JPH1150242A - Copper sputtering target for forming electrode coating, its production and copper series electrode coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Cu series sputtering target capable of producing electrode film for semiconductors, liq. crystals, plasma displays or the like having excellent corrosion resistance and low resistivity. SOLUTION: Into a matrix essentially consisting of Cu, transition metal elemental phases which do not enter into solid solution in the matrix such as Cr, Co, Mo, W, Fe, Nb and V are dispersed. This target can be obtd. by mixing transition metal elemental powder which does not enter into solid solution in Cu and Cu powder and executing press sintering. By using the target, thin coating is formed, which is thereafter subjected to heat-treatment, by which low resistance Cu series electrode coating in which transition metal elements which do not enter into solid solution in Cu are precipitated into the Cu matrix can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor, a liquid crystal,
The present invention relates to a Cu-based sputtering target for forming an electrode film used for forming an electrode film used in a DP (plasma display) and the like, a method for manufacturing the same, and a Cu-based electrode film.

[0002]

2. Description of the Related Art When looking at the current electrode materials of various devices by product, TFT (Thin Film Tran) is used.
pure Cr as a material for forming an electrode of a liquid crystal,
Mo, W, Ta alone or an alloy thereof is employed.
Further, Al or an Al alloy is employed for forming an electrode film such as an LSI. In addition, PDP (Plasma Dis
For example, Cu and Al are employed as the wiring material of the play. In recent years, it has become unavoidable to reduce the wiring width of TFT liquid crystals as the definition of pixels increases, and the use of Al-based or Cu-based wiring materials from the above-mentioned high-melting-point metal-based wiring materials is being studied. In addition, in semiconductor devices, adoption of Cu alloy wiring has been studied along with higher integration of circuits.

[0003] Al or Al alloy wiring has a problem of disconnection due to electromigration and stress migration, and there is a problem that projections called hillocks are generated on the film surface in a heating step, and the laminated wiring is conducted. On the other hand, Cu wiring has few such problems.
Moreover, it is considered to be effective because it has a characteristic that the electric resistivity is lower than that of the Al wiring. However, Cu
The electrode film is inferior in oxidation resistance, and has a problem that oxidation proceeds in a heating step and a resistance value increases. Therefore, improvement in this point is demanded. As one of the solutions, there has been proposed a method of improving the oxidation resistance of a Cu electrode film by adding an additive element and performing alloying.

For example, it has been proposed to heat-treat a Cu—Ti alloy thin film layer formed by sputtering in a nitrogen-containing atmosphere to form a thin TiN layer on the surface of a wiring film to improve oxidation resistance. (Fourth Autumn 1988
Proceedings of the 9th Annual Meeting of the Japan Society of Applied Physics second volume 43
In addition, in Japanese Patent Application Laid-Open No. Hei 3-196419, a Cu—Zr alloy film formed by a sputtering method is coated with nitrogen or NH _3.
A method of improving oxidation resistance by forming a Zr nitride layer on the surface of a Cu wiring film by performing a heat treatment in a containing atmosphere has been proposed. Similarly, as a method of forming a nitride layer, Japanese Patent Application Laid-Open No. 3-196620 discloses a Cu—B film formed by a sputtering method.
There has been proposed a method of improving the oxidation resistance by forming a B nitride layer on the surface of a Cu wiring film by performing a heat treatment in an atmosphere containing H ₃ .

Further, after forming a Cu—Cr alloy film by a method of simultaneously depositing Cu and Cr from separate evaporation sources,
A method has been proposed in which a heat treatment is performed in a vacuum atmosphere of 10 −6 Torr or less to form a Cr oxide layer on the surface of a Cu wiring film, thereby improving oxidation resistance. This method uses a method in which Cr is dissolved in Cu as it is formed as a film.
Has the effect of separating by heat treatment and separating into a Cu layer and a Cr layer. Therefore, unlike the method of adding an element that dissolves in Cu to improve corrosion resistance, while maintaining the low resistance of Cu, corrosion resistance is improved. There is an advantage that an excellent oxide layer can be formed.

[0006]

As described above, as described above, Cu
The method using an alloy film of -Cr has an advantage that an oxide layer having excellent corrosion resistance can be formed while keeping the low resistance of Cu. The inventor of the present invention has studied this technique. As a result, Cu has a remarkably low melting point with respect to Cr (C
u: 1083 ° C., Cr: 1857 ° C.), the vapor pressures are greatly different, and it is necessary to control these two elements separately, and it is difficult to control the composition, which is a major problem in mass-producing products. It turned out to be.

