JPH05206081A - Dry etching method - Google Patents

Abstract

PURPOSE:To suppress the loading effect and improve the selectiveness for a Ti barrier metal when a W layer (Blk-W layer) formed by the blanket CVD method is etched back. CONSTITUTION:In the etch back process of a Blk-W layer 5, Br gas is used at least in the vicinity of the interface with a TiN barrier metal 4 and a wafer is heated. The reaction product WBr6 of Br and W has relatively low vapor pressure and the reacting product TiBr4 of Br and Ti has relatively high vapor pressure. Namely, the etching speed is decreased and the loading effect is suppressed compared with the case that F gas is used for etch back and higher selection ratio is allowed compared with the case that Cl gas is used. For example, when HBr/SF6 mixed gas is used for just etching and HBr is used for over etching, a connecting hole 3a is flatly buried by the high-speed etch back.

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 applied in the field of manufacturing semiconductor devices, and particularly titanium (Ti) for etching back a refractory metal layer formed by a so-called blanket CVD method.
The present invention relates to a method of suppressing a loading effect while ensuring high selectivity with respect to a system barrier metal.

[0002]

2. Description of the Related Art As the integration and performance of semiconductor devices have increased as seen in VLSI, ULSI and the like in recent years, the proportion of the wiring portion on the device chip tends to increase. Multilayer wiring is now an indispensable technology in order to prevent a large increase in chip area. Conventionally, as a wiring forming method, a metal thin film made of aluminum or the like has been widely formed by a sputtering method. However, under the situation where the multilayer wiring progresses as described above, and as a result, the surface step of the substrate and the aspect ratio of the connection hole increase, due to the lack of step coverage in the sputtering method, the upper wiring and the semiconductor substrate A poor connection between the wiring and the wiring has already become a serious problem.

Therefore, in recent years, refractory metals such as tungsten (W), molybdenum (Mo) and tantalum (Ta) or metals such as aluminum (Al) and copper (Cu) are selectively grown in the connection holes. Has proposed a technique for filling a connection hole having a high aspect ratio. A typical example of such a selective growth method is a selective CVD method in which a gas such as a metal fluoride or an organic metal compound is reduced by a lower wiring material to deposit a metal.

However, although the selective CVD method has obtained quite good results at the research level, the selectivity gradually deteriorates, or the controllability at the time of etching back removal of an overgrown portion, which is commonly called a nail head, is poor. Due to such difficulties, the current situation is that there is no prospect of introduction to mass production, contrary to the initial expectations. In place of this selective CVD, the blanket CVD method has attracted attention again. This is a technique for depositing a metal or an alloy on the entire surface of the base body. For example, the process of forming the refractory metal layer of W or the like by covering the entire surface of the insulating film in which the connection hole is opened and filling the connection hole is not performed. This is a typical example.

By the way, when the refractory metal layer is embedded in the connection hole and used as a so-called plug, it is necessary to etch back the refractory metal layer.
In this etch-back process, it is usual to perform over-etching of about 5 to 10% in consideration of the uniformity of processing on the wafer surface. However, even on the same wafer surface, the etching rate is higher in the portion close to the region where the plasma density in the etching apparatus is relatively high, so that the area to be etched is not rapidly reduced. It occurs early. Then, there is a problem in that radicals that have lost a binding partner (that is, a refractory metal) and are relatively excessive are concentrated in the connection hole, and the barrier metal and the refractory metal layer embedded therein are largely eroded. This problem will be described with reference to FIG.

For example, as shown in FIG. 2A, an interlayer insulating film 13 is formed on a semiconductor substrate 11 in which an impurity diffusion region 12 is formed in advance, and the interlayer insulating film 13 faces the impurity diffusion region 12. Consider a wafer in which a connection hole 13a is opened, a TiN barrier metal 14 is formed on the entire surface by a sputtering method, and a Blk-W layer 15 is formed so as to fill the connection hole 13a by a blanket CVD method.

Here, the above-mentioned Blk is produced by using a fluorine-based gas.
When the -W layer 15 is etched back, F ^* becomes excessive at an early stage when the surface of the TiN barrier metal 14 is exposed near the high plasma density region. This is the connection hole 13a
This concentrates on the surface of the Blk-W layer 15 buried inside, and forms a large eroded portion 16 as shown in FIG. 2B during overetching.
Moreover, since the selectivity to the TiN barrier metal 14 is insufficient, the rough surface morphology of the Blk-W layer 15 is transferred to the surface of the TiN barrier metal 14.

