JPH0715145B2 - Sputtering device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering apparatus, and more particularly to a sputtering apparatus using a microwave and a magnetic field.

Conventional technology Conventionally, a high-ionization plasma is formed using a microwave and a magnetic field, an electric field is applied to the ions in the plasma, and the target is irradiated with high-speed ions to cause a sputtering phenomenon to cause a thin film formation. Is well known.
[JAPAN JOURNAL OF APPLIED PHYSICS] Vol.23, No.
8, AUGUST, 1984, pp. L534-L536, JP-A-60-50167]
As one of the conventional examples, a schematic view of the apparatus is shown in FIG. As a basic configuration, a plasma chamber 12 for generating plasma and a film forming chamber 13 for forming a thin film on the substrate 6 are provided as two chambers, and a target 14 is provided inside the film forming chamber 13 to configure the apparatus. . Such a configuration is to allow the generation of ions in the plasma chamber 12 and the sputtering phenomenon in the film forming chamber 13 to be independently controlled by using the plasma chamber 12 as an ion generation source. That is, by applying to the plasma chamber 12 a magnetic field under the electron cyclotron resonance (ECR) condition generated by the microwave and the electromagnet 8 (in the case of the microwave frequency f0 = 2.45 GHz, the ECR condition magnetic field B0 = 0.0875T). , Form a plasma. This plasma flows into the film forming chamber 13 through the extraction window 15 along the magnetic field application direction 11. While flowing out, the target 14 having a negative potential with respect to the plasma is irradiated with the ions in the plasma to cause a sputtering phenomenon. Here, the target 14 has a right cylindrical shape or a conical shape. Then, the sputtered target material enters the plasma and reaches the substrate 6 together with the plasma while being ionized. As a result, a compound that is reacted and synthesized with the target substance or the substance in the plasma is formed on the substrate 6. When an aluminum oxide film is formed on the substrate 6 with such a structure, a dense film can be obtained at high speed.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-described configuration, among the high-ionization plasma formed in the plasma chamber by the microwave and the magnetic field, only some ions flowing out from the extraction window are used as the target sputtering. However, there is a problem that the deposition rate is kept low. Further, the number of ions decreases as the ions flowing out along the magnetic field application direction progress in the magnetic field application direction. For this reason, when a straight cylindrical or conical target is placed in the direction of the magnetic field application, the sputtering phenomenon occurs only near the outflow of plasma, and only part of the target contributes to film formation, so the deposition rate is kept low. There was a problem that it would be lost.

In addition, highly reactive particles that are highly excited in the plasma chamber (usually the lifetime of excited particles is several tens of nanoseconds),
There is a problem that the film quality is deteriorated by decaying to a low excited state or a metastable state before reaching the target or the substrate surface. Further, there is a problem that the constituent material of the wall surface is mixed as an impurity in the film due to the sputtering of the wall surface caused by the ions and the high-speed neutral particles in the plasma chamber, and the film quality is deteriorated.

As described above, in the two-chamber configuration of the plasma chamber and the film forming chamber, the ion source control and the film formation control including the sputtering phenomenon were independently performed. An object of the present invention is to provide a sputtering apparatus that enables independent control of ion generation and film formation even in one chamber, and enables high-speed deposition and high-quality film formation.

Means for Solving the Problems The present invention is a sputtering apparatus in which a microwave and a magnetic field are applied in a cylindrical vacuum chamber, in which at least one type of target is arranged inside the vacuum chamber and microwaves are generated outside the vacuum chamber. A mode converter that fixes at least one propagation mode is provided, and the target is placed in the periphery of the vacuum chamber where microwaves are introduced and on the inner surface in the outer peripheral direction with respect to the magnetic field application direction. This is a sputtering device using the circular TM mode.

The present invention applies a microwave and a magnetic field in a cylindrical vacuum chamber, arranges a plurality of targets of at least one type inside the vacuum chamber, and has at least one microwave propagation mode outside the vacuum chamber. Provided with a mode converter fixed to, the target is arranged on the inner surface in the outer peripheral direction with respect to the direction in which the magnetic field is applied, in the vicinity where the microwave is introduced into the vacuum chamber.
In a sputtering device that uses the circular TM mode as the propagation mode, the targets are electrically separated in the direction of the magnetic field application and are arranged in a stack, and the cross-sectional shape of the mode converter and the cross-sectional shape of the target are almost the same. Is.

