JP2730623B2 - Semiconductor device and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, to a semiconductor device having a fine contact hole having a high aspect ratio and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, as semiconductor devices (devices) have been miniaturized, the aspect ratio of a contact hole (a value obtained by dividing the depth h of a hole by the width or diameter d of the hole) has increased. In the case of a device according to design rules, when the thickness of the insulating film exceeds 1.5 μm, the aspect ratio becomes 4 to 1, that is, 4 or more. After depositing a barrier metal such as Ti / TiN on a semiconductor substrate having such a high aspect ratio contact hole, Al-Si or an Al-Si-Cu alloy is further formed thereon by sputtering. However, it has become impossible to fill (fill) a fine contact hole with a high aspect ratio.

[0003] For example, Japanese Patent Application Laid-Open No. 4-196421 discloses a high aspect ratio by depositing a Ge thin film as a base film on a barrier metal before sputtering Al-Si or an Al-Si-Cu alloy. A method of filling the fine contact hole has been proposed. This is because the Al-Ge alloy formed by the alloying reaction between Ge and Al in the metal wiring has an eutectic temperature of Al-Si
Alternatively, it is a technique utilizing a feature that it is lower than an Al-Si-Cu alloy and is easily melted, so that it easily flows into a fine contact hole. During film formation when the Al-Si alloy is sputtered on the Ge thin film at a temperature lower than that of the Al-Si alloy, that is, at a substrate temperature higher than room temperature and equal to or lower than the eutectic temperature of the Al-Ge alloy, The -Si alloy takes in Ge to form an Al-Ge-Si alloy. This A
The l-Ge-Si alloy causes surface migration and easily flows into the contact hole.

[0004] For example, Japanese Patent Application Laid-Open No. 4-196420 discloses that a Ge layer or a Si layer containing a high concentration of Ge is inserted between the bottom of a contact hole and an underlying barrier metal to provide a high aspect ratio contact. A method has been proposed in which holes can be buried and the contact resistance is reduced.

[0005]

However, in these conventional devices, there is a problem that the resistance value of the wiring or the electrode varies, and the reliability of the device operation is remarkably reduced.

FIG. 4 shows that the contact hole is made of Al-5%.
The contact resistance value once filled (embedded) with Ge is shown. As is clear from FIG. 4, a variation of 10% or more is observed in the contact resistance value.
Note that polysilicon is used for the barrier metal.

[0007] This variation in the resistance value is caused by the fact that Ge, which has been once alloyed into a semi-molten state, precipitates on the barrier metal during cooling to form nodules.

In order to lower the melting point of the alloy, the Ge content of the alloy must be increased, as shown in FIG. As a result, since the solid solution concentration of Ge is almost 0 at room temperature, the size of Ge nodules is significantly increased.

The presence of such a large Ge nodule in the wiring or the electrode metal causes a variation in the resistance value as the contact hole is miniaturized, which leads to deterioration of the electrical characteristics of the device. .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the prior art. It is an object of the present invention to bury high-aspect-ratio fine holes at a relatively low temperature to achieve high reliability. An object of the present invention is to provide a semiconductor device in which a wiring and an electrode structure are formed and a method for manufacturing the same.

[0011]

According to a first basic aspect of the present invention, at least one hole formed in an insulating film on a semiconductor substrate and at least one semiconductor in the hole are provided. A barrier metal formed on a portion in contact with the substrate, and a first A film formed on the barrier metal;
an l-containing metal film and a metal wiring composed of two layers of a second Al-containing metal film having a lower melting point than the first Al-containing metal film formed subsequently on the first Al-containing metal film. A semiconductor device is provided.

The semiconductor device according to the first basic mode has the following embodiments. That is, the first Al-containing metal film is made of Al alone, an Al-Si alloy film, and Al-Si-
This is one selected from a group including a Cu alloy film.

[0013] The second Al-containing metal film is Al-Ge-
Si alloy film, Al-Ge-Si-Cu alloy film, Al-G
This is one selected from the group including an e-alloy film, an Al-Ge-Cu alloy film, an Al-Sn alloy film, and an Al-Sn-Cu alloy film.

The Al—Si alloy film has a Si concentration of 0.1
２2 atomic%.

The Al—Si—Cu alloy film has a Si concentration of 0.1 to 2 at% and a Cu concentration of 0.1 to 2 at%.

The Al—Ge—Si alloy film has a Ge concentration of 0.5 to 30 atomic% and a Si concentration of 0.1 to 2 atomic%.
It is.

Ge of the Al—Ge—Si—Cu alloy film
The concentration is 0.5 to 30 atomic%, the Si concentration is 0.1 to 2 atomic%, and the Cu concentration is 0.1 to 2 atomic%.

