JPH0786285A - Wiring pattern and method of forming the same - Google Patents

Abstract

(57) [Summary] [Object] The present invention forms a sidewall protective film made of a metal nitride on the sidewall thereof without increasing the resistance of a copper-based metal pattern to be formed during etching. To form an antioxidant film. [Structure] The wiring pattern 1 is composed of a copper-based metal pattern 11 and an antioxidant film 12 formed on a side wall of the copper-based metal pattern 11 and made of a metal nitride film or a metal oxynitride film. The formation method is
When etching a copper-based metal layer using an etching gas containing a gaseous metal chloride, a nitrogen-based gas, and a chlorine-based gas, a copper-based metal pattern 11 formed by the copper-based metal layer 11
The copper-based metal layer is etched while depositing a metal nitride on the side wall of the. Then, a nitriding process is performed to modify the metal nitride of the sidewall protective film into a denser metal nitride than before the nitriding process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring pattern used for forming a wiring or an electrode of a semiconductor device and a method for forming the wiring pattern.

[0002]

2. Description of the Related Art Copper wiring materials, which have lower resistance and higher electromigration resistance than aluminum-based metals, have been attracting attention as wiring materials for ULSIs and filling materials for connection holes. In order to put the copper wiring into practical use, etching and oxidation prevention of the copper layer for forming the copper wiring are important issues.

For etching the copper layer, an etching gas containing halogen [eg, at least one of chlorine (Cl), fluorine (F), bromine (Br) and iodine (I)] is used. Chlorine, which forms copper chloride (CuCl _x ) having a high vapor pressure among copper halides produced by etching, is used as an etching gas.

In particular, by using a mixed gas of silicon tetrachloride (SiCl ₄ ), chlorine (Cl ₂ ), nitrogen (N ₂ ) and ammonia (NH ₃ ), nitridation is performed on the sidewall of the copper pattern formed during etching. A side wall protective film made of a silicon film is formed. Therefore, since the side etching of the copper pattern is suppressed, the copper pattern having excellent anisotropy is formed.

As a method of preventing the oxidation of the copper pattern, titanium is previously formed in the copper layer when the copper layer is formed in advance.
Add impurities such as aluminum. In this way, after forming a copper pattern from the copper layer to which impurities have been added, heat treatment is performed to deposit titanium or aluminum on the surface of the copper pattern. Then, a method of forming an antioxidant film made of titanium nitride or aluminum oxide has been proposed.

A method for reducing the copper oxide layer by hydrogen annealing has also been proposed. That is, it is a method of reacting oxygen and hydrogen in the copper oxide layer to generate H ₂ O.

[0007]

However, when the silicon nitride film is used as the sidewall protection film, the silicon in the silicon nitride penetrates into the copper wiring to increase the resistance of the copper wiring. Further, oxygen penetrates into the copper wiring through the silicon nitride film, so that the copper wiring is oxidized. This also increases the resistance of the copper wiring.

In the above forming method, since titanium or aluminum is added to the copper layer, the copper wiring formed of the copper layer has a higher resistance than the copper wiring formed of the pure copper layer.

The method of reducing the copper oxide layer by hydrogen annealing is effective when the copper oxide layer is thin, but it is difficult to reduce all the oxide layer when the oxide layer is thick. . Even if it can be reduced, voids remain in the portion of the copper layer where oxygen has escaped, so that the wiring resistance becomes higher than that before the hydrogen annealing treatment.

An object of the present invention is to provide a wiring pattern in which an antioxidant layer is formed on a copper pattern including a copper wiring, a copper electrode and the like and a method for forming the same without increasing resistance.

[0011]

SUMMARY OF THE INVENTION The present invention is a wiring pattern and a method for forming the wiring pattern, which are made to achieve the above object. That is, the wiring pattern is composed of a copper-based metal pattern and an anti-oxidation film made of a metal nitride film or a metal oxynitride film provided on the side wall thereof.

As a method of forming the copper-based metal layer, when the copper-based metal layer is etched using an etching gas containing a gaseous metal chloride, a nitrogen-based gas, and a chlorine-based gas, the copper-based metal layer is formed. The copper-based metal layer is etched while depositing a metal nitride on the sidewall of the copper-based metal pattern. The gaseous metal chloride comprises at least one of aluminum chloride, titanium chloride, zirconium chloride, molybdenum chloride, tantalum chloride and tungsten chloride.