Action The present invention has the above-described structure to form a plasma with high ionization, irradiate the target with ions in the plasma to cause a sputtering phenomenon, and form a thin film on the substrate.

That is, when microwave and magnetic field are applied in the vacuum chamber,
Highly ionized plasma is generated. Since this highly ionized plasma is highly ionized near the periphery where the microwave is introduced into the vacuum chamber, a large number of ions are present around the introduction. Therefore, by arranging the target around this, a large amount of ions can be supplied to the target. Thereby, the control of the plasma is performed by the power of the microwave and the magnetic field density, and the control of the sputtering phenomenon is performed by the control of the potential of the target. From the above, even in one vacuum chamber, plasma and sputtering phenomena can be controlled independently,
It has the same function as the two-chamber structure.

The plasma is formed along the microwave propagation direction. That is, a higher density plasma can be formed at a position where the electric field strength of the microwave is higher. Especially,
Since the electric field distribution of the microwave in the circular TM mode is formed along the surface of the vacuum layer, if the target is arranged in a direction other than the microwave propagation direction, a high density plasma can be formed near the surface of the target, and a large amount of the target is generated. Ions can be supplied.

Further, by arranging the target on the surface of the inner surface of the vacuum chamber in a direction other than the magnetic field application direction, it is possible to clearly increase the surface area of the target as compared with the conventional case where the target is arranged outside the plasma chamber. Moreover, since the ions in the plasma can be effectively irradiated onto the target, the deposition rate can be increased.

In addition, by disposing the mode converter outside the vacuum chamber, the microwave propagation mode in the vacuum chamber can be fixed.
When a discharge is generated in the vacuum chamber, the density of ions is higher at a position where the electric field strength of the microwave is stronger, so it is important to fix the propagation mode of the microwave. Especially circular
The position where the electric field strength is strong near the surface of the vacuum layer as in the TM mode is effective in improving the deposition rate when the target is placed on the surface of the vacuum chamber.

In addition, highly reactive particles that are highly excited in the vacuum chamber reach the target or substrate surface in a short time,
Highly excited particles can contribute to the film formation and the sputtering phenomenon without being attenuated to a low excited state or a metastable state.

In addition, since the negative potential target is placed on the inner surface of the vacuum chamber, it is possible to prevent impurities from being mixed into the film due to the sputtering of the walls of the vacuum chamber caused by the ions and high-speed neutral particles in the plasma. You can

Further, when the target is arranged in the direction of applying the magnetic field, the discharge is concentrated in the vicinity of the introduction of microwaves and the sputtering phenomenon is also concentrated. However, the problem is solved by adjusting the applied voltage to each target by electrically separating and arranging multiple targets and making the cross-sectional shape of the mode converter equal to the cross-sectional shape of the target. it can. Even in the case where the sputtering rate is different due to different kinds of targets, the same problem can be solved by disposing a plurality of targets.

Embodiment An embodiment of the present invention will be described with reference to FIG. 1 with reference to the drawings. FIG. 1 is a schematic view of an apparatus according to an embodiment of the present invention. The numbers in the figure that are the same as those in FIG. 5 are given the same numbers. Reference numeral 1 is a vacuum tank, and 3 is a target.

Hereinafter, a microwave having a frequency f0 of 2.45 GHz is used.

As the vacuum chamber 1, a microwave circular waveguide having an inner diameter of 20 cm was used. A microwave was introduced into the vacuum chamber 1 using a circular TM01 mode microwave waveguide 2 as a mode converter.
TM01 mode microwave waveguide 2 has an inner diameter of 11 cm and a length of 28.3c
It was m. Circular TM mode microwave waveguide 2 is TMmn, TE
Higher-order mode of mn mode (in case of TM mode, m + n ≧ 2, TE
In the case of the mode, m + n ≧ 3 and circular TE01 mode) were set to the inner diameter that cannot be excited. Vacuum tank 1 and microwave waveguide 2
And are arranged so that they have the same central axis. The target 3 is arranged in the outer peripheral direction of the magnetic field application direction 11, and the surface of the inner surface of the vacuum chamber other than the magnetic field application direction 11 around the periphery where the microwave is introduced into the vacuum chamber 1, that is, the vacuum chamber 1. It was arranged near the inner diameter difference portion 18 with the circular TM01 mode microwave waveguide 2.

