JP2000311885A - Semiconductor device having metal laminated wiring and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method of manufacturing of a semiconductor device with metal laminated wiring, which is modified so that irregularities in the wiring resistance of a metal laminated wiring is prevented from being generated, and the enhancement of the yield for the manufacture of the device can be obtained. SOLUTION: An upper layer metal film 5 containing tungsten (W) is dry- etched using a resist mask, whereby with the film 5 processed into a wiring shape, one part of the surface of a lower layer metal film 4 containing Ti is made to expose. The resist mask 7 is removed by ashing, using a plasma produced from O2 ashing gas doped with an F-containing gas. The film 4 is patterned into a wiring shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a method of manufacturing a semiconductor device having a metal stacked wiring, and more particularly, to a method of manufacturing a semiconductor device having a metal stacked wiring containing tungsten and titanium. .
The present invention also relates to a semiconductor device having a metal interconnect including tungsten and titanium.

[0002]

2. Description of the Related Art A conventional method for manufacturing a semiconductor device having a stacked wiring of a metal containing titanium such as tungsten and titanium nitride (TiN) under the tungsten will be described.

[0003] With reference to FIG. 7, on a substrate 1 having a SiO ₂ film 2 to the base, SiN film 6 / W film 5 / TiN film 4 /
A laminated wiring layer of the doped-poly-Si film 3 is formed. Using the resist pattern 7 as a mask, the uppermost silicon nitride film (SiN) 6 is dry-etched by reactive ion etching (RIE) using CF ₄ / O ₂ / Ar gas.

[0004] Then, referring to FIG. 8, using a resist mask 7, the tungsten 5 is dry-etched using SF ₆ / CF ₄ gas and inductively coupled plasma (ICP). At this time, a deposit 8 containing a reaction product at the time of dry etching is generated on the side wall portion. The deposit 8 contains a polymer containing tungsten.

Referring to FIGS. 8 and 9, the resist mask 7 is ashed and removed by down-flow plasma using O ₂ / N ₂ gas. At this time, the deposit 8 on the side wall remains without being removed during the ashing. After that, the remaining deposits 8 are removed by wet processing. For the wet treatment, a solution having a volume ratio of H ₂ SO ₄ / H ₂ O ₂ = 4: 1 and an NH ₄ OH / H ₂ O ₂ / H ₂ O = 1: 1: 5 solution are used.

At this time, referring to FIG. 9 and FIG. 10, H ₂ O ₂ contained in these solutions oxidizes and dissolves tungsten 5 so that tungsten 5 becomes approximately 500 °-
A 200 ° side etch occurs.

Referring to FIGS. 10 and 11, TiN film 4 / doped poly-Si is formed using silicon nitride 6 as a mask.
The film 3 is dry-etched by an electron cyclotron resonance (ECR) plasma using a Cl ₂ / O ₂ gas to form a wiring.

[0008]

A conventional method of manufacturing a semiconductor device having a metal laminated wiring has been configured as described above. However, this conventional method has a problem that the wiring of 0.3 μm or less, particularly 0.18 μm or less, has a large side etching ratio of the tungsten 5, the wiring resistance varies, and the yield decreases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has an improved metal laminated wiring so as to prevent a decrease in yield and to form a laminated wiring with good control. An object of the present invention is to provide a method for manufacturing a semiconductor device.

[0010] Another object of the present invention relates to a semiconductor device having a metal laminated wiring formed by such a method.

[0011]

According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor device having a metal laminated wiring, wherein first, a lower metal film containing Ti and an upper metal film containing W formed thereon. A substrate provided with is prepared. A resist mask having a wiring pattern is formed on the upper metal film. The upper metal film is dry-etched using the resist mask, thereby processing the upper metal film into a wiring shape and exposing a part of the surface of the lower metal film. Using the above resist mask, ashing is removed using plasma of an O ₂ ashing gas to which a gas containing F is added. The lower metal film is patterned into a wiring shape.

According to the present invention, the resist mask is made of F
Ashing is performed by using plasma of an O ₂ ashing gas to which a gas containing Ti is added, so that by selecting conditions, it is possible to prevent the generation of dust consisting of a compound of Ti and F on the surface of the lower metal film. Then, the deposit on the resist mask and the side wall can be removed.

In the method of manufacturing a semiconductor device having a metal laminated wiring according to the present invention, the concentration of the gas containing F may be such that dust composed of a compound of Ti and F is formed on the surface of the lower metal film. It is chosen not to accumulate.

