JP3420743B2 - Semiconductor device and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having a gate electrode composed of a laminated film of a lower titanium nitride film and an upper tungsten film, and a method of manufacturing the same.

[0002]

2. Description of the Related Art With the recent progress in technology for higher integration and higher speed in semiconductor integrated circuits, miniaturization of MOSFETs has been advanced.

However, when the gate insulating film is made thinner along with the miniaturization of the MOSFET, a decrease in the driving force of the MOSFET becomes apparent in the conventional gate electrode made of a polycrystalline silicon film due to depletion of the gate electrode. come.

Therefore, in order to suppress this problem, a metal gate process using a metal film that does not cause depletion of the gate electrode as a gate electrode has been receiving attention in recent years. In this metal gate, since the resistance value of the material forming the gate electrode is low, it is effective from the viewpoint of reducing the delay in the gate electrode.

As one of the structures of the gate electrode, 10-2
Lower layer titanium nitride (TiN) having a thickness of about 0 nm
A laminated structure of a film and an upper tungsten (W) film having a thickness of about 50 to 100 nm is used.

Conventionally, as a method of forming a laminated film of a lower titanium nitride film and an upper tungsten film, WF ₆ is formed on a titanium nitride film deposited by a sputtering method.
A first method of depositing a tungsten film by a CVD method using a gas, a second method of similarly depositing a tungsten film on a titanium nitride film deposited by a sputtering method, and a chemical vapor deposition ( C
On the titanium nitride film deposited by the VD) method, WF ₆
A third method of depositing a tungsten film by a CVD method using a gas is known.

[0007]

However, according to the first or second method of depositing the titanium nitride film by the sputtering method, the insulating film which is formed below the titanium nitride film and serves as the gate insulating film is sputtered. There is a problem that the reliability of the gate insulating film is deteriorated because the particles are physically damaged.

According to the third method of depositing the tungsten film on the titanium nitride film deposited by the CVD method by the CVD method using WF ₆ gas, the gate insulating film is physically damaged by the sputtered particles. However, it has been pointed out that fluorine in the tungsten film deteriorates the reliability of the gate insulating film. That is, H.264. Yang et al., IED
M Tech Dig. (1997) pp. 459-4
62, when a tungsten film is formed by a CVD method using WF ₆ gas, a large amount of fluorine remains in the tungsten film, and in the heat treatment step performed after the formation of the tungsten film, the fluorine in the tungsten film is removed. It has been reported that the titanium nitride film passes through and diffuses into the gate insulating film, which deteriorates the reliability of the gate insulating film.

In view of the above, the present invention provides a method for forming a gate electrode composed of a laminated film of a lower titanium nitride film and an upper tungsten film without degrading the reliability of the gate insulating film. To aim.

[0010]

In order to achieve the above object, a method of manufacturing a semiconductor device according to the present invention comprises a step of forming a first insulating film to be a gate insulating film on a semiconductor substrate, and a first step. Forming a titanium nitride film on the insulating film by chemical vapor deposition, forming a tungsten film on the titanium nitride film by a sputtering method, and a laminated film including a tungsten film and a titanium nitride film. Is patterned to form a gate electrode made of the laminated film.

According to the method for manufacturing a semiconductor device of the present invention, since the titanium nitride film is formed by the CVD method on the first insulating film to be the gate insulating film, the first insulating film is physically formed. Since it is not damaged, the reliability of the gate insulating film made of the first insulating film is improved.

Further, since the tungsten film is formed by the sputtering method, the gate insulating film is deteriorated due to the fluorine contained in the tungsten film like the tungsten film formed by the CVD method using CF ₆ gas. It is possible to prevent the situation.

Further, since the tungsten film is formed by the sputtering method, the unevenness of the surface of the tungsten film is reduced. Therefore, the tungsten film and the titanium nitride film are patterned to form the gate electrode. The amount of over-etching can be reduced, which can prevent punch-through of the gate insulating film due to over-etching.

Therefore, according to the method of manufacturing a semiconductor device of the present invention, it is possible to form a gate electrode having a small resistance value without degrading the reliability of the gate insulating film.

