JPH1154459A - Formation of barrier film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a barrier film which forms a superior barrier. SOLUTION: A substrate is carried into a vacuum chamber (S1 ) and heated (S2 ), and the one of a gas containing nitrogen and a gas containing metal of high melting point is introduced (S3 ), and after the one has been evacuated (S4 ), the other is introduced (S5 ), and then the other is evacuated (S6 ). This process is repeated a plurality times (S9 ), and thereby CVD reaction occurs between the one adsorbed onto the substrate surface and the other introduced afterwards, and a barrier film grows conformably in a contact hole, and the barrier film with good step coverage can be thus obtained. A purge gas is introduced at each CVD reaction (S7 ) and evacuated (S8 ) to exchange by-product gases and unconverted gas adsorbed onto the substrate and the vacuum chamber for the purge gas, and a purer barrier film can be thus obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a technical field of forming a barrier film, and more particularly, to a technique of forming a barrier film by using a CVD method.

[0002]

2. Description of the Related Art As a material used for thin film wiring in a semiconductor device, aluminum is frequently used because of its low resistance and easy manufacture, and an Al thin film (Cu or Si is formed on a substrate surface by a sputtering method. (Including an added thin film), and patterning is performed using the resist film as a mask to form an Al wiring thin film having a desired shape.

However, if an Al thin film is formed directly on the surface of the silicon substrate exposed under the bottom of the contact hole, aluminum and silicon react with each other, which may cause poor connection of the contact hole.

Therefore, measures have been taken in the prior art,
If the silicon substrate is exposed at the bottom of the contact hole,
After the barrier film is once formed on the entire surface, an Al thin film is formed. The Al thin film does not directly contact the silicon substrate surface, so that aluminum does not react with silicon.

A conventional barrier film forming method will be described. Generally, a sputtering apparatus 103 as shown in FIG.
Is used, a substrate 150 to be formed is loaded into the vacuum chamber 120, placed on the substrate holder 121 on the bottom wall, and the inside of the vacuum chamber 120 is evacuated. Then, a sputtering gas plasma is generated, and a target 122 disposed opposite to the substrate 150 is sputtered, and metal particles or metal nitride particles protruding from the target 122 are attached to the surface of the substrate 150, and a high melting point is applied to the surface of the substrate 150. A metal nitride thin film is formed, and the thin film constitutes a barrier film.

In such a sputtering apparatus 103, if the magnet 123 is arranged on the back surface of the target 122, the plasma density on the surface of the target 122 increases, and a barrier film can be formed at a very high deposition rate. At present, the barrier film manufacturing method has become mainstream.

However, the barrier film formed by the sputtering method has a problem that the step coverage is poor. In particular, as shown in FIG.
When a contact hole 160 having a high aspect ratio is formed in the silicon thermal oxide film 152 on the surface of the
When barrier film is formed by sputtering method,
As shown in (b), the thickness a of the barrier film 153 formed on the surface of the silicon thermal oxide film 152 tends to be large, and the thickness b of the barrier film 153 formed below the bottom of the contact hole 160 tends to be small. On the other hand, there is a problem that the barrier property cannot be obtained in the surface of the substrate 151, especially in the contact hole 160 where the film thickness b is small.

In addition, due to the relative positional relationship between the contact hole 160 and the target 122, near the periphery of the bottom surface of the contact hole 160, the thick portion m of the barrier film 153 (the side far from the target 122) and the thin portion n
(The side closer to the target 122)
As shown in (c), when an Al thin film 154 is formed on the surface and heat treatment is performed, aluminum atoms penetrate into the substrate 151 from the thin portion n of the barrier film 153 and spikes p are generated. Formed, causing a problem of poor connection.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned disadvantages of the prior art, and has as its object to provide a technique capable of forming a barrier film having excellent barrier properties. . Another object of the present invention is to provide a technique capable of forming a metal nitride thin film having good step coverage.

[0010]

According to a first aspect of the present invention, a substrate is loaded into a vacuum chamber.
After raising the temperature to a predetermined temperature, a nitrogen-containing gas and a high-melting metal gas are introduced, and a barrier film forming method for forming a nitride thin film of a high-melting metal on the substrate, wherein the nitrogen-containing gas and The step of introducing one of the high melting point metal gases, evacuating the one gas, introducing the other gas, and evacuating the other gas is repeated a plurality of times. I do.

