Atomic layer deposition apparatus and thin film forming method

An atomic layer deposition apparatus, which forms a thin film on a substrate, includes a first container that defines a first inner space and includes a substrate carrying-in and carrying-out port and a gas introduction port in different positions, the substrate being carried in and out through the substrate carrying-in and carrying-out port, gas being introduced through the gas introduction port to form the thin film on the substrate, a second container that is provided in the first container to define a second inner space separated from the first inner space, the second container including a first opening, a first moving mechanism that moves the second container in a predetermined direction, and a controller that controls the first moving mechanism such that the second container is moved to a first position where the substrate carrying-in and carrying-out port and the first opening are located opposite each other when the substrate is carried in and out, the controller controlling the first moving mechanism such that the second container is moved to a second position where the gas introduction port and the first opening are located opposite each other when the thin film is formed on the substrate.

TECHNICAL FIELD

The present invention relates to an atomic layer deposition (hereinafter also abbreviated to ALD (Atomic Layer Deposition)) apparatus that forms a thin film on a substrate and a thin film forming method for forming the thin film on the substrate by an atomic layer deposition method.

BACKGROUND ART

In the ALD method that is of one of thin-film forming techniques, two kinds of gases composed mostly of elements constituting a film to be formed are alternately supplied onto a deposition target substrate, and the thin film is repeatedly formed plural times in units of atomic layers on the substrate, thereby forming the film having a desired thickness. For example, a source gas containing Si and an oxidation gas containing O are used when a SiO2film is formed on the substrate. A nitridation gas is used instead of the oxidation gas when a nitride film is formed on the substrate.

So-called growth self-stopping action (self-limiting function) is utilized in the ALD method. That is, only a source gas component for one or several layers is adsorbed to a substrate surface while the source gas is supplied, but the excess source gas does not contribute to the growth.

When compared with a general CVD (Chemical Vapor Deposition) method, advantageously the ALD method has both high step coverage and film-thickness controllability. Therefore, the ALD method is expected to be practically applied to the formation of a capacitor for a memory element or an insulating film called “high-k gate.” Additionally, because the insulating film can be formed at a temperature of 300° C. or less in the ALD method, the ALD method is also expected to be applied to the formation of a gate insulating film for a thin-film transistor in a display device such as a liquid crystal display in which a glass substrate is used.

For example, Patent Document 1 describes an ALD apparatus for forming the thin film on the substrate, including a source gas adsorption chamber in which at least one kind of the source gas is adsorbed to the substrate, a reactive gas irradiation chamber in which the substrate is irradiated with at least one kind of a reactive gas, and means for changing the substrate between the source gas adsorption chamber and the reactive gas irradiation chamber.

The apparatus of Patent Document 1 is implemented to provide the apparatus that can efficiently perform the deposition without requiring frequent maintenance of the deposition chamber in vacuum deposition by the ALD method.

PRIOR ART DOCUMENT

Patent Document

DISCLOSURE OF THE INVENTION

Problem to be Solved by the Invention

In the apparatus of Patent Document 1, because the deposition chamber is separated in each necessary process, the deposition is not performed in wall surfaces of both the source gas adsorption chamber and the reactive gas irradiation chamber, the maintenance of the deposition chamber is not required unlike prior art, and a highly-reactive radical can effectively be used. However, the apparatus of Patent Document 1 becomes enlarged and increases in cost. Particularly, an installation area and facility cost increase largely when an eighth-generation glass plate whose one side exceeds 2 m becomes a target substrate on which the thin film is formed.

In order to suppress the cost, an object of the invention is to provide an atomic layer deposition apparatus and a thin film forming method for being able to form the thin film having even film quality on the substrate while having one deposition chamber unlike the configuration of the ALD apparatus of Patent Document 1.

Means for Solving the Problems

An atomic layer deposition apparatus according to a present invention forms a thins film on a substrate. The atomic layer deposition apparatus comprising: a first container that defines a first inner space and includes a substrate carrying-in and carrying-out port and a gas introduction port in different positions, the substrate being carried in and out through the substrate carrying-in and carrying-out port, gas being introduced through the gas introduction port to form the thin film on the substrate; a second container that is provided inside the first container to define a second inner space separated from the first inner space, the second container including a first opening; a first moving mechanism that moves the second container in a predetermined direction; and a controller that controls the first moving mechanism such that the second container is moved to a first position where the substrate carrying-in and carrying-out port and the first opening are located opposite each other when the substrate is carried in and out, the controller controlling the first moving mechanism such that the second container is moved to a second position where the gas introduction port and the first opening are located opposite each other when the thin film is formed on the substrate.

