JPH11131233A - Production of titanium nitride thin coating film and cvd device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the formation of a coating film good in step coverage even to a contact hole high in an aspect ratio, at the time of producing titanium nitride thin coating film by using TDAAT and a trace amt. (10 to 100 sccm) of gas to be added, by suitably deciding the flow rates and flow velocities of various gases. SOLUTION: The flow rate of TDAAT is set to 0.004 to 0.2 g/min, the flow rate of a primary carrier gas is set to 100 to 1000 sccm, the flow rate of the gas to be added is set to 10 to 100 scc, and the flow rate of a secondary carrier gas is set to 10 to 500 sccm. A gaseous mixture (a primary gaseous mixture 10) of the TDAAT and the primary carrier gas is fed to the inside of a reaction vessel from a primary exhaust nozzle 56, and a gaseous mixture (a secondary gaseous mixture 70) of the gas to be added and the secondary carrier gas is fed to the inside of the reaction vessel from a secondary exhaust nozzle 58. The pressure in the reaction vessel is regulated to 0.1 to 10 Pa. Preferably, the flow velocity of the secondary gaseous mixture is regulated to >=0.17 m/sec, and the center distance L between the primary exhaust nozzle 56 and the secondary exhaust nozzle 58 is preferably regulated to >=1 cm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a titanium nitride thin film by a CVD method and a CVD apparatus therefor.

[0002]

2. Description of the Related Art As a method for growing a titanium nitride thin film on a substrate such as a semiconductor device, various electronic parts, and various sensors, a reactive sputtering method using a titanium metal target and nitrogen gas has been mainly used. Have been done. In recent years, with the miniaturization of silicon large-scale integrated circuits,
The design rule for DRAMs of 64 megabits or more has been reduced to about 0.35 μm or less, and the aspect ratio of contact holes of devices has been increasing. When a titanium nitride thin film is used as a barrier metal for this contact hole, if a titanium nitride thin film is formed by a conventional reactive sputtering method, there is a problem that the step coverage is not good. If the step coverage is inferior, it is expected that the electrical characteristics of the contact hole will deteriorate, which will be a serious problem in manufacturing a next-generation device. Therefore, it is expected that a conformal barrier metal is formed by using a CVD method having excellent contact hole filling characteristics and coverage characteristics.

[0003] Against such a background, a technique for producing a titanium nitride thin film by a CVD (chemical vapor deposition) method has recently attracted attention. At present, various CVD methods and source gases have been proposed for producing a titanium nitride thin film. One of them is tetrakisdialkylaminotitanium (hereinafter abbreviated as TDAAT), which is a kind of organometallic compound. There is a technology using. FIG. 8 shows the chemical structural formula of this TDAAT. In this chemical formula, R is an alkyl group.
What converted this R into an ethyl group is tetrakis diethylaminotitanium (hereinafter abbreviated as TDEAT),
What converted to a methyl group is tetrakisdimethylaminotitanium (hereinafter abbreviated as TDMAT).

[0004] These organic titanium compounds are liquids at room temperature and atmospheric pressure.
Along with a carrier gas such as H ₂ , Ar, or N ₂ , the gas is supplied into the reaction vessel through a shower head. Further, an additive gas (for example, ammonia gas) that chemically reacts with the organic titanium compound is also supplied into the reaction vessel. A substrate is provided in the reaction vessel, and the substrate is maintained at a predetermined reaction temperature.

The reaction between the organic titanium compound and the additive gas produces titanium nitride, and a titanium nitride film adheres to the substrate. It is known that the electrical characteristics and the step coverage of the attached titanium nitride depend on the flow rate of the organic titanium compound reacting in the reaction vessel with the additive gas, the substrate temperature and the reaction pressure.

For example, Raajimaker states that “Thin solid fil
ms, 247 (1994) 85 ”and references cited therein,
T is supplied to a reaction vessel together with Ar as a carrier gas, and a titanium nitride thin film is prepared using ammonia gas (NH ₃ ) as an additional gas. The flow rate of the ammonia gas is 1000 sccm or more. When the obtained titanium nitride thin film was deposited in a contact hole having a diameter of 0.8 μm and an aspect ratio of 1, the step coverage was as good as 85%. However, in a contact hole having a diameter of 0.35 μm or less as used in a 64-Mbit DRAM, it is expected that the step coverage will be less than 20%.