According to the structure of the present invention, when one of the nitrogen-containing gas and the high-melting-point metal gas is introduced and evacuated, the gas is adsorbed on the substrate surface,
Since the other gas is introduced in that state, the nitrogen-containing gas and the high-melting-point metal gas become C
VD reaction.

Since the amount of adsorbed gas is substantially the same on the surface of the insulating thin film, the wall surface of the contact hole, and the surface of the substrate, a nitride thin film of a refractory metal grows conformally in the contact hole provided on the substrate. Thus, a barrier film having good step coverage can be obtained.

[0013] The CVD reaction stops when one of the adsorbed gases is consumed, but the amount of adsorbed gas can be controlled to about one molecular layer by keeping the substrate temperature at an appropriate level. In the step (1), the CVD reaction proceeds only slightly, and the nitride thin film of the refractory metal is laminated in one or several molecular layers, so that a stoichiometric barrier film can be obtained.

In this case, after the other gas is introduced and the CVD reaction is performed, the gas is evacuated once, so that the by-product gas and the unreacted gas are removed, the contamination with impurities is small, and the purity is high. Can be obtained.

In the method of forming a barrier film according to the first aspect, when forming the nitride thin film of the refractory metal as in the second aspect of the invention, the other gas is evacuated, and then the second gas is evacuated. Before introducing one of the gases, a purge gas can be introduced and the purge gas can be evacuated.

According to the second aspect of the present invention, after the CVD reaction is performed, a purge gas is introduced and vacuum evacuation is performed, and the by-product gas and the unreacted gas adsorbed on the substrate surface and the inner wall of the vacuum chamber are purged. Will be replaced with the next CVD
When the reaction is performed, the surface of the substrate becomes clean, and it becomes possible to obtain a barrier film with higher purity.

As the purge gas, an inert gas such as N ₂ gas and a reducing gas such as H ₂ gas can be used in addition to a rare gas such as Ar gas and He gas.

In general, when performing a CVD reaction,
When the substrate temperature is high or low, the barrier properties of the formed barrier film deteriorate. According to the method of forming a barrier film according to any one of claims 1 and 2, according to an experiment, the substrate temperature when forming a nitride thin film of a high melting point metal is set to a range of 200 ° C. or more and 800 ° C. or less. By doing so, a barrier film having good barrier properties has been obtained.

Further, any one of claims 1 to 3
In the barrier film forming method according to the above aspect, as in the invention according to claim 4, before forming the nitride thin film of the high melting point metal, the introduction of the high melting point metal gas and the evacuation are performed, A high melting point metal thin film can be formed at an interface between the surface of the high melting point metal nitride thin film and the substrate surface. In this case, since the high melting point metal thin film comes into contact with the substrate, the substrate and the high melting point metal react by heat treatment when forming the Al thin film, and the resistance value of the contact hole decreases.

Further, any one of claims 1 to 4
In the barrier film forming method according to the above aspect, after forming the nitride thin film of the high melting point metal, the introduction of the high melting point metal gas and the evacuation are performed to form the high melting point metal. A high melting point metal thin film can be formed on the surface of the metal nitride thin film. In this case, the wettability of the barrier film surface is improved and the flow of the Al thin film is facilitated, so that even the contact hole having a high aspect ratio can be filled up to the bottom with the Al thin film.

Further, as in the invention according to claim 6, after forming the nitride thin film of the high melting point metal, a gas (H ₂ gas, SiH ₄ gas or the like) that reduces the high melting point metal gas and the same gas. The so-called blanket CVD method of depositing a high melting point metal on the surface of the nitride thin film of the high melting point metal to fill a contact hole or to form a wiring outside the hole can also be performed.

The high melting point metal gas described above includes:
As in the invention according to claim 7, Ti, Ta,
A gas containing any kind of high melting point metal of W can be used.

Further, the gas containing any one of the high melting point metals of Ti, Ta and W includes a fluoride gas, a chloride gas, a bromide gas, an iodide gas, and the like. Either one kind of alkoxide gas or organic substance gas, or two or more kinds of gases can be used.

On the other hand, the nitrogen-containing gas includes N ₂ gas, N ₂ H ₄ gas, NH ₃ gas, and N ₂ gas.
Any type of ₂ O gas or a mixture of two or more types of gas can be used.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, reference numeral 3 denotes an example of a CVD apparatus which can be used in the barrier film forming method of the present invention.
An Al thin film forming chamber 12 and a process chamber (vacuum chamber) 20 are arranged.

