according to the method of the present invention for producing an alkylsilane laminate, the alkylsilane laminate of the present invention can be obtained, and in particular, the alkylsilane laminate of the present invention can be obtained in a short time.

FIG. 1 is a diagram showing a first example of a thin film transistor of the present invention. FIG. 2 is a diagram showing a second example of the thin film transistor of the present invention. FIG. 3 is a diagram showing a third example of the thin film transistor of the present invention. FIG. 4 is a diagram showing a fourth example of the thin film transistor of the present invention. FIG. 5 is a diagram showing a fifth example of the thin film transistor of the present invention. FIG. 6 is a graph showing the relationship between the critical surface energy (Ec) of the alkylsilane thin films of Examples and Comparative Examples and the carbon number (x) of the alkyl chain.

  Below, the alkylsilane laminated body of this invention which has a base layer and the alkylsilane thin film formed on this base layer is demonstrated in detail regarding a thin-film transistor. However, the use of the alkylsilane laminate of the present invention is not limited to the following embodiments.

<< Thin Film Transistor >>
The thin film transistor of the present invention has a source electrode, a drain electrode, a gate electrode, a gate insulating film and an organic semiconductor film on one surface of the substrate, and the gate insulating film insulates the source electrode, the drain electrode and the gate electrode, The current flowing through the organic semiconductor film from the source electrode to the drain electrode is controlled by the voltage applied to the gate electrode.

  The thin film transistor of the present invention has an arbitrary structure capable of controlling the current flowing through the organic semiconductor from the source electrode to the drain electrode by the voltage applied to the gate electrode. Therefore, for example, the thin film transistor of the present invention can have the structure shown in FIGS.

  Here, in the embodiment shown in FIG. 1, an alkylsilane thin film (AS) is formed on a substrate (Sub) as an underlayer (Under), on which a source electrode (S), a gate electrode (G), and An organic semiconductor film (Semi) is formed, a gate insulating film (Ins) is formed on the organic semiconductor film (Semi), and a gate electrode (G) is further formed on the gate insulating film (Ins). ing. As shown in FIG. 5, the substrate (Sub) can also serve as the gate electrode (G).

  In the thin film transistor of the present invention, the substrate or gate insulating film has a hydroxyl group on the surface, the thin film transistor further has an alkylsilane thin film, and the alkylsilane thin film is formed directly on the substrate or gate insulating film having a hydroxyl group on the surface. The organic semiconductor film is directly formed on the alkylsilane thin film. That is, in the thin film transistor of the present invention, the base layer (Under) is used as a substrate (Sub) or gate insulating film (Ins) of the thin film transistor, and the alkylsilane thin film (AS) formed on the base layer (Under). An organic semiconductor film (Semi) is formed directly on the surface.

  Patent Documents 1 and 2 can be referred to for the general configuration of the thin film transistor of the present invention, but each part of the thin film transistor of the present invention will be described in more detail below.

<Thin film transistor substrate>
The substrate of the thin film transistor of the present invention can be made of any material capable of forming a thin film transistor by laminating a source electrode, a drain electrode, a gate electrode, a gate insulating film, an organic semiconductor film, and an alkylsilane thin film on one surface thereof. it can. Accordingly, examples of the substrate include a silica substrate, a glass substrate, a quartz substrate, an alumina substrate, a titania substrate, an inorganic material substrate such as a silicon substrate, a metal substrate, a resin substrate, and the like. In addition, when this board | substrate is made from an electroconductive material, a board | substrate can also serve as a gate electrode.

  In the thin film transistor of the present invention, the substrate or gate insulating film has a hydroxyl group on the surface, and this substrate or gate insulating film having a hydroxyl group on the surface is used as an underlayer for the alkylsilane thin film. Therefore, when the thin film transistor substrate is used as an underlayer for the alkylsilane thin film, the substrate needs to have a hydroxyl group on the surface when the alkylsilane thin film is laminated. In this case, examples of the substrate include a silica substrate, a glass substrate, a quartz substrate, an alumina substrate, a titania substrate, a silicon substrate with a thermal oxide film or a natural oxide film, and a resin substrate having a silica surface layer. Further, as the substrate in this case, a resin substrate coated with a resin layer having a hydroxyl group on the surface, a resin substrate having a hydroxyl group on the surface in advance, or the like can be used.

  Note that the substrate of the thin film transistor can have any thickness depending on the application.

