JP2003234307A - Etching method, substrate cleaning method and method for manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent tungsten from being melted and surely clean a substrate in a silicide formation step for a substrate provided with elements which include a tungsten. <P>SOLUTION: A Co silicide layer 17 is formed as a cap layer in a specified region of a silicon substrate 1 provided with a polymetal gate electrode 9 including tungsten by using a TiN film 16, and the TiN film 16 is wet-etched using an H<SB>2</SB>SO<SB>4</SB>solution, for example, so that a TiN/W selection ratio becomes 5 or larger. After the TiN film 16 is removed, an H<SB>2</SB>SO<SB>4</SB>solution is used, for example, to clean the silicon substrate 1 so that the respective etching rates of the tungsten and Co silicide layer 17 become 0.3 nm/min or lower. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning an electronic device provided with a component containing tungsten, and more particularly to a low resistance polymetal gate electrode structure (W / W).
N _X / Poly-Si multilayer structure, etc.) or to a cleaning method for manufacturing a semiconductor device having a metal gate electrode structure (W / WN _X laminated structure, etc.) and a metal silicide layer.

[0002]

2. Description of the Related Art In recent years, miniaturization, high density, high speed, low power consumption, etc. have been promoted in VLSI devices. In the process of manufacturing a VLSI device, M
By reducing the resistance of the gate electrode of the OS transistor, the speed of the VLSI device can be further increased. In order to reduce the resistance of the gate electrode of a MOS transistor, in place of the conventional polysilicon gate electrode or silicide gate electrode, a metal containing no silicon, specifically, a polymetal gate electrode using a refractory metal or Metal gate electrodes have been developed. The structure of the polymetal gate electrode is, for example, W / WN _X in which a tungsten (W) film, a tungsten nitride (WN _X ) film, and a polysilicon (Poly-Si) film are sequentially deposited on a gate oxide film.
/ Poly-Si laminated structure or W on the gate oxide film
A W / TiN / Poly-Si laminated structure in which a film, a titanium nitride (TiN) film, and a Poly-Si film are sequentially deposited is used. As the structure of the metal gate electrode, for example, a W / WN _X laminated structure in which a W film and a WN _X film are sequentially deposited on a gate oxide film is used.

By the way, in many cases, the surface portions of the source region and the drain region in the MOS transistor are silicidized to reduce the resistance. A conventional silicide forming method using, for example, cobalt as a silicide forming metal is as follows. (Step 1) On a silicon substrate provided with a gate electrode,
A cobalt film and a titanium nitride film are sequentially deposited. (Step 2) First RTA (rapid
thermal annealing) treatment is performed to react the surface regions of the source region and the drain region on the silicon substrate with the cobalt film to form cobalt silicide (C
o ₂ Si) layer is formed. At this time, the titanium nitride film is
It functions as a cap film for preventing the oxidation of the cobalt film. (Step 3) The unreacted portion of the cobalt film and the titanium nitride film are removed by wet etching using an APM solution, SPM solution, HPM solution, or the like. (Step 4) A second RTA process is performed on the silicon substrate to change the composition of the cobalt silicide layer from Co ₂ Si to CoSi ₂ . (Step 5) The silicon substrate is washed with an APM solution, an SPM solution or the like to remove particles and the like.

[0004]

By the way, in the insulating side wall covering the side surface of the gate electrode, pinholes are formed due to particles adhering to the gate electrode or scratches generated on the gate electrode. There is a case.

However, when the above-described conventional silicide forming step is performed on the silicon substrate provided with the polymetal gate electrode or the metal gate electrode, the sidewall pin is formed in (step 3) or (step 5). The etching solution or the cleaning solution reaches the gate electrode through the hole. As a result, the hydrogen peroxide solution (H ₂ O ₂ ) contained in the APM solution or the SPM solution dissolves the tungsten forming the gate electrode, resulting in a decrease in yield.

In view of the above, it is an object of the present invention to reliably clean a substrate while preventing the dissolution of tungsten in the step of forming a silicide on a substrate provided with a component containing tungsten.

[0007]

In order to achieve the above-mentioned object, the etching method according to the present invention is a method of etching a tungsten film after forming a titanium nitride film on a substrate provided with a component containing tungsten. A step of performing wet etching on the titanium nitride film so that the ratio of the etching rate of the titanium nitride film to 5 is 5 or more.

According to the etching method of the present invention, the ratio of the etching rate of the titanium nitride film to the etching rate of tungsten is 5 or more for the titanium nitride film formed on the substrate having the constituent element containing tungsten. Wet etching is performed. Therefore, even after the metal silicide layer is formed on the substrate by using the titanium nitride film as the cap film, the titanium nitride film can be selectively removed while suppressing the dissolution of tungsten, and thus the substrate can be reliably cleaned. it can.