A thin film forming method according to a present invention is used to form a thin film on a substrate by an atomic layer deposition method using a first container that defines a first inner space and a second container that is provided inside the first container and defines a second inner space separated from the first inner space. The thin film forming method comprising: a substrate carrying-in process in which a first opening included in the second container moves to a first position included in the first container to carry in the substrate, the first position being located opposite a substrate carrying-in and carrying-out port through which the substrate is carried in and out; a thin film forming process in which the first opening moves to a second position included in the first container to form the thin film, the second position being located opposite a gas introduction port through which a gas forming the thin film on the substrate is introduced to the second inner space; and a substrate carrying-out process in which the first opening moves to a position located opposite the substrate carrying-in and carrying-out port to carry out the substrate.

Effects of the Invention

According to the atomic layer deposition apparatus and the thin film forming method of the invention, the thin film having the even film quality can be formed on the substrate.

EMBODIMENT FOR CARRYING OUT THE INVENTION

Hereinafter, an atomic layer deposition apparatus and a thin film forming method according to an embodiment of the invention will be described in detail.

<Schematic Configuration of Atomic Layer Deposition Apparatus>

In an atomic layer deposition apparatus10, a source gas such as TMA (Tri-Methyl-Aluminium) and an oxidation gas such as ozone O3are alternately supplied to perform deposition in units of atoms, thereby forming a thin film.

FIG. 1is a sectional view illustrating a schematic configuration of the atomic layer deposition apparatus (hereinafter referred to as an ALD apparatus)10that forms the thin film on a substrate12in a thin film forming process.

The ALD apparatus10mainly includes a first container20, a second container60, and a pressing member80. The first container20is an outside container that defines a first inner space22to maintain a predetermined pressure. The second container60is an inside container provided in the first container20, and the second container60defines a second inner space62to maintain a predetermined pressure. The pressing member80presses the second container60to separate the second inner space62from the first inner space22.

Configurations of the first container20, the second container60, and the pressing member80will be described in detail below.

First, the first container20will be described with reference toFIG. 1.

The first container20is made of a metallic material such as SUS. A gas introduction port through which a N2gas (or inert gas) is introduced to the first inner space22is provided in an upper wall of the first container20. An exhaust port to which an exhaust pipe42is connected is provided in an upper wall of the first container20. The gas in the first inner space22is exhausted to the outside of the first container20by an exhaust unit44such as a turbo molecular pump. Therefore, the first inner space22is maintained at a predetermined pressure in an atmosphere of the introduced N2gas. Oxidation of heaters24and25(described later) can be suppressed by reducing the first inner space22to the predetermined pressure.

The heater24is provided parallel to and above the second container60provided inside the first container20. The heater24heats the substrate12placed in the second container60and the source gas supplied to the second inner space62through the second container60. A wiring and the like of the heater24are extracted to the outside through a through-hole made in an upper portion of the first container20and connected to a power supply (not illustrated).

The heater25is provided parallel to and below the second container60provided inside the first container20. The heater25heats the substrate12placed in the second container60and the source gas supplied to the second inner space62through the second container60. A wiring and the like of the heater25are extracted to the outside of the first container20through a through-hole (not illustrated) and connected to the power supply (not illustrated).

A substrate carrying-in and carrying-out port28is provided in a wall surface26(surface on the right side inFIG. 1) of the first container20to carry in and out the substrate12. A shutter27connected to the outside of the first container20is provided in a portion that is horizontally extended from the substrate carrying-in and carrying-out port28toward the outside of the first container20. Accordingly, when the substrate12is carried in, the shutter27is opened to carry the substrate12in the first container20through the substrate carrying-in and carrying-out port28. When the substrate12is carried out, the shutter27is opened to carry out the substrate12from the first container20through the substrate carrying-in and carrying-out port28.

FIG. 3illustrates the carrying-in and carrying-out state of the substrate12. The carrying-in and carrying-out state of the substrate12inFIG. 3is described later.

