JP5551635B2 - Thin film forming equipment - Google Patents

Description

  The present invention relates to a thin film forming apparatus for forming a thin film on a substrate using plasma.

Today, when a thin film is formed on a substrate, two kinds of gases mainly composed of elements constituting the thin film to be formed are alternately supplied onto the substrate, and the thin film is formed on the substrate in units of atomic layers. An ALD (Atomic Layer Deposition) technique for forming a film having a desired thickness by repeating a plurality of times is widely used. For example, when an SiO ₂ film is formed on a substrate, a source gas containing Si and an oxidizing gas (reactive gas) containing O are used. When a nitride film is formed on the substrate, a nitriding gas is used as a reaction gas instead of an oxidizing gas.
At this time, in order to efficiently react the reaction gas with the raw material component of the raw material gas deposited on the substrate, the plasma is generated by activating the reactive gas using the plasma and reacting the raw material component to form a thin film on the substrate. In many cases, a device is used.

As such a plasma generation device, a plasma generation device comprising a vacuum vessel, an opening provided on a wall surface of the vacuum vessel, and a plate-like high-frequency antenna conductor attached so as to airtightly cover the opening. Known (Patent Document 1).
Since the plasma generator has a structure in which a high-frequency antenna conductor is attached to the opening of the plasma generator, the high-frequency antenna conductor can easily apply a necessary magnetic field to the plasma generation region, thereby easily generating plasma. can do. A thin film can be efficiently formed using this plasma.

WO2009 / 142016A1

  However, when the plasma generating apparatus is used in a thin film forming apparatus using the ALD method, the pressure in the film forming space is higher than that of a conventional CVD apparatus and the like, and in order to adsorb the component of the source gas to the substrate Since the film formation space is configured to be narrow in order to suppress the consumption of the source gas to flow, when attempting to generate plasma by flowing the raw material into the film formation space, it becomes partially narrow rather than near the high-frequency antenna conductor. In some cases, abnormal discharge occurs in the local concave space, and plasma is dominantly and stably generated in this portion. For this reason, plasma is not necessarily generated above the substrate to be deposited in the deposition space, and an efficient thin film may not be formed.

  Accordingly, an object of the present invention is to provide a thin film forming apparatus capable of stably generating plasma on a substrate in order to solve the above problems.

One embodiment of the present invention is a thin film forming apparatus for forming a thin film over a substrate. The device is
A film formation container having a film formation space for forming a thin film on a substrate in a reduced pressure state;
A gas introduction part for introducing a gas used for forming a thin film into the film formation space of the film formation container;
A plasma electrode unit that is provided on an upper part of a mounting table on which the substrate in the film formation space is mounted, and generates plasma using the gas.
The plasma electrode unit includes a rectangular plasma generation electrode plate in which a current flows from one end surface to the other end surface, and a main surface faces the film formation space, and the one end surface of the electrode plate and the different from the other end face, said parallel along the side of both side surfaces of the main surface to the side surface of the electrode plate so as to sandwich the electrode plate, polarities different from each other the ends facing the film-forming space A pair of magnets.

At that time, one of the one end face and the other end face of the electrode plate is a feeding end, and the other is a ground end,
It is preferable that the center of each arrangement position of the magnet is offset toward the feeding end side with respect to the center of the electrode plate in the direction in which the current flows.

Another embodiment of the present invention is a thin film forming apparatus for forming a thin film over a substrate. The device is
A film formation container having a film formation space for forming a thin film on a substrate in a reduced pressure state;
A gas introduction part for introducing a gas used for forming a thin film into the film formation space of the film formation container;
A plasma electrode unit that is provided on an upper part of a mounting table on which the substrate in the film formation space is mounted, and generates plasma using the gas.
The plasma electrode unit includes a plurality of rectangular plasma generation electrode plates in which a current flows from one end surface to the other end surface and a main surface faces the film formation space, and one of the electrode plate surfaces. different from the end surface and the other end face, from the side of the side surface of both sides of the main surface, and a plurality of magnets in parallel along the side surface of the electrode plate so as to sandwich the electrode plate. The plurality of electrode plates are arranged spaced apart on a plane so that the side surfaces thereof face each other, and the plurality of magnets are arranged on the plane between the plurality of arranged electrode plates and outside the side surfaces of the electrode plates on both sides. The end portions of the magnets adjacent to each other facing the film formation space are arranged to have different polarities.