After the etching of the copper-based metal layer is completed, it is exposed to an atmosphere containing oxygen to modify the side wall protective film made of metal nitride deposited on the side wall into a metal oxynitride, and thus an antioxidant film. To form.

After the above etching treatment, by nitriding treatment, the side wall protective film made of metal nitride deposited on the side wall is reformed into a denser metal nitride than the metal nitride before nitriding treatment, and then oxidized. Forming a barrier film.

The etching mask made of silicon oxide, silicon nitride, silicon carbide, or silicon nitride oxide used for the above etching is removed by wet etching or used as a part of the interlayer insulating film.

[0016]

In the above wiring pattern, since the oxidation preventing film made of the metal nitride film or the metal oxynitride film is formed on the side wall of the copper-based metal pattern, the copper-based metal pattern is prevented from being oxidized.

In the above forming method, when the copper-based metal layer is etched using the etching gas containing the gaseous metal chloride, the nitrogen-based gas, and the chlorine-based gas, the copper formed by the copper-based metal layer is etched. While depositing the metal nitride on the side wall of the metal-based pattern, etching the copper-based metal layer,
A sidewall protection film is formed on the sidewall of the copper-based metal pattern formed by etching.

As the gaseous metal chloride, at least one of aluminum chloride, titanium chloride, zirconium chloride, molybdenum chloride, tantalum chloride and tungsten chloride is used.
At a temperature of about ℃ to 350 ℃, each metal chloride is dissociated into metal and chlorine (Cl ₂ ). Therefore, a silicon-based inorganic mask that withstands the dissociation temperature is used as the etching mask. Then, the metal generated by the dissociation reacts with nitrogen of the nitrogen-based gas to generate a metal nitride. Then, metal nitride is deposited on the sidewalls of the formed copper-based metal pattern to form the sidewall protection film.

After the etching of the copper-based metal layer is completed, the copper-based metal layer is exposed to an atmosphere containing oxygen to modify the metal nitride deposited on the side wall into a metal nitride oxide. From this, for example, when etching is performed using gaseous aluminum chloride, gaseous titanium chloride or gaseous zirconium chloride, the sidewall protective film is formed of aluminum nitride oxide, titanium nitride oxide or nitride. Becomes zirconium oxide. Aluminum oxide, titanium oxide, and zirconium oxide have a larger free energy of formation on the negative value side than copper oxide, and thus serve as a stable antioxidant film.

After performing the above etching treatment, the metal nitride deposited on the side wall is reformed into a denser metal nitride than that before the nitriding treatment by the nitriding treatment, so that the side wall protective film becomes a dense metal nitride film. Therefore, it also serves as an antioxidant film.

Since the etching mask made of silicon oxide, silicon nitride, silicon carbide or silicon oxynitride used for the above etching is removed by the wet etching process, the formed sidewall protection film does not deteriorate into an oxide film. Since the etching mask is used as a part of the interlayer insulating film, the etching mask removing step is omitted.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the schematic sectional view of FIG.

As shown in FIG. 1, the wiring pattern 1 is formed on a substrate 21 and basically consists of a copper-based metal pattern 11 and a metal nitride film or metal oxynitride film provided on the side wall thereof to prevent oxidation. And the membrane 12.

Usually, as shown in the figure, a barrier metal layer 13 made of titanium nitride (TiN) is formed on the lower surface side of the copper-based metal pattern 11. An antireflection layer 14 made of titanium nitride (TiN) is formed on the upper surface side of the copper-based metal pattern 11. Therefore, the antioxidant film 12 is formed on the sidewalls of the barrier metal layer 13 and the antireflection layer 14.

The copper-based metal pattern 11 is preferably made of pure copper. The metal nitride film includes aluminum nitride (AlN _x ), titanium nitride (TiN _x ),
It is made of zirconium nitride (ZrN _x ), molybdenum nitride (MoN _x ), tantalum nitride (TaN _x ), or tungsten nitride (Wn _x ). The metal oxynitride film is made of aluminum oxynitride (AlO _x N _y ),
It is made of titanium nitride oxide (TiO _X N _Y ) or zirconium nitride oxide (ZrO _X N _Y ).

The concept of the wiring pattern 1 in the above description includes all the patterns that can be formed by copper-based metal patterns such as electrodes, characteristic test pads, bonding pads, etc., in addition to ordinary wiring. The wiring pattern 1 is RA
The present invention can be applied to memory products such as M and ROM, logic products, semiconductor devices such as gate arrays, electronic devices such as thin film magnetic heads, thin film coils, and thin film inductors.

