JP2000277456A - Semiconductor device and manufacture of it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high copper-diffusion-barrier characteristics as well as high conductivity by comprising a wiring of copper or copper alloy and a copper-diffusion preventive film which prevents diffusion of copper from the wiring, and allowing the copper-diffusion preventive film to comprise a rhenium oxide thin-film. SOLUTION: On a p-type silicon substrate 2 comprising an n+-type diffusion layer 1 on its surface, an inter-layer insulating film 3, for example, of a silicon oxide is formed. A contact hole 4 is opened at a part of the inter-layer insulating film 3 which corresponds to the diffusion layer 1. A copper-diffusion preventive film 5 comprising a rhenium oxide thin-film is formed from the inside surface to the bottom part of the contact hole 4. A wiring 6 of Cu or Cu alloy is embedded in the contact hole 4 where the copper-diffusion preventive film 5 is formed. The rhenium oxide is preferred to be represented with ReOx(x=0.15-0.3).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having an improved copper diffusion preventing film for preventing copper diffusion from a wiring made of copper or a copper alloy, and a method of manufacturing the same.

[0002]

2. Description of the Related Art As a wiring material of a semiconductor device, aluminum (Al) or aluminum alloy (Al alloy) is used.
Is used. However, the wiring made of Al or Al alloy has a problem that it breaks due to electromigration.

For these reasons, copper (Cu) or copper alloy (Cu alloy) having lower resistance and excellent electromigration resistance has attracted attention as a wiring material for next-generation semiconductor devices. A problem in realizing the wiring of Cu or Cu alloy is element deterioration due to Cu diffusion into a silicon substrate or a silicon oxide film which is an insulating film. Conventionally, WN has been used as a copper diffusion prevention film.
_x , WSiN _x and TaN are known.

[0004]

The copper diffusion preventing film is required to have high conductivity in addition to the copper diffusion preventing property (copper barrier property). For example, when an interlayer insulating film made of a silicon oxide film is deposited on a semiconductor substrate, a contact hole is opened in the interlayer insulating film, and copper wiring is buried in the contact hole to achieve conduction with the substrate, thereby preventing diffusion. It is necessary to form a film not only on the side of the contact hole but also on the bottom. In the semiconductor device having such a structure, when the copper diffusion prevention film is made of a high resistance material, the copper diffusion prevention film portion located at the bottom of the contact hole is formed in order to achieve a good connection between the copper wiring and the silicon substrate. The thickness must be increased. An increase in the thickness of the copper diffusion preventing film portion located at the bottom of the contact hole also leads to an increase in the thickness of the side portion at the same time, which effectively reduces the cross-sectional area of the Cu wiring. As a result, the effect of reducing the wiring resistance using Cu as the wiring material is lost.

The above-mentioned conventional copper diffusion preventing material WN
_{Since x} , WSiN _x , and TaN have a resistivity of 200 μΩcm or more, none of them has a sufficiently low resistance. In particular, if the wiring width is further reduced in the future, the cross-sectional area of the Cu wiring will be reduced, so that a copper diffusion prevention film having lower resistance is required.

An object of the present invention is to provide a semiconductor device having a copper diffusion barrier film having high copper diffusion barrier properties and high conductivity, and a method of manufacturing the same.

[0007]

SUMMARY OF THE INVENTION The present inventors have determined that rhenium oxide has excellent copper diffusion barrier properties,
Paying attention to having a low resistivity of a metal level of μΩcm, the present inventors invented a semiconductor device utilizing the low resistance of the wiring made of Cu or Cu alloy by using this rhenium oxide as a copper diffusion preventing film.

That is, a semiconductor device according to the present invention includes a wiring made of copper or a copper alloy and a copper diffusion preventing film for preventing copper diffusion from the wiring. It is characterized by comprising an oxide thin film.

