JPH08279558A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE: To provide a method which forms a titanium nitride film having together good barrier properties and a high reliability to a wiring at a temperature lower than the melting point of aluminium and can decrease the concentration of chlorine being remained in the titanim nitride film. CONSTITUTION: A titanium nitride film is deposited so that the nitride film is formed into a desired film thickness by a CVD method and thereafter, a plasma irradiation treatment is performed in an atmosphere containing at least one kind of the gas of hydrogen, nitrogen and ammonia gases to make the radicals of these gases produce and the concentration of chlorine being remained in the nitride film is reduced by these radials 15. It is also possible that the deposition of this titanium nitride film and the plasma irradiation treatment are repeated to obtain a titanium nitride film of a desired film thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device having a metal wiring containing a titanium nitride film.

[0002]

2. Description of the Related Art As semiconductor devices are being miniaturized and highly integrated, problems such as spikes of aluminum, which is a wiring material, in a diffusion layer and deposition of substrate silicon on aluminum wiring are solved in a shallow diffusion layer. Therefore, a diffusion barrier layer (called a barrier metal) is inserted in the contact portion between the aluminum film or aluminum alloy layer and the diffusion layer formed on the surface of the silicon substrate.

The most promising barrier metal at present is titanium nitride (TiN). The reason for this is that this titanium nitride has excellent barrier properties and relatively low resistance, as well as the reliability of wiring such as electromigration resistance and stress migration resistance due to the formation of laminated wiring with aluminum. It has been found that it also plays a role of improving. The formation of the titanium nitride film as a barrier metal in this way is described in, for example, Japanese Patent Laid-Open Nos. 3-214734 and 6-196482. Titanium nitride films have heretofore been obtained by reactive sputtering, or by sputtering deposition of titanium and then nitriding with ammonia or nitrogen. Recently, in order to form a titanium nitride film having a sufficient thickness at the bottom of the contact hole, studies have been made on film formation by a sputtering method using a collimator. However, if the aspect ratio of the contact hole becomes larger in the future, the sputtering method using a collimator will reach its limit, and it is considered that the CVD method, which enables conformal film formation inside the fine hole, will become the mainstream.

In the CVD method for forming a titanium nitride film, the most promising raw material at present is titanium tetrachloride. The titanium nitride film obtained by using such an inorganic raw material not only has a low resistance, that is, a low impurity film as compared with a titanium nitride film formed by an organic raw material, By optimizing, even for fine holes with an aspect ratio of 5 or more, almost 10
It has been reported that 0% coverage is achieved (eg IDEM Conf. Proc., Dec., 1990, p.47).

[0005]

One of the problems in forming a titanium nitride film by the CVD method in a system using titanium tetrachloride is to reduce the concentration of chlorine taken into the titanium nitride film. This is because when the titanium nitride film having a high chlorine concentration has a high resistance and the aluminum alloy formed on the titanium nitride film is easily corroded by chlorine, when the chlorine concentration in the titanium nitride film is high, This is because it affects the reliability of the wiring.

In order to solve the above-mentioned problems, VMIC Con
ference, June, 1992, p.295 discloses performing RTA in an ammonia atmosphere. However,
With this method, the melting point of aluminum is 750 ° C (660 ° C)
If a higher temperature is required and aluminum is already included in the lower side, for example, when the first metal wiring layer is aluminum wiring, when the method is applied to the contact hole, the already formed aluminum is formed. Wiring is 75
There is a problem that this method cannot be applied because it cannot withstand a high temperature of 0 ° C. Further, even when it is applied only as a barrier metal to the contact hole, it is desirable to carry out the metal wiring forming process at the lowest possible temperature, considering the recent shallow diffusion layer.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to process a titanium nitride film having both barrier properties against a semiconductor substrate and high reliability of wiring at a temperature lower than the melting point of aluminum wiring. Nevertheless, it is an object of the present invention to provide a method for manufacturing a semiconductor device which has a sufficiently low impurity concentration and can be formed with low resistance.