In the wiring pattern 1, since the anti-oxidation film 12 made of the metal nitride film or the metal oxynitride film is formed on the side wall of the copper-based metal pattern 11, the anti-oxidation film 12 oxidizes the copper-based metal pattern. Protected from

Next, referring to FIG.
Will be described with reference to the forming process chart.

As shown in FIG. 2A, the barrier metal layer 13 made of titanium nitride (TiN) is formed on the substrate 21.
Is formed with a film thickness of, for example, 30 nm to 100 nm. Further, on the upper surface thereof, a copper-based metal layer 22 made of pure copper is formed by a sputtering method or a CVD method. Furthermore, on the upper surface of the copper-based metal layer 22, titanium nitride (T
The antireflection layer 14 made of iN) has a thickness of, for example, 30 nm to 1
It is formed to a film thickness of 00 nm.

Then, as shown in FIG. 2B, the antireflection layer 14 is formed by a usual etching mask forming method.
An etching mask 15 is formed at a predetermined position above. The etching mask 15 is formed by forming a silicon-based film (for example, a film made of silicon oxide, silicon nitride, silicon oxynitride, or silicon carbide) on the antireflection layer 14 by the CVD method, and then performing the lithography technique and etching. An etching mask 15 made of a silicon-based film is formed.

Next, the antireflection layer 14, the copper metal layer 22 and the barrier metal layer 13 are etched using an etching gas containing a gaseous metal chloride, a nitrogen gas and a chlorine gas.

The above-mentioned gaseous metal chlorides include aluminum chloride (AlCl _x ) and titanium chloride (TiC).
l _x ), zirconium chloride (ZrCl _x ), molybdenum chloride (MoCl _x ), tantalum chloride (TaC)
1 _x ) and tungsten chloride (WCl _x ) are used. For nitrogen-based gas,
For example, ammonia (NH ₃ ) and nitrogen (N ₂ ) are used. For example, chlorine (Cl ₂ ) is used as the chlorine-based gas.

As an example of the etching conditions, chlorine with a flow rate of 20 sccm to 50 sccm, the gaseous metal chloride with a flow rate of 10 sccm to 50 sccm, ammonia with a flow rate of 5 sccm to 20 sccm, and a flow rate of 10 sccm to A mixed gas with 100 sccm of nitrogen is used. The flow rate of each gas is appropriately selected within the range shown above. Moreover, the pressure of the etching atmosphere is 1 Pa.
~ 5 Pa, the temperature of the etching atmosphere is 200 ℃ ~ 3
The RF power is set to 50 W to 300 W at 50 ° C. The temperature may be at least a temperature at which the metal chloride maintains a gas state.

In the etching, metal chloride (MCl
_X ) reacts with ammonia (NH ₃ ) to form a metal nitride (MN _X ). Then, as the etching of the copper-based metal layer 22 proceeds, the metal nitride is deposited on the sidewalls of the formed copper-based metal pattern 11 to form the sidewall protection film 23. The reaction at this time is as follows.

[0035]

## EQU1 ## MCl _X + NH ₃ → MN _X + HCl + Cl radical (1)

The side wall protective film 23 of the metal nitride deposited on the side wall prevents the side attack of the copper-based metal pattern 11 by the chlorine radical Cl *.

Then, as shown in FIG. 2C, the antireflection layer 14, the copper-based metal pattern 11, the barrier metal layer 13 are formed.
Side wall protection film 2 made of metal nitride deposited on each side wall of
3 is formed.

In the above forming method, when the copper-based metal layer 22 is etched by using the etching gas containing the gaseous metal chloride, the nitrogen-based gas and the chlorine-based gas, the copper-based metal layer 22 is formed. Since the copper-based metal layer 22 is etched while depositing a metal nitride on the sidewall of the copper-based metal pattern 11, the sidewall protection film 23 is formed on the sidewall of the copper-based metal pattern 11 formed by the etching. It

At that time, the gaseous metal chlorides include aluminum chloride (AlCl _x ) and titanium chloride (Ti).
Cl _x ), zirconium chloride (ZrCl _x ), molybdenum chloride (MoCl _x ), tantalum chloride (TaCl
_X ) and tungsten chloride (WCl _x ), at least one of the above metal chlorides contains metal and chlorine (Cl ₂ ) at a temperature of about 200 ° C. to 350 ° C.
Dissociated into and. Therefore, as the etching mask 15, a silicon-based inorganic mask having heat resistance is used. Then, the metal generated by the dissociation and the nitrogen of the nitrogen-based gas react with each other to generate a metal nitride, which is deposited on the sidewall of the formed copper-based metal pattern to form the sidewall protection film 23.

