JP2005149734A - Composition for forming transparent conductive film, manufacturing method of transparent conduction film, transparent conductive film, and electronic device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for a transparent conductive film by which, a transparent conductive film suitable for securing conductivity between the transparent conductive film and a semiconductor layer can be formed, a manufacturing method of the transparent conductive film using the composition for the transparent conductive film, the transparent conductive film formed by using the composition for the transparent conductive film, and an electronic device and an electronic apparatus with high reliability. <P>SOLUTION: The composition for a transparent conductive film used for forming the transparent conductive film contains a material for the transparent conductive film composed of fine particles of conductive metal oxide and/or a precursor thereof, hydrogen fluoride or an HF generating material capable of generating hydrogen fluoride, and fluid medium 1 dissolving or dispersing at least a part of the material for the transparent conductive film. A volume of hydrogen fluoride or hydrogen fluoride generated from the HF generating material is 1×10<SP>-4</SP>to 5×10<SP>-1</SP>wt.part against 1 wt. part of the fluid medium 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a composition for forming a transparent conductive film, a method for forming a transparent conductive film, a transparent conductive film, an electronic device, and an electronic apparatus.

In recent years, in electronic devices, wiring has been multilayered in order to achieve high integration.
Transparent conductive films have excellent electrical conductivity and transparency, and are widely used for those requiring electrical conductivity and transparency. For example, in a liquid crystal image display device, a transparent conductive film is provided as a pixel electrode and a scanning electrode for driving liquid crystal.
In an electronic device having multilayer wiring, when electrically connecting the upper and lower wiring patterns arranged via the interlayer insulating film, such a transparent conductive film is connected to the lower conductive part made of silicon. The electrode may be formed.

By the way, silicon is very easily oxidized and usually has a film (natural oxide film) formed by being naturally oxidized on the surface thereof. This natural oxide film is an insulating material, and when the transparent conductive film is connected to the lower conductive portion where the natural oxide film is formed as it is, the conductivity between the silicon and the transparent conductive film is inhibited by the natural oxide film on the silicon surface, There was a problem that the contact resistance value was increased. As a result, there has been a problem that the drive voltage of the entire apparatus becomes high.
As a method for removing such a natural oxide film, various methods have been conventionally known (see, for example, Patent Document 1).

  However, when the natural oxide film is removed by sputter etching as in the method of removing the natural oxide film described in Patent Document 1, not only the natural oxide film is removed but also the surface of the lower conductive portion and the interlayer insulating film. This causes damage to the surface of other parts, etc., resulting in variations in electrical characteristics from pixel to pixel, and lowering the adhesion with the upper film, resulting in a decrease in the reliability of the finally obtained device. Arise. In addition, since the apparatus for performing sputter etching uses a high vacuum apparatus, it is difficult to manage conditions and the like, and it is very expensive and wastes energy. Although a method of removing the natural oxide film by a method such as wet etching is also conceivable, there is a problem that the process becomes complicated.

JP-A-5-267207

  An object of the present invention is to provide a transparent conductive film forming composition capable of suitably forming a transparent conductive film so as to ensure conductivity between the transparent conductive film and the semiconductor layer, and the transparent conductive film forming composition. It is in providing the formation method of the used transparent conductive film, the transparent conductive film formed using the composition for transparent conductive film formation, a highly reliable electronic device, and an electronic device.

Such an object is achieved by the present invention described below.
The composition for forming a transparent conductive film of the present invention is a composition for forming a transparent conductive film used for forming a transparent conductive film,
A transparent conductive film material composed of conductive metal oxide fine particles and / or precursors thereof; and
Hydrogen fluoride or an HF generating material capable of generating hydrogen fluoride;
And a liquid medium in which at least a part of the transparent conductive film material is dissolved or dispersed.
Thereby, the composition for transparent conductive film formation which can form a transparent conductive film suitably can be provided so that the electroconductivity of a transparent conductive film and a semiconductor layer may be ensured.

In the composition for forming a transparent conductive film of the present invention, the amount of the hydrogen fluoride or the hydrogen fluoride generated from the HF generating material is 1 × 10 ^{−4 to} 5 × with respect to 1 part by weight of the liquid medium. 10 ^-1 parts by weight is preferred.
Thereby, the natural oxide film of silicon can be efficiently removed.
The composition for forming a transparent conductive film of the present invention preferably contains a densification promoting substance that shrinks by heating and promotes densification of the metal oxide fine particles.
Thereby, the densification promoting substance shrinks by the heat treatment, and the densification of the transparent conductive film can be promoted.

In the composition for forming a transparent conductive film of the present invention, it is preferable that the densification promoting substance has a weight reduction rate of 10% or more when heated from room temperature to 400 ° C.
Thereby, the densification of the transparent conductive film can be further promoted, and the formed transparent conductive film can be made more excellent in conductivity.
In the composition for forming a transparent conductive film of the present invention, it is preferable that the densification accelerating substance is such that its contraction has conductivity.
Thereby, the electroconductivity of the formed transparent conductive film can be improved more.

In the composition for forming a transparent conductive film of the present invention, the transparent conductive film material contains metal oxide fine particles,
It is preferable that the densification promoting substance is mixed in the formed transparent conductive film so that the shrinkage is 0.01 to 1 part by weight with respect to 1 part by weight of the metal oxide fine particles.
Thereby, densification of metal oxide fine particles can be sufficiently advanced.

In the composition for forming a transparent conductive film of the present invention, it is preferable that the densification promoting substance is the precursor, and at least a part of the precursor is changed to a metal oxide by the heating.
Thus, in the obtained transparent conductive film, the strength and adhesion of the film can be improved and the film characteristics can be stabilized.
In the composition for forming a transparent conductive film of the present invention, the transparent conductive film material contains metal oxide fine particles,
It is preferable that the metal oxide obtained by heating the densification promoting substance and the metal oxide fine particles as the main material of the transparent conductive film material are of the same type.
Thereby, the formed transparent conductive film is more excellent in conductivity, film strength and adhesion, and stability of film characteristics.

In the composition for forming a transparent conductive film of the present invention, the metal oxide fine particles preferably have an average particle size of 2 to 2000 nm.
Thereby, while handling of the composition for transparent conductive film formation becomes easy, the formed transparent conductive film can be made more excellent in conductivity, film strength and adhesion, and stability in film characteristics. .

In the composition for forming a transparent conductive film of the present invention, the metal oxide fine particles are preferably mixed so as to be 0.05 to 0.9 parts by weight with respect to 1 part by weight of the liquid medium.
As a result, it becomes possible to form transparent conductive films having various thicknesses, and to make the formed transparent conductive films more excellent in conductivity, film strength and adhesion, and stability of film characteristics. it can.

The method for forming a transparent conductive film of the present invention is a method for forming a transparent conductive film on the surface of a member at least part of the vicinity of the surface made of silicon,
It has the provision process which provides the composition for transparent conductive film formation of this invention to the surface of the said member.
Thereby, a transparent conductive film can be easily and easily formed while removing a natural oxide film formed on the surface of silicon.

In the method for forming a transparent conductive film of the present invention, the member preferably has a film mainly composed of silicon, and at least the transparent conductive film forming composition is applied on the film.
Thereby, a transparent conductive film can be easily and easily formed while removing a natural oxide film formed on the surface of silicon.
In the method for forming a transparent conductive film of the present invention, it is preferable to have at least one heat treatment step after the application step.
As a result, the transparent conductive film can be formed easily and simply while removing the natural oxide film of silicon more efficiently.

In the method for forming a transparent conductive film of the present invention, it is preferable that the heat treatment step includes a first heat treatment step and a second heat treatment step in which the heat treatment is performed at a higher temperature than the heat treatment in the first heat treatment step. .
As a result, the transparent conductive film can be formed easily and simply while removing the natural oxide film of silicon more efficiently.

In the method for forming a transparent conductive film of the present invention, when the temperature of the heat treatment in the first heat treatment step is T ₁ and the temperature of the heat treatment in the second heat treatment step is T ₂ , a relationship of T ₂ > T ₁ +20 It is preferable to satisfy
By satisfying such a relationship, for example, the etching amount of the natural oxide film can be controlled, and hydrogen fluoride, a liquid medium, or the like can be more reliably removed without damaging other materials. it can.

In the method for forming a transparent conductive film of the present invention, the heat treatment temperature T1 in the _first heat treatment step is preferably 20 to 100 ° C.
Thereby, the natural oxide film on the joint surface with the lower conductive portion formed of silicon can be more efficiently removed.
In the method for forming a transparent conductive film of the present invention, the heat treatment temperature T2 in the _second heat treatment step is preferably 20 to 200 ° C.
Thereby, hydrogen fluoride, a liquid medium, etc. can be removed more reliably.

In the method for forming a transparent conductive film of the present invention, it is preferable that the heat treatment step further includes a third heat treatment step in which heat treatment is performed at a higher temperature than the heat treatment in the second heat treatment step.
Thereby, densification of metal oxide fine particles can be sufficiently advanced.
In the method for forming a transparent conductive film of the present invention, when the temperature of the heat treatment in the second heat treatment step is T ₂ and the temperature of the heat treatment in the third heat treatment step is T ₃ , a relationship of T ₃ > T ₂ +50 It is preferable to satisfy
By satisfying such a relationship, it is possible to more reliably remove the remaining hydrogen fluoride, liquid medium, and the like, and to sufficiently fix the metal oxide fine particles and shrink the precursor.

