JPH06310508A - Method of manufacturing semiconductor device - Google Patents

Abstract

PURPOSE:To enhance a step coverage and EM resistance and SM resistance by a method wherein, after an Al alloy is vapor-deposited at a substrate temperature of a specific value or more and the Al alloy is patterned to form a wire, it is left as it is at a constant temperature at a temperature of a solution limit value or less of a metal included in the Al alloy to Al. CONSTITUTION:After an oxide film 2 is formed on a semiconductor substrate 1, a contact hole 4 is opened in a specific location of the oxide film 2. A reflow sputter method of 400 deg.C or more is executed for the semiconductor substrate 1 opening this contact hole 4 and a lower wire 3 composed of an Al-Cu alloy is formed on the entire surface. Thereafter, an interlayer insulation film 5 is formed on the lower layer wire 3 and the oxide film 2. Further, a through hole 6 is opened in the interlayer insulation film 5 and the reflow sputter method of 400 deg.C or more is executed for the substrate 1 to form an upper layer wire 7 which is electrically connected with the lower layer wire 3. Thereafter, a passivation film 8 is formed thereon and left as it is at a constant temperature. Thus, a step coverage of a wire can be enhanced.

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 Conventionally, with the miniaturization and high integration of semiconductor devices, contact holes for electrically connecting to a semiconductor substrate or through holes for electrically connecting to a base metal have been formed. There is a demand for a metal wiring forming technique that reduces the size and sufficiently secures step coverage.

As one of the techniques for forming metal wiring, a metal wiring material is vapor-deposited at a temperature of 400 ° C. or higher, or after the metal wiring material is vapor-deposited, the metal wiring material is heated at a temperature of 500 ° C. or higher. A reflow sputtering method has been proposed in which the metal wiring material is caused to flow into a contact hole or a through hole. Further, with the miniaturization and high integration of semiconductor devices, the miniaturization of elements progresses, the current density of wiring increases, local disconnection and resistance increase easily occur, and EM resistance and SM resistance are increased. The problem of lowering occurs. This electromigration is a phenomenon in which electrons collide with metal ions to generate voids, which leads to disconnection. Stress migration is a phenomenon in which the wiring is disconnected due to stress generated in the wiring during the manufacturing process of a semiconductor device. Is.

Therefore, as one of the methods for improving the EM resistance of wiring, for example, as a metal wiring material, aluminum (hereinafter referred to as "Al") and a desired amount of copper (hereinafter referred to as "C") are used.
u ”) added Al alloy (hereinafter referred to as“ Al—Cu
The method of using "alloy" is introduced. The wiring made of this Al-Cu alloy is subjected to a desired heat treatment to precipitate an Al-Cu-based alloy at the grain boundaries of the wiring film and the like, and this is used as a sink for voids.
M resistance is improved (for example, Japanese Patent Application No. 4-34938).
No. 2).

[0005]

However, the wiring formed by the reflow sputtering method is vapor-deposited at a temperature of 400 ° C. or higher, or is heat-treated at 500 ° C. or higher. There is a problem that it becomes a solid solution in the wiring metal and it is difficult to sufficiently deposit the Al—Cu based alloy on the grain boundaries of the wiring.

Further, according to the reflow sputtering method, A
l When a single metal wiring is formed, there is a problem that crystal defects are likely to exist in the wiring. An object of the present invention is to solve such a conventional problem, and to provide a method for manufacturing a semiconductor device having a wiring with improved step coverage and improved EM resistance and SM resistance. The purpose is to

[0007]

In order to achieve this object, according to the present invention, an Al alloy is vapor-deposited at a substrate temperature of 400 ° C. or higher, and the Al alloy is patterned to form a wiring. The present invention provides a method for manufacturing a semiconductor device, which is characterized in that the metal contained in (1) is kept at a temperature not higher than the solid solubility limit for Al.

Then, an alloy containing a predetermined amount of Cu and silicon (hereinafter referred to as "Si") having a Cu content or less is vapor-deposited at a substrate temperature of 400 ° C. or more, and the alloy is patterned to form wiring. After the formation of Cu, a method for manufacturing a semiconductor device is provided, which is characterized by incubating the Cu at a temperature not higher than a solid solution limit of the alloy. In addition, an alloy containing a predetermined amount of Cu, which contains a metal other than Cu at a concentration not higher than the solid solubility limit of the metal with respect to the alloy at a constant temperature treatment temperature to be performed later is 400 ° C.
A method for manufacturing a semiconductor device, comprising vapor-depositing at the above substrate temperature, patterning the alloy to form a wiring, and then incubating the Cu at a temperature not higher than a solid solution limit of the alloy. Is.