In order to introduce the gas that forms the thin film on the substrate to the inside, a gas introduction port29is provided in the wall surface26in which the substrate carrying-in and carrying-out port28is provided. A gas introduction pipe30is connected to the gas introduction port29to introduce the source gas and the oxidation gas to the second inner space62. In the embodiment, two gas introduction pipes30aand30bare connected as illustrated inFIG. 1.

The source gas (for example, organic metal gas such as TMA) and a purge gas (for example, nitrogen gas) are introduced to the second inner space62through the gas introduction pipe30a. The oxidation gas (for example, ozone) and the purge gas (for example, nitrogen gas) are introduced to the second inner space62through the gas introduction pipe30b.

In order to evenly supply the source gas to the substrate12, plural gas introduction ports29are provided at equal intervals in a width direction (direction perpendicular to a paper plane ofFIG. 1) of the substrate12. The gas introduction ports29are provided in a range wider than that in the width direction of the substrate12.

In the embodiment, as illustrated inFIG. 1, the gas introduction ports29are provided immediately above a substrate support portion67(described later).

A through-hole through which an exhaust pipe68(described later) penetrates is provided in the other wall surface (surface on the left side inFIG. 1) of the first container20.

First moving mechanisms36are provided on a bottom surface32of the first container20to vertically move the heater25. The heater25can vertically be moved by adjusting lengths of support mechanisms36aextended from the first moving mechanisms36. Because the heater25supports the second container60, the second container60can be supported in a predetermined position by controlling the lengths of the support mechanisms36aextended from the first moving mechanisms36.

The first moving mechanism36includes a caster37to be able to move in an in-plane direction of the bottom surface32of the first container20.

The bottom surface32of the first container20can be separated from the wall surface and the upper wall of the first container20. Two support mechanisms38aextended downward in the drawings are provided in the bottom surface32of the first container20, and second moving mechanisms38such as hydraulic cylinders are provided in the support mechanisms38a, respectively. The support mechanisms38aof the second moving mechanisms38vertically move the bottom surface32of the first container20, the first moving mechanisms36, the heater25supported by the support mechanisms36aof the first moving mechanisms36, and the second container60supported by the heater25. An O-ring33is provided between the bottom surface32and the wall surface of the first container20, whereby the second moving mechanisms38lift the bottom surface32to close the first inner space22from the outside.

The first moving mechanism36and the second moving mechanism38are connected to a controller100. The controller100controls the first moving mechanisms36and the second moving mechanisms38such that the second container60is located in a predetermined position. The moving mechanisms36and38controlled by the controller100are described in detail later.

According to the embodiment, the substrate carrying-in and carrying-out port28, the gas introduction port29, and the through-hole through which the exhaust pipe68penetrates can separately be made. Therefore, the restriction to the structure of the gas introduction ports29that evenly supply the source gas can be eliminated to form the thin film having the even film quality.

Then the second container60will be described with reference toFIG. 2.FIG. 2(a) is a schematic diagram illustrating the configuration of the second container60.

The second container60is provided in the first container20. The second container60is a canister-shaped container that defines the second inner space62. Preferably the second container60is made of quartz from the viewpoint of a stable material. When a glass substrate is used as the substrate12, because the substrate12is substantially identical to the second container60in the material, advantageously there is no risk that a different component adheres to the substrate12.

The second container60is supported by the support mechanism36aso as to be horizontally located in the first container20. A first opening64is provided at one end of the canister-shaped second container60, and the source gas that forms the thin film on the substrate12flows through the first opening64. In a thin film forming process illustrated inFIG. 1, the first opening64is located opposite the gas introduction port29provided in the wall surface26of the first container20.

A second opening66is provided at an opposite end to the side on which the first opening64is provided, and the gas in the second inner space62flows to the outside of the second inner space62through the second opening66. In the embodiment, two second openings66aand66bare provided as illustrated inFIG. 2(a). The second opening66ais provided immediately above a substrate support portion67(described later).

The gas flowing to the outside of the second inner space62through the second opening66is exhausted by an exhaust unit69such as a vacuum pump through a through-hole made in the left wall surface of the first container20and an exhaust pipe68connected to the through-hole. Therefore, the second inner space62is maintained at a predetermined pressure in an atmosphere of the introduced source gas. The pressure of the second inner space62may be equal to or different from that of the first inner space22.

