JP2782600B2 - Method for forming copper diffusion preventing film having two-layer structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a copper diffusion barrier film having a two-layer structure. The present invention relates to a method for forming a copper diffusion preventing film having a two-layer structure on a semiconductor substrate and a copper thin film for copper wiring so as to effectively suppress the diffusion.

[0002]

2. Description of the Related Art Generally, as a wiring material of a semiconductor element,
Tungsten having excellent electromigration (hereinafter abbreviated as EM) properties and aluminum having relatively low electric resistance are widely used. However, as the device is reduced to a half submicron geometry, the metal wiring has a reduced EM property, an increased wiring length, an increased resistance due to a reduced metal thin film cross-sectional area, an increased insulation. There is a disadvantage that the operating speed of the device is reduced due to a decrease in the film thickness and a width between metal lines.

In recent years, copper having low electric resistance and excellent EM properties as compared with the aluminum wiring has been proposed as a wiring material. However, copper has low oxidation resistance and fast diffusion (for example, 990 ° C.). In the silicon substrate, the diffusivity (Aldiffusivity) of aluminum is 10 ⁻¹⁴ cm ² /
s , whereas the copper diffusivity is 1
Since it has 0 ^-4 cm ² / s , the movement of electrons in silicon and most metals is accelerated, and as a result, copper is diffused into silicon through the metal film and the element may be disconnected.

[0004] The copper also acts as a recombination center in silicon, reducing the lifetime of minority carriers and affecting the operation of the device. Therefore, in order to use the copper as a wiring material, the above-mentioned disadvantages must be solved. In particular, a large diffusion coefficient in the silicon causes interdiffusion during processing to cause Cu / Si (or Cu / dielectric). Since the thermal stability of the (film) interface is threatened and the reliability of the device is greatly reduced, a diffusion preventing film is required between Cu and Si (or Cu and dielectric film) to prevent such a reaction.

The anti-diffusion film should have no chemical affinity with copper, have no crystal grain boundary defects at high temperatures, and be resistant to high solid solubility and high diffusion of copper and silicon. is there. In the conventional diffusion prevention film, the document `` E. Kolawa.
JS Chen. JS Reid. P J. Pokela, and MA Nicolet, "T
antalum-based diffusion barriers in Si / Cu VLSIMeta
llizations "J. Appl. phys. 70, 1369 (1991) and JOOlo
wolate, CJ Mogab, RB Gregory, and M. Kottle, App
l. phys. 72, 4009, 1992.
And an element prevention film using TiW, TiN and TaN have been proposed.

[0006] However, the TiW can prevent the diffusion of copper up to a relatively high temperature. However, when the temperature exceeds a certain temperature, the TiW undergoes a decomposition reaction together with Si to damage the diffusion prevention film. In addition, the TiN serves as a diffusion barrier film in a relatively wide temperature range. However, at a high temperature, defects occur in crystal grain boundaries, copper is diffused, and the barrier film is damaged. However, since the electrical resistance, density, and distribution of crystal grains of the TiN prevention film change according to the deposition method and conditions, the effective temperature as a diffusion prevention film for copper is changed. Research has been conducted to add nitrogen, oxygen, and hydrogen by performing heat treatment during or after deposition to improve the characteristics of the diffusion barrier film by blocking crystal grain boundaries, but have not yet obtained good results. .

Further, the polycrystalline diffusion preventing film Ta has no chemical affinity for copper and has resistance to solid solubility, but when a certain temperature is reached, copper diffuses along the crystal grain boundaries to prevent the diffusion. The membrane is damaged. Therefore, in order to prevent the crystal grain boundary diffusion of copper, an amorphous TaSi diffusion prevention film having a relatively high crystallization temperature, in which Si is added to Ta and there is no crystal grain boundary which becomes a fast copper diffusion path, is provided. Although developed, the amorphous TaSi diffusion barrier film has a very low crystallization temperature that affects the properties of the amorphous diffusion barrier film when contacted with copper, and reacts with copper even at relatively low temperatures. A damage phenomenon of the diffusion prevention film occurs.

