JPH06302601A - Fabrication of semiconductor device - Google Patents

Abstract

PURPOSE:To improve the EM and SM resistances of a wiring by rendering the wiring to a constant-temperature leaving processing, the wiring possessing a bump structure and comprising an Al alloy containing a predetermined amount of Cu and further containing Si in concentration less than the limit of a solid solution to Al at a constant-temperature leaving processing temperature. CONSTITUTION:A semiconductor substrate 1 is thermally oxidized and hereby an oxide film 2 is formed on the semiconductor substrate 1. A wiring 3 comprising a fine Al-Cu alloy is formed on the oxide film 2. The wiring 3 possesses a bump structure and is yielded by rendering an Al alloy wiring to a constant- temperature leaving processing at a temperature lower than the limit of a solid solution of Cu with respect to Al, i.e., at a temperature lower than 300 deg.C. A passivation film 4 is deposited on the wiring 3, and is thereafter rendered to an alloy processing to construct a semiconductor device. Hereby, an Al-Cu alloy is effectually separated without separation of Si in the wiring. Thus, EM and SM resistances of the wiring are sharply improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to improving the electromigration resistance (hereinafter referred to as "EM resistance") and stress migration resistance (hereinafter referred to as "SM resistance") of wiring. To a method for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art Heretofore, elements have been miniaturized with the miniaturization and high integration of semiconductor devices. For this reason, the current density of the wiring is increased, and local disconnection and increase in resistance are likely to occur, and it is increasingly required to improve the EM resistance. This electromigration is a phenomenon in which electrons collide with metal ions to generate voids, which leads to disconnection.

Therefore, as one method for improving the EM resistance of wiring, for example, an Al alloy (hereinafter, referred to as "Cu") in which a desired amount of copper (hereinafter, referred to as "Cu") is added to aluminum (hereinafter referred to as "Al") A method of using "Al-Cu alloy" as a wiring material is introduced. This Al-
Wiring made of Cu alloy is subjected to desired heat treatment,
Al-Cu alloy is deposited on the grain boundaries of the wiring film,
By using this as a void sink, EM resistance is improved. Similarly, instead of Cu,
A desired amount of scandium (hereinafter referred to as "Sc"), palladium (hereinafter referred to as "Pd"), hafnium (hereinafter referred to as "
The same effect can be obtained by using an Al alloy added with “Hf”) as a wiring material.

[0004]

However, in the manufacturing process of a semiconductor device, after performing the desired heat treatment,
For example, since a heat treatment process at a temperature of 400 ° C. or higher is performed in an assembly process or the like, for example, the above Al—Cu
There is a problem that the system alloy becomes solid-solved again in the wiring metal, and it is difficult to sufficiently deposit the Al—Cu system alloy at the grain boundaries of the wiring.

Therefore, in order to solve this problem, for example, after the final heat treatment step performed at a temperature of 400 ° C. or higher, an incubating treatment (aging treatment) is performed at a temperature not higher than the solid solubility limit of copper in Al. Therefore, precipitation of Al-Cu alloy is promoted (for example, Japanese Patent Application No. 4-349).
382). Further, in recent years, the miniaturization of semiconductor devices has advanced more and more, and the width of wiring has become 1.2 μm or less. Here, since the diameter of the grains existing in the wiring is about 2 μm, when the wiring width is narrower than that, the grains cannot exist in the wiring while maintaining their shape, and The bamboo structure is as shown in FIG. The wiring having the bamboo structure has a problem of improving the EM resistance but lowering the SM resistance as compared with the conventional wiring having grains as shown in FIG.

In the above-mentioned constant temperature treatment step, no effect was disclosed when the width of the wiring was smaller than the grain diameter and a bamboo structure was formed in the wiring. In addition, even if this incubating process is performed, the wiring made of the Al alloy is referred to as “S” (hereinafter, “S
i)) is contained in the wiring, the actual wiring width is narrowed, a local temperature rise occurs during energization, and the EM resistance is significantly reduced. .

An object of the present invention is to solve such a conventional problem, and to significantly improve the EM resistance and SM resistance of a wiring made of a fine Al alloy having a bamboo structure. It aims at providing the manufacturing method of.

[0008]

In order to achieve this object, the present invention provides a semiconductor device in which a wiring made of an Al alloy containing Cu is subjected to an incubating treatment at a temperature below the solid solubility limit of Cu in Al. In the manufacturing method of (1), a predetermined amount of Cu is contained, and Si is Al at the isothermal treatment temperature.
A method for manufacturing a semiconductor device is characterized in that the above-mentioned constant temperature standing treatment is performed on the wiring made of an Al alloy having a concentration not higher than the solid solubility limit and having a bamboo structure.

Further, the wiring made of an Al alloy containing any one of Sc, Pd, and Hf is allowed to stand at a temperature below the solid solubility limit of any of Sc, Pd, and Hf contained in the Al with respect to Al. A method for manufacturing a semiconductor device, wherein a predetermined amount of any one of Sc, Pd, and Hf is contained, Si is contained at a concentration lower than a solid solution limit with respect to Al at the isothermal treatment temperature, and a bamboo structure is provided. A method for manufacturing a semiconductor device is provided, in which the wiring made of an Al alloy is subjected to the constant temperature standing treatment.