FIG. 2(b) is a view illustrating a method for carrying in and out the substrate12. The substrate12is placed on a fork portion70at a substrate placing leading end of a conveyance carriage. The shutter27is opened, and the substrate12placed on the fork portion70is carried in and out from the second container60through the substrate carrying-in and carrying-out port28and the first opening64. The substrate carrying-in process and the substrate carrying-out process are described in detail later.

The substrate support portion67is provided in the second container60to place the substrate12thereon. The substrate support portion67is provided in an intermediate position in a height direction of the second inner space62. The substrate support portion67includes a plane that is provided in parallel with the longitudinal direction of the canister-shaped second container60. The plane is used as a substrate placing surface. The side of the first opening64of the substrate support portion67is formed into a comb shape corresponding to the fork portion70at the substrate placing leading end of the conveyance carriage that carries in and out the substrate12.

Thus, the side of the first opening64is formed into the comb shape corresponding to the fork portion70. Therefore, even if the large substrate12is carried in and out from the second inner space62having the low-profile canister shape, the substrate12can be carried in and out while the surface on which the thin film is formed does not come into contact with the inner surface of the second container60.

The source gas passes over the substrate12placed on the substrate support portion67, and part of the source gas is adsorbed to the substrate12. The heated, activated oxidation gas can oxidize the source gas component adsorbed to the substrate12.

A pressing member80will be described below with reference toFIG. 1. The pressing member80presses the second container60in the longitudinal direction (horizontal direction) of the canister-shaped second container60. An O-ring86a, a spacer84, and an O-ring86bare provided in order between the pressing member80and the second container60. A square-shaped bellows82is provided between the pressing member80and the wall surface on the left side of the first container20inFIG. 1. Therefore, the pressing member80can horizontally move. An O-ring90a, a spacer88, and an O-ring90bare provided in order between the second container60and the wall surface26(surface on the right side inFIG. 1) of the first container20. Anti-adhesion plates31and83are provided at an inner wall of the wall surface26near the gas introduction port29and an inner wall of the exhaust pipe68in order to prevent the thin film from adhering to other portions except the substrate on which the thin film should be formed.

The second container60is supported by the first moving mechanism36including the caster37. Therefore, the canister-shaped second container60can move in the longitudinal direction. The pressing member80presses the second container60in the longitudinal direction of the canister-shaped second container60, whereby the second container60is pressed against the first container20with the O-rings86a,86b,90a, and90binterposed therebetween. As a result, the second inner space62is separated from the first inner space22. The pressing member80presses the second container60in the longitudinal direction of the canister-shaped second container60, thereby separating the second inner space62from the first inner space22.

As used herein, separating the second inner space62from the first inner space22means that the pressure of the first inner space22and the pressure of the second inner space62are spatially separated to an extent to which the pressure of the first inner space22and the pressure of the second inner space62can individually be controlled.

Generally, when a space is sealed by the O-ring, the two spaces can more securely be separated from each other with shortening circumference of the O-ring. In the configuration illustrated inFIG. 1, because the second container60is pressed in the longitudinal direction of the canister-shaped second container60, the circumference of the O-ring necessary to separate the second inner space62from the first inner space22can be shortened in association with the canister-shaped second container60.

As described above, the second inner space62of the second container60can more securely be separated from the first inner space22by the configuration in which the second container60is pressed in the longitudinal direction of the canister-shaped second container60. Therefore, a leak of the source gas from the second inner space62to the first inner space22can be suppressed.

The leak of the source gas from the second inner space62to the first inner space22is suppressed to suppress the film formation in the inner surface of the first inner space22by the source gas leaking to the first inner space22, so that resultant particles can be reduced. The mixture of the particles, which exist in the first inner space22, in the second inner space62can be suppressed by separating more securely the second inner space62from the first inner space22. Accordingly, in the embodiment, as illustrated inFIG. 1, the thin film having the evener film quality can be deposited such that the pressing member80presses the second container60in the longitudinal direction of the canister-shaped second container60.

<Schematic Process of Atomic Layer Deposition Method>

An atomic layer deposition method of the embodiment will be described below.