In order to improve the function of such an amorphous TaSi diffusion preventing film, N _2, which does not react with copper, is added to the TaSi compound, and the crystallization temperature is increased so that non-characteristics in which a crystal grain boundary does not occur is obtained. Research has been conducted to form a compound prevention film, but as described above, the crystallization temperature is lowered when contacted with copper, and the specific resistance is increased to about 1000 μΩcm, so that there are still many points to be improved.

On the other hand, in order to improve the characteristics of the diffusion prevention film in the microstructure, TiN or TaN is filled (stN).
uffing) is described in the literature "W. Sinke, GPA Frijl
ink, and FWSaris, "Oxgen in Titanium Nitride Diff
usion Barrier ", Appl. phys. Lett. 47, 471 (1995) and Kim Ki-soon," Study on the Role of TiN Diffusion Prevention Film in Copper Wiring Process ", Seoul National University Semiconductor Joint Research Institute, Report No .: ISR (94- E-1023), when an arbitrary substance is used as a diffusion barrier film, the finer the microstructure is, the more excellent the performance of the diffusion barrier film can be obtained under the same conditions, and the diffusion of copper is a diffusion barrier. It has been proven that it occurs mainly through the grain boundary of the barrier film.

As a result of experiments, the effect of preventing the diffusion of copper did not appear even when the fine structure was filled, because the heat treatment temperature was restricted in the semiconductor manufacturing process, and the crystal of the diffusion prevention film was not crystallized. This is because the grain boundary cannot be sufficiently filled from the surface to the inside.

[0011]

However, in such a conventional diffusion preventing film, TiNx, TiWx, T
When using a, TaNx, and WNx, 1 at 500 ° C.
After a lapse of time, the barrier characteristics disappear. Further, when TaSixNy or TiSixNy is used, the composition thereof changes significantly, and it is difficult to put it to practical use. Further, in the case of performing the filling treatment of the crystal grain boundary of TiN in the fine structure, since the heat treatment temperature during the semiconductor manufacturing process is limited, the filling treatment cannot be performed sufficiently from the surface of the crystal grain boundary to the inside thereof. There were disadvantages.

An object of the present invention is to form a two-layer barrier metal between a substrate and a copper film as a copper diffusion prevention film, and to form a two-layer copper diffusion prevention film capable of favorably suppressing copper diffusion. It is intended to provide a forming method.

[0013]

Means for Solving the Problems] Therefore, in the method for forming a copper diffusion preventing film having a two-layer structure between the substrate and the copper film of the present invention of claim 1, wherein the copper diffusion of the two-layer structure Prevention film and
To form a first barrier metal layer, then forming a second barrier metal layer of copper alloy material on the first barrier metal layer, the second
The barrier metal layer is formed using one of a Cu-Zn alloy, a Cu-Mg alloy, and a Cu-Ta alloy. In such a method of forming a copper diffusion prevention film having a two-layer structure, a first barrier metal layer is formed on a substrate, and a Cu—Zn alloy, a Cu—Mg alloy, and a Cu—Ta alloy are formed on the first barrier metal layer. A second barrier metal layer is formed using one of the alloys, and a copper film is deposited on the second barrier metal layer.

According to the second aspect of the present invention, the first barrier metal layer is formed to a thickness of 100 to 1000 degrees. With such a configuration, an optimal first barrier metal layer can be formed. In the invention according to claim 3, the second barrier metal layer has a thickness of 100%.
It is formed to a thickness of {1000}.

With such a configuration, an optimum second barrier metal layer can be formed. In the invention according to claim 4, specifically, the first barrier metal layer is made of TiNx, TiWx, Ta, TaN.
x, it formed using WNx, TaSixNy, and any one of TiSixNy.

According to a fifth aspect of the present invention, the second barrier metal layer is formed by using a chemical vapor deposition method or a physical vapor deposition method. In such a configuration, by using the chemical vapor deposition method, the second barrier metal layer can be formed without affecting the lower layer structure.
The second barrier metal layer contamination excellent in less contact resistance by using the physical vapor deposition is obtained.

[0017] When the Cu-Zn alloy, as claimed in claim 6, wherein the content of Zn is 88 over 97 wt. It is good to be%. In such a configuration, Ru can best second barrier metal layer is formed when using the Cu-Zn alloy.

