JP2500435B2 - Dry etching method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching method used in a semiconductor manufacturing process for electronic devices and the like.

[0002]

2. Description of the Related Art In recent LSI technology, miniaturization
While the dry etching progresses, the current density for fine wiring
Increase inevitable
The subject has become apparent. Addressing this issue, wiring reliability
Si and Cu are added to aluminum to improve the property
Is being attempted. For further miniaturization
Has higher migration resistance than conventional Al alloy film
In addition, studies on Cu wiring with low wiring resistance have also been made.
There is. When processing a Cu film, a chlorine-based gas is generally used.
Dry etching using CuCl_XSteam of
Since the pressure is low, raise the substrate temperature to 250 ° C or higher
Etching is performed. On the other hand, with miniaturization, DR
[Pb (ZrTi) O is added to the capacity part of AM and FRAM. ₃]
Membrane, [BaSrTiO 3₃] Film, [SrTiO 3₃] High film
The use of Pt for the dielectric film and the capacitor electrode film has been studied.
ing. In order to process these films, milling etc.
Sputter-etched, but submicron
There is no means for performing the following fine processing. Furthermore, YBa
CuO_XSimilar fine processing for oxide superconducting films such as
However, this effective means has not been found.

[0003]

The etching of the Cu film is performed by using a chlorine-based gas and raising the substrate temperature to 250 ° C. or higher. In this case, since a normal photoresist mask has no heat resistance, a mask material having high heat resistance such as a nitride film must be used.
Further, etching at a high temperature makes it difficult to suppress side etching, and easily causes after-corrosion (corrosion after etching), which causes disconnection of wiring and lowers reliability. Next, Pt
The film, the high dielectric film and the oxide superconducting film can be processed by using sputter etching such as milling.
It is difficult to perform fine processing of submicron or less. Further, in milling, a sidewall film adheres to the side surface of the mask, and it is extremely difficult to remove it after etching. It is an object of the present invention to provide a dry etching method that can solve such conventional problems.

[0004]

The first object of the present invention is to provide a method of dry etching a transition metal film, an alkaline earth metal film, or a film containing a transition metal or an alkaline earth metal, wherein a halogen compound of a group III metal is used. It is a dry etching method characterized in that it is used as an etching gas. A second aspect of the present invention is a dry etching method for a transition metal film, wherein a transition metal film containing a transition metal or a group III metal having a low melting point of a halogen compound is used as the transition metal film. .
A third aspect of the present invention is a wiring material comprising a transition metal film containing a transition metal or a group III metal having a low melting point of a halogen compound.

In the present invention, the film containing a transition metal or an alkaline earth metal is [Pb (ZrTi)].
Examples thereof include high dielectric films such as O ₃ ] films, [BaSrTiO ₃ ] films and [SrTiO ₃ ] films, and films containing transition metals such as oxide superconducting films such as YBaCuO _x and alkaline earth metals.
Further, examples of the halogen compound of the group III metal, which is the etching gas, include aluminum chloride and gallium chloride. Further, a transition metal film such as Cu having a high melting point of a halogen compound has a low melting point of a halogen compound in the film Z.
Dry etching is performed as a metal film to which n or another transition metal or a group III metal such as Al is added. According to any of these etching methods, a metal complex is formed during etching, and as a result, etching species can be volatilized at a relatively low temperature.

[0006]

When a Cu film which is a transition metal film is dry-etched, chlorine gas has conventionally been used.
By etching using a chlorine gas containing a group III metal such as gallium chloride or aluminum chloride, CaCl ₄ ²⁻ · Cu ²⁺ or AlCl ₄ ²⁻ which is one of metal complexes is etched.
Since the Cu ²⁺ is formed, the Cu film can be etched at a relatively low temperature. Therefore, the etching temperature around 250 ° C., which is conventionally required, can be lowered to about 100 ° C.

Also, the melting point of CuCl ₂ which is a chloride of Cu is 620 ° C.
Cl melting point: 190 ° C.), Zn (ZnCl ₂ melting point: 2)
(83 ° C.) and the like, when dry etching is performed with a chlorine-based gas, addition of Zn or Al promotes desorption of CuCl _x , and volatilization can be performed at a relatively low temperature. For example, a film in which Zn is added to a Cu film has an α state of 3 in Cu in the range of 100 ° C to 500 ° C.
When a solid solution of about 5% is made and etching is performed with a Cl-based gas,
Since ZnCl ₄ ²⁻ · Cu ²⁺ having a relatively low melting point is formed, Cu desorption can be assisted. In this case, C
Even if Zn is added to the u film, Zn has substantially the same mass number as Cu, so that electromigration and stress migration resistance do not deteriorate as compared with the Cu film, and the resistance value does not decrease so much. Thus, addition of Zn to the Cu film enables fine processing of the Cu film at a low temperature, so that etching can be performed with a photoresist mask, and side etching and after-corrosion can be suppressed. You can In addition, ECR (Electron C
yclotron Resonance) Etching and magnetron etching can be used at low pressure (about 10 ^-4 Torr) and high density plasma can be generated to further reduce desorption temperature and realize etching at low temperature (100 ° C or less). can do.

Further, the wiring material made of a transition metal film containing a transition metal or a group III metal having a low melting point of a halogen compound according to the present invention can be etched at a low temperature and, for example, Zn, Sn, Ge. Cu added with etc.
The film has a higher reflow property than pure Cu and facilitates the filling of holes. Further, since the resistance to electromigration and stress migration is higher than that of the wiring material in which Cu is added to Al, the long-term stability of the wiring is improved.