[0007] Jackson et al., "RL Jackson, EJ
MCineney, B.Roberts, J.Strupp, A.Velaga, S.Patel,
and L. Halliday, Proc. Advanced Metallization for U
LSIApplication, ed. By DPFavreau, Y. Shacham-Diam
ond, and Y.Horiike (Mat.Res.Soc., Pittsburgh, PA,
1994), p.20 ”, the TDEAT raw material is vaporized through a vaporizer, and this is vaporized together with nitrogen gas as a carrier gas.
It is fed into the reaction vessel through a shower head. Further, an ammonia gas (NH ₃ ) is added through a shower head in another path to produce a titanium nitride thin film. This document reports, in particular, the effect of the ratio of the TDEAT raw material and the supply amount of ammonia gas. The diameter is 0.
In a 35 μm contact hole having an aspect ratio of 3.4, the film forming temperature is 350 ° C. and the pressure is 10 to 50 Torr.
Under the condition r, the step coverage decreases from 65% to about 20% with an increase in the amount of added ammonia gas. On the other hand, when the film formation temperature was increased to 425 ° C., the step coverage was 5% in the same contact hole.
It has dropped to. When the flow rate of the ammonia gas is increased with respect to TDEAT, the step coverage of the fine contact hole becomes insufficient.

On the other hand, Intermann et al., "A. Intermann and
H.Koerner, J. Electrochem.Soc., Vol.140, No.11 (1
993) 3215 ", regarding the cause of the step coverage degradation due to the addition of ammonia gas as described above, T
It reports in detail that step coverage deteriorates due to a rapid chemical reaction between DMAT and ammonia gas.

Japanese Patent Application Laid-Open No. Hei 8-291385 describes that
A structure of a shower head for introducing a gas when a titanium nitride thin film is formed by a CVD method using TDEAT and ammonia gas is disclosed. In this shower head, the TDEAT gas and the ammonia gas pass through separate gas flow paths, so that these gases are not mixed in the shower head.

[0010]

The above-mentioned Jackson et al. And I
In the prior art of ntermann et al., it was clarified that the addition of ammonia gas to TDAAT deteriorated the step coverage of the contact hole. It has become a big problem to adopt it as mass production technology. Note that a titanium nitride thin film can be formed without adding ammonia gas, but in that case, there is a problem that carbon is included in the film.

An object of the present invention is to provide a method and an apparatus capable of improving the step coverage of contact holes and grooves when a titanium nitride thin film is formed by a CVD method using TDAAT as a raw material. Another object of the present invention is to provide a method and apparatus for suppressing a titanium nitride generation reaction in a space between a shower head for gas supply and a substrate and promoting a titanium nitride generation reaction on a substrate surface. is there.

[0012]

According to the present invention, there is provided a method for producing a titanium nitride thin film using a tetrakisdialkylaminotitanium (TDAAT) and an additive gas reacting therewith.
A titanium nitride thin film is deposited on a substrate by a VD method, and a flow rate range of TDAAT, a first carrier gas therefor, an additive gas, and a second carrier gas therefor is appropriately determined. Has the main features. That is, the flow rate of TDAAT is 0.004 to 0.2 g / mi.
n, and the flow rate of the first carrier gas is 100 to 1000 s
ccm, the flow rate of the additional gas is 10 to 100 sccm, and the flow rate of the second carrier gas is 10 to 500 sccm. A mixed gas of TDAAT and the first carrier gas (first mixed gas) is supplied into the reaction vessel from the first ejection hole, and a mixed gas of the additional gas and the second carrier gas (second mixed gas) is supplied from the second ejection hole. Supply into the reaction vessel. Thus, the first
Since the mixed gas and the second mixed gas are supplied into the reaction vessel through supply paths of different systems, the two types of mixed gas do not come into contact with each other before entering the reaction vessel. The pressure inside the reaction vessel is set to 0.1 Pa to 15 Pa.