The Ge concentration of the Al—Ge alloy film is 0.5
-30 atomic%.

The Al—Ge—Cu alloy film has a Ge concentration of 0.5 to 30 atomic% and a Cu concentration of 0.1 to 2 atomic%.
It is.

The Sn concentration of the Al—Sn alloy film is 0.1
９８98 atomic%.

The Al—Sn—Cu alloy film has a Sn concentration and a Cu concentration of 0.1 to 98 atomic% and 0.1 to 98 atomic%, respectively.
2 atomic%.

According to a second basic aspect of the present invention, there is provided a method of manufacturing a semiconductor device having at least one hole in an insulating film on a semiconductor substrate. Forming a barrier metal on a semiconductor substrate having an oxide film, forming a first Al-containing metal film on the barrier metal, and subsequently forming the first Al-containing metal film on the first Al-containing metal film; Forming a second Al-containing metal film having a lower melting point than the Al-containing metal film;
Thereafter, in order to fill the hole, the second Al-containing metal film is reflowed into the hole in a semi-molten state at a temperature lower than the eutectic temperature of the second Al-containing metal film. The method for manufacturing a semiconductor device described above is provided.

The method of manufacturing a semiconductor device according to the second basic aspect has the following embodiments. That is, the first Al-containing metal film is one selected from a group including Al alone, an Al-Si alloy film, and an Al-Si-Cu alloy film.

The second Al-containing metal film is made of Al-Ge-
Si alloy film, Al-Ge-Si-Cu alloy film, Al-G
This is one selected from the group including an e-alloy film, an Al-Ge-Cu alloy film, an Al-Sn alloy film, and an Al-Sn-Cu alloy film.

The Al—Si alloy film has a Si concentration of 0.1
２2 atomic%.

The Al—Si—Cu alloy film has a Si concentration of 0.1 to 2 at% and a Cu concentration of 0.1 to 2 at%.

The Al—Ge—Si alloy film has a Ge concentration of 0.5 to 30 atomic% and a Si concentration of 0.1 to 2 atomic%.
It is.

Ge of the Al—Ge—Si—Cu alloy film
The concentration is 0.5 to 30 atomic%, the Si concentration is 0.1 to 2 atomic%, and the Cu concentration is 0.1 to 2 atomic%.

The Ge concentration of the Al—Ge alloy film is 0.5
-30 atomic%.

The Al—Ge—Cu alloy film has a Ge concentration of 0.5 to 30 atomic% and a Cu concentration of 0.1 to 2 atomic%.
It is.

The Al—Sn alloy film has a Sn concentration of 0.1
９８98 atomic%.

The Al—Sn—Cu alloy film has a Sn concentration and a Cu concentration of 0.1 to 98 atomic% and 0.1 to 98 atomic%, respectively.
2 atomic%.

[0033]

As is apparent from the above embodiments, the present inventors realize a semi-molten state after sputtering instead of the conventional method of embedding holes by realizing a semi-molten state on the substrate surface during sputtering. Reflow method (Proceedings of VSI) multilevel interconnection conference
LSI Multilevel In-terconnection Conference), 19
(1991, p. 326) and succeeded in adopting this in the manufacture of semiconductor devices.

In this reflow method, the fact that when the reflow temperature is increased, the surface of the deposited metal thin film starts to melt first from the analysis using experiments and simulations using low-speed electron diffraction. I found it.

That is, if only the melting point of the surface layer of the metal thin film can be lowered by alloying with Ge, holes can be buried at a low temperature, and
The present invention has been completed on the assumption that Ge nodules can be reduced to a negligible extent. In other words, since reflow occurs only on the surface of the deposited film, Ge
The only place where the melting point is lowered by adding is the surface of the film. As a result, by reducing the Ge additive and not allowing Ge to contact the barrier metal, the present invention not only lowers the reflow temperature but also lowers the Ge concentration in the final Al film. I have. This allows
The present invention can remarkably improve the reliability of the electrode and wiring steps in a device having a design rule of 0.25 μm, for example.

[0036]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1A and 1B and FIGS. 2C and 2C.
(D) is sectional drawing which shows one Embodiment of the manufacturing process regarding the semiconductor device of this invention, respectively in order of a process.

An oxide insulating film 3 is formed by a CVD method or the like on a Si substrate 2 on which a p ⁺ diffusion layer 1 which is a part of an element such as a transistor is formed, and the oxide insulating film 3 is etched to have a diameter of 0.1 mm. Contact hole 4 of 25 μm, aspect ratio 4
To form (Refer to FIG. 1 (a).) Next, a Ti thin film 5 is sputter-deposited at room temperature to a thickness of 20 nm.
In this state, a sputter film is formed to a thickness of 100 nm. Thereafter, lamp annealing was performed at 620 ° C. for 30 seconds in a nitrogen atmosphere. (See FIG. 1B.) The Ti / TiN laminated films 5 and 6 function as barrier metals.