Then, the present invention provides a method for manufacturing a semiconductor device, characterized in that the incubating treatment is performed at 300 ° C. or lower.

[0011]

According to the method of manufacturing a semiconductor device of the present invention, a predetermined amount of Cu is contained, and Si is contained at a concentration not higher than the solid solution limit with respect to Al at the isothermal treatment temperature, and an Al alloy having a bamboo structure is used. Since the resulting wiring is subjected to an isothermal treatment at a temperature not higher than the solid solubility limit of Cu in Al, Si does not precipitate in the wiring. Therefore, since the substantial wiring width is not narrowed, the EM resistance is not reduced.

Further, since the Al-Cu alloy can be effectively deposited on the grain boundaries of the fine wiring having the bamboo structure, the EM resistance and SM resistance of the wiring can be greatly improved. . Then, instead of Cu, by performing the isothermal treatment on the wiring made of an Al alloy containing any one of Sc, Pd, and Hf in the same manner, the Al—Sc alloy at the grain boundary of the wiring is also subjected. , Al-Pd-based alloys and Al-Hf-based alloys can be effectively deposited, so that the EM resistance and SM resistance of the wiring can be significantly improved.

By performing the incubating treatment at 300 ° C. or lower, the Al—Cu alloy can be further effectively deposited on the grain boundaries of the fine wiring having the bamboo structure.

[0014]

Embodiments of the present invention will now be described with reference to the drawings. 1A and 1B are partial cross-sectional views showing a part of the manufacturing process of the semiconductor device according to the embodiment of the invention. In the step shown in FIG. 1A, thermal oxidation is performed on the semiconductor substrate 1 which has been subjected to a desired treatment, and the film thickness is reduced to 0.
An oxide film 2 of about 6 μm is formed.

Then, in the step shown in FIG.
A wiring film made of an Al-Cu alloy having a composition of Al = 99.5% and Cu = 0.5% is formed on the oxide film 2 formed in the step (1) by a sputtering method to have a thickness of about 0.8 μm. After being vapor-deposited with a film thickness of, the wiring 3 is patterned to form the wiring 3 made of a fine Al—Cu alloy having a wiring width of about 0.8 to 1.2 μm. At this time, grains cannot exist while maintaining their shape in the wiring 3 made of Al—Cu alloy, and the wiring has a bamboo structure as shown in FIG.

Next, the wiring 3 made of this Al--Cu alloy
After depositing the passivation film 4 by CVD (Chemical Vapor Deposition) method, 400 ° C., 3
Alloy processing for 0 minutes is performed. This alloying process is a process generally performed during the manufacturing process of a semiconductor device in order to obtain the stabilization of the transistor. Then, FIG. 1 (2)
The wafer obtained in step 1 is subjected to a desired process, a ceramic package is applied, and then an incubating process (aging process) is performed at 250 ° C. for 10 hours.

Through the above steps, a semiconductor device according to this example was obtained. Next, the wiring width is 0.8 μm, 1.2 μm, 2.4 μm and 4.8 μm in the same manner as in the above embodiment.
A sample (invention product) in which the wiring 3 made of Al-Cu alloy of m was formed. In addition, as a comparison, the wiring width is 0.8 μm, 1.2 μm, 2.4 μm and 4.8 in the same manner as above, except that the incubating process is not performed.
A sample (comparative product) having the wiring 3 made of an Al—Cu alloy of μm was prepared.

An EM resistance test and an SM resistance test were performed on these samples under the following conditions. The grain diameter of the sample used in this test was about 2.4 μm. (EM resistance test) Environmental temperature 200 ° C. Current density 5 × 10 ⁵ A / cm ² Evaluation method Evaluation was performed by the time taken for 50% of the sample to break. (SM resistance test) Environmental temperature 170 ° C. Current density 5 × 10 ⁵ A / cm ² Evaluation method Evaluation was performed by the time taken for 50% of the sample to break.

The results of the EM resistance test are shown in Table 1, and the results of the SM resistance test are shown in Table 2.

[0020]

[Table 1]

[0021]

[Table 2]

From Table 1, the invention product having a wiring width of 0.8 μm has an EM resistance of about 1 as compared with the comparative product having the same wiring width.
The invention product having a 1.7 times improvement (330 hours) and a wiring width of 1.2 μm has an EM resistance improved by about 7.2 times (172 hours) as compared to a comparative product having the same wiring width, and a wiring width. Is 2.4
The invention product of μm is EM compared to the comparative product having the same wiring width.
Durability is increased by 5 times (80 hours) and wiring width is 4.8 μm
It can be seen that the invented product of No. 2 improved the EM resistance by 4.5 times (70 hours) as compared with the comparative product having the same wiring width. From this, by performing the above-mentioned constant temperature standing treatment, the EM of the semiconductor device is obtained.
It was confirmed that the resistance can be significantly improved.
It was also confirmed that the improvement of the EM resistance is particularly effective for a wiring having a narrow wiring width and a bamboo structure.