Then, as shown in FIG. 3, as nitriding treatment, nitriding annealing is performed in a mixed gas atmosphere of ammonia (NH ₃ ) and nitrogen (N ₂ ), an ammonia (NH ₃ ) gas atmosphere or a nitrogen (N ₂ ) gas atmosphere. Perform processing. The nitriding annealing treatment, a metal nitride and further nitriding the side wall protective film (23) consisting of (MN _X), modified into a stable metal nitride (MN _X). In this way, the side wall protective film (23) becomes the antioxidant film 12.

In the above-mentioned nitriding treatment, since the side wall protective film 23 is modified to be a denser metal nitride than the metal nitride before the nitriding treatment, the side wall protective film (23) has an antioxidant property. .

Alternatively, when aluminum chloride, titanium chloride or zirconium chloride is used as an etching gas in the etching of the copper-based metal layer 22, as shown in FIG. 4, the side wall protective film 23 is made of aluminum nitride. , Titanium nitride or zirconium nitride. The side wall protection film 23 made of such a metal nitride is exposed to an atmosphere containing oxygen (O ₂ ) to remove aluminum nitride oxide (Al
O _X N _Y ), titanium nitride oxide (TiO _X N _Y ), or zirconium nitride oxide (ZrO _X N _Y ). The atmosphere containing oxygen (O ₂ ) is, for example, the atmosphere.

In general, aluminum oxide, titanium oxide and zirconium oxide have a larger free energy of formation on the negative value side than copper oxide. Therefore, the generated aluminum nitride oxide (AlO _X N _Y ), titanium nitride oxide (TiO _X N _Y ) or zirconium nitride oxide (ZrO _X N _Y ) becomes the stable antioxidant film 12.

Then, as shown in FIG. 5, the etching mask 15 (the portion indicated by the chain double-dashed line) is removed. Since the etching mask 15 is formed of silicon oxide, silicon nitride, silicon carbide, or silicon nitride oxide, the etching mask 15 is removed by wet etching treatment.

In the above wet etching, for example, hydrofluoric acid or phosphoric acid is used. However, since hydrofluoric acid etches a titanium-based material, phosphoric acid is used when the sidewall protective film 23 is made of a titanium-based material. Further, since phosphoric acid etches an aluminum-based material, hydrofluoric acid is used when the sidewall protective film 23 is formed of an aluminum-based material.

In the above removing method, the etching mask 15 is removed without changing the formed sidewall protection film 23 into an oxide film.

Alternatively, the etching mask 15 may be used as a part of the interlayer insulating film without removing it.

That is, as shown in (1) of FIG. 6, a silicon oxide film 32 is formed by CVD, for example, so as to cover the entire surface on the side of the etching mask 15. Then, anisotropic etching is performed to remove the portion indicated by the chain double-dashed line of the silicon oxide film 32, and leave the remaining silicon oxide film (3
In 2), the sidewall insulating film 33 is formed on the sidewall side of the wiring pattern 1. At this time, the silicon oxide film (32) may be left on the substrate 21 or the etching mask 15.

Then, as shown in FIG. 6B, SO is applied by a coating technique so as to cover the entire surface of the wiring pattern 1 side.
A G (Spin on glass) film 34 is formed. Then, heat treatment is performed to stabilize the SOG film 34. As described above, the etching mask 15 and the sidewall insulating film 33 are formed.
And an SOG film 34 are formed to form an interlayer insulating film 31.

Alternatively, a silicon oxide film 32 is formed by the CVD method so as to cover the entire surface on the etching mask 15 side, and the silicon oxide film 32 and the etching mask 1 are formed.
It is also possible to use 5 and 5 as the interlayer insulating film 31. The method for forming the interlayer insulating film 31 is an example, and the method is not limited to the above method, and any method may be used as long as the etching mask 15 is used for the interlayer insulating film 31.

The numerical values and numerical ranges described in the above embodiments are examples, and the values are not limited to those values.

[0052]

As described above, the wiring pattern of the present invention is not oxidized because the anti-oxidation film made of the metal nitride film or the metal oxynitride film is formed on the side wall of the copper-based metal pattern. Therefore, it is possible to reduce the resistance of the wiring.