In the method for forming a transparent conductive film of the present invention, the heat treatment temperature T3 in the _third heat treatment step is preferably 50 to 500C.
Thereby, while remaining hydrogen fluoride, a liquid medium, etc. are removed more reliably, fixation of metal oxide fine particles and shrinkage | contraction of a precursor can fully be advanced.
In the method for forming a transparent conductive film of the present invention, the time in the first heat treatment step is preferably 10 seconds to 600 seconds.
Thereby, the natural oxide film on silicon can be removed more reliably.

In the method for forming a transparent conductive film of the present invention, the time in the second heat treatment step is preferably 1 to 40 minutes.
Thereby, hydrogen fluoride, a liquid medium, etc. can be removed more reliably.
In the method for forming a transparent conductive film of the present invention, the time for the third heat treatment step is preferably 1 to 180 minutes.
Thereby, the densification of the transparent conductive film can be sufficiently advanced.

The transparent conductive film of the present invention is formed by the method for forming a transparent conductive film of the present invention.
As a result, a transparent conductive film having high density and high conductivity is obtained, and the film strength and adhesion, and the stability of the film characteristics are excellent.
The transparent conductive film of the present invention is connected to a semiconductor layer,
The contact resistance value between the transparent conductive film and the semiconductor layer is preferably 100 kΩ or less.
Thereby, when an electronic device is constructed, the electronic device can have a faster response speed.

The electronic device of the present invention includes the transparent conductive film of the present invention.
Thereby, an electronic device with high reliability can be obtained.
An electronic apparatus according to the present invention includes the electronic device according to the present invention.
As a result, a highly reliable electronic device can be obtained.

Hereinafter, it demonstrates in detail based on suitable embodiment of the composition for transparent conductive film formation of this invention, the formation method of a transparent conductive film, a transparent conductive film, an electronic device, and an electronic device.
Hereinafter, a case where the electronic device of the present invention is applied to a liquid crystal panel will be described as an example.
<Configuration of LCD panel>
FIG. 1 is a schematic longitudinal sectional view showing a preferred embodiment of a liquid crystal panel to which the present invention is applied, and FIG. 2 is an enlarged sectional view in the vicinity of a thin film transistor of the liquid crystal panel shown in FIG.
As shown in FIG. 1, a liquid crystal panel (TFT liquid crystal panel) 100 includes a TFT substrate (liquid crystal driving substrate) 9, an alignment film 3 bonded to the TFT substrate 9, a counter substrate 12 for liquid crystal panels, and a liquid crystal panel use. The alignment film 3 ′ bonded to the counter substrate 12, the liquid crystal layer 2 made of liquid crystal sealed in the gap between the alignment film 3 and the alignment film 3 ′, and the outer surface side (alignment) of the TFT substrate (liquid crystal driving substrate) 9 Bonded to the polarizing film 4 bonded to the surface opposite to the surface facing the film 3 and the outer surface side of the counter substrate 12 for liquid crystal panel (the surface opposite to the surface facing the alignment film 3 ′) And a polarizing film 4 ′.

The liquid crystal layer 2 is mainly composed of liquid crystal molecules.
As the liquid crystal molecules constituting the liquid crystal layer 2, any liquid crystal molecules that can be aligned such as nematic liquid crystal and smectic liquid crystal may be used. However, in the case of a TN type liquid crystal panel, those that form nematic liquid crystal are preferable. For example, phenylcyclohexane derivative liquid crystal, biphenyl derivative liquid crystal, biphenylcyclohexane derivative liquid crystal, terphenyl derivative liquid crystal, phenyl ether derivative liquid crystal, phenyl ester derivative liquid crystal, bicyclohexane derivative liquid crystal, azomethine derivative liquid crystal, azoxy derivative liquid crystal, pyrimidine derivative liquid crystal, dioxane Examples include derivative liquid crystals and cubane derivative liquid crystals. Furthermore, liquid crystal molecules in which a fluorine-based substituent such as a monofluoro group, a difluoro group, a trifluoro group, a trifluoromethyl group, a trifluoromethoxy group, or a difluoromethoxy group is introduced into these nematic liquid crystal molecules are also included.

Alignment films 3 and 3 ′ are disposed on both surfaces of the liquid crystal layer 2. The alignment films 3 and 3 ′ have a function of regulating the alignment state (when no voltage is applied) of the liquid crystal molecules constituting the liquid crystal layer 2.
The alignment films 3 and 3 ′ are usually mainly composed of a polymer material such as polyimide resin, polyamideimide resin, polyvinyl alcohol, polytetrafluoroethylene. Among the polymer materials, polyimide resin and polyamideimide resin are particularly preferable. When the alignment films 3 and 3 ′ are mainly composed of a polyimide resin or a polyamide-imide resin, a polymer film can be easily formed in the manufacturing process, and excellent properties such as heat resistance and chemical resistance can be obtained. It will have.

In addition, as the alignment films 3 and 3 ′, a treatment for imparting an alignment function for restricting the alignment of the liquid crystal molecules constituting the liquid crystal layer 2 is usually applied to the film formed of the material as described above. Things are used. Examples of the treatment method for imparting the alignment function include a rubbing method and a photo-alignment method.
The rubbing method is a method of rubbing (rubbing) the surface of the film in a certain direction using a roller or the like. By performing such treatment, the film has anisotropy in the rubbed direction, and the alignment direction of liquid crystal molecules constituting the liquid crystal layer can be regulated.

The photo-alignment method is a method of selectively reacting only molecules in a specific direction among polymers constituting the film by irradiating light such as linearly polarized ultraviolet light near the surface of the film. By performing such treatment, the film has anisotropy, and the alignment direction of the liquid crystal molecules constituting the liquid crystal layer can be regulated.
The alignment treatment as described above is usually performed on the surface of the electrode (transparent conductive film 14, pixel electrode 92) formed on the substrate (joint of the microlens substrate 11 and the black matrix 13, TFT substrate 9). After the film made of the material is formed, the film is applied to the film. Examples of the method for forming a film on the electrode include dipping, doctor blade, spin coating, brush coating, spray coating, electrostatic coating, electrodeposition coating, various coating methods such as electrodeposition coating, roll coater, thermal spraying, electrolytic plating, and immersion. Examples include wet plating methods such as plating and electroless plating, chemical vapor deposition methods (CVD) such as vacuum deposition, sputtering, thermal CVD, plasma CVD, and laser CVD, and dry plating methods such as ion plating. The spin coating method is preferred. By using the spin coating method, a uniform and uniform film can be formed easily and reliably.

Such an alignment film preferably has an average thickness of 20 to 120 nm, more preferably 30 to 80 nm.
If the average thickness of the alignment film is less than the lower limit, it may be difficult to impart a sufficient alignment function to the alignment film. On the other hand, when the average thickness of the alignment film exceeds the above upper limit value, the driving voltage becomes high and the power consumption may increase.

The counter substrate 12 for the liquid crystal panel is provided on the microlens substrate 11, the surface layer 114 of the microlens substrate 11, the black matrix 13 in which the opening 131 is formed, and the black matrix 13 on the surface layer 114. A transparent conductive film (common electrode) 14.
The microlens substrate 11 includes a microlens concave substrate (first substrate) 111 provided with a plurality of (many) concave portions (microlens concave portions) 112 having a concave curved surface, and the microlens concave substrate 111. And a surface layer (second substrate) 114 joined via a resin layer (adhesive layer) 115 on the surface provided with the recess 112, and the resin layer 115 fills the recess 112. The microlens 113 is formed by the resin thus formed.

The substrate with concave portions for microlenses 111 is manufactured from a flat base material (transparent substrate), and a plurality of (many) concave portions 112 are formed on the surface thereof. The recess 112 can be formed by, for example, a dry etching method, a wet etching method, or the like using a mask.
The substrate with concave portions for microlenses 111 is made of, for example, glass such as quartz glass, or a plastic material such as polyethylene terephthalate.

It is preferable that the thermal expansion coefficient of the base material is substantially equal to the thermal expansion coefficient of a glass substrate 91 described later (for example, the ratio of the thermal expansion coefficients of the two is about 1/10 to 10). As a result, in the obtained liquid crystal panel, warpage, deflection, peeling, and the like caused by differences in the thermal expansion coefficients of the two when the temperature changes are prevented.
From this viewpoint, it is preferable that the substrate 111 with concave portions for microlenses and the glass substrate 91 are made of the same kind of material. This effectively prevents warpage, deflection, peeling, and the like due to differences in the thermal expansion coefficient when the temperature changes.

  In particular, when the microlens substrate 11 is used for a high-temperature polysilicon TFT liquid crystal panel (HTPS), the substrate 111 with concave portions for microlenses is preferably made of quartz glass. The TFT liquid crystal panel has a TFT substrate as a liquid crystal driving substrate. For such a TFT substrate, quartz glass whose characteristics are unlikely to change depending on the manufacturing environment is preferably used. For this reason, the micro liquid crystal substrate 111 with concave portions for microlenses is made of quartz glass, so that a TFT liquid crystal panel with excellent stability that is less likely to be warped or bent can be obtained.

A resin layer (adhesive layer) 115 that covers the recess 112 is provided on the upper surface of the substrate with recesses 111 for microlenses.
The concave portion 112 is filled with the constituent material of the resin layer 115 to form the microlens 113.
The resin layer 115 can be made of, for example, a resin (adhesive) having a refractive index higher than the refractive index of the constituent material of the substrate 111 with concave portions for microlenses. For example, acrylic resin, epoxy resin, acrylic epoxy It can be suitably configured with an ultraviolet curable resin or the like.