At that time, one of the one end face and the other end face of the electrode plate is a feeding end, and the other is a ground end,
It is preferable that the center of each arrangement position of the magnet is offset toward the feeding end side with respect to the center of the electrode plate in the direction in which the current flows.

  The gas introduction unit introduces a source gas containing a source component for forming the thin film in addition to the gas, and introduces the gas as a reaction gas for reacting the source component deposited on the substrate, thereby providing an atomic layer. The thin film is preferably formed in units.

  In the above-described thin film forming apparatus, plasma can be generated on the upper portion of the substrate more stably than in the prior art.

It is the schematic showing the structure of the thin film forming apparatus which is one Embodiment of this invention. (A) is a top view which shows an example of the plasma electrode part used for the thin film forming apparatus shown in FIG. 1, (b) is a side view of the plasma electrode part shown in (a). It is a top view which shows the other example of the plasma electrode part of this embodiment. (A), (b) is a figure which shows the measurement result of the conventional electrode plate and electron density distribution. (A), (b) is a figure which shows the further another example of the plasma electrode part of this embodiment. It is a figure which shows the further another example of the plasma electrode part of this embodiment.

Hereinafter, the thin film forming apparatus of the present invention will be described in detail.
FIG. 1 is a schematic diagram showing a configuration of a thin film forming apparatus 10 according to an embodiment of the present invention.

  A thin film forming apparatus 10 shown in FIG. 1 is an ALD thin film forming apparatus that forms a thin film on a substrate 20 using generated plasma. The thin film forming apparatus 10 is a system that generates plasma by a magnetic field generated by a current flowing through an electrode plate. This method is different from a method in which plasma is generated by a high voltage generated by resonance of an antenna element such as a monopole antenna. For this reason, it is not necessary to adjust the frequency of the electric power supplied so that the element which produces | generates a plasma may resonate.

(Thin film forming equipment)
Hereinafter, the thin film forming apparatus 10 will be described using an example of forming an Al ₂ O ₃ thin film as a thin film.
The thin film forming apparatus 10 includes a power supply unit 12, a film forming container 14, a gas introduction unit 16, and a gas exhaust unit 18.

The power supply unit 12 includes a high-frequency power source 22, a high-frequency cable 24, a matching box 26, transmission lines 28 and 29, and a plasma electrode unit 30.
The high frequency power supply 22 supplies, for example, high frequency power of several tens of MHz at 10 to 1000 W to the electrode plate 30a (see FIGS. 2A and 2B) of the plasma electrode unit 30. The matching box 26 matches impedance so that the electric power provided through the high-frequency cable 24 is efficiently supplied to the electrode plate 30a of the plasma electrode unit 30. The matching box 26 includes a known matching circuit provided with elements such as a capacitor and an inductor.
The transmission line 28 extending from the matching box 26 is, for example, a copper plate-shaped transmission line having a certain width, and can flow a current of several tens of amperes to the electrode plate 30a. The transmission line 29 extends from the electrode plate 30a and is grounded.

  The plasma electrode unit 30 includes an electrode plate 30a (see FIGS. 2A and 2B) fixed on a partition wall 32, which will be described later, and the first main surface of the electrode plate 30a is in the film forming container 14. It is arranged parallel to the surface of the partition wall 32 toward the film formation space. In the electrode plate 30a of the plasma electrode unit 30, a current flows between the end face to which the transmission line 28 is connected and the end face to which the transmission line 29 is connected. The configuration of the plasma electrode unit 30 will be described later.