Then, when the etching gas is switched to chlorine gas or the like and the barrier metal 14 is etched back,
This time, radicals become excessive when the surface of the interlayer insulating film 13 is exposed, and these radicals are concentrated on a slight cross section of the barrier metal 14 embedded in the connection hole 13. As a result, a large eroded portion 17 is formed as shown in FIG. Further, the surface morphology of the TiN barrier metal 14 is also transferred to the interlayer insulating film 13, and there is a great possibility that the adhesion and reliability of the upper layer wiring formed in a later step are adversely affected.

As described above, the phenomenon that radicals become relatively excessive as the area of the material layer to be etched decreases and the etching rate rapidly increases is called a loading effect, and the blanket CVD method is practically used. It is the cause that is hindering the realization. In the field of semiconductor device manufacturing in the future, single wafer type plasma etching in which high-speed etching is performed using high-density plasma so that the diameter of the wafer will increase with the increase in the size of device chips and that throughput will not decrease. Since the device is expected to become the mainstream, it is considered that the loading effect becomes more remarkable. Therefore, an urgent solution is desired.

As a means for eliminating such a loading effect, one of the known techniques applied to commercially available devices and the like is to divide the etch back into two steps, a just etching step and an over etching step, and in the latter, lowers the etching rate. There is technology. When the Blk-W layer is etched back by this technique, for example, high-speed etching is performed using F ^* as the main etching species in the just etching step, that is, the step immediately before the underlying layer is substantially exposed, and Cl ₂ is used in the overetching step. /
Slow etching is performed using O ₂ mixed gas. here,
In the overetching process, not only Cl ₂ but O
_The etching gas containing ₂ is used because WCl ₆ having a low vapor pressure (boiling point 34
6.7 ° C) alone, but with a slightly higher vapor pressure than WCl ₄ O (boiling point 227.4 ° C), WCl 4
_{This is because} the oxychloride such as ₂ O ₂ (boiling point 266 ° C.) is also generated so that the etching proceeds smoothly at a low speed.

[0011]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The suppression of the loading effect on the W layer was tentatively achieved by the above-mentioned technique of removing the Blk-W layer in the form of oxychloride in the overetching step. However, this process raises the following new issues.

Although Cl ₂ is contained in the above etching gas, TiCl ₄ which is a typical reaction product of Cl ₂ and titanium has a low boiling point of 136.4 ° C. and has a tungsten oxychloride. It has a much higher vapor pressure. That is, once the Ti-based barrier metal is exposed in the process of etching back the Blk-W layer, the Ti-based barrier metal is etched faster than the Blk-W layer.

Therefore, as shown in FIG. 3, even if the loading effect can be prevented for the Blk-W layer 15, the formation of the contact portion 17 is prevented for the TiN barrier metal 14 inside the connection hole 13a. Difficult to do. Therefore, the present invention provides a method capable of ensuring high selectivity with respect to a Ti-based barrier metal and effectively suppressing a loading effect when etching back a refractory metal layer formed by a blanket CVD method. With the goal.

[0014]

The dry etching method of the present invention is proposed to achieve the above-mentioned object. That is, the dry etching method according to the first invention of the present application is configured by laminating a Ti-based barrier metal and a refractory metal layer in this order, and is formed in such a manner that the connection hole opened in the interlayer insulating film is buried substantially flat. A method of etching back the laminated wiring layer formed by: etching the refractory metal layer using an etching gas containing at least a bromine compound; and etching back the Ti barrier metal. And a second step.

In the dry etching method according to the second invention of the present application, in the first step, the etching
The gas further contains a fluorine-based compound.

The dry etching method according to the third invention of the present application is also a method of etching back the laminated wiring layer, which comprises etching at least a fluorine compound.
A first step of etching back the refractory metal layer with a gas until substantially immediately before the Ti-based barrier metal is exposed; and an etching gas containing at least a bromine-based compound while heating the substrate to be etched. A second step of overetching the refractory metal layer;
and a third step of etching back the i-type barrier metal.

Further, the dry etching method according to the fourth invention of the present application is characterized in that, in the second step of the third invention, the etching gas further contains a fluorine compound.

