JP6797068B2 - Method for manufacturing titanium carbide-containing thin film by atomic layer deposition method - Google Patents

Description

The present invention relates to a method for producing a titanium carbide-containing thin film by an atomic layer deposition method.

Titanium carbide-containing thin films are used for wiring and electrodes for cutting tools and electronic materials, and their application to, for example, semiconductor memory materials and electrodes for lithium-air batteries is also being studied.

Examples of the method for producing a titanium carbide-containing thin film include a sputtering method, an ion plating method, a MOD (Metal Organic Deposition) method such as a coating pyrolysis method and a solgel method, and a chemical vapor deposition method. Since it has many advantages such as excellent step coverage, suitability for mass production, and hybrid integration, chemical vapor deposition (hereinafter referred to as "Atomic Layer Deposition") including atomic layer deposition (ALD) method is included. The method (sometimes simply referred to as "CVD") is the optimal manufacturing process.

Non-Patent Document 1 and Non-Patent Document 2 disclose tetrakisneopentyltitanium as a titanium source used when a titanium carbide thin film is produced by the MO (Metal Organic) CVD method. However, when a titanium carbide thin film is produced by the MOCVD method using tetrakisneopentyl titanium, the concentration of carbon components in titanium carbide is significantly lower than the theoretical amount, and a high-quality titanium carbide thin film can be produced. could not. When trying to form a film at a high temperature in order to stabilize the quality, tetrakisneopentyl titanium has poor thermal stability, so residual carbon components as organic substances are mixed in the thin film, resulting in a high-quality titanium carbide thin film. There was a problem that it was difficult to form.

Journal of American Chemical Society. 1987, 109, 1579-1580 Journal of American Ceramic Society. 2013, 96, 4, 1060-1062

What is required of a method for producing a thin film containing titanium carbide using a chemical vapor deposition method such as an atomic layer deposition method is that the raw material for thin film formation used does not have spontaneous ignition and a thin film can be safely formed. In addition, the raw material for forming a thin film has good thermal decomposability and / or reactivity with a reactive gas, and is excellent in productivity. Further, it is also required that the obtained titanium carbide-containing thin film contains less residual carbon component as an organic substance and has high quality. Conventionally, there has been no raw material or manufacturing method for forming a titanium carbide-containing thin film that is sufficiently satisfactory in these respects.

As a result of repeated studies, the present inventors have found that a method for producing a titanium carbide-containing thin film by an atomic layer deposition method having a specific step can solve the above problems, and have arrived at the present invention.

That is, the present invention is a method for producing a titanium carbide-containing thin film on a substrate by an atomic layer deposition method, wherein the raw material contains (A) (1,2,3,4,5-pentamethylcyclopentadienyl) trichlorotitanium. A step of introducing gas into the treatment atmosphere and depositing (1,2,3,4,5-pentamethylcyclopentadienyl) trichlorotitanium on the substrate (hereinafter, may be abbreviated as "step (A)"). ); (B) By introducing a reactive gas containing hydrogen into the treatment atmosphere and reacting it with the (1,2,3,4,5-pentamethylcyclopentadienyl) trichlorotitanium deposited on the substrate. The present invention provides a method for producing a titanium carbide-containing thin film, which comprises a step of carbonizing titanium (hereinafter, may be abbreviated as “step (B)”).

According to the present invention, it is possible to produce a high-quality titanium carbide-containing thin film having a small residual carbon component at a low reaction temperature with high productivity.

It is a flowchart which shows an example of the manufacturing method of the titanium carbide-containing thin film which concerns on this invention. It is a schematic diagram which shows an example of the apparatus for ALD method which can be used in the manufacturing method of the titanium carbide-containing thin film which concerns on this invention. It is a schematic diagram which shows another example of the apparatus for ALD method which can be used in the manufacturing method of the titanium carbide-containing thin film which concerns on this invention. It is a schematic diagram which shows another example of the apparatus for ALD method which can be used in the manufacturing method of the titanium carbide-containing thin film which concerns on this invention. It is a schematic diagram which shows another example of the apparatus for ALD method which can be used in the manufacturing method of the titanium carbide-containing thin film which concerns on this invention.

The method for producing a titanium carbide-containing thin film by the atomic layer deposition method of the present invention can use the same procedure as the well-known general atomic layer deposition method, but combines steps (A) and (B) described later. It is a feature of the present invention that this is essential.