A flat surface layer 114 is provided on the upper surface of the resin layer 115.
The surface layer (glass layer) 114 can be made of glass, for example. In this case, it is preferable that the thermal expansion coefficient of the surface layer 114 is substantially equal to the thermal expansion coefficient of the substrate 111 with concave portions for microlenses (for example, the ratio of the thermal expansion coefficients of the two is about 1/10 to 10). As a result, warpage, deflection, peeling, and the like caused by the difference in thermal expansion coefficient between the substrate 111 with concave portions for microlenses and the surface layer 114 are prevented. Such an effect can be more effectively obtained when the substrate with concave portions for microlenses 111 and the surface layer 114 are made of the same material.

When the microlens substrate 11 is used in a liquid crystal panel, the thickness of the surface layer 114 is usually about 5 to 1000 μm, more preferably about 10 to 150 μm, from the viewpoint of obtaining necessary optical characteristics.
In addition, the surface layer (barrier layer) 114 can also be comprised, for example with ceramics. Examples of ceramics include nitride ceramics such as AlN, SiN, TiN, and BN, oxide ceramics such as Al ₂ O ₃ and TiO ₂ , and carbide ceramics such as WC, TiC, ZrC, and TaC. Can be mentioned. When the surface layer 114 is made of ceramics, the thickness of the surface layer 114 is not particularly limited, but is preferably about 20 nm to 20 μm, and more preferably about 40 nm to 1 μm.
Such a surface layer 114 can be omitted if necessary.

The black matrix 13 has a light blocking function and is made of, for example, a metal such as Cr, Al, Al alloy, Ni, Zn, Ti, or a resin in which carbon, titanium, or the like is dispersed.
The transparent conductive film (electrode) 14 has conductivity, for example, indium tin oxide (ITO), indium oxide (IO), tin oxide (SnO ₂ ), antimontin oxide (ATO), indium zinc oxide (IZO). Etc.

The TFT substrate 9 is a substrate that drives the liquid crystal of the liquid crystal layer 2, and includes a glass substrate 91, a base insulating film 94 provided on the glass substrate 91, a base insulating film 94, and a matrix (matrix). A plurality of (many) pixel electrodes 92 and a plurality of (many) thin film transistors (TFTs) 93 corresponding to the pixel electrodes 92. In FIG. 1, the description of the sealing material, the wiring, etc. is omitted.
The glass substrate 91 is preferably made of quartz glass for the reasons described above.

The material of the base insulating film 94 is not particularly limited, for example, SiO _2, TEOS (ethyl silicate), can be used polysilazane, polyimide, a Low-K material or the like. The base insulating film 94 can be formed by applying a liquid insulating material such as SOG (Spin On Glass) having a siloxane bond to the glass substrate 91, firing it, and thermally decomposing it. Thereby, it is not necessary to use an expensive vacuum device or the like, and input energy and time required for film formation can be saved. The liquid insulating material can be applied, for example, by spin coating, dip coating, liquid mist chemical deposition (LSMCD), slit coating, or the like. Also, the liquid insulating material can be applied by a quantitative discharge device such as a printer head of a so-called inkjet printer. By using this quantitative discharge device, it is possible to apply only to a desired portion, so that the material can be saved.

The pixel electrode 92 drives the liquid crystal molecules of the liquid crystal layer 2 (changes the alignment of the liquid crystal) by charging and discharging with the transparent conductive film (common electrode) 14. The pixel electrode 92 is made of the same material as that of the transparent conductive film 14 described above, for example.
The thin film transistor 93 is connected to the corresponding pixel electrode 92 in the vicinity. The thin film transistor 93 is connected to a control circuit (not shown) and controls a current supplied to the pixel electrode 92. Thereby, charging / discharging of the pixel electrode 92 is controlled.

  As shown in FIG. 2, the thin film transistor 93 is provided over the base insulating film 94, a semiconductor layer 9314 including a channel region 9320, a source region 9316, and a drain region 9318, and a gate provided so as to cover the semiconductor layer 9314. An insulating film 9326, an insulating layer 9342, a gate electrode 9351 provided so as to face the channel region 9320 with the gate insulating film 9326 interposed therebetween, a conductive portion 9356 provided on the insulating layer 9342 above the gate electrode 9351, A conductive portion (a transparent conductive film of the present invention) 9352 provided on the insulating layer 9342 above the source region 9316 and functioning as a source electrode, and a conductive function provided on the insulating layer 9342 above the drain region 9318 and functioning as a drain electrode. Part (transparent conductive film of the present invention) 9354.

In this embodiment, a semiconductor layer 9314 is provided on the base insulating film 94. The semiconductor layer 9314 is made of silicon such as polycrystalline silicon or amorphous silicon.
As described above, the semiconductor layer 9314 includes the channel region 9320, the source region 9316, and the drain region 9318. As shown in FIG. 2, the semiconductor layer 9314 has a source region (lower conductive portion) 9316 formed on one side of the channel region 9320 and a drain region (lower conductive portion) 9318 on the other side of the channel region 9320. Is formed.

The channel region 9320 is made of, for example, an intrinsic semiconductor material. The source region 9316 and the drain region 9318 are made of a semiconductor material into which an n-type impurity such as phosphorus is introduced (doped), for example. Note that the structure of the semiconductor layer 9314 is not limited to this structure, and the source region 9316 and the drain region 9318 may be formed using a semiconductor material into which a p-type impurity is introduced, for example. The channel region 9320 may be made of a semiconductor material into which a p-type or n-type impurity is introduced, for example.
Such a semiconductor layer 9314 is covered with an insulating film (a gate insulating film 9326 and an insulating layer 9342). In such an insulating film, a portion interposed between the channel region 9320 and the conductive portion 9356 functions as a gate insulating layer serving as a path for an electric field generated between the channel region 9320 and the conductive portion 9356.

The constituent materials of the gate insulating film 9326 and the insulating layer 9342 are not particularly limited. For example, a silicon compound such as SiO ₂ , TEOS (ethyl silicate), or polysilazane can be used. Needless to say, the gate insulating film 9326 and the insulating layer 9342 may be formed of a material other than the above, for example, resin, ceramics, or the like.
A conductive portion 9352, a conductive portion 9354, and a conductive portion 9356 are provided over the insulating layer 9342. As described above, the conductive portion 9356 is formed above the channel region 9320. The conductive portion 9352 is in contact with the source region 9316. The conductive portion 9354 is in contact with the drain region 9318.

  As shown in FIG. 2, a hole (contact hole) communicating with the source region 9316 is formed in a region where the source region 9316 of the gate insulating film 9326 and the insulating layer 9342 is formed. The conductive portion 9352 is in contact with the source region 9316 through this hole. A hole communicating with the drain region 9318 is formed in a region where the drain region 9318 of the gate insulating film 9326 and the insulating layer 9342 is formed. The conductive portion 9354 is in contact with the drain region 9318 through this hole.

  In the liquid crystal panel 100 of the present embodiment, the conductive portion 9354 is in contact with the pixel electrode 92. That is, the conductive portion 9354 is electrically connected to the pixel electrode 92. The plurality of conductive portions 9352 constituting the liquid crystal panel 100 are electrically connected to each other at a portion not shown. Furthermore, the plurality of conductive portions 9356 constituting the liquid crystal panel 100 can be connected to other circuits in parallel.

The conductive portion 9352, the conductive portion 9354, and the conductive portion 9356 include, for example, indium tin oxide (ITO), indium oxide (IO), tin oxide (SnO ₂ ), antimontin oxide (ATO), and indium zinc oxide (IZO). , Al, Al alloy, Cr, Mo, Ta, or other conductive material. Note that a passivation film (not shown) made of a material such as SiO ₂ or SiN may be formed on these conductive portions.
Note that a method for forming the conductive portion 9352 and the conductive portion 9354 will be described in detail later.

As shown in FIG. 1, a polarizing film (polarizing plate, polarizing film) 4 is disposed on the outer surface side of the TFT substrate (liquid crystal driving substrate) 9 (the surface opposite to the surface facing the alignment film 3). ing. Similarly, a polarizing film (polarizing plate, polarizing film) 4 ′ is disposed on the outer surface side of the counter substrate for liquid crystal panel 12 (the surface side opposite to the surface facing the alignment film 3 ′).
Examples of the constituent material of the polarizing films 4 and 4 ′ include polyvinyl alcohol (PVA). Moreover, as a polarizing film, you may use what doped the said material with iodine.

As a polarizing film, what extended | stretched the film comprised with the said material to the uniaxial direction can be used, for example.
By disposing such polarizing films 4 and 4 ′, the light transmittance can be controlled more reliably by adjusting the amount of energization.
The direction of the polarization axis of the polarizing films 4 and 4 ′ is usually determined according to the alignment direction of the alignment films 3 and 3 ′.