On the other hand, as a method of forming a thin film, there is a sputtering method using a target.
At present, no target has been developed to form a thin film of a composition system that hardly forms a solid solution even with metals as described above and has a large difference in melting point. An object of the present invention is to provide an electrode film having excellent corrosion resistance and low resistivity with high reproducibility in view of the above problems.
An object of the present invention is to provide a system-based sputtering target, a method of manufacturing the same, and a Cu-based electrode film using the same.

[0008]

Means for Solving the Problems The present inventor has proposed Cu-Cr
A target suitable for forming an electrode film using a system in which even metals represented by the above are hardly dissolved in each other was studied. As a result, the present inventors have found that a target having a microstructure in which a transition metal element phase insoluble in Cu is dispersed using a Cu phase as a matrix has a stable film composition and a thin film with good reproducibility can be obtained. Reached.

That is, the present invention is a Cu-based sputtering target for forming an electrode film in which a transition metal element phase insoluble in the matrix is dispersed in a matrix mainly composed of Cu.

In order to ensure corrosion resistance and low resistance, the transition metal element phase is preferably composed of (Cr, Co, M
o, W, Fe, Nb, V), or one or more of single or alloy phases.

The above-described target of the present invention can be obtained, for example, by mixing a transition metal element powder insoluble in Cu and a Cu powder and subjecting the mixture to pressure sintering. By performing a heat treatment after forming a thin film using the above-described target, a low-resistance Cu-based electrode film in which a transition metal element insoluble in Cu is precipitated in a Cu matrix can be obtained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, an important feature of the present invention is that a target having a microstructure in which a transition metal element phase insoluble in Cu is dispersed using a Cu phase as a matrix. When a composition system that hardly forms a solid solution represented by the above-described Cu-Cr system is prepared by a dissolution method, the solidification region hardly has a solid solution region, and the solidification temperature of Cu and a transition metal element that is not solid-soluble in Cu significantly differs. For this reason, extreme segregation is likely to occur due to the temperature distribution of the mold, and it has been difficult to manufacture a target that can withstand practical use.

Further, a method using a composite target in which a pellet of an additive element is deposited on a Cu target to form a film was also studied. However, in this method, a compositional shift due to selective consumption of the pellet is likely to occur. There was a problem that reproducibility was poor. In contrast to such a method, the present invention employs a powder sintering method and microscopically disperses a transition metal element phase which is mainly composed of Cu and which is insoluble in Cu, so that even if the two metals are mutually metallic, Thus, a stable film composition could be obtained even in a composition system in which a solid solution hardly forms a solid solution and the melting points of the composition systems differ greatly.

The elements constituting the non-solid solution transition metal element phase that can be used as the electrode film of the present invention include, specifically,
For example, there are Cr, Mo, W, Co, Fe, Nb, and V. These elements hardly form a solid solution with Cu, can be precipitated from a Cu matrix, and can impart corrosion resistance to the electrode film. The amount of the non-solid solution transition metal element added in the present invention must be set in consideration of the specific resistance and corrosion resistance, but is preferably 2 to 20 at%.

A feature of the manufacturing method of the present invention is pressure sintering of powder. According to the pressure sintering, non-solid solution powders can be integrated with each other, and by mixing the powders, a structure can be obtained in which the transition metal element insoluble in Cu is uniformly dispersed. Specifically, as the pressure sintering method, sintering at a temperature at which Cu is not melted is necessary, and it is preferable to apply a hot isostatic pressing method capable of generating a high pressure.

[0016] The preferred sintering temperature is from 600 ° C to 105 ° C.
0 ° C, more preferably from 800 ° C to 1000 ° C.
° C. The higher the sintering pressure, the better, 100MPa
As described above, it is practically desirable to set the pressure to 200 MPa or less. By applying the above-described pressure sintering conditions, it is possible to obtain a high relative density of 99% or more with respect to the theoretical density calculated assuming that Cu and the additive element exist alone in the target. is there.

The size of the raw material powder used is preferably 500 μm or less, more preferably 200 μm or less, in order to ensure uniform dispersibility.
In the present invention, the transition metal element insoluble with Cu is C
Since it hardly diffuses into the u matrix, the particle size of the raw material particles and the size of the phase dispersed in the target structure are almost the same. By heat-treating the thin film obtained by sputtering the target of the present invention to precipitate an element that is insoluble in Cu, an electrode film having a small specific resistance can be obtained.