The flow rates of TDAAT and additive gas can be adjusted by respective flow controllers. Also, the flow rate of the second carrier gas for the additive gas can be adjusted by a dedicated flow controller.
Thereby, the additive gas is supplied at a very small flow rate (10 to 100 sccm).
It became possible to supply by. That is, even if the additive gas is set to such a small flow rate, the flow rate of the additive gas can be maintained at a desired value by adjusting the flow rate of the second carrier gas. This allows the additive gas to be transported to the surface of the substrate without lowering the pressure of the additive gas introduction system. Therefore, a rapid chemical reaction in the space between TDAAT and the added ammonia gas can be suppressed, the surface reaction on the substrate can be increased, and the step coverage of the titanium nitride thin film can be improved.

TDAAT includes TDEAT and TDM
AT can be used. The additive gas that reacts with TDAAT is typically ammonia gas, and other than that, methylhydrazine can also be used. It is optimal to use nitrogen gas for both the first carrier gas and the second carrier gas. The carrier gas does not contribute to the chemical reaction of TDAAT. By adjusting the flow rate of the carrier gas, the flow rates of the TDAAT and the additive gas can be adjusted.

In the present invention, the flow rate of the additive gas (typically, ammonia gas) is set to 10 to 100 sccm, and the step coverage is improved by making the flow rate considerably smaller than that of the conventional technique. The flow rate conditions of other gases when such a small amount of additive gas is used are determined.

The flow rate of TDAAT is 0.004 to 0.2
g / min. Set the flow rate of TDAAT to 0.
If it is less than 004 g / min, the deposition rate of the titanium nitride thin film becomes very low, about 1 nm / min or less, which is not practical. The upper limit of the flow rate of TDAAT is the maximum value of the flow rate that can be vaporized, which is about 0.2 g / min.

The flow rate of the first carrier gas is 100 to 100
It is within the range of 0 sccm. In order to vaporize TDAAT, a flow rate of at least about 100 sccm is required. On the other hand, increasing the flow rate of the first carrier gas is not preferable because the pressure in the reaction vessel increases. From such a viewpoint, the flow rate of the first carrier gas is preferably set to 1000 sccm or less.

The flow rate of the additive gas is in the range of 10 to 100 sccm, which is considerably smaller than in the prior art. TDA
Since the reaction between the AT and the additional gas is used, the flow rate of the additional gas needs to be at least about 10 sccm. on the other hand,
As the flow rate of the additive gas is increased, the step coverage tends to decrease, but up to about 100 sccm is a practical limit for maintaining good step coverage.

The flow rate of the second carrier gas is 10 to 500 sc
cm. The flow rate of the second carrier gas is set to 10
If the thickness is less than sccm, the step coverage of the titanium nitride thin film is undesirably reduced. When the flow rate of the second carrier gas is set to 10 sccm or more, the step coverage is improved. Even if the flow rate of the second carrier gas is further increased, the step coverage hardly changes. On the other hand, increasing the flow rate of the second carrier gas is not preferable because the pressure in the reaction vessel increases. From such a viewpoint, the flow rate of the second carrier gas is preferably set to 500 sccm or less.

In the present invention, the flow rate of the second mixed gas is preferably set to 0.17 m / sec or more. When the flow rate of the second mixed gas is 0.17 m / sec or more, the step coverage of the titanium nitride thin film is improved. Since the second mixed gas contains an additional gas, setting the flow rate of the second mixed gas to 0.17 m / sec or more is the same as setting the flow rate of the additional gas to 0.17 m / sec or more. is there.

The first mixed gas and the second mixed gas are supplied into the reaction vessel from the first ejection port and the second ejection port provided in the shower head. These ejection holes have a relatively small diameter, and by dispersing and providing a large number of such ejection holes, the film thickness distribution of the titanium nitride thin film is improved. When the diameter of each of the first ejection hole and the second ejection hole is 4 mm or less, and the distance L between the centers of the first ejection hole and the second ejection hole (hereinafter, referred to as the hole interval) is 1 cm or more, titanium nitride is used. Better step coverage of the thin film.

