JPH06256953A - Gas introducing method for tin-cvd and gas introducing mechanism - Google Patents

Abstract

PURPOSE:To provide a gas introducing method for TiN-CVD without deposition of an impurity and enabling to form a uniform film on a base plate, and a gas introducing mechanism. CONSTITUTION:A reactive gas consisting of a titanium compound and a reactive gas consisting of a nitrogen compound are introduced from an outside of a reaction container by separating them till a gas ejector 3 confronted to the base plate 8, and also the reaction gas consisting of the titanium compound is kept at a higher temp. than the dew point temp. The gas introducing mechanism for practicing this method is constituted of connecting a reaction gas source outside the reaction vessel with the gas ejector 3 provided by being confronted to the base plate 8 in the reaction vessel via a double pipe (which is composed of an inside pipe 1 and an outside pipe 2) and winding a sheath heater 7 on the inside pipe 1 of the double pipe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a mechanism for introducing a titanium compound gas and a nitrogen compound gas into a reaction vessel when a TiN (titanium nitride) thin film is formed by a CVD (Chemical Vapor Deposition) method.

[0002]

2. Description of the Related Art In a highly integrated IC, in order to improve the reliability of the contact electrode portion, Ti as a diffusion barrier is used.
The formation of the N layer has become an essential condition. The formation of the TiN layer is considered to be an effective method for forming a film by the CVD method as the wiring becomes finer.

Conventionally known CVD methods include the following techniques. That is, 1) there is a technique for forming a TiN film by a CVD method using an apparatus as shown in FIG. NH ₃ gas 1
1 and TiCl ₄ gas 12 are introduced into reaction vessel 15 through conduits 13 and 14, respectively. For NH ₃ gas,
It goes through the container 16 for the purpose of diffusion toward the substrate 19 from the slit 18 formed in the container 16. On the other hand, the TiCl ₄ gas 12 is ejected from a pipe 17 facing the substrate 19 downstream of the NH ₃ gas. N
The H ₃ gas 11 and the TiCl ₄ gas 12 are mixed on the substrate 19, and TiN is deposited on the surface of the substrate 19 (for example, 19
Published in March 1989, Journal of the Electrochemical Soc
society, Vol. 36, No. 3, pp. 882-883). 2) There is a technique for forming a TiN film by a CVD method using an apparatus as shown in FIG. NH ₃ gas 2
1 and TiCl ₄ gas 22 are introduced into a drum-shaped container 26 installed in a reaction container 25 through conduits 23 and 24, respectively. The container 26 has a plurality of small holes formed on the surface 27 facing the substrate 28. Both reaction gases mixed in the container 26 are ejected through the small holes, and TiN is deposited on the surface of the substrate 28 (for example, a special Kaihei 3-64473). 3) There is a technique for forming a film of SiO ₂ by the CVD method using the apparatus shown in FIG. The gas to be introduced is
It is mainly O ₃ + O ₂ gas 31 and TEOS gas 32. Both reaction gases are separately introduced into the dispersion head 36 in the reaction container 35. 38 is an exhaust pipe.
Both reaction gases are ejected in layers from the grooves 37 of the dispersion head 36, and are mixed and directed toward the substrate 39 to deposit SiO ₂ on the surface of the substrate 39 (eg, 1989).
Annual Issue, Electrochemistry, Vol. 56, No. 7, pp. 527-532). 4) There is a technique for forming a film of SiO ₂ by the CVD method using the apparatus shown in FIG. The gas to be introduced is the excited oxygen gas 41 generated by thermal plasma and TE.
The OS gas 42. The TEOS gas 42 is introduced into a gas blower 46 having a plurality of dispersion plates 44 for the purpose of diffusion. The gas blower 46 is provided with a plurality of pipes 45 arranged so as to face the substrate 47, and the excited oxygen gas 41 is ejected through the pipes 45. Both reaction gases join at the tip of the gas blower 46.
Heading toward the substrate 47 while combining, Si on the surface of the substrate 47
O ₂ is deposited (for example, JP-A-3-122281).

[0004]

The low pressure CVD method (LPC
As a basic point to be noted in the formation of the TiN film by the VD method), since TiCl ₄ gas is a liquefied gas, it is necessary to prevent the gas temperature from lowering during the transfer so that it does not solidify after being vaporized. When mixed TiCl ₄ gas and NH ₃ gas at point and -30 to 180 ° C., TiCl ₄ · 2NH3 instead TiN is generated, become yellow powder, so to form impurity in the reaction vessel, it There are some points to avoid (eg, February 1991, Journal of the Electrochemical Society, 13th
8: No. 2, pp. 500-505).

