JP2012190948A - Atomic layer deposition apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an atomic layer deposition apparatus which can form a thin film having higher density by using a plasma ALD method.SOLUTION: The atomic layer deposition apparatus for forming a thin film on a substrate comprises: a film-forming container; a raw material gas supply unit for supplying a raw material gas which is a raw material of the thin film into the film-forming container; a reaction gas supply unit for supplying a reaction gas which reacts with the raw material gas and forms the thin film into the film-forming container; a high-frequency power source for supplying a high-frequency electric current for generating plasma in the inner part of the film-forming container; a control unit for controlling the raw material gas supply unit and the reaction gas supply unit so that the raw material gas and the reaction gas are alternately supplied into the film-forming container, and for controlling timing of which the high-frequency power source supplies the high-frequency electric current; a susceptor having the substrate mounted on the top face thereof; and a magnetic field generation unit for generating a magnetic field above the substrate in a film formation space in the film-forming container, which is provided on the susceptor.

Description

  The present invention relates to an atomic layer deposition apparatus for forming a thin film on a substrate.

  Atomic layer deposition (ALD) is known as a technique for forming a thin film uniformly with excellent step coverage. In the ALD method, two kinds of gases mainly containing an element constituting the thin film to be formed are supplied alternately on the substrate, and the thin film is formed on the substrate in units of atomic layers. In the ALD method, a self-stopping action of the surface reaction is used. The self-stopping action of the surface reaction is an action in which only one layer or several layers of source gas are adsorbed on the substrate surface while the source gas is supplied, and the excess source gas does not contribute to film formation. Therefore, a thin film having a desired film thickness can be formed by repeatedly forming a thin film on the substrate in atomic layer units using the ALD method.

Compared with a general CVD (Chemical Vapor Deposition) method, the ALD method is excellent in step coverage and film thickness controllability. Therefore, it is expected that the ALD method is used for forming a capacitor of a memory element and an insulating film called a “high-k gate”.
In the ALD method, the insulating film can be formed at a temperature of 300 ° C. or lower. Therefore, it is expected that an ALD method is used for forming a gate insulating film of a thin film transistor in a display device using a glass substrate such as a liquid crystal display.

  In the ALD method, water or ozone is used as an oxidizing agent, or plasma generated using oxygen gas or ozone is used. Among these, as a method using plasma, a plasma ALD method in which plasma using an oxidizing gas is generated inside a film forming chamber to form alumina is known (Patent Document 1).

JP 2010-186788 A

When the density of alumina formed by using water or ozone as an oxidant or plasma using an oxidant gas is compared by refractive index, the refractive index of alumina when ozone is used as an oxidant is 1. In contrast, the refractive index of alumina formed using plasma is 1.64. That is, when plasma is used as an oxidizing agent, a high-density thin film can be formed.
However, the refractive index of the alumina sintered body formed by firing aluminum hydroxide in an oxygen atmosphere is 1.76, and the refractive index when using the plasma ALD method capable of forming a thin film at a low temperature is It is still low compared with the case where it is formed by the sintering method. This is because the density of the formed alumina film is lower than that of the sintering method.

  Accordingly, an object of the present invention is to provide an atomic layer deposition apparatus that can form a denser thin film when the plasma ALD method is used.

  In order to solve the above problems, an atomic layer deposition apparatus of the present invention is an atomic layer deposition apparatus for forming a thin film on a substrate, and a film forming container and a raw material gas that is a raw material for the thin film are supplied to the film forming container. A source gas supply unit for supplying, a reaction gas supply unit for supplying a reaction gas that reacts with the source gas to form the thin film into the film formation container, and a high frequency for generating plasma in the film formation container The source gas supply unit and the reaction gas supply unit are controlled so that the source gas and the reaction gas are alternately supplied, and the source of the high-frequency power supplies a high-frequency current. A control unit for controlling the supply timing; a susceptor for placing the substrate on an upper surface; and a magnetic field generation unit that is provided on the susceptor and generates a magnetic field above the substrate in the film formation space of the film formation container; , With The features.

