JPH066786B2 - Thin film forming equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus for forming thin films of various materials on a sample substrate by sputtering, and in particular, various thin films can be formed using high density plasma. The present invention relates to a novel thin film forming apparatus for continuously forming stably at high speed and high efficiency for a long time.

[Conventional technology]

Conventionally, at least one kind of gas is used as a raw material,
A so-called plasma chemical vapor deposition (P-CVD) method of forming a film by decomposing the gas in plasma and depositing it on the substrate or reacting it, or sputtering a target as a thin film forming element in plasma A so-called sputtering apparatus for forming a film by using the above is widely used in various fields for forming a thin film of various materials.

Further, in the sputtering apparatus, as shown in FIG. 5, a normal two-pole (rf, d) in which the target 1 and the substrate 2 are opposed to each other
c) A sputtering apparatus is the most common, and the vacuum chamber 4 having the target 1 and the substrate 2 to which the thin film is attached is composed of a gas introduction system and an exhaust system, and generates plasma inside the vacuum chamber 4 to sputter the target 1. Is.

On the other hand, the sputtering device shown in FIG.
ournal of Applied Physics, Vol.23, No.8, August, 1984,
pp.L534-L536. This apparatus combines sputtering of a cylindrical target 12 with high-density plasma using electron cyclotron resonance using microwaves and plasma transport with a divergent magnetic field of a magnetic field generating electromagnet 8,
A thin film is formed on the substrate 2.

[Problems to be solved by the invention]

The conventional thin film deposition system that combines microwave discharge and plasma transport by a divergent magnetic field shown in Fig. 6 enables high efficiency and high density plasma generation by electron cyclotron resonance (ECR), and can be used for several eV to several tens eV. It is a method that makes it possible to combine the extraction of low-energy ions with the realization of high-activity plasma at a high electron temperature, and is an excellent device that enables low-temperature production of various high-quality thin films. Moreover, 10 ^-4
Various reactive gases were used because it is possible to achieve low gas pressure discharge in the range of ~ 10 ^-5 Torr and to form an electrodeless discharge that does not use electrodes for plasma generation or filaments for thermionic emission. It is also possible to continuously form a stable film for a long time.

However, in the above-described thin film forming apparatus, when a metal or another conductive material is to be deposited as a forming film material, the film is not only formed on the target substrate, but also on the microwave introduction window made of quartz or the like. However, as a result, the microwave for plasma generation is reflected by the microwave introduction window, which makes it difficult to generate plasma. As described above, the above-described device has a great problem that the conductive material film cannot be stably formed for a long time despite having various excellent characteristics. It was limited.

Therefore, an object of the present invention is to solve the above-mentioned conventional problems and to provide a thin film forming apparatus capable of continuously forming a conductive film on a target substrate by sputtering continuously for a long time. .

[Means for solving problems]

In order to achieve such an object, the thin film forming apparatus of the present invention includes a plasma generation chamber, a vacuum chamber having a gas inlet which is coupled to the plasma generation chamber, and has a sample chamber having a substrate holder therein, and plasma generation. A magnet, which is provided on the outer circumference of the chamber, forms a magnetic field parallel to the side wall of the plasma generation chamber, and forms a magnetic field that diffuses toward the substrate holder, and one end is coupled to the microwave waveguide through the microwave introduction window. Is
The other end is provided with a vacuum waveguide which is connected to the plasma generation chamber in a direction perpendicular to the magnetic flux formed in the plasma generation chamber by the magnet, and the microwave introduced into the vacuum chamber resonates in the plasma generation chamber. A plasma generation chamber having a diameter and a length forming a cavity, and a target for sputtering are provided between the plasma extraction window and the substrate holder.

[Work]

According to the thin film forming apparatus of the present invention, since the plasma does not diffuse in the direction perpendicular to the magnetic flux, the microwave introduction window is prevented from being exposed to the plasma. Therefore, as compared with the conventional case where the microwave introduction window is installed at a position orthogonal to the magnetic field, the contamination of the microwave introduction window can be significantly reduced. In addition, since the microwave introduction window is installed outside the side wall of the plasma generation chamber, contamination of the microwave introduction window due to a part of plasma seeping out in the vacuum waveguide direction is reduced. further,
By making the microwave introduction window invisible from the sample chamber, it is possible to prevent particles spattering from the target by sputtering from adhering to the microwave introduction window, and it is also possible to form a conductive thin film for a long time by sputtering.

〔Example〕

 Embodiments will be described below with reference to the drawings.

FIG. 3 shows an example of a magnetic flux density distribution diagram in the magnetic flux direction of the thin film forming apparatus of the present invention.