FIG. 2 shows a detailed view around the target 3. The target 3 is made of metal or conductive material and has an outer diameter of 16 cm,
The shape was 13 cm in inner diameter and 10 cm in height. The target 3 and the inner diameter difference portion 18 (vacuum chamber 1) are insulated by the insulating layer 4. The shield 5 covers a part of the target 3 with a gap from the target 3 so that the side surface of the target 3 is not sputtered. Reference numeral 19 is an insulating pipe, and 20 is a water cooling pipe. The sputtered portion was on the inner surface side of the target 3, and the sputtered area excluding the shield 5 portion was 330 cm ² .

Since high-density plasma is formed near the maximum of the electric field distribution in the circular TM01 mode, the target 3 is arranged near the maximum of this electric field. Also, the strength of the magnetic field satisfies the ECR condition by the electromagnet 8 (when f0 = 2.45 GHz, B0 = 0.
0875T). The distance between the substrate 6 and the target 3 is 15 cm
And

The formation of the aluminum oxide film will be described below by using the sputtering apparatus of this embodiment configured as described above.
Aluminum is used as the target 3, argon gas and oxygen gas are used as the sputtering gas, and each is 5 SCCM.
And the total pressure was 0.2 Pa. A glass substrate was used as the substrate 6. A power source 9 was connected to the target 3 and a DC voltage of −100 V was applied to the substrate holder 7. The microwave power was 400W. Under this condition, the current flowing through the target 3 was about 1.3 A and the current density was 4 mA / cm ² . The value of this current density is doubled compared to the conventional example, and the effect of placing the target 3 on the inner surface of the vacuum chamber in the direction other than the magnetic field application direction 11 and setting the microwave propagation mode to the TM mode is known. You can

Under the above conditions, the aluminum oxide film was formed at a deposition rate of 30 nm / min. This aluminum oxide film has a refractive index of 1.
It was a good quality film with a composition ratio of 76: Al: O = 2: 3. Further, in the aluminum oxide film, no metal other than aluminum as impurities could be detected. This means that the effect of covering the inner surface of the vacuum chamber 1 with the target 3 in a direction other than the magnetic field application direction 11 can be known.

Although the magnetic field strength satisfying the ECR condition is formed by the electromagnet 8 in this embodiment, the ECR condition may not necessarily be satisfied. A permanent magnet other than the electromagnet may be used as the means for generating the magnetic field.

In this embodiment, the apparatus is configured by using one target 3, but a plurality of targets may be arranged.

In this embodiment, a DC power source is used as the power source 9 and a metal or a conductive material is used as the target 3. However, an AC power source or a high frequency power source other than the DC power source may be used, and the target 3 may be an oxide, a carbide, A compound such as nitride may be used. For example, as a target, bismuth oxide,
Forming a composite oxide thin film using barium carbonate, strontium oxide, cuprous oxide, etc. is included in the present invention.

In this embodiment, a circular TM01 is used as a microwave propagation mode.
Although the mode is used, other modes may be used.

In this embodiment, argon gas and oxygen gas were used as the sputtering gas, but any inert gas other than argon gas may be used, and when forming an oxide, a gas containing oxygen other than oxygen gas may be used. Any gas may be used as long as it is a gas containing nitrogen or carbon when forming a compound such as a carbide or a nitride other than an oxide.

Another embodiment of the present invention will be described with reference to FIG. FIG. 3 is a schematic view of an apparatus according to another embodiment of the present invention. In the figure, the same numbers as those in FIG. 1 are given the same numbers. Reference numeral 1 is a vacuum tank, 2 is a circular TM01 microwave waveguide, 3 is a first target, 23 is a second target, and 29 is a second power source.

Hereinafter, a microwave having a frequency f0 of 2.45 GHz is used.

As the vacuum chamber 1, a cylindrical one having an inner diameter of 20 cm was used. A microwave was introduced into the vacuum chamber 1 using a circular TM01 mode microwave waveguide 2 as a mode converter. The circular TM01 mode microwave waveguide 2 has an inner diameter of 11 cm and a length of 28.3 cm.
Circular TM01 mode microwave waveguide 2 is circular TMmn, TEmn
The higher order mode (m + n ≧ 2 in TM mode, m + n ≧ 3 in TE mode and circular TE01 mode) is set to an inner diameter that cannot be excited. The vacuum chamber 1 and the circular TM01 mode microwave waveguide 2 were arranged so as to have the same central axis. The first and second targets 3, 23 are microwave vacuum chambers 1.
It was arranged in the periphery introduced inside, that is, in the vicinity of the inner diameter difference portion 12 between the vacuum chamber 1 and the circular TM01 mode microwave waveguide 2 and in the magnetic field applying direction 11.