A hot plate 21 is provided on the bottom wall of the process chamber 20. A substrate is arranged on the hot plate 21. When the hot plate 21 is energized, the substrate can be heated to a desired temperature. ing.

The process chamber 20 has a vacuum exhaust system 2
6 and the gas introduction system 22 are connected, and the evacuation system 26
By operating a high vacuum pump provided in the process chamber, the inside of the process chamber 20 can be brought into a high vacuum state. When the gas introduction system 22 is used in a state in which the exhaust is stopped, a desired type of gas is controlled in the process chamber 20 by pressure control. It is configured so that it can be introduced in a state where it has been installed.

The process chamber 20 contains a reservoir tank 25.
The reservoir tank 25 is connected to a low-vacuum pump provided in a vacuum exhaust system 26 so that the inside of the reservoir tank 25 can be evacuated to a predetermined pressure or less from a relatively high pressure state. I have.

The inside of the reservoir tank 25 is configured to be connectable to the inside of the process chamber 20. When the process chamber 20 is in a relatively high pressure state, the low vacuum pump 25 is operated in the connected state. Then, the inside of the process chamber 20 can be evacuated to a predetermined pressure or less via the inside of the reservoir tank 25.

The method of forming a barrier film according to the present invention will be described. A substrate transfer robot 15 is provided in the transfer chamber 10. First, a substrate on which a film is to be formed is mounted in a substrate transfer chamber (not shown), and is transferred into the pretreatment chamber 11 by the substrate transfer robot 15.

In the pretreatment chamber 11, the substrate surface is cleaned by irradiating the substrate surface with argon gas plasma, baked by an infrared lamp, the surface is cleaned, and then moved through the transfer chamber 10 without being exposed to the atmosphere. Then, it was carried into the process chamber 20 (substrate loading).

A first example of the method of the present invention will be described with reference to the flowchart of FIG. After substrate loading
(Step S ₁ ) As shown in FIG. 1, the substrate 5 carried into the process chamber 20 was placed on a hot plate 21 whose temperature was controlled at 300 ° C., and the temperature was controlled. The inside of the process chamber 20 is evacuated by the evacuation system 26 (step S ₂ ).

When the temperature of the substrate 5 reaches 300 ° C., the pressure in the process chamber 20 is 2 × 10 ⁻⁵ Torr,
While maintaining the temperature at 300 ° C., the vacuum evacuation is stopped, and an NH ₃ gas (nitrogen-containing gas) is introduced by the gas introduction system 22, and the pressure in the process chamber 20 is reduced to 3 × 10 ^-1 Torr.
Filled with ₃ gases.

This state is maintained for 2 seconds, and after the NH ₃ gas is adsorbed on the surface of the substrate 5 (step S ₃ ), the reservoir tank 25 previously evacuated is connected to the process chamber 20, and The pressure inside the process chamber 20 was rapidly reduced, and the inside of the process chamber 20 was evacuated through the reservoir tank 25 by the low vacuum pump of the vacuum exhaust system 26.

When the inside of the process chamber 20 has decreased to a predetermined pressure, the reservoir tank 25 is separated, and the inside of the process chamber 20 is directly evacuated by the high vacuum pump of the evacuation system 26. 3x
The pressure decreased from 10 ^-1 Torr to 5 × 10 ^-5 Torr in about 10 seconds (step S ₄ ).

Under that pressure, T
An iCl ₄ gas (a metal gas containing a high melting point) was introduced, and the inside of the process chamber 20 was filled with a TiCl ₄ gas at a pressure of 5 × 10 ⁻¹ Torr.

After maintaining this state for 2 seconds, the NH ₃ gas adsorbed on the surface of the substrate 5 reacts with the TiCl ₄ gas to form a TiN thin film (a high melting point metal nitride thin film) on the surface of the substrate 5 ( step S _5), evacuating to vacuum in the same manner as in step S _4, was evacuated by-product gas and unreacted gas (step S _6).

Thereafter, Ar gas is supplied by the gas introduction system 22.
(Purge gas) and a pressure of 5 × 1 in the process chamber 20.
The gas is filled with Ar gas of 0 ^-1 Torr, and the state is maintained for 2 seconds (Step S ₇ ), and the unreacted gas and by-product gas adsorbed on the surface of the substrate 5 and the wall surface of the process chamber 20 are converted into Ar gas. is replaced, then evacuated in the same manner as in step S ₄ (step S _8).

