JP3189767B2 - Manufacturing method of copper wiring - 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 for manufacturing a semiconductor device, and more particularly to a method for manufacturing copper wiring used in a semiconductor integrated circuit.

[0002]

2. Description of the Related Art In recent years, the density of semiconductor integrated circuit devices such as LSIs has been further increased, and the wiring has also become finer and finer. Along with this, problems such as electromigration and stress migration have occurred in the conventionally used aluminum (Al) alloy wiring. Therefore, attention has been paid to wiring using copper, which has higher reliability and lower resistance than aluminum (Al) alloy wiring, and various research and development have been made.

For example, there is a method of coating the surface of copper wiring and the boundary with the substrate with a high melting point metal in order to suppress the surface oxidation of copper and the reaction with the surrounding silicon layer or oxide film and maintain the performance. . Further, regarding miniaturization of the wiring structure, a structure in which wiring is embedded in a groove provided in a substrate is disclosed in Japanese Patent Laid-Open No. 7-29.
No. 7186.

As a method of depositing copper for forming such fine copper wiring, there are sputtering, plating, chemical vapor deposition (CVD) and the like.
As in 186, hexafluoroacetylacetonato copper (I) trimethylvinylsilane is used as a raw material gas, and a CVD method using an organic copper compound as a raw material is often used. In this method, copper is deposited by the following disproportionation reaction (1). 2Cu (hfac) (tmvs) → Cu + Cu (hfac) 2+ (tmvs) 2 (1) where (hfac) and (tmvs) represent hexafluoroacetylacetone and trimethylvinylsilane, respectively. In this reaction, as shown in FIGS. 5A and 5B, the raw material gas 11, that is, Cu (hfac) (tmvs), which is a monovalent copper compound, is used.
Molecules exchange electrons with each other and change the valence state of copper to 0.
Valence and divalent, zero valent copper is deposited as metal,
Divalent copper and (hfac) are volatile molecules Cu (hfac) 2
Is formed and detached from the surface, and (tmvs) is detached as a volatile molecule similarly when two of them are stuck together.

[0005]

By the way, especially in the early stage of the disproportionation reaction (1), (hfac)
It is known that the decomposition of the compound easily occurs. The effect of this side reaction is described as follows in Chemistry of Metal CVD (VCH Publishing, 1994) pp. 273.
That is, as shown in FIG. 5C, at a temperature of 375 K or more, the hfac group of hexafluoroacetylacetona copper (Cu (hfac)) adsorbed on the surface of the substrate 10 partially decomposes, and as a result, decomposition products Impurity elements such as carbon, oxygen and fluorine remaining in the deposited copper.

[0006] Such an impurity element lowers the electrical properties and reliability of the copper wiring, such as lowering the purity of the deposited copper, increasing its resistivity and inhibiting grain growth. Further, in a wiring in which miniaturization is considered, such as a wiring having a groove structure disclosed in the above-mentioned known example of Japanese Patent Publication No. Hei 7-297186, the copper of the wiring has an extremely thin film shape. The formation of such a thin copper film is performed in the initial stage of the reaction (1), that is, under the condition where the above-mentioned side reaction is likely to occur. as a result,
The proportion of impurities in the volume of the deposited copper increases, and the purity of the copper decreases, causing electrical characteristics and reliability to deteriorate.

Therefore, the problem to be solved by the present invention is as follows:
With high purity it is to provide a method for producing a superior thin copper film on the electrical properties wiring.

[0008]

Method for producing a copper wiring of the present invention to solve the above problems, there is provided a means for solving] from carbon and fluorine
Method using organocopper compound having different group as raw material
Wherein said organic copperification generated by a side reaction during film formation
Fluorine-containing gas reacting with decomposition products of compound raw materials
At least at the initial stage of film formation with the organic copper compound raw material
It is characterized by being supplied simultaneously .

Further, the method for producing a copper wiring of the present invention is a CVD method using an organic copper compound having a group consisting of carbon and fluorine as a raw material, wherein a gas containing fluorine is mixed with the raw material at least at the initial stage of film formation. It is characterized by being supplied alternately.