[0008]

According to the method of manufacturing a semiconductor of the present invention, in manufacturing a semiconductor device having a metal wiring including a titanium nitride film, the titanium nitride film is chemically vaporized until a desired film thickness is obtained. Concentration of chlorine remaining in the titanium nitride film after a film formation step of depositing by a phase growth method and subsequent treatment with radicals of these substances generated in an atmosphere containing at least one of hydrogen, nitrogen and ammonia And a post-treatment step for reducing Furthermore, the method for manufacturing a semiconductor device according to the present invention is intended to manufacture a semiconductor device having a metal wiring containing a titanium nitride film.
A film forming step of depositing the titanium nitride film by a chemical vapor deposition method so as to be thinner than a desired film thickness, and (b) subsequently formed in an atmosphere containing at least one of hydrogen, nitrogen and ammonia. A post-treatment step of reducing the chlorine concentration remaining in the titanium nitride film by treating with radicals of these substances, (c) the film forming step (a)
And a step of repeating the post-treatment (b) until the film thickness of the titanium nitride film reaches a desired film thickness. In such a method of manufacturing a semiconductor device according to the present invention, the post-treatment step is particularly preferably plasma treatment.

[0009]

In the method of manufacturing a semiconductor device according to the present invention described above, since all the steps can be performed at a temperature lower than the melting point of aluminum when forming a titanium nitride film by the CVD method, the barrier for the first layer wiring is formed. Not only the titanium nitride film as the metal but also the aluminum wiring in the lower layer can be used to form the titanium nitride film by the CVD method with excellent coverage.
At the same time, plasma treatment in an atmosphere containing at least one of hydrogen, nitrogen, and ammonia can reduce the concentration of chlorine taken into the titanium nitride film, which may cause corrosion of the aluminum film. Also disappears. That is, the concentration of impurities remaining in the titanium nitride film can be sufficiently reduced by the process at a temperature lower than the melting point of aluminum.

[0010]

EXAMPLE In the first example of the method for manufacturing a semiconductor device according to the present invention, a silicon substrate is used as a semiconductor substrate, and TiCl ₄ / NH ₃ / H ₂ is used as a raw material system for a CVD-TiN film. A titanium nitride film was formed to a film thickness of 300 Å under the film forming conditions shown in. In this table, SCCM indicates the flow rate under standard conditions of 0 ° C. and 1 atm by CM ³ .

[Table 1] It was confirmed that the titanium nitride film formed under such conditions can be conformally formed even on a step. Furthermore, it was also confirmed that when the titanium nitride film formed in this manner was applied to the contact, good barrier properties were exhibited. It is considered that this is because the titanium nitride layer is conformally formed, so that the titanium nitride layer having a sufficient film thickness is also formed at the bottom of the contact hole.

In the present invention, after the titanium nitride layer is formed by the CVD method, plasma treatment is performed in an atmosphere of at least one of hydrogen, nitrogen and ammonia. To confirm the effect of the present invention, Plasma treatment was performed by using argon as a gas species in addition to hydrogen, nitrogen, and ammonia. The conditions for this plasma treatment are that the total pressure is 1 Torr.
The RF power was 250 W, the silicon substrate was heated to 500 ° C., and the treatment was performed for 6 minutes. Further, for comparison, the total pressure and the substrate temperature were the same, and the heat treatment was performed for the same time without generating plasma. The sample was prepared by using a multi-chamber type apparatus having both a titanium nitride layer deposition chamber and a plasma processing chamber. In such a device, two process chambers are connected to a transfer chamber for transferring a sample through a gate valve. Since the transfer chamber is constantly evacuated, it can be continuously performed without exposing the silicon substrate to the atmosphere between the two processes of forming the titanium nitride layer and plasma treatment.

The chlorine concentration in the film was examined for several samples treated as described above. This was done by SIMS analysis. Chlorine was mixed in the titanium nitride film as deposited by the CVD method at a concentration of about 3 atom%. Table 2 shows the chlorine concentration of a sample obtained by subjecting such a titanium nitride film to plasma treatment and the chlorine concentration of a sample subjected to a heat treatment without generating plasma.