In the above-described forming method, the copper-based metal layer is etched using an etching gas containing a gaseous metal chloride, a nitrogen-based gas, and a chlorine-based gas, so that the sidewall of the copper-based metal pattern to be formed is etched. The copper-based metal layer is etched while depositing the metal nitride. For this reason, since the side wall protective film is formed on the side wall of the copper-based metal pattern, the side wall can be protected from the side attack of chlorine radicals during etching. Therefore, it becomes possible to obtain an etching shape having excellent anisotropy.

As the metal chloride, aluminum chloride,
Since at least one of titanium chloride, zirconium chloride, molybdenum chloride, tantalum chloride, and tungsten chloride is used, the temperature is 200 ° C to 350 ° C.
At moderate temperatures, metal chlorides can be dissociated into metal and chlorine (Cl ₂ ). Therefore, the etching mask can be formed of a silicon-based inorganic material corresponding to the dissociation temperature.

Since the metal nitride is reformed into the metal nitride oxide by exposing it to the atmosphere containing oxygen, the side wall protective film becomes the metal nitride oxide. Therefore, it is possible to form the sidewall protective film made of aluminum nitride oxide, titanium nitride oxide, or zirconium nitride oxide, which has a larger free energy of formation than the oxide of copper on the negative value side. Therefore, it becomes possible to form a stable antioxidant film with the sidewall protection film.

By performing the nitriding treatment, the metal nitride of the side wall protective film can be reformed into a denser metal nitride than before the treatment. Therefore, the antioxidant performance can be improved.

Since the etching mask made of silicon oxide, silicon nitride, silicon carbide or silicon nitride oxide is removed by the wet etching process, the side wall protective film is not transformed into an oxide film. Therefore, the sidewall protection film can have an antioxidant function.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a wiring pattern of the present invention.

FIG. 2 is a process drawing of forming a wiring pattern.

FIG. 3 is an explanatory diagram of formation of an antioxidant film.

FIG. 4 is an explanatory diagram of formation of an antioxidant film.

FIG. 5 is an explanatory diagram of etching mask removal.

FIG. 6 is a process drawing of an interlayer insulating film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wiring pattern 11 Copper-based metal pattern 12 Antioxidation film 15 Etching mask 22 Copper-based metal layer 23 Sidewall protection film 31 Interlayer insulation film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/88 D

Claims (6)

[Claims] 1. A wiring pattern comprising a copper-based metal pattern and an anti-oxidation film made of a metal nitride film or a metal oxynitride film provided on a sidewall of the copper-based metal pattern. 2. A copper-based metal pattern formed by the copper-based metal layer when the copper-based metal layer is etched using an etching gas containing a gaseous metal chloride, a nitrogen-based gas, and a chlorine-based gas. A method for forming a wiring pattern, characterized in that the copper-based metal layer is etched while depositing a metal nitride on the side wall of. 3. The method for forming a wiring pattern according to claim 2, wherein the gaseous state comprises at least one of aluminum chloride, titanium chloride, zirconium chloride, molybdenum chloride, tantalum chloride and tungsten chloride. When etching the copper-based metal layer using an etching gas containing a metal chloride, a nitrogen-based gas, and a chlorine-based gas, a metal nitride is formed on the sidewall of the copper-based metal pattern formed by the copper-based metal layer. A method for forming a wiring pattern, characterized in that the copper-based metal layer is etched while being deposited. 4. The method for forming a wiring pattern according to claim 2 or 3, wherein after the etching of the copper-based metal layer is completed, the copper-based metal layer is exposed to an atmosphere containing oxygen to remove the metal nitride deposited on the side wall. A method for forming a wiring pattern, characterized in that the side wall protective film is modified into a metal nitride oxide. 5. The method of forming a wiring pattern according to claim 2, wherein after the etching of the copper-based metal layer is completed, a sidewall protection film made of metal nitride deposited on the sidewall is subjected to nitriding treatment. A method for forming a wiring pattern, characterized in that the metal nitride is modified to be denser than the metal nitride before nitriding. 6. The method for forming a wiring pattern according to claim 2, claim 3, claim 4, or claim 5, wherein the silicon oxide, silicon nitride, silicon carbide, or oxynitride used in the etching of the copper-based metal layer is used. A method for forming a wiring pattern, characterized in that an etching mask made of silicon is removed by wet etching or used as a part of an interlayer insulating film.