JPH06330283A - Film forming apparatus and film formation of transparent conductive film - Google Patents

Abstract

PURPOSE:To provide the method for forming an amorphous ITO film by uniformly taking a sufficient amt. of hydrogen into the ITO film in order to form the ITO film and the apparatus for this method. CONSTITUTION:A hydrogen plasma chamber 50 is previously installed between a deposition preventive plate 15 and substrate 16 in a sputtering film forming device 10. While gaseous hydrogen or molecules contg. hydrogen atoms are introduced from a cylinder 22 into this hydrogen plasma chamber 50, an electric discharge is generated by a filament 18 to form plasma and to create the hydrogen in an excited state. The hydrogen in the excited state is introduced near the substrate 16 in the sputtering film forming device 10, the hydrogen is incorporated into the sputtered particles and is deposited on the substrate 16. As a result, the ITO film having a high etching rate is obtd. and the productivity of a liquid crystal display element is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming apparatus for forming a transparent conductive film by a sputtering method, and particularly to a film forming apparatus suitable for forming an amorphous indium tin oxide film. It is about.

[0002]

2. Description of the Related Art A transparent and low-resistance ITO film (indium tin oxide) is used for a transparent electrode used in a liquid crystal display element, and a magnetron sputtering method is often used for forming the film. As for the sputtering method, for example, as described in detail in "Sputtering Phenomenon" by Akira Kanehara (University of Tokyo Press), the ions in the plasma generated in the vacuum chamber are targets that are a mass of material to be formed into a film. It is a film-forming method in which the target is scattered and the target is scattered at the atomic level. The magnetron sputtering method is a film-forming method that applies the sputtering method, and is a device that generates a high-density plasma in the vicinity of the target by a magnetic field. The film-forming rate is higher than that of a normal sputtering method that does not use magnetic field generation means. There is.

Since the resistance value and the light transmittance of the ITO film greatly change due to a slight difference in composition between indium and tin and oxygen, it is necessary to form the film by accurately adjusting the composition ratio thereof. . In the film formation of ITO by the sputtering method, a sintered body in which indium oxide and tin oxide are mixed is often used as a target, and an inert gas is often used as the sputtering gas. However, when the sputtering gas is only the inert gas,
The obtained ITO film lacks oxygen, and a film having low resistance and high transmittance cannot be obtained. Therefore, a small amount of additional gas such as oxygen is added to the sputtering gas to react the film with oxygen during film formation to adjust the composition of the ITO film. Thereby, the ITO having a predetermined resistance value and transmittance is obtained.
A film is obtained.

Further, when the ITO film is used as a pixel electrode of a liquid crystal display element, it is necessary to pattern the ITO film in each pixel, and therefore, low resistance and high transmittance as well as easy etching are required. To be done. From the viewpoint of productivity of the liquid crystal display element, it is desirable that the etching rate be high. ITO
It is known that the etching rate of a film is related to the crystallinity of the film, and that an amorphous film has a higher etching rate.

Therefore, it has been proposed to obtain an amorphous ITO film by forming a film while keeping the substrate at a low temperature. However, when the substrate is kept at a low temperature, the ITO film becomes amorphous, but there is a problem that the resistance increases and the transmittance decreases.

Further, it has been proposed that an amorphous ITO film is formed by incorporating impurities into the film without impairing the resistivity and transmittance of the film. For example, a method of mixing hydrogen into a sputtering gas is disclosed in Japanese Patent Laid-Open No. 3-644.
No. 50. In this method, a part of hydrogen gas becomes hydrogen atoms by plasma, and the hydrogen atoms are mixed into the ITO film to form an amorphous film. Further, it is disclosed in JP-A-2-163363 that water is added to the sputtering gas. In this method, water molecules are decomposed into oxygen atoms and hydrogen atoms by plasma and taken into the film to form an amorphous film.

Further, in JP-A-1-177360,
There has been proposed a method of lowering the resistance and increasing the efficiency of the ITO film by irradiating the ITO film with excited hydrogen particles for post-treatment.

On the other hand, JP-A-3-183760 also discloses a method of activating oxygen gas to form an ITO film introduced near the substrate.

