JP2008240077A - Ald apparatus and film deposition method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus capable of efficiently depositing a film without necessitating frequent maintenance of a film deposition chamber, in vacuum film deposition by an ALD (atomic layer deposition) method. <P>SOLUTION: The vacuum film deposition is performed by the ALD method which comprises repeating a process for adsorbing a gaseous raw material onto a substrate 4 and a process for reacting a reactive gas with the raw material adsorbed on the substrate 4 while alternately inserting the substrate 4 into a raw material gas adsorption chamber 1 and a reactive gas irradiation chamber 2, wherein the raw material gas adsorption chamber 1 and the reactive gas irradiation chamber 2 are installed to put a substrate exchange chamber 3 between them. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ALD apparatus that performs vacuum film formation by an ALD (Atomic Layer Deposition) method, and a film formation method using the apparatus.

An ALD (Atomic Layer Deposition) method is known as one form of vacuum film formation by a CVD (Chemical Vapor Deposition) method. The ALD method is a method of forming a film by alternately supplying a source gas and a reactive gas to a substrate. For example, when forming a TiN film by the ALD method, TiCl ₄ gas is used as a source gas, NH ₃ gas is used as a reactive gas, and a purge Ar gas is used. First, TiCl ₄ gas is irradiated and adsorbed on a substrate at an appropriate temperature, then purged by introducing Ar gas, switched to NH ₃ gas, reacted with TiCl ₄ molecules adsorbed on the substrate, and again Ar gas The process of purging is repeated for a plurality of times. At this time, a method of irradiating NH ₃ plasma or irradiating radicals generated from NH ₃ is also known in order to reduce residual impurities of the film such as Cl or improve film characteristics. It is also known that metal films such as Ti, Ta, and Cu can be formed using hydrogen plasma or hydrogen radicals.

  Patent Document 1 discloses an ALD method in which a film is formed at a low temperature by repeating a process of adsorbing a metal alcoholate and a process of oxidizing the metal alcoholate adsorbed on a substrate.

JP-A-1-179423

  The conventional ALD apparatus has a problem that a film is also formed on the wall surface of the film forming chamber. This film formation has a film formation speed comparable to the film formation on the substrate, and the deposition proceeds by repeating the film formation process, and the deposited film becomes thick. A thick deposited film peels off and causes a problem of forming particles and forming defects in the film formed on the substrate.

  In particular, when plasma or radical is used as the reactive gas, there is a problem that film formation proceeds strongly in a wide range because of high reactivity, and generation of plasma or radical becomes unstable. In order to suppress such problems, it has been difficult to generate high-density plasma and radicals over a large area, and to control damage caused by plasma.

  Therefore, in the conventional ALD apparatus, maintenance for removing the film deposited on the wall surface of the film forming chamber is frequently required, which is one factor that hinders the improvement of the film forming efficiency.

  An object of the present invention is to provide an apparatus and a method capable of forming a film efficiently without requiring frequent maintenance of a film formation chamber in vacuum film formation by the ALD method.

A first aspect of the present invention is an ALD apparatus for forming a thin film on a substrate,
A source gas adsorption chamber for adsorbing at least one type of source gas to the substrate;
A reactive gas irradiation chamber for irradiating the substrate with at least one kind of reactive gas;
Means for replacing the substrate between the source gas adsorption chamber and the reactive gas irradiation chamber;
It is characterized by having.

  In the ALD apparatus of the present invention, it is preferable that the reactive gas irradiation chamber has a radical source used in remote plasma or a wire used in a CAT-CVD method.

  A second aspect of the present invention uses the first ALD apparatus of the present invention described above, and alternately inserts a single substrate into the source gas adsorption chamber and the reactive gas irradiation chamber, and at least one kind of source material in the source gas adsorption chamber. A film forming method comprising alternately performing a step of adsorbing a gas on a substrate and a step of irradiating the substrate with at least one kind of reactive gas in a reactive gas irradiation chamber.

  In the film forming method of the present invention, it is preferable that the substrate is first placed in a reactive gas irradiation chamber.

  In the present invention, since the film forming chamber is divided for each necessary process, neither the source gas adsorption chamber nor the reactive gas irradiation chamber is formed on the wall surface of the room, Maintenance of the film formation chamber becomes unnecessary. Further, by separating the film formation chamber, it is possible to effectively use highly reactive radicals.

  The present invention divides a conventional film formation chamber into two, one is a source gas adsorption chamber, the other is a reactive gas irradiation chamber, and a substrate is alternately placed in these two chambers to adsorb the source gas to the substrate And the step of reacting the reactive gas with the raw material adsorbed on the substrate.

  The present invention is used, for example, when a thin film such as TiN is vacuum-deposited on a substrate such as Si or glass. Hereinafter, the present invention will be described in detail by taking the case of forming a TiN film as an example.

  FIG. 1 is a schematic configuration diagram of a preferred example of an ALD apparatus according to the present invention, wherein 1 is a source gas adsorption chamber, 2 is a reactive gas irradiation chamber, 3 is a substrate exchange chamber, 4 is a substrate, 5 is a gate valve, 1a , 2a is a substrate holder, and 2b is a W hot wire.