  Moreover, it is preferable that the said magnetic field generation | occurrence | production part is provided in the lower surface of the metal mounting part provided in the said susceptor which mounts the said board | substrate on an upper surface.

  Furthermore, it is preferable that the magnetic field generation unit has a plurality of magnets in a planar shape, and each magnet is provided so that the polarity of the end portion facing upward of the susceptor is different from the adjacent magnet.

  Furthermore, it is preferable that the magnetic field generation unit has a plurality of magnets in a planar shape, and each magnet is provided so that the polarities of the end portions facing the adjacent magnets are different from each other.

  According to the atomic layer deposition apparatus of the present invention, a denser thin film can be formed when the plasma ALD method is used.

It is a schematic block diagram which shows an example of the atomic layer deposition apparatus of 1st Embodiment. It is a figure which shows the example of arrangement | positioning of the several magnet in the atomic layer deposition apparatus of 1st Embodiment. It is a flowchart which shows an example of the atomic layer deposition method of 1st Embodiment. It is a figure which shows the process in which a thin film is formed on a board | substrate. It is a figure which shows the example of arrangement | positioning of the several magnet in the atomic layer deposition apparatus of 2nd Embodiment.

<First Embodiment>
(Configuration of atomic layer deposition system)
First, the configuration of the atomic layer deposition apparatus of this embodiment will be described with reference to FIG. FIG. 1 is a schematic configuration diagram illustrating an example of an atomic layer deposition apparatus according to the present embodiment. The atomic layer deposition apparatus 10 of this embodiment supplies a source gas and a reactive gas alternately, and forms a thin film on the substrate S in units of atomic layers. At that time, plasma can be generated in order to increase the reaction activity. In particular, in the present embodiment, an example in which an alumina thin film is formed by using TMA (Tri-Methyl-Alminum) as a source gas and oxygen gas as a reaction gas will be described, but the present invention is not limited thereto. . For example, ozone gas may be used as the reaction gas.
The atomic layer deposition apparatus 10 according to this embodiment includes a film forming container 20, an exhaust unit 40, a high frequency power supply 50, a control unit 60, a source gas supply unit 70, and a reaction gas supply unit 80.

The film forming container 20 is provided with an upper electrode 22 and a susceptor 30. A lower electrode 32 is provided on the upper surface of the susceptor 30 as a mounting portion. The lower electrode 32 is formed in a flat plate shape and is grounded. The substrate S is supported by lift pins 24 penetrating the susceptor 30 from below the film forming container 20. The lift pins 24 can be moved up and down by an elevating mechanism 26, and the elevating mechanism 26 moves the lift pins 24 downward while the lift pins 24 support the substrate S, whereby the substrate S is placed on the upper surface of the lower electrode 32. Placed.
In addition, a heater 34 is provided inside the susceptor 30, and the temperature of the substrate S can be adjusted by the heater 34.

Further, the susceptor 30 is provided with a plurality of heat-resistant magnets 36 between the lower electrode 32 and the heater 34 in a planar shape. Each magnet 36 is an example of a magnetic field generator. The upper end of each magnet 36 is in contact with the lower surface of the lower electrode 32. In addition, each magnet 36 is provided such that the polarity of the upper end, that is, the end facing upward of the susceptor 30, is different for each adjacent magnet 36. Specifically, as shown in FIG. 2, a magnet 36 with an N pole at the upper end side and a magnet 36 with an S pole at the upper end side are alternately arranged between the lower electrode 32 and the heater 34. Is arranged. In this case, lines of magnetic force 38 due to the magnets 36 adjacent to each other are generated near the upper portion of the substrate S.
In FIG. 2, the magnets 36 are arranged in a line, but a plurality of magnets 36 may be provided. In addition, if the polarity on the upper end side is different for each adjacent magnet 36, the magnets 36 can be arranged in a lattice shape, a ring shape, or the like.
The reason why the magnets 36 are provided in the susceptor 30 is that plasma is generated at a high density above the substrate S by the action of the magnetic field formed above the substrate S by the magnet 36. Thereby, a high-density thin film can be formed.