That is, impurities are deposited on the transfer path of the reaction gas, the surface of the reaction gas which is in contact with the reaction gas before reaching the substrate, the exhaust path, and the like. Therefore, the reaction becomes unstable, and it becomes necessary to frequently remove impurities in the reaction vessel. Also, VL
In forming TiN in SI manufacturing, the film forming rate, the film thickness distribution, and the uniformity of the film quality become more important as the diameter of the substrate becomes larger. However, the above factors lead to a decrease in their reliability. .

In the above-mentioned prior art 1), TiCl ₄
It is considered that the reaction with the NH ₃ gas is decided depending on the diffusion of the gas, and the film quality and the film thickness become nonuniform on the substrate corresponding to the central part and the peripheral part of the TiCl ₄ gas jet.

In 2), the gas mixed in the drum-shaped container has already reacted before ejecting from the container to deposit impurities in the mixing container.

In 3), since the gases adjoin each other and go straight toward the substrate, the mixing proceeds only by the lateral diffusion of both gases. Therefore, the chemical composition is not uniform, and it is difficult to obtain a uniform film.

In 4), since both gases are vigorously mixed in the vicinity of the ejection portion, an impurity precipitation reaction may occur.

[0010]

The present invention has been made in view of the above problems, and is free from precipitation of impurities.
Another object of the present invention is to provide a TiN-CVD gas introduction method and a gas introduction mechanism capable of forming a uniform film on a substrate.

The TiN-based alloy of the present invention which achieves the above objects.
The gas introduction method for CVD is a gas introduction method of the CVD method in which a titanium compound and a nitrogen compound, which are reaction gases, are transferred, both reaction gases are mixed near the substrate, and a CVD reaction is caused on the substrate to obtain a TiN thin film. In the above method, the reaction gas is separately introduced from the outside of the reaction container to a gas ejector facing the substrate, and the reaction gas composed of a titanium compound is kept at a temperature higher than the dew point temperature.

In the TiN-CVD gas introduction mechanism of the present invention, the titanium gas and the nitrogen compound, which are reaction gases, are transferred, both reaction gases are mixed in the vicinity of the substrate, and C
In a gas introduction mechanism of a CVD method for causing a VD reaction to obtain a TiN thin film, a reaction gas source outside the reaction container and a gas ejector installed in the reaction container so as to face the substrate are connected through a double pipe. The inner tube of the double tube is provided with heating means.

In order to uniformly mix the two reaction gases to reach the substrate, the gas ejector communicates an annular pipe body having a plurality of small holes facing the substrate with the inner pipe of the double pipe. At the same time, the outside of the pipe body and the outer pipe of the double pipe are made to communicate with each other, and the reaction gas consisting of the titanium compound is wrapped with the reaction gas consisting of the nitrogen compound so that the gas is ejected from the gas ejector. Is desirable.

[0014]

According to the TiN-CVD gas introduction method of the present invention, the reaction gas consisting of the titanium compound and the reaction gas consisting of the nitrogen compound can be completely separated and transferred until just before the CVD reaction on the surface of the substrate. it can. Further, the reaction gas composed of the titanium compound can be transferred without dew condensation. Therefore, the reaction gas can be transferred in a good condition, and since it does not come into contact with anything until it reaches the substrate after being combined by being ejected from the gas ejector, a reaction other than the intended reaction may occur. Therefore, the generation of impurities can be eliminated.

Further, according to the TiN-CVD gas introduction mechanism of the present invention, the above-mentioned effects can be obtained, and the space occupied by the gas introduction pipe can be reduced. By enclosing the gas with the reaction gas composed of a nitrogen compound, both reaction gases can be combined completely and uniformly, and the film formation on the substrate can be made uniform.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.

TiC as a reaction gas composed of a titanium compound
NH ₄ is used as a reaction gas composed of a nitrogen compound by using l ₄ gas.
We decided to use ₃ gases. Since TiCl ₄ gas is a liquefied gas, a heat retention mechanism (up to 80 ° C.) is required to prevent dew condensation during transfer under the reduced pressure required for the CVD reaction which is the object of the present invention. Also, TiCl ₄ gas and N
In the reaction with H ₃ gas, if combined at a temperature of 180 ° C. or lower, TiCl ₄ + 2NH ₃ ← → TiCl ₄ .2NH
₃ (Yellow Solid) has a property of causing an impurity generation reaction.

Therefore, the gas introduction mechanism is constructed as shown in FIGS. Inner tube 1 and outer tube 2 are made of stainless steel (SUS3
It is a coaxial double tube made in 16). Generally T
The flow rate ratio of the reaction gas in forming the iN film is TiCl ₄ :
Since NH ₃ = 1: 10 to 100, Ti is used for the inner tube 1.
Cl ₄ gas and NH ₃ gas 2 were introduced into the outer tube 2. A sheath heater 7 covered with a corrosion resistant sheath is wound around the inner tube 1 so that the inner tube 1 can be heated to 80 ° C. or higher by electric power from an external heater power source 10.
Make sure that the iCl ₄ gas does not condense in the inner tube 1.