After exhausting the Ar gas, the flow returns to the NH ₃ gas introduction step again (step S ₉ ), and from the introduction of the NH ₃ gas, the Ar ₃ gas is introduced.
The processing up to the exhaust of the gas (Step S ₃ ~S _8), a total of 50
Repeated times.

After exhausting the last Ar gas (Step S ₈ ), the substrate 5 was unloaded from the process chamber 20 (Step S ₁₀ ), and was taken out of the CVD apparatus 3 from a substrate unloading chamber (not shown).

FIG. 7 schematically shows the result of observing the cross section of the substrate 5 using an SEM. The substrate 5 has a silicon substrate 51 and a silicon thermal oxide film 52 formed on the surface of the silicon substrate 51. The silicon thermal oxide film 52 has a contact hole 60 in which the silicon substrate 51 is exposed at the bottom. Is provided.

According to the observation result, the silicon thermal oxide film 52
A TiN thin film is formed as a barrier film 53 on the surface and the bottom of the contact hole 60, and a silicon thermal oxide film 52 is formed.
The thickness a of the surface and the thickness b of the bottom of the contact hole 60 are:
Both were 200 ° and the step coverage was good. Also, the film thickness c is formed on the wall surface of the contact hole 60.
A TiN thin film having a thickness of 200 °
It was confirmed that No. 3 was growing conformally.

When the composition of the barrier film 53 was analyzed using an Auger electron spectrometer, TiN _x , x = 0.9-1.1.
And it was confirmed that the thin film was almost stoichiometric. In the analysis results, impurities such as Cl were not detected.

Next, a substrate in which a large number of contact holes having a diameter of 0.5 μm or 0.7 μm are formed on a silicon thermal oxide film having a thickness of 1.0 μm and the number of repetitions is set to 20 is shown in FIG. A barrier film made of a TiN thin film was formed in the same procedure as described above.

After the formation of the barrier film, the film is transferred through the transfer chamber 10 into the low-temperature Al thin film formation chamber 12 without being exposed to the atmosphere.
After the first low-temperature Al thin film is formed by the long throw sputtering (LTS) method, the high-temperature Al thin film forming chamber 13 is formed.
After forming a second layer of Al thin film at 450 ° C. while flowing at 450 ° C. (so-called two-step flow method), the first
It was cooled to 00 ° C. or lower and taken out.

FIG. 8 schematically shows the result of observing the cross section of the substrate. On the surface of the silicon thermal oxide film 52 and on the bottom surface of the contact hole 60 ', a TiN thin film having a thickness of 70 [deg.] Was formed conformally, and a barrier film 53' having good step coverage was obtained.

Two layers of Al formed on the surface of the barrier film 53 '
-Cu alloy thin films 54 ₁ and 54 ₂ have a total thickness of 8000 °, and have a thickness of 0.7 μm in contact hole 60 ′.
The thin film was filled to the bottom. In the case of the 0.5 μm contact hole 60 ′, voids were observed in some of them. In the case of a contact hole having a thickness of 0.5 μm, it was found that it is necessary to use a barrier film forming method of a third example of the present invention described later. Note that no spike due to aluminum diffusion was observed in the silicon substrate 51, confirming that the barrier film 53 ′ has excellent barrier properties.

Next, the relationship between the substrate temperature and the barrier property during the formation of the barrier film is shown in FIG. Other conditions except for changing the substrate temperature are the same as those in the above embodiment. The horizontal axis T in FIG. 11 is the substrate temperature, and the vertical axis F (%) is F = the number of contact holes with no leakage / the total number of contact holes.

When the substrate temperature is lower than 200 ° C. or 80
When the temperature exceeds 0 ° C., the value of F of the obtained barrier film is lowered. When a barrier film composed of a TiN thin film is formed, a temperature range of 300 ° C. or more and 800 ° C. or less is suitable. I understand.

In the first example, the TiCl ₄ gas was introduced after the introduction of the NH ₃ gas. However, as shown in the flowchart of FIG. 3, the order of introduction of the NH ₃ gas and the TiCl ₄ gas was changed. Is also good.