The upper electrode 22 is provided above the substrate S and is connected to the high frequency power supply 50. Plasma is generated between the upper electrode 22 and the lower electrode 32 by the high-frequency power supply 50 supplying a high-frequency current having a predetermined frequency (for example, 13.56 to 135.6 MHz).
The high frequency power supply 50 is connected to the control unit 60. The timing at which the high frequency power supply 50 supplies the high frequency current to the upper electrode 26 is controlled by the control unit 60.

  The exhaust unit 40 exhausts the source gas, reaction gas, and purge gas supplied into the film forming container 20 through the exhaust pipe 42. The exhaust unit 40 is, for example, a dry pump. The exhaust unit 40 exhausts the film formation container 20 so that the degree of vacuum in the film formation container 20 is maintained at about 1 Pa to 100 Pa even when the source gas, the reaction gas, and the purge gas are supplied into the film formation container 20. Is done.

  The source gas supply unit 70 supplies a source gas such as TMA to the film formation container 20 through a source gas supply port 72 provided in the film formation container 20. The source gas supply unit 70 is connected to the control unit 60. The timing at which the source gas supply unit 70 supplies the source gas is controlled by the control unit 60.

  The reaction gas supply unit 80 supplies a reaction gas such as oxygen to the film formation container 20 via a reaction gas supply port 82 provided in the film formation container 20. The reactive gas supply unit 80 is connected to the control unit 60. The timing at which the reaction gas supply unit 80 supplies the reaction gas is controlled by the control unit 60.

  The control unit 60 independently controls the timing at which the source gas supply unit 70 supplies the source gas, the timing at which the reaction gas supply unit 80 supplies the reaction gas, and the timing at which the high frequency power supply 50 supplies the high frequency current.

Although not shown, each of the source gas supply unit 70 and the reaction gas supply unit 80 is configured to be able to supply a purge gas such as N ₂ gas or Ar gas into the film forming container 20. ing.
The above is the schematic configuration of the atomic layer deposition apparatus 10 of the present embodiment.

(Atomic layer deposition method)
Next, an atomic layer deposition method using the atomic layer deposition apparatus 10 of the present embodiment will be described with reference to FIGS. FIG. 3 is a flowchart showing an example of the atomic layer deposition method of the present embodiment. 4A to 4D are diagrams showing a process of forming a thin film on the substrate S. FIG.

  First, the source gas supply unit 70 supplies source gas into the film forming container 20 (step S101). At a timing controlled by the control unit 60, the source gas is supplied from the source gas supply unit 70 into the film forming container 20. The source gas supply unit 70 supplies a source gas such as TMA into the film forming container 20 for 0.1 seconds, for example. As shown in FIG. 4A, in step S101, the source gas 110 is supplied into the film forming container 20, and the source gas 110 is adsorbed on the substrate S to form the adsorption layer 102.

  Next, the source gas supply unit 70 supplies the purge gas 112 into the film forming container 20 (step S102). The source gas supply unit 70 supplies the purge gas 112 into the film forming container 20 for 0.1 seconds, for example. Further, the exhaust unit 40 exhausts the source gas 110 and the purge gas 112 inside the film forming container 20. The exhaust unit 40 exhausts the source gas 110 and the purge gas 112 inside the film forming container 20 for 2 seconds, for example. As shown in FIG. 4B, in step S <b> 102, the purge gas 112 is supplied into the film formation container 20, and the source gas 110 that is not adsorbed on the substrate S is purged from the film formation container 20.

  Next, the reactive gas supply unit 80 supplies the reactive gas into the film forming container 20 (step S103). At the timing controlled by the control unit 60, the reaction gas is supplied from the reaction gas supply unit 80 into the film forming container 20. The reactive gas supply unit 80 supplies the reactive gas into the film forming container 20 for 1 second, for example. As shown in FIG. 4C, the reaction gas 114 is supplied into the film forming container 20 in step S103.

