Method for producing nickel thin film on a Si substrate by chemical vapor deposition method, and method for producing Ni silicide thin film on Si substrate

Abstract

A method for producing a nickel thin film on a Si substrate by a chemical vapor deposition method, in which the nickel thin film is formed by use of a hydrocarbon-type nickel complex represented by a following formula as a raw material compound, which is a nickel complex in which a cyclopentadienyl group (Cp) or a derivative thereof and a chain or cyclic alkenyl group having 3 to 9 carbon atoms or a derivative thereof are coordinated to nickel and an element other than carbon and hydrogen is not contained in the structure, use of hydrogen as a reaction gas, and use of a film formation pressure of 1 to 150 torr and a film formation temperature of 80 to 250° C. as film formation conditions ##STR00001##
(In the formula, X represents a chain or cyclic alkenyl group having 3 to 9 carbon atoms or a derivative thereof. R.sub.1 to R.sub.5 which are substituent groups of the cyclopentadienyl group represent C.sub.nH.sub.2n+1 and n represents an integer of 0 to 6).

Claims

1. A method for producing a nickel thin film on a Si substrate by a chemical vapor deposition method, comprising the steps of: using a hydrocarbon-type nickel complex represented by a following formula Chem.1 as a raw material compound, which is a nickel complex in which only two ligands, namely a cyclopentadienyl group (Cp) or a derivative of the cyclopentadienyl group (Cp) and an alkenyl group or a derivative of the alkenyl group represented by a formula Chem.2, which is cyclobutenyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, cyclooctenyl, cyclononenyl, or derivatives thereof, are coordinated to nickel and an element other than carbon and hydrogen is not contained in the structure; using hydrogen as a reaction gas, and further using a film formation pressure of 1 to 150 torr and a film formation temperature of 80 to 250° C. as film formation conditions ##STR00004## (In the formula, X represents a chain or cyclic alkenyl group having 3 to 9 carbon atoms or a derivative of the alkenyl group. R.sub.1 to R.sub.5 which are substituent groups of the cyclopentadienyl group represent C.sub.nH.sub.2n+1, and n represents an integer of 0 to 6) ##STR00005##

2. The method for producing a nickel thin film according to claim 1, wherein a Si substrate of which surface is doped with any one of B, P, and As at 10.sup.13 to 10.sup.18 atms/cm.sup.3 is used as the Si substrate.

3. A method for producing a Ni silicide thin film, comprising producing a nickel thin film by the method defined in claim 1, and then performing silicidation of the nickel thin film by heating the substrate at 300 to 600° C. in inert gas or hydrogen atmosphere.

4. A method for producing a Ni silicide thin film, comprising producing a nickel thin film by the method defined in claim 2, and then performing silicidation of the nickel thin film by heating the substrate at 300 to 600° C. in inert gas or hydrogen atmosphere.

5. The method according to claim 1, wherein a nickel thin film is produced directly onto an oxide-film-free Si substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a photographic image of the result of Ni film formation and silicidation according to the presence or absence of an oxide film on a Si substrate (first embodiment).

(2) FIG. 2 is a chart illustrating the result of measuring Ni film formation speed on a Si substrate which was doped with B (second embodiment).

(3) FIG. 3 is a photographic image confirming the silicidation by a heat treatment of the Ni thin film which was formed by the second embodiment.

(4) FIG. 4 is a chart illustrating the result of XPS analysis of a cross section of a thin film after silicidation.

DESCRIPTION OF EMBODIMENTS

(5) Hereinbelow, best modes for carrying out the present invention are described.

(6) First Embodiment: This embodiment was performed to determine the presence or absence of Ni film formation on a Si substrate by use of a hydrocarbon-type Ni complex and silicidation thereof. Here, plural Si substrates with high purity were prepared and each of them was subjected to a film formation test. As for the Si substrate, a Si substrate of which an oxide film has been removed by acid washing and a Si substrate of which an oxide film remains without acid washing were prepared. For acid washing, the substrate was immersed for 5 minutes in dilute hydrofluoric acid (0.5%) to remove an oxide film on the surface.

