JP2001358145A - Wiring, method of forming the same, and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of particles, in a process of etching a fine wiring layer provided with a TiN layer as an uppermost layer, using a hard mask such as SiO2. SOLUTION: A wiring laminated structure composed of the hard mask 16 like SiO2, the TiN layer 14, and a thin Ti layer 15 which is interposed between the mask 16 and the TiN layer 14 and is less likely to be etched by etching gas, such as fluorocarbon gas than the TiN layer 14 is adopted, so that a wiring can be formed, preventing a TiF compound which is low in vapor pressure adheres to the inner wall of a chamber, to cause particles to be generated or re-adheres to a wafer to generate etching residues.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring using a hard mask which has recently been put into practical use in a wiring forming process of a semiconductor manufacturing process, and a method of forming the wiring.

[0002]

2. Description of the Related Art With the progress of miniaturization of semiconductor element patterns on a semiconductor integrated circuit to 0.25 μm or less, the wavelength of a light source used in an exposure apparatus for photolithography has been shortened, and a lens aperture ratio of the exposure apparatus has been reduced. As the so-called NA value is improved, the depth of focus is becoming increasingly shallow. In accordance with this, in order to obtain the precision of the pattern dimension and the good patterned cross section of the resist, it is required to reduce the resist film thickness.

In the dry etching of wiring such as aluminum on a semiconductor integrated circuit, a resist has conventionally been used as an etching mask. However, as the resist becomes thinner, a technique using a silicon oxide film or the like as an etching mask is used.
(A silicon oxide film or the like is generally called an etching mask as a hard mask) is being put to practical use. This is because when using only a resist as in the past and reducing the film thickness and trying to etch the underlying wiring metal film, there is a part where the resist is completely etched before the etching of the metal film is completed. This is because it is difficult to normally form a wiring pattern having a predetermined dimension.

FIGS. 3 (a) to 3 (c) show an example of a process sectional view of a wiring forming process using a conventional hard mask.
In FIG. 3A, on the surface of the p-type silicon substrate 31,
0.8 μm thick BPSG (Bo
(Phospho-Silicate-Grass) film 32 is deposited, and an AlCu alloy film 33 having a thickness of 0.4 μm is formed on the surface thereof, and a TiN film 3 having a thickness of 0.05 μm is formed on the surface thereof.
4 and plasma CVD as a hard mask on its surface
A silicon oxide film 35 having a thickness of 0.2 μm is deposited by the method. The TiN film 34 is formed on the AlCu alloy film 33 which is a main component of the wiring, serves as an anti-reflection film in a photolithography process, and is necessarily required for fine wiring in order to suppress electromigration of the wiring. It is said that.

A resist mask 36 is patterned on the silicon oxide film 35, and the silicon oxide film 35 is patterned by dry etching using the resist mask 36 as an etching mask (FIG. 3B).

Next, using the resist mask 36 and the silicon oxide film 35 as an etching mask,
The laminated film of the lCu film 33 is sequentially etched (FIG.
(C)).

After that, the resist mask 36 is removed, and a metal wiring is completed. The remaining silicon oxide film 35 is used as it is as a part of the interlayer insulating film for insulating the upper and lower wiring layers.

[0008]

In the above steps,
As shown in FIG. 3B, when the silicon oxide film 35 as the hard mask is etched, the etching base is Ti.
N layer, CF used for etching silicon oxide film
_As can be seen from the fact that a fluorocarbon-based gas such as ₄ easily etches TiN, and that the TiF compound, which is an etching product, has a boiling point of 284 ° C., the vapor pressure is lower at the temperature inside the processing apparatus during dry etching. Low.

Therefore, the TiF compound 37 adheres to the inner wall of the processing chamber of the dry etching apparatus, and when the TiF compound 37 deposits and becomes thicker, it becomes particles 38 under plasma during etching and re-adheres to the wafer to generate pattern defects 39. Or The present invention provides a wiring structure and a wiring forming method for solving the problem of abnormalities occurring when using this hard mask.

[0010]

According to the wiring of the present invention which solves the above problems, a TiN film is formed on a surface layer of a conductive film mainly composed of aluminum or the like, and a Ti film is formed thereon.
Further, an electrical insulating film is formed on the Ti film.

Further, the method for manufacturing a wiring according to the present invention is characterized in that TiN
Forming a Ti film on the film, forming an insulating film on the Ti, forming a resist on the insulating film to form a wiring pattern, and forming a gas containing the insulating film with F using the resist as a mask. And a step of etching the Ti film and the TiN film using the resist and the insulating film as a mask.

Alternatively, a step of forming a Ti film on a TiN film, a step of forming an insulating film on Ti, a step of forming a resist on the insulating film and forming a wiring pattern, and a step of forming an insulating film using the resist as a mask And etching the Ti film and the TiN film using the insulating film as a mask after removing the resist.