Further, the high frequency power supply 50 supplies a high frequency current having a predetermined frequency to the upper electrode 26 (step S104). A high frequency current is supplied from the high frequency power supply 50 to the upper electrode 26 at a timing controlled by the control unit 60. The high frequency power supply 50 supplies a high frequency current for 0.2 seconds, for example. At this time, plasma is generated between the upper electrode 22 and the lower electrode 32.
In this case, since the magnetic field generated by the plurality of magnets 36 exists near the upper part of the substrate S, the electron density of the plasma near the upper part of the substrate S increases.

  Note that the timing at which the high-frequency power supply 50 generates the plasma of the reaction gas 114 may be the same as the timing at which the reaction gas supply unit 80 supplies the reaction gas 114 into the film forming container 20.

  Next, the reactive gas supply unit 80 supplies the purge gas 112 into the film forming container 20 (step S106). The reactive gas supply unit 80 supplies the purge gas 112 to the inside of the film forming container 20 for 0.1 seconds, for example. The exhaust unit 40 exhausts the reaction gas 114 and the purge gas 112 inside the film formation container 20. As shown in FIG. 4D, the purge gas 112 is supplied into the film forming container 20 and the reaction gas 114 is purged from the film forming container 20 in step S105.

  The thin film layer 104 for one atomic layer is formed on the substrate S by the steps S101 to S105 described above. Thereafter, by repeating steps S101 to S105 a predetermined number of times, the thin film layer 104 having a desired thickness can be formed.

When the refractive index of alumina and hafnia formed using the atomic layer deposition apparatus 10 of the present embodiment was determined using a spectroscopic ellipsometer, the refractive index of alumina was 1.70, and the refractive index of hafnia was 2.10. Here, when forming hafnia, TEMAH (Tetraethylmethylamino Hafnium) was used as a source gas, and oxygen gas was used as a reaction gas. In addition, this hafnia supplies a source gas with a partial pressure set to 5 Pa for 0.5 seconds when supplying the source gas, and supplies a reaction gas with a partial pressure set to 95 Pa for 1 second when supplying the reaction gas. It is formed by doing.
The environment for obtaining the refractive index will be described. First, the temperature in the film formation container 20 was set to 100 ° C., and the total pressure in the film formation container 20 was set to 1 to 100 Pa. A 2-inch Si wafer was used as the substrate. Further, for the magnet 36, five heat-resistant neodymium magnets having a magnetic strength of 0.5 terrace and a diameter of 1 cm were used. Further, the five magnets were arranged so that the four sides of one magnet whose upper end polarity is the S pole are surrounded by four magnets whose upper end polarity is the N pole.
On the other hand, when alumina and hafnia were formed without using each magnet 36 under the same environment, the refractive index of alumina was 1.64 and the refractive index of hafnia was 1.95. Thereby, when each magnet 36 was used, the high-density thin film was able to be formed.

  As described above, according to the present embodiment, by providing the susceptor 30 with the plurality of magnets 36 that generate a magnetic field in the vicinity of the substrate S, the electron density of plasma in the vicinity of the substrate S can be increased. . Thereby, the denser thin film layer 104 can be formed when the plasma ALD method is used.

  In addition, according to the present embodiment, since plasma can be generated in the vicinity of the substrate S, it is possible to suppress the formation of a thin film on the inner wall portion of the film forming container 20 when the plasma is generated. Can do. Therefore, the cleaning frequency of the inner wall portion of the film forming container 20 can be reduced.

  Furthermore, since the plurality of magnets 36 are provided on the lower surface of the metallic lower electrode 32, the substrate S and each magnet 36 can be brought close to each other via the lower electrode 32. Therefore, it becomes easy to generate a magnetic field above the substrate S by each magnet 36.