Here, the role played by the hole interval L will be considered. Assuming that the pressure inside the reaction vessel is 50 mTorr (= 6.7 Pa), the mean free path of gas molecules is about 1 mm. Under this pressure condition, the gas molecules collide with other gas molecules about 10 times on average while traveling 1 cm. Therefore, if the hole interval L is set to 1 cm, T
DAAT collides with other gas molecules about 5 times, resulting in about 5
mm, on the other hand, when the additive gas emitted from the second ejection hole collides with other gas molecules about five times and advances about 5 mm, the two meet each other. That is, it does not occur that the TDAAT and the additive gas meet immediately, and the two react rapidly. By setting the hole interval to be equal to or larger than the predetermined value, a spatial reaction between the additive gas and TDAAT can be suppressed.

When TDAAT and an additive gas undergo a chemical reaction to form a titanium nitride thin film, two places where the chemical reaction occurs are considered: a space in a reaction vessel and a substrate surface. The reaction that occurs in the reaction vessel is called a space reaction, and the reaction that occurs on the substrate surface is called a surface reaction. In order to improve the step coverage of the titanium nitride thin film, it is important to suppress the spatial reaction as much as possible and to mainly perform the surface reaction. The flow rate of the second mixed gas is set to 0.17 m / sec or more, and the hole interval L is set to 1 cm.
Any of the above is effective in suppressing the spatial reaction.

[0024]

FIG. 1 is a structural view of an example of a CVD apparatus for carrying out a method for producing a titanium nitride thin film according to the present invention. A substrate holder 18 is provided inside the reaction vessel 10, and a substrate 20 is attached to the substrate holder 18. A titanium nitride thin film is formed on the surface of the base 20. A shower head 54 for gas introduction is provided so as to face the base holder 18, and through this shower head 54, a source gas can be introduced from the source gas introduction system 22 and an additive gas can be introduced from the additive gas introduction system 24. .

The reaction vessel 10 is made of stainless steel, and can be evacuated by the exhaust system 12 to keep the inside airtight. The exhaust system 12 includes a turbo molecular pump 26 and a dry pump 28. The exhaust system 12 can evacuate the inside of the reaction vessel 10 to a pressure of 10 -4 Pa, and can maintain a desired pressure. The dry pump 28 is V06 manufactured by Anelva.
It is a 0F dry pump, and the pumping speed is 1000 liter / min.

As vacuum gauges for measuring the pressure in the reaction vessel 10, there are a first vacuum gauge 14 for low vacuum and a second vacuum gauge 16 for high vacuum. The first vacuum gauge 14 is a high-precision diaphragm vacuum gauge having a pressure measurement range of 0.1 Pa to 133 Pa. In this embodiment, a Baratron TYP manufactured by MKS is used.
E128A is used. The second vacuum gauge 16 is an ionization vacuum gauge having a pressure measurement range of 10 ⁻² Pa to 10 ⁻⁶ Pa,
In this embodiment, a BA gauge UGD-1 manufactured by Anelva is used.
S is used.

The substrate holder 18 has a substrate heating device 30 for heating the substrate 20. The substrate heating device 30 includes a thermocouple 32 for measuring the temperature of the substrate 20, a heater 34, and a heating power supply 35. The heating power supply 35 performs PID control of the substrate temperature (or other control methods such as PI control, ON-OFF control, and fuzzy control) based on the measured temperature value.

The raw material gas introducing system 22 is a liquid raw material T
Raw material container 36 containing DAAT and liquid TDAAT
, A first flow controller 40 for controlling the flow rate of the vaporized TDAAT gas, and a TDAAT
It comprises a gas cylinder 42 containing a carrier gas (first carrier gas) for gas, and a second flow controller 44 for controlling the flow rate of the first carrier gas. The vaporizer 38 is a VU-104 manufactured by Lintec Corporation and does not perform bubbling. The vaporized TDAAT is mixed with the first carrier gas and supplied to the shower head 54 via the first supply path 76.

The additive gas introduction system 24 includes an additive gas cylinder 46 containing an additive gas (a typical example is ammonia gas),
A third flow controller 48 for controlling the flow rate of the additional gas, a gas cylinder 50 containing a carrier gas (second carrier gas) for the additional gas, and a fourth flow control for controlling the flow rate of the second carrier gas And a container 52. The additive gas is mixed with the second carrier gas and supplied to the shower head 54 via the second supply path 78.