In the step (A) in the production method of the present invention, a raw material gas containing (1,2,3,4,5-pentamethylcyclopentadienyl) trichlorotitanium is introduced into the treatment atmosphere, and (1,2) is placed on the substrate. , 3,4,5-Pentamethylcyclopentadienyl) This is a step of depositing trichlorotitanium. Here, the term "deposit" as described herein refers to a concept including the adsorption of (1,2,3,4,5-pentamethylcyclopentadienyl) trichlorotitanium on a substrate. In step (A), a raw material gas containing (1,2,3,4,5-pentamethylcyclopentadienyl) trichlorotitanium is used, and by combining this with step (B), good quality is obtained at a low reaction temperature. It has the effect of being able to produce a titanium carbide-containing thin film. The raw material gas containing (1,2,3,4,5-pentamethylcyclopentadienyl) trichlorotitanium in this step is (1,2,3,4,5-pentamethylcyclopentadienyl) trichlorotitanium. It is preferably contained in an amount of 90% by volume or more, and more preferably 99% by volume or more.

The method for vaporizing (1,2,3,4,5-pentamethylcyclopentadienyl) trichlorotitanium in the step (A) is not particularly limited, and is used in a well-known general atomic layer deposition method. It can be carried out by a method of vaporizing an organometallic compound. For example, it can be vaporized by heating or depressurizing in the raw material container of the ALD method apparatus shown in FIG. The temperature at the time of heating is preferably in the range of 20 ° C. to 200 ° C., more preferably in the range of 50 to 150 ° C. Further, in the step (A), the temperature of the substrate when vaporized (1,2,3,4,5-pentamethylcyclopentadienyl) trichlorotitanium is deposited on the substrate is in the range of 20 to 350 ° C. Preferably, 200 to 300 ° C. is more preferable.

Examples of the material of the substrate in the present invention include silicon; indium arsenic, indium gallium arsenic, silicon oxide, silicon nitride, silicon carbide, aluminum oxide, aluminum nitride, tantalum oxide, tantalum nitride, titanium oxide, titanium nitride, and titanium carbide. , Ceramics such as ruthenium oxide, zirconium oxide, hafnium oxide, lanthanum oxide, gallium nitride; glass; metals such as platinum, ruthenium, aluminum, copper, nickel, cobalt, tungsten, molybdenum and the like. Examples of the shape of the substrate include plate-like, spherical, fibrous, and scaly shapes. The surface of the substrate may be flat or may have a three-dimensional structure such as a trench structure.

In step (B) in the production method of the present invention, a reactive gas containing hydrogen was introduced into the treatment atmosphere and deposited on the substrate (1,2,3,4,5-pentamethylcyclopentadienyl). This is a process of carbonizing titanium by reacting it with trichlorotitanium. By using a reactive gas containing hydrogen in the step (B), there is an effect that a high-quality titanium carbide-containing thin film can be formed at a low temperature.

The reactive gas containing hydrogen in this step may be a gas composed of hydrogen or a mixed gas with a gas such as argon, nitrogen and oxygen. It is preferably a mixed gas of hydrogen and an inert gas typified by argon or nitrogen. The concentration of hydrogen in the mixed gas is preferably in the range of 0.001 to 50% by volume, more preferably 0.01 to 50% by volume, and further preferably 0.01 to 30% by volume.

The method for introducing the reactive gas containing hydrogen into the treatment atmosphere in the step (B) is not particularly limited, and the method is the same as the method for introducing the reactive gas used in the well-known general atomic layer deposition method. However, it is preferable to introduce a reactive gas containing hydrogen vaporized in advance into the treatment atmosphere.

The titanium carbide-containing thin film in the present invention may be a thin film containing 5% by mass or more of titanium carbide, and examples thereof include titanium carbide and an alloy of titanium carbide and molybdenum. Among these, the production method of the present invention is suitable as a method for producing a titanium carbide thin film.

As an example of the method for producing a titanium carbide-containing thin film of the present invention, a method for producing a titanium carbide thin film on a silicon substrate will be described with reference to the flowchart of FIG. Here, the ALD method apparatus shown in FIG. 2 is used.

First, the silicon substrate is installed in the film forming chamber. The method for installing the silicon substrate is not particularly limited, and the substrate may be installed in the film forming chamber by a well-known general method. Further, (1,2,3,4,5-pentamethylcyclopentadienyl) trichlorotitanium is vaporized in the raw material container and introduced into the film forming chamber, and the temperature is 20 to 350 ° C., preferably 100 to 350 ° C. , More preferably 150 to 350 ° C., particularly preferably 200 to 350 ° C., and deposit (adsorb) on a silicon substrate [(A) step].

