JP3342729B2 - Method and apparatus for forming aluminum alloy wiring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for forming aluminum alloy wiring by vaporizing an aluminum compound raw material and forming aluminum alloy wiring by chemical vapor deposition.

[0002]

2. Description of the Related Art Along with miniaturization of LSIs, an alloy thin film such as an Al-Cu alloy used for wiring of an integrated circuit device is formed by a chemical vapor deposition (CVD) method.
(Japanese Patent Laid-Open No. Hei 2-
170419).

FIG. 3 shows an example of an apparatus used in this method. In one container 50, for example, DMAH (dimethyl aluminum hydride) 51 is sealed as a raw material of an aluminum compound, and in the other container 60, as a copper compound raw material, for example, CpCuTEP (= Cu (C _{5
H 5) · P (C 2} H 5) 3) 61 is sealed, respectively bubbled by a suitable carrier gas, as it is mixed material gases and the carrier generated from the container, the reaction vessel 10 Had supplied.

[0004]

When such a method is adopted, the vapor pressure of CpCuTEP in the container is about 1 mTorr at room temperature, and DMAH is 1.7 Ton at room temperature.
rr, and the vapor pressures of both are greatly different. Therefore, when adjusting the supply amount of these raw material gases, if the heating temperature of the oil bath heating each container is changed, the response is poor due to heat transfer delay, and the supply amount is adjusted optimally. It was difficult to do. Thus, when the supply control of the aluminum source gas and the copper source gas is difficult,
When the partial pressure ratio of each source gas in the reaction vessel is not constant and the alloy thin film is deposited, the film composition differs depending on the location. When the composition of the alloy thin film is non-uniform, for example, the electromigration resistance of a portion having a small particle size or a portion having a low Cu concentration is reduced, and deterioration proceeds from this portion.

On the other hand, DMAH has a viscosity of about 4000 cP
(Centipoise), as described above, the vapor pressure is as low as about 1.7 Torr at room temperature, and at a high temperature, the raw material itself is decomposed in the container, so that the vapor pressure cannot be secured. Since such a raw material has a high viscosity or a low vapor pressure, a sufficient supply amount cannot be secured by the bubbling method shown in FIG. In particular, in the case of a high-viscosity liquid, the carrier gas sucked into the container is confined in the liquid, but it is necessary to take enough time for the bubbles to develop sufficiently for the bubbles to be broken and the carrier gas to be released. Yes, stable bubbling cannot be performed.
For this reason, there is a drawback that the supply amount varies greatly with time.

Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to sufficiently supply each source gas into a reaction vessel when forming an aluminum alloy wiring by chemical vapor deposition. Another object of the present invention is to provide a method and an apparatus for forming an aluminum alloy wiring, which enhance the controllability of the supply amount.

[0007]

SUMMARY OF THE INVENTION Accordingly, a method of forming an aluminum alloy wiring according to the present invention is to supply a carrier gas to an aluminum compound raw material sealed in a first housing to generate an aluminum raw material gas and to form a second housing. Carrier gas is supplied to the copper compound raw material sealed in the body to generate copper raw material gas, and aluminum raw material gas and copper raw material gas generated in each container are supplied together with the carrier gas into the reaction vessel, and the chemical vapor deposition is performed. In the method for forming an aluminum alloy wiring by forming an aluminum alloy wiring, the first container or the second container is formed under the condition that the pressure in each container is set higher than the pressure in the reaction vessel and lower than the atmospheric pressure . Income
Measure the pressure in one of the containers and determine the pressure in one container.
Change the pressure in the other container following the fluctuation of force
It is characterized by the following.

[0008]

An apparatus for forming an aluminum alloy wiring according to the present invention comprises a first container enclosing an aluminum compound raw material, a second container enclosing a copper compound raw material, and each of the first and second containers. A raw material gas is introduced together with a carrier gas, and a reaction vessel for forming an aluminum alloy wiring by chemical vapor deposition is provided in a raw material gas supply line between the reaction vessel and each container in the apparatus for forming an aluminum alloy wiring. Pressure adjusting means for adjusting the flow rate of the source gas flowing through the source gas supply line to adjust the pressure in each container, pressure detecting means for detecting the pressure of each container, and detection signals from each pressure detecting means. Control means for performing drive control of each corresponding pressure adjusting means, and one of the first container or the second container.
The pressure in the other container changes following the pressure change in the other container.
Main control means for controlling each of the control means so that
It is characterized by having .

