JP2006269620A - Method and apparatus for wet film formation using ald - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for wet film formation using ALD which can be made compact and reduce cost as a whole by omitting a vacuum device. <P>SOLUTION: This method for wet film formation using ALD includes a step of causing a liquid starting material for film formation using ADL to be in contact with, under atmospheric pressure, the surface of a substrate of which the temperature is raised within a temperature range equal to or lower than a boiling point of the liquid starting material; removing the liquid starting material from the surface of the substrate; causing an oxidant liquid or a nitriding agent liquid for film formation using ALD to be in contact with, under the atmospheric pressure, the surface of the substrate of which the temperature is raised within a temperature range lower than or equal to a boiling point of the oxidant liquid or the nitriding agent liquid; and removing the oxidant liquid from the surface of the substrate. These steps are performed as one cycle to form a thin film of a monoatomic layer on the surface of the substrate, and the cycle is repeated to form a thin film of a multi-atomic layer thereon. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to an ALD wet film forming method and apparatus for forming a thin film by atomic layer deposition (ALD) on a substrate, and more particularly to a TFT (Thin for a flat panel display).
The present invention relates to a wet film forming method and apparatus using ALD used for forming a gate insulating film or an LSI gate insulating film.

With the recent progress in technology for higher integration and higher speed in LSIs, MOSFETs have been miniaturized. As the gate insulating film is made thinner with miniaturization, problems such as an increase in gate leakage current due to tunneling current become obvious. In order to suppress this problem, the gate insulating film using a high dielectric constant material such as HfO ₂ , ZrO ₂ , and Al ₂ O ₃ (hereinafter referred to as a high-k gate insulating film) is made thin. A technique of increasing the physical film thickness while realizing a _two- equivalent film thickness (EOT) has been studied.
In addition, with the improvement of silicon crystallization technology also in TFT. There is a demand for a high-quality gate insulating film with little plasma damage.

  Research has been actively conducted to apply a thin film formation method by ALD to the formation of these insulating films. The film formation method by ALD is plasmaless, and since it is deposited one atomic layer at a time, the step coverage performance and interface characteristics are good, and the film thickness control of an extremely thin insulating film is relatively easy.

  However, the ALD film forming method has a problem that impurities are likely to remain in the formed thin film. As a conventional technique for dealing with this problem, there is an ALD film forming method and a film forming apparatus described in Japanese Patent Laid-Open No. 2003-176109 (Patent Document 1). In Japanese Patent Laid-Open No. 2003-176109, the above problem is caused by an incomplete oxide formation reaction when water vapor is supplied as an oxidant gas. However, it is described that the oxidation reaction can be sufficiently performed by using liquid water.

JP 2003-176109 A

  However, in the ALD film forming apparatus described in Japanese Patent Application Laid-Open No. 2003-176109, the metal raw material for forming a thin film that is supplied first is sent to the reaction vessel in a gas state, and the gas is discharged from the substrate in the sealed reaction vessel. Since the phase reaction is performed, a vacuum device for evacuating the reaction vessel is necessary, and there is a problem that cost increases cannot be avoided.

  An object of the present invention is to provide a wet film forming method and apparatus by ALD which can realize a compact and low cost as a whole without using a vacuum apparatus.

  In order to achieve the above object, the ALD wet film forming method according to the first aspect of the present invention raises a raw material liquid for film formation by atomic layer growth (ALD) in a temperature range below the boiling point of the raw material liquid. Contacting the heated substrate surface under atmospheric pressure or a reduced pressure below atmospheric pressure, removing the raw material liquid from the substrate surface, and oxidizing liquid or nitriding liquid for film formation by the ALD, Contacting the substrate surface heated in a temperature range below the boiling point of the oxidant liquid or nitriding agent liquid under atmospheric pressure or under reduced pressure below atmospheric pressure, and the oxidant liquid or nitriding agent liquid from the substrate surface. The step of removing one cycle is a monoatomic layer thin film formed on the surface of the substrate, and the above cycle is repeated to form a polyatomic layer thin film.

  According to the present invention, the raw material liquid for film formation by ALD is brought into contact with the substrate surface under atmospheric pressure or a reduced pressure below atmospheric pressure, and the oxidant liquid or nitriding agent liquid for film formation by ALD is also added to the raw material. Since the liquid phase reaction is performed by bringing the liquid into contact with the substrate surface in a liquid phase reaction with the substrate surface under a reduced pressure of atmospheric pressure or less, that is, both of them form a thin film by ALD by a liquid phase reaction. Thus, a vacuum apparatus for evacuating the inside of the reaction vessel so that a gas phase reaction can be performed becomes unnecessary, and the entire apparatus can be made compact and the cost can be reduced.