In such a liquid crystal panel 100, normally, one micro lens 113, one opening 131 of the black matrix 13 corresponding to the optical axis Q of the micro lens 113, one pixel electrode 92, and such a pixel. One thin film transistor 93 connected to the electrode 92 corresponds to one pixel.
Incident light L incident from the liquid crystal panel counter substrate 12 side passes through the microlens concave substrate 111 and is condensed when passing through the microlens 113, while opening the resin layer 115, the surface layer 114, and the black matrix 13. 131, the transparent conductive film 14, the liquid crystal layer 2, the pixel electrode 92, and the glass substrate 91 are transmitted. At this time, since the polarizing film 4 ′ is provided on the incident side of the microlens substrate 11, the incident light L is linearly polarized when the incident light L passes through the liquid crystal layer 2. At this time, the polarization direction of the incident light L is controlled in accordance with the alignment state of the liquid crystal molecules in the liquid crystal layer 2. Therefore, the luminance of the emitted light can be controlled by transmitting the incident light L transmitted through the liquid crystal panel 100 to the polarizing film 4.

Thus, the liquid crystal panel 100 includes the microlens 113, and the incident light L that has passed through the microlens 113 is collected and passes through the openings 131 of the black matrix 13. On the other hand, the incident light L is shielded in a portion where the opening 131 of the black matrix 13 is not formed. Therefore, in the liquid crystal panel 100, unnecessary light is prevented from leaking from portions other than the pixels, and attenuation of the incident light L at the pixel portions is suppressed. For this reason, the liquid crystal panel 100 has high light transmittance in the pixel portion.
In the liquid crystal panel 100, for example, the alignment films 3 and 3 ′ are bonded to the TFT substrate 9 and the liquid crystal panel counter substrate 12, respectively, and then both are bonded via a sealing material (not shown). Next, the liquid crystal can be injected into the void portion from the enclosed hole (not shown) of the void portion formed thereby, and then the enclosed hole is closed.

<Composition for forming transparent conductive film>
Next, the composition for forming a transparent conductive film of the present invention will be described.
The composition for forming a transparent conductive film of the present invention is used, for example, for forming the conductive part 9352 and the transparent conductive film constituting the conductive part 9354, as described above. Or a transparent conductive film material composed of a precursor thereof, hydrogen fluoride, or an HF generating material capable of generating hydrogen fluoride, and a liquid medium in which at least a part of the transparent conductive film material is dissolved or dispersed. It is a waste.
When forming the transparent conductive film, the transparent conductive film-forming composition is supplied onto the substrate to form a film, and then the film is subjected to, for example, drying treatment, heat treatment, etc. A membrane can be obtained.

[Transparent conductive film material]
<1> Metal Oxide Fine Particles Any metal oxide fine particles constituting the transparent conductive film material can be used as long as they have conductivity, but they have a relatively high transparency (light transmittance). What has is preferable.

  Examples of such metal oxide fine particles include Li, Be, B, Na, Mg, Al, Si, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Nb, Mo, Cd, In, Sn, Sb, Cs, Ba, La, Hf, Ta, W, Tl, Pb, Bi, Ce, Pr, Nd, Pm, Sm, Eu, Gd, An oxide containing Tb, Dy, Ho, Er, Tm, Yb, Lu, or the like can be given.

Among these, as the metal oxide fine particles, indium oxide containing Sn (ITO), tin oxide containing Sb (ATO), tin oxide containing F (FTO), Al, Co, Fe, In, among others Zinc oxide containing at least one of Sn, Ti and Ti is preferred. These transparent conductive film materials have particularly high conductivity and transparency.
Moreover, the above metal oxide fine particles may be used individually by 1 type, and may be used in combination of 2 or more types.

In addition, when the particle | grains which use Sn indium oxide (ITO) as a main material as a metal oxide fine particle are used, the atomic ratio (indium / tin ratio) of indium and tin is 99 / 1-80 / It is preferably 20, and more preferably 97/3 to 85/15.
The shape of the metal oxide fine particles may be any shape such as a spherical shape, a needle shape, or a leaf shape, but is preferably a spherical shape. By using spherical metal oxide fine particles, a dense transparent conductive film can be easily formed.

  In this case, the average particle diameter of the metal oxide fine particles is preferably 2 to 2000 nm, more preferably 5 to 1000 nm, and still more preferably 10 to 500 nm. If the average particle size of the metal oxide fine particles is too small, the change in the film characteristics over time accompanying an increase in the surface area of the metal oxide fine particles may become remarkable. On the other hand, if the average particle size of the metal oxide fine particles is too large, the gap between the metal oxide fine particles is increased in the formed transparent conductive film, and as a result, the contact area between the metal oxide fine particles is reduced, Sufficient conductivity may not be obtained, and the strength, adhesion and film characteristics of the film may be reduced.

When metal oxide fine particles having other shapes are used, it is preferable that the average value of the maximum length of these metal oxide fine particles is in the range of the average particle diameter.
In addition, the metal oxide fine particles are preferably used in a single shape from the viewpoint of densifying (adhering) them more securely, but two or more different shapes may be used in combination. May be.

  Such metal oxide fine particles are preferably mixed so as to be 0.05 to 0.9 parts by weight with respect to 1 part by weight of the liquid medium in which the fine particles are dissolved or dispersed. It is more preferable to mix so that it becomes. If the mixing amount (addition amount) of the metal oxide fine particles is too small, the formed transparent conductive film may be too thin and may be easily disconnected, or sufficient conductivity as the conductive film may not be obtained. On the other hand, if the mixing amount of the metal oxide fine particles is too large, the transparent conductive film becomes thicker and the transmittance decreases, or the dispersibility of the metal oxide fine particles in the transparent conductive film forming composition decreases. There is a possibility that preparation of a composition for forming a transparent conductive film and application (supply) onto a substrate may be difficult.

<2> Metal Oxide Precursor The metal oxide precursor (hereinafter also simply referred to as a precursor) constituting the transparent conductive film material is a metal oxide obtained by subsequent heating (heat treatment) having conductivity. Any material can be used as long as it is present, but it is preferable that the metal oxide obtained by the heating has relatively high transparency (light transmittance).

In addition, since the metal oxide precursor shrinks in volume when it becomes a metal oxide by heating, the obtained transparent conductive film is further densified, improving the strength and adhesion of the film, and stabilizing the film characteristics. Can be planned.
Moreover, generally a metal oxide precursor is easy to melt | dissolve in a liquid medium compared with the metal oxide mentioned above, and its fluidity | liquidity is high. Therefore, the metal oxide precursor can be suitably used for forming a transparent conductive film on a relatively small member such as a thin film transistor.

  Such precursors include Li, Be, B, Na, Mg, Al, Si, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Nb, Mo, Cd, In, Sn, Sb, Cs, Ba, La, Hf, Ta, W, Tl, Pb, Bi, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Examples thereof include alkoxides and salts such as Ho, Er, Tm, Yb, and Lu, or derivatives and complexes thereof.

Examples of the alkoxide include methoxide, ethoxide, propoxide, isopropoxide, butoxide and the like. Examples of the salt include a halide, a formate, an acetate, a propionate, an oxalate, and a nitrate.
Examples of the derivatives include hydrates, hydroxides obtained by neutralization or hydrolysis, and the like. Examples of the complex include chelate compounds with α- or β-diketones, α- or β-keto acids, α- or β-keto acid esters, amino alcohols, and the like.

These precursors may be used singly or in combination of two or more according to the type of the target metal oxide.
When the indium compound and the organic tin compound are used in combination as the metal oxide precursor, the atomic ratio of indium to tin (indium / tin ratio) is 99/1 to 80/20. Preferably, it is 97/3 to 85/15.

For example, when an alkoxide or salt is used as the metal oxide precursor, an acid catalyst, a base catalyst, or the like that promotes the change (conversion) of the metal oxide precursor to the metal oxide may be added. .
Examples of the acid catalyst include inorganic acids such as hydrochloric acid, nitric acid, boric acid, and borohydrofluoric acid, and organic acids such as acetic acid, trifluoroacetic acid, and p-toluenesulfonic acid.

  Such a metal oxide precursor has a metal oxide content of 0.05 to 1 when all the mixed metal oxide precursors are converted into metal oxides with respect to 1 part by weight of a liquid medium in which the metal oxide is dissolved or dispersed. It is preferable to mix so that it may become 0.9 weight part, and it is more preferable to mix so that it may become 0.1-0.5 weight part. If the amount of the precursor mixed (added amount) is too small, the formed transparent conductive film may be too thin to easily break, or sufficient conductivity as the conductive film may not be obtained. On the other hand, if the amount of the precursor mixed is too large, the transparent conductive film becomes thick and the transmittance decreases, or a dense transparent conductive film is formed by desorption of a large amount of by-products generated by thermal decomposition. May be difficult, or the fluidity of the composition for forming a transparent conductive film may be reduced, making it difficult to prepare the composition for forming a transparent conductive film or to apply (supply) it onto a substrate.

Note that the metal oxide fine particles and the inorganic oxide precursor as described above may be used in combination.
In this case, a precursor can be used as what promotes densification of metal oxide fine particles, for example. That is, the precursor can be used as a densification promoting substance. As a result, the precursor is changed into a metal oxide by heat treatment, and the volume shrinks, and the densification of the metal oxide fine particles is promoted. Thereby, the contact area of metal oxide fine particles increases, As a result, higher electroconductivity is acquired in the obtained transparent conductive film. In addition, since the metal oxide fine particles are densified (the metal oxide density is increased), the obtained transparent conductive film can improve the strength and adhesion of the film and stabilize the film characteristics. .