A method for manufacturing a semiconductor device according to the present invention comprises:
Forming an insulating film on a substrate having a diffusion layer; forming a contact hole in the insulating film portion corresponding to the diffusion layer; and forming a copper film made of a rhenium oxide thin film on the inner side surface and the bottom of the contact hole. Forming a diffusion preventing film; and forming a copper or copper alloy wiring in the contact hole having the copper diffusion preventing film.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a semiconductor device according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing one embodiment of the semiconductor device of the present invention. For example, an interlayer insulating film 3 made of, for example, silicon oxide is formed on a p-type silicon substrate 2 having an n ⁺ -type diffusion layer 1 on the surface. Contact hole 4
Is opened in a portion of the interlayer insulating film 3 corresponding to the diffusion layer 1. The copper diffusion preventing film 5 made of a rhenium oxide thin film is formed from the inner surface to the bottom of the contact hole 4. The wiring 6 made of Cu or Cu alloy is buried in the contact hole 4 where the copper diffusion preventing film 5 is formed.

The rhenium oxide is ReO _x (x =
0.15 to 0.3).

It is preferable that the copper diffusion preventing film has a thickness of 10 to 100 nm.

As the Cu alloy, for example, Cu—Si
An alloy, a Cu—Si—Al alloy, or the like can be used.

Next, a method of manufacturing a semiconductor device according to the present invention will be described.

First, after an insulating film made of, for example, silicon oxide is formed on a substrate having a diffusion layer, a contact hole is formed in the insulating film portion corresponding to the diffusion layer.
Subsequently, a rhenium oxide thin film and a copper thin film or a copper alloy thin film are formed on the insulating film including the contact holes. Then, the copper thin film or the copper alloy thin film and the rhenium oxide thin film are etched back by, for example, a chemical mechanical polishing (CMP) technique to thereby form a copper diffusion preventing film made of a rhenium oxide thin film on the inner side surface and the bottom of the contact hole. And a wiring of copper or a copper alloy is formed in the contact hole having the copper diffusion preventing film to manufacture the semiconductor device shown in FIG.

The rhenium oxide thin film and, for example, a copper thin film as a wiring material are, for example, DC shown in FIG.
The film can be formed using a magnetron sputtering apparatus.

At the bottom of the vacuum chamber 11 in FIG. 2, a first and second target holders 14, holding a rhenium oxide target 12 and a Cu target 13, respectively, are provided.
15 are arranged. First and second shutters 16 and 1
Reference numeral 7 is disposed above and close to each of the targets 12 and 13. First and second magnets 18 and 19 rotated by a drive mechanism (not shown) are arranged below and close to the target holders 14 and 15, respectively. First and second DC power supplies 20 and 21 are connected to the target holders 14 and 15, respectively. The substrate holder 23 rotated by the rotation mechanism 22 is disposed near the upper part in the vacuum vessel 11 so as to face the targets 12 and 13. The gas supply pipe 24 is connected to a side wall of the vacuum vessel 11. The exhaust pipe 25 is connected to a side wall of the vacuum vessel 11 facing the gas supply pipe 24.

Next, a method for forming a rhenium oxide thin film and a Cu thin film by the aforementioned DC magnetron sputtering apparatus will be described.

First, a silicon substrate 26 having an interlayer insulating film in which the above-mentioned contact hole is opened is held in a substrate holder 23 such that the front side faces the targets 12 and 13. A mixed gas of oxygen and argon (or argon gas) is supplied into the vacuum vessel 11 through a gas supply pipe 24, and the vacuum vessel 11 is exhausted by an exhaust device (not shown).
The inside gas is exhausted through the exhaust pipe 25 to make the inside of the vacuum vessel 11 a predetermined degree of vacuum. While applying a predetermined DC voltage from the first DC power supply 20 to the target holder 14,
By rotating the magnetron 18 at a predetermined speed,
Rhenium oxide is sputtered from the rhenium oxide target 12 held by the holder 14. The first shutter 16 arranged above the target 14 is opened in a state where the sputtering state is stable, and the substrate holder 23 is rotated at a predetermined speed by a rotating mechanism 22 to thereby form an interlayer insulating film including a contact hole of the substrate 25. A rhenium oxide thin film is formed thereon.

