JP2004156057A - Method for depositing carbon thin film, and carbon thin film obtained thereby - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film deposition method where the deposition of a carbon thin film which has uniform pretilt angle or tilt angle and includes carbons having columnar structure, and the impartation of orientation properties thereto are simultaneously performed, and to provide a carbon thin film obtained thereby. <P>SOLUTION: Carbon atoms, carbon atoms obtained from an evaporation source of carbon ions, and carbon ions are made incident on the surface of a base material at a prescribed incident angle to deposit a film, so that the carbon thin film comprising carbon with a columnar structure in which the pretilt angle or tilt angle is controlled to a prescribed value in the structure is deposited. The carbon thin film is used as a liquid crystal orientation film, a field electron emission electrode film or the like. <P>COPYRIGHT: (C)2004,JPO

Description

【００２２】
上記成膜プロセスにより得られた炭素薄膜の電界電子放出特性を図７に示す。図中、曲線ａは上記成膜プロセスにより得られた炭素薄膜についての特性、また、曲線ｂは従来の熱ＣＶＤ法により得られた垂直配向ＣＮＴ膜の特性である。これらの曲線から、電界電子放出特性について、本発明の方法を用いて得られた炭素薄膜の方が従来の場合よりも優れていることが分かる。
【００２３】
【発明の効果】
本発明の炭素薄膜形成方法によれば、炭素原子、炭素イオンを所定の入射角範囲で基材表面に入射し、成膜し、組織中に柱状構造の炭素を含む薄膜を形成しているので、プレティルト角又は傾斜角度が所定の値に制御された柱状構造の炭素を組織中に含む炭素薄膜を形成することができる。単純な搬送成膜により、大面積基材上にプレティルト角・傾斜方向とも均一性のよい柱状の微細構造を有する炭素薄膜を形成することができる。
また、本発明の炭素薄膜によれば、所定の値に制御されたプレティルト角又は傾斜角を有する柱状構造の炭素が組織中に含まれているので、例えば、液晶ディスプレー装置の配向膜としての特性や、電界放出型ディスプレー装置の電界電子放出電極膜としての電界電子放出特性に優れている
【００２４】
本発明炭素薄膜形成方法の効果について、以下、さらに詳細に説明する。
（１）ラビング法を用いずに液晶ディスプレー装置の配向膜形成することができるので、画素へのダスト付着・ラビング用布のメンテナンス等の問題が解消される。
（２）液晶ディスプレー装置の配向膜形成において、成膜と配向性付与を同時に行うことができるので、配向膜の製造工程が短縮される。
（３）液晶ディスプレー装置の配向膜、及び電界放出型ディスプレー装置の電界電子放出電極膜等の柱状構造の炭素を含む炭素薄膜の形成において、従来型の斜方蒸着と比較して簡便なプロセスで、均一性のよいプレティルト角又は傾斜角度を持つ柱状構造の炭素を含む大面積炭素薄膜を製造することができる。
（４）電界電子放出電極膜を形成する際に、従来の垂直配向のＣＮＴを製造する場合と比べて、基材材質の種類に関係なく、電極膜を形成できる工程を実現することができ、また、膜の電界電子放出特性を向上させることができる。
【図面の簡単な説明】
【図１】本発明に係わる炭素薄膜形成方法を実施するための一成膜装置の概略の構成を示す断面図。
【図２】本発明に係わる炭素薄膜形成方法を実施するための別の成膜装置の概略の構成を示す断面図。
【図３】本発明に係わる炭素薄膜形成方法を実施するためのさらに別の成膜装置の概略の構成を示す断面図。
【図４】本発明に係わる炭素薄膜形成方法による基材上への成膜中の炭素の柱状構造の成長モデルを説明するための模式図。
【図５】本発明に係わる炭素薄膜形成方法における入射角（θｉ）とプレティルト角（θｐ）との関係を示すグラフ。
【図６】本発明に係わる炭素薄膜形成方法（ただし、遮蔽板を設けない装置を使用）により形成される炭素薄膜の断面のモデルを示す断面図。
【図７】本発明に係わる炭素薄膜形成方法により得られた炭素薄膜の電界電子放出特性を示すグラフ。
【符号の説明】
１ マグネトロンスパッタカソード ２ 基材
３ 遮蔽板 ４ 基材トレー
５ 基材搬送機構のレール ６ 真空槽
７ 排気装置 ８ カソード用電源
９、１０ 入射炭素粒子の経路 １１、１２ 炭素粒子
１３、１４ 炭素粒子の柱状構造 Ｔ ターゲット
ｈ ターゲット中心から基材までの垂直距離
Ｌ ターゲット表面から開口中心までの水平距離
θ１、θ２、θｉ 炭素粒子の入射角 θｐ プレティルト角[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of forming a carbon thin film and the obtained carbon thin film, and more particularly to a method of forming a carbon thin film used as a liquid crystal alignment film in a liquid crystal display device, a field electron emission electrode film in a field emission display device, and the like. The present invention relates to a carbon thin film obtained by this method.