Next, a semiconductor device according to the present invention is a semiconductor device in which a wiring film is formed on a semiconductor substrate, wherein a surface layer of the wiring film is a TiN film, and a Ti film is formed on the TiN film. Further, an electrical insulating film is formed on the Ti film.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, by forming a Ti film under an electric insulating film, Ti is converted into a fluorocarbon-based gas containing F for etching the electric insulating film as compared with TiN. Etching is difficult, so that a TiF compound having a low vapor pressure does not adhere to the inner wall of the chamber and cause particles to be generated. The preferred thickness of the Ti film under the electrically insulating film is 0.
003 to 0.03 μm.

In the method of manufacturing a wiring, the insulating film is
Etching with a gas containing Ti, a TiN film and T
It is preferable that the step of etching the i-film is performed in at least different processing chambers.

Further, if the step of etching the TiN film and the Ti film is performed with a gas mainly containing Cl and containing almost no F, TiF having a low vapor pressure can be used.
Rarely occurs.

(Embodiment 1) FIGS. 1A to 1C are sectional views showing the steps of an aluminum wiring forming process using a fine wiring forming method according to a first embodiment of the present invention. First, in FIG. 1A, a p-type silicon substrate 11 is formed.
0.8 thickness deposited by atmospheric pressure CVD on the surface of
A BPSG film 12 having a thickness of 0.4 μm is deposited, and
μm AlCu alloy film 13 and 0.05 μm thick Ti
An N film 14 and a Ti film 15 having a thickness of 0.03 μm were sequentially deposited to form a laminated structure for metal wiring. Next, a silicon oxide film 16 having a thickness of 0.2 μm was deposited by plasma CVD as a hard mask.

Next, a resist mask 17 is applied on the silicon oxide film 16 to a thickness of about 0.5 μm and patterned, and then the silicon oxide film 16 is patterned by dry etching using the resist mask 17 as an etching mask (FIG. 2). 1 (b)). The pattern width corresponding to the wiring at this time was about 0.25 μm. This silicon oxide film 16
For example, a parallel plate type RIE apparatus was used as an etching apparatus, and the etching conditions were, for example, as follows. (1) CHF ₃ : 10 sccm (2) CF ₄ : 20 sccm (3) Ar: 5 sccm (4) Pressure in the processing chamber: 5 Pa (5) RF power: 1000 W In the dry etching of the silicon oxide film 16 as a hard mask, The etching base was the Ti film 15. When the etching of the silicon oxide film 16 is removed, the underlying Ti film 15 is exposed and exposed to the above gas plasma. However, Ti is hardly etched by the fluorocarbon-based gas as compared with TiN, so that TiF is hardly etched. Does not occur. As an example, a silicon oxide film: TiN: T
The etching rate ratio of i in this gas is 100: 1
It is about 0: 1. Therefore, the TiF compound having a low vapor pressure adhered thickly to the inner wall of the chamber, and did not cause the generation of particles in the plasma and did not re-adhere to the wafer to generate pattern defects.

Next, the etching gas is changed using the resist mask 17 and the silicon oxide film 16 as an etching mask, and the Ti film 15, the TiN film 14 and the AlCu alloy film 1 are changed.
3 was etched (FIG. 1C). As an example of the etching conditions at this time, an inductive coupling type etching apparatus is used, and the supply amount of gas is BCl ₃ : 40 sc
cm, Cl ₂ : 140 sccm, CHF ₃ : 5 sccm
The chamber pressure was set to 10 mTorr. As described above, the etching gas is chlorine-based, and the F content is much lower than the etching gas for the silicon oxide film 16, so it can be said that TiF is hardly generated in this step. In some cases, the gas may not contain CHF ₃ .

The etching of the silicon oxide film 16 and T
An etching gas different from that used for the continuous etching of i, TiN, and AlCu is used. However, since TiF is hardly generated, there is no problem even if these are performed in the same processing chamber. Alternatively, these two steps can be performed in separate processing chambers or separate etching apparatuses, in which case the etching can be performed more safely. After that, the resist mask 1
7 is removed, and the metal wiring is completed. The remaining silicon oxide film 16 is used as it is as a part of the interlayer film.

(Embodiment 1) FIGS. 2A to 2D are sectional views showing the steps of an aluminum wiring forming process using a fine wiring forming method according to a second embodiment of the present invention. First, in FIG. 2A, the BPSG film 1 having a thickness of 0.8 μm is formed on the surface of the p-type silicon substrate 11 as in FIG.
2, a 0.4 μm-thick AlCu alloy film 13, a 0.05 μm-thick TiN film 14, and a 0.03 μm-thick Ti film 15 are sequentially deposited thereon. A laminated structure was formed. Next, a silicon oxide film 16 having a thickness of 0.2 μm was deposited by plasma CVD as a hard mask.

