JPH10195646A - Sputtering method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sputtering method capable of forming a high quantity metallic compound film having a desired property. SOLUTION: This sputtering method is to form the metallic compound film on a substrate by impressing DC power to a metallic target in a reaction gas atmosphere to sputter by DC sputtering method. In such a case, transition time from point A, where DC power is stopped after film forming, to point B, where DC power is diminished and vanishes, is controlled to <=1msec.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering method for forming a metal compound film used on a liquid crystal display device or the like on a substrate.

[0002]

2. Description of the Related Art Generally, as a sputtering method for forming a film of a metal compound, a sputtering gas is introduced into a film forming chamber, high-frequency power is applied to a target made of the same metal compound as the target film, and plasma is generated. Raise
2. Description of the Related Art A high-frequency sputtering method for forming a metal compound film on a substrate by sputtering a target is known. However, the high-frequency sputtering method of a metal compound has a low film formation rate, especially when a large film area and a large film thickness are used.
There is a problem that the cost spent for film formation is significantly increased.

Therefore, a sputtering method in which a DC sputtering method using DC power is performed in a reactive gas atmosphere is effective in that a high film forming rate can be obtained. In this method, a sputtering gas including a reactive gas and an argon gas is introduced into a film forming chamber, and DC power is applied between a metal target constituting a film of a desired metal compound and a facing electrode on which a substrate is mounted. Then, a plasma is generated, a target is sputtered, and a metal compound generated by a reaction between a metal atom and a reactive gas ion is deposited and grown on a substrate to form a metal compound film.

[0004] In order to form a high-quality film with few defects, it is effective to perform batch processing by adjusting film forming conditions every time a film is formed. In order to form a film by the batch process, a sputtering apparatus of a type in which there is no mechanically operated shutter or the like which causes dust in a film forming chamber held in a vacuum is effective.

[0005]

However, when a film is formed using the above-described sputtering apparatus, the supply of the DC power applied to the target is turned on / off every time the film is formed on the loaded substrate. There is a need to. A DC power supply provided in a conventional sputtering apparatus usually has a stabilizing circuit for stabilizing its output, and has a large capacitance at its output terminal. Therefore, when the supply of the DC power is stopped when the predetermined film thickness is reached, several tens to several hundreds of milliseconds are required for a transition time until the DC power attenuates and disappears. For example, when indicated by a broken line in FIG.
The film was formed with a DC current value of 20 amps, and the transition time required from point A, at which a predetermined film thickness was reached and power supply was stopped, to point C, at which 0 amps was reached, was about 35 milliseconds.

However, the metal atoms of the metal target sputtered during the transitional time until the DC power is attenuated / dissipated cannot obtain the energy required for the reaction with the reactive gas ions and is released by sputtering. Unreacted metal atoms are deposited and grown as they are, and a film with metallic properties gradually grows in the metal compound film, and the desired electrical and chemical properties cannot be obtained in the metal compound film. is there.

Further, in order to prevent unreacted metal atoms from reaching the substrate from the metal target, a mechanical operation is performed when a predetermined film thickness is reached during film formation with regular DC power. It is also conceivable to stop sputtering or deposition of a film using a shutter that covers the target or the substrate, but in this case, if a shutter or the like is introduced into the film formation chamber, dust is generated due to the operation and high quality There is a problem that a film of the metal compound cannot be obtained.

The present invention solves the above-mentioned problems of the conventional sputtering method and provides a sputtering method for efficiently depositing a high-quality metal compound film having desired electrical and chemical properties. The purpose is to:

[0009]

According to the present invention, there is provided a sputtering method for applying a direct current power to a metal target by a direct current sputtering method in a reactive gas atmosphere to form a metal compound film on a substrate by sputtering. The method is characterized in that the transient time after stopping the DC power at the end of the film formation is set within 1 millisecond.

According to the sputtering method of the present invention, when the film formation is completed when a predetermined film thickness is reached, the transient time after stopping the DC power is set within 1 millisecond. A metal compound film having chemical properties can be obtained, and the film formation can be completed electrically without relying on a mechanical operation, so that a high-quality metal compound film can be obtained.