[0018] For the Cu-Mg alloy, as claimed in claim 7 wherein, the content of Mg 43.4wt. %. With such a configuration, an optimal second barrier metal layer can be formed when a Cu-Mg alloy is used.

In the case of the Cu-Ta alloy, as claimed in claim 8, 30 wt content of Ta. %. With such a configuration, an optimal second barrier metal layer can be formed when using a Cu-Ta alloy. According to the ninth aspect of the present invention, the present invention is applied between a substrate at the time of manufacturing a semiconductor and a copper film for wiring.

With this configuration, the reliability of the copper wiring of the semiconductor element is improved.

[0021]

Embodiments of the present invention will be described below. First, the present invention provides low resistance and excellent EM
In order to satisfactorily suppress the rapid diffusion of copper having a property, a copper diffusion prevention film having a two-layer structure is formed on a substrate using a copper alloy having a stable composition. In particular, when copper is diffused in a copper alloy, the diffusion of copper is suppressed by using a property requiring a large amount of energy.

At this time, the copper alloy used is Eric
A. Brandes' edited “SmithellsMetals Reference
As presented in Book ", without reducing the resistance Cu-Zn alloy having a stable phase, Cu -Mg alloy, or C
A u-Ta alloy is used. 2 and 3 show Cu-Z
n alloys, shows a equilibrium diagram of a specific composition of Cu -Mg alloy.

In FIG. 2, α phase, β phase, β 'phase, γ phase, δ
Phase, ε-phase and η-phase are characters indicating the name of each phase area.
You. And, as shown in FIG. 2, the Cu—Zn alloy
88-97 Zn coexisting with Zn ₂ Cu and ε phase + η phase
wt. A% have copper alloy, as shown in FIG. 3, C
In the u- Mg alloy, Mg coexisting with Mg ₂ Cu and Mg is 43.4 wt. % Or more of copper alloy. Although not shown, the Cu—Ta alloy has a content of 30 wt. % Or more of copper alloy.

According to the present invention, using such a copper alloy,
In the method of forming a diffusion prevention film having a layered structure, as shown in FIG. 1, a step of forming a first barrier metal layer 102 on a substrate 100 and a step of forming the above-described copper alloy on the first barrier metal layer 102 Forming a second barrier metal layer 104 made of
And a step of depositing a copper film 106 on the second barrier metal layer 104.

That is, first, TiNx, T
The first barrier metal layer 102 is formed to a thickness of 100 to 1000 using one of iWx, Ta, TaNx, WNx, TsSixNy, and TiSixNy. Thereafter, Cu-Zn alloy on the first barrier metal layer 102, Cu
Any one of a Mg alloy and a Cu-Ta alloy by chemical vapor deposition (CVD) or physical vapor deposition (PVD);
The second barrier metal layer 104 is formed by using
A copper diffusion preventing film having a thickness of 0 ° and having a two-layer structure in which a first barrier metal layer 102 and a second barrier metal layer 104 of a Cu alloy are stacked is formed on the substrate 100. The chemical vapor deposition method uses a chemical gas, and can form a thin film of the second barrier metal layer 104 without affecting the underlying structure. In addition, since the physical vapor deposition method utilizes physical energy, for example, a sputtering method is generally used. In this case, a sufficiently low temperature (25 ° C.
(35 ° C.), so that the second barrier metal layer 104 with little contamination and excellent contact properties can be formed.

Next, a metal-organic chemical vapor deposition method is applied on the second barrier metal layer 104.
position; MOCVD) copper diffusion preventing film having a two-layer structure engaging Ru deposition to the present invention a Cu film 106 by using a is formed. As described above, when the copper diffusion barrier film having the two-layer structure is formed, when the copper film is deposited on the second barrier metal layer 104, even if copper attempts to diffuse into the second barrier metal of the copper alloy, a large amount of copper is prevented. Since energy is required, diffusion of copper is suppressed.

In this embodiment, the method for forming a copper diffusion preventing film having a two-layer structure has been described in the case of manufacturing a semiconductor device. However, the present invention is not limited to a semiconductor device and may be used for other purposes. it can.

[0028]

As described above, according to the method for forming a copper diffusion preventing film having a two-layer structure according to the present invention, a second barrier metal layer of a copper alloy is laminated on a first barrier metal layer. Since a copper diffusion prevention film having a layered structure is formed, copper diffusion during copper deposition can be suppressed to about twice or more as compared with a conventional single-layer copper diffusion prevention film.