[0018]

In the etching back of the refractory metal layer, in order to suppress the loading effect and improve the selectivity with respect to the Ti-based barrier metal as compared with the conventional case, it is not as high as fluoride when reacted with the refractory metal. Is an etching species that gives a reaction product having a vapor pressure sufficiently high for volatilization and removal under reduced pressure, and further a reaction product having a vapor pressure sufficiently lower than titanium chloride when reacted with a Ti-based barrier metal. is necessary. As the etching species, the present inventor has focused on bromine (Br).

For example, when W is considered as a typical refractory metal, the boiling point of WBr ₆ , which is a reaction product of Br and W, is 232 ° C., and WCl ₆ (boiling point 346.7 ° C.)
100 ° C lower than that of the above-mentioned WCl ₄ O (boiling point 22
(7.4 ° C). That is, if the substrate to be etched (wafer) is heated to such an extent that the desorption of the reaction product is promoted, the refractory metal layer can be sufficiently etched back even if only Br is used as the etching species.

On the other hand, T which is a reaction product of Br and Ti
The boiling point of iBr ₄ is 230 ° C.
Nearly 100 ° C higher than ₄ (136.4 ° C). That is, when the Ti-based barrier metal is exposed, a reaction product having a low vapor pressure is formed on the surface of the Ti-based barrier metal, and the etching rate is reduced to ensure high selectivity. As described above, when Br is used as the etching species, the refractory metal layer can be etched back at the same rate as in the case of using the conventional Cl ₂ / O ₂ mixed gas system, and the underlying Ti-based barrier metal can be removed. Higher selectivity can be achieved.

If such high selectivity is achieved for the Ti-based barrier metal, it is possible to reduce the amount of overetching of the Ti-based barrier metal. This is because even if the refractory metal layer is thoroughly removed on the exposed surface of the Ti-based barrier metal, the rough surface morphology of the refractory metal layer is not transferred to the Ti-based barrier metal. This makes it easy to prevent the Ti-based barrier metal from invading the inside of the connection hole.

Here, the Br-based compound for supplying Br is used over the entire etch-back process of the refractory metal layer, or over-etching in which the selectivity with respect to the underlying Ti-based barrier metal is important. It does not matter whether it is used only in the process. Further, since the vapor pressure of bromide may be low depending on the type of refractory metal, a fluorine-based compound may be used to speed up the etching. This fluorine-based compound may be used throughout the etch-back process of the refractory metal layer, or may be used only in the just etching process.

Considering the above conditions, the following four processes (a) to (d) can be considered. (A) The entire etch back is performed using only the bromine-based compound while heating the wafer. (B) The entire etch back is performed using a mixed system of a bromine compound and a fluorine compound while heating the wafer.

(C) Just etching is performed using substantially only a fluorine-based compound, and overetching is performed using only a bromine-based compound while heating the wafer. (D) Just etching uses substantially only a fluorine compound, and over etching is performed using a mixed system of a bromine compound and a fluorine compound while heating the wafer.

Here, the reason for partially saying "substantially" is that it is assumed that an inert gas such as Ar or He that does not supply the main etching species is added. These processes (a) to (d) correspond to the first to fourth inventions of the present application in this order. The etching rate corresponds to the first invention [(a). ]
From the fourth invention [corresponding to (d). ] Becomes faster in that order.

As a technique related to the present invention, the applicant of the present invention has previously described in Japanese Patent Application No. 3-29658 that a sulfur dioxide gas is rich in the just etching process and HBr gas is used in the over etching process. We propose a technology to etch back the refractory metal layer under rich conditions. This is near the end of etch back, that is, SiO
_The purpose is to lower the vapor pressure of the etching reaction product near the interface with the _two- layer insulating film, thereby lowering the etching rate and improving the controllability.

On the other hand, the present invention assumes that the refractory metal layer is used as a laminated system with the Ti-based barrier metal, and achieves high selectivity for the Ti-based barrier metal while suppressing the loading effect. It is an object. Therefore, the purpose and structure are different from those of the prior application.

[0028]

EXAMPLES Specific examples of the present invention will be described below.