Referring to the flowchart of FIG. 3, after the substrate is loaded and the temperature is adjusted (steps T ₁ and T ₂ ),
First, introduction and exhaustion of TiCl ₄ gas are performed (steps T ₃ and T ₄ ). First, TiCl ₄ gas is adsorbed on the substrate surface, and NH ₃ gas is introduced in that state (step T ₅ ).
After performing a CVD reaction to deposit TiN on the substrate surface, and then performing vacuum evacuation (step T ₆ ), exhausting by-product gas and unreacted gas, and then introducing Ar gas as a purge gas (step T _7). ), The adsorption gas is exchanged for a purge gas.

After the purge gas is evacuated (step T ₈ ), the process returns to the step of introducing TiCl ₄ (step T ₉ ), and the steps from the introduction of TiCl ₄ to the exhaust of Ar gas are repeated a desired number of times. When the substrate is unloaded (step T ₁₀ ), a barrier film made of a TiN thin film can be formed on the substrate surface, similarly to the process shown in the flowchart of FIG.

After a barrier film was formed on the substrate surface according to the flow chart of FIG. 3, the cross section was observed. As a result, the barrier film was conformally grown in the contact hole as shown in FIG. And the step coverage was good.

Next, the process of the second example of the present invention will be described.
FIG. 4 shows a part of the process of the second example,
FIG. 4A shows a process A for forming a Ti thin film, and FIG.
This is a step B of forming an N thin film.

Step A will be described.
After the substrate is placed on the upper side and the vacuum evacuation is performed, introduction of TiCl ₄ gas and vacuum evacuation are performed (steps A ₁ and A ₂ ), then introduction of H ₂ gas, which is a reducing purge gas, and vacuum evacuation are performed. (Steps A ₃ and A ₄ ), and return to the step of introducing TiCl ₄ gas (Step A ₅ ). If TiCl ₄ is repeated a desired number evacuation of the H ₂ gas (steps A ₁ to A ₄₎ from the introduction of the gas, it is possible to form a Ti film on a substrate.

Step B will be described. NH ₄ gas is introduced and evacuated (steps B ₁ and B ₂ ), TiCl ₄ gas is introduced and evacuated (steps B ₃ and B ₄ ), Ar gas is introduced and evacuated. (Steps B ₅ and B ₆ ) are sequentially performed, and the process returns to the NH ₄ gas introduction step (step B ₇ ). By repeating the steps from the introduction of the NH ₄ gas to the evacuation of the H ₂ gas (steps B _{1 to} B ₆ ) a desired number of times, a TiN thin film can be formed on the substrate.

Using the steps shown in FIGS. 4A and 4B,
As shown in the flowchart of FIG. 5, after performing the substrate loading and the temperature control at 300 ° C. (Steps U ₁ and U ₂ ), the process A (5 repetitions) and the process B (15 repetitions) are performed. A Ti thin film and a TiN film were formed in this order (steps U ₃ and U ₄ ) and unloaded (step U ₅ ). In this second example, as shown in FIG.
The barrier film 63 was composed of the TiN thin film 56 formed on the surface of the i thin film 55.

When an Al thin film was formed on the surface of the barrier film 63 by a two-step flow method, the inside of the contact hole 61 of 0.7 μm could be filled to the bottom. The barrier property of the barrier film 63 was equivalent to that of the first example.

The resistance value of the contact hole 60 of the first example and the resistance value of the contact hole 61 of the second example filled with an Al thin film were compared.
Since the thin film 55 is in contact with the silicon substrate 51, the silicon substrate 5 is affected by the heat treatment when forming the Al thin film.
The interface between 1 and the Ti thin film 55 was silicided, and the resistance value of the contact hole 61 of the second example was lower than that of the contact hole 60 of the first example.

In this second example, after the substrate was heated, before introducing the TiCl ₄ gas, NH ₃ gas was introduced and evacuated, and then before introducing Ar gas and evacuating. It is confirmed that when a treatment step is provided and one or two pretreatment steps are performed, the occurrence of encroachment can be suppressed while keeping the step coverage, composition, and barrier properties equal to those in the first example. Was.

Next, the process of the third embodiment of the present invention will be described with reference to FIG. After the substrate was loaded and the substrate was heated to 300 ° C. (Steps V ₁ and V ₂ ), Steps A, B and A were performed (Steps V ₃ , V ₄ and V ₅ ), and the substrate was unloaded. (Step V ₆ ). Step A is repeated 5 times
And the number of repetitions of the process B is 15 times.