In the etching method of the present invention, the step of performing wet etching is preferably performed using a mixed solution of sulfuric acid and water (sulfuric acid solution) at a temperature of 70 ° C. or higher.

By doing so, the ratio of the etching rate of the titanium nitride film to the etching rate of tungsten is certainly 5 or more. At this time, the concentration of sulfuric acid in the sulfuric acid solution may be 0.1% by mass or more and less than 100% by mass. Further, if the sulfuric acid solution does not substantially contain the hydrogen peroxide solution, the dissolution of tungsten can be surely prevented.

In the present specification, the solution does not substantially contain hydrogen peroxide water, specifically, the liquid liquid contains hydrogen peroxide water (concentration 30% by mass) in a volume ratio of 0.2. It does not contain more than about%.

According to the substrate cleaning method of the present invention, after the metal silicide layer is formed on the substrate provided with the constituent element containing tungsten, the etching rate of tungsten is 0.3 nm / min or less and the metal silicide layer is etched. A step of cleaning the substrate is provided so that the rate is 0.3 nm / min or less.

According to the substrate cleaning method of the present invention, the etching rate of tungsten is 0. 0 for a substrate on which a constituent element containing tungsten and a metal silicide layer are formed.
Cleaning is performed so that the etching rate is 3 nm / min or less and the etching rate of the metal silicide layer is 0.3 nm / min or less. Therefore, it is possible to remove the particles and the like adhering to the substrate while suppressing the dissolution of the tungsten and the metal silicide layers, and thereby to reliably clean the substrate.

In the substrate cleaning method of the present invention, the cleaning step is preferably performed using a cleaning liquid that does not substantially contain hydrogen peroxide solution.

In this way, the melting of tungsten can be reliably prevented. At this time, as the cleaning liquid, for example, a mixed liquid of tetramethylammonium hydroxide (hereinafter referred to as TMAH) and water (TMAH concentration: about 0.01 to 5.0 mass%), aqueous ammonia (ammonia concentration: 0) It is preferable to use a mixed solution of sulfuric acid and water (sulfuric acid concentration: 0.1 to 100% by mass) or the like. By doing so, the etching rate of each of the tungsten and the metal silicide layer is surely set to 0.3 nm / min or less.

A first method for manufacturing a semiconductor device according to the present invention comprises a step of sequentially forming a metal film and a titanium nitride film on a semiconductor substrate provided with a gate electrode containing tungsten, and a heat treatment for the semiconductor substrate. And forming a metal silicide layer by reacting predetermined regions on both sides of the gate electrode in the semiconductor substrate with the metal film, and nitriding the etching rate of tungsten after the step of forming the metal silicide layer. Wet etching is performed on the titanium nitride film so that the etching rate ratio of the titanium film is 5 or more.

According to the first method of manufacturing a semiconductor device, a metal silicide layer is formed by using a titanium nitride film as a cap film in a predetermined region of a semiconductor substrate provided with a gate electrode containing tungsten, and then a tungsten film is formed. Wet etching is performed on the titanium nitride film so that the ratio of the etching rate of the titanium nitride film to the etching rate is 5 or more. Therefore, the titanium nitride film can be selectively removed while suppressing the dissolution of tungsten contained in the gate electrode, so that the semiconductor substrate can be reliably cleaned without lowering the yield.

In the first method of manufacturing a semiconductor device, the step of performing wet etching is preferably performed using a mixed solution of sulfuric acid and water (sulfuric acid solution) at a temperature of 70 ° C. or higher.

By so doing, the ratio of the etching rate of the titanium nitride film to the etching rate of tungsten is certainly 5 or more. At this time, the concentration of sulfuric acid in the sulfuric acid solution may be 0.1% by mass or more and less than 100% by mass. Further, if the sulfuric acid solution does not substantially contain the hydrogen peroxide solution, the dissolution of tungsten can be surely prevented.

In the first method of manufacturing a semiconductor device, the metal film is preferably made of cobalt or titanium.

By doing so, the cobalt silicide layer or the titanium silicide layer can be reliably formed.

In the first method of manufacturing a semiconductor device, the heat treatment is preferably RTA treatment.

In this way, the metal silicide layer can be reliably formed by the reaction between the semiconductor substrate and the metal film.

A second method of manufacturing a semiconductor device according to the present invention comprises a step of sequentially forming a metal film and a titanium nitride film on a semiconductor substrate provided with a gate electrode containing tungsten, and a step of forming a metal film and a titanium nitride film on the semiconductor substrate. The step of forming a metal silicide layer by reacting a predetermined region on both sides of the gate electrode on the semiconductor substrate with the metal film by performing the heat treatment of No. 1 and the unreacted portion of the titanium nitride film and the metal film are selected. The second heat treatment on the semiconductor substrate after the selective removal, and the etching rate of tungsten is 0.3 nm / min or less and the etching rate of the metal silicide layer is 0.3 nm / min or less. , A step of cleaning the semiconductor substrate that has been subjected to the second heat treatment.