[0010]

[0011]

Before describing the operation of the present invention, the vaporization rate when a carrier gas is supplied into the container will be described.

The volume newly generated by the carrier gas per unit time (1 minute in this case) is ΔV (cc / mi).
n), the vaporization efficiency is η (0 <η ≦ 1), the vapor pressure of the raw material (T
orr) is P _vap , and the vaporization rate Q _v (mol / m)
in) can be expressed as follows: Q _v = η · P _vap · ／ V / (R / T) (1) Here, R is a gas constant (cc · To)
rr / mol · K) and T is the temperature (K). That is, assuming that the supply speed of the carrier gas is F (SCCM) and the vaporization pressure (in the case of the container, the internal pressure) is P, ΔV = 760 F · T / 273P (2) Therefore, the supply rate Q (mol / mi) of the vaporized raw material
n) can be represented by the following equation. _{Q = η · (P vap /} P) · (F / V M) ... (3) where V _M is the molar volume (cc). From equation (3),
It can be seen that reducing the pressure P in the container is effective for increasing the raw material supply rate. Therefore, in order to increase the supply amount, it is understood that at least the pressure of the vaporizing atmosphere needs to be lower than the atmospheric pressure. It is also understood that maintaining P constant is essential for keeping Q constant.

Further, when the pressure in the container is reduced, the sucked gas tends to form bubbles against the viscosity of the raw material, and the bubbling is stabilized even with a high-viscosity liquid of 1000 cP or more.

However, from the viewpoint of the stability of the vaporized atmosphere, the effect of only reducing the pressure of the vaporized atmosphere is not sufficient.
When the internal pressure of the container suddenly changes due to a change in the form of the vaporized substance (for a liquid, collapse of bubbles, abnormal bumping or viscosity, etc. over time), a change in the pressure of the reaction vessel to which the container is connected is caused. . Conversely, when the internal pressure of the reaction vessel changes for some reason, the vaporization pressure fluctuates. Therefore, setting the pressure of the container higher than the pressure of the reaction vessel has an effect of securing a margin for the fluctuation. The above is the action of the requirement that the pressure of the reaction vessel be lower than the pressure of the container and the pressure of the vaporized atmosphere be kept lower than the atmospheric pressure.

Further, by changing the pressure of the other container following the pressure of the one container, even if the pressure of one container temporarily fluctuates greatly, the other is adjusted in accordance with this fluctuation. The pressure of the container is adjusted, and the ratio of the supply amounts of the two source gases is always kept constant.

In the apparatus for forming an aluminum alloy wiring, a means for separating the pressure between the reaction vessel and each container is inevitably required, and usually a pressure adjusting means such as a pressure adjusting valve is used. The pressure in each container can be adjusted by this pressure adjusting means. The pressure of the vaporized atmosphere in each container is detected by the pressure detecting means, and the control means drives and controls the pressure adjusting means, so that the pressure of the vaporized atmosphere is automatically kept constant.

Further, when a main control means for controlling each control means is provided, it is possible to change the pressure of the other container following the pressure of one container.
The feed rate of the source gas is always kept constant.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus for forming an aluminum alloy thin film according to this embodiment will be described below with reference to the accompanying drawings.

FIG. 1 shows the entire configuration of a forming apparatus used in this embodiment. This forming apparatus includes a reaction vessel 11 for forming an alloy thin film by chemical vapor deposition at the center, and a source gas supply line for supplying each source gas to the reaction vessel 11 on both sides thereof, one system each. Each line has a container 6 for generating a source gas.
a and 6b.

A substrate 13 held by a substrate holder 16 is disposed in the reaction vessel 11, and a nozzle 12 is provided facing the substrate 13. Source gases and the like described later are supplied through the nozzle. Further, a heater 17 is provided in the substrate holder 16 and generates heat by applying an AC voltage to heat the substrate 13 to a predetermined temperature.