Example 1 This example is an example in which the first invention of the present application is applied and a Blk-W layer laminated on a TiN barrier metal is etched back by using HBr while heating a wafer. This process will be described with reference to FIG. The wafer used as the etching sample in this example is shown in FIG.
As shown in (a), an SiO ₂ interlayer insulating film 3 is formed on a silicon substrate 1 in which an impurity diffusion region 2 is formed in advance, and a contact hole 3a is formed so as to face the impurity diffusion region 2. A thin TiN barrier metal 4 is formed on the entire surface of the substrate so as not to fill the contact hole 3a.
And a Blk-W layer 5 is formed by a blanket CVD method so as to fill the contact hole 3a and cover the entire surface. Here, in the blanket CVD method, for example, the WF ₆ flow rate is 25 SCCM, the SiH ₄ flow rate is 10 SCCM, the gas pressure is 1.06 × 10 ⁴ Pa (80 Torr), and the wafer temperature is 4
After performing nuclei growth for 20 seconds at 75 ° C., the gas supply conditions are WF ₆ flow rate 60 SCCM, H ₂ flow rate 360 SCC.
W was deposited while changing to M. The Blk-W layer 5 thus formed had a rough surface morphology as schematically shown.

Next, the above wafer was set in an RF bias application type magnetic field microwave plasma etching apparatus, and as an example, the Blk-W layer 5 was etched back under the following conditions. HBr flow rate 50 SCCM Gas pressure 1.3 Pa (10 mTorr) Microwave power 850 W (2.45 GHz) RF bias power 50 W (2 MHz) Wafer temperature 200 ° C. In this process, HBr reacts with the Blk-W layer 5 to cause etching reaction. Although WBr ₆ was mainly produced as a product, since the wafer was heated to 200 ° C. under reduced pressure, this WBr ₆ had a sufficient vapor pressure and was rapidly desorbed.

FIG. 1B shows an intermediate state of the etch back. At this stage, the underlying TiN barrier metal 4 may already be exposed in another region on the wafer (not shown). Etching back was further continued, and was completed when the TiN barrier metal 4 was exposed over the entire area of the wafer as shown in FIG. 1 (c). On the exposed surface of the TiN barrier metal 4, mainly T
iBr ₄ is formed. Since TiBr ₄ has a boiling point extremely close to that of WBr ₆ , it is considered that both have the same vapor pressure in the etching reaction system. Therefore, unlike the conventional method using the Cl ₂ / O ₂ mixed gas system, the TiN barrier metal 4 is not etched earlier than the Blk-W layer 5 at this stage. At this stage, the selection ratio with respect to the TiN barrier metal 4 becomes about 5, and even if the Blk-W layer 5 is sufficiently removed on the exposed surface of the TiN barrier metal 4, the Blk-W layer 5 is not immersed in the contact hole 3a. It wasn't touched. Moreover, the rough surface morphology of the Blk-W layer 5 was not transferred to the TiN barrier metal 4.

Further, the above-mentioned wafer was transferred to another chamber, and as an example, the TiN barrier metal 4 was etched back under the following conditions. Cl ₂ flow rate 40 SCCM O ₂ flow rate 10 SCCM Gas pressure 1.3 Pa (10 mTorr) Microwave power 850 W (2.45 GHz) RF bias power 100 W (2 MHz) Wafer temperature 200 ° C. In this etch back, the SiO ₂ interlayer insulating film 3 is exposed. It stopped when it did. As a result, as shown in FIG. 1D, the TiN barrier metal 4 is formed in the contact hole 3a.
And the Blk-W layer 5 were plugged flat. Moreover, since the surface morphology of the TiN barrier metal 4 before the start of etch back was good, the overetching amount was small, and the TiN barrier metal 4 was not touched in the contact hole 3a. Of course, the surface morphology of the underlying SiO ₂ interlayer insulating film 3 was also good.

Example 2 In this example, the second invention of the present application is applied, and a Blk-W layer laminated on a TiN barrier metal is etched back using a HBr / SF ₆ mixed gas while heating a wafer. It is an example. The wafer used as the etching sample is the same as that shown in FIG. This wafer was set in a magnetic field microwave plasma etching apparatus, and as an example, the Blk-W layer 5 was etched back under the following conditions.

HBr flow rate 45 SCCM SF ₆ flow rate 5 SCCM Gas pressure 1.3 Pa (10 mTorr) Microwave power 850 W (2.45 GHz) RF bias power 50 W (2 MHz) Wafer temperature 200 ° C. In this process, the mechanism described in Example 1 was used. In addition to SF ₆
The Blk-W layer 5 becomes W by the contribution of F ^* generated by dissociation from
It is also removed in the form of F ₆ . Therefore, the etching rate was higher than that in Example 1. But SF
_Since the amount of ₆ added was small, the loading effect could not be realized. The mechanism by which high selectivity is achieved on the exposed surface of the TiN barrier metal 4 is as described above in the first embodiment.