In the method of manufacturing a semiconductor device according to the present invention, the step of forming the titanium nitride film preferably includes the step of subjecting the titanium nitride film to a heat treatment in an ammonia atmosphere.

In this way, the concentration of residual impurities existing in the titanium nitride film becomes low, so that the gate leak current increases even if the titanium nitride film is subjected to a heat treatment at about 1000 ° C. in a later step. It is possible to prevent the occurrence of film peeling on the surface of the gate insulating film.

In this case, the step of heat-treating the titanium nitride film is preferably performed in the same chamber in which the titanium nitride film is formed.

In this way, the concentration of residual impurities existing in the titanium nitride film can be lowered without increasing the number of processes.

In the method of manufacturing a semiconductor device according to the present invention, the step of forming the titanium nitride film may include the step of subjecting the titanium nitride film to a heat treatment at a temperature not lower than the film forming temperature of the titanium nitride film. preferable.

In this way, the concentration of residual impurities existing in the titanium nitride film becomes low, so that the gate leak current increases even if the titanium nitride film is heat-treated at about 1000 ° C. in the subsequent process. It is possible to prevent the occurrence of film peeling on the surface of the gate insulating film.

In this case, the heat treatment is preferably performed in an ammonia atmosphere.

By doing so, the concentration of residual impurities existing in the titanium nitride film can be further reduced.

In the method of manufacturing a semiconductor device according to the present invention, the step of forming the titanium nitride film is preferably carried out at a temperature of 600 ° C. or higher.

By doing so, the concentration of residual impurities existing in the titanium nitride film becomes low, so that the gate leak current increases even if the titanium nitride film is heat-treated at about 1000 ° C. in the subsequent step. It is possible to prevent the occurrence of film peeling on the surface of the gate insulating film.

In the method of manufacturing a semiconductor device according to the present invention, after the second insulating film is formed on the titanium nitride film between the step of forming the titanium nitride film and the step of forming the tungsten film. A step of patterning the second insulating film to form a capacitive insulating film, and a step of patterning the laminated film to form a gate electrode includes forming a capacitive upper electrode made of a tungsten film and forming a titanium nitride film. It is preferable to include a step of forming a capacitor lower electrode made of.

In this way, it is possible to form a semiconductor device including a capacitive element with less variation in electrode characteristics and less deterioration in high frequency characteristics without increasing the number of steps.

In the method of manufacturing a semiconductor device according to the present invention, after the second insulating film is formed on the titanium nitride film between the step of forming the titanium nitride film and the step of forming the tungsten film. And a step of patterning the second insulating film to form a hard mask made of the second insulating film on the element isolation region. The step of patterning the laminated film to form the gate electrode is titanium nitride. It is preferable to include a step of patterning the film using a hard mask to form a resistor made of a titanium nitride film.

By doing so, a semiconductor device having a resistor having a high sheet resistance value can be formed without increasing the number of steps.

In this case, the thickness of the second insulating film is preferably equal to or less than the height of the element isolation region protruding from the semiconductor substrate.

By doing so, the thickness of the tungsten film remaining on the side surface of the hard mask on the titanium nitride film is approximately the same as the thickness of the tungsten film remaining on the step portion of the element isolation region in the titanium nitride film. Because of the following, the tungsten film remaining on the side surface of the hard mask on the titanium nitride film is removed by overetching for removing the tungsten film remaining on the stepped portion of the element isolation region in the titanium nitride film. It is possible to prevent the characteristics of the resistor from varying.

A first semiconductor device according to the present invention comprises a lower gate electrode made of a titanium nitride film formed on a semiconductor substrate by a chemical vapor deposition method, and a sputtering method on the titanium nitride film. A stacked gate electrode composed of an upper layer gate electrode composed of a deposited tungsten film, a capacitor lower electrode composed of a titanium nitride film, a capacitor insulating film formed on the capacitor lower electrode, and the capacitor insulating film. And a capacitive element composed of a capacitive upper electrode made of a tungsten film formed on the above.

According to the first semiconductor device of the present invention,
A semiconductor device including a highly reliable gate electrode and a capacitor with less variation in electrode characteristics and less deterioration in high-frequency characteristics can be realized.