The black circles in FIG. 3 indicate the magnetic flux density B corresponding to the position of this device shown in the same drawing. On the other hand, the direction of the vacuum waveguide 10, which is the direction of microwaves entering the plasma generation chamber 11, is perpendicular to the direction of the magnetic flux generated by the electromagnet 8, so that the plasma It does not diffuse across the magnetic flux in the direction orthogonal to the magnetic flux, and the plasma does not diffuse into the vacuum waveguide 10.

FIG. 4 shows a plasma generation state diagram in the thin film forming apparatus. FIG. 4 (A) is a plasma generation state diagram of the thin film forming apparatus of the present invention, and FIG. 4 (B) shows that the vacuum waveguide 10 is provided in the direction parallel to the magnetic flux and the microwave introduction window is simply generated. It is a plasma generation state diagram at the time of installing apart from a chamber. In FIGS. 4 (A) and 4 (B), the point cloud indicates plasma, and the high density portion of the point cloud indicates high plasma density. In FIG. 4 (B), when only the vacuum waveguide 10 is used, the EC inside the vacuum waveguide 10
Since the magnetic flux density of the R condition is satisfied, and the plasma is generated there, the microwave power is not effectively supplied into the plasma generation chamber 11, and the nonuniform plasma is generated. At the same time, since the divergent magnetic field is formed from the vacuum waveguide 10 in the microwave introduction window direction, the plasma is accelerated not only in the substrate direction but also in the microwave introduction window direction. On the other hand, in the configuration of the present invention in FIG. 4 (A), the vacuum waveguide 10 is connected to the plasma generation chamber at right angles to the magnetic flux direction formed by the electromagnet 8, and the plasma is generated. As a result, the plasma is not accelerated toward the microwave introduction window because it does not diffuse orthogonally to the magnetic flux.

Embodiment 2 FIG. 11 is a schematic configuration diagram of a sputtering apparatus which is an embodiment of the thin film forming apparatus of the present invention, and FIG. 2 is a perspective sectional view of the sputtering apparatus of the present invention shown in FIG. The vacuum chamber 4 comprises a vacuum waveguide 10, a plasma generation chamber 11 and a sample chamber 9.
In addition, microwaves are sequentially supplied to the vacuum chamber 4 through a microwave introduction window 6 from a microwave waveguide 7 and a microwave source connected to a microwave introduction mechanism such as a matching device, a microwave power meter, and an isolator (not shown). . The vacuum waveguide 10 is coupled to the plasma generation chamber 11 so as to be orthogonal to the magnetic flux direction generated by the magnetic field generating electromagnets 8 arranged around the plasma generation chamber 11. In the example, the microwave introduction window using the quartz glass plate was installed in a portion that was not directly visible from the sample chamber 9. As a microwave source,
For example, by using a magnetron of 2.45GH _z.

In the sample chamber 9, between the plasma extraction window 16 and the substrate holder 15, there is provided a target target that surrounds the plasma to which a negative voltage can be applied, or at least it is arranged so as to face the plasma. One flat plate target is provided. A gas such as Ar is introduced into the plasma generation chamber 11 to generate plasma, and the particles are used to sputter a target to deposit a film on the substrate 2.

The plasma generation chamber 11 and the vacuum waveguide 10 are water-cooled to prevent a temperature rise due to plasma generation. A gas introduction system (not shown) is directly connected to the plasma generation chamber 11. Outside the plasma generation chamber 11, the substrate 2 is placed in the direction of the magnetic flux by the electromagnet 8, and a shutter (not shown) is arranged on the substrate 2 so that the plasma 3 can be blocked. A heater is built in the substrate holder to heat the substrate 2. Further, a direct current or an alternating current voltage can be applied to the substrate 2 to perform substrate bias during film formation and sputter cleaning of the substrate.

The plasma generation chamber 11 employs, as an example, a circular copper-copper resonance mode TE ₁₁₃ as a condition of the microwave cavity resonator,
A cylindrical shape with a diameter of 20 cm and a height of 20 cm was used as the inner paste to enhance the electric field strength of microwaves and enhance the efficiency of microwave discharge. At the lower end of the plasma generation chamber 11, that is, on the surface leading to the substrate portion, there is a hole with a diameter of 10 cm as the plasma extraction window 16, the surface also serves as a reflection surface for microwaves, and the plasma generation chamber 11 has a cavity resonator. Acting as.

An electromagnet 8 is arranged on the outer circumference of the plasma generation chamber 11, and the intensity of the magnetic field generated by the electromagnet 8 is determined by the conditions of electron cyclotron resonance (ECR) by microwaves.
It is decided so that it will be established inside. For example the frequency 2.45GH _Z
For microwaves, the ECR condition is magnetic flux density 875
Since it is G, its magnetic flux density of 875 G
Is realized somewhere inside the.