[0009]

However, in the above-mentioned conventional technique, the method proposed in Japanese Patent Laid-Open No. 3-64450 obtains hydrogen atoms by exciting hydrogen gas with plasma. Due to its small size, it is less likely to collide with ions in plasma, and only a part of hydrogen molecules become hydrogen atoms. Therefore, it is necessary to increase the partial pressure of hydrogen gas in the sputtering gas in order to obtain the hydrogen atoms necessary for sufficiently amorphizing the ITO film. Sputtering rate decreases. Therefore, there is a problem that an amorphous ITO film cannot be efficiently obtained.

Further, the method described in JP-A-2-163363 for obtaining hydrogen atoms and oxygen atoms by exciting water molecules with plasma is to obtain hydrogen atoms efficiently because the size of water molecules is large. However, it is necessary to introduce water vapor into the sputtering apparatus. Since the water vapor adheres to the inner wall of the vacuum container of the sputtering apparatus as water, it is very difficult to control the amount of water vapor in the vacuum container. Therefore, it is difficult to control the amount of hydrogen atoms taken into the ITO film, and it is difficult to stably produce an ITO film having a constant film quality.

Further, as described in JP-A-1-177360, the method of post-treating an ITO film with excited hydrogen particles is to make hydrogen particles collide with a polycrystalline ITO film. Although it is possible to change the low efficiency and the transparency, it is not possible to form an amorphous film.

Further, the method of activating oxygen gas in JP-A-3-183760 to guide it to the vicinity of the substrate tends to form a polycrystalline film rather than an amorphous film, and cannot increase the etching rate.

It is an object of the present invention to provide a method for forming a film by uniformly incorporating a sufficient amount of hydrogen into an ITO film to form an amorphous ITO film, and an apparatus therefor.

[0014]

The inventors of the present invention can effectively incorporate hydrogen into an ITO film if hydrogen is activated during film formation, and as a result, a non-etching material having a high etching rate is used. It was found that a crystalline ITO film can be obtained. Here, the activated hydrogen is a hydrogen atom in an excited state. Therefore, the above object is achieved by treating the introduced hydrogen gas or molecules containing at least hydrogen atoms with plasma to generate excited hydrogen atoms and mixing them into the ITO film.

Therefore, in order to achieve the above object, according to the present invention, a target containing at least oxygen, indium and tin is sputtered in a film formation space in which a substrate is arranged to scatter sputtered particles, In a space different from the film formation space, a molecule containing a hydrogen atom is excited to generate an excited state hydrogen atom, the generated excited hydrogen atom is guided to the film formation space, and the sputtered particles and excited state hydrogen are generated. There is provided a method for forming a transparent conductive film, which comprises mixing atoms and depositing them on the substrate.

In order to achieve the above object, according to the present invention, a film forming chamber for forming a film forming space, a substrate holder and a target holder arranged to face the film forming space, In a sputtering apparatus having a sputtering gas introduction unit for introducing a sputtering gas into a film chamber, an atom is generated which excites a molecule containing a specific atom to generate a specific atom in an excited state and release the atom into the film formation space. A sputtering apparatus is provided, which is provided with a means and a source gas introducing means for introducing a source gas containing at least a part of a gas of a molecule containing a specific atom into the atom generating means.

[0017]

First, as in the case of forming a polycrystalline ITO film by a sputtering method, a target containing at least oxygen, indium and tin is sputtered in the film forming space where the substrate is arranged to scatter sputtered particles. Let Separately, a molecule containing hydrogen atoms is excited in a space different from the film formation space to generate excited hydrogen atoms.

Next, the excited hydrogen atoms are introduced into the film formation space, the sputtered particles and the excited hydrogen atoms are mixed and deposited on the substrate.

In the method of the present invention, since hydrogen atoms in the excited state are generated in a space different from the film formation space, an amorphous ITO film can be formed regardless of the plasma in the film formation chamber. It is possible to generate a necessary and sufficient amount of excited state hydrogen atoms. Further, when the excited hydrogen atoms are mixed with and brought into contact with the sputtered particles, the excited hydrogen atoms activate the sputtered particles, so that the sputtered particles are deposited on the substrate in a state of incorporating the hydrogen atoms. As a result, a sufficient amount of hydrogen can be incorporated into the film on the substrate. for that reason,
An amorphous ITO film having a high etching rate can be formed with good reproducibility.