<Thin film transistor-insulating film>
The gate insulating film of the thin film transistor of the present invention can be manufactured using any material having sufficient insulation to insulate the source electrode and the drain electrode from the gate electrode. Therefore, the gate insulating film can be made of, for example, resin, metal oxide, particularly silica, glass, alumina, titania or the like.

  As described above, in the thin film transistor of the present invention, the substrate or gate insulating film has a hydroxyl group on the surface, and this substrate or gate insulating film having a hydroxyl group on the surface is used as an underlayer for the alkylsilane thin film. Yes. Therefore, when the gate insulating film is used as an underlayer for the alkylsilane thin film, the gate insulating film needs to have a hydroxyl group on the surface when the alkylsilane thin film is stacked. In this case, a metal oxide, particularly a film of silica, glass, alumina, titania, or the like can be used as the gate insulating film.

  Note that the thickness of the gate insulating film can be any thickness necessary to obtain a thin film transistor.

<Thin film transistor-alkylsilane thin film>
The thin film transistor of the present invention has an alkylsilane thin film formed on a substrate or a gate insulating film as a base layer having a hydroxyl group on the surface. Here, the alkylsilane thin film is bonded to the hydroxyl group of the underlayer through a silane coupling reaction.

In the thin film transistor of the present invention, the critical surface energy of the alkylsilane thin film, that is, the critical surface energy of the surface of the alkylsilane thin film on the side opposite to the underlayer is expressed by the following formula (1), particularly formula (2), more particularly (3): Even more particularly satisfies (4):
Ec ≦ 29.00−0.63x (mN / m) (1)
Ec ≦ 28.00-0.63x (mN / m) (2)
Ec ≦ 27.00−0.63x (mN / m) (3)
Ec ≦ 26.00-0.63x (mN / m) (4)
(Here, Ec is the critical surface energy obtained by extrapolation by the Zisman plot, and x is the number of carbons contained in the alkylsilane)

On the other hand, the critical surface energy of the alkylsilane film that has been reported in the past generally satisfies the relational expression (A):
Ec = 30.50-0.63x (A)
(Here, Ec is the critical surface energy obtained by extrapolation by the Zisman plot, and x is the number of carbons contained in the alkylsilane)

  In the present invention, the value of the critical interface energy is a value obtained by measuring the contact angle using several kinds of wetting index standard solutions (JIS K 6768) and using a Zisman plot.

That is, the alkylsilane thin film of the thin film transistor of the present invention has a small critical surface energy compared to a conventional alkylsilane thin film having the same carbon number contained in the alkylsilane. The critical surface energy of the alkylsilane thin film depends on the functional group of the outermost layer and its density. Therefore, the alkylsilane thin film of the thin film transistor of the present invention has a higher film density than the conventional alkylsilane thin film having the same number of carbon atoms contained in the alkylsilane, thereby increasing the density of CH ₃ groups present on the surface. It is considered high.

  The average thickness of the alkylsilane thin film can be 10 nm or less, 7 nm or less, 5 nm or less, or 3 nm or less, and can be a thickness that ensures that the alkylsilane thin film is a monomolecular layer.

  Here, regarding the present invention, the average thickness of the thin film is an optically measured thin film thickness, and in particular, an ellipsometer that irradiates the sample with light and measures the change in the polarization state of the light reflected from the sample is used. Measured.

  The roughness Ra of the alkylsilane thin film can be 1.0 nm or less and 0.7 nm or less. This is because if the roughness is too large, the semiconductor characteristics of the organic semiconductor film formed on the alkylsilane thin film may deteriorate.

  Here, regarding the present invention, the average arithmetic roughness (centerline average roughness) (Ra) is defined in accordance with JIS B0601-1994. Specifically, the arithmetic average roughness (Ra) is determined by extracting a portion of the reference length l from the roughness curve in the direction of the center line, the center line of the extracted portion being the X axis, and the direction of the vertical magnification being the Y axis. And when the roughness curve is represented by y = f (x), it is represented by the following formula:

  It is preferable that the alkylsilane thin film has no protrusion having a height of 30 nm or more, 10 nm or more, 5 nm or more, or 3 nm or more. This is because when the alkylsilane thin film has protrusions that are too large, the semiconductor characteristics of the organic semiconductor film formed on the alkylsilane thin film may deteriorate.

  The alkylsilane for obtaining the alkylsilane thin film of the present invention is not particularly limited, and examples thereof include linear alkylsilanes and branched alkylsilanes, particularly linear alkylsilanes. The carbon number of the alkylsilane is 4 or more, 8 or more, or 10 or more, and may be 30 or less, 25 or less, and particularly 12 to 22. When the alkylsilane has too few carbon atoms, the characteristics of the organic semiconductor film may be insufficient. Specific examples of the alkylsilane include trihalogenalkylsilanes such as trichloroalkylsilane and trialkoxyalkylsilanes.