(7) For film formation test, (η.sup.3-cyclohexenyl)(η.sup.5-cyclopentadienyl)nickel(II) was used as a precursor. Furthermore, a film formation device of cold wall type was used, and the nickel thin film was formed by a CVD method. After the film formation test, SEM measurement of a substrate surface was carried out to evaluate the presence or absence of Ni film formation. Film formation conditions are as described below. Precursor heating temperature: 90° C. Substrate heating temperature: 200° C. Carrier gas: argon, 60 sccm Reaction gas: hydrogen, 100 ccm Pressure: 100 torr Film formation time: 20 minutes

(8) Next, the obtained Ni thin film was subjected to heat treatment for silicidation. Heat treatment conditions include the substrate temperature was set to 500° C. and the substrate was heated in an atmosphere of 10 sccm hydrogen gas+10 sccm argon. The heating time was 10 minutes in total.

(9) FIG. 1 is a scanning electron micrograph of a Ni thin film on each substrate and a thin film after heat treatment. FIG. 1 shows that the Ni film is formed directly on a Si substrate by the precursor and film formation conditions that are applied for this embodiment. FIG. 1 also shows that, by the heat treatment of the film, silicidation progresses and a SiNi thin film is formed on a Si substrate. Meanwhile, the Ni thin film is also formed on a Si substrate with an oxide film (SiO.sub.2). However, no change is seen in the SiNi thin film even after the heat treatment. This is because the SiO.sub.2 layer in a boundary between the Ni thin film and the Si substrate functioned as a barrier layer to inhibit diffusion of Si and silicidation was not progressed.

(10) Second embodiment: A Ni thin film was produced while the surface of a Si substrate has been already doped with B. For the B doping on a substrate, B was doped in an amount of 10.sup.15 atms/cm.sup.3 by an annealing treatment for 30 minutes at 900° C. after ion injection and acid washing was performed in the same manner as above before film formation. For the film formation test of this embodiment, the same precursor as the first embodiment ((η.sup.3-cyclohexenyl)(η.sup.5-cyclopentadienyl)nickel(II)) was used for formation of a Ni film and the film formation speed was evaluated. Film formation conditions are as described below, and the film thickness of a Ni thin film was measured at film formation time of 1 minute, 2 minutes, 5 minutes, and 15 minutes. Precursor heating temperature: 90° C. Substrate heating temperature: 175° C. Carrier gas: argon, 100 sccm Reaction gas: hydrogen, 100 ccm Pressure: 100 torr Film formation time: 1 minute, 2 minutes, 5 minutes, and 15 minutes

(11) FIG. 2 shows the result of the above film formation test. From FIG. 2, incubation time is hardly seen during the film formation process of a Ni thin film on a B-doped Si substrate and the film starts to grow immediately after start of the film formation. Furthermore, the film thickness increases linearly with film formation time. In this embodiment, relatively good film formation speed of 8.2 nm/min is shown.

(12) Furthermore, the substrate of this embodiment on which a Ni thin film is produced with film formation time of 1 minute or 2 minutes was subjected to heat treatment for silicidation of the Ni thin film on a NiSi thin film. The heat treatment conditions included that the substrate temperature was set to 500° C. and the substrate was heated in an atmosphere of 10 sccm hydrogen gas+10 sccm argon. The heating time was 10 minutes in total.

(13) FIG. 3 is a scanning electron micrograph of each Ni thin film before and after heat treatment. All the Ni thin films have a NiSi thin film formed on top of the film by heat treatment. Even when the Ni thin film is thin (i.e., film formation time of 1 minute), homogeneous silicidation with no unevenness was confirmed.

(14) Furthermore, a result of XPS analysis of the NiSi thin film (Ni film formation time of 2 minutes) is shown in FIG. 4. From the NiSi thin film formed in this embodiment, no impurity such as C, N, and O was measured. Furthermore, since the compositional ratio between Ni and Si is approximately 1:1, it was confirmed that a Ni silicide thin film with good quality can be obtained.

INDUSTRIAL APPLICABILITY

(15) The method of the present invention allows a Ni thin film to be formed directly on a Si substrate, and in the method, a high-quality Ni thin film without residual impurities such as C, N, or O can be obtained. Furthermore, the Ni thin film can be directly prepared as a NiSi film by heat treatment. The method of the present invention basically includes a process of producing a thin film with excellent step coverage, i.e., chemical vapor deposition method, and is preferably for production of a stereo electrode with three-dimensional structure of various semiconductor devices.