[0020]

An embodiment of the present invention will be described with reference to the drawings.

First, a sputtering apparatus which is an embodiment of the present invention will be described with reference to FIG.

The sputtering apparatus according to the first embodiment of the present invention is
The film forming chamber 10 and the hydrogen plasma chamber 50 provided in a part of the film forming chamber 10 are provided. The hydrogen plasma chamber 50 is provided with an opening 50a, and the opening 50a
Thus, the space of the film forming chamber 10 and the space of the hydrogen plasma chamber 50 communicate with each other.

The hydrogen plasma chamber 50 includes a film forming chamber and a film forming chamber 1.
0 is an indium tin oxide (ITO) target 11
Target holder 11a for holding the substrate 16 and
And a substrate holder 17 having a mechanism for transporting. Target holder 11a and substrate holder 17
Holds the target 11 and the substrate 16 at positions facing each other. Between the target 11 and the substrate 16,
An anti-adhesion plate 15 is placed on a portion other than the substrate 16 to prevent an excessive film from adhering thereto.

A power supply 14 for applying a voltage to the target 11 is connected to the target holder 11a, and a magnetron magnetic field generating magnet 12 and a yoke 13 forming a magnetic circuit are provided on the back surface of the target holder 11a.
And are arranged.

Further, the film forming chamber 10 is connected to an exhaust device 25 for maintaining a vacuum, a cylinder 24 for supplying a sputtering gas into the film forming chamber 10 and a mass flow controller 23.

The hydrogen plasma chamber 50 is installed closer to the substrate holder than the deposition preventive plate 15. The opening 50 a of the hydrogen plasma chamber 50 is located near the substrate 16. The hydrogen plasma chamber 50 supplies a large amount of activated hydrogen atoms (that is, excited hydrogen atoms) onto the substrate 16. A gas cylinder 22 for supplying a raw material gas and a mass flow controller 21 are connected to the hydrogen plasma chamber 50. A filament 18 is installed in the hydrogen plasma chamber 50. The filament 18 has
A power supply 19 for supplying a current and a power supply 20 for applying a constant voltage to the filament 18 are connected.

Next, a procedure for forming an amorphous ITO film with the sputtering apparatus shown in FIG. 1 will be described.

First, in the hydrogen plasma chamber 50, the hydrogen partial pressure 3
% Of argon and hydrogen mixed raw material gas from an external gas cylinder 22 via the mass flow controller 21
Introduce 10 CCM. A current is supplied to the filament 18 from a power source 19 to heat the filament 18, and a negative voltage is applied from the power source 20 to generate plasma in the hydrogen plasma chamber 50. Hydrogen gas is excited in plasma to generate excited hydrogen atoms. Excited hydrogen atoms are generated in the hydrogen plasma chamber 5 by the pressure difference between the hydrogen plasma chamber 50 and the film forming chamber 10.
It is drawn into the film chamber 10 through the opening 50a of 0.

On the other hand, 100 CCM of a mixed sputtering gas of argon and oxygen having an oxygen partial pressure of 1% is supplied to the film forming chamber 10 as a sputtering gas, and the gas pressure of the film forming chamber is 4 × 10 ³ T.
Keep at orr. Then, a power of 200 W is applied to the target from the DC power source 14 to generate oxygen and argon plasma in the film forming chamber 10. Argon ions in the plasma collide with the target 11 and scatter sputtered particles. The scattered sputtered particles reach the substrate 16, but are mixed with excited hydrogen atoms extracted from the hydrogen plasma chamber 50 in the vicinity of the substrate 16. Further, the sputtered particles also mix with oxygen atoms in the film formation chamber.

When hydrogen atoms in an excited state are mixed with and brought into contact with the sputtered particles, the hydrogen atoms activate the sputtered particles, so that the sputtered particles are deposited on the substrate 16 with the hydrogen atoms taken in. Thereby, the ITO on the substrate 16
The membrane can be loaded with a sufficient amount of hydrogen. At this time, oxygen atoms in the film forming chamber are also taken into the ITO film, and the oxygen concentration in the ITO film is increased. When hydrogen atoms are taken into the ITO film, the hydrogen atoms become impurities and hinder the crystallization of the ITO film, so that the ITO film is made amorphous and an amorphous ITO film is formed.