At the tip of the coaxial double tube consisting of the inner tube 1 and the outer tube 2, a gas ejector 3 facing the substrate 8 is connected in series. The gas ejector 3 is composed of an inverted funnel-shaped cover 4 attached to the outer pipe 2 and annular pipe bodies 6 arranged inside the cover 4 concentrically. 6, 6
And the inner pipe 1 are communicated with each other through branching branch pipes 4, 4, 5 and 5, and a large number of small holes 9, 9 are opened at equal intervals in a side wall of the pipe body 6, 6 facing the substrate 8. To do.

Using the gas introduction mechanism as described above, the inner tube 1 is maintained at a temperature of 80 ° C. or higher, and TiCl ₄ gas and NH ₃ gas are introduced. The TiCl ₄ gas is guided to the pipes 6, 6 without dew condensation in the inner pipe 1, and the small holes 9,
It is jetted from 9 toward the substrate 8 (arrow a). Tube 6, 6
Although the sheath heater 7 is not wound around, the radiant heat from the substrate 8 (300 to 400 ° C.) to be heated and the heat conduction from the inner tube 1 are considered not to lower the temperature below 80 ° C. .

On the other hand, NH ₃ gas is introduced through the outer pipe 2, reaches the gas ejector 3 so as to wrap the inner pipe 1, and reaches the substrate 8 so as to wrap the TiCl ₄ gas ejected from the small holes 9, 9. Squirt out (arrow b).

However, TiCl ₄ gas and NH ₃ gas are
After jetting, they are mixed uniformly and reach the substrate 8 without contacting any other member. Therefore, only pure TiN forming reaction occurs on the heated substrate 8, and a high-purity TiN film is uniformly formed over the entire surface of the substrate 8.

[0023]

As described above, according to the gas introduction method of the present invention, the reaction gas is introduced separately to the gas ejector facing the substrate, and the reaction gas consisting of the titanium compound is condensed. Since I did not do so, I got the required C on the board
There is an effect that a VD reaction can be stably caused.

The reaction gas composed of the titanium compound is wrapped with the reaction gas composed of the nitrogen compound and ejected from the gas ejector, so that the reaction gas is uniformly mixed and a uniform film formation can be achieved.

According to the gas introduction mechanism of the present invention,
Since the reaction gas can be introduced to the gas ejector through the double pipe, in addition to the same effect as described above, there is an effect that the space occupied by the mechanism for introducing the gas can be reduced. Since there is no member interposed between the gas ejector and the substrate, the ejected reaction gas can reach the substrate without coming into contact with anything, and the high purity TiN film can be formed without depositing impurities. There is.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of the present invention.

FIG. 2 is a bottom view of the embodiment as well.

FIG. 3 is an explanatory view of a conventional gas introduction mechanism.

FIG. 4 is an explanatory view of another conventional gas introducing mechanism.

FIG. 5 is an explanatory view of another conventional gas introduction mechanism.

FIG. 6 is an explanatory view of still another conventional gas introducing mechanism.

[Explanation of symbols]

 1 Inner Tube 2 Outer Tube 3 Gas Ejector 4 Cover 5 Branch Branch Tube 6 Tubular Body 7 Sheath Heater 8 Substrate 9 Small Hole

Claims (4)

[Claims] 1. A gas introduction method of a CVD method, wherein a titanium compound and a nitrogen compound, which are reaction gases, are transferred, both reaction gases are mixed near a substrate, and a CVD reaction is caused on the substrate to obtain a TiN thin film. The TiN-CVD is characterized in that the reaction gas is separately introduced from the outside of the reaction container to a gas ejector facing the substrate, and the reaction gas composed of a titanium compound is kept at a temperature higher than the dew point temperature.
Gas introduction method. 2. The reaction gas is such that a reaction gas composed of a titanium compound is wrapped with a reaction gas composed of a nitrogen compound,
The TiN-CV according to claim 1, which is ejected from a gas ejector.
Gas introduction method for D. 3. A gas introduction mechanism of a CVD method, in which a titanium compound and a nitrogen compound, which are reaction gases, are transferred, both reaction gases are mixed near a substrate, and a CVD reaction is caused on the substrate to obtain a TiN thin film. A reaction gas source outside the reaction vessel and a gas ejector installed inside the reaction vessel so as to face the substrate are connected through a double tube, and a heating means is provided in the inner tube of the double tube. A gas introduction mechanism for TiN-CVD. 4. The gas ejector connects an annular pipe having a plurality of small holes facing the substrate with an inner pipe of the double pipe, and connects the outside of the pipe with an outer pipe of the double pipe. The gas introduction mechanism for TiN-CVD according to claim 3, which is constituted by