Example 3 In this example, the third invention of the present application is applied, and SF ₆ / Ar mixed gas is used in the just etching process of the Blk-W layer.
This is an example in which HBr is used in the overetching process. First, the wafer shown in FIG. 1A was set in a magnetic field microwave plasma etching apparatus, and as an example, the Blk-W layer 5 was just-etched under the following conditions.

SF ₆ flow rate 50 SCCM Ar flow rate 50 SCCM Gas pressure 1.3 Pa (10 mTorr) Microwave power 850 W (2.45 GHz) RF bias power 100 W (2 MHz) Wafer temperature 200 ° C. In this process, F generated by dissociation from SF ₆ is generated. Due to the contribution of ^*, the Blk-W layer 5 was mainly removed in the form of WF ₆ , and since this radical reaction was assisted by the incident energy of ions such as SF _x ⁺ , Ar ⁺ , high-speed etching proceeded. This just etching is shown in Figure 1.
As shown in (b), the process was completed when the remaining amount of the Blk-W layer 5 on the TiN barrier metal 4 became small.

Next, the Blk-W layer 5 was overetched by switching the etchback conditions to those described in Example 1 as an example. In this overetching process, HBr is used alone, so the etching rate is lower than in the just etching process, and the loading effect is suppressed. Further, the selectivity for the TiN barrier metal 4 was improved.

In the present embodiment, the etching rate was greatly increased in the just etching step, which occupies most of the time required for the etch-back process, so that the time required for the entire process was greatly shortened as compared with the first embodiment. ..

Example 4 This example is also an application example of the third invention of the present application, similar to Example 3, and in the just etching step of the Blk-W layer, S is applied.
F ₆ / Ar mixed gas, S _{2 in the} over etching process
Br ₂ was used. First, the wafer shown in FIG. 1A was set in a magnetic field microwave plasma etching apparatus, and the Blk-W layer 5 was just-etched under the conditions described in Example 3. This process proceeded at high speed as described above.

Next, the Blk-W layer 5 was overetched by switching the etchback conditions to the following conditions as an example. S ₂ Br ₂ flow rate 50 SCCM Gas pressure 1.3 Pa (10 mTorr) Microwave power 850 W (2.45 GHz) RF bias power 50 W (2 MHz) Wafer temperature 140 ° C. Here, the above S ₂ Br ₂ is characterized by the applicant. Wishhei 3-2
No. 10516 specification, silicon-based material layer, Al
It is a compound proposed as an etching gas for the system material layer, which can generate Br ^* under discharge dissociation conditions while releasing free S. This S is deposited on the wafer if the wafer is cooled to approximately the room temperature range, but since the wafer is heated in this embodiment, such deposition does not occur. However, when the surface of the TiN barrier metal 4 is exposed, N supplied from the TiN bonds with the above S, and a sulfur nitride compound such as polythiazyl (SN) _x is formed. The above wafer temperature is close to the upper limit of the temperature at which the sulfur nitride-based compound can exist stably, but in this embodiment, the selectivity can be expected to be improved by the sulfur nitride-based compound in addition to TiBr ₄ . In this embodiment, the selection ratio is about 20.
Improved.

The sulfur nitride-based compound remaining on the wafer can be easily sublimated or decomposed by heating the wafer to about 150 ° C. or higher after completion of the etch back, and cause any particle contamination on the wafer. It wasn't something.

Example 5 In this example, the fourth invention of the present application is applied, and SF ₆ / Ar mixed gas is used in the just etching step of the Blk-W layer.
In the over-etching process, this is an example in which S ₂ Br ₂ / S ₂ F ₂ mixed gas is used. First, the wafer shown in FIG. 1A was set in a magnetic field microwave plasma etching apparatus, and the Blk-W layer 5 was just-etched under the conditions described in Example 3. This process proceeded at high speed as described above.

Next, the Blk-W layer 5 was over-etched by changing the etch-back conditions to the following conditions as an example. S ₂ Br ₂ flow rate 40 SCCM S ₂ F ₂ flow rate 10 SCCM Gas pressure 1.3 Pa (10 mTorr) Microwave power 850 W (2.45 GHz) RF bias power 50 W (2 MHz) Wafer temperature 100 ° C. where S ₂ F ₂ is The applicant of the present application is also Japanese Patent Application No. 3
-210516 specification, etc., a silicon-based material layer,
It is a compound proposed as an etching gas for an Al-based material layer, which can generate F ^* under discharge dissociation conditions while releasing free S. In this embodiment, F ^* also participates in the over-etching process, so that the etch-back progresses at a high speed even under the condition that the wafer temperature is lower than that in the above-described Embodiment 4, and the TiN barrier metal 4 is used.
The formation of sulfur nitride based compounds on the exposed surface of Al was promoted. As a result, the Blk-W layer 5 can be etched back at high speed and with high selectivity while suppressing the loading effect.