To describe typical examples of various gases, the source gas is TDEAT, the additive gas is ammonia gas, and the first carrier gas and the second carrier gas are nitrogen gas. In the following description, the gas of this representative example is used unless otherwise specified.

FIG. 2 shows a shower head 5 for introducing gas.
4 is a plan view, and FIG. 3 is a sectional view taken along line AA of FIG. In FIG. 2, on the upper surface of the shower head 54, there are a large number of first ejection holes 56 for ejecting a source gas (TDAAT), and around the first ejection holes 56, an additive gas (ammonia gas) is ejected. 8 second for
There is a spout 58. This drawing is a schematic drawing, and in the actual shower head 54, about 30 to 40 first ejection holes 56 are formed on the upper surface having a diameter of about 250 mm. Are formed with eight second ejection holes 58. These eight second ejection holes 58
Are arranged at equal intervals on the same circumference around the first ejection hole 56. In this embodiment, the diameter of the first ejection hole 56 is 3 mm, and the diameter of the second ejection hole 58 is 1.5 mm. The first ejection hole 56 and the second ejection hole 58
Has an important meaning as described later. Hereinafter, this center-to-center distance L is referred to as a hole interval.

In FIG. 3, a mixed gas (first mixed gas) 60 of a source gas and a carrier gas passes through a first supply path 76 and first enters a first diffusion chamber 62 of the shower head 54. Next, through a dispersion hole 66 formed in the dispersion plate 64,
It enters the second diffusion chamber 68. And these diffusion chambers 64,
After being uniformly mixed at 68, the mixture exits the reaction vessel through the first ejection holes 56. On the other hand, a mixed gas (second mixed gas) 70 of the additive gas and the carrier gas is supplied to the second supply path 7.
8, enters the third diffusion chamber 72 of the shower head 54, passes through the second ejection hole 58, and exits inside the reaction vessel.

FIG. 4 is a graph showing the relationship between the step coverage of the titanium nitride thin film produced by using the CVD apparatus of FIG. 1 and the hole interval L of the shower head. The horizontal axis indicates the hole interval L on the upper surface of the shower head, and the vertical axis indicates the step coverage of the titanium nitride thin film in the contact hole having a hole diameter of 0.5 μm and an aspect ratio of 4. The conditions for producing the titanium nitride thin film are as follows.
TDEAT is used as raw material, and its flow rate is 0.004 ~
0.2 g / min. Nitrogen gas was used as the first carrier gas, and the flow rate was 350 sccm. Ammonia gas was used as an additive gas, and the flow rate was 10 sccm.
Nitrogen gas is used as the second carrier gas, and its flow rate is 1
00 sccm. The film forming temperature is 573 K, and the pressure in the reaction vessel is 6.7 Pa.

As can be seen from FIG. 4, the step coverage increases as the hole interval L of the shower head increases. When the hole interval L is 1 cm or more, the step coverage is maintained at 20% or more. On the other hand, when the hole interval L is less than 1 cm, the step coverage decreases, and when the hole interval is 0.5 cm, the step coverage decreases to about several percent. This tendency was the same when TDMAT was used as a raw material.

The distance between the first ejection holes 56 affects the film thickness distribution. If the space between the first ejection holes 56 is too large, the uniformity of the film thickness distribution is reduced. Considering the uniformity of the film thickness distribution, the hole interval between the first ejection holes 56 is preferably set to 5 cm or less. Considering that the second ejection holes 58 are arranged around the first ejection holes 56 as shown in FIG. 2, the hole interval L between the first ejection holes 56 and the second ejection holes 58 around the first ejection holes 56 is at most a maximum. , Which is one half of the hole interval between the first ejection holes 56. Therefore, the first ejection holes 56
When the distance between the holes is set to 5 cm, the distance L between the first ejection holes 56 and the second ejection holes 58 is 2.5 cm at the maximum.
Therefore, considering the film thickness distribution, the hole interval L is 1-2.
It is appropriate to set within the range of 5 cm.