In this case, as schematically shown in FIG.
A barrier film 73 having the Ti thin film 57, the TiN thin film 58, and the Ti thin film 59 formed in this order was obtained. This barrier film 7
When an Al thin film was formed on the three surfaces by a two-step flow method, the Al thin film was formed on the surface of the Ti thin film 59 having good wettability. Therefore, it was possible to completely fill the bottom of the 0.5 μm contact hole 62 with the Al thin film. did it. The growth amount, step coverage, composition, and barrier properties of the barrier film 73 are the same as those of the first and second examples.
It was equivalent to 3 ', 63.

In the above embodiment, the refractory metal was Ti
Although the case where is used has been described, a gas containing W or Ta in the molecule can be used. In addition, NH ₃ gas was used as the nitrogen-containing gas, but instead of NH ₃ gas, N ₂ gas and NH ₄ gas were used.
Gas or N ₂ O gas can be used. Further, two or more kinds of NH ₃ gas, N ₂ gas, NH ₄ gas and N ₂ O gas may be used in combination.

Further, in the above embodiment, a chloride gas of a high melting point metal was used, but a fluoride gas of Ti, W or Ta,
Chloride gas, bromide gas, iodide gas, alkoxide gas, TDMAT (Ti [N (CH ₃ ) ₂ ] ₄ : tetrakisdimethylaminotitanium), TDEAT (Ti [N (C ₂
H ₅ ) ₂ ] ₄ : An organometallic compound gas such as tetrakisdiethylaminotitanium can be used. Further, even if the Ar purge step is omitted, almost the same film can be obtained.

A process using a tungsten fluoride gas will be described as a fourth example of the present invention with reference to the flowchart of FIG. First, the substrate was loaded into the process chamber 20 (Step W ₁ ), placed on a hot plate 21 whose temperature was controlled at 300 ° C., and the substrate was temperature-controlled (Step W ₂ ).

N is introduced into the process chamber 20 by the gas introduction system.
H ₃ gas was introduced and filled at a pressure of 2 × 10 ⁻¹ Torr for 2 seconds (step W ₃ ). Then, the chamber is evacuated (step W
₄ ) The pressure in the process chamber 20 was lowered to 5 × 10 ⁻³ Torr in 10 seconds. At this time, the reservoir tank 25 was not used.

From this state, WF ₆ gas is introduced into the process chamber 20 and filled at a pressure of 2 × 10 ^-1 Torr for 2 seconds.
After (Step W ₅ ), vacuum evacuation is performed in the same manner, and 5 × 10 ⁻³
The pressure was reduced to r in 10 seconds. The process from the introduction of the NH ₃ gas to the exhaust of the WF ₆ gas (steps W _{3 to} W ₆ ) was repeated 50 times without introducing the argon gas.
(Step W ₉ ).

After the substrate is unloaded (Step W ₁₀ ),
The cross section of the substrate was observed using SEM. Figure 1 shows the results.
This is schematically indicated by reference numeral 15 of 3. The formed barrier film (W
The thickness of the N thin film 83 is 200 と も に for both the substrate surface, the contact hole bottom surface, and the contact hole side surfaces (symbols a to c).
And grown conformally, with good step coverage. The composition of the obtained barrier film 83 was analyzed using an Auger electron spectrometer. The result was WN _x , x = 0.4 to 0.6.

An Al thin film was formed on the surface of the barrier film 83 by a two-step flow method in the same manner as in the first example. As in the case shown in FIG. It was filled with a low-temperature Al thin film and a second high-temperature Al thin film. Also in this case, no spike due to aluminum diffusion was observed in the silicon substrate.

This barrier film 83 was also formed while changing the substrate temperature, and the relationship with the barrier property was examined. The results are shown in the graph of FIG. The horizontal axis T is the substrate temperature, and the vertical axis F is
In the same manner as above, F = the number of contact holes with no leakage / the total number of contact holes.

From the graph of FIG.
At a temperature lower than 0 ° C. or higher than 700 ° C., the F value of the obtained barrier film 83 decreases. Therefore, in the case of the barrier film 83 made of a WN thin film, it is understood that a temperature range of 250 ° C. or more and 600 ° C. or less is suitable.

In the first to fourth examples, a step of performing a plasma treatment after the formation of the barrier film is added to reduce the specific resistance between the barrier film and the metal thin film formed on the surface thereof. You may do so.

[0073]

As described above, a barrier film having excellent step coverage and barrier properties can be obtained. A high-purity barrier film having a stoichiometric composition can be obtained.

[Brief description of the drawings]

FIG. 1 shows an example of a CVD apparatus that can be used in the present invention.