[0009] Also, the deposited Al alloy contains 500
The present invention provides a method for manufacturing a semiconductor device, which comprises performing a heat treatment at a temperature of not less than ° C and then allowing the metal contained in the Al alloy to be kept at a temperature not higher than a solid solution limit for Al. Then, after depositing an alloy containing a predetermined amount of Cu and Si of the Cu content or less and subjecting the alloy to a heat treatment at a temperature of 500 ° C. or higher, the Cu is less than the solid solubility limit of the alloy. The present invention provides a method for manufacturing a semiconductor device, which is characterized by incubating at a constant temperature.

Furthermore, an alloy containing a predetermined amount of Cu, which contains a metal other than Cu at a concentration not higher than the solid solution limit of the metal with respect to the alloy at the temperature of the subsequent incubating treatment, is vapor-deposited. The present invention provides a method for manufacturing a semiconductor device, which comprises subjecting the alloy to a heat treatment at a temperature of 500 ° C. or higher, and then keeping the Cu at a temperature not higher than the solid solution limit of the alloy.

Further, the present invention provides a method for manufacturing a semiconductor device, which is characterized in that the isothermal standing is performed at a temperature of 300 ° C. or lower.

[0012]

According to the present invention, an Al alloy is vapor-deposited at a substrate temperature of 400 ° C. or higher, and the Al alloy is patterned to form wiring.
Since it is kept at a temperature not higher than the solid solubility limit for l, the wiring having improved step coverage, EM resistance and SM resistance can be formed.

That is, first, by depositing an Al alloy at a substrate temperature of 400 ° C. or higher, the Al alloy is caused to flow into the contact holes or through holes, and the step coverage of wiring is improved. Then, by incubating at a temperature not higher than the solid solution limit of the metal contained in the Al alloy with respect to Al, by vapor deposition at the temperature of 400 ° C. or higher, the crystal defects generated in the wiring are recovered, The Al alloy dissolved in the wiring can be sufficiently deposited at the grain boundaries of the wiring. Therefore, the step coverage, EM resistance, and SM resistance of the wiring can be improved.

Then, an alloy containing a predetermined amount of Cu and Si of the Cu content or less is vapor-deposited at a substrate temperature of 400 ° C. or higher, and the alloy is patterned to form wiring. By incubating at a temperature not higher than the solid solubility limit for the alloy, the alloy containing Cu can be sufficiently precipitated at the grain boundaries of the wiring. Further, since the content of Si is smaller than the content of Cu, it is possible to prevent Si from being deposited in the wiring and narrowing the substantial wiring width of the wiring, resulting in EM resistance. Does not decrease. Therefore, wiring step coverage, EM
Resistance and SM resistance can be improved.

Further, an alloy containing a predetermined amount of Cu and containing a metal other than Cu at a concentration not higher than the solid solubility limit of the metal with respect to the alloy at a temperature of the subsequent incubating treatment is 400 ° C. or higher. After vapor deposition at a substrate temperature and patterning of the alloy to form wiring, the alloy containing Cu in the grain boundaries of the wiring is kept at a temperature not higher than the solid solubility limit of Cu with respect to the alloy. It can be sufficiently deposited. Therefore, wiring step coverage, EM
Resistance and SM resistance can be improved.

[0016] Also, the deposited Al alloy contains 500
After performing the heat treatment at a temperature of ℃ or more, by allowing the metal contained in the Al alloy to be kept at a temperature not higher than the solid solubility limit for Al, step coverage, EM resistance and S
Wiring with improved M resistance can be formed. That is,
First, the vapor-deposited Al alloy is heat-treated at a temperature of 500 ° C. or higher to cause the Al alloy to flow into the contact holes and the through holes to improve the step coverage of the wiring. Thereafter, by keeping the metal contained in the Al alloy at a temperature not higher than the solid solubility limit of Al in Al, the crystal defects generated in the wiring are recovered by the high temperature (500 ° C. or higher) heat treatment, or The Al alloy that has been solid-solved therein can be sufficiently precipitated at the grain boundaries of the wiring. Therefore, the step coverage, EM resistance, and SM resistance of the wiring can be improved.