[0002]
[Prior art]
(1) In a liquid crystal display device, an alignment film having an anchoring energy is generally provided on the side in contact with the liquid crystal in order to give a uniform molecular alignment state to the liquid crystal filled between the glass substrates provided opposite to each other. Provided. Conventionally, a method of applying and curing a polyimide film on a glass substrate to give orientation by a rubbing method has been widely used. The rubbing method has problems such as generation of minute dust on the pixel surface, necessity of maintenance of a rubbing cloth, and a large part of the experience of fine adjustment of the process.
[0003]
In order to solve the problem of the rubbing method, a method has been developed in which an amorphous carbon (hereinafter a-C) film is formed, and the film is irradiated with an ion beam to impart orientation. reference). This method requires a two-stage process of film formation and orientation control. Further, in order to simultaneously provide orientation during the film formation stage, a method of obliquely depositing SiO or SiO ₂ or the like (for example, see Patent Document 2), or a method of forming an insulating film such as SiO ₂ substantially parallel to the substrate is used. For example, a method of manufacturing a film having a microstructure by the self-shadowing effect by making the light incident on a substrate (see, for example, Patent Document 3) has been developed. In the case of films obtained by these methods, the pretilt angle and the tilt direction of the columnar structure over the entire surface of the substrate are not uniform. Note that in order to increase the controllability of the pretilt angle, a complicated process such as rotating the substrate while changing the rotation angular velocity during vapor deposition is required, and it is difficult to form a film on a large-area substrate.
[0004]
(2) As one of the structures of the electron emission electrode film of the field emission display device, an aC or Si thin film having a columnar fine structure oriented in a direction perpendicular to the screen has been developed. In order to obtain carbon, there is a problem in oblique deposition described in the above item (1). As another method, a method has been developed in which carbon nanotubes (hereinafter referred to as CNTs) are grown perpendicularly to a substrate surface by a thermal CVD method using a hydrocarbon gas or the like as a raw material. In addition, there is a problem that the CNT is inferior to the deposited film using the solid evaporation source in mechanical strength and electrical conductivity of the CNT.
[0005]
[Patent Document 1]
JP-A-11-271774 (claims 9, 17 and 18 etc.)
[Patent Document 2]
JP-A-53-82440 (Claims)
[Patent Document 3]
JP-A-63-151926 (Claims)
[0006]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide orientation at the same time as film formation, and to provide a columnar structure having good uniformity in both pretilt angle and tilt direction (tilt angle) in a structure. The present invention provides a method for forming a carbon thin film containing carbon and the obtained carbon thin film, and as a result, simplifies the manufacturing steps of a liquid crystal display device, a field emission display device, and the like.
[0007]
[Means for Solving the Problems]
The method for forming a carbon thin film according to the present invention is a method for forming a carbon thin film on a surface of a base material, the method comprising: A film is formed by forming a carbon thin film having a columnar structure in which the pretilt angle or the inclination angle is controlled to a predetermined value in a structure. According to the present invention, it is possible to form a carbon thin film having a columnar fine structure with good uniformity in both the pretilt angle and the tilt direction on a large-area substrate by a simple transfer film formation.