After forming a rhenium oxide thin film having a desired thickness, a mixed gas of oxygen and argon is supplied.
The application of the DC voltage from the first DC power supply 20 to the target holder 14, the rotation of the first magnetron 18 are stopped, and the first shutter 16 is closed.

Next, an argon gas is supplied into the vacuum vessel 11 through a gas supply pipe 24, and the gas in the vacuum vessel 11 is exhausted through an exhaust pipe 25 by an exhaust device (not shown) so that the inside of the vacuum vessel 11 has a predetermined degree of vacuum. To Second
By applying a predetermined DC voltage from the DC power supply 21 to the second target holder 15 and rotating the second magnetron 19 at a predetermined speed, Cu is sputtered from the Cu target 13 held by the second target holder 15. I do. When the sputtering state is stable, the Cu
The second shutter 17 disposed above the target 13 is opened, and the substrate holder 23 is rotated at a predetermined speed by the rotation mechanism 22 to form a Cu thin film on the rhenium oxide thin film on the substrate.

According to the DC magnetron sputtering apparatus of the multi-target type shown in FIG. 2, a two-layer thin film of rhenium oxide / Cu can be formed without breaking the vacuum. It is possible to improve the electrical conductivity at the interface between the copper diffusion prevention film and the Cu wiring.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail.

(Example 1) Using the DC magnetron sputtering apparatus shown in FIG. 2 described above, on a silicon substrate and a silicon substrate having a silicon oxide film on its surface, it is represented by ReO _0.15 , ReO _0.25 and ReO _0.3 under the following conditions. A rhenium oxide thin film having a thickness of 70 nm was formed.

[0026] (the film formation conditions of ReO _x) amount of oxygen introduced; 0sccm, 2.5sccm, 5scc
m, sputter discharge voltage: 575 V, sputter discharge current: 1 A, sputter pressure: 0.6 Pa, substrate temperature: room temperature, distance between substrate and rhenium target: 180 mm.

The resistivity of the rhenium oxide thin film formed on the silicon substrate and the silicon substrate having a silicon oxide film on the surface was measured. The result is shown in FIG. In FIG. 3, a is a resistance characteristic line of a rhenium oxide thin film on a silicon substrate, and b is a resistance characteristic line of a rhenium oxide thin film on a silicon oxide film.

As apparent from FIG. 3, on a silicon substrate,
It can be seen that the rhenium oxide thin film formed on the silicon oxide film has the minimum resistivity when the composition of ReO is _0.15 , and exhibits a low resistivity of about 150 μΩcm.

(Embodiment 2) As shown in FIG. 4, a rhenium oxide thin film having a thickness of 70 nm represented by ReO _0.15 is formed on a silicon substrate 31 by the same method as in Embodiment 1 by using the DC magnetron sputtering apparatus described above. 32, and a thickness of 130 n is formed on the thin film 32 under the following conditions.
A first sample was prepared by forming a Cu thin film 33 of m.

Further, as shown in FIG.
DC magnetron on the silicon oxide film 34
Using a putter device, R
eO _0.1570nm thick rhenium oxide thin film represented by
A film 32 is formed, and a thickness is formed on the thin film 32 under the following conditions.
A second sample is prepared by forming a Cu thin film 33 having a thickness of 130 nm.
did.

(Cu film formation conditions) Introduced gas: argon, sputter discharge voltage: 400 V, sputter discharge current: 1.3 A, sputter pressure: 0.6 Pa, substrate temperature: room temperature, distance between substrate and Cu target: 180 mm .

After holding the first sample shown in FIG. 4 at 500 ° C. and 600 ° C. for 30 minutes in a vacuum of 1 × 10 ⁻³ Pa, the Cu concentration in the Si substrate was measured by secondary ion mass spectrometry (SI
MS). FIG. 6 shows the result.

Further, 1 × second sample shown in FIG. 5 10 ^-3 P
After holding at 500 ° C. and 600 ° C. for 30 minutes in the vacuum of a, the Cu concentration in the silicon oxide film (SiO ₂ film) was measured by secondary ion mass spectrometry (SIMS). FIG. 7 shows the result.