According to the present invention, since no dust is deposited on the surface of the lower metal film, the poly-Si
No etching residue is generated.

According to a third aspect of the present invention, in the method of manufacturing a semiconductor device having a metal laminated wiring, the concentration of the gas containing F in the plasma of the O ₂ ashing gas is 0.25.
% Or less.

According to the present invention, since the concentration of the gas containing F is set to 0.25% or less, dust generated from the compound of Ti and F does not deposit on the surface of the lower metal film. .

According to a fourth aspect of the present invention, in the method of manufacturing a semiconductor device having a metal laminated wiring, the concentration of the gas containing F in the plasma of the O ₂ ashing gas is 0.1%.
As described above, Cl ₂ is added to the O ₂ ashing gas.

According to the present invention, since Cl ₂ is added to the O ₂ ashing gas, dust generation can be suppressed even if the concentration of the gas containing F increases.

According to a fifth aspect of the present invention, in the method of manufacturing a semiconductor device having a metal laminated wiring, the concentration of the gas containing F in the plasma of the O ₂ ashing gas is set to 3% or more, and the ashing of the resist mask is performed. Remove it,
Thereafter, a part of the exposed surface of the lower metal film is treated with diluted hydrofluoric acid.

According to the present invention, on the surface of the lower metal film,
Even if a compound of Ti and F is formed, it can be removed by dilute hydrofluoric acid treatment.

According to a sixth aspect of the present invention, in the method of manufacturing a semiconductor device having the metal laminated wiring, the upper metal film is formed of CF.
_x is performed using a gas containing _x, and when the upper metal film is over-etched,
The gas ratio of CF _x of the gas containing _x is reduced.

According to the present invention, when the over-etching of the metal film, so reducing the gas ratio of the CF _x in the gas containing the CF _x, when over-etching of the upper-layer metallic film, the surface of the lower metal film , And does not generate dust composed of a compound of Ti and F.

According to a seventh aspect of the present invention, in the method of manufacturing a semiconductor device having a metal laminated wiring, the upper metal film is formed of CF.
The dry etching is performed using a gas containing _x , and Cl ₂ is added when the upper metal film is over-etched.

According to the present invention, since Cl ₂ is added at the time of overetching the upper metal film, it is possible to prevent the generation of dust composed of a compound of Ti and F on the surface of the lower metal film.

A semiconductor device having a metal laminated wiring according to claim 8 includes a substrate. On the substrate, a lower metal wiring layer containing Ti and an upper metal wiring layer containing W formed thereon are provided. The side wall surface of the lower metal wiring layer is flush with the side wall surface of the upper metal wiring layer.

According to the present invention, since the side wall surface of the lower metal wiring layer is flush with the side wall surface of the upper metal wiring layer, the wiring resistance does not vary, and the yield is improved.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
The figure will be described.

Embodiment 1 Referring to FIG. 1, an SiN film 6 / tungsten (W) is formed on a substrate 1 having an SiO ₂ film 2 as a base, similarly to the prior art.
A laminated wiring layer of film 5 / TiN film 4 / doped-poly-Si film 3 is formed. Using the resist mask 7, the uppermost silicon nitride film (SiN film) 6 is dry-etched by reactive ion etching using CF ₄ / O ₂ / Ar gas.

Referring to FIGS. 1 and 2, a tungsten (W) film 5 is formed using a resist mask 7 in the same manner as in the prior art.
Using SF ₆ / CF ₄ gas and inductively coupled plasma,
Dry-etch. At this time, the deposit 8 is formed on the side wall.

Referring to FIGS. 2 and 3, gas containing F and O
_The resist mask 7 is ashed and removed by the plasma of the gas mixture with the resist mask 7. The gas containing F includes CF ₄ ,
CHF ₃ , CH ₂ F ₂ , C ₄ F ₈ and NF ₃ are used. The resist mask 7 is removed by ashing with O ₂ or a mixed gas of O ₂ and N ₂ , and at the same time, the deposit 8 on the side wall is also removed.

However, in this method, referring to FIG.
A dust 9 which is a compound of Ti and F is formed on the surface of the TiN film 4.
Accumulates.

FIG. 4 shows the relationship between the gas ratio and the amount of dust generated when CHF ₃ is added as an additive gas.
The relationship between the gas ratio and the amount of dust is shown). CHF to be added
It was found that as the gas ratio of ₃ increased, the amount of dust increased and the particle size also increased. When the underlying TiN film 4 and the doped poly-Si film 3 are etched while leaving the dust particles 9, the dust particles 9 serve as a mask to form the poly-Si film.
An etching residue of the Si film 3 is generated, and the yield decreases. The dust 9 can be suppressed by setting the gas ratio of CHF ₃ to about 3% or less. Using the process conditions shown below, using down-flow plasma,
It is preferable to perform an ashing process.