Also, from Table 2, the invention product having a wiring width of 0.8 μm has a higher SM resistance than the comparative product having the same wiring width.
Approximately 2.7 times (500 hours) improvement, wiring width 1.2 μm
The invented product has improved SM resistance by about 2.3 times (450 hours) and has a wiring width of 2.4 as compared with the comparative product having the same wiring width.
The invention product of μm is SM compared to the comparative product having the same wiring width.
It was confirmed that the resistance was improved 1.4 times (200 hours). Further, it can be seen that the SM product of the invention product having the wiring width of 4.8 μm is 1.1 times lower than that of the comparative product having the same wiring width. From this, in order to significantly improve the SM resistance of the semiconductor device by performing the above-mentioned incubating treatment, it is particularly required that the wiring width is narrow (about 1.2 μm or less) and the wiring has a bamboo structure. It was confirmed to be done.

In this embodiment, Al = 99.5%,
Although the wiring 3 made of an Al—Cu alloy having a composition of Cu = 0.5% is formed, the composition ratio of each component of the wiring 3 made of an Al—Cu alloy is not limited to this, and may be determined as desired. Good. The wiring 3 made of an Al-Cu alloy may contain Si as long as the concentration is equal to or lower than the solid solution limit with respect to Al at the isothermal treatment temperature.

In addition, although the Al alloy containing Cu was used as the wiring material in this embodiment, the present invention is not limited to this, and an Al alloy containing any of Sc, Pd, and Hf is used instead of Cu. Even if it is, the same effect can be obtained. Further, in this embodiment, the constant temperature standing treatment was performed at 250 ° C. for 10 hours, but the present invention is not limited to this, and the constant temperature standing treatment may be performed at a temperature not higher than the solid solubility limit of Cu.

Further, it is desirable to carry out this isothermal standing treatment, for example, after the completion of the isothermal standing treatment, such as after completion of the assembling step, when heat treatment at a temperature above the solid solubility limit is not performed again. This is due to the constant temperature treatment
This is to prevent the precipitated Al-Cu based alloy from becoming a solid solution again in the Al alloy due to the subsequent heat treatment.

[0027]

As described above, the method for manufacturing a semiconductor device according to the present invention contains a predetermined amount of Cu and Si at a concentration not higher than the solid solution limit with respect to Al at the isothermal treatment temperature, and Wiring made of an Al alloy having a bamboo structure is subjected to an incubating treatment at a temperature below the solid solution limit of Cu to Al, so that Si is not deposited in the wiring and an Al-Cu alloy is effectively deposited. Can be made. This phenomenon exerts a remarkable effect particularly in a fine wiring having a bamboo structure, and the EM resistance and the SM of the wiring are remarkable.
The resistance can be greatly improved.

Then, instead of Cu, Sc, Pd,
The same isothermal treatment is also performed on the wiring made of an Al alloy containing any one of Hf, so that the grain boundaries of the wiring may have Al-Sc alloy, Al-Pd alloy, Al-Hf.
Since the system alloy can be effectively precipitated, the EM resistance and SM resistance of the wiring can be significantly improved.

By performing the above-mentioned incubating treatment at 300 ° C. or lower, in the fine wiring having a bamboo structure, Al-Cu type alloy, Al-Sc type alloy, Al and
The -Pd alloy and the Al-Hf alloy can be effectively precipitated.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a part of a manufacturing process of a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a bamboo structure of wiring of a semiconductor device according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing an Al alloy wiring structure made of normal polycrystalline Al.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor device 2 Oxide film 3 Wiring consisting of Al-Cu alloy 4 Passivation film 5 Grain 6 Wiring

Claims (3)

[Claims] 1. A method for manufacturing a semiconductor device, wherein wiring made of an aluminum alloy containing copper is subjected to an incubating treatment at a temperature not higher than a solid solubility limit of copper in aluminum, wherein a predetermined amount of copper is contained and silicon is kept at the isothermal temperature. A method for manufacturing a semiconductor device, comprising: performing a constant-temperature standing treatment on a wiring made of an aluminum alloy having a bamboo structure and having a concentration not higher than a solid solubility limit at a standing-treatment temperature. 2. A wiring made of an aluminum alloy containing any of scandium, palladium and hafnium, and kept at a temperature below the solid solubility limit of any of scandium, palladium and hafnium contained in the aluminum with respect to aluminum. A method for manufacturing a semiconductor device, wherein a predetermined amount of scandium, palladium, or hafnium is contained, silicon is contained at a concentration not higher than a solid solution limit for aluminum at the incubation temperature, and a bamboo structure is provided. A method of manufacturing a semiconductor device, wherein the wiring made of an aluminum alloy is subjected to the constant temperature treatment. 3. The method for manufacturing a semiconductor device according to claim 1, wherein the incubating process is performed at 300 ° C. or lower.