  The alkylsilane thin film of the present invention can be formed on a substrate or a gate insulating film as a base layer having a hydroxyl group on the surface by a contact printing method in an atmosphere having a humidity of 5% or less, preferably 3% or less. If the humidity in the atmosphere in which the contact printing method is performed is too high, the alkylsilane thin film of the present invention may not be obtained, and the formation of surface protrusions on the alkylsilane thin film may occur.

  The material for the stamp used in this contact printing method is not particularly limited, and examples thereof include silicone polymers such as polydimethylsiloxane. Further, the atmosphere in which the contact printing method is performed can be an inert atmosphere, particularly a nitrogen atmosphere.

  In the contact printing method for obtaining an alkylsilane thin film of the present invention, a raw material compound is supplied from a stamp by bringing a stamp coated with trichloroalkylsilane or trialkoxyalkylsilane itself or a solution containing them into contact with an underlayer. Then, an alkylsilane thin film is formed on the underlayer. In this case, the contact time for keeping the stamp and the underlayer in contact varies depending on the conditions, but is generally preferably 5 minutes or longer.

  When the alkylsilane thin film of the present invention is obtained by contact printing, the alkylsilane thin film of the present invention can be formed in a short time.

<Thin film transistor-organic semiconductor film>
The organic semiconductor film of the thin film transistor of the present invention means a semiconductor film composed of an aggregate of organic semiconductor molecules. For example, Patent Documents 1 and 2 such as regioregular polyalkylthiophene (P3AT) and Non-Patent Documents 1-6. An organic semiconductor film as shown in FIG.

  Therefore, examples of organic semiconductor molecules that can be used in the thin film transistor of the present invention include low molecular weight organic semiconductor molecules such as pentacene and acene-based compounds including thiophene oligomers (condensed polycyclic compounds condensed linearly), regio And high molecular organic semiconductor molecules such as regular polyalkylthiophene (P3AT) and poly (fluorenebithiophene) (F8T2).

  The organic semiconductor film of the thin film transistor of the present invention can have any thickness that can form a thin film transistor, and can have a thickness of, for example, 0.5 nm to 1 μm, or 2 nm to 250 nm. The organic semiconductor film can be obtained by an arbitrary method such as a molecular beam deposition method (MBE method), a vacuum deposition method, a chemical vapor deposition method, or a solution method. Among these, the solution method, that is, the dipping method, the spin coating method, and the like may be preferable in terms of productivity.

<Thin film transistor electrode>
The source electrode, the drain electrode, and the gate electrode of the thin film transistor of the present invention can be manufactured using any material having sufficient conductivity to be used as an electrode. Therefore, the electrode can be made of a metal such as gold, silver, copper, nickel, chromium, and aluminum, a conductive resin, a conductive metal oxide, or the like. The thickness of the electrode can be determined based on required conductivity, flexibility, and the like.

<Thin film transistor-other layers>
The thin film transistor of the present invention can have, for example, a protective layer, particularly a protective film formed on the organic semiconductor film, even if it has any other layer other than the above structure. Such a protective layer can be formed of, for example, polyparaxylylene.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example and a comparative example, this invention is not limited to this. In addition, the material and evaluation method which were used by the Example and the comparative example are as follows.

Silicon substrate:
An n-type silicon wafer with a 300 nm thermal oxide film (plane orientation <100>, specific resistance 1 to 10Ω) was treated with hot concentrated sulfuric acid for 30 minutes, and then several times using pure water, acetone, toluene, and hexane. Ultrasonic cleaning was performed twice. Furthermore, what was cleaned for 30 minutes with a UV ozone cleaning apparatus was used as a substrate.

Stamp material:
A Sylgard 184 made by Toray Dow Corning was cured into a flat plate shape to obtain a stamp material made of polydimethylsiloxane, which was used.

Organic thin film thickness:
Measurement was performed at an incident angle of 70 degrees using a M-150 ellipsometer manufactured by JASCO Corporation. The refractive index of the organic thin film was calculated as n = 1.45.

Contact angle:
Using a contact angle meter CA-X manufactured by Kyowa Interface Science, measurement was performed with pure water.

Critical surface energy:
The contact angle was measured using a wetting index standard solution (JIS K6768) having a critical surface energy of 30 mN / m, 35 mN / m, 40 mN / m, and 50 mN / m, and obtained by a zisman plot.