[Pb (ZrTi) O ₃ ] film, [BaSr
TiO ₃ ] film, high dielectric film such as [SrTiO ₃ ] film, YB
Even when a film containing a transition metal or an alkaline earth metal of an oxide superconducting film such as aCuO _x is dry-etched, by using a halogen compound gas of a Group III metal such as aluminum chloride or gallium chloride, Pb, Zr, Sr, B
Since the metal complex containing a and Y is formed, the etching reaction is promoted. Therefore, since the etching using the chemical reaction progresses, it becomes possible to perform fine processing of submicron or less.

[0010]

EXAMPLES Next, examples of the present invention will be described. Example 1 FIG. 1 is a sectional view of a semiconductor chip for explaining an example of Cu film etching according to the method of the present invention. FIG.
A base oxide film 2 is formed on a Si substrate 1 shown in (a) by a thermal oxidation method or a CVD method, and about 20% of Zn is added to the oxide film 2 by a sputtering method, a CVD method or an evaporation method. A Cu film 3 (500 nm) is formed. Then, a normal photoresist 4 is applied on the Cu film 3, and the resist 4 is patterned by a normal photoresist process.
Next, as shown in FIG. 1B, the Zn-added Cu film 3 is etched with chlorine gas using the resist 4 as a mask. After etching, as shown in FIG. 1C, the resist 4 is removed by oxygen gas plasma. In this case, the etching gas may be gallium chloride gas, aluminum chloride gas, or chlorine gas containing an organic metal. The mask in this case may be a two-layer resist mask (excimer laser resist / organic film) or a three-layer resist mask (EB (Electron Beam) resist / coating type oxide film / organic film). The Cu film 3 is etched by an ECR etching device or a magnetron etching device that can obtain high density plasma at low pressure (10 ⁻⁴ to 10 ⁻³ Torr).

Embodiment 2 FIG. 2 is a sectional view of a semiconductor chip for explaining an embodiment of etching a high dielectric film according to the method of the present invention. As shown in FIG. 2A, the underlying interlayer insulating film 2 is formed on the substrate 20.
1 is formed by a CVD method, and a Ta film 22 (50 nm) and a Pt film 23 are formed on the insulating film by a sputtering method or an evaporation method.
(50 nm) is formed, and the high dielectric film BaSrTiO ₃ film 24 (15) is further formed by the sputtering method, the CVD method or the vapor deposition method.
0 nm) is formed. Then, the Al electrode film 2 is formed on the film.
5 (100 nm) is formed and the oxide film 26 (300 nm) is formed.
Is formed, a normal photoresist film 27 is applied, and the resist is patterned in a normal photoresist process. Next, as shown in FIG. 2B, the oxide film 26 on the Al film is patterned by dry etching using CF ₄ and CHF ₃ gas to etch the multilayer film of the Ta film 22 to the Al film 25. Used as a mask. After patterning the oxide film mask, the resist 27 is removed by oxygen plasma ashing. Then, using gallium chloride gas, aluminum chloride gas or chlorine gas containing an organic metal as an etching gas, a multilayer film of the Ta film 22 to the Al film 25 is processed as shown in FIG. 2C. When forming this oxide film mask, a two-layer resist mask (resist for excimer laser / organic film) or a three-layer resist mask ((EB (Electron Beam) resist / coating type oxide film / organic film) may be used. The above multilayer film 22 to
When etching 25, low pressure (10 ^-4 to 10 ^-3
Torr) is performed by an ECR etching device or a magnetron etching device that can obtain high-density plasma.

[0012]

As described above, a method of using a halogen compound gas of a group III metal as an etching gas of the present invention, and a film in which a transition metal or a group III metal having a low melting point of a halogen compound is added to the film As for the method of etching, it is possible to lower the etching temperature than before, for example, it becomes possible to etch a Cu film, which was normally said to have to be etched at a high temperature of 250 ° C. or higher, at around 100 ° C. Becomes Therefore, since the photoresist can be used as a mask and side etching and after-corrosion can be suppressed, disconnection of the wiring does not occur and reliability is not deteriorated. Further, it has been considered difficult to finely process a Pt film, a high dielectric film, a transition metal film such as an oxide superconducting film, an alkaline earth metal film, or a film containing a transition metal or an alkaline earth metal. Fine processing becomes possible by the dry etching method.

[Brief description of drawings]

FIG. 1 is a sectional view of a semiconductor chip for explaining an embodiment of the present invention.

FIG. 2 is a sectional view of a semiconductor chip for explaining another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Si substrate 2 Underlayer oxide film 3 Zn added Cu film 4 Photoresist film 20 Substrate 21 Underlayer interlayer insulating film 22 Ta film 23 Pt film 24 BaSrTiO ₃ film 25 Al electrode film 26 Oxide film 27 Photoresist film

Claims (3)

(57) [Claims] 1. A dry etching method for a transition metal film, an alkaline earth metal film, or a film containing a transition metal or an alkaline earth metal, wherein a halogen compound of a group III metal is used as an etching gas. Method. 2. A dry etching method for a transition metal film, wherein a transition metal film to which a transition metal or a group III metal having a low melting point of a halogen compound is added is used as the transition metal film. 3. A wiring material comprising a transition metal film containing a transition metal or a group III metal having a low melting point of a halogen compound.