The present invention has been described above based on the five embodiments, but the present invention is not limited to these embodiments. For example, as the bromine-based compound contained in the etching gas, in addition to HBr, S ₂ Br ₂ described above, Br ₂ , BBr ₃ , CBr ₄ , SiBr ₄ , CH
Br ₃ , SBr ₂ , S ₃ Br ₂ or the like can be used.

Fluorine compounds contained in the etching gas include SF ₆ , S ₂ F ₂ and NF ₃ , S.
F ₂ , SF ₄ , S ₂ F _10, etc. can be used. A rare gas such as He or Ar is added to the etching gas,
You may make it obtain a cooling effect, a sputtering effect, a dilution effect, etc. The refractory metal layer is made of Mo in addition to the W layer described above.
It may be a layer, a Ti layer, a Ta layer, or the like.

As the Ti-based barrier metal, one having a commonly used composition or constitution can be appropriately selected and used.
Further, at the time of over-etching, it is possible to achieve a higher selectivity to the ground by reducing the RF bias power or increasing the RF frequency.

[0047]

As is apparent from the above description, according to the dry etching method of the present invention, the blanket CV is used.
Etching back of the refractory metal layer formed by the D method
It can be carried out while suppressing the loading effect extremely well and maintaining a high selectivity for the Ti-based barrier metal. This makes it possible to form a highly reliable plug in the connection hole formed in the interlayer insulating film.

Therefore, the present invention is extremely useful for manufacturing a semiconductor device which is designed based on a fine design rule and which requires high integration, high performance and high reliability.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a process in which the dry etching method of the present invention is applied to etch back a Blk-W layer laminated with a TiN barrier metal in the order of steps, and FIG. Formed state,
(B) shows a state where the Blk-W layer is just etched, (c) shows a state where the Blk-W layer is over-etched, and (d) shows a state where the TiN barrier metal is etched back.

FIG. 2 is a schematic cross-sectional view for explaining a problem in the conventional etch back of a Blk-W layer, (a) of FIG.
The state in which the k-W layer is formed, (b) the surface morphology of the barrier metal is deteriorated, and the state in which the Blk-W layer is eroded, (c) the surface morphology of the interlayer insulating film is deteriorated, and
The lk-W layer and the TiN barrier metal are eroded.

FIG. 3 is a schematic cross-sectional view for explaining another problem in the conventional etch back of the Blk-W layer, showing a state where the surface morphology of the wafer is deteriorated and a TiN barrier metal is infiltrated.

[Explanation of symbols]

1 ... silicon substrate 2 ... impurity diffusion regions 3 ... SiO ₂ interlayer insulating film 3a ... connection hole 4 ... TiN barrier metal 5 ... Blk-W layer

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display area H01L 21/3205

Claims (4)

[Claims] 1. A laminated wiring layer formed by laminating a titanium-based barrier metal and a refractory metal layer in this order, and etching back a laminated wiring layer formed so as to fill a connection hole opened in an interlayer insulating film substantially flat. The dry etching method has a first step of etching back the refractory metal layer using an etching gas containing at least a bromine-based compound, and a second step of etching back the titanium-based barrier metal. And a dry etching method. 2. The dry etching method according to claim 1, wherein in the first step, the etching gas further contains a fluorine compound. 3. A laminated wiring layer formed by laminating a titanium-based barrier metal and a refractory metal layer in this order, and etching back a laminated wiring layer formed so as to bury a connection hole opened in an interlayer insulating film substantially flat. In the dry etching method, a first step of etching back the refractory metal layer substantially immediately before the titanium-based barrier metal is exposed using an etching gas containing at least a fluorine-based compound, and at least a bromine-based compound Dry etching comprising: a second step of over-etching the refractory metal layer while heating the substrate to be etched using an etching gas; and a third step of etching back the titanium-based barrier metal. Method. 4. The dry etching method according to claim 3, wherein in the second step, the etching gas further contains a fluorine compound.