  A wet film-forming apparatus using ALD according to the second aspect of the present invention includes a reaction vessel, a temperature raising member provided in the reaction vessel for raising the temperature of the substrate, and atomic layer growth ( A first raw material liquid contact means for contacting a raw material liquid for film formation by ALD), a raw material liquid removal means for removing the raw material liquid from the surface to be processed of the substrate, and a film by the ALD on the surface to be processed of the substrate. A second raw material liquid contact means for contacting the forming oxidant liquid or nitriding liquid; a second raw material liquid removing means for removing the oxidant liquid or nitriding liquid from the surface to be treated of the substrate; Each operation of the member, the first raw material liquid contact means, the raw material liquid removal means, the second raw material liquid contact means, and the second raw material liquid removal means is performed so as to form a thin film by ALD on the surface to be processed of the substrate. A control unit for controlling, And it is characterized in that there was example.

  According to the present invention, by the control unit, the raw material liquid for film formation by ALD is brought into contact with the substrate surface heated in a temperature range below the boiling point of the raw material liquid under atmospheric pressure or reduced pressure below atmospheric pressure, Subsequently, the raw material liquid is removed from the surface of the substrate, and then the temperature of the oxidizing liquid or nitriding liquid for film formation by the ALD is raised within a temperature range below the boiling point of the oxidizing liquid or nitriding liquid. Is contacted under atmospheric pressure or under reduced pressure below atmospheric pressure, and then a series of steps of removing the oxidant liquid from the substrate surface is taken as one cycle to form a thin film of one atomic layer on the substrate surface, and the cycle is repeated. Thus, it is possible to form a polyatomic thin film. Therefore, the same effect as the first aspect can be obtained with a simple structure.

According to a third aspect of the present invention, in the second aspect, the raw material liquid for film formation by ALD is any one of alkylsilane, alkoxysilane, aminosilane, fluorinated alkoxysilane, and halogen silane. To do.
According to the present invention, the alkyl silane, alkoxy silane, amino silane, fluorinated alkoxy silane, and halogen silane used as the raw material liquid are liquid at room temperature, stable, and easily hydrolyzed. Oxidation or nitridation of the raw material is performed more sufficiently, and an insulating film made of a high-quality oxide or nitride with few impurities can be obtained.

According to a fourth aspect of the present invention, in the second or third aspect, the first raw material liquid contact means is a raw material liquid, the second raw material liquid contact means is an oxidant liquid or a nitriding agent liquid, and the substrate. A liquid film is formed on each of the surfaces to be processed and brought into contact with each other.
Here, the liquid film is formed by dropping the raw material liquid and the oxidizing liquid or nitriding liquid onto the flat surface of the rotating substrate to form a thin liquid film of several microns on the surface of the substrate. It can be easily realized by using a coater. Of course, the liquid may be brought into contact with the substrate surface by spraying or coating.

  According to the present invention, since the liquid phase reaction is performed on the substrate surface by the liquid film, a thin film by ALD can be effectively formed with a small amount of raw material liquid or a small amount of oxide liquid. Therefore, it becomes easy to use expensive raw materials.

  According to a fifth aspect of the present invention, in any one of the second to fourth aspects, the raw material liquid removing unit and the second raw material liquid removing unit blow an inert gas to process the surface of the substrate. It is characterized by drying.

  According to the present invention, since the inert gas is blown to dry the surface to be processed of the substrate, unreacted raw material liquid can be quickly removed and purged. Therefore, it can move to the process of supplying the next raw material immediately.

  According to the present invention, a thin film by ALD is formed by a liquid phase reaction under atmospheric pressure or a reduced pressure below atmospheric pressure, so that the residual amount of impurities in the formed thin film can be reduced, as in the conventional case. A vacuum apparatus for evacuating the inside of the reaction vessel so that a gas phase reaction can be performed becomes unnecessary, so that the entire apparatus can be made compact and the cost can be reduced.

Embodiments of an ALD wet film forming method and apparatus according to the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a schematic block diagram showing an embodiment of a wet film-forming apparatus using ALD according to the present invention, and FIG. 2 is a diagram for explaining the operation of the apparatus.