In order to make the ITO film sufficiently amorphous, it is necessary to take in a sufficient amount of hydrogen atoms. In this embodiment, since hydrogen atoms in an excited state are separately generated in the hydrogen plasma chamber 50, the plasma of the sputtering gas in the film forming chamber chamber 10 is not affected, and the sputtering rate is not lowered. A quantity of excited state hydrogen atoms can be obtained. Therefore, with the sputtering apparatus of this embodiment, a sufficiently amorphous ITO film can be obtained.

When the characteristics of the ITO film obtained by the above method were evaluated, an ITO film having a resistivity of 1 × 10 ³ Ωcm and a transmittance of 90% or more was obtained.

The etching rate of the ITO film can be determined by the crystallinity of the film. If the crystallinity is high, the etching rate is low. On the other hand, a film having low crystallinity, that is, an amorphous film has a high etching rate. Therefore, the film was subjected to X-ray diffraction analysis, and the crystallinity was evaluated by the X-ray diffraction intensity measured at that time. FIG. 5 shows the X-ray diffraction intensity of the above-mentioned ITO film produced by supplying hydrogen in an excited state from the hydrogen plasma chamber 50. Further, as a comparative example, FIG. 6 shows the X-ray diffraction intensity of an ITO film produced without supplying excited hydrogen. It can be seen that the X-ray diffraction intensity peak in the case of supplying hydrogen in the excited state of this example is reduced to about 1/2 of the intensity peak of the comparative example. This shows that an amorphous film, that is, an ITO film having a high etching rate is obtained.

Next, an ITO film produced by changing the flow rate of the raw material gas introduced into the hydrogen plasma chamber 50 in this embodiment,
The relationship with the etching rate of the film was measured. The result is shown in FIG. 7. It can be seen from FIG. 7 that the etching rate of the ITO film depends on the amount of raw material gas, that is, the amount of hydrogen gas, and the etching rate increases as the amount of hydrogen gas increases. Therefore, the etching rate of the ITO film can be controlled by controlling the supply amount of hydrogen gas in the film forming method of this embodiment. By increasing the amount of the source gas in this embodiment, the formed ITO film can be etched in a short time. Therefore, when a liquid crystal display element is manufactured using this ITO film, the productivity can be improved.

In the above embodiment, the hydrogen plasma 5 is used.
The amount of excited hydrogen atoms generated at 0 can be easily controlled in the plasma of the film forming chamber 10 by the amount of source gas supplied to the hydrogen plasma chamber 50 and the voltage and current applied to the filament 18. Therefore, the film formation rate in the film formation chamber 10 and the amount of hydrogen atoms can be controlled independently of each other, so that the film formation rate does not decrease and
By supplying and mixing the required amount of hydrogen atoms,
An ITO film incorporating an arbitrary amount of hydrogen atoms can be obtained. Therefore, the crystallinity of the ITO film can be adjusted arbitrarily,
An amorphous ITO film having a required etching rate, resistance, and transparency can be stably formed.

Further, in the first embodiment, the filament 1
8 was used to generate plasma, but the method is not limited to this, and a method of using high frequency (RF) as shown in FIGS. 2 and 3 or a method shown in FIG. 4 as means for activating hydrogen. Microwaves can also be used.

In the embodiment of the sputtering apparatus shown in FIG. 2, a coil 26 is arranged on the outer periphery of the hydrogen plasma chamber, and the coil 26 has an R shape.
The F power source 27 is connected. The other structure is similar to that of FIG. In the case of this embodiment, since no electrode is required in the hydrogen plasma chamber 50, there is no problem of electrode wear and the hydrogen plasma chamber can be continuously used for a long period of time.

In the embodiment shown in FIG. 3, an electrode 28 is provided outside the hydrogen plasma chamber 50, an RF power source 27 is connected to the electrode 28, and a high frequency is applied. This embodiment also has a problem of electrode wear. Absent. FIG. 4 shows a case where a microwave is used for plasma generation and the coil 3 around the hydrogen plasma chamber 50 is
0 is arranged and plasma is generated by sending microwaves from the microwave power supply 29 into the magnetic field generated in the coil 30. Also in the embodiments of FIGS. 2 to 4, the same effect as that of the embodiment of FIG. 1 is obtained.