Further, the first and second shown in FIG. 4 and FIG.
Sample was placed in a vacuum of 1 × 10 ⁻³ Pa at room temperature, 400 ° C., and 4
After holding at 50 ° C., 500 ° C. and 600 ° C. for 30 minutes, the resistivity of the Cu thin film was measured. FIG. 8 shows the result. Note that a in FIG. 8 is a resistance characteristic line of the Cu thin film of the first sample, and b is a resistance characteristic line of the Cu thin film of the second sample.

6 and 7, when vacuum annealing was performed at 500 ° C., no diffusion of Cu into Si and SiO ₂ was observed. It can be seen that the diffusion of

As is apparent from FIG. 8, the Cu thin film shows the same change in resistivity regardless of whether it is formed on a silicon substrate or a rhenium oxide thin film of a silicon oxide film. It can be seen that the resistance of the Cu thin film formed on the rhenium oxide thin film increases.

From the above results, it is considered that the Cu diffusion preventing temperature of the rhenium oxide thin film having the composition of ReO _0.15 is about 500 ° C. However, considering that the maximum heating temperature in the current semiconductor device manufacturing process is about 400 to 450 ° C., the rhenium oxide thin film having the composition of ReO _0.15 is sufficient under the temperature in the semiconductor device manufacturing process. It can be seen that it has excellent copper diffusion prevention performance.

[0038]

As described above in detail, according to the present invention, a copper diffusion barrier film having a high copper diffusion barrier property and a high conductivity is provided, and the wiring made of Cu or Cu alloy has a low resistance. It is possible to provide a highly reliable semiconductor device capable of high-speed operation utilizing the above and a method of manufacturing the same.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a semiconductor device according to the present invention.

FIG. 2 is a schematic diagram showing a DC magnetron sputtering apparatus used for forming a copper diffusion preventing film and a Cu thin film constituting the semiconductor device of the present invention.

FIG. 3 is a characteristic diagram showing the resistivity of a rhenium oxide thin film represented by ReO _0.15 , ReO _0.25 , and ReO _{0.3 formed} on a silicon substrate and a silicon oxide film, respectively.

FIG. 4 is a cross-sectional view showing a first sample in which a rhenium oxide thin film and a Cu thin film are formed on the silicon substrate used in Example 2.

FIG. 5 is a cross-sectional view showing a second sample in which a rhenium oxide thin film and a Cu thin film are formed on a silicon oxide film of a silicon substrate used in Example 2.

FIG. 6 shows the S after annealing at a predetermined temperature in a vacuum.
The figure which shows the Cu density | concentration in i.

FIG. 7 shows the S after annealing at a predetermined temperature in a vacuum.
It shows the concentration of Cu iO _2.

FIG. 8 is a characteristic diagram showing a relationship between the temperature and the resistivity of the Cu thin film after the first and second samples are held in a vacuum atmosphere.

[Explanation of symbols]

 2, 31: silicon substrate, 3: interlayer insulating film, 4: contact hole, 5: copper diffusion preventing film made of rhenium oxide, 6: wiring of Cu or Cu alloy, 32: rhenium oxide thin film, 33: Cu thin film 34 ... a silicon oxide film.

Continued on the front page F-term (reference) 4M104 AA01 BB36 CC01 DD37 DD40 DD42 FF18 HH04 HH16 5F033 HH11 HH35 JJ11 JJ35 KK01 MM05 NN06 NN07 PP15 PP16 XX10 XX28

Claims (2)

[Claims] 1. A semiconductor device having a wiring made of copper or a copper alloy and a copper diffusion preventing film for preventing copper diffusion from the wiring, wherein the copper diffusion preventing film is made of a rhenium oxide thin film. Characteristic semiconductor device. A step of forming an insulating film on a substrate having a diffusion layer; a step of forming a contact hole in a portion of the insulating film corresponding to the diffusion layer; and a step of forming rhenium oxide on an inner surface and a bottom of the contact hole. A method of forming a copper diffusion prevention film made of an object thin film; and a step of forming a copper or copper alloy wiring in the contact hole having the copper diffusion prevention film. .