According to the second method of manufacturing a semiconductor device, after a metal silicide layer is formed using a titanium nitride film as a cap film in a predetermined region of a semiconductor substrate provided with a gate electrode containing tungsten, titanium nitride is formed. After removing the film, the etching rate of tungsten is 0.3.
The semiconductor substrate is cleaned so that the etching rate of the metal silicide layer becomes 0.3 nm / min or less and the etching rate of the metal silicide layer becomes 0.3 nm / min or less. For this reason, the particles and the like adhering to the semiconductor substrate can be removed while suppressing the dissolution of the tungsten and the metal silicide layer contained in the gate electrode, so that the semiconductor substrate can be reliably cleaned without lowering the yield.

In the second method of manufacturing a semiconductor device, the step of cleaning is preferably performed using a cleaning liquid that does not substantially contain hydrogen peroxide solution.

In this way, the melting of tungsten can be surely prevented. At this time, as the cleaning liquid, for example, a mixed liquid of TMAH and water (TMAH concentration: 0.01
To about 5.0% by mass), aqueous ammonia (ammonia concentration: about 0.1 to 5.0% by mass), a mixed solution of sulfuric acid and water (sulfuric acid concentration: 0.1 to 100% by mass), or the like is used. It is preferable. By doing so, the etching rate of each of the tungsten and the metal silicide layer is surely set to 0.3 nm / min or less.

In the second method of manufacturing a semiconductor device, the metal film is preferably made of cobalt or titanium.

By doing so, the cobalt silicide layer or the titanium silicide layer can be reliably formed.

In the second method of manufacturing a semiconductor device, the first heat treatment is preferably RTA treatment.

By doing so, the metal silicide layer can be reliably formed by the reaction between the semiconductor substrate and the metal film.

In the second method of manufacturing a semiconductor device, the second heat treatment is preferably RTA treatment.

In this way, a low resistance metal silicide layer can be formed.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing the embodiments of the present invention, the etching method of the present invention and the substrate cleaning method of the present invention used in the embodiments of the present invention will be described.

(Etching Method of the Present Invention) The etching method of the present invention is characterized in that it is formed as a cap film in a silicide forming step on a substrate (for example, a silicon substrate) provided with a component containing tungsten (for example, a gate electrode). The titanium nitride film thus formed is wet-etched using a mixed solution of sulfuric acid and water (hereinafter referred to as H ₂ SO ₄ solution).

[Table 1] shows the basic characteristics (wet etching characteristics) of the H ₂ SO ₄ solution used in the etching method of the present invention, the HPM solution and APM which have been conventionally used for removing the titanium nitride (TiN) film. The result evaluated by comparing with the wet etching characteristic of each of the solution and the SPM solution is shown.

[0037]

[Table 1]

In Table 1, as the wet etching characteristics of each etching solution, the TiN film, the tungsten (W) film, and the cobalt silicide (CoSi ₂ ) film under the predetermined conditions (concentration and temperature) are used. The etching rate is shown. Here, TiN film and W
Each of the films is formed on the wafer by a PVD method with a thickness of about 100 nm via a thermal oxide film. Also,
The Co ₂ Si film is a C sequentially deposited on a silicon wafer.
RT of about 400-500 ° C for o film and TiN film
It is formed by performing the A treatment. Further, fluorescent X-rays are used in the film thickness measurement for calculating the etching rate.

As shown in [Table 1], when the H ₂ SO ₄ solution is used, the etching rate of the TiN film increases as the etching temperature increases, while the etching rate of the W film has a small value itself and is temperature dependent. The nature is also small. Therefore, it is understood that the TiN film can be removed while suppressing the dissolution of the W film by using the high temperature H ₂ SO ₄ solution as the etching solution.

Further, as shown in [Table 1], when an HPM solution, an APM solution or an SPM solution, that is, an etching solution containing H ₂ O ₂ is used, a large value can be obtained as the etching rate of the TiN film. Since the etching rate of the film is also high, the TiN film cannot be removed while suppressing the dissolution of the W film.

As shown in [Table 1], when using the H ₂ SO ₄ solution, the HPM solution, APM solution or SPM solution is also used.
Even when a solution is used, the etching rate of the Co ₂ Si film is so large that it can be ignored.

Based on the results shown in [Table 1], [Table 2] shows the etching selection ratio of the TiN film to the W film (T to the etching rate of the W film) for each etching solution.
The result of calculating the etching rate ratio of the iN film is shown.