[Table 2]

From these results, it was found that the plasma treatment with hydrogen, nitrogen and ammonia gas is effective in reducing the residual chlorine concentration in the titanium nitride film. on the other hand,
It was found that the plasma treatment with argon gas was not so effective in reducing the chlorine concentration. Furthermore, it was also found that in the case of simple heat treatment without using plasma, there is almost no chlorine reduction effect except in the ammonia atmosphere. From these, it was found that radicals generated in hydrogen plasma, nitrogen plasma, and ammonia plasma, that is, hydrogen radicals, nitrogen radicals, and ammonia radicals, act to reduce the residual chlorine concentration in the titanium nitride film. It was In the case of heat treatment that does not use plasma, it is considered that the reason why only ammonia gas is effective in reducing the chlorine concentration is that ammonia is decomposed at relatively low temperature with only thermal energy to generate radicals. The effect of reducing the chlorine concentration is not sufficient due to the low temperature.

An aluminum film is formed on the titanium nitride film formed as described above by a sputtering method at 3000
After depositing to a thickness of Å, a line-patterned Al / TiN laminated film was left in the clean room for 24 hours in the atmosphere to examine the corrosion state of the aluminum film. Corrosion was observed in the titanium nitride film which was not subjected to any post-treatment, the aluminum film on the titanium nitride film which was not subjected to plasma treatment and the aluminum film on the titanium nitride film which was subjected to argon plasma treatment. On the other hand, no corrosion was observed in the aluminum film on the titanium nitride film plasma-treated in the atmosphere of hydrogen, nitrogen and ammonia. Such a result can be explained by the difference in the residual chlorine concentration in the titanium nitride film. That is, the residual chlorine concentration in the titanium nitride film that has not been post-treated is large enough to cause corrosion of aluminum, and the post-treatment (heat treatment and argon plasma treatment) with a small chlorine concentration reduction effect is performed. Can not suppress the corrosion of aluminum. On the other hand, in the sample subjected to the plasma treatment in hydrogen, nitrogen and ammonia, the chlorine concentration remaining in the titanium nitride film was extremely low, and it was found that the corrosion of aluminum was effectively prevented.

A second method of manufacturing a semiconductor device according to the present invention.
In the example, the following experiment was further conducted on hydrogen plasma, nitrogen plasma, and ammonia plasma treatments that have a high chlorine concentration reducing effect. That is, first CV
After forming the D-TiN film to a film thickness of 100 Å, perform plasma treatment for 2 minutes in each atmosphere, and repeat the same process 3 times to finally obtain a titanium nitride film with a film thickness of 300 Å. Formed. The film forming conditions and the plasma processing conditions in this case were the same as described above. Therefore, the total plasma processing time is 6 minutes. The chlorine concentration in the titanium nitride film thus formed is shown as three treatments in Table 3. The one-time treatment means the residual chlorine concentration of the titanium nitride film obtained in the above-mentioned first embodiment in which the film formation by CVD and the plasma treatment are performed only once.

[Table 3]

Despite the same film thickness and the same plasma processing time, it is better to perform the film formation and the plasma treatment in three steps than to form the titanium nitride film having the desired film thickness in one time. It was confirmed that the residual chlorine concentration was low. This indicates that the effect of the plasma treatment is large near the surface of the titanium nitride film and diminishes in the thickness direction of the film. In fact, SIMS
The profile of the titanium nitride film subjected to plasma treatment showed a remarkable decrease in chlorine concentration near the surface as compared with the titanium nitride film not subjected to plasma treatment. It was confirmed that the difference between the two was small.

The present invention is not limited to the above-mentioned embodiments, but various modifications and variations are possible. For example, although TiCl ₄ / NH ₃ / H ₂ was selected as the raw material system for the CVD-TiN film formation in the above-mentioned embodiments, other titanium halides (for example, titanium tetrabromide) are used as the raw material source for titanium. However, an organic raw material (for example, tetradimethylaminotitanium) may be used. Further, the nitrogen source is not limited to NH ₃ . However, considering the coating shape at the stepped portion, the raw material system of the above-mentioned embodiment or TiCl 2 which can obtain a conformal shape is used.
_It is desirable to adopt ₄ / NH ₃ .