  The film formation container 14 has an internal space 38 in the container, and the internal space 38 is divided into an upper space and a lower film formation space 40 by a partition wall 32. The film formation container 14 is formed of a material such as aluminum, for example, and is sealed so that the internal space 38 can be in a reduced pressure state of 1 to 100 Pa. A matching box 26, transmission lines 28 and 29, and a plasma electrode unit 30 are provided in the upper space of the film forming container 14. On the side facing the upper space of the partition wall 32, the plasma electrode unit 30 is fixed. An insulating member 34 for insulating the surrounding partition wall 32 is provided around the plasma electrode portion 30. On the other hand, a dielectric 36 is provided on the side of the partition wall 32 facing the film formation space 40. For the dielectric 36, for example, a quartz plate is used. The reason why the dielectric 36 is provided is to prevent corrosion of the electrode plate 30a and a magnet, which will be described later, due to plasma and to efficiently supply energy to the plasma.

In the film formation space 40 of the film formation container 14, a heater 42, a susceptor 44, and an elevating mechanism 46 are provided.
The heater 42 heats the substrate 20 placed on the susceptor 44 to a predetermined temperature, for example, about 250 ° C.
The susceptor 44 has a mounting table on which the substrate 20 is mounted.
The elevating mechanism 46 moves the susceptor 44 on which the glass substrate 20 is placed together with the heater 42 freely in the film forming space 40. In the film forming process stage, the substrate 20 is set at a predetermined position so as to be close to the plasma electrode unit 30.

The gas introduction unit 16 introduces a source gas and a reaction gas used for forming a thin film into the film formation space 40 of the film formation container 14. The gas introduction unit 16 includes a source gas supply unit 50 and a reaction gas supply unit 51.
The source gas supply unit 50 vaporizes, for example, trimethylaluminum (TMA) and supplies it to the film forming container 14 as a gas. The reactive gas supply unit 51 supplies oxygen gas as a reactive gas to the film forming container 14.

  The gas exhaust unit 18 includes an exhaust pipe extending from a side wall in the film formation space 40, a turbo molecular pump 52, and a dry pump 54. The dry pump 54 roughens the inside of the film formation space 40, and the turbo molecular pump 52 maintains the pressure in the film formation space 40 at a predetermined pressure. The turbo molecular pump 52 and the dry pump 54 are connected by an exhaust pipe.

(Plasma electrode plate)
FIG. 2A is a top view of an example of the plasma electrode unit 30 used in the power supply unit 12. FIG. 2B is a side view of an example of the plasma electrode unit 30 used in the power supply unit 12.
The plasma electrode part 30 is provided on the upper part of the susceptor 44 in the film forming space 40 and generates plasma using a reactive gas. The plasma electrode unit 30 includes a rectangular plasma generation electrode plate (hereinafter referred to as an electrode plate) 30a and a pair of magnets 30b and 30c. In the electrode plate 30a, a current flows from one end face 31a connected to the feeder line 28 toward the other end face 31b connected to the feeder line 29, that is, in the X direction. One first main surface 31 e of the electrode plate 30 a faces the film formation space 40. The feeder line 29 is grounded as shown in FIG.
The pair of magnets 30b and 30c are parallel to the side surfaces 31c and 31d so that the electrode plate 30a is sandwiched between the side surfaces 31c and 31d on both sides, and end portions facing the film formation space 40 have different polarities.
For example, copper, aluminum, or the like is used for the electrode plate 30. As the magnets 30b and 30c, for example, elongated rod-shaped permanent magnets are used.