The metal oxide precursor (densification promoting substance) is preferably blended in an amount of 0.01 to 1 part by weight with respect to 1 part by weight of the metal oxide fine particles described above. It is more preferable to blend so as to be part by weight.
When the precursor functions as a densification accelerating substance, the precursor preferably has a weight reduction rate of 10% or more when heated from room temperature to 400 ° C. (preferably 350 ° C.).

Here, the weight reduction rate is a value calculated by [(weight at room temperature−weight after heating) / weight at room temperature] × 100 (%).
By using a precursor having a weight reduction rate in the above range, densification of metal oxide fine particles can be further promoted, and the formed transparent conductive film can be made more excellent in conductivity.

In the above description, the metal oxide precursor has been described as functioning as a densification accelerating substance. However, the metal oxide precursor may not have such a function.
In addition, although the metal oxide precursor is used as the densification promoting substance, the densification substance may be other than the precursor.
Such a densification promoting substance is preferably a substance that remains so as to fill the voids between the metal oxide fine particles after the transparent conductive film is formed. Thereby, the film | membrane intensity | strength of the formed transparent conductive film can be improved more.

  Further, as such a densification promoting substance, a substance (thermally decomposable substance) that causes a condensation reaction by heating, for example, hydrolysis, thermal decomposition, or the like is preferable. By using a thermally decomposable substance as a densification promoting substance, densification between metal oxide fine particles is promoted in the course of reaction of this thermally decomposable substance, and the reaction product is exchanged between metal oxide fine particles. It remains so as to fill the gap. Thereby, the formed transparent conductive film becomes more excellent in conductivity, film strength and adhesion, and stability of film characteristics.

  Further, the densification promoting substance and the contracted product thereof may be either conductive or non-conductive, but at least in the state of the contracted material ( A conductive material) is preferred. Thereby, the electroconductivity of the formed transparent conductive film can be improved more. Here, the shrinkage of the densification promoting substance refers to a densification promoting substance after being shrunk (changed) by heating.

[Hydrogen fluoride or HF generating material capable of generating hydrogen fluoride]
Generally, an ultrathin film (natural oxide film) formed by natural oxidation exists on the surface of a semiconductor layer made of silicon. When a transparent conductive film is formed as it is on silicon on which a natural oxide film is formed in this way, there is a problem that the conductivity between the semiconductor layer and the transparent conductive film is hindered because the natural oxide film is an insulating film. It was. In order to solve such a problem, the natural oxide film has been removed in advance by a method such as sputter etching before forming the transparent conductive film.

  However, conventional methods such as sputter etching not only remove the natural oxide film on silicon in order to etch the entire surface, but also etch the surface of interlayer insulating films composed of silicon oxide and other parts in the same way. As a result, the surface becomes rough and affects the adhesion to the upper layer film such as a transparent conductive film, resulting in a problem that the reliability of the finally obtained device is lowered.

  Therefore, as a result of intensive studies to solve the above problems, the present inventor has found that a material (HF composition) that can generate hydrogen fluoride or hydrogen fluoride as a material for forming a transparent conductive film (a composition for forming a transparent conductive film). The lower conductive layer (source region) that is electrically bonded to the transparent conductive film as described above by performing detailed temperature control for each step of the etching step, the drying step, and the heat treatment step. It has been found that a transparent conductive film can be easily and reliably formed while selectively removing only the natural oxide film on the surface of the drain region and the like.

Examples of HF generating materials include Li, Be, B, Na, Mg, Al, Si, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Nb, Mo, Cd, In, Sn, Sb, Cs, Ba, La, Hf, Ta, W, Tl, Pb, Bi, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Examples of the metal M fluoride metal salt such as Dy, Ho, Er, Tm, Yb, and Lu (MF _n (n is the valence of M)), ammonium fluoride salt, etc. A combination of the above can be used.

Among these, as the metal fluoride salt, calcium fluoride (CaF ₂ ), indium fluoride (InF ₄ ), tin fluoride, boron fluoride (BF ₃ ), as the ammonium fluoride salt, ammonium fluoride, Preference is given to using ammonium hydrogen fluoride. Thereby, hydrogen fluoride can be generated in the composition for forming a transparent conductive film applied more efficiently.
In addition, you may add solvents, such as water, and catalysts, such as an acid catalyst and a base catalyst, as needed. Thereby, generation | occurrence | production of hydrogen fluoride can be accelerated | stimulated.

The amount of hydrogen fluoride generated from hydrofluoric acid or HF generating material is preferably 1 × 10 ^{−4 to} 5 × 10 ⁻¹ parts by weight with respect to 1 part by weight of the liquid medium as described later. It is more preferable that it is 1 × 10 ^{−3 to} 5 × 10 ⁻² parts by weight. Thereby, the natural oxide film of silicon on the surface of the lower conductive portion that is in contact with the composition for forming a transparent conductive film applied efficiently can be removed. On the other hand, if the amount of hydrogen fluoride is less than the lower limit, it may be difficult to sufficiently remove the natural oxide film of silicon. On the other hand, if the amount of hydrogen fluoride exceeds the upper limit, it becomes difficult to control the etching process, and the problem of excessive etching of the surface of the lower conductive portion occurs, and an effect sufficient to meet the blending amount cannot be obtained. There is a case. In addition, it may be difficult to finally remove hydrogen fluoride completely.

[Liquid medium]
Examples of the liquid medium (liquid that dissolves or disperses the metal oxide fine particles and the metal oxide precursor) include water, methanol, ethanol, n- or i-propanol, n-, s-, or t-butanol. Monohydric alcohols, glycols such as ethylene glycol and trimethylene glycol (polyhydric alcohols), ketones such as acetone, methyl ethyl ketone, diethyl ketone, acetylacetone and isophorone, esters such as methyl acetate, ethyl acetate and butyl acetate , Ether alcohols such as methoxyethanol and ethoxyethanol, ethers such as dioxane and tetrahydrofuran, acid amides, aromatic hydrocarbons, etc., and combinations of one or more of these Can be used.

  Among these, water, alcohols, glycols, and ketones are preferably used as the liquid medium. By using these liquids, the metal oxide fine particles and the like can be dispersed well in the transparent conductive film forming composition, and the solubility of the metal oxide precursor is also good. It is possible to easily and reliably supply (apply) the composition for forming a transparent conductive film.

<Method for forming transparent conductive film>
Next, the formation method of the transparent conductive film of this invention is demonstrated.
In the method for forming a transparent conductive film of the present invention, the transparent conductive film is formed by applying the transparent conductive film forming composition as described above to the surface of the member. Thereby, even if the process of removing the natural oxide film formed on the surface of the lower conductive portion is omitted, a transparent conductive film having a good electrical connection with the lower conductive portion via the contact hole can be easily and easily obtained. Can be formed. In the following description, the transparent conductive film forming composition is described as including both metal oxide fine particles and a precursor thereof (densification promoting substance).
3 and 4 are schematic views for explaining the method for forming a transparent conductive film of the present invention.
The method for forming a transparent conductive film according to this embodiment includes: [1] a mask forming step, [2] a step of applying a composition for forming a transparent conductive film, [3] a heat treatment step of a film, and [4] a mask removing step. And have. Hereinafter, these steps will be sequentially described.

[1] Mask Formation Step First, a member 5 as shown in FIG. This member 5 constitutes the thin film transistor 93 before forming the conductive portion 9352, the conductive portion 9354, and the conductive portion 9356.
Next, a resist film is formed on the member 5 so as to cover the insulating layer 9342. Then, the resist film is irradiated with ultraviolet rays to form a mask (pattern shape control mask) 6E having conductive portion grooves (wiring grooves) 9357 as openings (see FIG. 3B).

In addition, you may perform a liquid repelling process with respect to the mask 6E formed in this way. Thereby, when providing the composition for transparent conductive film formation so that it may mention later, the composition for transparent conductive film formation can be selectively provided to a desired site | part.
Examples of the liquid repellent treatment include a method of exposing to activated carbon generated by carbon tetrafluoride gas, atmospheric pressure plasma, or the like.

  The method for forming the mask is not limited to the above-described method, and examples thereof include wet plating methods such as electrolytic plating, immersion plating, and electroless plating, vacuum deposition, sputtering, thermal CVD, plasma CVD, and laser CVD. Chemical vapor deposition (CVD), gas phase deposition methods such as ion plating (dry plating method), dip coating, doctor blade, spin coating, brush coating, spray coating, electrostatic coating, electrodeposition coating, roll coater, etc. Examples include various coating methods, thermal spraying, joining of metal foils, and polymerization reactions (particularly plasma polymerization) of precursors (monomers, dimers, trimers, oligomers, prepolymers, etc.) corresponding to the constituent materials of the surface layer. .

[2] Step of Applying Composition for Forming Transparent Conductive Film Next, as shown in FIGS. 3C and 4A, the composition for forming a transparent conductive film is applied to the wiring groove 9357, and the film 81 is formed. Form.
The method for applying the transparent conductive film forming composition to the wiring groove 9357 is not particularly limited, and examples thereof include spin coating, dip coating, spray coating, roll coating, screen printing, and inkjet printing. It is preferable to use various coating methods.
According to the coating method, the film 81 having a desired film thickness can be formed relatively easily and accurately.
In addition, the average thickness of the film 81 is appropriately set according to the thickness of the target transparent conductive film, the concentration (content) of the transparent conductive film material in the composition for forming a transparent conductive film to be applied (applied), and the like. Is done.