Further, the gas flow rate and total pressure in the plasma treatment are not limited to those in the above-mentioned embodiment, and any condition may be selected as long as the coating shape is excellent. Further, the film forming temperature is not limited to 500 ° C., and can be arbitrarily selected within the range of 400 to 500 ° C. The process of exceeding 500 ° C is not preferable because the reliability of the wiring is impaired when aluminum wiring is already present in the base. When the film is formed at a temperature lower than 400 ° C, the residual chlorine concentration becomes extremely high, and the chlorine concentration cannot be sufficiently reduced by the subsequent plasma treatment, which is not preferable.

Further, in the above-mentioned embodiment, the thermal CVD method is used for forming the titanium nitride film, but if it is the CVD method, the plasma CVD method or the optical CVD method can be used. However, it is most preferable to use the thermal CVD method in consideration of the coating shape at the step portion. Further, in the above-described embodiments, the plasma treatment using radicals generated by RF discharge is adopted as the post-treatment, but plasma treatment using DC discharge or ECR discharge may be used. Further, as described above, since it is the radical species that contribute to the reduction of the chlorine concentration, it is not necessary to use the plasma treatment as long as it produces radicals. For example, post-treatment using radical production by UV irradiation is adopted. You can also do it. However, in consideration of the effect of reducing the chlorine concentration and the ease of the process, plasma treatment is preferable.

Further, although the post-treatment temperature is set to 500 ° C. which is the same as the film forming temperature in the above-mentioned embodiment, the post-processing temperature is not limited thereto and may be arbitrarily selected as long as it is 500 ° C. or less. In this case, if the temperature exceeds 500 ° C., the reliability of the wiring is impaired if aluminum wiring is already present in the base, as is the case with the substrate temperature at the time of film formation, which is not preferable.
On the other hand, although the lower limit of the temperature is not particularly limited, it is desirable that the temperature is as high as possible in order to efficiently reduce the chlorine concentration. Regarding the atmosphere when performing the plasma treatment, in the above-mentioned embodiment, one kind of gas among hydrogen, nitrogen and ammonia was used, but if at least any one of hydrogen, nitrogen and ammonia is contained, It is also possible to use a mixed gas of a plurality of gases. Further, in the above-described second embodiment, the titanium nitride film forming step and the subsequent plus-plus treatment are repeated three times, and the respective film forming conditions and the plasma processing conditions are all the same. Needless to say, it can be set arbitrarily and the processing conditions for each time can also be set arbitrarily.

[0021]

As described above, according to the method for manufacturing a semiconductor device of the present invention, it is possible to form a titanium nitride film having excellent step coverage and a sufficiently low impurity concentration at a temperature equal to or lower than the melting point of aluminum. it can. As a result, it is possible to provide a semiconductor device having a highly reliable metal wiring in which the barrier property is sufficiently ensured and the aluminum film is not corroded. Further, since the titanium nitride film can be formed even when the aluminum film is already formed as the lower layer, the applicable range of the CVD-TiN film forming technique can be expanded.

Claims (3)

[Claims] 1. When manufacturing a semiconductor device having a metal wiring including a titanium nitride film, a film forming step of depositing the titanium nitride film by a chemical vapor deposition method to a desired film thickness, and And a post-treatment step of reducing the concentration of chlorine remaining in the titanium nitride film by treating with radicals generated in an atmosphere containing at least one of hydrogen, nitrogen and ammonia. Device manufacturing method. 2. In manufacturing a semiconductor device having a metal wiring containing a titanium nitride film, (a) a step of depositing the titanium nitride film by a chemical vapor deposition method so as to be thinner than a desired film thickness, b) a post-treatment step of subsequently treating with radicals generated in an atmosphere containing at least one of hydrogen, nitrogen and ammonia to reduce the concentration of chlorine remaining in the titanium nitride film;
(C) A method of manufacturing a semiconductor device, comprising: repeating the steps (a) and (b) until the film thickness of the titanium nitride film reaches a desired film thickness. 3. The method for manufacturing a semiconductor device according to claim 1, wherein the post-treatment step is a plasma treatment in an atmosphere containing at least one of hydrogen, nitrogen and ammonia.