FIG. 5 is a sectional view showing a state where a titanium nitride thin film is formed in a contact hole. Contact hole 80
Is defined as “depth H” ÷ “hole diameter D”. The step coverage in the contact hole 80 is defined as the ratio of the deposition thickness b at the bottom of the contact hole to the deposition thickness a of the titanium nitride thin film 74 other than in the contact hole. That is, step coverage (%) = (b / a) × 100. Step coverage was measured by SEM observation.

FIG. 6 is a graph showing the relationship between the step coverage of the titanium nitride thin film and the flow rate of the additional gas (ammonia gas) (flow rate near the second ejection hole). The horizontal axis is the flow rate of the ammonia gas (this is equal to the flow rate of the second mixed gas), and the vertical axis is the step coverage of the titanium nitride thin film in the above-described contact hole. The conditions for producing the titanium nitride thin film are as follows. Hole spacing L is 25m
m. TDEAT was used as a raw material, and the flow rate was 0.004 to 0.2 g / min. Nitrogen gas was used as the first carrier gas, and the flow rate was 350 sccm.
Ammonia gas was used as the additive gas, and its flow rate was 10
It varied between ２０20 sccm. Nitrogen gas was used as the second carrier gas, and the flow rate was changed so that the flow rate of the second mixed gas became a desired value. The deposition temperature is 573K,
The pressure inside the reaction vessel is 6.7 Pa.

As can be seen from FIG. 6, the step coverage sharply increases by increasing the flow rate of the ammonia gas. When the flow velocity is about 0.17 m / sec or more, the step coverage becomes good, and a good step coverage of 70% or more is obtained regardless of the flow rate of the ammonia gas at 10, 15, or 20 sccm. When the flow rate of the ammonia gas is increased from 10 sccm to 20 sccm, the step coverage tends to decrease. However, even when the flow rate of the ammonia gas is 20 sccm, the flow rate is 0.17 m.
/ Sec or more, 70% of step coverage can be secured.

In order to set the "flow rate" of the ammonia gas to a predetermined value and to change the "flow rate" of the ammonia gas, the flow rate of the second carrier gas may be changed. The flow rate of the ammonia gas (equal to the flow rate of the second mixed gas) can be determined from the flow rate of the second mixed gas, the diameter of the second ejection hole, and the pressure in the reaction vessel.

FIG. 7 is a graph showing the relationship between the step coverage of the titanium nitride thin film and the flow rate of the second carrier gas. The horizontal axis indicates the flow rate of the second carrier gas, and the vertical axis indicates the step coverage of the titanium nitride thin film in the above-described contact hole. The conditions for producing the titanium nitride thin film are as follows. The hole interval L was 25 mm. T as raw material
Using DEAT, the flow rate is 0.004-0.2 g / mi
n. Nitrogen gas was used as the first carrier gas, and the flow rate was 350 sccm. Ammonia gas was used as an additive gas, and the flow rate was 10 sccm. The deposition temperature is 5
73K, the pressure of the reaction vessel is 6.7 Pa. And
A titanium nitride thin film was prepared by changing the flow rate of the second carrier gas in the range of 0 to 100 sccm.

As can be seen from FIG. 7, when the second carrier gas is not supplied, the step coverage is about 20%. It can be seen that the step coverage sharply increases as the flow rate of the second carrier gas is increased from zero.
Increasing the flow rate of the second carrier gas to 10 sccm increases the step coverage to about 85%. If the flow rate of the second carrier gas is further increased to 20 sccm, the step coverage becomes about 90%. However, even if the flow rate of the second carrier gas is further increased, the step coverage does not increase any more. Rather, increasing the flow rate of the second carrier gas to 100 sccm tends to slightly reduce step coverage. Similar results were obtained when the source gas was TDMAT.