As shown in FIG. 2B, the end of the magnet 30b facing the film formation space 40 forms an S pole, and the end of the magnet 30c facing the film formation space 40 forms an N pole. In the lower space, a magnetic field is formed from the magnet 30b to the magnet 30c. For this reason, in the space below the electrode plate 30a, plasma P is likely to be generated when power is supplied to the electrode plate 30a. Therefore, unlike the conventional case, abnormal discharge is unlikely to occur in a locally concave space that is partially narrowed. In the unlikely event, abnormal discharge occurs in a locally concave space that is partially narrowed. However, plasma is not maintained in this part. That is, the magnets 30b and 30c form a magnetic field across the width direction of the electrode plate 30a (the horizontal direction in FIG. 2A) so that the plasma P is stably generated in the space below the electrode plate 30a. .
Each of the magnets 30b and 30c only needs to have different polarities at the end portions facing the film formation space 40, and is not limited to a bar magnet. For example, each of the magnet 30b and the magnet 30c may be formed by arranging a plurality of magnets in a line along the side surface of the electrode plate 30a.

  The surface layer of the current flowing through the electrode plate 30a is determined depending on the electrical resistivity of the electrode plate 30a, the frequency of the flowing current, and the magnetic permeability of the electrode plate 30a. For example, when copper or aluminum is used as the material of the electrode plate 30a and the current frequency is several tens of MHz, the depth of the surface layer is about 0.1 mm. Therefore, the thickness of the electrode plate 30a is preferably greater than 0.2 mm in consideration of the current flowing in the surface layer of the first main surface 31e and the second main surface facing the first main surface 31e.

FIG. 3 shows another example of the plasma electrode unit 30 shown in FIG.
The plasma electrode unit 30 shown in FIG. 3 includes an electrode plate 30a and a pair of magnets 30b and 30c, as in the embodiment shown in FIG. In the electrode plate 30 a, current flows from one end surface 31 a connected to the power supply line 28 to the other end surface 31 b connected to the power supply line 29. One first main surface 31 e of the plasma generating electrode plate 30 a faces the film formation space 40. The feeder line 29 is grounded as shown in FIG. As the magnets 30b and 30c, for example, elongated rod-shaped permanent magnets are used.
The plasma electrode part 30 shown in FIG. 3 differs from the plasma electrode part 30 shown in FIG. 2A in that the center of the arrangement position of the magnets 30b and 30c is the electrode plate in the direction of current flow, that is, the X direction. This is offset to the upstream side in the X direction with respect to the center of 30a. The plasma electrode part 30 shown in FIG. 3 is the same as the plasma electrode part 30 shown in FIG.
The reason why the positions of the magnets 30b and 30c of the plasma electrode unit 30 shown in FIG. 3 are offset in this way is to make the density of the generated plasma uniform.

FIGS. 4A and 4B are diagrams for explaining the relationship between the electrode plate and the electron density of the generated plasma.
As shown in FIG. 4A, when the electrode plate 30a in which the magnets 30b and 30c are not arranged on both sides is used, the electron density of plasma generated in the film formation space 40 is as shown in FIG. Value. At this time, 1 kW high-frequency power (13.56 to 60 MHz) is applied to the end surface 31a of the electrode plate 30a, and the end surface 31b is grounded.
That is, as shown in FIG. 4B, the electron density is high on the ground side (the end face 31b side), and the electron density is low on the power feeding side (the end face 31a side). The reason for this is not clear, but the plasma generated based on the magnetic field generated by the current (the plasma derived from the current) is dominant on the ground side, whereas it is generated by the high voltage on the power supply side. This is considered to be because the plasma (plasma derived from voltage) is dominant. This is because, on the high-voltage power supply side, electrons are heated by the electric field, so that sufficient energy cannot be received and it is considered that high-density plasma is difficult to be generated.

Therefore, in the electrode plate 30a, since the plasma density is lowered on the power feeding side, magnets 30b and 30c are provided on the power feeding side to form a magnetic field across the electric field created by the electrode plate 30a. Thereby, the plasma density can be increased on the power supply side.
Therefore, as shown in FIG. 3, by offsetting the arrangement positions of the magnets 30b and 30c to the upstream side in the X direction, that is, the upstream side in the X direction, the plasma density can be made uniform in the X direction.