FIG. 4 shows a detailed view around the first and second targets 3 and 23. The first and second targets 3 and 23 are made of metal or a conductive material and have a hollow cylindrical shape. The cross-sectional shapes of the first and second targets 3 and 23 and the circular TM01 mode microwave waveguide 2 are almost the same, that is, the first and second targets.
The inner diameter of 3,23 was set to 11 cm, which was the same as the inner diameter of the circular TM01 mode microwave waveguide 2, and the heights of both targets 3,23 were also set to 10 cm. The first and second targets 3 and 23 and the inner diameter difference portion 18 (vacuum chamber 1) are insulated by the insulating layer 4, and the first and second targets are similarly insulated. First and second target
The sputtered area of 3,23 was 345 cm ² .

The strength of the magnetic field was set so that the ECR condition was satisfied by the electromagnet 8 (B0 = 0.0875T when f0 = 2.45 GHz). The distance between the substrate 6 and the end face of the second target was 15 cm.

The formation of the aluminum oxide film will be described below by using the sputtering apparatus of this embodiment configured as described above.
Aluminum was used for both the first and second targets 3 and 23, argon gas and oxygen gas were used as the sputtering gas, and 5 SCCM of each was flowed at a total pressure of 0.2 Pa. A glass substrate was used as the substrate 6. The first power source 9 to the first target 3,
A second power source 29 was connected to the second target 23, and a DC voltage of −80, −200 V was applied to the substrate holder 6. Microwave power was approximately 300W. Microwave incident power Pμ to 300 W, reflected power Pref = 1 W and VSWR = 1.13. And this VSWR value was almost the same with or without discharge. It can be understood that the microwave power can be efficiently introduced into the vacuum chamber 1 as described above because the cross-sectional shape of the mode converter and the cross-sectional shape of the target are made equal.

Under this condition, the current flowing through the first and second targets 3 and 23 is almost
At 1.4 A, the current density was 4 mA / cm ² . The value of this current density is three times higher than that of the conventional example, and the first, second target 3,23
Can be seen on the surface of the inner surface of the vacuum chamber 1 in a direction other than the magnetic field application direction 11, and the effect of changing the microwave propagation mode to the TM mode can be seen. If multiple targets are not used, the current density is 3 mA / cm ² , and if the current density is increased beyond this (microwave power is constant), arc discharge will occur, and multiple targets will be arranged. You can know the effect.

Under the above conditions, the aluminum oxide film was formed at a deposition rate of 50 nm / min. This aluminum oxide film has a refractive index of 1.
It was a good quality film with a composition ratio of 76: Al: O = 2: 3. Further, in the aluminum oxide film, no metal other than aluminum as impurities could be detected. This makes it possible to know the effect of disposing a plurality of targets 3, 23 on the inner surface of the vacuum chamber 1.

Although the magnetic field strength satisfying the ECR condition is formed by the electromagnet 8 in this embodiment, the ECR condition may not necessarily be satisfied. A permanent magnet other than the electromagnet may be used as the means for generating the magnetic field.

In this embodiment, the shield is not used around the target, but the present invention also includes the shield arranged around the target.

In the present embodiment, the device is configured by using the two targets 3 and 23, but three or more targets may be arranged.

In this embodiment, a direct current power source is used as the power sources 9 and 29, and a metal or a conductive material is used as the target.However, an alternating current power source or a high frequency power source other than the direct current power source may be used, and an oxide, a carbide, or a target is used. A compound such as nitride may be used. Although a plurality of targets of the same type are used in this embodiment, different types of targets may be used. For example, as a target, bismuth oxide, barium carbonate,
Forming a composite oxide thin film using strontium oxide, cuprous oxide, etc. is included in the present invention.

In this embodiment, a circular TM01 is used as a microwave propagation mode.
Although the mode is used, other modes may be used.

In the present embodiment, argon gas and oxygen gas were used as the sputtering gas, but any inert gas other than argon gas may be used, and in the case of forming an oxide, any gas containing oxygen other than oxygen gas may be used. Well, when forming a compound such as a carbide or a nitride other than an oxide, a gas containing nitrogen or carbon may be used.