First, the substrate carrying-in process will be described.FIG. 3is a sectional view illustrating a state on the atomic layer deposition apparatus10during the substrate carrying-in process. The first opening64of the second container60is located opposite the substrate carrying-in and carrying-out port28. Hereinafter, the position of the second container60in the state in which the first opening64and the substrate carrying-in and carrying-out port28are located opposite each other is referred to as a first position. That is, during the substrate carrying-in process, the second container60is located in the first position.

The second container60moves to the first position, when the second container60is not located in the first position in carrying in the substrate. The controller100controls the first moving mechanism36to move the second container60.

The shutter27is opened, and the substrate12is carried in the second container60through the shutter27, the substrate carrying-in and carrying-out port28, and the first opening64. As illustrated inFIG. 2(b), the substrate12is carried in while placed on the fork portion70at the substrate placing leading end of the conveyance carriage.

The thin film forming process will be described below.FIG. 1is a sectional view illustrating a state of the atomic layer deposition apparatus10during the thin film forming process. The first opening64of the second container60is located opposite the gas introduction port29. Hereinafter, the position of the second container60in the state in which the first opening64and the gas introduction port29are located opposite each other is referred to as a second position. That is, during the thin film forming process, the second container60is located in the second position.

The second container60moves to the second position, when the second container60is not located in the second position in forming the thin film on the substrate. The controller100controls the first moving mechanism36to move the second container60.

After the second container60moves to the second position, the pressing member80presses the second container60in the longitudinal direction (horizontal direction) of the canister-shaped second container60. Therefore, the second inner space62is separated from the first inner space22. Then the source gas is caused to flow from the gas introduction pipe30to the second inner space62to form the thin film on the substrate12.

The substrate carrying-out process will be described below.FIG. 3is a sectional view illustrating a state of the atomic layer deposition apparatus10during the substrate carrying-out process. The second container60is located in the first position.

When the thin film forming process is ended, the pressing member80presses the second container60against the first container20. The pressing member80moves in the direction (left direction inFIG. 1) in which the pressing member80is separated from the second container60, thereby releasing the press of the second container60.

Then the second container60moves to the first position. The controller100controls the first moving mechanism36to move the second container60.

The shutter27is opened, and the substrate12is carried out from the second container60through the first opening64, the substrate carrying-in and carrying-out port28, and the shutter27. As illustrated inFIG. 2(b), the substrate12is carried out while placed on the fork portion70at the substrate placing leading end of the conveyance carriage.

In the ALD apparatus10, the second inner space62in which the thin film is formed and the first inner space22in which the substrate is carried in and out can be separated from each other by the configuration simpler than ever before, namely, the configuration in which the second container60is moved in the first container20. Therefore, the inner wall surface of the first container20, the inner wall surface of the substrate carrying-in and carrying-out port28, and the inner wall surface of the shutter27are not exposed to the source gas, so that the mixture of the particles can be suppressed in carrying in and out the substrate12.

FIG. 4is a sectional view illustrating a state of the atomic layer deposition apparatus10during a cleaning process. InFIG. 4, the lower portion34and the upper portion40of the first container20are separated from each other.

In order to clean the second container60, the second container60is taken out to the outside of the first container20. In order to take out the second container60to the outside of the first container20, the lower portion34including the bottom surface32of the first container20is moved (that is, to the immediately downward direction) to be separated from the upper portion40, and the lower portion34is moved to the position where the second container60can be taken out to the outside (third position) by the second moving mechanism38. The controller100controls the second moving mechanism38to move the lower portion34.

The position where the second container60can be taken out to the outside means a position where the uppermost position in height direction of the second container60is lower than the lowermost position in height direction of the upper portion40of the first container20. In the cleaning process, preferably the controller100controls the first moving mechanism36such that the length of the support mechanism36ais shortened as much as possible. Therefore, the profile in height direction of the atomic layer deposition apparatus10can be reduced.

As illustrated inFIG. 4, after the upper portion40and the lower portion34of the first container20are separated from each other, the first moving mechanism36is moved in the in-plane direction of the bottom surface32of the first container20, which allows the second container60to be moved from immediately below the upper portion40of the first container. Therefore, the second container60is detached from the first container20.

The second container60provided in the first container20can be easily taken out in the embodiment illustrated inFIG. 4, so that the second container60can easily be cleaned. For example, the cleaning is performed by wet etching.

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