The reason why the step coverage is improved by flowing the second carrier gas at a predetermined flow rate or more can be explained by the following mechanism. If the additional gas is supplied at a small flow rate of about 10 to 20 sccm without using the second carrier gas, the following phenomenon is considered to occur. In FIG. 3, since the flow rate of the additive gas at the minute flow rate is not so large, after the gas flows out of the second ejection hole 58,
A part thereof diffuses through the first ejection holes 56 to the second diffusion chamber 68 of the shower head. The reason is that the partial pressure of the added gas is lower in the second diffusion chamber 68 than in the reaction vessel. As a result, the second diffusion chamber 6 is removed from the inside of the reaction vessel.
8, the reverse diffusion of the additive gas occurs spontaneously. As a result, a chemical reaction occurs between the source gas and the additive gas inside the second diffusion chamber 68, and the spatial reaction increases. Therefore, the surface reaction on the substrate is less likely to occur, and the step coverage is reduced. Further, a titanium nitride thin film is easily deposited on the shower head, and there is a problem that particles are generated due to the deposition. For the reasons described above, improvement of the step coverage cannot be expected only by supplying the additive gas at a very small flow rate. On the other hand, when the second carrier gas is mixed with the additional gas to secure a certain flow rate, the additional gas hardly diffuses to the second diffusion chamber 68.

In the experiments in which the graphs of FIGS. 4, 6 and 7 were obtained, the flow rate of TDEAT was set to 0.004 to 0.2 g / mi.
Although the flow rate of the TDEAT is negligible when the flow rate is within this range, the experimental conditions are such that such a numerical range is designated. The flow rate of TDEAT affects the deposition rate.

From the results of several experiments described above, it can be seen that the following conditions are desirable in order to obtain good step coverage in producing a titanium nitride thin film. First, as can be seen from the graph of FIG. 4, it is desirable that the hole interval L of the shower head be 1 cm or more. Next, as can be seen from the graph of FIG. 6, it is desirable that the flow rate of the additional gas be 0.17 m / sec or more. Further, as can be seen from the graph of FIG. 7, the flow rate of the second carrier gas is desirably set to 10 sccm or more.

[0045]

According to the present invention, the flow rate range of TDAAT, the first carrier gas, and the second carrier gas when a titanium nitride thin film is prepared using TDAAT and an additive gas having a very small flow rate (10 to 100 sccm). By appropriately determining the thickness, it is possible to form a film with good step coverage even for a contact hole having a large aspect ratio. The flow rate of the second mixed gas comprising the additive gas and the second carrier gas is set to 0.17 m / sec or more, and the hole interval between the first ejection hole and the second ejection hole of the shower head is set to 1c.
By setting m or more, the spatial reaction between TDAAT and the additional gas could be suppressed, and the surface reaction on the substrate was increased, thereby improving the step coverage even for a contact hole having a large aspect ratio.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an example of a CVD apparatus for performing a titanium nitride thin film manufacturing method of the present invention.

FIG. 2 is a plan view of a shower head.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a graph showing a relationship between step coverage of a titanium nitride thin film and a hole interval L of a shower head.

FIG. 5 is a sectional view showing a state where a titanium nitride thin film is formed in a contact hole.

FIG. 6 is a graph showing the relationship between the step coverage of a titanium nitride thin film and the flow rate of ammonia gas.

FIG. 7 is a graph showing the relationship between the step coverage of a titanium nitride thin film and the flow rate of a second carrier gas.

FIG. 8 is a diagram showing a chemical structural formula of TDAAT.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Reaction container 12 Exhaust system 18 Substrate holder 20 Substrate 22 Source gas introduction system 24 Additive gas introduction system 26 Turbo molecular pump 28 Dry pump 30 Substrate heating device 36 Source container 38 Vaporizer 40 First flow controller 42 First carrier gas Gas cylinder 44 second flow controller 46 gas cylinder for additional gas 48 third flow controller 50 gas cylinder for second carrier gas 52 fourth flow controller 54 showerhead 56 first ejection hole 58 second ejection hole 60 1 mixed gas 62 first diffusion chamber 64 dispersion plate 66 dispersion hole 68 second diffusion chamber 70 second mixed gas 72 third diffusion chamber 74 titanium nitride thin film 76 first supply path 78 second supply path 80 contact hole

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Romi Tobe 5-7-1 Yotsuya, Fuchu-shi, Tokyo Inside Anelva Co., Ltd.