According to the second and third aspects of the present invention, an optimum copper diffusion preventing film can be formed. According to the fifth aspect of the present invention, by using the chemical vapor deposition method, the second barrier metal layer can be formed without affecting the lower layer structure. The second barrier metal layer contamination excellent in less contact resistance by using the physical vapor deposition is obtained. According to the inventions described in claims 6 to 8 , an optimum second barrier metal layer can be formed when each of the copper alloys is used.

[0030] As the invention of claim 9, wherein, when applied between the substrate during semiconductor device fabrication and interconnection copper film, there is an effect that can improve the reliability of the copper wiring in a semiconductor device.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view showing one embodiment of a copper diffusion preventing film structure according to the present invention.

FIG. 2 is an equilibrium diagram of a component composition of a Cu—Zn alloy for forming a second barrier metal layer.

FIG. 3 is an equilibrium diagram of a component composition of a Cu—Mg alloy for forming a second barrier metal layer.

[Explanation of symbols]

 Reference Signs List 100 substrate 102 first barrier metal layer 104 second barrier metal layer 106 copper film

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Don Wong Kim South Korea, Seoul, Eunpyung, Burgwan-dong, 245-111 -1 (72) Inventor Sa Kyung La Republic of Korea, Seoul, June Land, Mun Mok-dong, 161-6 (72) Inventor Seung Yoon Lee South Korea, Seoul, Yongsan-Kul, Cal Wal-Dong, 14-24 (72) Inventor Kyun Il Lee, Republic of Korea, Seoul, Kangdong-ku, Duncheon-dong, 54 (56) References JP-A-7-235538 (JP, A) (58) Fields investigated (Int. Cl. ⁶⁾ , DB name) H01L 21/3205 H01L 21/3213 H01L 21/768 H01L 21/28-21/288 H01L 29/40-29/51

Claims (9)

(57) [Claims] 1. A method for forming a copper diffusion prevention film having a two-layer structure between a substrate and a copper film, the copper diffusion prevention film having a two-layer structure, the first barrier metal layer being used as the copper diffusion prevention film having the two-layer structure. Then, a second barrier metal layer made of a copper alloy material is formed on the first barrier metal layer, and the second barrier metal layer is formed of Cu-Z
A method for forming a copper diffusion prevention film having a two-layer structure, wherein the method is formed by using any one of an n alloy, a Cu-Mg alloy, and a Cu-Ta alloy. 2. The method according to claim 1, wherein the first barrier metal layer has a thickness of 100 ° to 10 °.
2. The method for forming a copper diffusion prevention film having a two-layer structure according to claim 1, wherein the copper diffusion prevention film is formed to a thickness of 00 °. 3. The method according to claim 1, wherein the second barrier metal layer has a thickness of 100 ° to 10 °.
3. The method for forming a copper diffusion prevention film having a two-layer structure according to claim 1, wherein the copper diffusion prevention film is formed to a thickness of 00 °. 4. The first barrier metal layer is formed of TiNx, TiW.
x, Ta, TaNx, WNx, TaSixNy, and T
4. The method according to claim 1, wherein the first electrode is formed using any one of iSixNy.
3. The method for forming a copper diffusion prevention film having a two-layer structure according to any one of 3. 5. The formation of the copper diffusion prevention film having a two-layer structure according to claim 1, wherein the second barrier metal layer is formed by using a chemical vapor deposition method or a physical vapor deposition method. Method. 6. The Cu—Zn alloy has a Zn content of 8%.
8-97 wt. 2. The method for forming a copper diffusion preventing film having a two-layer structure according to claim 1. 7. The Cu—Mg alloy has a Mg content of 4%.
3.4 wt. %. The method for forming a copper diffusion prevention film having a two-layer structure according to claim 1. 8. The Cu—Ta alloy has a Ta content of 3%.
0 wt. %. The method for forming a copper diffusion prevention film having a two-layer structure according to claim 1. 9. The method for forming a copper diffusion prevention film having a two-layer structure according to claim 1, wherein the method is applied between a substrate and a copper film for wiring at the time of manufacturing a semiconductor.