Next, a resist mask 17 is applied on the silicon oxide film 16 to a thickness of about 0.5 μm and patterned, and thereafter, the silicon oxide film 16 is patterned by dry etching using the resist mask 17 as an etching mask (FIG. 4). 2 (b)). The etching condition of the silicon oxide film 16 may be the same as the etching condition of FIG.

Next, the resist mask 17 is removed (FIG. 2).
(C)) Using the silicon oxide film 16 as an etching mask, the etching gas is changed to the gas used in the step of FIG. 1C of the first embodiment, and the Ti film 15, the TiN film 14, and the AlCu alloy film 13 are removed. The laminated film was etched (FIG. 2
(D)). Thereafter, the resist mask 17 was removed, and the metal wiring was completed. The remaining silicon oxide film 16 was used as it was as a part of the interlayer film.

As described above, the first embodiment is different from the first embodiment in that after the silicon oxide film 16 is patterned using the resist mask 17 as a mask, the resist mask 17 is removed and only the silicon oxide film 16 is used as an etching mask. The only difference is that the metal laminated film is etched, and there is no change in that TiF is hardly generated when the silicon oxide film 16 is etched.

As described above, according to the present invention, a thin Ti layer which is harder to be etched by a fluorocarbon-based gas than TiN is inserted between the TiN layer generally used as the uppermost layer of the wiring and the hard mask. By adopting the laminated wiring structure, the TiF compound having a low vapor pressure adheres to the inner wall of the chamber and may cause particles,
Wiring can be formed without re-adhering to the wafer and generating etching residue.

In the present invention, a thin film which is hardly etched by a fluorocarbon-based gas other than a Ti film underlying a silicon oxide film as a hard mask can be used. Examples of such a film include an Al and Al alloy film. However, when a Ti film is used, after forming a TiN film therebelow, it can be continuously formed in the same processing chamber using the same Ti film forming source, which can be said to be excellent in productivity.

[0027]

As described above, according to the present invention, a thin Ti layer which is harder to be etched by a fluorocarbon-based gas than TiN is provided between a TiN layer generally used as the uppermost layer of a wiring and a hard mask. By adopting the wiring layered structure, the TiF compound with low vapor pressure does not adhere to the inner wall of the chamber and cause particles, and does not cause re-adhesion to the wafer to generate etching residue. Enabled formation. TiN layer and Ti
Since the layers can be deposited in the same chamber, they are excellent in mass productivity, and their industrial value is great.

[Brief description of the drawings]

FIGS. 1A to 1C are process cross-sectional views of a wiring forming method according to a first embodiment of the present invention;

FIGS. 2A to 2D are process cross-sectional views of a wiring forming method according to a second embodiment of the present invention;

FIGS. 3A to 3C are process cross-sectional views of a conventional wiring forming method.

[Explanation of symbols]

 11, 31 p-type silicon substrate, 12, 32 BPSG film 13, 33 AlCu film 14, 34 TiN film 15 Ti film 16, 35 silicon oxide film 17, 36 resist mask 37 TiF compound 38 particle 39 pattern defect

Continued on the front page F term (reference) 4K057 DA02 DB06 DB08 DB11 DB15 DD05 DE04 DE06 DM02 DN01 5F004 AA14 AA15 BA20 CA01 DA00 DA01 DA02 DA03 DA04 DA11 DA15 DA16 DA17 DA18 DA19 DA20 DB08 DB09 DB12 DB16 EA06 EA22 EA28 H33HH33H33H QQ09 QQ13 QQ15 QQ28 RR04 SS15 XX00 XX21

Claims (6)

[Claims] A wiring film is formed on a semiconductor substrate, a surface layer of the wiring film is a TiN film, and a TiN film is formed on the TiN film.
A wiring, wherein a film is formed, and an electrical insulating film is further formed on the Ti film. A step of forming a Ti film on the TiN film; a step of forming an insulating film on the Ti film; a step of forming a resist on the insulating film to form a wiring pattern; A wiring forming method, comprising: a step of etching the insulating film with a gas containing F as a mask; and a step of etching the Ti film and the TiN film using the resist and the insulating film as a mask. A step of forming a Ti film on the TiN film; a step of forming an insulating film on the Ti; a step of forming a resist on the insulating film to form a wiring pattern; A method of etching the insulating film with a gas containing F as a mask, and a step of etching the Ti film and the TiN film using the insulating film as a mask after removing the resist. . 4. The wiring forming method according to claim 2, wherein the step of etching the insulating film with a gas containing F and the step of etching the TiN film and the Ti film are performed in at least different processing chambers. . 5. The wiring forming method according to claim 2, wherein the step of etching the TiN film and the Ti film is performed with a gas mainly containing Cl. 6. A semiconductor device having a wiring film formed on a semiconductor substrate, wherein a surface layer of the wiring film is a TiN film,
A semiconductor device comprising: a Ti film formed on the TiN film; and an electrical insulating film formed on the Ti film.