[0043]

[Table 2]

As shown in [Table 2], when the H ₂ SO ₄ solution is used, the etching selection ratio of the TiN film to the W film becomes higher as the etching temperature rises. In particular, when the etching temperature is 70 ° C. or higher, the etching selection ratio of the TiN film to the W film exceeds 5. Therefore, it is very effective to use a H ₂ SO ₄ solution at 70 ° C. or higher to remove the TiN film formed as the cap film in the silicide formation process on the substrate provided with the gate electrode containing tungsten. is there.

On the other hand, as shown in [Table 2], when the conventional HPM solution, APM solution or SPM solution is used, the etching selection ratio of the TiN film to the W film is much lower than 1, so that the gate electrode The TiN film cannot be removed without melting the tungsten contained in the TiN film.

(Substrate Cleaning Method of the Present Invention) The substrate cleaning method of the present invention is characterized by a substrate (for example, a silicon substrate) provided with a component containing tungsten (for example, a gate electrode).
After the metal silicide layer is formed thereon, a cleaning liquid that does not substantially contain hydrogen peroxide water, for example, a mixed liquid of TMAH and water (hereinafter referred to as TMAH solution), ammonia (N
H ₄ OH) water or H ₂ SO ₄ solution is used to clean the substrate.

[Table 3] shows the results of evaluating the basic characteristics (etching characteristics) of each cleaning solution used in the substrate cleaning method of the present invention.

[0048]

[Table 3]

In [Table 3], the etching characteristics of each cleaning solution are as follows: the W film, the titanium silicide (TiSi ₂ ) film, and the cobalt silicide (CoSi ₂ ) film under predetermined conditions (concentration and temperature). The etching rate is shown.

As shown in [Table 3], each of the W film, the TiSi ₂ film and the CoSi ₂ film was substantially etched when either the TMAH solution, the ammonia water or the H ₂ SO ₄ solution was used. Never. Note that, here, the term "not substantially etched" means that the amount of etching by cleaning for about 5 to 10 minutes is a gate length (minimum 10 min.
It is sufficiently smaller than 10% of about 0 nm), for example, the etching rate is about 0.3 nm / min or less.

[Table 4] compares the particle removing ability of each cleaning solution used in the substrate cleaning method of the present invention under predetermined conditions (concentration, temperature and cleaning time) with the particle removing ability of the conventional APM solution. The result of evaluation is shown.

[0052]

[Table 4]

The particle removing ability shown in [Table 4] is specifically obtained as follows. That is, first, hydrofluoric acid (HF) is applied to the natural oxide film formed on the evaluation wafer made of Bare-Si.
Wet etching is performed. As a result, the surface of the evaluation wafer becomes hydrophobic. Then, the particle size is 0.
After coating about 5000 PSL (Polystyrene latex) particles of about 25 μm on the evaluation wafer, the evaluation wafer is left for one week to form a natural oxide film on the evaluation wafer. After that, the evaluation wafer is cleaned using each of the cleaning solutions described above, and then P on the evaluation wafer is cleaned.
The number of SL particles is measured by a particle counter (detection sensitivity: 0.20 μm or more), and the removal rate of PSL particles is calculated as the particle removal ability.

As shown in [Table 4], no matter whether the TMAH solution, the aqueous ammonia or the H ₂ SO ₄ solution was used, the particle removal rate was 90% or more, that is, the particles equivalent to the conventional APM solution were used. Removal capacity is obtained. That is, according to the results shown in [Table 3] and [Table 4], after forming the metal silicide layer on the substrate provided with the gate electrode containing tungsten, the substrate was cleaned without dissolving the tungsten and the metal silicide layer. It is very effective to use a TMAH solution, aqueous ammonia, or a H ₂ SO ₄ solution for the conversion.

(First Embodiment) A method for manufacturing a semiconductor device according to a first embodiment of the present invention will be described below with reference to the drawings, taking silicide formation on a substrate provided with a polymetal gate electrode as an example. explain. The first
The method of manufacturing a semiconductor device according to the above embodiment uses the above-described etching method of the present invention.

FIGS. 1A to 1D and FIGS. 2A to 2C.
3A to 3C are sectional views showing each step of the method for manufacturing the semiconductor device according to the first embodiment.