Effects of the Invention As described above, according to the present invention, a microwave chamber and a magnetic field are applied in a cylindrical vacuum chamber, the microwave chamber is introduced into the vacuum chamber, and the vacuum chamber is in the vicinity of the direction other than the magnetic field application direction. At least one type of target is arranged on the surface of the inner surface, a mode converter that fixes the microwave propagation mode to at least one is provided outside the vacuum chamber, and a simple configuration using the circular TM mode as the propagation mode is used. Since highly ionized plasma is formed on the surface of the target, the target can be irradiated with a large amount of ions, which has the effect of increasing the deposition rate. further,
Highly excited particles that are highly excited in the vacuum chamber reach the target or substrate surface in a short time, so that highly excited particles can be used for film formation or sputtering without being attenuated to a low excited state or a metastable state. It can contribute to the phenomenon and has the effect of improving the film quality.

Further, since the target of negative potential covers the surface of the inner surface of the vacuum chamber, it is effective in preventing impurities from being mixed into the film due to sputtering of the walls of the vacuum chamber caused by ions in plasma or high-speed neutral particles. is there.

If the relationship between the microwave and the magnetic field is made to satisfy the ECR condition, a plasma with high ionization is obtained and the deposition rate is further improved.

Further, the present invention applies a microwave and a magnetic field in the vacuum chamber,
Mode conversion that fixes multiple microwave propagation modes to at least one by arranging multiple targets of one or more types on the inner surface of the vacuum chamber where microwaves are introduced into the vacuum chamber in a direction other than the magnetic field application direction. The target is irradiated with a large amount of ions because a highly ionized plasma is formed on the surface of the target with a simple structure in which the cross-sectional shape of the mode converter and the cross-sectional shape of the target are installed outside the vacuum chamber. it can. Therefore, it has the effect of increasing the deposition rate.
Further, by electrically dividing the plurality of targets and arranging them in a stacked manner, only a part of the targets is not sputtered. This has the effect of increasing the deposition rate. Further, by fixing one microwave propagation mode, particularly the circular TM mode, it is possible to increase the ion density at the position where the electric field strength of the microwave is strong, which is effective in improving the deposition rate. Further, the microwave power can be efficiently introduced into the vacuum chamber by making the cross-sectional shape of the mode converter equal to the cross-sectional shape of the target.

As described above, the present invention has excellent effects,
The industrial value of the present invention is high.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a sputtering apparatus according to an embodiment of the present invention,
FIG. 2 is a detailed sectional view around the target of this embodiment, and FIG. 3 is a schematic sectional view of a sputtering apparatus of another embodiment of the present invention.
FIG. 4 is a detailed sectional view around the target of this embodiment, and FIG. 5 is a schematic sectional view of a conventional sputtering apparatus. 1 ... Vacuum tank, 2 ... Circular TM01 mode microwave waveguide, 3 ... First target, 23 ... Second target, 6
... substrate, 8 ... electromagnet, 9,29 ... power supply, 15 ... drawer window.

Claims (5)

[Claims] 1. In a sputtering apparatus in which a microwave and a magnetic field are applied in a cylindrical vacuum chamber, at least one kind of target is arranged inside the vacuum chamber, and at least the microwave propagation mode is provided outside the vacuum chamber. A mode converter fixed to one is provided, and the target is arranged in the periphery of the microwave chamber into which the microwave is introduced, and is arranged on the inner surface of the cylinder whose center axis is the application direction of the magnetic field. The sputtering system is characterized by the circular TM mode. 2. The sputtering apparatus according to claim 1, wherein the magnetic field substantially satisfies an electron cyclotron resonance (ECR) condition determined by the microwave frequency. 3. A microwave and a magnetic field are applied in a cylindrical vacuum chamber, a plurality of targets of at least one type are arranged inside the vacuum chamber, and a propagation mode of the microwave is provided outside the vacuum chamber. Providing a mode converter fixed to at least one, the target is arranged in the periphery of the vacuum chamber in which the microwave is introduced, and is arranged on the inner surface of the cylinder whose center axis is the application direction of the magnetic field, and the propagation is performed. In a sputtering device in which a circular TM mode is used as a mode, the targets are electrically separated in the magnetic field application direction and arranged in a stack, and the vertical cross-sectional shape of the mode converter and the vertical direction of the plurality of targets are arranged. The sputtering apparatus is characterized in that its cross-sectional shape is almost the same. 4. A circular TM01 as a microwave propagation mode.
The sputtering apparatus according to claim 3, wherein the sputtering apparatus is set to a mode. 5. The sputtering apparatus according to claim 3, wherein the magnetic field substantially satisfies an electron cyclotron resonance (ECR) condition determined by the microwave frequency.