Further, an alloy containing a predetermined amount of Cu and Si whose content is equal to or lower than the Cu content is vapor-deposited, and the alloy is deposited with 500
After the heat treatment is performed at a temperature of ℃ or more, the Cu-containing alloy can be sufficiently precipitated in the grain boundaries of the wiring by incubating the Cu at a temperature not higher than the solid solubility limit of the alloy. . Further, since the content of Si is smaller than the content of Cu, it is possible to prevent Si from being deposited in the wiring and narrowing the substantial wiring width of the wiring, resulting in EM resistance. Does not decrease. Therefore, the step coverage, EM resistance, and SM resistance of the wiring can be improved.

Furthermore, an alloy containing a predetermined amount of Cu, which contains a metal other than Cu at a concentration not higher than the solid solubility limit of the metal with respect to the alloy at the temperature of the subsequent incubating, is vapor-deposited. After heat-treating the alloy at a temperature of 500 ° C. or higher, the Cu is allowed to stand at a temperature not higher than the solid solubility limit of the Cu with respect to the alloy so that C
The alloy containing u can be sufficiently precipitated. Therefore, the step coverage, EM resistance, and SM resistance of the wiring can be improved.

Further, by performing the above-mentioned constant temperature incubation at a temperature of 300 ° C. or lower, in addition to the above-mentioned action, an Al alloy (Al—Cu etc.) can be more efficiently deposited on the grain boundaries of the wiring. Further, it is desirable that the isothermal treatment is performed, for example, after completion of the assembling step, and after the isothermal treatment is completed, when the heat treatment at a temperature higher than the solid solubility limit is not performed again. This is to prevent the Al alloy (Al—Cu or the like) precipitated by the above-mentioned constant temperature treatment from becoming a solid solution again in the wiring due to the subsequent heat treatment.

[0020]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a partial cross-sectional view showing a part of the manufacturing process of a semiconductor device according to an embodiment of the invention. Figure 1
In the step shown in (1), after the oxide film 2 is formed on the semiconductor substrate 1 which has been subjected to a desired treatment, a contact hole 4 is opened at a predetermined position of the oxide film 2 and the semiconductor substrate 1 at this portion is opened. Exposed.

Next, the semiconductor substrate 1 having the contact holes 4 opened is subjected to a reflow sputtering method in which the temperature is raised to about 500 ° C., and Al = 99.5%, Cu = 0.
A wiring film made of an Al-Cu alloy having a composition of 5%
Deposition is performed with a film thickness of about 0.8 μm. Thus, by depositing the wiring film by the reflow sputtering method, the Al
Since the Cu alloy can sufficiently flow into the contact hole 4, the step coverage of the wiring film can be improved.

Next, the wiring film is patterned to form a lower layer wiring 3A electrically connected to the semiconductor substrate 1 and a lower layer wiring 3B electrically connected to an upper layer wiring formed later through the contact hole 4. To do. afterwards,
An interlayer insulating film 5 is formed on the lower wirings 3A and 3B and the oxide film 2.

Next, in the step shown in FIG.
A through hole 6 for electrically connecting with the lower layer wiring 3B is opened in the interlayer insulating film 5 obtained in the step (1), and the lower layer wiring 3B in this portion is exposed. Then, the semiconductor substrate 1 having the through holes 6 is opened at 500 ° C.
Perform reflow sputtering with moderate heating, and
Al-with a composition of l = 99.5%, Cu = 0.5%
A wiring film made of a Cu alloy is vapor-deposited with a film thickness of about 0.8 μm. As described above, by vapor-depositing the wiring film by the reflow sputtering method, the Al—Cu alloy can be made to sufficiently flow into the through hole 6, so that the step coverage of the wiring film can be improved.

Next, this wiring film is patterned to form the upper layer wiring 7 electrically connected to the lower layer wiring 3B through the through hole 6. Then, a passivation film 8 is formed on the upper wiring 7 and the interlayer insulating film 5. After that, the semiconductor substrate 1 on which the passivation film 8 is formed is left at a constant temperature of 250 ° C. for 10 hours. By this constant temperature standing, the Al—Cu based alloy can be sufficiently deposited on the grain boundaries of the lower layer wirings 3A and 3B and the upper layer wiring 7.