Gas: O ₂ / CHF ₃ = 2000 sccm /
2 sccm to 5 sccm pressure = 150 Pa μ wave power = 1
Even if the 000 WCHF ₃ is 2 sccm (0.1%), the dust particles 9 can be removed simultaneously with the resist mask 7. By adding a gas containing a small amount of F, dust generation can be suppressed, and the resist mask 7 and the deposit 8 can be removed. Here, even if N ₂ is added during ashing, the deposit 8 on the side wall is still removed.

At the same time, the relationship between the gas ratio and the amount of dust when a small amount of Cl ₂ (10%) is added is shown by white circles in FIG.
By adding a small amount of Cl ₂ to the ashing gas, even if the addition amount of CHF ₃ was increased, it was possible to suppress an increase in dust generation. This is the Cl _2, Ti is Ti
This is because etching is performed as Cl _x (x = 2 to 4). The underlying TiN layer 4 is also etched, but in this range, the etching resist of the resist mask 7 is sufficiently large (> 100 times), so that sufficient control can be performed.

According to these methods, a pattern of a desired shape of tungsten film 5 can be obtained with reference to FIG.

Referring to FIGS. 5 and 6, thereafter, as in the conventional case, TiN film 4 /
The doped-poly-Si film 3 is dry-etched by ECR plasma using Cl ₂ / O ₂ gas to form a semiconductor device having a metal laminated wiring. In the semiconductor device obtained by this method, the side wall surface of the TiN film 4 is flush with the side wall surface of the W film 5.

Since the side wall surface of the W film 5 and the side wall surface of the TiN film 4 are flush, unlike the conventional one (FIG. 10),
There is no variation in wiring resistance. As a result, the yield is improved.

Embodiment 2 Embodiment 1 relates to a technique for suppressing dust generation and improving the yield. In Embodiment 2, however, by changing the wet processing method after the ashing processing, It relates to removing the generated dust.

The conventionally used O_Two/ N_TwoPlas with gas
In this case, the deposits on the side wall cannot be removed, and then H_Two
SO_Four/ H_TwoO_TwoAnd NH_FourOH / H_TwoO_Two/ H_TwoO solution
Wet treatment was required. However, CF_Four, C
HF_Three, CH_TwoF_Two, C_FourF₈, NF _ThreeGas containing F
By adding 0.1% or more, sediment can be removed.
Is possible, and H used in the prior art is used._TwoSO_Four/
H_TwoO_TwoAnd NH_FourOH / H_TwoO _Two/ H_TwoO solution
This eliminates the need for a port process.

3% or more of CF ₄ , CHF ₃ , CH ₂ F ₂ , C
Even if a gas containing F such as ₄ F ₈ or NF ₃ is used, or a compound of Ti and F is formed on the TiN surface, it can be removed by dilute hydrofluoric acid treatment.

The chemical used for the treatment has a HF concentration of 0.01 to 4% diluted with pure water. The processing temperature is room temperature (23 ° C.).

By performing the diluted hydrofluoric acid treatment, Ti in the compound is etched by the diluted hydrofluoric acid, and at the same time, the underlying TiN film is also etched and lifted off. At this time, since the TiN film is isotropically etched by dilute hydrofluoric acid, it is side-etched, but the amount is 40 ° or less, which is not a problem. In addition, the oxide film on the surface of the TiN film, which is generated at the time of ashing by the diluted hydrofluoric acid treatment, is removed by the diluted hydrofluoric acid.
Dry etching of the iN film 4 / doped-poly-Si film 3 can be performed with good control. By processing the silicon nitride film and the tungsten wiring by the above-described method, it is possible to obtain a clean surface having no deposit on the side wall and no dust generation on the surface (FIG. 5). Thereafter, the TiN film 4 / doped poly-Si film 3 is dry-etched by ECR plasma using HBr / O ₂ gas. The etching conditions are as follows.

Gas: HBr / O ₂ = 20-200 scc
m / 2 to 20 sccm Pressure: 2.0 to 5.0 Pa Microwave power: 400 to 1500 W Coil current 1: 14 A Coil current 2: 14 A Coil current 3: 3 A Lower electrode power: 20 to 60 W Selectivity with underlying SiO ₂ Under a high etching condition (> 30), the TiN film 4 / doped-poly-Si film 3 is selectively etched to form a desired laminated metal wiring (FIG. 6).