Next, the trichlorotitanium (1,2,3,4,5-pentamethylcyclopentadienyl) that did not deposit on the silicon substrate is exhausted from the film forming chamber (exhaust step 1). Ideally, the trichlorotitanium that did not deposit on the silicon substrate (1,2,3,4,5-pentamethylcyclopentadienyl) is completely exhausted from the film formation chamber, but not necessarily completely. do not have to. Examples of the exhaust method include a method of purging the inside of the system with an inert gas such as helium and argon, a method of exhausting by depressurizing the inside of the system, and a method of combining these. When the pressure is reduced, the degree of pressure reduction is preferably 0.01 to 300 Pa, more preferably 0.1 to 100 Pa.

Next, a gas containing hydrogen was introduced into the film forming chamber as a reactive gas containing hydrogen, and the trichlorotitanium was deposited on a silicon substrate (1,2,3,4,5-pentamethylcyclopentadienyl). The titanium is carbonized by reacting with [(B) step]. Hydrogen is preferably introduced in the form of a gas, and is preferably a mixed gas with an inert gas such as argon or nitrogen in consideration of safety. The preferred hydrogen concentration in the mixed gas is as described above. The temperature at which heat is applied in this step is 20 to 350 ° C, preferably 100 to 350 ° C, more preferably 150 to 350 ° C, and particularly preferably 200 to 350 ° C. The difference between the substrate temperature in the step (A) and the temperature when heat is applied in the step (B) is preferably in the range of 0 to 20 ° C. in absolute value. This is because, by adjusting within this range, the effect that the titanium carbide-containing thin film is less likely to warp is recognized.

Next, unreacted hydrogen and by-produced gas are exhausted from the film forming chamber (exhaust step 2). Ideally, unreacted hydrogen and by-produced gas are completely exhausted from the reaction chamber, but not necessarily completely. Examples of the exhaust method include a method of purging the inside of the system with an inert gas such as helium and argon, a method of exhausting by depressurizing the inside of the system, and a method of combining these. When the pressure is reduced, the degree of pressure reduction is preferably 0.01 to 300 Pa, more preferably 0.1 to 100 Pa.

The thin film deposition by a series of operations including the above steps (A), exhaust step 1, (B) and exhaust step 2 is set as one cycle, and this film formation cycle is until a titanium carbide-containing thin film having a required film thickness is obtained. It may be repeated multiple times.

Further, energy such as plasma, light, and voltage may be applied to the production method of the present invention. The timing of applying these energies is not particularly limited, and for example, at the time of introducing (1,2,3,4,5-pentamethylcyclopentadienyl) trichlorotitanium in the step (A), in the step (B). It may be during heating, during exhaust in the system in the exhaust step, or during each of the above steps. Of these, when energy is applied by plasma during heating in step (B), a high-quality titanium carbide-containing thin film can be formed at a low temperature, which is particularly preferable.

Further, in the method for producing a thin film of the present invention, when energy is applied by plasma as described above, the reactive gas containing hydrogen may continue to flow into the film forming chamber during all the steps in the production method. Only in the step of forming the titanium carbide-containing thin film, a reactive gas containing hydrogen that has been subjected to plasma treatment may be introduced into the film forming chamber. If the high frequency (hereinafter, also referred to as RF) output is too low, it is difficult to form a film containing a good metal, and if it is too high, the damage to the substrate is large, so 10 to 1500 W is preferable, and 50 to 600 W is more preferable. When the method of applying energy by plasma is adopted in the production method of the present invention, it is preferable because a very high quality titanium carbide-containing thin film can be obtained.

Further, in the production method of the present invention, after thin film deposition, annealing treatment may be performed in an inert atmosphere in order to obtain better electrical characteristics, and if step embedding is required, a reflow step is provided. You may. The temperature in this case is 200 to 1000 ° C, preferably 250 to 500 ° C.

As the apparatus used for producing the titanium carbide-containing thin film according to the present invention, a well-known ALD method apparatus can be used. Specific examples of the apparatus include an apparatus capable of bubbling and supplying raw materials for the atomic layer deposition method as shown in FIG. 2 and an apparatus having a vaporization chamber as shown in FIG. Further, as shown in FIGS. 4 and 5, an apparatus capable of performing plasma treatment on a reactive gas containing hydrogen can be mentioned. Not limited to the single-wafer type apparatus as shown in FIGS. 2 to 5, an apparatus capable of simultaneously processing a large number of sheets using a batch furnace can also be used.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited by the following examples and the like.