A second semiconductor device according to the present invention comprises a lower gate electrode made of a titanium nitride film formed by a chemical vapor deposition method on a semiconductor substrate and a sputtering method formed on the titanium nitride film. It is provided with a laminated gate electrode composed of an upper layer gate electrode composed of a deposited tungsten film and a resistor composed of a titanium nitride film.

According to the second semiconductor device of the present invention,
It is possible to realize a semiconductor device including a highly reliable gate electrode and a resistor having a high sheet resistance value.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) As a first embodiment of the present invention, a method for manufacturing a semiconductor device having an n-type MOSFET will be described below with reference to FIGS. To do.

First, as shown in FIG. 1A, for example, p
An element isolation region 11 is formed on the surface of a semiconductor substrate 10 made of a silicon substrate by a known method, and then a silicon oxynitride film 12 having a thickness of about 2 nm to be a gate insulating film is formed on the semiconductor substrate 10. To do.

Next, by using TiCl ₄ and NH ₃ as source gases and performing a CVD method at a film forming temperature of about 490 ° C., the silicon oxynitride film 12 is formed,
After forming the titanium nitride film 13 having a thickness of about 10 to 20 nm, the titanium nitride film 1 is formed by the sputtering method.
A tungsten film 14 having a thickness of about 100 nm is formed on the No. 3 film.

Next, as shown in FIG. 1B, the laminated film of the tungsten film 14 and the titanium nitride film 13 and the silicon oxynitride film 12 are patterned to form the tungsten film 14 and the titanium nitride film 13. A gate electrode 15 made of a laminated film is formed, and a gate insulating film 16 made of a silicon oxynitride film 12 is formed. Next, the semiconductor substrate 10
With the gate electrode 15 as a mask,
A type impurity is ion-implanted with an implantation energy of about 8 keV to form an n-type low-concentration impurity layer. Next, after a silicon nitride film having a thickness of about 50 nm is formed over the entire surface of the semiconductor substrate 10, the silicon nitride film is anisotropically etched to form side surfaces of the gate electrode 15. A sidewall 17 made of a silicon nitride film is formed,
Then, using the gate electrode 15 and the sidewall 17 as a mask, the semiconductor substrate 10 is doped with an n-type impurity such as arsenic by 4
Ion implantation is performed with an implantation energy of about 0 keV to form an n-type high-concentration impurity, and an impurity diffusion layer 18 formed of an n-type low-concentration impurity layer and a high-concentration impurity layer to be a source region or a drain region is formed.

Next, as shown in FIG. 1C, after depositing an interlayer insulating film 19 made of, for example, a silicon oxide film over the entire surface of the semiconductor substrate 10, a contact hole is formed in the interlayer insulating film 19. Form. Next, a conductive film having a barrier layer is deposited on the interlayer insulating film 19 so as to fill the contact hole, and then the conductive film is patterned to form the contact 20 and the wiring layer 21.

According to the first embodiment, the gate insulating film 1
Since the titanium nitride film 13 is formed on the silicon oxynitride film 12 to be 6 by the CVD method, the silicon oxynitride film 12 is not physically damaged. Therefore, the gate insulating film made of the silicon oxynitride film 12 is formed. The reliability of 16 is improved.

Further, since the titanium nitride film 13 is formed by the CVD method at a low temperature of about 490 ° C., the film forming rate of the titanium nitride film 13 becomes low. Therefore, the titanium nitride film 13 having a small film thickness can be formed with good controllability.

The tungsten film 14 is formed by sputtering.
Since the film is formed by the casting method, CF ₆CV using gas
Compared with the tungsten film formed by the D method, the tongue
Gate insulation due to fluorine contained in the stainless steel film 14
It is possible to prevent the film 16 from being deteriorated.

Further, the gate electrode 15 has a thickness of 10 to 20 n.
Since the thin titanium nitride film 13 having a thickness of about m and the thick tungsten film 14 having a low resistance value of about 100 nm are laminated, the resistance of the gate electrode 15 can be reduced.