Further, as the first Al-containing metal film 7,
AL-Si alloy film containing 1 atomic% of Si, or Si
Containing 1 atomic% of Cu and 0.5 atomic% of Cu, respectively.
A -Si-Cu alloy film was formed on the barrier metals 5 and 6 by sputtering to a thickness of 0.8 µm while the substrate 1 was heated to 20 to 100 ° C. (Refer to FIG. 2 (c).) Subsequently, Ge is 20 atoms on the first Al-containing metal film 7 as the second Al-containing metal film 8 having a lower melting point than the first Al-containing metal film 7. %, Al containing 1 atomic% of Si
-Ge-Si alloy film or Al-Ge-S containing 20 at% Ge, 1 at% Si, and 0.5 at% Cu
An i-Cu alloy film is formed by sputtering to a thickness of 0.01 μm while the substrate 1 is heated to 20 to 100 ° C.
Reflow at 300 ° C. (See FIG. 2D.) As a result, the contact hole 4 is completely filled (buried), and at this time, the variation in the resistance value of the wiring and the electrode falls within 10% as is clear from FIG. It turns out that reliability issues have been resolved.

Here, even if an Al film formed of Al alone was used as the first Al-containing metal film 7, the same effect was obtained.

Further, as the second Al-containing metal film 8, an Al—Ge alloy film containing no Si, an Al—Ge—C
It was found that a similar effect can be obtained by using a u film, an Al—Sn film, or an Al—Sn—Cu film.

Further, it has been found that the object of the present invention is achieved when the Si concentration and the Cu concentration in the first Al-containing metal film 7 are each in the range of 0.1 to 2 atomic%.

The Ge concentration in the second Al-containing metal film 8 is in the range of 0.5% to 30% by atom, and the Si concentration or Sn concentration and the Cu concentration are 0.1 to 2% by atom.
, 0.1 to 98 atomic% of Sn, and 0.1% of Cu.
It has been found that if the content is 1 to 2 atomic%, the object of the present invention can be achieved.

[0044]

As described above, according to the present invention,
It becomes possible to completely fill a fine contact hole having a high aspect ratio, and at this time, it is possible to improve the device characteristics and the reliability of the semiconductor device without causing any deterioration of the electric characteristics.

Further, according to the present invention, since the fine contact holes can be filled by the conventional sputtering method, the conventional manufacturing process can be used as it is, and the manufacturing cost can be reduced. can get.

Furthermore, in the present invention, the wafer as a substrate must be heated to 450 ° C. or higher for the reflow of the second Al-containing metal film. In the present invention, the temperature is much lower than that temperature, for example. Since reflow can be achieved at a substrate heating temperature of 300 ° C., the device characteristics and reliability of the semiconductor device are significantly improved.

The above description is merely illustrative of the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto. Many more modifications and adaptations of the present invention will be readily apparent to those skilled in the art without departing from the scope of the invention.

[Brief description of the drawings]

FIGS. 1A and 1B are cross-sectional views showing one embodiment of a semiconductor device and a method of manufacturing the same according to the present invention in the order of manufacturing steps.

FIGS. 2C to 2D are cross-sectional views showing one embodiment of a semiconductor device and a method of manufacturing the same according to the present invention in the order of manufacturing steps.

FIG. 3 is a graph showing a variation state regarding a contact resistance value of the semiconductor device of the present invention.

FIG. 4 is a graph showing a variation state of a contact resistance value in a conventional example.

FIG. 5 is a graph showing the dependence of the melting point on the Ge concentration in an Al—Ge alloy.

[Explanation of symbols]

Reference ^Signs List 1 p ⁺ diffusion layer 2 Si substrate 3 oxide insulating film 4 contact hole 5, 6 Ti / TiN laminated film (barrier metal) 7 first Al-containing metal film 8 second Al-containing metal film

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H01L 21/90 CD

Claims (22)