[3] Heat treatment step for coating Next, heat treatment is performed on the formed coating 81.
In the present embodiment, the first heat treatment step, the second heat treatment step in which the heat treatment is performed at a temperature higher than the heat treatment in the first heat treatment step, and the first heat treatment in the temperature higher than the heat treatment in the second heat treatment step. 3 will be described.

(3-1) First heat treatment step (first heat treatment)
First, a first heat treatment is performed on the film 81 formed as described above.
By performing the first heat treatment, for example, when the composition for forming a transparent conductive film contains an HF generating material capable of generating hydrogen fluoride, hydrogen fluoride is efficiently generated in the coating 81 to form a transparent conductive film. It is possible to selectively remove the natural oxide film 95 on the surface of the lower conductive portion in contact with the composition for use (see FIG. 4B).

Further, when the transparent conductive film forming composition contains hydrogen fluoride, the heat treatment is performed in this manner to activate the hydrogen fluoride in the coating 81 and more efficiently the natural oxide film 95 of silicon. Can be removed.
The heat treatment temperature T ₁ in the first heat treatment step is preferably 20 to 100 ° C., and more preferably 25 to 80 ° C. Thereby, the natural oxide film of silicon can be removed more efficiently. In contrast, there is a case where the temperature T ₁ is is less than the above lower limit value, the time to sufficiently remove the natural oxide film of the silicon becomes longer. On the other hand, when the temperature T ₂ exceeds the upper limit, the hydrogen fluoride scatters in the air from the coating 81, the concentration of hydrogen fluoride in the coating 81 may be reduced. As a result, it may be difficult to sufficiently remove the natural oxide film of silicon.

The time for performing the heat treatment in the first heat treatment step is not particularly limited, but when the heat treatment temperature is in the above range, it is preferably 5 to 600 seconds, and more preferably 30 to 300 seconds. Thereby, the natural oxide film of silicon can be removed more reliably.
Note that the first heat treatment may be performed in any atmosphere such as an oxidizing atmosphere, a reducing atmosphere, or an inert atmosphere.

By the way, it is considered that the natural oxide film of silicon is removed by the reaction shown in the following reaction formula (I).
SiO ₂ + 4HF → SiF ₄ + 2H ₂ O (I)
Since SiF ₄ generated by this reaction is a gas, it can be prevented from remaining in the finally obtained transparent conductive film.

(3-2) Second heat treatment step (second heat treatment)
Next, the coating 81 is subjected to a second heat treatment at a temperature higher than that of the first heat treatment step.
By performing such a second heat treatment, for example, the film 81 can be dried and a part or all of the liquid medium can be removed. Further, hydrogen fluoride and the like in the film 81 can be effectively removed (see FIG. 4C).

Temperature (drying temperature) T ₂ for drying the coating 81 is suitably set according to the type of the liquid medium is not particularly limited, but is preferably 20 to 200 ° C., and even at 50 to 150 ° C. More preferred. Thereby, hydrogen fluoride, a liquid medium, etc. can be removed more reliably, suppressing the quality change of a transparent conductive film material, etc.
Further, when T _{1 is} the temperature of the heat treatment in the first heat treatment step and T ₂ is the temperature of the heat treatment in the second heat treatment step, it is preferable that the relationship of T ₂ > T ₁ +20 is satisfied, and T ₁ +20 It is more preferable to satisfy the relationship of <T ₂ <T ₁ +100. By satisfying such a relationship, hydrogen fluoride, a liquid medium, or the like can be more reliably removed while suppressing deterioration or the like of the transparent conductive film material.

Also, the time for drying the coating 81 is not particularly limited, but when the drying temperature is in the above range, it is preferably 1 to 40 minutes, and more preferably 1 to 20 minutes. Thereby, hydrogen fluoride, a liquid medium, etc. can be removed more reliably.
In the second heat treatment step, by appropriately setting the drying temperature, the drying time, and the like and adjusting the drying speed of the coating 81, the metal oxide fine particles are arranged in an orderly manner (arranged) in the coating 81 after drying. And the densification of the inorganic oxides can proceed more reliably by the heat treatment in the third heat treatment step described later.

From this point of view, in the application process of the composition for forming a transparent conductive film, and in the first heat treatment process and the second heat treatment process, the coating film 81 is subjected to vibration while applying, for example, ultrasonic waves. May be.
The second heat treatment may be performed in any atmosphere such as an oxidizing atmosphere, a reducing atmosphere, or an inert atmosphere. Further, the second heat treatment may be performed in a vacuum or under reduced pressure as necessary. Thereby, hydrogen fluoride and a liquid medium can be efficiently removed under lower temperature conditions.

(3-3) Third heat treatment step (third heat treatment)
Next, the dried film 81 is subjected to a third heat treatment (for example, baking) to be cured (solidified). Thereby, the transparent conductive film (conductive part 9352, conductive part 9354) of the present invention as shown in FIG. 2 is obtained.
When this third heat treatment is performed, as shown in FIG. 4D, the precursor 8 buried in the gap between the metal oxide fine particles shrinks in volume, and this shrinkage densifies the metal oxide fine particles 7 together. As a result, the density of the transparent conductive film increases. At this time, since the metal oxide fine particles 7 are fixed to each other (sintered), the adhesiveness and hardness of the transparent conductive film are further increased.

Even if the surface is rough as shown in FIG. 4C, the surface can be flattened by performing such heat treatment.
For example, when a metal alkoxide is used as the precursor 8, the metal alkoxide is hydrolyzed by heating to produce an alcohol and a metal hydroxide. Further, a condensation reaction occurs in the metal hydroxide, thereby generating a metal oxide (precursor shrinkage 8 ′).

In the course of this reaction, densification between the metal oxide fine particles 7 (shrinkage of the coating 81) is promoted, and the generated metal oxide (precursor shrinkage 8 ') is a void between the metal oxide fine particles 7. Fill. As a result, the contact area between the metal oxide fine particles 7 is increased, and the metal oxide filling the voids also has conductivity, so that it is more excellent in conductivity, film strength and adhesion, and stability of film characteristics. Transparent conductive films (conductive portion 9352, conductive portion 9354, and conductive portion 9356) are obtained.
The temperature T3 of the _third heat treatment is not particularly limited, but is preferably 50 to 500 ° C, and more preferably 150 to 350 ° C. If the heating temperature is too low, there is a possibility that the adhesion between the metal oxide fine particles 7 and the volume shrinkage of the precursor 8 do not proceed sufficiently. On the other hand, even if the temperature of the heat treatment exceeds the upper limit, no further effect can be expected.

Further, when T _{2 is} the temperature of the heat treatment in the second heat treatment step and T ₃ is the temperature of the heat treatment in the third heat treatment step, it is preferable to satisfy the relationship of T ₃ > T ₂ +50, and T ₂ +50 It is more preferable to satisfy the relationship of <T ₃ <T ₂ +300. By satisfying such a relationship, hydrogen fluoride, liquid medium, etc. remaining on the coating 81 are more reliably removed, and adhesion between the metal oxide fine particles 7 and volume shrinkage of the precursor 8 are sufficiently advanced. Can be made.
Moreover, the time (heating time) of the third heat treatment is not particularly limited, and when the heating temperature is within the above range, it is preferably 1 to 180 minutes, and more preferably 5 to 120 minutes. With the heating time in the above range, the adhesion between the metal oxide fine particles 7 and the shrinkage of the precursor 8 can be sufficiently advanced.

Further, the atmosphere in the third heat treatment may be any of an oxidizing atmosphere, a non-oxidizing atmosphere, and a reducing atmosphere. Moreover, you may carry out under a vacuum or pressure reduction state as needed.
Note that the third heat treatment may be repeated a plurality of times, and in this case, the heat treatment conditions in each heat treatment may be the same or different.

[4] Mask Removal Step Next, the mask 6E is removed. Thereby, a thin film transistor as shown in FIG. 2 is obtained.
The removal of the mask 6E may be performed by any method. For example, ashing under an atmospheric pressure or reduced pressure using ultraviolet plasma or ozone, ultraviolet rays, Ne-He laser, Ar laser, CO ₂ laser , Irradiation with various lasers such as ruby laser, semiconductor laser, YAG laser, glass laser, YVO ₄ laser, and excimer laser, immersion in an organic solvent or inorganic solution capable of dissolving and decomposing the mask 6E, and the like.

Although the present embodiment has been described as having a mask removal step, the mask removal step may be omitted depending on the use of a member obtained by applying the present invention.
As described above, in the method for forming a transparent conductive film according to the present invention, the transparent conductive film is formed while gradually treating the natural oxide film of silicon by a wet process, so that cost and energy are wasted by simple equipment and processes. A transparent conductive film can be formed.
Accordingly, by forming each conductive portion of the liquid crystal panel shown in FIG. 1 using such a composition for forming a transparent conductive film and a method for forming the transparent conductive film, various characteristics such as driving performance and durability of the liquid crystal are formed. Can be manufactured at low cost.

<Electronic equipment>
The electronic device of the present invention can be used for display portions of various electronic devices.
FIG. 5 is a perspective view showing a configuration of a mobile (or notebook) personal computer to which the electronic apparatus of the present invention is applied.
In this figure, a personal computer 1100 includes a main body 1104 having a keyboard 1102 and a display unit 1106. The display unit 1106 is supported by the main body 1104 via a hinge structure so as to be rotatable. Yes.
In the personal computer 1100, the display unit 1106 includes the liquid crystal panel (electro-optical device) 100 described above.