  The wet film-forming apparatus using ALD according to the present embodiment includes a reaction vessel 1, a temperature raising member 3 provided in the reaction vessel 1 for raising the temperature of the substrate 2, and a surface to be processed 4 of the substrate 2 using ALD. A first raw material liquid contact device 5 for contacting a raw material liquid for film formation, a liquid removing device 6 for removing the raw material liquid from the surface to be processed 4 of the substrate 2, and a surface to be processed 4 of the substrate 2 by ALD. A second raw material liquid contact device 7 for contacting an oxidant liquid for film formation, a liquid removing device 6 for removing the oxidant liquid from the surface 4 to be processed of the substrate 2, the temperature raising member 3, the first A control unit 8 for controlling each operation of the raw material liquid contact device 5, the liquid removing device 6, and the second raw material liquid contact device 7 to form a thin film by ALD on the processing surface 4 of the substrate 2. Yes.

The reaction vessel 1 is used to cause a liquid phase reaction, and in this embodiment, the reaction vessel 1 is configured to cause a liquid phase reaction under an inert gas atmosphere under an atmospheric pressure or a reduced pressure below the atmospheric pressure. Here, the reduced pressure below atmospheric pressure is a reduced pressure at which a liquid phase reaction can be performed, and is a level that does not require a high degree of evacuation necessary for a gas phase reaction. Therefore, no vacuum device is provided. The inert gas atmosphere is realized by flowing nitrogen N ₂ gas from the inlet 12 and flowing it out from the outlet 13.

  The temperature raising member 3 is constituted by a heater 10 built in the substrate set base 9 and is constituted so as to raise the temperature of the substrate 2 in a temperature range below the boiling point of the raw material liquid. In this embodiment, the temperature of the substrate 2 is raised to 50 to 100 ° C. Here, the substrate setting table 9 is configured to be rotatable in the horizontal plane around the center at the same position in a state where the substrate 2 is placed as described later.

  The type of oxidant liquid for film formation by ALD is not limited as long as it can be used for ALD, but it is desirable to use any of alkylsilane, alkoxysilane, aminosilane, fluorinated alkoxysilane, and halogen silane. This is because these raw material liquids are liquid at room temperature, are stable, and easily hydrolyze, so that a liquid phase reaction by contact with the substrate 2 is more easily performed. In this embodiment, the first raw material liquid contact device 5 for bringing the raw material liquid into contact with the substrate 2 drops the raw material liquid onto the flat processed surface 4 of the substrate 2 rotating in a horizontal plane, and the processed surface. A known spin coater mechanism for forming a thin liquid film of several microns in 4 is used.

  As the oxidant liquid for film formation by ALD, pure water is used in this embodiment, but is not limited thereto. In the case of a nitriding agent liquid, ammonia water is mentioned as an example. In the present embodiment, the second raw material liquid contact device 7 for bringing the oxidant liquid into contact with the substrate 2 is configured to form a thin liquid film by using the spin coater mechanism in the same manner as the first raw material liquid contact device 5. Yes.

  The liquid removing device 6 is configured to be able to remove both the raw material liquid and the oxidant liquid from the substrate 2, and blows an inert gas such as nitrogen to dry the surface 4 to be processed of the substrate 2. It is configured to let you. The reaction vessel can be dried to the surface 4 to be processed by simplifying the structure by blowing.

  The control unit 8 brings the raw material liquid for film formation by ALD into contact with the surface of the substrate 2 heated at 50 to 100 ° C., which is a temperature range below the boiling point of the raw material liquid, under the atmospheric pressure. The unreacted raw material liquid is dried and removed from the surface of the substrate by blowing an inert gas, and subsequently the oxidant liquid (pure water) for film formation by ALD is in a temperature range of 50 to 100 below the boiling point of the oxidant liquid. The substrate 2 is brought into contact with the surface of the substrate 2 heated at 0 ° C. under atmospheric pressure, and then the unreacted oxidant liquid is dried and removed from the surface of the substrate 2 by blowing an inert gas as one cycle. A single atomic layer thin film is formed on the surface, and a polyatomic thin film is formed by repeating the cycle.