In addition, each source gas supply line is supplied with a suitable carrier gas such as hydrogen or helium gas from carrier gas cylinders 1a and 1b, respectively, and the carrier gas is supplied to flow controllers (mass flow controllers) 2, 3,
Through the stop valves 4 and 5, the container 6
Enter a, 6b. The containers 6a and 6b are accommodated in oil baths 8a and 8b whose temperature is controlled, and the raw materials 7a and 7b are sealed therein.
The raw material gas and the carrier gas generated by bubbling pass through a pressure gauge and a pressure controller 9 and a pressure control valve 10,
It is supplied into the reaction vessel 11. Note that reference numbers 14a,
Reference numeral 14b is a control device for adjusting the flow rate of the supplied source gas. When supplying raw materials using this device,
Each container 6a,
The pressure in 6b is controlled to be constant below atmospheric pressure.
The pressure in the reaction container 11 is controlled by the container 6a,
The pressure is maintained lower than the pressure in 6b.

When the pressure is actually controlled, the carrier gas may be controlled not only in the containers 6a and 6b but also between the flow controllers 2 and 3 and the pressure control valve 10. The temperatures of the oil baths 8a and 8b are determined in consideration of the thermal stability and vapor pressure of the raw material. For example, when DMAH (dimethyl aluminum hydride) is used as the aluminum compound raw material, the bubbling pressure is 760 to 20.
The range of Torr and the bubbling temperature are desirably about 20 to 100 ° C., and CpCuTEP is used as a copper compound raw material.
If _{(= C 5 H 5 CuP (} C 2 H 5) 3) , the bubbling pressure in the range of 20～760Torr, bubbling temperature is desirably about 20 to 150 ° C..

<Example 1> An Al-Cu alloy thin film was formed by using the apparatus configured as described above. Raw material 7
a is DMAH as an aluminum compound raw material, and CpCu as a copper compound raw material as a raw material 7b.
TEP was used. Hydrogen gas was used as a carrier gas, and each flow rate was adjusted to 100 sccm by flow controllers 2 and 3.
Controlled and shed. The pressure in the container 7a was controlled to be constant at 500 Torr by the pressure controller 9 and the pressure control valve 10, and the oil bath temperature was kept at 50 ° C. The DMAH flow rate at this time was 1.7 sccm. on the other hand,
The pressure in the container 7b was controlled to be constant at 170 Torr by the pressure controller 9 and the pressure control valve 10, and the oil bath temperature was maintained at 100 ° C. Also, all the piping
It was heated to 120 ° C. by a heater not shown.

As a film forming condition, the pressure in the reaction vessel 11 is 2
Torr, the temperature of the substrate 13 was 250 ° C. As a result of forming a film under such conditions, a film having good uniformity was formed.
Further, as shown in FIG. 2, the variation in film thickness for each run could be suppressed to less than 5%.

<Embodiment 2> In addition to the apparatus shown in FIG. 1, a main controller 20 for controlling the respective controllers 14a and 14b is further provided so as to follow the pressure fluctuation in the container 6a in which DMAH is sealed. Then, the pressure in the container 6b was adjusted. The conditions such as the raw material, the carrier gas, its flow rate, the oil bath temperature, and the film forming conditions were the same as in Example 1. As a result of forming a film under such conditions, it was confirmed that the film thickness variation was further suppressed as compared with Example 1.

COMPARATIVE EXAMPLE 1 Using the apparatus shown in FIG. 1, various pressures in the container were set to 760 Torr (atmospheric pressure), and A
An l-Cu alloy thin film was formed. Raw materials, carrier gas, its flow rate, oil bath temperature, etc.
Same as Example 1. As a result of forming a film under such conditions, a mottled film having poor uniformity was formed.

Comparative Example 2 Using the apparatus shown in FIG. 1, the control device was removed and the opening of the pressure control valve was manually adjusted. The conditions such as the raw material, the carrier gas, the flow rate thereof, the oil bath temperature and the film forming conditions were the same as those in Example 1, and 40 runs of the Al—Cu alloy were formed. FIG. 2 shows the change in film thickness in this case. A variation of up to 15% was confirmed in the Auger depth profile.

Such fluctuations mainly include fluctuations in the pressure in the reaction vessel and fluctuations in the internal pressure of the container caused by changes in the viscosity and amount of the raw material, and thus the DMAH flow rate fluctuates. Therefore, DMAH and CpCuTEP in the reaction vessel are changed. It is considered that the partial pressure ratio is not constant.