FIG. 6 is a perspective view showing a configuration of a mobile phone (including PHS) to which the electronic apparatus of the present invention is applied.
In this figure, a cellular phone 1200 includes a plurality of operation buttons 1202, an earpiece 1204, and a mouthpiece 1206, and the above-described liquid crystal panel (electro-optical device) 100 in a display unit.

FIG. 7 is a perspective view showing the configuration of a digital still camera to which the electronic apparatus of the present invention is applied. In this figure, connection with an external device is also simply shown.
Here, an ordinary camera sensitizes a silver halide photographic film with a light image of a subject, whereas a digital still camera 1300 photoelectrically converts a light image of a subject with an imaging device such as a CCD (Charge Coupled Device). An imaging signal (image signal) is generated.

The above-described liquid crystal panel 100 is provided on the back of a case (body) 1302 in the digital still camera 1300, and is configured to display based on an image pickup signal from the CCD, and displays the subject as an electronic image. Functions as a finder.
A circuit board 1308 is installed inside the case. The circuit board 1308 is provided with a memory that can store (store) an imaging signal.

A light receiving unit 1304 including an optical lens (imaging optical system), a CCD, and the like is provided on the front side of the case 1302 (on the back side in the illustrated configuration).
When the photographer confirms the subject image displayed on the liquid crystal panel 100 and presses the shutter button 1306, the image pickup signal of the CCD at that time is transferred and stored in the memory of the circuit board 1308.

  In the digital still camera 1300, a video signal output terminal 1312 and an input / output terminal 1314 for data communication are provided on the side surface of the case 1302. As shown in the figure, a television monitor 1430 is connected to the video signal output terminal 1312 and a personal computer 1440 is connected to the data communication input / output terminal 1314 as necessary. Further, the imaging signal stored in the memory of the circuit board 1308 is output to the television monitor 1430 or the personal computer 1440 by a predetermined operation.

  The electronic apparatus of the present invention includes, for example, a television, a video camera, a viewfinder type, in addition to the personal computer (mobile personal computer) in FIG. 3, the mobile phone in FIG. 4, and the digital still camera in FIG. Monitor direct-view video tape recorder, laptop personal computer, car navigation system, pager, electronic notebook (including communication function), electronic dictionary, calculator, electronic game device, word processor, workstation, video phone, security TV Monitors, electronic binoculars, POS terminals, devices equipped with touch panels (for example, cash dispensers and automatic ticket vending machines for financial institutions), medical devices (for example, electronic thermometers, blood pressure monitors, blood glucose meters, electrocardiographs, ultrasound diagnostic devices, internal Endoscope display device), fish finder, various measuring instruments, Vessels such (e.g., gages for vehicles, aircraft, and ships), a flight simulator, various monitors, and a projection display such as a projector.

As mentioned above, although the composition for transparent conductive film formation of this invention, the formation method of a transparent conductive film, a transparent conductive film, an electronic device, and an electronic device were demonstrated based on embodiment of illustration, this invention is limited to these. It is not a thing.
For example, in the composition for forming a transparent conductive film of the present invention, various additives may be added as necessary.

Moreover, in the method for forming a transparent conductive film of the present invention, one or two or more optional steps may be added.
In the embodiment described above, the case where each conductive portion of the thin film transistor 93 is formed using the composition for forming a transparent conductive film has been described. However, the present invention is not limited thereto, and for example, the transparent conductive film 14 and the pixel electrode 92 are formed. The composition for forming a transparent conductive film of the present invention can also be applied in the case of forming the like.

Further, the composition for forming a transparent conductive film of the present invention is not limited to the one formed on the semiconductor layer composed only of silicon, and may be formed mainly on the semiconductor layer composed of silicon. . As a semiconductor layer mainly composed of silicon, for example, a layer into which an impurity such as a p-type impurity is introduced can be given.
In the above-described embodiment, the heat treatment process has been described as having three processes. However, the present invention is not limited to this, and such a heat treatment process may be performed in one process. It may be performed in one process, or may be performed in four or more processes. Further, such a heat treatment step may be omitted. Further, the heat treatment temperature in each heat treatment step may be constant during each step, or may vary.
Furthermore, in the electronic device and the electronic apparatus of the present invention, the configuration of each part can be replaced with any configuration that exhibits the same function, and any configuration can be added.

Next, specific examples of the present invention will be described.
A. Transparent conductive film In Examples 1 to 3 and Comparative Examples 1 to 3, a transparent conductive film was formed on the member shown in FIG.
(Example 1)
<1-1> The member shown to Fig.3 (a) was prepared.
Thereafter, a mask was formed on the member using the method described above.

<1-2> Next, using a water + ethanol mixed liquid (water / ethanol (weight ratio) = 8/2) as a liquid medium, ITO particles (average particle diameter: 20 nm), indium chloride are added to the liquid medium. Then, tin chloride and ammonium fluoride were mixed so as to have the following mixing ratios to prepare a composition for forming a transparent conductive film.
ITO particles: 0.1 parts by weight with respect to 1 part by weight of liquid medium Indium chloride: 0.7 parts by weight with respect to 1 part by weight of ITO particles Tin chloride: 0.04 parts by weight with respect to 1 part by weight of ITO particles,
Indium / tin (atomic ratio) = 93/7
Ammonium fluoride: 3 × 10 ⁻³ parts by weight with respect to 1 part by weight of liquid medium (approx. 2 × 10 ⁻³ parts by weight as hydrogen fluoride generation amount (estimated from the etching rate of silicon oxide film))
In addition, when a mixture (densification promoting substance) in which indium chloride and tin chloride are mixed at indium / tin (weight ratio) = 0.7 / 0.04 is heated from room temperature to 350 ° C., the weight reduction rate Was 10% or more.
Further, ITO particles having indium / tin (atomic ratio) = 94/6 were used.

<1-3> Next, this composition for forming a transparent conductive film was applied onto a member by a spin coating method to form a film.
The number of rotations of the member was 2000 rpm.
<1-4> Next, the obtained coating film was subjected to heat treatment (first heat treatment) in air (oxidizing atmosphere) under the conditions of a temperature of 50 ° C. and a time of 100 seconds.

  <1-5> Next, the coating film subjected to the first heat treatment was dried (second heat treatment) in air (oxidizing atmosphere) at a temperature of 100 ° C. for 5 minutes.

<1-6> Next, the dried film was subjected to heat treatment (third heat treatment) in a nitrogen atmosphere (non-oxidizing atmosphere) under conditions of a temperature of 400 ° C. and a time of 60 minutes. Thereby, a transparent conductive film was obtained.
In the transparent conductive film, ITO particles: ITO (constriction of densification promoting substance) = 1: 0.2 (weight ratio).
<1-7>
Next, the mask was irradiated with ultraviolet rays to decompose and remove the mask.

(Example 2)
<2-1> A member shown in FIG.
Thereafter, a mask was formed on the member using the method described above.
<2-2> Next, using ethanol as a liquid medium, ATO particles (average particle size: 100 nm), di-n-butyltin-di-acetate (organotin compound) and antimony chloride, 50 wt% are added to the ethanol. (Concentration) hydrofluoric acid (hydrogen fluoride + water) was mixed so as to have the following mixing ratios to prepare a transparent conductive film forming composition.
ATO particles: 0.3 parts by weight with respect to 1 part by weight of liquid medium Organotin compound: 0.5 parts by weight with respect to 1 part by weight of ATO particles Antimony chloride: 0.15 parts by weight with respect to 1 part by weight of ATO particles
Tin / antimony (atomic ratio) = 80/20
Hydrofluoric acid: 2.5 × 10 ⁻³ parts by weight (about 2.5 × 10 ⁻³ parts by weight of hydrogen fluoride generation) with respect to 1 part by weight of the liquid medium

In addition, the mixture (densification promoting substance) obtained by mixing an organotin compound and antimony chloride at a ratio of tin / antimony (weight ratio) = 0.5 / 0.15 is heated from room temperature to 500 ° C., and its weight decreases. The rate was 10% or more.
As the ATO particles, those having tin / antimony (atomic ratio) = 80/20 were used.

<2-3> Next, this composition for transparent conductive film formation was apply | coated on the member with the spin coat method, and the film was formed.
The number of rotations of the member was 2000 rpm.
<2-4> Next, the obtained coating film was subjected to heat treatment (first heat treatment) in the atmosphere (oxidizing atmosphere) under conditions of a temperature of 30 ° C. and a time of 120 seconds.

<2-5> Next, the coating film subjected to the first heat treatment was dried (second heat treatment) in air (oxidizing atmosphere) at a temperature of 80 ° C. for 5 minutes.
<2-6> Next, the dried film was subjected to heat treatment (third heat treatment) in a nitrogen atmosphere (non-oxidizing atmosphere) under conditions of a temperature of 500 ° C. and a time of 60 minutes. Thereby, a transparent conductive film was obtained.
In the transparent conductive film, ATO particles: ATO (constriction of densification promoting substance) = 1: 0.38 (weight ratio).

(Comparative Example 1)
A transparent conductive film was formed using the composition for forming a transparent conductive film prepared in the same manner as in Example 1 except that ammonium fluoride was not used.
(Comparative Example 2)
First, the member shown to Fig.3 (a) was prepared.

