JPH08269709A - Formation of thin film - Google Patents

Abstract

PURPOSE: To obtain a good plating with a convenient device by interposing an insulating dielectric between a cathode and an anode, producing unbalanced low-temp. plasma between the cathode and dielectric under atmospheric pressure to sputter the cathode and forming a thin film on a substrate. CONSTITUTION: An insulating dielectric 3 is interposed between a cathode 1 (of Pt, Au, etc.) and an anode 2 (of Cu, Al, etc.). Gaseous He is introduced between the dielectric 3 and cathode 2, and unbalanced low-temp. plasma 4 is produced under atmospheric pressure by a high-frequency power source. The cathode 1 is sputtered by the plasma 4, and a coating film is formed on a substrate 5 (single-crystal silicon, etc.) set close to the unbalanced low-temp. plasma region. A good-crystallinity coating film is formed in this way.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a thin film of metal or the like on a substrate by performing sputtering with non-equilibrium low temperature plasma under atmospheric pressure.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
Typical methods of forming a metal thin film on a substrate include wet plating methods such as electroplating and electroless plating, vacuum deposition, sputtering, ion plating, dry (vapor phase) plating methods such as MOCVD, and plasma spraying methods. It can be mentioned as a thing.

However, the wet plating method has limitations on the metals that can be plated, and requires the treatment of waste water accompanying the plating operation. The dry plating method generally requires a vacuum and large-scale equipment, and the plasma spraying method uses arc discharge, which has a problem that it is difficult to form a dense film. Therefore, a new surface treatment method that solves such a problem has been desired.

[0004]

Means and Actions for Solving the Problems The inventors of the present invention have conducted diligent studies in order to meet the above demand, and as a result, under atmospheric pressure,
They have found a method that enables good plating with a simple device.

That is, according to the present invention, an insulating dielectric is interposed between the cathode and the anode, a non-equilibrium low temperature plasma is generated between the dielectric and the cathode under atmospheric pressure, and the cathode sputtered from the cathode is generated. Provided is a thin film forming method, which comprises depositing a forming material in a film form on a substrate placed in or near a non-equilibrium low temperature plasma region.

According to the thin film forming method of the present invention, since a thin film of metal or the like is deposited on a substrate under atmospheric pressure, a large-scale device or complicated peripheral equipment is not required, and the deposition rate is high, which is extremely high. It has an excellent feature of having productivity and can continuously process substrates. In addition, since it can be deposited at a relatively low temperature, a wide variety of substrates can be selected, and various types of substrates such as abrasion resistance, scratch resistance, corrosion resistance, heat resistance, conductivity, and decorativeness can be selected. Functions can be added. In particular, the thin film according to the present invention is homogeneous and of high purity, and it is possible to produce a high-quality thin film with few pinholes, cracks, and residual pores.

The present invention will be described in more detail below. In the thin film forming method of the present invention, an insulating dielectric 3 is interposed between a cathode 1 and an anode 2 as shown in FIGS. A non-equilibrium low temperature plasma 4 is generated between the body 3 and the cathode 1 under atmospheric pressure, and a cathode forming material is sputtered from the cathode 1, and the sputtered cathode forming material is placed in a non-equilibrium low temperature plasma region or Substrate 5 placed close to the equilibrium low temperature plasma region
It is deposited on the top in the form of a film. In the figure, 6 is a spacer, 7 is a high frequency power source, and 8 is a gas inlet.

Here, as the cathode, a thin film forming material to be deposited and deposited on the substrate by sputtering, in particular, a metal material is used. For example, Al, Ti, B, Ba, Bi,
C, Cd, In, Mn, Nb, Cr, Fe, Co, N
i, Cu, Si, Sn, Zn, Mo, Ag, W, Pt,
Au, Pb, Ta, Te and their alloys (especially Cu-
The same cathode materials as those conventionally used for sputtering under vacuum, such as Zn, Cu-Al, Co-Cn, etc., can be used.

Further, as the anode material, Cu, A
1, stainless steel, steel, brass, etc. are used.

The insulating dielectric has a function of stably generating and maintaining non-equilibrium low temperature plasma under atmospheric pressure.
_{Al 2 O 3, YSZ, SrTiO} 3, PbTiO 3 -PbZ
Although it can be formed of nO or the like, Al ₂ O ₃ is generally used.

The substrate material is not particularly limited, metals such as single crystal silicon, quartz, glass, aluminum, steel and stainless steel, ceramics such as silicon nitride, alumina and boron nitride, polyethylene, polypropylene,
Examples thereof include polyesters, polyamides, polyimides, epoxy resins, phenol resins, polyurethanes, fluororesins, organic resins such as organic silicone resins, artificial teeth (natural apatite), and the like.