First, as shown in FIG. 1A, an element isolation oxide film 2 is formed on a silicon (Si) substrate 1, and n
The MOSFET formation region R _nmos and the pMOSFET formation region R _{pm os} are partitioned. Thereafter, a P-well 4 in the nMOSFET formation region R _nmos to form the N-well 3 in the pMOSFET formation region R _pmos. After that, a gate oxide film 5 made of a silicon oxide film is formed on the silicon substrate 1, and then, as shown in FIG. 1B, a polysilicon film 6 and a W / WN _x laminated film are formed on the silicon substrate 1. Membrane 7
(A laminated film of a lower WN _X film and an upper W film),
And the silicon nitride film 8 are sequentially formed. The polysilicon film 6 and the W / WN _x laminated film 7 serve as a material for the polymetal gate electrode, and the silicon nitride film 8 serves as a hard mask material for forming the gate electrode.

Next, as shown in FIG. 1C, the silicon nitride film 8, the W / WN _x laminated film 7 and the polysilicon film 6 are patterned to form a polymetal gate electrode 9 on each MOSFET formation region. To form. Here, for simplicity,
The patterned silicon nitride film 8 and the like are referred to as a polymetal gate electrode 9. Then each MOSFET
Low-energy extension implantation is performed on the formation region to form a shallow diffusion layer (not shown).

Next, as shown in FIG. 1D, an insulating sidewall 10 is formed on the side surface of each polymetal gate electrode 9.
After the formation of the pMOSFE, as shown in FIG.
In the T formation region R _pmos , the P-type impurity diffusion layer 11 to be the source / drain region of the pMOSFET is formed and
In the nMOSFET formation region R _nmos , the N-type impurity diffusion layer 12 to be the source / drain region of the nMOSFET is formed.

Next, as shown in FIG. 2B, after the insulating film 13 is deposited on the entire surface of the silicon substrate 1 by the CVD method, other regions (non-silicided region) other than the silicide layer formation region are formed. A resist pattern 14 covering the area) is formed.

Next, as shown in FIG. 2C, the insulating film 13 is wet-etched using, for example, hydrofluoric acid using the resist pattern 14 as a mask to form a silicide layer forming region ( For example, the upper portion of the P-type impurity diffusion layer 11) is removed. As a result, the P-type impurity diffusion layer 11 in the silicide layer formation region is exposed from the patterned insulating film 13. afterwards,
Resist pattern 14 used as an etching mask
Are removed by sequentially using plasma ashing treatment and cleaning.

Next, after cleaning the silicon substrate 1 by cleaning before film formation, as shown in FIG. 3A, a Co film 15 and a TiN film 16 are continuously formed over the entire surface of the silicon substrate 1. Then, a film is formed. After that, the silicon substrate 1 is subjected to heat treatment, for example, RTA treatment at about 500 ° C., so that the P-type impurity diffusion layer 1 outside the patterned insulating film 13 is formed.
By reacting the surface portion of No. 1 with the Co film 15, the Co silicide layer 17 is formed as shown in FIG. At this time, the TiN film 16 functions as a cap film for preventing oxidation of the Co film 15. At this time, the Co silicide layer 17 is mainly made of Co ₂ Si.

Next, as shown in FIG. 3C, the TiN film 16 and the unreacted portion of the Co film 15 are selectively removed.
In the first embodiment, the above-mentioned “etching method of the present invention” is used in this step. Specifically, for example, a H ₂ SO ₄ solution at 120 ° C. is added to 30 so that the ratio of the etching rate of the TiN film 16 to the etching rate of tungsten contained in the polymetal gate electrode 9 is 5 or more.
Wet etching is performed on the TiN film 16 and the unreacted portion of the Co film 15 for a minute.

That is, according to the first embodiment, TiN is used as a cap film in a predetermined region of the silicon substrate 1 on which the polymetal gate electrode 9 containing tungsten is provided.
After the Co silicide layer 17 is formed using the film 16, H _{2 is} applied to the TiN film 16 so that the ratio of the etching rate of the TiN film 16 to the etching rate of tungsten (TiN / W selection ratio) is 5 or more. Wet etching is performed using a SO ₄ solution. Therefore, even when a pinhole is formed in the sidewall 10 formed on the side surface of the polymetal gate electrode 9, the TiN film 16 is selected while suppressing the dissolution of tungsten contained in the polymetal gate electrode 9. Since the silicon substrate 1 can be removed as desired, the silicon substrate 1 can be reliably cleaned without lowering the yield.

In the first embodiment, the TiN film 1
A H ₂ SO ₄ solution was used as an etching solution for removing No. 6, but instead of this, another etching solution having a TiN / W selectivity of 5 or more, for example, a mixed solution of hydrofluoric acid and water (hereinafter , Referred to as a hydrofluoric acid solution) or the like. Further, two or more etching solutions selected from the H ₂ SO ₄ solution, the hydrofluoric acid solution and the TMAH solution may be sequentially used. However,
In order to prevent the metal silicide layer (Co silicide layer 17 in this embodiment) from being substantially etched when the TiN film 16 is removed, in other words, the etching rate of the metal silicide layer is, for example, 0.3 nm /
It is preferable to use a H ₂ SO ₄ solution in order to reduce the amount to about min or less.