Surface roughness and protrusions:
The surface roughness and protrusions were measured in a 20 μm square visual field using a SPA400-DMF apparatus (atomic force microscope: AFM) manufactured by SII Nanotechnology.

Charge mobility and threshold voltage (Vth):
The charge mobility and threshold voltage (Vth) of the organic semiconductor film were evaluated using a 4200-SCS type semiconductor evaluation apparatus manufactured by Keithley.

<Example 1>
(Preparation of alkylsilane thin film (contact printing method in nitrogen with a humidity of 3% or less))
A 20 mM hexane solution of octadecyltrichlorosilane (linear, 18 carbon atoms) was prepared. The stamp material was immersed in the obtained octadecyltrichlorosilane solution and dried in nitrogen for 10 minutes.

  The dried stamp was brought into contact with the silicon substrate and held for 120 minutes. After removing the stamp, the substrate was washed with hexane and ethanol, and ultrasonically washed in ethanol for 3 minutes. All the steps so far were performed in a nitrogen atmosphere in a glove box whose humidity was controlled to 3% or less.

  Thereafter, the substrate was washed with pure water and heat-treated at 100 ° C. for 5 minutes to produce a substrate having an octadecylsilane thin film (that is, an alkylsilane thin film).

(Preparation of organic semiconductor film)
A solution for spin coating by dissolving 1 part by mass of regioregular poly (3-hexylthiophene) ("P3HT") (sold by Aldrich, manufactured by Prectronics, MW = 25000-35000, electronics grade) in 99 parts by mass of toluene Got. Using this spin coating solution, a P3HT film (that is, an organic semiconductor film) was spin coated (1800 rpm, 20 seconds) on the substrate having the alkylsilane thin film.

(Production of thin film transistor)
Gold was vacuum-deposited on the obtained organic semiconductor film by a mask vapor deposition method to form a source electrode and a drain electrode (L / w = 50 μm / 1.5 mm), and a thin film transistor was obtained using a silicon substrate as a gate electrode. . That is, a thin film transistor having a structure as shown in FIG. 5 was obtained.

(Evaluation)
The evaluation result about the obtained alkylsilane thin film and thin-film transistor is shown in Table 1 and FIG. Here, FIG. 6 shows the relationship between the critical surface energy (Ec) of the alkylsilane thin film and the carbon number (x) of the alkyl chain. Further, in FIG. 6, a straight line of Ec = 29.00−0.63x (formula (1)) is also shown for reference.

<Example 2>
This example is the same as Example 1 except that dodecyltrichlorosilane (linear, 12 carbon atoms) was used instead of octadecyltrichlorosilane (linear, 18 carbon atoms) as a raw material for the alkylsilane thin film. went. The evaluation result about the obtained alkylsilane thin film and thin-film transistor is shown in Table 1 and FIG.

<Example 3>
This example is the same as Example 1 except that octyltrichlorosilane (linear, 8 carbon atoms) was used instead of octadecyltrichlorosilane (linear, 18 carbon atoms) as the material for the alkylsilane thin film. went. The evaluation result about the obtained alkylsilane thin film and thin-film transistor is shown in Table 1 and FIG.

<Example 4>
This example is similar to Example 1 except that butyltrichlorosilane (linear, 4 carbon atoms) is used in place of octadecyltrichlorosilane (linear, 18 carbon atoms) as the material for the alkylsilane thin film. went. The evaluation result about the obtained alkylsilane thin film and thin-film transistor is shown in Table 1 and FIG.

<Comparative example 1>
(Preparation of alkylsilane thin film (contact printing method in air))
In the same manner as in Example 1, a stamp immersed in a solution of octadecyltrichlorosilane (linear, 18 carbon atoms) was dried in nitrogen for 10 minutes.

  The dried stamp was brought into contact with the silicon substrate and held for 1 minute. After removing the stamp, the substrate was washed with hexane and ethanol, and ultrasonically washed in ethanol for 30 minutes. Here, the step of bringing the stamp into contact with the silicon substrate and the subsequent cleaning step were performed in the atmosphere (humidity of about 60%).

  Thereafter, the substrate was washed with pure water and heat-treated at 100 ° C. for 5 minutes to produce a substrate having an octadecylsilane thin film (that is, an alkylsilane thin film). A thin film transistor was produced in the same manner as in Example 1 using this alkylsilane thin film.

  The evaluation result about the obtained alkylsilane thin film and thin-film transistor is shown in Table 1 and FIG.