When non-equilibrium low temperature plasma is generated according to the present invention, an AC power source is used as a power source. In this case, the frequency can be 1 kHz to 10 ⁸ Hz,
For example, the one of 13.56 MHz which is often used industrially can be used.

A rare gas such as He or Ar is preferably used as the gas, and it is particularly effective to use He as the main gas. The main gas is ventilated in the apparatus and an AC power source (high frequency transmission) is used. Machine) can be energized to generate plasma.

In this case, the film forming rate can be improved by further mixing Ar gas with He gas. The supply amount of this Ar gas is 10 times that of the main He gas.
From the viewpoint of film formation rate and deposited film characteristics, it is preferable that the amount is 1000 parts by volume or less, especially 100 parts by volume or less, relative to 0 parts by volume.

Further, by mixing H ₂ gas, the oxidation of the deposited film can be suppressed. In this case, the amount of H ₂ gas mixed is preferably 50 parts by volume or less with respect to 100 parts by volume of the main He gas. On the contrary, oxygen gas,
If nitrogen gas or the like is mixed, an oxide film, a nitride film or the like can be formed.

The gas flow rate is selected according to the size of the apparatus, the required film quality, etc. and is not particularly limited. For example,
50 to 1000 sccm, preferably 100 to 600 s
Although it can be set to ccm, the flow rate also changes due to expansion and contraction of the apparatus, and is not limited to this.

In the present invention, the non-equilibrium low temperature plasma is formed at atmospheric pressure (760 Torr), and the thin film is formed under this atmospheric pressure. In this case, when the substrate on which the thin film is formed has a low melting point and a low decomposition point, the thin film can be formed while cooling the substrate if necessary.

The plasma generator used in the present invention is as shown in FIGS. 1 and 2, and FIG. 2 is capable of generating plasma in the form of a sheet. As such a plasma generator, Specifically, Japanese Patent Laid-Open No. 4-2122
No. 53, No. 4-242924, and Appl. Phy
s. Lett. , 60 (7), 17, Feb. , 199
2 and the like can be used.

In this case, the substrate is placed in the non-equilibrium low-temperature plasma region or at a position close to the non-equilibrium low-temperature plasma region, and the substrate or plasma generator may be scanned to form a film in a linear shape, a band shape, or the like. it can. Further, since the cathode is removed as the film formation progresses, it is possible to mechanically supply the cathode in accordance with this.

[0020]

According to the present invention, it is possible to form a homogeneous, high-purity, and dense thin film without pinholes, cracks, and pores at a high film-forming rate under atmospheric pressure. It is effectively used for materials and medical applications such as dentistry.

[0021]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Examples 1 to 3] Using a device as shown in FIG. 1, Pt, Pd, and Au were used as cathodes on a silicon (100) substrate under the following conditions under atmospheric pressure (760 Torr) to produce these metals. A thin film of Here, an Al ₂ O ₃ pipe having a diameter of 20 mm was used as the insulating dielectric. The results of the film formation rate are shown below.

Example 1 2 3 Cathode Material Pt Pd Au Pressure (Torr) 760 760 760 RF Power (W) 140 140 140 140 He Gas (sccm) 300 300 300 Deposition Rate Pt Pd Au Examples 1-3 0.0085 0.075 0.024 Comparative example ^* 0.004 0.057 0.020 * G. Weher et al. , J. et al. Appl. Phys. , 33 , 1842 (1962), which is a reference value obtained by a conventional sputtering method in a vacuum.

From the above results, it is recognized that the atmospheric pressure sputtering method of the present invention has a film formation rate equal to or higher than that of the conventional vacuum sputtering method.

Example 4 Ag was used as the cathode material, an Al ₂ O ₃ pipe (diameter 5 mm) was used as the insulating dielectric, RF power 90 W, He gas 200 sccm, H ₂
At a flow rate of 0 to 7 sccm, the atmospheric pressure (7
Sputtering was performed under 60 Torr) to form an Ag film on a silicon (100) substrate. The X-ray diffraction patterns of the obtained deposited film are shown in FIGS.

From these results, it was found that the addition of H ₂ suppressed the oxidation and obtained a particularly good Ag film.

[Embodiment 5] Pt is used as a cathode material, and an Al ₂ O ₃ pipe (diameter 20 mm) is used as an insulating dielectric.
RF power of 140 W, He gas of 300 sccm,
Sputtering was performed under atmospheric pressure (760 Torr) under conditions of Ar gas flow rate of 0 to 50 sccm to form a Pt film on a silicon (100) substrate. The X-ray diffraction pattern of the obtained deposited film is shown in FIG. Further, FIG. 6 shows the relationship among the Ar gas flow rate, the film formation rate, and the resistivity.