  Therefore, according to the above-described embodiment, the raw material liquid for film formation by ALD is brought into contact with the surface of the substrate 2 at atmospheric pressure, and the oxidant liquid for film formation by ALD is also used as the raw material liquid of the substrate 2. Since the liquid phase reaction is performed by contacting the substrate surface in a liquid phase reaction with the surface under atmospheric pressure, that is, both of them form a thin film by ALD by the liquid phase reaction under atmospheric pressure. A vacuum apparatus for performing a gas phase reaction by highly evacuating the inside becomes unnecessary, and the entire apparatus can be made compact and the cost can be reduced.

As an example, a case where a SiO ₂ insulating film is formed on the surface to be processed of the silicon single crystal substrate 2 will be described. The entire film formation process was performed in a nitrogen atmosphere.
1. The substrate 2 is heated to 50 to 100 ° C., and liquid silicon tetrachloride (SiCl ₄ ) is applied to the substrate 2 with a spin coater to form a liquid film.
2. An inert gas is blown to dry the substrate surface, and unreacted raw material liquid is removed.
3. The substrate 2 is heated to 50 to 100 ° C., and pure water is applied to the substrate 2 with a spin coater to form a liquid film.
4). An inert gas is blown to dry the substrate surface, and unreacted pure water is removed.
5. The above 1-4 were repeated 50 times.

The thickness of the SiO ₂ insulating film thus formed was 10 nm. This sample was further annealed at 700 ° C. in a nitrogen atmosphere, the formed thin film was densified, and used as a gate insulating film. As a result, electrical properties, interface state density ^{1 × 10 11 cm- 2 eV- 1} , fixed electric density is 5 × ^{10 10} cm- ^2, the breakdown electrolysis was 6 MV / cm. Thus, according to the present embodiment, a high-quality thin film can be obtained at low cost.

  The present invention relates to an ALD wet film forming method and apparatus for forming a thin film by ALD on a substrate, and in particular, wet by ALD used when forming a TFT gate insulating film for a flat panel display or an LSI gate insulating film. It can be used for a film forming method and apparatus.

1 is a schematic block diagram showing an embodiment of an ALD wet film forming apparatus according to the present invention. It is operation | movement explanatory drawing of the same apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reaction container 2 Substrate 3 Temperature raising member 4 Surface to be processed 5 First raw material liquid contact device 6 Liquid removal device 7 Second raw material liquid contact device 8 Control unit

Claims (5)

Contacting a raw material liquid for film formation by atomic layer growth (ALD) with a substrate surface heated in a temperature range below the boiling point of the raw material liquid under atmospheric pressure or reduced pressure below atmospheric pressure;
Removing the raw material liquid from the substrate surface;
The oxidant liquid or nitriding agent liquid for film formation by ALD is brought into contact with the substrate surface heated at a temperature range below the boiling point of the oxidant liquid or nitriding agent liquid under atmospheric pressure or reduced pressure below atmospheric pressure. A process of
Removing the oxidizing liquid or nitriding liquid from the substrate surface;
A one-layer thin film is formed on the substrate surface in one cycle, and a multi-atomic layer thin film is formed by repeating the cycle. A reaction vessel;
A temperature raising member provided in the reaction vessel for raising the temperature of the substrate;
First raw material liquid contact means for bringing a raw material liquid for film formation by atomic layer growth (ALD) into contact with the surface to be processed of the substrate;
Raw material liquid removing means for removing the raw material liquid from the surface to be processed of the substrate;
A second raw material liquid contact means for contacting an oxidant liquid or a nitriding liquid for film formation by the ALD with a surface to be processed of the substrate;
A second raw material liquid removing means for removing the oxidant liquid or nitriding agent liquid from the surface to be treated of the substrate;
The operation of the temperature raising member, the first raw material liquid contact means, the raw material liquid removal means, the second raw material liquid contact means, and the second raw material liquid removal means is performed by forming a thin film by ALD on the surface to be processed of the substrate. A wet film forming apparatus using ALD, comprising:   3. The wet film forming apparatus using ALD according to claim 2, wherein the raw material liquid for forming a film using ALD is any one of alkylsilane, alkoxysilane, aminosilane, fluorinated alkoxysilane, and halogen silane.   4. The method according to claim 2, wherein the first raw material liquid contact means forms a liquid film on the surface to be processed of the substrate, and the second raw material liquid contact means forms a liquid film on the surface to be processed. A wet film-forming apparatus using ALD, characterized in that   5. The raw material liquid removing unit and the second raw material liquid removing unit according to claim 2, wherein the raw material liquid removing unit and the second raw material liquid removing unit are configured to blow an inert gas to dry a surface to be processed of the substrate. A wet deposition system using ALD.

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