  Tetra (diethylamino) titanium (TDEAT) is introduced into the source gas adsorption chamber 1 as source gas using Ar gas as a carrier gas. The substrate 4 is placed on the substrate holder 1a and controlled to a constant temperature in the range of 150 to 200 ° C.

The reactive gas irradiation chamber 2 is supplied with NH ₃ gas as a reactive gas. In this example, in order to make the reaction more dramatic, the W (tungsten) wire 2b is heated to 1800 ° C. to form NH _x radicals, and the substrate 4 is irradiated. The substrate temperature is controlled to be substantially the same as that of the source gas adsorption chamber 1.

  The source gas adsorption chamber 1 and the reactive gas irradiation chamber 2 are installed with the substrate exchange chamber 3 interposed therebetween, and the substrate 4 is alternately turned into two chambers by a substrate transfer robot (not shown) incorporated in the substrate exchange chamber 3. Inserted into.

The pressure in the source gas adsorption chamber 1 and the reactive gas irradiation chamber 2 is suitably about 10 Pa, for example. The pressure in the substrate exchange chamber 3 is maintained at 10 ⁻⁴ Pa or less. After each step, the source gas adsorption chamber 1 and the reactive gas irradiation chamber 2 are evacuated to 10 ⁻³ Pa or less, and then the gate valve 5 is opened to replace the substrate 4.

  Under the above conditions, it is appropriate that the adsorption time of the source gas is about 0.5 sec to 2 sec and the irradiation time of the reaction gas is about 0.5 sec to 3 sec. It takes about 10 seconds as a substrate replacement time. Therefore, the time required for one cycle is about 20 seconds. Assuming that a film thickness of 1.5 mm can be formed in one cycle, it takes 660 sec to form a film of 50 mm. Since two substrates can be processed in parallel in each of the two chambers, the time is 330 sec per substrate. Therefore, a thin film of about 50 mm has a throughput of about 10 sheets per hour. Since the required film thickness of the barrier film, gate oxide film, etc. of the Cu fine wiring is 50 mm or 10 mm, it becomes a practical device for the application. In order to improve the throughput, the number of rooms can be doubled or tripled.

  The substrate exchange chamber 3 can be an ALD dedicated apparatus by providing a load lock chamber 6 as shown in FIG. Alternatively, as shown in FIG. 3, it is possible to configure a cluster apparatus together with other process modules 7 by providing a new substrate exchange chamber 8.

In the above, an example in which a TiN film is formed by NH _x radicals using TDEAT and a W hot wire has been described. However, the present invention is not limited to this material system. The present invention is also preferably applied to a material system.

  As the reactive gas, preferably plasma or radical is used. For forming plasma, conventionally known parallel plate type, ICP (Inductively Coupled Plasma) type, ECR (Electron Cyclotron Resonance) type, and the like are used. However, when the ion bombardment is large, the molecules previously adsorbed on the substrate are skipped, which is not preferable. A desirable form is so-called remote plasma. More preferably, it is a radical source by RS (Radial Shower) -CVD method or a radical by hot wire of CAT (Catalytic Chemical Vapor Deposition) -CVD method. These radicals do not contain plasma, have no ion bombardment, and have a large amount of radicals. Moreover, since radicals can be supplied uniformly over a wide area, it is optimal for the present invention.

  In ALD, it is important to form the first layer, but in the present invention, the reactive gas irradiation chamber can be used to initialize the surface of the substrate. That is, in the TiN film forming step, the substrate is first cleaned by putting the substrate in a reactive gas irradiation chamber and treating the surface of the substrate with hydrogen radicals. Thereby, the first layer of film can be formed satisfactorily.

It is a schematic block diagram of an example of the ALD apparatus of this invention. It is a plane schematic diagram at the time of configuring the ALD apparatus of the present invention as an ALD dedicated apparatus. It is a plane schematic diagram when a cluster device is configured by combining the ALD device of the present invention with other process modules.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Source gas adsorption chamber 2 Reactive gas irradiation chamber 1a, 2a Substrate holder 2b W hot wire 3 Substrate exchange chamber 4 Substrate 5 Gate valve 6 Load lock chamber 7 Process module other than ALD 8 Substrate exchange chamber

Claims (5)

An ALD apparatus for forming a thin film on a substrate,
A source gas adsorption chamber for adsorbing at least one type of source gas on the substrate;
A reactive gas irradiation chamber for irradiating the substrate with at least one kind of reactive gas;
Means for replacing the substrate between the source gas adsorption chamber and the reactive gas irradiation chamber;
An ALD apparatus comprising:   The ALD apparatus according to claim 1, wherein the reactive gas irradiation chamber includes a radical source used in remote plasma.   The ALD apparatus according to claim 1, wherein the reactive gas irradiation chamber includes a hot wire used in a CAT-CVD method.   Using the ALD apparatus according to any one of claims 1 to 3, one substrate is alternately placed in the source gas adsorption chamber and the reactive gas irradiation chamber, and at least one type of source gas is placed in the source gas adsorption chamber. And a step of irradiating the substrate with at least one kind of reactive gas in the reactive gas irradiation chamber.   The film forming method according to claim 4, wherein the substrate is first placed in a reactive gas irradiation chamber.

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