JPS628408A - Improved sputtering - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to improvements in sputtering methods.

[Prior Art] Reactive sputtering has been widely used as a method for producing transparent conductive oxide films because it is relatively easy to produce transparent conductive films of good quality with good reproducibility. Ta.

However, with conventional methods, it is difficult to target metals, metal alloys, or metal oxides.
In order to obtain a transparent conductive film with low resistance and high transmittance, a high substrate temperature (400° C. or higher) is required.

Furthermore, depending on the material, it is possible to obtain a low-resistance film even on a relatively low-temperature substrate by selecting the starting materials and strictly controlling the deposition conditions, but the film quality is not sufficient. is δ
I couldn't.

The present invention provides an fjiI2. In particular, it is an object of the present invention to provide an improved sputtering method by which transparent conductive oxide films can be obtained. .

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems.1 The present invention forms high-frequency discharge plasma by providing a high-frequency coil between a substrate and a target, This makes sputtering possible even in a pressure range of 2×10=~3×101 Torr.

The sputtered particles are sputtered through it.

In the low-pressure cass battering method in which a film is formed by passing through the high-frequency coil, the high-frequency coil (1) is grounded via a high-frequency choke coil and a DC resistance, and the DC resistance level between the high-frequency coil (L) and the ground is controlled. An improved sputtering method is provided in which the plasma potential of the frequency discharge plasma is maintained at a positive potential relative to ground potential.

[Structure of the Invention] Hereinafter, the present invention will be described in more detail with reference to the drawings.

FIG. 1 shows a schematic diagram of a sputtering apparatus for carrying out the present invention.
t is a vacuum chamber 4 composed of a base 2 and a Pelger 3;
A sputter source 5 is placed in the upper part of the vacuum chamber 4.The sputter source 5 shown in the figure applies a special magnetic field to the target using a magnetron 6, and causes the sputter particles to enter the magnetic field. confine the ionization efficiency to L
This is for magnetrono sputtering in which a high deposition rate can be obtained by increasing the plasma density by increasing the plasma density, but of course the sputtering source is not limited to this, and other types of sputtering sources can be used as well. =i Also, a substrate holder 7 is placed in the upper part of the vacuum chamber 4, and this holder 7 allows a substrate 8 on which a thin film is to be formed to be connected to the sputtering source 5.
is placed opposite to. Furthermore, a high frequency coil 9 is disposed within the vacuum chamber 4 for generating a high frequency external low discharge from the substrate holder between the sputter source 5 and the substrate holder 7 to ionize sputter particles and gas. As this high frequency introduction coil 9, the sputter source 5
passing through almost the center of
Typical coils include one or more turns of aluminum, stainless steel, copper, etc., but coils of various shapes such as ring-shaped coils, donut-shaped coils, or conical coils can also be used.

In the apparatus of configuration 1, a high frequency discharge plasma region is formed near the high frequency coil 9.

The gas and some of the sputtered particles passing through it are ionized and formed as a thin film on the surface of the substrate 8.

Further, in such a sputtering apparatus, a capacitor 11 is connected in series between the high frequency power source IO and the high frequency coil 9, thereby forming a blocking capacitor. A DC resistor 13 is placed between the blocking capacitor 11 and the high frequency coil 9 via a high frequency choke coil 12, and is grounded. The DC resistor 13 may be a variable resistor or a fixed resistor. If this is done, the charge '? due to the difference in the moving speed of the positive ions and the electric current flowing into the high frequency coil 9 will be reduced. s! 1K is relaxed by its resistance. As a result, by changing this resistance, the self-bias of the high frequency coil can be changed. As a result, depending on it, the plasma potential also changes, e.g.

When the resistance is set to O, the self-bias voltage becomes Ov,
Correspondingly, the plasma potential becomes several hundred volts. In this way, it is particularly effective in increasing the plasma potential in the positive direction.

In other words, although the voltage effect near the coil remains the same, the difference between the plasma potential and the target potential is equal to
The energy of the sputtered particles is increased, and a potential drop occurs near the substrate at ground potential, increasing the positive ion acceleration effect. These controls can be performed independently of the plasma density, which improves film formation. It becomes possible to improve quality.

In the present invention, a high frequency is further applied to the substrate side,
It is also possible to control the energy using a so-called high frequency bias method. In this case, it is possible to use two high frequency power supplies, but it is also possible to use one high frequency power supply by dividing it into two circuits.