When forming an ITO film on a large-area substrate, it is necessary to uniformly distribute the excited hydrogen on the substrate 16. However, since excited state hydrogen loses energy in a short time, it is difficult to supply excited state hydrogen from one hydrogen plasma chamber over a large area. In such a case, activated hydrogen can be supplied with good uniformity by using a plurality of mechanisms for exciting hydrogen. Further, when a substrate transfer type film forming apparatus is used, if a plurality of hydrogen activation mechanisms are provided in a direction substantially perpendicular to the transfer direction, the IT will be sufficiently uniform.
Hydrogen can be incorporated into the O film.

[0040]

As described above, according to the present invention, a hydrogen atom in an excited state is generated in a space different from the plasma of the film forming chamber, so that the film forming rate is not affected and the hydrogen atom is sufficiently generated. An amorphous ITO film containing a large amount of hydrogen can be stably formed.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a sputtering apparatus having a hydrogen plasma chamber 50 that uses a filament 18 to generate plasma according to an embodiment of the present invention.

FIG. 2 is a hydrogen plasma chamber 5 for generating plasma using an RF power supply 27 and a coil 26 according to another embodiment of the present invention.
The block diagram which shows the structure of the sputtering apparatus which has 0.

FIG. 3 shows an RF power source 27 and electrodes 2 according to another embodiment of the present invention.
Hydrogen plasma chamber 50 for generating plasma using
Block diagram showing the configuration of a sputtering apparatus having a.

FIG. 4 is a block diagram showing an individual sputtering apparatus having a hydrogen plasma chamber 50 for generating plasma using microwaves according to another embodiment of the present invention.

FIG. 5 is a graph showing an X-ray diffraction intensity of an ITO film formed by using excited hydrogen atoms in an example of the present invention.

FIG. 6 is a graph showing an X-ray diffraction intensity of an ITO film formed without using excited hydrogen atoms as a comparative example.

FIG. 7 is a graph showing the relationship between the amount of introduced source gas and the etching rate of the ITO film in the ITO film obtained in this example.

[Explanation of symbols]

11 ... ITO target, 16 ... Substrate, 18 ... Filament, 19 ... Filament heating power supply, 20 ... Hydrogen plasma generation power supply, 21 ... Mass flow controller, 22
… Hydrogen gas cylinder, 50… Hydrogen plasma chamber.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuhiro Kamei 1-1-1, Kokubun-cho, Hitachi-shi, Ibaraki Hitachi Co., Ltd. Kokubun factory (72) Inventor Satoshi Umehara 1-1-1, Kokubun-cho, Hitachi-shi, Ibaraki No. 1 Stock company Hitachi Kokubu factory

Claims (6)

[Claims] 1. A film forming space in which a substrate is disposed, a target containing at least oxygen, indium and tin is sputtered to scatter sputtered particles, and a molecule containing hydrogen atoms is provided in a space different from the film forming space. To generate excited hydrogen atoms, guide the generated excited hydrogen atoms to the film formation space, and mix the sputtered particles and excited hydrogen atoms to deposit them on the substrate. A characteristic method of forming a transparent conductive film. 2. The transparent conductive film according to claim 1, wherein excited hydrogen atoms are generated by generating plasma of molecules containing hydrogen atoms in a space different from the film formation space. Membrane method. 3. The method for forming a transparent conductive film according to claim 1, wherein the sputtered particles and excited hydrogen atoms are mixed in the vicinity of the substrate. 4. A film forming chamber for forming a film forming space, a substrate holder and a target holder arranged to face the film forming space, and a sputtering gas introducing means for introducing a sputtering gas into the film forming chamber. In a sputtering device having: an atom generating unit that excites a molecule containing a specific atom to generate a specific atom in an excited state and release the atom into the film formation space; and a gas of a molecule containing the specific atom. A sputtering apparatus, comprising: a raw material gas introducing means for introducing a raw material gas containing the raw material gas into the atom generating means. 5. The atom generating means according to claim 4,
An atom generation chamber forming a space communicating with the film formation space,
A sputtering apparatus comprising: a plasma generation unit that generates plasma of the source gas in the generation chamber. 6. The sputtering apparatus according to claim 5, wherein the space of the atom generation chamber communicates with a space in the film formation space near the substrate holder.