[Example 1] Production of titanium carbide thin film (1,2,3,4,5-pentamethylcyclopentadienyl) Using trichlorotitanium as a raw material for the atomic layer deposition method, the following conditions are used using the apparatus shown in FIG. A titanium carbide thin film was produced on a silicon wafer by the ALD method of. The film thickness of the obtained thin film was measured by the X-ray reflectivity method, and the thin film structure and thin film composition were confirmed by the X-ray diffraction method and the X-ray photoelectron spectroscopy. The film thickness was 7.0 nm, and the film composition was found. Was titanium carbide, and the carbon content was 46 atom% (theoretical value 50 atom%). No residual carbon component was detected as an organic substance. The film thickness obtained per cycle was 0.14 nm.

(conditions)
Reaction temperature (silicon wafer temperature): 300 ° C
Reactive gas: Argon gas: 250 sccm (1 atm, 0 ° C) and hydrogen: 50 sccm (1 atm, 0 ° C) mixed gas 50 cycles are repeated with a series of steps (1) to (4) below as one cycle. It was.
(1) Raw material container temperature: 110 ° C., raw material container pressure: 1,2,3,4,5-pentamethylcyclopentadienyl, which is a raw material for the atomic layer deposition method vaporized under the conditions of 0.8 Torr (106 Pa). ) The vapor of trichlorotitanium is introduced into the film forming chamber and deposited on the surface of the silicon wafer at a system pressure of 0.6 Torr (80 Pa) for 10 seconds.
(2) The unreacted raw material is removed by argon purging for 20 seconds.
(3) A reactive gas is introduced and reacted at a system pressure of 0.6 Torr (80 Pa) for 10 seconds. At this time, plasma was formed by applying a high frequency output of 13.56 MHz and 100 W to the reactive gas.
(4) The unreacted raw material is removed by argon purging for 15 seconds.

[Comparative Example 1]
A titanium carbide thin film was produced under the same conditions as in Example 1 except that tetrakisneopentyltitanium was used as a raw material for the atomic layer deposition method.
When the film thickness of the obtained thin film was measured by the X-ray reflectivity method and the thin film structure and thin film composition were confirmed by the X-ray diffraction method and the X-ray photoelectron spectroscopy, the film thickness was 6 nm and the film composition was carbonized. It was titanium and had a carbon content of 40 atom% (theoretical value of 50 atom%). The residual carbon component as an organic substance was detected to be 10 atom% or more. The film thickness obtained per cycle was 0.12 nm.

From the results of Example 1, when the production method of the present invention is used, the residual carbon component as an organic substance is not detected, and a high-quality titanium carbide thin film containing a carbon component close to the theoretical amount can be formed. I understand. On the other hand, in Comparative Example 1, a large amount of residual carbon component as an organic substance was mixed in the thin film, and the thin film contained a carbon content significantly lower than the theoretical amount, resulting in a poor quality titanium carbide thin film. Understand.

Claims (4)

In a method for producing a titanium carbide-containing thin film on a substrate by an atomic layer deposition method,
(A) A raw material gas containing (1,2,3,4,5-pentamethylcyclopentadienyl) trichlorotitanium was introduced into the treatment atmosphere, and (1,2,3,4,5-penta) was placed on the substrate. Methylcyclopentadienyl) Trichlorotitanium deposition process,
(B) Titanium is produced by introducing a reactive gas containing hydrogen into the treatment atmosphere and reacting it with trichlorotitanium (1,2,3,4,5-pentamethylcyclopentadienyl) deposited on the substrate. A method for producing a titanium carbide-containing thin film, which comprises a step of carbonizing. The method for producing a titanium carbide-containing thin film according to claim 1, wherein the temperature of the substrate in the step (B) is in the range of 150 ° C. to 350 ° C. The titanium carbide-containing thin film according to claim 1 or 2, further comprising a step of exhausting the gas in the treatment atmosphere between the step (A) and the step (B) and at least one after the step (B). Manufacturing method. The method for producing a titanium carbide-containing thin film according to any one of claims 1 to 3, wherein the film forming cycle including the step (A) and the step (B) is repeated in this order.

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