Next, the result of forming an Al film using the sputtering apparatus of the present invention will be described. The degree of vacuum in the sample chamber 9 is set to 5 × 10 ^-7 To
After exhausting to rr, Ar gas was introduced at a flow rate of 30 cc / min, the gas pressure in the plasma generation chamber 11 was set to 5 × 10 ⁻⁴ , microwave power was 100 to 500 W, and power was supplied to the cylindrical Al target 12. Of 100 to 500 W and the magnetic field gradient as a divergent magnetic field gradient to form a film. At this time, a film was formed at room temperature without heating the sample table. As a result, the Al film could be stably and efficiently deposited continuously for a long time at a deposition rate of 60 to 300 nm / min. In the conventional apparatus shown in FIG. 6, when an Al film is formed at a deposition rate of 300 nm / min, the film can be continuously formed for only 2 minutes. It was possible to continuously and stably form an Al film having a thickness of.

The average energy of the ions at this time varied from 10 eV to 30 eV, and about 15% of the Al particles flying toward the substrate were ions.

The thin film forming apparatus of the present invention can be used not only for forming an Al film but also for forming almost all thin films, and can use almost any reactive gas as a gas to be introduced, thereby realizing reactive sputtering. I can.

In the embodiment of the apparatus of the present invention, no magnetic field is particularly applied to the target, but by combining an appropriate magnetic flux on the target surface and efficiently confining the electrons on the target surface, it is possible to combine it with magnetron discharge. It can also be used as a higher speed sputtering device.

〔The invention's effect〕

As described above, the present invention uses microwave discharge by electron cyclotron resonance for plasma generation, accelerates plasma in the sample chamber direction by a divergent magnetic field gradient in which the magnetic field strength changes slowly, and achieves high efficiency in low gas pressure. In contrast to the conventional method, which is impossible to form a conductive film continuously and stably for a long time, the present invention has a microwave introduction window. Connect the vacuum waveguide in a direction orthogonal to the magnetic flux in the plasma generation chamber, and use the vacuum waveguide to exude the microwave introduction window directly from the sample chamber or the microwave introduction window for sputtered particles. The haze can be removed, and the film can be continuously formed by sputtering regardless of the conductivity of the film. Furthermore, since the energy of particles can be freely controlled in a wide range from several eV to several tens of eV and a highly active plasma is used, this device can be used to obtain a good quality film with little damage at a low substrate temperature. It can be formed at high speed and high stability.

In the present invention, the magnetic field required for ECR is obtained by the electromagnet, but it is clear that the same effect can be obtained by using various permanent magnets or yokes or by combining them.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a sputtering apparatus which is an embodiment of the thin film forming apparatus of the present invention, and FIG. 2 is a perspective sectional view of the sputtering apparatus which is an embodiment of the thin film forming apparatus of the present invention shown in FIG. FIG. 3 is a magnetic flux density distribution diagram in the magnetic flux direction of the thin film forming apparatus of the present invention, FIGS. 4 (A) and 4 (B) are schematic diagrams of plasma generation states in the thin film forming apparatus, and FIG. FIG. 6 is a schematic diagram of a conventional sputtering apparatus. 1 ... Target, 2 ... Substrate, 3 ... Plasma, 4 ... Vacuum tank, 5 ... Magnetic flux, 6 ... Microwave introduction window, 7 ... Microwave waveguide, 8 ... Electromagnetic field generating electromagnet, 9 ... Sample chamber, 10 ... Vacuum Waveguide, 11 ... Plasma generation chamber, 12 ... Cylindrical target,

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiaki Takenouchi 1-29-13 Nishirokugo, Ota-ku, Tokyo Inside Dainichi Vacuum Laboratory (56) Reference JP-A-57-133636 (JP, A) JP-A-60-135573 (JP, A) JP-A-61-87869 (JP, A) JP-A-59-93874 (JP, A)

Claims (1)

[Claims] 1. A vacuum chamber having a plasma inlet, a gas inlet connected to the plasma outlet, and a sample chamber having a substrate holder and a target formed of a sputtering material therein; Between the plasma generation chamber and the sample chamber, a magnet that is provided on the outer periphery of the generation chamber, forms a magnetic field parallel to the side wall of the plasma generation chamber, and forms a magnetic field that diffuses toward the substrate holder. A plasma extraction window is arranged, one end of which is coupled to a microwave waveguide through a microwave introduction window, and the other end of which is coupled to the plasma generation chamber in a direction perpendicular to the magnetic flux formed in the plasma generation chamber by the magnet. And a diameter and a length that form a microwave cavity resonator in which the microwave introduced into the vacuum chamber resonates. And the microwave introduction window is disposed at a position away from the inside of the plasma generation chamber toward the outside and at a position that is not directly visible from the sample chamber. apparatus.