Claims (9)

[Claims] 1. A method for producing a titanium nitride thin film, comprising supplying a tetrakisdialkylaminotitanium and an additive gas reacting with the tetrakisdialkylaminotitanium into a reaction vessel and depositing the titanium nitride thin film on a surface of a substrate heated to a predetermined temperature. Next (A) ~
A method having the characteristic of (g). (A) The flow rate of the tetrakisdialkylaminotitanium is set to 0.
Set within the range of 004 to 0.2 g / min. (A) The flow rate of the first carrier gas mixed with the tetrakisdialkylaminotitanium is set in the range of 100 to 1000 sccm. (C) The flow rate of the additive gas that reacts with the tetrakisdialkylaminotitanium is set within the range of 10 to 100 sccm. (D) The flow rate of the second carrier gas mixed with the additive gas is set to 1
Set within the range of 0 to 500 sccm. (E) A tetrakisdialkylaminotitanium is mixed with a first carrier gas, and the first mixed gas is supplied into the reaction vessel from the first ejection hole. (F) The additive gas and the second carrier gas are mixed, and the second mixed gas is supplied into the reaction vessel from the second ejection hole. (G) The pressure in the reaction vessel is set to 0.1 Pa to 15 Pa. 2. The method according to claim 1, wherein the flow rate of the second mixed gas in the second ejection hole is 0.17 m / sec or more. 3. The method according to claim 1, wherein the diameter of each of the first and second ejection holes is 4 mm or less, and the distance between the centers of any of the first ejection holes and any of the second ejection holes is reduced. A method characterized in that the length is 1 cm or more. 4. The method according to claim 3, wherein a center-to-center distance between an arbitrary first ejection hole and a second ejection hole closest to the first ejection hole is within a range of 1 to 2.5 cm. A method comprising: 5. The method according to claim 1, wherein said tetrakisdialkylaminotitanium is tetrakisdiethylaminotitanium and said additive gas is ammonia gas. 6. A reaction container capable of vacuum evacuation, an exhaust device capable of exhausting the inside of the reaction container and maintaining the inside of the reaction container at a predetermined pressure, and a gas supply device for introducing a raw material gas into the reaction container. A substrate holder for holding a substrate on which a titanium nitride thin film is deposited, and a heating apparatus for heating the substrate, a CVD apparatus for producing a titanium nitride thin film,
The said gas supply apparatus is provided with the following (A)-(C), The CVD apparatus characterized by the above-mentioned. (A) A vaporizer for vaporizing tetrakisdialkylaminotitanium as a liquid raw material. (A) A first flow controller capable of setting the flow rate of vaporized tetrakisdialkylaminotitanium to at least one of the values in the range of 0.004 to 0.2 g / min. (C) A second flow controller capable of setting the flow rate of the first carrier gas mixed with the tetrakisdialkylaminotitanium to at least any value within a range of 100 to 1000 sccm. (D) A third flow controller capable of setting the flow rate of the additive gas reacting with the tetrakisdialkylaminotitanium to at least any value within the range of 10 to 100 sccm. (E) The flow rate of the second carrier gas mixed with the additive gas is set to 1
A fourth flow controller that can be set to at least any value within a range of 0 to 500 sccm. (F) a first supply path for mixing the tetrakisdialkylaminotitanium with the first carrier gas and introducing the first mixed gas into the reaction vessel; (G) a second supply path that mixes the additive gas and the second carrier gas and guides the second mixed gas into the reaction vessel. (H) A plurality of first ejection holes leading to the first supply passage and a large number of second ejection holes leading to the second supply passage are provided, and the first mixed gas and the second mixed gas are supplied from these ejection holes to the reaction vessel. Shower head to be supplied inside. 7. The CVD apparatus according to claim 6, wherein
The diameter of the first and second ejection holes is set to 4 mm or less, and the center distance between any of the first ejection holes and any of the second ejection holes is set to 1
cm or more. 8. The CVD apparatus according to claim 7, wherein
A CVD apparatus characterized in that a center-to-center distance between an arbitrary first ejection hole and a second ejection hole closest to the first ejection hole is within a range of 1 to 2.5 cm. 9. C according to any one of claims 6 to 8,
In a VD apparatus, a plurality of second ejection holes are arranged at equal intervals on the same circumference centered on an arbitrary first ejection hole.