In forming the film according to the present invention, first, a predetermined substrate 8 selected from various materials such as glass, plastic, ceramic, etc. is set on the substrate holder 8 in the vacuum chamber 4, and the inside of the vacuum chamber 4 is set at 5 XIO6 Tarr. After reducing the pressure, a predetermined amount of sputtering gas such as argon is introduced into the vacuum chamber 4, and if necessary, an active gas such as oxygen is introduced to achieve a predetermined degree of vacuum, for example, about 5X 1O=Torr. adjust.

Next, after performing press sputtering by applying a high frequency voltage or a DC voltage to the target 8, a high frequency voltage is applied to the high frequency coil 9 to generate high frequency plasma,
Accelerate sputtered particles to perform sputtering,
A film is formed on the surface 1- of the substrate 8.

In the present invention, as a sputtering method in which a target material of a sputtering source is sputtered with a high-vacuum knife and sputtered particles are deposited on the adhering surface of a substrate to form a film, a mixed gas for causing an electric discharge is sputtered. When sputtered particles do not react with physical sputtering methods.

A reactive sputtering method (chemical sputtering method) is applied, which causes a chemical reaction between mixed gas and sputtered particles to produce a predetermined oxide, nitride, sulfide, carbide, or other various coatings. In addition, as a method for generating positive ions to knock out target atoms from the surface of the target, an anode and a cathode are placed opposite each other, and a flame such as argon is introduced to separate the anode and cathode. For example, if the target constituting the cathode is conductive, a method can be used in which a DC voltage, AC voltage, or high-frequency voltage is applied between the electrodes to cause a discharge and generate cations. Apply DC voltage, AC voltage or high frequency voltage,
Furthermore, if the target is insulating, a high frequency voltage is applied.

In addition, in the present invention, the pressure in the vacuum chamber during coating formation by sputtering is preferably 2X 1O-3 Torr or less, and it is preferable to form the coating at this vacuum level. Also, in the case of reactive sputtering, the pressure is 2X 1O-3 Torr or less. In the case of the reactive sputtering method, the degree of vacuum is as follows, and the ratio of the reactive gas to the sputtering gas is preferably about 10 to 50%, although it varies depending on the stoichiometry of the target film.2. When the degree of vacuum is OX 1O-3 Torr or less, reaction between the target and the reactive gas can be prevented and the quality of the formed thin film can be improved.

The coating preferably formed and formed according to the present invention is S
Transparent conductive films of metal oxides such as b-doped tin oxide and Sn-doped indium oxide are representative, but other oxide films, nitride films, carbide films, and boride films can also be used. Applicable.

In forming a film on the oxide transparent electrode 48 as described above, oxygen gas is introduced into the vacuum chamber as a reactive gas, nitrogen gas is introduced in the case of a nitride thin film, and carbide thin film is introduced into the vacuum chamber. In the case of methane gas (CI4), C02 gas, etc. are introduced, and in the case of boride, diporane gas (fbH) is introduced.
6) etc. are introduced, and a desired thin film is formed by reactive sputtering.

For example, in the case of a transparent conductive thin film of tin oxide, reactive sputtering is performed using a target made of a 5n-Sb alloy and oxygen gas as a reactive gas to form a transparent conductive thin film of tin oxide doped with Sb. In the case of an indium oxide transparent conductive wire film, a target made of an In-5O alloy and oxygen gas as a reactive gas are used to perform reactive sputtering to form a Sn-doped transparent conductive indium oxide film. Forms a thin film.

For example, when forming a tin oxide transparent conductive thin film, the target material may be Sn alone or 5n-3b.
, or an alloy of 5n-B is used.

In addition, when forming an indium oxide transparent conductive thin film, In alone, In-9n, In-P or In
-9n-P alloy is used to form a ZnO transparent conductive thin film, Zn alone or a Zn-Al alloy is used.

[Function] According to the present invention, a high-frequency coil is disposed between the target and the substrate, and the high-frequency coil generates high-frequency plasma, thereby introducing sputtering gas,
Alternatively, as the reactivity between the sputtering gas and the reactive gas increases, some of the sputtered particles passing through the plasma are also ionized. This allows the thin film to be deposited on the substrate in a more reactive state, resulting in higher quality t'Jj It2.
Nosuginari can be done.