From the results shown in FIG. 5, good Pt with a low degree of oxidation was obtained.
It is recognized that the film is formed and that each Pt film has a strong (111) orientation. Moreover, from the result of FIG.
It was observed that the deposition rate and the resistivity increased as the flow rate of Ar gas increased from 0 to 40 sccm.
It is recognized that the deposition rate and the resistivity can be controlled by controlling the gas flow rate.

[Embodiment 6] RF power of 120 to 140
Example 5 except that the flow rates of W and Ar gas were set to 40 sccm
A Pt film was formed in the same manner as above, and the influence of the RF power on the film formation rate was examined. The result is shown in FIG.
Surface AFM (Atomic Force Micro) when the RF power of 120, 130, 140 W
The result of the observation of (copy) is shown. The magnifications in FIGS. 8 to 10 are as follows.

From the results of FIGS. 7 and 8 to 10, it can be seen that the film formation rate increases with increasing power, but the surface becomes rough. However, a very flat and uniform film was generally obtained, and the average roughness was generally ± 20Å.

[Example 7] A Pd film was formed on a silicon (100) substrate in the same manner as in Example 5 except that Pd was used as the cathode material and the Ar gas flow rate was set to 0 to 10 sccm. FIG. 11 shows the result of the X-ray diffraction pattern, and FIGS. 12 and 13 show the results of the film forming rate and the resistivity by changing the Ar gas flow rate.

From these results, the crystallinity of the deposited Pd film is good, the film forming rate increases as the Ar gas flow rate increases, and the film quality does not deteriorate even if the Ar gas flow rate increases ( The resistivity does not increase).

Example 8 An Au film was formed on a silicon (100) substrate in the same manner as in Example 5 except that Au was used as the cathode material and the Ar gas flow rate was set to 0 to 50 sccm. FIG. 14 shows the results of the X-ray diffraction diagram, and FIG. 15 shows the results of the film forming rate and the resistivity depending on the Ar gas flow rate change.

From these results, it is recognized that the crystallinity of the deposited Au film is good, and that the film formation rate increases and the resistivity decreases as the Ar gas flow rate increases.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of an apparatus used in the present invention.

FIG. 2 is a schematic perspective view showing another example of the apparatus used in the present invention.

FIG. 3 is an X-ray diffraction diagram of the Ag film obtained in the present invention.

FIG. 4 is an X-ray diffraction diagram of the Ag film obtained in the present invention.

FIG. 5 is an X-ray diffraction diagram of the Pt film obtained in the present invention.

FIG. 6 is a graph showing the relationship between Ar gas flow rate, Pt film formation rate, and resistivity.

FIG. 7 is a graph showing the relationship between RF power and Pt film formation rate.

FIG. 8: Surface AF of Pt film formed with RF power of 120 W
It is an M photograph.

FIG. 9: Surface AF of Pt film formed with RF power of 130 W
It is an M photograph.

FIG. 10: Surface A of Pt film formed with RF power of 140 W
It is an FM photograph.

FIG. 11 is an X-ray diffraction pattern of the Pd film obtained in the present invention.

FIG. 12 is a graph showing the relationship between the Ar gas flow rate and the Pd film formation rate.

FIG. 13 is a graph showing the relationship between the Ar gas flow rate and the resistivity of the Pd film.

FIG. 14 is an X-ray diffraction pattern of the Au film obtained in the present invention.

FIG. 15 is a graph showing the relationship between the Ar gas flow rate, the deposition rate of an Au film, and the resistivity.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukihiro Kusano 1-50-15-305 Nishikoigakubo, Kokubunji City, Tokyo (72) Inventor Toshio Naito 969-1 Makinu, Misaki-ku, Kawasaki City, Kanagawa Prefecture

Claims (3)

[Claims] 1. A non-equilibrium low-temperature plasma is generated between the dielectric and the cathode by interposing an insulating dielectric between the cathode and the anode to prevent the cathode forming material sputtered from the cathode from being formed. A method for forming a thin film, comprising depositing a film on a substrate placed in an equilibrium low temperature plasma region or in the vicinity of a non-equilibrium low temperature plasma region. 2. Al, Ti, B, B as a cathode material
a, Bi, C, Cd, In, Mn, Nb, Cr, Fe,
Co, Ni, Cu, Si, Sn, Zn, Mo, Ag,
The method according to claim 1, wherein a metal selected from W, Pt, Au, Pb, Ta, Te and alloys thereof is used. 3. The main gas is He gas, to which A
3. The method according to claim 1, wherein the non-equilibrium low temperature plasma is generated under atmospheric pressure by mixing r gas and / or H ₂ gas.