In each of the above embodiments, an example is shown in which the source gases are mixed on the supply line and supplied into the reaction vessel. However, a configuration in which the source gases are independently supplied into the reaction vessel is also possible. It is. As the aluminum compound raw material, in addition to the raw materials exemplified above, AlH (CH ₃ ) ₂ , AlH (C ₂ H
₅ ) ₂ , Al (CH ₃ ) ₃ , Al (C ₄ H ₉ ) ₃ , Al
_{H 3 N (CH 3) 3} , (i-C 3 H 7) AlCl 2,
(N-C ₃ H _7), such as ₂ AlCl is applicable. Also,
Organic copper raw materials include Cu (acac) ₂ , Cu (hf
_{ac) 2, C 5 H 5} CuP (CH 3) 3, C 5 H 5 Cu
P (C ₂ H ₅ ) ₃ , (hfac) CuP (C
₂ H ₅ ) ₃ , (hfac) Cu (2-Butyne) and the like are applicable.

[0030]

As described above, according to the method for forming an aluminum alloy wiring according to the present invention, the pressure in each container is set higher than the pressure in the reaction vessel and lower than the atmospheric pressure. This is effective for increasing the feed rate of the raw material, and it is easy to form bubbles against the viscosity of the raw material, so that it is possible to stabilize the bubbling even with a high-viscosity liquid of 1000 cP or more.

Further, since the pressure of the other container is changed following the pressure of the one container, the ratio of the supply amounts of the two raw material gases can always be kept constant. Can always be uniformly controlled.

On the other hand, according to the aluminum alloy wiring forming apparatus, the pressure adjusting means for adjusting the pressure in each container, the pressure detecting means for detecting the pressure of each container, and the detection signal of each pressure detecting means are used. Since the control means for controlling the driving of each corresponding pressure adjusting means is provided, it is possible to carry out the method for forming the aluminum alloy wiring described above,
A similar effect is achieved.

Further, by providing the main control means for controlling each control means, the ratio of the supply amounts of the two source gases can always be kept constant.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an apparatus for forming an aluminum alloy thin film used in the present embodiment.

FIG. 2 is a chart showing the relationship between the number of runs and the film thickness.

FIG. 3 is a schematic configuration diagram showing a conventional alloy thin film forming apparatus.

[Explanation of symbols]

6a: container container (first container), 6b: container container (second container), 7a: raw material (aluminum compound raw material), 7b: raw material (copper compound raw material), 9: pressure gauge (pressure detecting means) ) And a pressure regulator (pressure regulating means), 10: pressure regulating valve (pressure regulating means), 11: reaction vessel, 14a,
14b: control device (control means) 20: main control device (main control means)

Continuation of front page (72) Inventor Yoshihiro Ota 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Engineering Co., Ltd. Technical Research Division (56) References JP-A-1-96922 (JP, A) JP-A-3 -47966 (JP, A) JP-A-2-170419 (JP, A) JP-A-5-21385 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/3205 H01L 21/205 H01L 21/285 301 H01L 21/365 H01L 21/768 H01L 21/3213 H01L 21/321

Claims (2)

(57) [Claims] 1. An aluminum compound raw material sealed in a first container is supplied with a carrier gas to generate an aluminum raw material gas, and a carrier gas is supplied to a copper compound raw material sealed in a second container to form a copper raw material gas. And supplying the aluminum source gas and the copper source gas generated in each of the containers together with the carrier gas into a reaction vessel,
In the method for forming an aluminum alloy wiring to form an aluminum alloy wiring by chemical vapor deposition, under a condition in which the pressure in each of the containers is set higher than the pressure in the reaction vessel and lower than the atmospheric pressure,
Pressure of either the first container or the second container
And following the pressure fluctuation in the one container
A method for forming an aluminum alloy wiring, wherein the pressure in the other container is changed . 2. A first material containing an aluminum compound raw material.
A container, a second container enclosing a copper compound raw material, and a reaction vessel in which each raw material gas generated in the first and second containers is introduced together with a carrier gas to form aluminum alloy wiring by chemical vapor deposition In the apparatus for forming an aluminum alloy wiring, the forming apparatus is further provided in a source gas supply line between the reaction vessel and each of the containers, and the source gas flowing through the source gas supply line. Pressure adjusting means for adjusting the pressure in each of the housings by adjusting the flow rate (or conductance); pressure detecting means for detecting the pressure in each of the housings; and a detection signal from each of the pressure detecting means. And control means for controlling the driving of the corresponding pressure adjusting means, and accommodation of either the first container or the second container.
The pressure of the other container changes following the fluctuation of the body pressure.
Main control means for controlling each of the control means as described above.
A device for forming an aluminum alloy wiring.