[0008]
This carbon thin film can be used, for example, as a liquid crystal alignment film or a field electron emission electrode film.
The incident angle is preferably from 10 to 80 °, and the pretilt angle or the inclination angle is preferably from 5 to 90 °. When the incident angle is less than 10 °, the growth of the columnar structure is impossible, and when it is more than 80 °, the dynamic film forming rate is low, which is impractical. On the other hand, when the pretilt angle is less than 5 °, an alignment domain is generated, which makes the liquid crystal alignment film unsuitable.
[0009]
The carbon atoms and carbon ions used in the above forming method are obtained from an evaporation source arranged at a predetermined angle with respect to the substrate surface.
The carbon atoms and carbon ions thus obtained from the evaporation source pass through the opening of the shielding plate arranged in parallel with the substrate surface between the substrate surface and the evaporation source, and have a predetermined inclination angle on the substrate surface. Incident.
During the film formation, the film is formed while moving the substrate linearly and parallel to the substrate surface.
The evaporation source used in the formation method of the present invention is preferably a solid evaporation source such as a target, and carbon atoms and carbon ions incident on the surface of the substrate are recoiled from this evaporation source.
[0010]
As the evaporation source, it is preferable to use an evaporation source whose evaporation surface is arranged to have an inclination angle of 10 to 80 ° with respect to the film formation surface of the substrate. If it is less than 10 °, growth of the columnar structure is impossible, and if it is more than 80 °, the film formation rate is low, which is impractical.
According to the carbon thin film forming method of the present invention, since the alignment film of the liquid crystal display device can be formed without using a rubbing method, problems such as dust adhesion to pixels and maintenance of a rubbing cloth are solved, Further, in the formation of the alignment film, the film formation and the imparting of the orientation can be performed at the same time, so that the manufacturing process of the alignment film is shortened. In addition, in forming an alignment film of a liquid crystal display device, and a carbon thin film containing columnar carbon such as a field electron emission electrode film of a field emission display device, a simple process compared to conventional oblique deposition, A large-area carbon thin film containing carbon having a columnar structure having a pretilt angle or a tilt angle with good uniformity can be manufactured.
[0011]
Further, when forming a field electron emission electrode film, a process capable of forming an electrode film can be realized irrespective of the type of the base material, as compared with the case of manufacturing conventional vertically aligned CNTs. The field emission characteristics of the film can be improved.
The carbon thin film of the present invention was formed by depositing carbon atoms and carbon ions obtained from an evaporation source of carbon ions and carbon ions at a predetermined incident angle on the substrate surface, and was controlled to a predetermined value. The structure contains carbon having a columnar structure having a pretilt angle or an inclination angle, and this carbon thin film can be used as a liquid crystal alignment film or a field electron emission electrode film. Further, this carbon thin film is obtained according to the method described above.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
According to the embodiment of the method of forming a carbon thin film according to the present invention, carbon atoms and carbon ions recoiled from a solid evaporation source arranged at a predetermined angle with respect to the substrate surface are used as bases. The light is incident on the surface of the base material at a predetermined inclination angle through an opening of a shielding plate arranged between the material surface and the evaporation source in parallel with the base material surface. The opening provided in the shielding plate preferably has a narrow width in the transport direction and has a longitudinal direction perpendicular to the transport direction.
The substrate used in the method for forming a carbon thin film of the present invention is not particularly limited, and may be a normal substrate or a substrate having a three-dimensional shape, such as an alignment film in a liquid crystal display device. It may have a transparent electrode or the like.
[0013]
Hereinafter, various film forming apparatuses for performing the method of forming a carbon thin film according to the present invention will be described with reference to FIGS.