<Comparative example 2>
(Preparation of alkylsilane thin film (liquid phase method))
A 20 mM toluene solution of octadecyltrichlorosilane (linear, 18 carbon atoms) was prepared. The silicon substrate was immersed in the obtained octadecyltrichlorosilane solution and held for 7 days. After immersion, the substrate was washed with toluene and ethanol, and ultrasonically washed in ethanol for 30 minutes. All the steps so far were performed in a glove box in which the humidity was controlled to 3% or less.

  Thereafter, the substrate was washed with pure water and heat-treated at 100 ° C. for 5 minutes to produce an alkylsilane thin film. A thin film transistor was produced in the same manner as in Example 1 by using the obtained alkylsilane thin film.

  The evaluation results for the obtained thin film transistor are shown in Table 1 and FIG.

<Comparative Example 3>
This comparative example was prepared in the same manner as in Comparative Example 2 except that dodecyltrichlorosilane (12 carbon atoms) was used instead of octadecyltrichlorosilane (linear, 18 carbon atoms) as a raw material for the alkylsilane thin film. A silane film was obtained. A thin film transistor was produced in the same manner as in Example 1 by using the obtained alkylsilane thin film.

  The evaluation results for the obtained thin film transistor are shown in Table 1 and FIG.

<Comparative example 4>
This comparative example is similar to Comparative Example 2 except that octyltrichlorosilane (8 carbon atoms) is used instead of octadecyltrichlorosilane (linear, 18 carbon atoms) as the material for the alkylsilane thin film. A membrane was obtained. A thin film transistor was produced in the same manner as in Example 1 by using the obtained alkylsilane thin film.

  The evaluation results for the obtained thin film transistor are shown in Table 1 and FIG.

<Comparative Example 5>
This comparative example is an alkylsilane film as in Comparative Example 2, except that butyltrichlorosilane (4 carbon atoms) is used instead of octadecyltrichlorosilane (linear, 18 carbon atoms) as the material of the alkylsilane thin film. Got. A thin film transistor was produced in the same manner as in Example 1 by using the obtained alkylsilane thin film.

  The evaluation results for the obtained thin film transistor are shown in Table 1 and FIG.

  From Table 1, it is understood that the organic semiconductor film of the example has excellent mobility and threshold voltage.

Claims (10)

An alkylsilane laminate having a base layer having a hydroxyl group on the surface, and an alkylsilane thin film formed on the base layer,
It said alkyl silane and carbon number x of critical surface energy Ec and alkylsilane thin film meets the equation (1) below:
Ec ≦ 29.00−0.63x (mN / m) (1)
The surface of the base layer having a hydroxyl group is provided by a silica layer laminated on a polymer substrate.
Alkyl silane laminate.   The laminated body of Claim 1 whose average thickness of the said alkylsilane thin film is 10 nm or less.   The laminated body of Claim 1 or 2 whose roughness Ra of the said alkylsilane thin film is 1 nm or less. The laminated body as described in any one of Claims 1-3 in which the said alkylsilane thin film contains a siloxane oligomer. The laminate according to any one of claims 1 to 4, wherein the alkylsilane is a linear alkylsilane. The laminate according to any one of claims 1 to 5, wherein the alkylsilane thin film is made of trichloroalkylsilane or trialkoxyalkylsilane as a raw material. The laminated body as described in any one of Claims 1-6 by which the surface which has the hydroxyl group of the said foundation | substrate layer is provided with the silica. The laminate according to any one of claims 1 to 7 , wherein the alkylsilane has 10 or more carbon atoms. The method for producing a laminate according to any one of claims 1 to 9, comprising forming the alkylsilane thin film on the underlayer by a contact printing method in an atmosphere having a humidity of 5% or less. A source electrode, a drain electrode, a gate electrode, a gate insulating film, and an organic semiconductor film on one surface of the substrate; the source electrode, the drain electrode, and the gate electrode are insulated by the gate insulating film; and A thin film transistor that controls a current flowing through the organic semiconductor from the source electrode to the drain electrode by a voltage applied to a gate electrode;
The thin film transistor further includes an alkylsilane thin film, the substrate or gate insulating film has a hydroxyl group on the surface, and the alkylsilane thin film is formed on the substrate or gate insulating film having a hydroxyl group on the surface. and wherein the critical surface energy Ec and the number of carbon atoms x alkylsilane alkylsilane thin film meets the equation (1) below:
Ec ≦ 29.00−0.63x (mN / m) (1)
The surface of the base layer having a hydroxyl group is provided by a silica layer laminated on a polymer substrate.
Thin film transistor.

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