Embodiment 3 Dust generated by a compound of Ti and F is generated by the tungsten wiring film 5.
Also occurs during dry etching. During over-etching at the time of etching tungsten, the underlying TiN film 4
Is etched, and CF ₄ contained in the etching gas is removed.
This is because such a compound is formed. Tungsten etching conditions when ICP plasma is used are shown below.

Gas: SF ₆ / CF ₄ = 30 to 500 scc
m / 5 to 100 sccm Pressure: 2 to 50 mTorr Upper coil power: 400 to 2000 W Lower electrode power: 20 to 150 W To control the etching shape, C was added as an additive gas.
In addition to _{F 4, CHF 3, CH 2} F 2, NF 3 is also used. At this time, dust is not necessarily generated when the gas ratio of CF ₄ is 4% or more. This is because unlike a downflow plasma, a polymer is hardly formed by colliding ions.

When the RF power applied to the electrode held by the wafer being etched is reduced, dust is likely to occur,
Assuming that the flow ratio of CF ₄ is 50%, dust is generated when the RF power of the lower power becomes 100 W or less, and the flow ratio of CF ₄ becomes 20%.
%, When the RF power of the lower electrode becomes 50 W or less, dust is easily generated. Increasing the RF power has disadvantages such as a decrease in the resist selectivity and a tendency to form a tapered shape.
Add 00 sccm of Cl ₂ .

As the amount of Cl ₂ added increases, the shaving amount of the underlying TiN film increases. Therefore, the amount of Cl ₂ added is set depending on the thickness of the underlying layer. SF with Cl ₂ added
By etching the tungsten film with ₆ / CF ₄ / Cl ₂ , dust generation can be suppressed even if the RF power is reduced, and the control range of the etching process can be widened.

Further, since dust is generated during the over-etching of tungsten, it may be limited to the over-etching. By monitoring the F emission consumed during the etching, the end point of the tungsten etching can be determined from the variation of the emission, and the etching gas can be changed only by over-etching.

Therefore, at least at the time of over-etching of tungsten etching, the gas ratio of CF ₄ is reduced. Alternatively, at the time of over-etching of tungsten, Cl ₂ is added to prevent generation of a compound of Ti and F, and the shape shown in FIG. 2 can be obtained. Thereafter, through the steps of FIGS. 3, 5, and 6, a semiconductor device having a metal laminated wiring without variation in wiring resistance can be obtained.

The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0051]

According to the method of manufacturing a semiconductor device having the metal laminated wiring according to the first aspect, the resist mask is formed by using F
Using a plasma of O ₂ ashing gas added a gas containing, since the ashing, by selecting the conditions, the surface of the lower metal film, without depositing the dust composed of compounds of Ti and F, There is an effect that the deposit on the resist mask and the side wall can be removed.

In the method of manufacturing a semiconductor device having the metal laminated wiring according to the second aspect, since dust is not deposited on the surface of the lower metal film, no etching residue of poly-Si is generated in a later step.

In the method for manufacturing a semiconductor device having the metal laminated wiring according to the third aspect, the concentration of the gas containing F is set to 0.25% or less, so that Ti and No dust composed of the compound of F accumulates.

According to a fourth aspect of the present invention, in the method of manufacturing a semiconductor device having a metal laminated wiring, the O ₂ ashing gas may contain C
Since l ₂ is added, dust generation can be suppressed even when the concentration of the gas containing F increases.

According to a fifth aspect of the present invention, in the method of manufacturing a semiconductor device having the metal laminated wiring, the surface of the lower metal film is
Even if a compound of i and F is formed, it can be removed by dilute hydrofluoric acid treatment.

[0056] In the method of manufacturing a semiconductor device having a metal laminated wiring according to claim 6, when over-etching of the metal film, so reducing the gas ratio of CF _x in a gas containing CF, when over-etching of the upper-layer metallic film In addition, dust generated from a compound of Ti and F is not generated on the surface of the lower metal film.

In the method of manufacturing a semiconductor device having a metal laminated wiring according to claim 7, Cl ₂ is added at the time of overetching the upper metal film, so that the surface of the lower metal film is made of a compound of Ti and F. Generation of dust can be prevented.