In this sputtering method, when the DC power is stopped when a predetermined film thickness is reached, and when a transition time of 1 ms or more is required until the DC power attenuates and disappears, the metal compound film is removed. When the metal material is deposited as it is, a film having electrical characteristics such as a desired resistance value and chemical characteristics such as an etching rate cannot be obtained. The properties are negligible, and the desired properties of the metal compound as a film can be obtained.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The sputtering method according to the present invention does not have a mechanically operating mechanism in a film forming chamber, reduces the generation of dust during film formation, and can form a high-quality film by batch processing. Using a sputtering apparatus, a sputtering gas composed of a reactive gas such as oxygen and nitrogen and an inert gas such as argon is introduced into the film forming chamber, and direct current power is supplied to a metal target attached to a target electrode in the film forming chamber. Is applied to generate a plasma, and a metal target is sputtered to cause a reaction between a metal atom in a high energy state and a reactive gas ion, thereby keeping the metal compound generation rate at a high value and depositing the metal compound on a substrate. Is a sputtering method in which a DC power is stopped when a predetermined film thickness is reached and a desired metal compound film is formed. Is stopped, and the transient time until the DC power is attenuated and disappears is stopped within 1 millisecond, and the sputtering is stopped instantaneously to prevent unreacted metal atoms from depositing on the substrate as they are from the metal target. This is a method of forming a high-quality metal compound film having desired electrical and chemical properties.

As for the sputtering apparatus used in the present invention, there is no mechanical operation that causes dust generation in the film forming chamber, and the substrate is placed in the film forming chamber that can be maintained at a high vacuum every time a film is formed. Is carried out, a vacuum is formed, a film is formed by adjusting the conditions in the film formation chamber, and then the substrate on which the film is formed is removed from the film formation chamber, as long as a high-quality film can be formed by batch processing. In particular, a multi-chamber type single-wafer sputtering apparatus capable of performing a series of film forming processes efficiently in an environment under reduced pressure is preferable. This apparatus has a plurality of processing chambers such as a load lock chamber for loading and unloading the substrate, a pretreatment chamber for heating the substrate to remove molecules such as water adsorbed on the surface thereof, and a deposition chamber for performing deposition by sputtering. But,
Arranged around transfer chambers equipped with a transfer device for transferring the substrate to each chamber, each chamber is connected to a vacuum pump and maintained at a high vacuum, and is connected to the transfer chamber via a separately provided gate valve. It is designed to communicate. This single-wafer device
The transfer chamber equipped with a mechanically operated transfer machine and each chamber are isolated by a gate valve and can be maintained at a high vacuum, so that dust can be prevented and a high-quality film can be formed. is there.

As the DC power supply provided in the sputtering apparatus used in the present invention, when the supply of DC power is stopped while maintaining stable output characteristics, the transient time until the DC power attenuates and disappears thereafter Should be within 1 millisecond.

As the metal target, a metal material having good conductivity and reactivity such as chromium, tantalum, titanium, and nickel chromium can be used. In particular, chromium, which has a high adhesion to a glass substrate, is preferable.

The sputtering gas comprises a reactive gas and an inert gas such as argon. As the reactive gas, depending on the type of the desired metal compound, oxygen, nitrogen,
Gases having reactivity with metals such as carbon dioxide and hydrocarbons can be used. As the inert gas, argon or the like for adjusting the partial pressure of the reactive gas to sputter the target is used.

[0017]

FIG. 1 is an explanatory view showing a sputtering apparatus for forming a film by batch processing used in this embodiment. In this figure, 1 is a target made of metallic chromium,
2 is a metal chromium particle, 3 is a sputtering gas composed of a reactive gas 4 and an argon gas 5, 6 is a substrate made of borosilicate glass, 7 is a chromium compound generated by the reaction, and 8 is a chromium compound film. 11 is a film forming chamber,
Reference numeral 20 indicates a DC power supply.

In this sputtering apparatus, as shown in FIG.
1, a gas inlet 12 for introducing the target 1, a target electrode 13 to which a target 1 made of chromium metal is attached, and to which DC power is applied,
An insulator 14 for insulating the target electrode 13 from the substrate a, a substrate holder 15 for holding the substrate 6 carried into the film forming chamber 11 and also serving as a counter electrode, and an exhaust port 16 connected to a vacuum pump for performing vacuum exhaust. And a high-quality film can be formed.

In the apparatus of this embodiment, the DC power source 20 holds the target electrode 13 on which the target 1 made of chromium metal is mounted and the substrate 6 made of borosilicate glass which is carried in and serves as a counter electrode. While maintaining the characteristics as a basic DC power supply, for example, the arc countermeasure of the switch in the DC circuit and the capacity of the capacitor 20a at the output end are within a range that does not impair the stability of the power supply output. Use one that takes measures such as reducing the size. The value of the current for monitoring the output power of the DC power supply 20 is shown by the solid line in FIG. This figure shows the relationship between the current value and the time when the DC power of the power supply is cut off after performing the sputtering by setting the output of the DC power supply 20 to 10 kW. In this case, the transition time required from the point A at 20 amps to the point B at which the amperage of DC power at which the power supply is stopped becomes 20 amps is about 70 microseconds, which is reduced to 1/500 of the conventional value. I have.