In this embodiment, the wiring material is A
Al-with a composition of l = 99.5%, Cu = 0.5%
Although the Cu alloy is used, the composition ratio of each component of the Al-Cu alloy is not limited to this, and may be determined as desired. Also,
Although the Al—Cu alloy is used as the wiring material in the present embodiment, the present invention is not limited to this, and other Al alloys such as an Al—Sc alloy, an Al—Pd alloy, and an Al—Hf alloy may be used. In this case, the temperature of the metal contained in the Al alloy may be kept at a temperature not higher than the solid solubility limit for Al.

Further, as the wiring material, an alloy containing a predetermined amount of Cu and Si whose content is equal to or less than the Cu content may be used, and an alloy containing a predetermined amount of Cu may be used. An alloy containing a metal other than Cu at a concentration not higher than the solid solution limit of the metal with respect to the alloy at the isothermal treatment temperature to be performed later may be used. In this case, the Cu may be allowed to stand at a temperature not higher than the solid solution limit of the alloy.

Then, in this embodiment, the semiconductor substrate 1 is made of 5
The wiring film is vapor-deposited by the reflow sputtering method heated at 00 ° C., but the heating temperature of the semiconductor substrate 1 is not limited to this.
It may be 400 ° C. or higher. Further, after the wiring film is deposited, heat treatment may be performed at a temperature of 500 ° C. or higher. Next, as the wiring material, Al alone, Al = 95.5%, C
Al-Cu alloy with composition of u = 0.5%, Al = 9
Al-C with composition of 7%, Cu = 2%, Si = 1%
A sample in which wiring is formed in the same manner as in this embodiment using a u-Si alloy, and wiring is formed in the same manner as in this embodiment using the same wiring material, and then the incubating is not performed. Samples were manufactured and the EM resistance of both was evaluated under the conditions shown below. (EM resistance test) Environmental temperature 200 ° C. Current density 5 × 10 ⁵ A / cm ² Evaluation method Time until 50% of the sample that was not incubated for a period of time was broken / 50 of the sample that was incubated for a period of time
Time until disconnection of% This result is shown in Table 1.

Next, using a wiring material similar to that described above, a wiring was formed by a sputtering method at a substrate temperature of 200 ° C., and then the sample was subjected to the same incubation as in the present embodiment,
After the wiring was formed by the usual sputtering method using the same wiring material as the above and the substrate temperature was 200 ° C., a sample without the above-mentioned constant temperature incubation was manufactured, and the EM resistance of both was set under the same conditions as above. evaluated. The results are shown in Table 1.

[0029]

[Table 1]

From Table 1, it can be seen that the sample formed by the reflow sputtering method is significantly improved in EM resistance by being left at a constant temperature as compared with the sample formed by the normal sputtering method. This is because the reflow sputtering method deposits a wiring film at a high temperature, so that the number of crystal defects is larger than that of a wiring film deposited by a normal sputtering method and the precipitation of Al-Cu alloy is less. This is because. That is, the effect of recovering the crystal defects and the effect of precipitating the Al—Cu based alloy by the above-mentioned standing at a constant temperature were remarkably exhibited.

Next, using the same wiring material as described above, wiring was vapor-deposited by a normal sputtering method at a substrate temperature of 200 ° C., heat treated at 500 ° C., and then kept at 250 ° C. for 10 hours. After the heat treatment at 500 ° C. and the sample, the sample without the incubating was manufactured, and the EM resistance of both was evaluated under the same conditions as described above. The results are shown in Table 2.

Next, after using the same wiring material as described above and depositing the wiring by the usual sputtering method with the substrate temperature of 200 ° C., the heat treatment at 500 ° C. is not performed and the temperature is set to 1 ° C. at 250 ° C.
Samples that have been allowed to incubate for 0 hours and the substrate temperature at 200 ° C
After depositing the wiring by the normal sputtering method,
Manufacture samples without heat treatment at ℃ and constant temperature,
Both EM resistances were evaluated under the same conditions as above. The results are shown in Table 2.

[0033]

[Table 2]

It can be seen from Table 2 that the sample which has been heat-treated at 500 ° C. has a remarkable improvement in EM resistance by being left at a constant temperature as compared with the sample which has not been heat-treated. From the above, it was proved that the wiring formed by the method for manufacturing a semiconductor device according to the present invention has improved step coverage and EM resistance.