[0010] The method for producing a copper wiring of the present invention is characterized in that a compound containing copper (I) hexafluoroacetylacetonate is used as a raw material of an organic copper compound.

[0011] In the method of manufacturing copper wire of the present invention, the
Fluorine contained in gas is generated by side reaction during film formation
Reacting with the decomposition products of the organic copper compound raw material
It is characterized by being a radical .

Further, a method of manufacturing a copper wiring according to the present invention is characterized in that hydrogen fluoride is supplied as a gas containing fluorine.

Further, the method of manufacturing a copper wiring according to the present invention is characterized in that hydrogen fluoride is supplied at 10 to 200 sccm.

The principle of operation of the present invention will be described below with reference to FIG. 1 and an example of a CVD method using hexafluoroacetylacetonacopper (I) trimethylvinylsilane (Cu (hfac) (tmvc)).

In the conventional method, a C-CO group, CF3
It is considered that the groups and the like are adsorbed on the surface of the substrate 10. On the other hand, if a gas containing fluorine is supplied simultaneously with the raw material gas 11 in the CVD method, the fluorine and the hydrogen for supplying the raw material gas contribute to the reaction. That is, the following reactions (2) to (4) occur. CF3 + F → CF4 (2) CF3 + H → CHF3 (3) C—CO + 4H → CH4 + CO (4) These reaction products CF4, CHF3, CH4,
CO is a volatile molecule and desorbs from the surface as a gas. Therefore, it is possible to eliminate the contamination of impurities in the conventional method, increase the purity of the deposited copper, and improve the electrical characteristics and reliability of the copper wiring.

When a hydrogen fluoride gas or plasma comprising fluorine and hydrogen is used, active fluorine radicals 13 and hydrogen radicals 14 are generated by decomposition of the hydrogen fluoride gas 12 as shown in FIG. as a result,
The above-mentioned reactions (2) to (4) are likely to occur, and it is possible to further enhance the effect.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

FIG. 2 shows a CV for obtaining the copper wiring of the present invention.
It is a structural diagram of D apparatus. The substrate 10 is held in the CVD chamber 20. The substrate 10 is formed by depositing a silicon oxide film of 1 μm on a Si substrate and forming a 0.5 μm deep wiring pattern groove on the oxide film surface by processing using ordinary photolithography and dry etching.
A 50 nm TiN film is deposited thereon by a sputtering method. The substrate 10 is kept at the CVD temperature of 200 ° C. At this time, the inside of the chamber 20 is evacuated to a level of 10 −7 Torr by the pump 21. Next, the liquid raw material (Cu (hfac) (tmvs)) 22 is vaporized in the vaporized gas 23 to produce a raw material gas (Cu (hfac) (tmvs)) 11.
And introduced into the chamber 20 together with the hydrogen gas 24 as a carrier gas. The supply rate of the liquid raw material 22 is set at 0.1.
4 g / min, and the flow rate of the hydrogen gas 24 is 200 sccm.
It is. At this time, the pump 21 causes the chamber 20
Is adjusted so that the internal pressure becomes 1 Torr. further,
Hydrogen fluoride (HF) gas 12 from another system
Introduce into 0. The hydrogen fluoride gas 12 is introduced as vapor from a vessel 26 containing a liquid hydrogen fluoride 50% solution 25 through a pipe 28 connected to the chamber 20 via a valve (needle valve) 27. The flow rate of the hydrogen fluoride gas 12 is 40 sccm.

The impurity distribution in the copper film of the copper wiring obtained by the above apparatus and method was measured by SIMS (secondary ion mass spectrometry), and the results are shown in FIG. In addition, as a comparative example, a copper wiring obtained by a conventional method, that is, a method without supplying hydrogen fluoride gas, was similarly measured, and the results are shown in FIG. In the copper wiring of the comparative example, the impurity concentration near the interface A with TiN as the base metal was high, and the concentration decreased as the distance from the interface increased.
On the other hand, in the copper wiring of the present invention, the impurity concentration of each of C, O and F is lower than that of the comparative example, and the difference is remarkable especially near the interface A. That is, in the present invention, an increase in impurities near the interface with the substrate is suppressed.