[0018]

An embodiment of the present invention will be described below. A Cu powder having a particle size of 100 μm or less and an additive element X powder (X: Cr, Fe, Nb) having a particle size of 200 μm or less are mixed by a rocking mixer, and a filling dimension φ133 mm × 25 mm
And kept at 400 ° C. for 1 hour while evacuating to 10 6 Pa or less to degas. Next, this was subjected to HIP (Hot Isostatic Press) at 950 ° C. and 123 MPa, and then φ100 mm × 5 by machining.
mm Cu-10at% X sintered target was obtained. Further, Cu having an average particle size of 10 μm manufactured by the electrolytic method is used.
Powder and an additive element powder X (X:
Mo, W) to obtain a Cu-10 at% X sintered target in the same manner.

FIGS. 1 to 5 show typical metal microstructure photographs of a target structure when X = Cr, Mo, W, Fe, and Nb are added elements corresponding to samples 1 to 5 of the present invention. As shown in FIGS. 1 to 5, the target of the present invention is Cu
It can be seen that the matrix has a structure in which the phase composed of the element X is uniformly dispersed.

As Comparative Example 1, there was prepared a composite target in which 12 Cr pellets of 5 mm × 5 mm × 1 mm were arranged on a Cu target of φ100 mm × 5 mm. These targets were mounted on a DC magnetron sputtering apparatus, and the gas was evacuated to a pressure of 1.0 × 10−6 Pa or less.
After performing pre-sputtering at 00 W for 30 minutes, a film having a thickness of 1 μm was formed on the cleaned glass substrate at an input power of 500 W. After the completion of the sputtering, the chamber was replaced with N ₂ gas, and the substrate was taken out. This operation was performed five times for each target, and five samples of different batches were prepared for each target. The composition of these films is
Analysis was performed by P (inductively coupled plasma emission spectroscopy). (Sample 6)

As Comparative Example 2, Cu and Cr raw materials were respectively charged into two evaporation sources in a binary vapor deposition apparatus,
After evacuation was performed at a pressure of × 10 −6 Pa or less, a film having a thickness of 1 μm was formed on the cleaned glass substrate with an input power of 500 W, and then the chamber was replaced with N ₂ gas and the substrate was taken out. This operation was performed five times, and five samples of different batches were prepared for each. The composition of these films was analyzed by ICP. (Sample 7) The above results are shown in Table 1. Further, the density of the target of the present invention was measured by an underwater displacement method. Table 2 shows the measured density values obtained by the measurement and the relative densities calculated from the theoretical densities.

[0022]

[Table 1]

[0023]

[Table 2]

As shown in Table 1, the composition variation between batches with respect to the target composition of the film formed by the sputtering target of the present invention was within ± 5%.
It can be seen that the composition of the electrode film was extremely low in compositional variation compared to the samples of Examples 2 and 2, and a highly reproducible electrode film was obtained. Further, as shown in Table 2, the target of the present invention had a relative density of 9%.
It is understood that the target has a high density of 9% or more and has few voids which cause abnormal discharge or the like during sputtering.

[0025]

According to the present invention, an electrode film having excellent corrosion resistance and low resistivity can be produced with good reproducibility.
Since a u-based sputtering target can be provided, this is an indispensable technique for practical use of various devices that require a low specific resistance electrode.

[Brief description of the drawings]

FIG. 1 is a metal microstructure photograph showing an example of a Cr-added target of the present invention.

FIG. 2 is a metal microstructure photograph showing an example of a target to which Mo of the present invention is added.

FIG. 3 is a metal microstructure photograph showing one example of a target to which W of the present invention is added.

FIG. 4 is a metal microstructure photograph showing an example of a target to which Fe of the present invention is added.

FIG. 5 is a metal microstructure photograph showing an example of a target to which Nb according to the present invention is added.

Claims (4)

[Claims] 1. A Cu-based sputtering target for forming an electrode film, wherein a transition metal element phase insoluble in the matrix is dispersed in a matrix mainly composed of Cu. 2. The transition metal element phase comprises (Cr, Co, M
o, W, Fe, Nb, V). A Cu-based sputtering target for forming an electrode film, comprising at least one element selected from the group consisting of a single substance and an alloy phase. 3. A transition metal element powder insoluble in Cu and Cu
A method for producing a Cu-based sputtering target for forming an electrode film, comprising mixing powder and sintering under pressure. 4. A Cu-based electrode film formed by the target according to claim 1.