FIG. 2 is a flowchart for explaining a process of a first example of the present invention.

FIG. 3 is a flowchart for explaining a process in which the first example is modified.

FIG. 4A is a flowchart for explaining a Ti thin film forming step of a second example. FIG. 4B is a flowchart for explaining a TiN thin film forming step of a second example.

FIG. 5 is a flowchart for explaining the process of the second example of the present invention.

FIG. 6 is a flowchart for explaining a process of a third example of the present invention.

FIG. 7 is a view for explaining a cross section of the barrier film obtained in the first example.

FIG. 8 is a sectional view showing a state in which an Al thin film is formed on the surface.

FIG. 9 is a view for explaining a cross section of the barrier film obtained in the second example.

FIG. 10 is a view for explaining a cross section of the barrier film obtained in the third example.

FIG. 11 is a graph for explaining a relationship between a substrate temperature and a barrier property when a TiN thin film is formed.

FIG. 12 is a flowchart illustrating a process of a fourth example of the present invention.

FIG. 13 is a view for explaining a cross section of the barrier film obtained in the fourth example.

FIG. 14 is a graph for explaining a relationship between a substrate temperature and a barrier property when a WN thin film is formed.

FIG. 15 shows a sputtering apparatus used in a conventional barrier film forming method.

FIGS. 16A to 16C are diagrams for explaining characteristics of a conventional barrier film.

[Explanation of symbols]

5, 5 ', 15 ... substrate 20 ... vacuum chamber 53,
63, 73, 83 ... barrier films 53, 56, 58,
83 ... Nitride thin film of high melting point metal 55, 57, 59
…… High melting point metal thin film

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Kenzo Nagano 523 Yokota, Yamatake-cho, Yamatake-gun, Chiba Japan Nippon Vacuum Engineering Co., Ltd. Inside Vacuum Technology Co., Ltd.Chiba Super Materials Research Laboratory (72) Inventor Yasuhiro Takuma 523 Yamatake-cho, Yamatake-gun, Chiba Prefecture Japan Vacuum Technology Co., Ltd. 523 Japan Vacuum Technology Co., Ltd.

Claims (9)

[Claims] 1. A substrate is carried into a vacuum chamber and heated to a predetermined temperature. Then, a nitrogen-containing gas and a high-melting metal gas are introduced, and a nitride thin film of a high-melting metal is formed on the substrate. A method of forming a barrier film, wherein one of the nitrogen-containing gas and the high-melting metal gas is introduced, and one of the gases is evacuated, and then the other gas is introduced. A method of forming a barrier film, comprising repeating a step of evacuating a gas a plurality of times. 2. When forming the nitride thin film of the high melting point metal, after evacuating the other gas, introducing a purge gas before introducing the one gas, and evacuating the purge gas. The method for forming a barrier film according to claim 1, wherein: 3. The method according to claim 1, wherein the substrate is maintained at a temperature of 200 ° C. or more and 800 ° C. or less when forming the nitride thin film of the high melting point metal. Barrier film forming method. 4. The method of forming a barrier film according to claim 1, wherein the step of introducing the high-melting metal gas includes the step of forming the high-melting metal nitride thin film before forming the high-melting metal nitride thin film. A method of forming a barrier film, comprising evacuating and forming a high-melting-point metal thin film at an interface between the nitride thin film of the high-melting-point metal and a substrate. 5. After forming the high melting point metal nitride thin film, introducing a high melting point metal gas and evacuating to form a high melting point metal thin film on the surface of the high melting point metal nitride thin film. The barrier film forming method according to any one of claims 1 to 4, wherein: 6. When introducing the high-melting-point-containing metal gas,
6. The method according to claim 5, wherein the reducing gas is introduced together.
The method for forming a barrier film according to the above. 7. The gas containing a high-melting point metal selected from the group consisting of Ti, Ta, and W in a molecule thereof. 2. The method for forming a barrier film according to claim 1. 8. The method according to claim 1, wherein any one of fluoride gas, chloride gas, bromide gas, iodide gas, alkoxide gas, or organic gas, or two or more gases is used as the high-melting point metal gas. The method for forming a barrier film according to claim 7, wherein 9. The nitrogen-containing gas may be N ₂ gas, N ₂ H
₄ gas, NH ₃ gas, N or one ₂ O gas, or the barrier film forming method according to any one of claims 1 to 8, characterized by using two or more gases.