(Embodiment 1) DC power supply 2 having the above characteristics
A chromium compound film 8 made of chromium oxide was formed on the substrate 6 as a thin-film resistor using a sputtering apparatus equipped with a chromium oxide. First, the substrate 6 cleaned by heating to about 200 ° C. in the pretreatment is carried into the film forming chamber 11 and is held on the substrate holding table 15. 11 was vacuum-sealed. Next, a reactive gas 4 composed of oxygen and a sputtering gas 3 composed of an argon gas 5 are introduced through a gas inlet 12 to adjust the sputtering gas pressure in the film forming chamber 11 to 1.1 Pascal, and to reduce the DC power to 10 Pa. Set to kW and target 1
Chromium oxide is deposited on the substrate 6 as a chromium compound 7 by reacting the metal chromium atoms 2 in a high energy state with the ions of the reactive gas 4 composed of oxygen, and the film thickness reaches 100 nm. At this point, the DC power was cut off to stop sputtering to form a chromium compound film 8, and the film formation was completed. The electrical characteristics of the chromium compound film 8 made of chromium oxide obtained by this film formation were measured by using a metal chromium film previously provided as an electrode on the substrate 6 using an aluminum electrode having an area of 0.01 cm ^2. The voltage of 5 V was applied between the electrodes, and the value of the current flowing between the electrodes is shown in the upper part of Table 1.

Example 2 Next, a film 8 of a chromium compound of oxygen, nitrogen and carbon used for a color filter of a liquid crystal display was formed using the same sputtering apparatus as described above. The substrate 6 made of borosilicate glass heated to about 200 ° C. and cleaned in the pretreatment is carried into the film forming chamber 11 and held on the substrate holding table 15, and the vacuum vessel 11 a is sealed and exhausted from the exhaust port 16. The film forming chamber 11 was vacuum-sealed. Next, a sputtering gas 3 consisting of a reactive gas 4 containing a mixture of oxygen, nitrogen and carbon dioxide and an argon gas 5 is introduced from the gas inlet 12 into the film forming chamber 11, and the sputtering gas in the film forming chamber 11 is formed. The pressure is adjusted to 0.8 Pa, the DC power is set to 10 kW and applied to the target 1 to perform sputtering, and the metal chromium atoms 2 in a high energy state react with the ions of the reactive gas 4 to generate The chromium compound 7 thus deposited was deposited on the substrate 6, and when the film thickness reached 60 nm, DC power was cut off and sputtering was stopped to form a chromium compound film 8, and the film formation was completed. As values representing the chemical characteristics of the chromium compound film 8 obtained by this film formation, a standard etching solution (a solution consisting of 5% by volume of perchloric acid and 95% by volume of water, 170 g of ceric ammonium nitrate per liter) was used. The rate of decrease of the film thickness when immersed in a solution in which the film was dissolved was shown as an etching rate.
Is shown at the top.

[0022]

COMPARATIVE EXAMPLE As shown by a broken line in FIG. 2, a DC power supply having a characteristic that it takes about 35 ms for the current output value of DC power to change from 20 amps to 0 amps and disappear is used. A film of chromium oxide and a film of a chromium compound with oxygen, nitrogen, and carbon were formed in the same manner as in Examples 1 and 2, and a voltage of 5 V was applied to the obtained chromium oxide film to form an electrode. The lower part of Tables 1 and 2 shows the value of the current flowing therethrough, the etching rate of the chromium compound film, and the sheet resistance thereof.

[0023]

[Table 1]

[0024]

[Table 2]

As shown in Table 1, the current value of the chromium oxide film according to the conventional method is 1.3 amps / cm ^2, which is very high due to the metal chromium deposited when the DC power is turned off. Has become. On the other hand, the current value of the chromium oxide film according to the present invention is 0.0002 amp / cm.
^{2, which} is sufficiently low and has desired electrical characteristics. Further, as shown in Table 2, the film of the chromium compound with oxygen, nitrogen, and carbon according to the conventional method has a strong metallic property as can be seen from the low sheet resistance value, and therefore, the etching rate is 1100 nm. And faster. In contrast, the film of the metal compound according to the present invention is
Sufficiently 800 nm / min, the desired chemical properties are obtained.

[0026]

According to the sputtering method of the present invention, a practically excellent effect of efficiently forming a high-quality metal compound film having desired electrical and chemical characteristics can be obtained. is there.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a sputtering apparatus used in the present invention.

FIG. 2 is a diagram showing current output characteristics of a DC power supply according to the present invention and a conventional DC power supply.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Target 2 Chromium metal atom 3 Sputtering gas 4 Reactive gas 5 Argon gas 6 Substrate 7 Metal compound 8 Metal compound film 11 Film formation chamber 20 DC power supply

Claims (1)

[Claims] In a sputtering method in which a DC power is applied to a metal target by a DC sputtering method in a reaction gas atmosphere to form a film of a metal compound on a substrate by sputtering, the DC power is stopped when the film formation is completed. A sputtering method characterized in that the subsequent transient time is within 1 millisecond.