Further, in the first embodiment, H ₂ SO ₄
The etching temperature when removing the TiN film 16 using a solution is preferably 70 ° C. or higher. By so doing, the TiN / W selection ratio is certainly 5 or more. Also,
The sulfuric acid concentration in the H ₂ SO ₄ solution may be 0.1% by mass or more and less than 100% by mass. Also, at this time, H
It is preferred that the ₂ SO ₄ solution be substantially free of H ₂ O ₂ . By so doing, it is possible to reliably prevent the tungsten contained in the polymetal gate electrode 9 from being melted.

Further, in the first embodiment, the Co film 15 is used as the metal for forming a silicide to form the Co silicide layer 17, but a titanium (Ti) film or a nickel (Ni) film is used instead. Alternatively, a Ti silicide layer or a Ni silicide layer may be formed.

Further, in the first embodiment, the surface portion of the silicon substrate 1 (specifically, the surface portion of the P-type impurity diffusion layer 11) and the Co film 15 are caused to react with each other, so that the Co silicide layer 1 is formed.
Although RTA processing was performed to form 7, other heat treatment may be performed instead of RTA processing. The temperature of the heat treatment such as the RTA treatment is set to the silicon substrate 1 and the TiN film 16
It is preferable to set the temperature to about 400 to 500 ° C. so that the reaction does not occur and the Co silicide layer 17 is surely formed.

In the first embodiment, each cleaning step performed after the polymetal gate electrode 9 is formed (for example, the cleaning step after removing the resist pattern 14 or the deposition of the Co film 15 and the TiN film 16). It is preferable to use a cleaning liquid which does not substantially contain H ₂ O ₂ in the cleaning step (1). By so doing, it is possible to reliably prevent the tungsten contained in the polymetal gate electrode 9 from being melted.

(Second Embodiment) A method of manufacturing a semiconductor device according to a second embodiment of the present invention will be described below by taking silicide formation on a substrate provided with a polymetal gate electrode as an example. The semiconductor device manufacturing method according to the second embodiment uses the substrate cleaning method of the present invention described above. In addition, in the second embodiment, FIGS. 1A to 1D, 2A to 2C, and 3A.
To (c), the method of manufacturing the semiconductor device according to the first embodiment forms the Co silicide layer 17 and T
It is assumed that the selective removal of the iN film 16 and the unreacted Co film 15 has been completed.

In the second embodiment, first, the silicon substrate 1 is heat-treated, for example, RTA at about 800 ° C.
Processing is performed to change the composition of the Co silicide layer 17 to Co ₂
Change from Si to CoSi ₂ . Thereby, the resistance of the Co silicide layer 17 can be reduced.

Next, the putty deposited on the silicon substrate 1
The silicon substrate 1 is washed in order to remove particles and the like.
It In the second embodiment, the above-mentioned "book" is used in this step.
The substrate cleaning method of the invention "is used. Specifically, polymeta
Of the tungsten contained in the rugate electrode 9.
Is 0.3 nm / min or less and a Co silicide layer
The etching rate of 17 will be 0.3 nm / min or less
Sea urchin, for example, H at 90 ℃ ₂SO_FourUse the solution for 10 minutes
The recon substrate 1 is washed.

That is, according to the second embodiment, TiN is used as a cap film in a predetermined region of the silicon substrate 1 on which the polymetal gate electrode 9 containing tungsten is provided.
After forming the Co silicide layer 17 using the film 16, T
After removing the iN film 16, the silicon substrate 1 is cleaned so that the etching rate of tungsten is 0.3 nm / min or less and the etching rate of the Co silicide layer 17 is 0.3 nm / min or less. Therefore, even if a pinhole is formed in the sidewall 10 formed on the side surface of the polymetal gate electrode 9, the dissolution of tungsten contained in the polymetal gate electrode 9 and the dissolution of the Co silicide layer 17 are suppressed. At the same time, since particles and the like attached to the silicon substrate 1 can be removed, the silicon substrate 1 can be reliably cleaned without lowering the yield.

In the second embodiment, the TiN film 1 is used.
After removing 6 and the unreacted Co film 15, heat treatment for improving the composition of the Co silicide layer 17 is performed. Immediately after that, the “substrate cleaning method of the present invention” was performed. But,
The timing of performing the “substrate cleaning method of the present invention” is not particularly limited. For example, the Co silicide layer 17
After depositing an interlayer insulating film on the silicon substrate 1 on which the film was formed, a contact hole is formed in the interlayer insulating film so as to reach the Co silicide layer 17, and immediately after that, the “substrate cleaning method of the present invention” is performed. Good.