In addition, with normal magnetron sputtering equipment, 2X
At 103 Torr or less, it becomes difficult to sustain the discharge, and the ion density also decreases, making sputtering difficult.

However, by adding high frequency plasma, 2X 104T
It becomes possible to emit Ti even close to orr. On the other hand, 2X
At 103 Torr, the self-uniform travel of the particles is greater than the device size, so after the particles fly out from the target, they collide with gas molecules and gas ions that cause film quality deterioration until they reach the substrate. can be ignored. In addition, since the oxygen partial pressure is also lowered, oxidation of the target, which causes poor film quality, becomes less likely to occur.

[Example] An indium oxide transparent conductive film was formed by the following method using a magnetron type sputtering apparatus as shown in FIG. In:9 as a sputtering source target
0 wt%, Sn: 10 wt% alloy used 1, =
For film formation, after reducing the pressure in the vacuum chamber to 5X 1O-6 Torr, a mixed gas of oxygen and argon (mixing ratio of approximately 1
:3) is introduced into a vacuum chamber, and the pressure inside the chamber is LX 1
0" Tarr, apply a voltage to the magnetron using a bias power source to start discharging the target, and further apply a high frequency voltage to the high frequency coil to generate high frequency plasma and activate the sputtered particles. An indium oxide transparent conductive film (film thickness: 1,000 layers) was formed on a glass substrate E at room temperature at a deposition rate of about 100 mm/min.In addition, in this single layer formation, the input power to the high frequency coil was too low. Furthermore, in order to positively increase the plasma potential, a DC resistor (80, Ω) was connected between the coil and ground via a high-frequency choke coil.

As a result, the obtained indium oxide transparent conductive film was transparent, had no absorption, and had a specific resistance 2X higher than that produced by the conventional method (OW using high-frequency power to a high-frequency coil) made under the same conditions.
The obtained film was comparable to that of a film formed on a 10-4ΩC film and a high-temperature substrate (300°C).

[Effects of the Invention] When forming a thin film by sputtering, the present invention generates high-frequency plasma using a high-frequency coil provided between a sputtering source and a substrate, and separates sputtering particles and sputtering gas, or sputtering gas and reactive gas. is in a more activated state, and has the effect that a thin +12 layer can be deposited on the substrate in this state.

In particular, the effect of forming a homogeneous and high-quality fJJl pattern on a substrate kept at a relatively low temperature is also recognized.

According to the present invention, as described in E, the high frequency introduction electrode is further grounded via a high frequency choke coil and a DC resistance, and the DC resistance level between this high frequency introduction electrode and the ground is controlled. , the plasma potential of the high-frequency discharge plasma is maintained at a positive potential with respect to the ground potential, and as a result, the plasma, the substrate or the substrate holder, and the substrate can be easily connected to each other even when the substrate or the substrate holder is grounded without particularly applying a direct current bias. The energy of positive ions incident on the substrate can be controlled by the potential difference between them.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an example of a sputtering apparatus used to carry out the present invention. 1 varnish batter device, 2 2 substrates, 3: bell jar, 4: vacuum chamber, 5: target, 6: magnetron, 7: substrate holder, 8: substrate, 9: high frequency coil, 10: high frequency source. 11: 'Rocking capacitor, 12: High frequency choke coil, 13: DC resistance 1
figure

Claims (4)

[Claims] (1) In a sputtering method in which a high-frequency discharge plasma is formed by providing a high-frequency coil between a substrate and a metal or metal alloy target, and sputtered particles are passed through the plasma to form a film, the above-mentioned high-frequency The coil is grounded via a high frequency choke coil and a DC resistance, and the plasma potential of the high frequency discharge plasma is maintained at a positive potential with respect to the ground potential by controlling the DC resistance level between the high frequency coil and the ground. A method for producing a transparent conductive oxide film. (2) The method for producing a thin film according to claim 1, wherein the thin film is an indium oxide transparent conductive thin film containing tin. (3) The method for producing a thin film according to claim 1, wherein the thin film is a tin oxide transparent conductive film containing antimony or fluorine. (4) Sputtering pressure is 2×10^-^4~3×10^-
3. The method of manufacturing a thin film according to claim 1, wherein the pressure is 3 Torr.