The above-mentioned region where impurities are likely to increase has a thickness of about 50 nm. Therefore, in a wiring in which miniaturization is considered, for example, in a wiring having a groove structure, the groove width is 0.2 μm.
When the thickness is about m, nearly half of the copper deposited in the trench becomes a region with a large amount of impurities, which is not preferable in maintaining the performance of the product. However, in the copper wiring of the present invention, the impurity concentration near the interface can be reduced, and the effect of improving the product characteristics is large.

In the above embodiment, the flow rate of the hydrogen fluoride gas was set at 40 sccm, but the same effect was obtained at a flow rate of 10 sccm or more. As the flow rate increases, the impurities in the copper decrease. However, when the flow rate is 200 sccm or more, the copper film becomes cloudy. Therefore, the supply amount of the hydrogen fluoride gas is set to 10 to 200 sccm.

Similarly, when the hydrogen fluoride gas was supplied only for the first 5 minutes, the impurity concentration near the interface also decreased. That is, the same effect can be obtained by supplying the hydrogen fluoride gas at least at the beginning of the reaction, but not throughout the copper deposition reaction.

After supplying the raw material gas for one minute, the supply is temporarily interrupted, and the hydrogen fluoride gas is supplied for 100 seconds.
The impurity concentration also decreased when the sequence of supplying at 30 cm for 30 seconds was repeated. That is, even when the hydrogen fluoride gas is supplied alternately with the source gas, the same effect as that obtained when the source gas is supplied simultaneously can be obtained.

[0023]

As described above, according to the present invention, the increase in the impurity concentration near the interface with the substrate is suppressed, so that the obtained copper wiring has low electric resistance and high reliability. In particular, the effect is great in miniaturized wiring.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the operation principle of the present invention.

FIG. 2 is a configuration diagram schematically showing an apparatus used in one embodiment of the present invention.

FIG. 3 is a diagram showing the results of one example of the present invention.

FIG. 4 is a diagram showing the results of a comparative example according to a conventional method.

FIG. 5 is an explanatory view showing the operation principle of a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Substrate 11 Raw material gas 12 Hydrogen fluoride gas 13 Fluorine radical 14 Hydrogen radical 20 Chamber 21 Pump 22 Liquid raw material 23 Vaporizer 24 Hydrogen gas 25 Liquid hydrogen fluoride 26 Liquid container 27 Valve 28 Piping

Claims (6)

(57) [Claims] 1. Organic copper having a group consisting of carbon and fluorine
This is a CVD method using a compound as a raw material,
Decomposition of the organocopper compound raw material generated by side reaction
At least the first time a film containing fluorine that reacts with
Supply at the same time as the organic copper compound raw material
A method for manufacturing a copper wiring. 2. An organic copper having a group consisting of carbon and fluorine.
A CVD method using a compound as a raw material, wherein fluorine is
Alternate gas with raw material at least at the beginning of film formation
A method for producing a copper wiring, comprising: 3. The organic copper compound raw material is hexafluoro
Using a compound containing copper acetylacetonate (I)
The copper wiring according to claim 1 or 2, wherein:
Construction method. 4. The method according to claim 1, wherein the fluorine contained in the gas is used during film formation.
Of the organic copper compound raw material generated by the side reaction of
Characterized as a fluorine radical that reacts with the product
The copper wiring according to claim 1.
Construction method. 5. The method according to claim 1, wherein the gas is hydrogen fluoride.
The copper according to any one of claims 1 to 4, wherein the copper is
Wiring manufacturing method. 6. A supply of hydrogen fluoride of 10 to 200 sccm.
The method according to any one of claims 1 to 5, wherein
13. The method for producing a copper wiring according to claim 1.