Further, in the second embodiment, it is preferable that the cleaning liquid used in the “method for cleaning a substrate of the present invention” does not substantially contain hydrogen peroxide solution. This way,
It is possible to reliably prevent the dissolution of tungsten contained in the polymetal gate electrode 9.

Further, in the second embodiment, the H ₂ SO ₄ solution was used as the cleaning liquid used in the “substrate cleaning method of the present invention”, but instead of this, the tungsten and Co silicide layers 17 are etched respectively. Rate is 0.3n
Other cleaning solutions having a flow rate of m / min or less, such as TMAH solution, aqueous ammonia, or a mixed solution of hydrochloric acid and water (hereinafter referred to as hydrochloric acid solution) may be used. In addition, H ₂ SO ₄ solution, T
Two or more cleaning solutions of the MAH solution, the aqueous ammonia solution and the hydrochloric acid solution may be sequentially used.

Further, in the second embodiment, when another metal silicide layer such as a Ti silicide layer is formed instead of the Co silicide layer 17, the etching rate of each of tungsten and the other metal silicide layer is increased. Is required to be 0.3 nm / min or less. In this case also, the H ₂ SO ₄ solution, TMAH solution,
Aqueous ammonia or hydrochloric acid solution can be used.

Further, in the second embodiment, H ₂ SO ₄
The concentration of sulfuric acid in the solution is 0.1% by mass or more and 100
It may be less than mass%. When using a TMAH solution, the TMAH concentration is 0.01% by mass or more and 5.0 or less.
It may be mass% or less. When using ammonia water, the ammonia concentration is 0.1% by mass or more and 5.0 or less.
It may be mass% or less.

Further, in the second embodiment, H ₂ SO ₄
The washing temperature using the solution is not particularly limited and may be about room temperature, for example. TMAH solution,
The same applies when using aqueous ammonia or hydrochloric acid solution.

Further, in the second embodiment, the RTA treatment was performed in order to change the composition of the Co silicide layer 17 from Co ₂ Si to CoSi ₂ , but instead of this, another heat treatment may be performed. Good. Further, the temperature of heat treatment such as RTA treatment is preferably set to about 800 ° C. so that the composition change of the Co silicide layer 17 is surely caused.

In the first or second embodiment,
Although the silicide formation in the silicon substrate 1 provided with the polymetal gate electrode 9 containing tungsten is targeted, the present invention is not limited to this, and a silicide formation in a component provided with tungsten, for example, a substrate provided with a metal gate electrode containing tungsten. Similar effects can be obtained by targeting.

[0082]

According to the present invention, in the silicide formation process on the substrate provided with the constituent element containing tungsten, the titanium nitride film used as the cap film or the substrate is deposited while suppressing the dissolution of tungsten. Since particles and the like can be removed, the substrate can be reliably cleaned without lowering the yield.

[Brief description of drawings]

1A to 1D are cross-sectional views showing each step of a method for manufacturing a semiconductor device according to a first embodiment of the present invention.

2A to 2C are cross-sectional views showing each step of the method for manufacturing a semiconductor device according to the first embodiment of the present invention.

3A to 3C are cross-sectional views showing respective steps of the method for manufacturing a semiconductor device according to the first embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Element isolation oxide film 3 N well 4 P well 5 Gate oxide film 6 Polysilicon film 7 W / WN _X laminated film 8 Silicon nitride film 9 Polymetal gate electrode 10 Sidewall 11 P type impurity diffusion layer 12 N type Impurity diffusion layer 13 Insulating film 14 Resist pattern 15 Co film 16 TiN film 17 Co silicide layer

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4M104 BB01 BB20 BB21 BB25 BB33                       CC01 CC05 DD02 DD64 DD80                       DD84 EE05 EE09 GG09 GG10                       GG14                 5F033 HH04 HH19 HH33 HH34 KK25                       KK27 MM05 MM08 MM13 QQ08                       QQ20 QQ28 QQ70 QQ73 QQ82                       QQ91 TT08 VV06 WW00 WW04                 5F043 AA40 BB30 DD07

Claims (29)