1 to 3, reference numeral 1 denotes a magnetron sputtering cathode provided with a carbon target T, 2 denotes a substrate, 3 denotes a shielding plate having an opening, 4 denotes a substrate tray, 5 denotes a rail of a substrate transport mechanism, and 6 denotes a vacuum chamber. , 7 indicate an exhaust device, 8 indicates a cathode power supply, and 9 and 10 indicate paths of carbon particles which are recoiled from the center of the target and enter the base material through the opening of the shielding plate 3. Θ1 and θ2 are the incident angles of the carbon particles incident on the substrate 2. In FIG. 1, the cathode 1 is arranged such that the surface of the target T and the surface of the substrate 2 form an angle of 90 °, in FIG. 2 they form an angle of 45 °, and in FIG. 3 they become parallel. Have been. 1 to 3, the same components are denoted by the same reference numerals.
[0014]
In the example of FIG. 1, for example, if the vertical distance h from the center of the target T to the substrate 2 is 100 mm and the horizontal distance L from the surface of the target T to the center of the opening of the shielding plate 3 is 155 mm, such shielding By providing the plate 3, the incident angles θ1 and θ2 of the carbon particles become 60 ° and 65 °, respectively. A cathode 1 to which a target T is fixed is attached above the vacuum chamber 6, and the substrate 2 is placed on a substrate tray 4 provided at an angle of 90 ° with the target T in the vacuum chamber 6. In this way, the carbon particles from the target T are incident on the base material through the openings 9 and 10 having predetermined angles (θ1, θ2) through the openings of the shielding plate 3 to form a film. Has become. The substrate tray 4 is placed on a rail 5, and is configured to be able to transport the substrate tray 4 and the substrate 2 at a constant speed in the A direction or the B direction while sputtering. For this reason, oblique incidence film formation with good uniformity can be performed on the entire surface of the base material 2, and a carbon thin film having columnar structure carbon in which the pretilt angle or the inclination angle is controlled to a predetermined value in the tissue, that is, a desired carbon thin film in the tissue A carbon thin film containing carbon having a columnar structure having a pretilt angle or an inclination angle can be formed.
[0015]
Similarly, in the examples shown in FIGS. 2 and 3, by appropriately combining the vertical distance h, the distance L, the opening width of the shielding plate, and the like, the oblique incident light having good uniformity over the entire surface of the substrate 2 at an arbitrary incident angle. The membrane can be made. Conversely, for example, in FIG. 3, when the opening position of the shielding plate 3 is provided immediately below the evaporation source, the incident angles θ1 ′ and θ2 ′ become 0 to 10 °, but in this case, it becomes the same as ordinary sputtering. In addition, the film structure does not become columnar. In addition, in FIG. 1, when the incident angles θ1 and θ2 of the particles are limited to angles larger than 80 °, the distance L to the center of the opening of the shielding plate 3 is 200 mm or more. Does not enter. The dynamic film formation rate at this time is extremely low, 100 nm · mm / min, and is not suitable for practical use. Further, the film itself was thin, and a columnar structure could not be confirmed in an electron micrograph of the cross section. By avoiding these situations and setting an opening position that gives an appropriate incident angle, a film having a columnar structure can be obtained.
[0016]
FIG. 4 shows a growth model of a columnar structure of carbon during film formation on the base material 2 performed by using the film formation apparatus. As shown in FIG. 4, since there is the carbon island structure 11 previously deposited on the base material, the carbon particles 12 obliquely incident at a predetermined incident angle θi are more likely to be deposited on a portion corresponding to the shadow of the particles 11. , The probability of deposition on the particles 11 increases. By repeating this deposition, carbon having a columnar structure with gaps like 13 and 14 grows. At this time, generally, as the incident angle θi of the carbon particles increases, the pretilt angle θp of the carbon having the columnar structure tends to decrease. In this regard, the incident angle is variously changed (θi = 10 to 80 °), and the incident angle (θi) and the pretilt angle, which is the inclination angle of the columnar structure, when the carbon thin film is formed as described in Examples described below. FIG. 5 shows the relationship with (θp).
[0017]
Next, FIG. 6 shows a model of a cross section of a carbon film formed when a film forming process similar to the above is performed using a film forming apparatus having the same configuration as the above film forming apparatus except that the shielding plate is not provided. . As shown in FIG. 6, the incident angles θ1 and θ2 of the carbon particles greatly differ depending on the positions on the base material, for example, x1 and x2, and it is difficult to make the pretilt angle θp uniform. In addition, when forming a film while transporting the base material, the controllability of the pretilt angle θp deteriorates.