(57) [Claims] At least one hole formed in an insulating film on a semiconductor substrate, a barrier metal formed in at least a portion in contact with the semiconductor substrate in the hole, and a first film formed on the barrier metal Al-containing metal film and the first A film subsequently formed on the first Al-containing metal film
a metal wiring comprising two layers of a second Al-containing metal film having a lower melting point than the l-containing metal film. 2. The method according to claim 1, wherein the first Al-containing metal film is one selected from a group including Al alone, an Al—Si alloy film, and an Al—Si—Cu alloy film. Semiconductor device. 3. The method according to claim 2, wherein the second Al-containing metal film is Al-Ge.
-Si alloy film, Al-Ge-Si-Cu alloy film, Al-
2. The semiconductor device according to claim 1, wherein the semiconductor device is one selected from a group including a Ge alloy film, an Al-Ge-Cu alloy film, an Al-Sn alloy film, and an Al-Sn-Cu alloy film. 4. The method according to claim 1, wherein the Al—Si alloy film has a Si concentration of 0.1.
3. The semiconductor device according to claim 2, wherein the content is 1 to 2 atomic%. 5. The Al—Si—Cu alloy film has a Si concentration of 0.1 to 2 atomic% and a Cu concentration of 0.1 to 2 atomic%.
3. The semiconductor device according to claim 2, wherein 6. The semiconductor device according to claim 3, wherein the Al—Ge—Si alloy film has a Ge concentration of 0.5 to 30 at% and a Si concentration of 0.1 to 2 at%. . 7. The G of the Al—Ge—Si—Cu alloy film
4. The semiconductor device according to claim 3, wherein the e concentration is 0.5 to 30 at%, the Si concentration is 0.1 to 2 at%, and the Cu concentration is 0.1 to 2 at%. 8. The Al—Ge alloy film having a Ge concentration of 0.
4. The semiconductor device according to claim 3, wherein the content is 5 to 30 atomic%. 9. The semiconductor device according to claim 3, wherein the Al—Ge—Cu alloy film has a Ge concentration of 0.5 to 30 at% and a Cu concentration of 0.1 to 2 at%. . 10. The semiconductor device according to claim 3, wherein the Sn concentration of the Al—Sn alloy film is 0.1 to 98 atomic%. 11. The Al—Sn—Cu alloy film has a Sn concentration and a Cu concentration of 0.1 to 98 atomic% and 0.1 to 98 atomic%, respectively.
4. The semiconductor device according to claim 3, wherein the content is 1 to 2 atomic%. 12. An insulating film on a semiconductor substrate has at least one
In a method for manufacturing a semiconductor device having two holes, forming a barrier metal on a semiconductor substrate having an oxide film in the holes and on the surface; and forming a first Al-containing metal film on the barrier metal. Followed by the first A
forming a second Al-containing metal film having a lower melting point than the first Al-containing metal film on the l-containing metal film, and then combining the second Al-containing metal film to fill the holes. A method of manufacturing the semiconductor device, comprising: reflowing the second Al-containing metal film in a semi-molten state at a temperature not higher than the crystallization temperature into the hole. 13. The method according to claim 12, wherein the first Al-containing metal film is one selected from a group including Al alone, an Al—Si alloy film, and an Al—Si—Cu alloy film. A method for manufacturing a semiconductor device. 14. The second Al-containing metal film is formed of Al-G
e-Si alloy film, Al-Ge-Si-Cu alloy film, Al
The semiconductor device according to claim 12, wherein the semiconductor device is one selected from a group including a -Ge alloy film, an Al-Ge-Cu alloy film, an Al-Sn alloy film, and an Al-Sn-Cu alloy film. Production method. 15. The method according to claim 13, wherein the Al—Si alloy film has a Si concentration of 0.1 to 2 atomic%. 16. The semiconductor device according to claim 13, wherein the Al—Si—Cu alloy film has a Si concentration of 0.1 to 2 at% and a Cu concentration of 0.1 to 2 at%. Manufacturing method. 17. The semiconductor device according to claim 14, wherein the Al—Ge—Si alloy film has a Ge concentration of 0.5 to 30 at% and a Si concentration of 0.1 to 2 at%. Manufacturing method. 18. The Al—Ge—Si—Cu alloy film has a Ge concentration of 0.5 to 30 at% and a Si concentration of 0.1 to 2%.
The method for manufacturing a semiconductor device according to claim 14, wherein the atomic percentage and the Cu concentration are 0.1 to 2 atomic%. 19. The Al—Ge alloy film having a Ge concentration of 0.5 to 30 atomic%.
The manufacturing method of the semiconductor device described in the above. 20. The semiconductor device according to claim 14, wherein the Al—Ge—Cu alloy film has a Ge concentration of 0.5 to 30 at% and a Cu concentration of 0.1 to 2 at%. Manufacturing method. 21. The Al—Sn alloy film having a Sn concentration of 0.1 to 98 atomic%.
13. The semiconductor device according to claim 1. 22. The Al—Sn—Cu alloy film has a Sn concentration and a Cu concentration of 0.1 to 98 at% and 0.1 to 98 atomic%, respectively.
15. The semiconductor device according to claim 14, wherein the content is 1 to 2 atomic%.