Furthermore, since each magnet 36 is provided such that the polarity on the upper end side is different for each adjacent magnet 36, a magnetic field can be generated between the adjacent magnets 36. Therefore, the electron density of plasma in the vicinity of the substrate S can be increased.
At this time, the magnet 36 forms a magnetic field in the film formation space above the substrate S via the metal lower electrode 32, so that the magnetic field approaches a more uniform distribution and generates more uniform plasma. it can.

Second Embodiment
The atomic layer deposition apparatus 10 according to the second embodiment of the present invention will be described below with reference to FIG. The difference from the first embodiment described above is that a plurality of magnets 36 are provided so that the polarities of the end portions facing the adjacent magnets 36 are different from each other. Since other configurations are the same as those of the first embodiment, detailed description thereof is omitted.

As shown in FIG. 5, the magnets 36 are arranged in a row so that one end side in the arrangement direction (left side in the figure) is an S pole and the other end side in the arrangement direction (right side in the figure) is an N pole. In this case, the polarities of the opposite end portions are different between the adjacent magnets 36. In addition, magnetic lines 38 due to the magnets 36 are generated in the vicinity of the upper part of the substrate S.
In FIG. 5, the magnets 36 are arranged in a line, but a plurality of magnets 36 may be provided.

  As described above, according to the present embodiment, the magnets 36 are provided so that the polarities of the ends facing the adjacent magnets 36 are different from each other, so that a magnetic field generated by each magnet 36 is generated above the substrate S. Can be made. For this reason, the electron density of the plasma above the substrate S can be increased.

  Although the atomic layer deposition apparatus of the present invention has been described in detail above, the present invention is not limited to the above embodiment. It goes without saying that various improvements and modifications may be made without departing from the spirit of the present invention.

  For example, although not described in the above embodiment, in order to make the plasma density in the vicinity of the substrate S uniform, the interval between the substrate S and each magnet 36 may be appropriately adjustable. Specifically, the lower electrode 104 may be formed to be exchangeable with another metal plate having a different thickness dimension.

DESCRIPTION OF SYMBOLS 10 Atomic layer deposition apparatus 20 Film-forming container 22 Upper electrode 24 Lift pin 26 Elevating mechanism 28 Lower electrode 30 Susceptor 32 Lower electrode 34 Heater 36 Multiple magnets 40 Exhaust part 42 Exhaust pipe 50 High frequency power supply 60 Control part 70 Source gas supply Unit 72 Source gas supply port 80 Reaction gas supply unit 82 Reaction gas supply port 102 Adsorption layer 104 Thin film layer 110 Source gas 112 Purge gas 114 Reaction gas S Substrate

Claims (4)

An atomic layer deposition apparatus for forming a thin film on a substrate,
A deposition container;
A raw material gas supply unit for supplying a raw material gas which is a raw material of the thin film to the film formation container;
A reaction gas supply unit that supplies a reaction gas that reacts with the source gas to form the thin film into the film formation container;
A high-frequency power source for supplying a high-frequency current to generate plasma in the film forming container;
A control unit that controls the source gas supply unit and the reaction gas supply unit so that the source gas and the reaction gas are alternately supplied, and controls the timing at which the high-frequency power supply supplies a high-frequency current. When,
A susceptor for placing the substrate on an upper surface;
A magnetic field generator provided on the susceptor for generating a magnetic field above the substrate in the film formation space of the film formation container;
An atomic layer deposition apparatus comprising:   2. The atomic layer deposition apparatus according to claim 1, wherein the magnetic field generation unit is provided on a lower surface of a metal mounting unit provided on the susceptor for mounting the substrate on an upper surface.   3. The atomic layer according to claim 1, wherein the magnetic field generation unit includes a plurality of magnets in a planar shape, and each magnet is provided so that a polarity of an end portion facing upward of the susceptor is different from an adjacent magnet. Deposition equipment. 3. The atomic layer deposition apparatus according to claim 1, wherein the magnetic field generation unit includes a plurality of magnets in a planar shape, and each magnet is provided such that the polarities of the end portions facing the adjacent magnets are different from each other.

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