Therefore, as is clear from FIGS. 4 and 6, a shielding plate is provided on the path of the carbon particles which are rebounded from the center of the target and enter the substrate, and a predetermined opening width is provided at an appropriate position of the shielding plate. By disposing the openings, it is possible to form a carbon thin film containing columnar carbon having an arbitrarily controlled pretilt angle θp with good uniformity.
[0018]
The carbon thin film obtained by the present invention can be used, for example, in a liquid crystal display device as an alignment film for giving a uniform molecular alignment state to a liquid crystal filled between glass substrates provided opposite to each other, It is useful as an electron emission electrode film of a type display device. For example, in a liquid crystal cell using this carbon thin film, a first alignment film made of a thin film containing carbon having a predetermined pretilt angle is applied to a first substrate, and a second alignment film is applied to a second substrate. It can be manufactured by providing a liquid crystal layer between the first alignment film and the second alignment film.
[0019]
【Example】
Hereinafter, as an example of the present invention, an example in which a carbon thin film is formed under the conditions shown in Table 1 using the film forming apparatus shown in FIG. 1 will be described.
The evacuation device 7 is operated to evacuate the vacuum chamber 6 to a predetermined pressure, and output from the cathode power supply 8 to the cathode 1 at a predetermined current density, so that a predetermined flow rate of argon gas and hydrogen gas is supplied into the vacuum chamber. The substrate 2 placed on the substrate tray 4 is transported in the A or B direction on the substrate transport rail 5 at a predetermined transport speed, and sputtering is performed to form a carbon thin film. . The vertical distance h from the center of the target T to the substrate 2 was 100 mm, and the horizontal distance L from the surface of the target T to the center of the opening of the shielding plate 3 was 155 mm. The incident angles θ1 and θ2 of the carbon particles during the film forming process were 60 ° and 65 °, respectively.
[0020]
Electron microscopic observation of the cross section confirmed that the carbon thin film obtained by the above film formation process contained carbon having a columnar structure having a predetermined pretilt angle in the structure.
[0021]
(Table 1)

[0022]
FIG. 7 shows the field electron emission characteristics of the carbon thin film obtained by the above film forming process. In the figure, a curve a indicates the characteristic of the carbon thin film obtained by the above-described film forming process, and a curve b indicates the characteristic of the vertically aligned CNT film obtained by the conventional thermal CVD method. From these curves, it can be seen that the carbon thin film obtained by using the method of the present invention is superior to the conventional case in the field electron emission characteristics.
[0023]
【The invention's effect】
According to the method for forming a carbon thin film of the present invention, carbon atoms and carbon ions are incident on the substrate surface in a predetermined incident angle range, a film is formed, and a thin film containing columnar carbon is formed in the tissue. A carbon thin film containing carbon having a columnar structure in which the pretilt angle or the tilt angle is controlled to a predetermined value can be formed. By a simple transfer film formation, a carbon thin film having a columnar microstructure with good uniformity in both the pretilt angle and the tilt direction can be formed on a large-area substrate.
Further, according to the carbon thin film of the present invention, since carbon having a columnar structure having a pretilt angle or a tilt angle controlled to a predetermined value is contained in the tissue, for example, the characteristic as an alignment film of a liquid crystal display device is obtained. Also, it has excellent field emission characteristics as a field emission electrode film of a field emission display device.
The effect of the carbon thin film forming method of the present invention will be described in more detail below.
(1) Since an alignment film of a liquid crystal display device can be formed without using a rubbing method, problems such as dust adhesion to pixels and maintenance of a rubbing cloth can be solved.
(2) In forming the alignment film of the liquid crystal display device, the film formation and the imparting of the orientation can be performed at the same time, so that the manufacturing process of the alignment film is shortened.