According to the semiconductor device having the metal laminated wiring according to the eighth aspect, the side wall surface of the lower metal wiring layer is flush with the side wall surface of the upper metal wiring layer. Thus, the yield is improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a semiconductor device in a first step in a sequence of a method of manufacturing a semiconductor device according to a first embodiment.

FIG. 2 is a cross-sectional view of the semiconductor device in a second step in the order of the method of manufacturing the semiconductor device according to the first embodiment;

FIG. 3 is a cross-sectional view of the semiconductor device in a third step in the order of the method of manufacturing the semiconductor device according to the first embodiment;

FIG. 4 is a diagram showing a relationship between a gas ratio of O ₂ / CHF ₃ and foreign matter.

FIG. 5 is a sectional view of the semiconductor device in a fourth step in the order of the method of manufacturing the semiconductor device according to the first embodiment;

FIG. 6 is a sectional view of the semiconductor device in a fifth step in the sequence of the method for manufacturing the semiconductor device according to the first embodiment;

FIG. 7 is a cross-sectional view of a semiconductor device in a first step in a sequence of a conventional method of manufacturing a semiconductor device.

FIG. 8 is a cross-sectional view of a semiconductor device in a second step in the sequence of the conventional method of manufacturing a semiconductor device.

FIG. 9 is a cross-sectional view of a semiconductor device in a third step in the sequence of the conventional method of manufacturing a semiconductor device.

FIG. 10 shows a fourth example of the sequence of the conventional method for manufacturing a semiconductor device.
13 is a cross-sectional view of the semiconductor device in a step of FIG.

FIG. 11 shows a fifth example of the sequence of the conventional method of manufacturing a semiconductor device.
13 is a cross-sectional view of the semiconductor device in a step of FIG.

[Explanation of symbols]

1 substrate, 2 SiO ₂ film, 3 doped poly-Si
Film, 4 TiN film, 5 W film, 6 SiN film.

Continued on the front page F-term (reference) 4M104 BB01 BB18 BB30 DD65 EE17 FF13 FF16 HH20 5F004 AA13 BA14 BA20 BB14 BD01 DA00 DA01 DA04 DA15 DA16 DA17 DA18 DA23 DA25 DA26 DA30 DB03 DB07 DB08 DB10 DB26 EA07 EA13 H03 MM03 EB03 5H04 MM13 QQ13 QQ15 QQ19 RR04 RR06 XX00 XX21

Claims (8)

[Claims] A step of preparing a substrate provided with a lower metal film containing Ti and an upper metal film containing W formed thereon; and having a wiring-shaped pattern on the upper metal film. Forming a resist mask, using the resist mask, dry-etching the upper metal film, thereby processing the upper metal film into a wiring shape and exposing a part of the surface of the lower metal film. Performing ashing, using a plasma of an O ₂ ashing gas to which a gas containing F is added, and a step of patterning the lower metal film into a wiring shape. A method for manufacturing a semiconductor device having a metal laminated wiring. 2. The metal according to claim 1, wherein the concentration of the gas containing F is selected so that dust formed of a compound of Ti and F does not deposit on the surface of the lower metal film. A method for manufacturing a semiconductor device having stacked wiring. 3. The method according to claim 1, wherein the concentration of the gas containing F in the plasma of the O ₂ ashing gas is set to 0.25% or less. . 4. The concentration of the gas containing F in the plasma of the O ₂ ashing gas is set to 0.1% or more, and Cl ₂ is added to the O ₂ ashing gas. Item 2. A method for manufacturing a semiconductor device having the metal laminated wiring according to Item 1. 5. The method of claim ₂ , wherein the concentration of the gas containing F in the plasma of the O ₂ ashing gas is set to 3% or more, and the ashing of the resist mask is removed. 2. The method according to claim 1, wherein the portion is treated with diluted hydrofluoric acid. The method according to claim 6, wherein the upper-layer metallic film, using a gas containing CF _x, perform the dry etching, when over-etching of the upper layer metal film, lowering the gas ratio of the CF _x gas containing the CF _x A method of manufacturing a semiconductor device having a metal laminated wiring according to claim 1. 7. The metal-laminated wiring according to claim 1, wherein the upper metal film is subjected to the dry etching using a gas containing CF _x , and Cl ₂ is added when the upper metal film is over-etched. A method for manufacturing a semiconductor device having: 8. A substrate, comprising: a lower metal wiring layer including Ti, provided on the substrate; and an upper metal wiring layer including W formed thereon; A semiconductor device having a metal laminated wiring, wherein a side wall surface is flush with a side wall surface of the upper metal wiring layer.