Next, wet etching was performed using 2 wt% hydrofluoric acid (hydrogen fluoride + water) in air (oxidizing atmosphere) at a temperature of 20 ° C. for 20 seconds to remove the natural oxide film.
Next, an ITO film was formed on the surface of the member subjected to the treatment for removing the natural oxide film by sputtering.
Next, a resist film was applied to the surface of the formed ITO film, and subjected to photosensitivity, development, and etching to form a mask corresponding to a portion where a transparent conductive film was to be formed.

Next, etching was performed using the mask to remove the ITO film not covered with the mask.
Thereafter, the mask was removed, and a transparent conductive film was formed.
In addition, when the surface of the member after wet etching was observed, sputter etching was performed also on the unintended portion, and the surface was rough as a whole.

[Evaluation]
About the transparent conductive film formed in each Example and each comparative example, each contact resistance value with a semiconductor layer was measured, and 10 average values were calculated | required, respectively. The contact resistance value was measured using a 4-probe method (JIS K7191).
The results are shown in Table 1.

As shown in Table 1, the transparent conductive film of each example had a low contact resistance value and excellent conductivity with respect to each corresponding comparative example.
In particular, even when compared with Comparative Example 2 in which the natural oxide film was removed, the transparent conductive film of each Example exhibited excellent contact resistance values. This is because when hydrogen fluoride is added to the surface of the metal oxide fine particles in the composition for forming a transparent conductive film and this is removed by heat treatment, the bonding property between the transparent conductive film and the semiconductor layer and the transparent conductive film This is probably because the densification was improved.
In addition, the transparent conductive film of Comparative Example 1 exhibited a high contact resistance value as shown in Table 1, and variation in the contact resistance value was confirmed depending on the measurement site.

B. Liquid Crystal Panel Next, a liquid crystal panel as shown in FIG. 1 was manufactured using the thin film transistors in which the transparent conductive films of Examples 1 and 2 and Comparative Examples 1 and 2 were formed.
All of the liquid crystal panels having the transparent conductive film of Examples 1 and 2 had a high response speed and no color unevenness was observed. Further, these liquid crystal panels showed excellent performance even when compared with a liquid crystal panel formed in the same manner as in Comparative Example 2.

On the other hand, all of the liquid crystal panels in which the transparent conductive film was formed in the same manner as in Comparative Example 1 had an increased CR time constant specific to the liquid crystal element and a long response time to the image signal (low response speed). there were. In addition, color unevenness occurred.
Furthermore, such a phenomenon became remarkable over time.

It is a typical longitudinal section showing a suitable embodiment of a liquid crystal panel (electronic device) of the present invention. It is an expanded sectional view of the vicinity of the thin film transistor of the liquid crystal panel shown in FIG. It is a schematic diagram for demonstrating the formation method of the transparent conductive film of this invention. It is a schematic diagram for demonstrating the formation method of the transparent conductive film of this invention. 1 is a perspective view showing a configuration of a mobile (or notebook) personal computer to which an electronic apparatus of the present invention is applied. It is a perspective view which shows the structure of the mobile telephone (PHS is also included) to which the electronic device of this invention is applied. It is a perspective view which shows the structure of the digital still camera to which the electronic device of this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Liquid crystal panel 2 ... Liquid crystal layer 3, 3 '... Orientation film 4, 4' ... Polarizing film 5 ... Member 6E ... Mask 7 ... Metal oxide fine particle 8 ... Precursor 8 '... Precursor shrinkage 81... Coating 9... TFT substrate 91... Glass substrate 92... Pixel electrode 93... Thin film transistor 9314... Semiconductor layer (polycrystalline silicon film) 9316 ... Source region 9318 ... Drain region 9320 ... Channel region 9326 ... Gate insulating film 9332 ... Trench for gate electrode 9336 ... Resist film 9342 ... Insulating layer 9351 ... Gate electrode 9352 ... Conductive part 9354 ... Conductive part 9356 ... Conductive part 9357 ... Conductive part groove (wiring groove) 94... Base insulating film 11... Microlens substrate 111... Substrate with recess for microlens 112. 3 ... Micro lens 114 ... Surface layer 115 ... Resin layer 12 ... Counter substrate for liquid crystal panel 13 ... Black matrix 131 ... Opening 14 ... Transparent conductive film 1100 ... Personal computer 1102 ... Keyboard 1104 ... Main body 1106 ... Display unit 1200 ... Mobile phone 1202 ... Operation buttons 1204 ... Earpiece 1206 ... Mouthpiece 1300 ... Digital still camera 1302 ... Case (body) 1304 ... Light receiving unit 1306 ... Shutter button 1308 ... Circuit board 1312 ... Video signal output terminal 1314 ... Input / output terminal for data communication 1430 ... Television monitor 1440 ... Personal computer

Claims (27)

A composition for forming a transparent conductive film used for forming a transparent conductive film,
A transparent conductive film material composed of conductive metal oxide fine particles and / or precursors thereof; and
Hydrogen fluoride or an HF generating material capable of generating hydrogen fluoride;
A composition for forming a transparent conductive film, comprising at least a liquid medium in which a part of the transparent conductive film material is dissolved or dispersed. 2. The amount of hydrogen fluoride generated from the hydrogen fluoride or the HF generating material is 1 × 10 ^{−4 to} 5 × 10 ⁻¹ parts by weight with respect to 1 part by weight of the liquid medium. A composition for forming a transparent conductive film.   The composition for forming a transparent conductive film according to claim 1, comprising a densification promoting substance that shrinks by heating and promotes densification of the metal oxide fine particles.   The composition for forming a transparent conductive film according to claim 3, wherein the densification accelerating substance has a weight reduction rate of 10% or more when heated from room temperature to 400 ° C.   The composition for forming a transparent conductive film according to claim 3 or 4, wherein the densification promoting substance has a conductive contraction. The transparent conductive film material contains metal oxide fine particles,
6. The densification promoting substance is mixed in the formed transparent conductive film so that the shrinkage is 0.01 to 1 part by weight with respect to 1 part by weight of the metal oxide fine particles. The composition for transparent conductive film formation in any one of.   The composition for forming a transparent conductive film according to claim 3, wherein the densification promoting substance is the precursor, and at least a part of the precursor is changed to a metal oxide by the heating. The transparent conductive film material contains metal oxide fine particles,
The transparent conductive material according to any one of claims 3 to 7, wherein the metal oxide obtained by heating the densification promoting substance and the metal oxide fine particles as the main material of the transparent conductive film material are of the same type. Film forming composition.   The composition for forming a transparent conductive film according to claim 1, wherein the metal oxide fine particles have an average particle size of 2 to 2000 nm.   The composition for forming a transparent conductive film according to any one of claims 1 to 9, wherein the metal oxide fine particles are mixed so as to be 0.05 to 0.9 parts by weight with respect to 1 part by weight of the liquid medium. Stuff. A method of forming a transparent conductive film on a surface of a member made of silicon at least a part near the surface,
A method for forming a transparent conductive film, comprising the step of applying the composition for forming a transparent conductive film according to claim 1 to the surface of the member.   The method for forming a transparent conductive film according to claim 11, wherein the member has a film mainly composed of silicon, and the composition for forming the transparent conductive film is applied to at least the film.   The method for forming a transparent conductive film according to claim 11, comprising at least one heat treatment step after the applying step.   The method for forming a transparent conductive film according to claim 13, wherein the heat treatment step includes a first heat treatment step and a second heat treatment step in which the heat treatment is performed at a higher temperature than the heat treatment of the first heat treatment step. T ₁ the temperature of the heat treatment in the first heat treatment _step, when the temperature of heat treatment in the second heat treatment step was set to T _2, the transparent conductive according to claim 14 which satisfies the relation of T _{2> T} 1 ₊₂₀ Method for forming a film. The first heat treatment temperature T ₁ of the heat treatment in the step is a method of forming the transparent conductive film according to claim 14 or 15 is 20 to 100 ° C.. The temperature T ₂ of the heat treatment in the second heat treatment step, the method of forming the transparent conductive film according to any one of claims 14 to 16 is 20 to 200 ° C..   The method for forming a transparent conductive film according to claim 14, wherein the heat treatment step further includes a third heat treatment step in which the heat treatment is performed at a higher temperature than the heat treatment in the second heat treatment step. T ₂ the temperature of the heat treatment in the second heat treatment _step, when the temperature of heat treatment in the third heat treatment step was set to T _3, the transparent conductive according to claim 18 which satisfies the relation of T _{3> T} 2 ₊₅₀ Method for forming a film. The third temperature T ₃ of the heat treatment in the heat treatment step of the method for forming a transparent conductive film according to claim 18 or 19 is 50 to 500 ° C..   The method for forming a transparent conductive film according to claim 14, wherein the time in the first heat treatment step is 10 seconds to 600 seconds.   The method for forming a transparent conductive film according to any one of claims 14 to 21, wherein a time in the second heat treatment step is 1 to 40 minutes.   The method for forming a transparent conductive film according to claim 18, wherein the time in the third heat treatment step is 1 to 180 minutes.   It forms with the formation method of the transparent conductive film in any one of Claim 11 thru | or 23, The transparent conductive film characterized by the above-mentioned. The transparent conductive film is connected to the semiconductor layer,
The transparent conductive film according to claim 24, wherein a contact resistance value between the transparent conductive film and the semiconductor layer is 100 kΩ or less.   An electronic device comprising the transparent conductive film according to claim 24 or 25. An electronic apparatus comprising the electronic device according to claim 26.

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