(3) A simpler process for forming a carbon thin film containing columnar carbon such as an alignment film of a liquid crystal display device and a field emission electrode film of a field emission display device is simpler than conventional oblique deposition. A large-area carbon thin film containing carbon having a columnar structure having a pretilt angle or a tilt angle with good uniformity can be manufactured.
(4) When forming a field electron emission electrode film, a process capable of forming an electrode film can be realized irrespective of the type of base material, as compared with the case of manufacturing conventional vertically aligned CNTs. Further, the field electron emission characteristics of the film can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a schematic configuration of a film forming apparatus for performing a carbon thin film forming method according to the present invention.
FIG. 2 is a cross-sectional view showing a schematic configuration of another film forming apparatus for performing the carbon thin film forming method according to the present invention.
FIG. 3 is a sectional view showing a schematic configuration of still another film forming apparatus for performing a carbon thin film forming method according to the present invention.
FIG. 4 is a schematic diagram for explaining a growth model of a columnar structure of carbon during film formation on a substrate by the method for forming a carbon thin film according to the present invention.
FIG. 5 is a graph showing a relationship between an incident angle (θi) and a pretilt angle (θp) in the method for forming a carbon thin film according to the present invention.
FIG. 6 is a cross-sectional view showing a model of a cross-section of a carbon thin film formed by the method of forming a carbon thin film according to the present invention (using an apparatus without a shielding plate).
FIG. 7 is a graph showing field electron emission characteristics of a carbon thin film obtained by the carbon thin film forming method according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Magnetron sputter cathode 2 Substrate 3 Shielding plate 4 Substrate tray 5 Rail of substrate transport mechanism 6 Vacuum tank 7 Exhaust device 8 Power supply for cathode 9, 10 Path of incident carbon particle 11, 12 Carbon particle 13, 14 Columnar structure T Target h Vertical distance from target center to substrate L Horizontal distance from target surface to center of opening θ1, θ2, θi Incident angle of carbon particles θp Pretilt angle

Claims (12)

In a method of forming a carbon thin film on a substrate surface, a carbon atom and a carbon ion obtained from an evaporation source of carbon atoms and carbon ions are incident on the substrate surface at a predetermined incident angle to form a film, and a pretilt is formed. A method for forming a carbon thin film, comprising forming a carbon thin film having a columnar structure of carbon having a controlled angle or inclination angle at a predetermined value in a tissue. 2. The method according to claim 1, wherein the carbon thin film is a thin film used as a liquid crystal alignment film or a field electron emission electrode film. The method for forming a carbon thin film according to claim 1, wherein the incident angle is 10 to 80 °. The method for forming a carbon thin film according to any one of claims 1 to 3, wherein the pretilt angle or the inclination angle is 5 to 90 °. The method according to claim 1, wherein the carbon atom and the carbon ion are obtained from an evaporation source arranged at a predetermined angle with respect to the substrate surface. A method for forming a carbon thin film. Carbon atoms and carbon ions generated from the evaporation source are incident on the surface of the substrate at a predetermined inclination angle through an opening of a shielding plate disposed between the surface of the substrate and the evaporation source in parallel with the surface of the substrate. The method for forming a carbon thin film according to any one of claims 1 to 5, wherein The method for forming a carbon thin film according to any one of claims 1 to 6, wherein the film is formed while moving the substrate linearly during the film formation. The method according to claim 1, wherein the evaporation source is a solid evaporation source. The carbon thin film according to any one of claims 1 to 8, wherein an evaporation source whose evaporation surface is arranged to have an inclination angle of 10 to 80 ° with respect to the substrate surface is used as the evaporation source. Formation method. A carbon atom and a carbon ion obtained from a carbon atom and a carbon ion evaporation source are incident on a substrate surface at a predetermined incident angle to form a film, and have a pretilt angle or a tilt angle controlled to a predetermined value. Carbon thin film containing columnar carbon in its structure. The carbon thin film according to claim 10, wherein the carbon thin film is a thin film used as a liquid crystal alignment film or a field electron emission electrode film. The carbon thin film according to claim 10, which is obtained by the method according to claim 3.

Images