[0035]

As described above, in the method of manufacturing a semiconductor device according to the present invention, an Al alloy is vapor-deposited at a substrate temperature of 400 ° C. or higher, the Al alloy is patterned to form a wiring, and then the Al is formed. Since the metal contained in the alloy is left to incubate at a temperature below the solid solubility limit for Al, the Al alloy is vapor-deposited at a substrate temperature of 400 ° C. or higher to cause the Al alloy to flow into the contact holes and through holes. As a result, the step coverage of the wiring can be improved, the crystal defects generated in the wiring can be recovered, and the Al alloy dissolved in the wiring can be sufficiently precipitated at the grain boundaries of the wiring. it can. As a result, it is possible to improve the step coverage of wiring, the EM resistance, and the SM resistance.

The same effect as described above can be obtained when an alloy containing a predetermined amount of Cu and Si having a Cu content less than that is used. Also, when an alloy containing a predetermined amount of Cu and containing a metal other than Cu at a concentration not higher than the solid solubility limit of the metal with respect to the alloy at the isothermal treatment temperature to be performed later is used, The same effect can be obtained.

Further, the deposited Al alloy is coated with 500
After heat treatment at a temperature of ℃ or more, by allowing the metal contained in the Al alloy to be kept at a temperature not higher than the solid solubility limit for Al, the Al alloy is allowed to flow into the contact holes and through holes. The step coverage of the wiring can be improved, the crystal defects generated in the wiring can be recovered, and the Al alloy dissolved in the wiring can be sufficiently precipitated at the grain boundaries of the wiring. . As a result, wiring step coverage, EM resistance and SM
Resistance can be improved.

The same effect as described above can be obtained when an alloy containing a predetermined amount of Cu and Si having a Cu content not more than the above is used. Furthermore, a certain amount of C
The same effect as described above is obtained when an alloy containing u, which contains a metal other than Cu at a concentration not higher than the solid solubility limit of the metal with respect to the alloy at the temperature of the subsequent incubation treatment is used. be able to.

Further, by performing the above-mentioned constant temperature incubation at a temperature of 300 ° C. or lower, in addition to the above effects, Al alloy (Al—Cu etc.) can be more efficiently deposited at the grain boundaries of the wiring.

[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.

[Explanation of symbols]

 1 Semiconductor Device 2 Oxide Film 3 Lower Layer Wiring 4 Contact Hole 5 Interlayer Insulation Film 6 Through Hole 7 Upper Layer Wiring 8 Passivation Film

Claims (7)

[Claims] 1. An aluminum alloy is vapor-deposited at a substrate temperature of 400 ° C. or higher, the aluminum alloy is patterned to form wiring, and the temperature of the metal contained in the aluminum alloy is lower than the solid solubility limit for aluminum. A method of manufacturing a semiconductor device, which is characterized by allowing to stand at a constant temperature. 2. An alloy containing a predetermined amount of copper and silicon having a content not higher than the copper content is vapor-deposited at a substrate temperature of 400 ° C. or higher, and the alloy is patterned to form wiring. A method for manufacturing a semiconductor device, which is characterized by incubating at a temperature equal to or lower than a solid solubility limit for the alloy. 3. An alloy containing a predetermined amount of copper, the alloy containing a metal other than copper at a concentration not higher than the solid solubility limit of the metal with respect to the alloy at a temperature of a subsequent incubating treatment.
A method for manufacturing a semiconductor device, comprising vapor-depositing at a substrate temperature of 00 ° C. or higher, patterning the alloy to form wiring, and then keeping the copper at a temperature not higher than a solid solution limit of the alloy. 4. The vapor-deposited aluminum alloy has a temperature of 500 ° C.
After the heat treatment is performed at the above temperature, the method for manufacturing a semiconductor device is characterized in that the metal contained in the aluminum alloy is allowed to stand at a temperature not higher than a solid solution limit for aluminum. 5. An alloy containing a predetermined amount of copper and silicon having a content of copper or less is vapor-deposited, the alloy is heat-treated at a temperature of 500 ° C. or more, and then the copper is solidified with respect to the alloy. A method for manufacturing a semiconductor device, which is characterized by incubating at a temperature below the melting limit. 6. An alloy containing a predetermined amount of copper, which comprises depositing a metal other than copper at a concentration not higher than the solid solubility limit of the metal with respect to the alloy at a temperature of the subsequent incubation treatment, A method for manufacturing a semiconductor device, which comprises subjecting an alloy to a heat treatment at a temperature of 500 ° C. or higher and then keeping the copper at a temperature not higher than a solid solution limit of the alloy. 7. The method of manufacturing a semiconductor device according to claim 1, wherein the isothermal standing is performed at a temperature of 300 ° C. or lower.