[Claims] 1. A titanium nitride film is formed on a substrate provided with a component containing tungsten, and then the titanium nitride film is adjusted so that a ratio of an etching rate of the titanium nitride film to an etching rate of the tungsten is 5 or more. An etching method comprising a step of performing wet etching on a film. 2. The etching method according to claim 1, wherein the step of performing the wet etching is performed using a mixed solution of sulfuric acid and water at a temperature of 70 ° C. or higher. 3. The concentration of sulfuric acid in the mixed solution is 0.
It is 1 mass% or more and less than 100 mass%, The etching method of Claim 2 characterized by the above-mentioned. 4. The etching method according to claim 2, wherein the mixed solution does not substantially contain hydrogen peroxide solution. 5. After forming a metal silicide layer on a substrate provided with a component containing tungsten, the etching rate of the tungsten is 0.3 nm / min or less and the etching rate of the metal silicide layer is less than 0.3 nm / min.
A method of cleaning a substrate, comprising a step of cleaning the substrate so as to be 3 nm / min or less. 6. The substrate cleaning method according to claim 5, wherein the cleaning step is performed using a cleaning liquid that does not substantially contain hydrogen peroxide solution. 7. The substrate cleaning method according to claim 6, wherein the cleaning liquid is a mixed liquid of tetramethylammonium hydroxide and water. 8. The substrate cleaning method according to claim 7, wherein the concentration of tetramethylammonium hydroxide in the mixed solution is 0.01% by mass or more and 5.0% by mass or less. 9. The substrate cleaning method according to claim 6, wherein the cleaning liquid is aqueous ammonia. 10. The substrate cleaning method according to claim 9, wherein the concentration of ammonia in the ammonia water is 0.1% by mass or more and 5.0% by mass or less. 11. The substrate cleaning method according to claim 6, wherein the cleaning liquid is a mixed liquid of sulfuric acid and water. 12. The concentration of sulfuric acid in the mixed solution is
The substrate cleaning method according to claim 11, wherein the content is 0.1% by mass or more and less than 100% by mass. 13. The gate electrode in the semiconductor substrate, wherein a step of sequentially forming a metal film and a titanium nitride film on a semiconductor substrate provided with a gate electrode containing tungsten and a heat treatment for the semiconductor substrate are performed. Forming a metal silicide layer by reacting a predetermined region on both sides of the metal film with the metal film, and etching the titanium nitride film with respect to the etching rate of the tungsten after the step of forming the metal silicide layer. And a step of performing wet etching on the titanium nitride film so that the ratio is 5 or more. 14. The method of manufacturing a semiconductor device according to claim 13, wherein the step of performing the wet etching is performed using a mixed solution of sulfuric acid and water at a temperature of 70 ° C. or higher. 15. The concentration of sulfuric acid in the mixed solution is
15. The method for manufacturing a semiconductor device according to claim 14, wherein the content is 0.1% by mass or more and less than 100% by mass. 16. The method of manufacturing a semiconductor device according to claim 14, wherein the mixed solution does not substantially contain hydrogen peroxide solution. 17. The method of manufacturing a semiconductor device according to claim 13, wherein the metal film is made of cobalt or titanium. 18. The method of manufacturing a semiconductor device according to claim 13, wherein the heat treatment is an RTA treatment. 19. The semiconductor substrate is formed by sequentially forming a metal film and a titanium nitride film on a semiconductor substrate provided with a gate electrode containing tungsten, and performing a first heat treatment on the semiconductor substrate. A step of forming a metal silicide layer by reacting a predetermined region on both sides of the gate electrode with the metal film, and after selectively removing the titanium nitride film and an unreacted portion of the metal film, Performing a second heat treatment on the semiconductor substrate, and setting the etching rate of the tungsten to 0.3 nm / min or less and the etching rate of the metal silicide layer to 0.3 nm / min or less. And a step of cleaning the semiconductor substrate subjected to the heat treatment of 2. 20. The method of manufacturing a semiconductor device according to claim 19, wherein the cleaning step is performed using a cleaning liquid that does not substantially contain hydrogen peroxide solution. 21. The method of manufacturing a semiconductor device according to claim 20, wherein the cleaning liquid is a mixed liquid of tetramethylammonium hydroxide and water. 22. The concentration of tetramethylammonium hydroxide in the mixed solution is 0.01% by mass.
22. The method for manufacturing a semiconductor device according to claim 21, wherein the content is at least 5.0 mass%. 23. The method of manufacturing a semiconductor device according to claim 20, wherein the cleaning liquid is aqueous ammonia. 24. The method of manufacturing a semiconductor device according to claim 23, wherein the concentration of ammonia in the ammonia water is 0.1% by mass or more and 5.0% by mass or less. 25. The method of manufacturing a semiconductor device according to claim 20, wherein the cleaning liquid is a mixed liquid of sulfuric acid and water. 26. The concentration of sulfuric acid in the mixed solution is
26. The method for manufacturing a semiconductor device according to claim 25, wherein the content is 0.1% by mass or more and less than 100% by mass. 27. The method of manufacturing a semiconductor device according to claim 19, wherein the metal film is made of cobalt or titanium. 28. The method of manufacturing a semiconductor device according to claim 19, wherein the first heat treatment is an RTA treatment. 29. The method of manufacturing a semiconductor device according to claim 19, wherein the second heat treatment is an RTA treatment.