FIGS. 5A and 5B show still another example of the plasma electrode unit 30 shown in FIG.
FIG. 5 (a), the plasma electrode portion 30 shown in (b) comprises two electrode plates 30a _1, 30a _2, the electrode plates 30a _1, 30a widthwise both sides and the electrode plates 30a ₁ of _2, 30a ₂ Magnets 30b, 30c, and 30d are disposed in the gaps sandwiched between the two. That is, the electrode plates 30a ₁ and 30a ₂ are arranged on a plane so that the side surfaces thereof face each other, and the magnets 30b, 30c and 30d are arranged between the arranged electrode plates 30a ₁ and 30a ₂ and the electrode plate 30a. ₁ , 30a ₂ are arranged on the above-mentioned plane outside the side surfaces on both sides. At that time, the magnets 30b, 30c, 30d are arranged so that the end portions of the magnets 30b, 30c, 30d adjacent to each other toward the film forming space 40 have different polarities.
By configuring the plasma electrode portion 30 in this way, as shown in FIG. 5B, the plasma P is stably generated in a space immediately below the lower portions of the electrode plates 30a ₁ and 30a ₂ . Therefore, in the vicinity of the substrate 20 in the film formation space 40, radicals generated from the reaction gas by the separate plasma P are integrated and become substantially uniform in the width direction of the electrode plates 30 a ₁ and 30 a ₂ , and are deposited on the substrate 20. The raw material components of the raw material gas can be reacted uniformly. Therefore, the thin film can be formed uniformly.

FIG. 6 shows still another example of the plasma electrode unit 30 shown in FIG. As in the plasma electrode unit 30 shown in FIG. 3, the plasma electrode unit 30 shown in FIG. 6 has the center of the arrangement position of each of the magnets 30b, 30c, 30d in the direction of current flow, that is, the electrode plate 30a _{1 in the} X direction. , 30a ₂ is offset upstream of the current. Therefore, the plasma electrode unit 30 shown in FIG. 6 can bring the plasma density close to uniform, similarly to the plasma electrode unit 30 shown in FIG.

Such a thin film forming apparatus 10 can be effectively used as an ALD apparatus.
When the thin film forming apparatus 10 is used as the ALD apparatus, the source gas is supplied from the source gas supply unit 50 in a pulsed form for a short time to cause the source gas to be adsorbed on the substrate 20. At this time, the raw material component of the raw material gas is adsorbed on the substrate 20 in atomic layer units. In such adsorption processing, the raw material components are deposited in layers on the substrate 20 on an atomic basis depending on the chemical properties of the raw material gas. The thin film forming apparatus 10 exhausts the source gas from the film formation space 40 and then supplies the reaction gas from the reaction gas supply unit 51 to the film formation space. At this time, the thin film forming apparatus 10 supplies high-frequency power to the plasma electrode unit 30 to generate plasma in the film formation space 40. In the film forming space 40, a magnetic field is formed by a magnet so as to cross the electrode plate through which the current flows in the width direction of the electrode plate, so that plasma can be generated in the vicinity of the magnetic field directly below the electrode plate. it can. For this reason, abnormal discharge is unlikely to occur in another part of the film formation space 40. Even if plasma due to abnormal discharge is generated in this portion, the plasma is likely to be generated in the vicinity of the magnetic field directly under the electrode plate, and the plasma density is high. Plasma is stably generated in a portion immediately below the inner electrode plate.

  In particular, in a thin film forming apparatus used for ALD, the amount of raw material gas that is adsorbed to the substrate during the formation of the thin film is very small compared to the supplied raw material gas, and most of the raw material gas is exhausted. For this reason, the height of the film formation space 40 is configured to be low in order to suppress wasteful consumption of the source gas. Moreover, the pressure is maintained higher when supplying the reaction gas than in the case of conventional CVD. For this reason, in the film formation space 40, plasma due to abnormal discharge is generated in an unintended place, and plasma may not be generated in the upper part of the substrate 20. However, by forming a magnetic field across the electrode plate in the width direction as in the present embodiment, plasma can be stably generated on the upper portion of the substrate 40 in the film formation space 40 having a low height.

  The thin film forming apparatus of the present invention has been described in detail above. However, the thin film forming apparatus of the present invention is not limited to the above embodiment, and various improvements and modifications may be made without departing from the gist of the present invention. Of course.

10 thin film forming apparatus 12 feed unit 14 deposition container 16 gas inlet 18 gas exhaust unit 20 glass substrate 22 high-frequency power source 24 a high frequency cable 26 matching box 28, 29 transmission lines 30 plasma electrode portions 30a, 30a _1, 30a ₂ electrode plate 30b , 30c, 30d Magnets 31a, 31b End surfaces 31c, 31d Side surfaces 31e First main surface 32 Bulkhead 34 Insulating member 36 Dielectric 38 Internal space 40 Deposition space 42 Heater 44 Susceptor 46 Elevating mechanism 50 Source gas supply unit 51 Reactive gas supply Part 52 Turbo molecular pump 54 Dry pump

Claims (5)

A thin film forming apparatus for forming a thin film on a substrate,
A film formation container having a film formation space for forming a thin film on a substrate in a reduced pressure state;
A gas introduction part for introducing a gas used for forming a thin film into the film formation space of the film formation container;
A plasma electrode unit that is provided on an upper part of a mounting table on which a substrate in the film formation space is mounted, and that generates plasma using the gas;
The plasma electrode unit includes a rectangular plasma generation electrode plate in which a current flows from one end surface to the other end surface, and a main surface faces the film formation space, and the one end surface of the electrode plate and the different from the other end face, said parallel along the side of both side surfaces of the main surface to the side surface of the electrode plate so as to sandwich the electrode plate, polarities different from each other the ends facing the film-forming space A thin film forming apparatus comprising: a pair of magnets having a shape. One of the one end face and the other end face of the electrode plate is a feeding end, and the other is a ground end,
2. The thin film forming apparatus according to claim 1, wherein the center of each of the magnet arrangement positions is offset toward the feeding end with respect to the center of the electrode plate in the direction in which the current flows. A thin film forming apparatus for forming a thin film on a substrate,
A film formation container having a film formation space for forming a thin film on a substrate in a reduced pressure state;
A gas introduction part for introducing a gas used for forming a thin film into the film formation space of the film formation container;
A plasma electrode unit that is provided on an upper part of a mounting table on which a substrate in the film formation space is mounted, and that generates plasma using the gas;
The plasma electrode unit includes a plurality of rectangular plasma generation electrode plates in which a current flows from one end surface to the other end surface and a main surface faces the film formation space, and one of the electrode plate surfaces. different from the end surface and the other end face, from the side of the side surface of both sides of the main surface, and a plurality of magnets in parallel along the side surface of the electrode plate so as to sandwich the electrode plate,
The plurality of electrode plates are arranged spaced apart on a plane so that the side surfaces thereof face each other, and the plurality of magnets are arranged on the plane between the plurality of arranged electrode plates and outside the side surfaces of the electrode plates on both sides. The thin film forming apparatus is characterized in that the end portions of the magnets adjacent to each other facing the film formation space are arranged to have different polarities. One of the one end face and the other end face of the electrode plate is a feeding end, and the other is a ground end,
4. The thin film forming apparatus according to claim 3, wherein a center of each arrangement position of the magnet is offset toward the feeding end with respect to a center of the electrode plate in a direction in which the current flows.   The gas introduction unit introduces a source gas containing a source component for forming the thin film in addition to the gas, and introduces the gas as a reaction gas for reacting the source component deposited on the substrate, thereby providing an atomic layer. The thin film forming apparatus according to claim 1, wherein the thin film is formed in units.

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