2A and 2B show the titanium nitride film 13
2 shows the crystal structure of the tungsten film 14 formed on the tungsten film 14. FIG. 2A shows the tungsten film 1 formed by the CVD method.
4 is formed, and FIG. 2B is a case where the tungsten film 14 is formed by the sputtering method. As can be seen from the comparison between FIG. 2A and FIG. 2B, as the size of the unevenness of the film surface caused by the crystal grains, the tungsten film 14 formed by the sputtering method is formed by the CVD method. It is smaller than the deposited tungsten film 14.

Therefore, when the tungsten film 14 is formed by the sputtering method as in the first embodiment,
Since the amount of over-etching performed when forming the gate electrode 15 by patterning the laminated film of the tungsten film 14 and the titanium nitride film 13 can be reduced, the punch-through of the gate insulating film 16 due to over-etching can be suppressed.

(Second Embodiment) As a second embodiment of the present invention, a method of manufacturing a semiconductor device having an n-type MOSFET will be described below with reference to FIGS.

First, as shown in FIG. 1A, similarly to the first embodiment, after the element isolation region 11 is formed on the surface of the semiconductor substrate 10 made of, for example, a p-type silicon substrate, the semiconductor substrate is formed. A silicon oxynitride film 12 having a thickness of about 2 nm to be a gate insulating film is formed on 10.

Next, a mixed gas of TiCl ₄ and NH ₃ as a source gas is introduced into a chamber kept at a temperature of about 490 ° C., and a CVD method is used to deposit 10 to 10 on the silicon oxynitride film 12. A titanium nitride film 13 having a thickness of about 20 nm is formed. After that, while the semiconductor substrate 10 is continuously held in the chamber, the inside of the chamber is changed to the atmosphere of NH ₃ and the temperature inside the chamber is maintained at the film formation temperature of the titanium nitride film 13 (490 ° C.) or higher. In this state, the semiconductor substrate 10 is held for about 3 to 10 minutes.

Next, similarly to the first embodiment, 100 is formed on the titanium nitride film 13 by the sputtering method.
After forming the tungsten film 14 having a thickness of about nm, as shown in FIG. 1B, a laminated film of the tungsten film 14 and the titanium nitride film 13 and the silicon oxynitride film 1 are formed.
2 is patterned to form a gate electrode 15 and a gate insulating film 16.

Next, similarly to the first embodiment, after forming the sidewall 17 on the side surface of the gate electrode 15 and forming the impurity diffusion layer 18 to be the source region or the drain region in the semiconductor substrate 10, As shown in FIG. 1C, the interlayer insulating film 19, the contact 20, and the wiring layer 2
1 is formed.

By the way, when the titanium nitride film 13 is formed by a CVD method using a source gas composed of a mixed gas of TiCl ₄ and NH ₃ , a subsequent heat treatment, for example, the impurity diffusion layer 1 to be a source region or a drain region is performed.
I noticed the problem that the gate leak current increases due to the heat treatment at about 1000 ° C. for activating 8.

Therefore, after the titanium nitride film 13 is formed, 10
As a result of examining the reason why the leakage current increases when the heat treatment is performed at about 00 ° C., the following causes are found.

When the titanium nitride film 13 is formed by a CVD method using a source gas composed of a mixed gas of TiCl ₄ and NH ₃ , 6TiCl ₄ + 8NH ₃ → 6TiN + 24
Since the reaction of HCl + N ₂ occurs to form the titanium nitride film 13, chlorine remains in the titanium nitride film 13. Therefore, when the titanium nitride film 13 is subjected to heat treatment at about 1000 ° C., chlorine remaining in the titanium nitride film 13 diffuses into the gate insulating film 16 in the heat treatment process, which increases the gate leakage current. I found that

It has also been found that increasing the film thickness of the gate insulating film 16 increases the gate leakage current.

FIG. 3 shows a cross-sectional structure when a tungsten film 14 is formed on the titanium nitride film 13 formed as described above, and then a heat treatment at about 1000 ° C. is performed. As shown in FIG. 3, since the outward diffusion path of the residual chlorine vaporized from the titanium nitride film 13 is closed, the residual chlorine is left between the silicon oxynitride film 12 and the titanium nitride film 13 serving as the gate insulating film. It stays, and as a result, film peeling occurs on the surface of the gate insulating film. This problem is particularly remarkable when the titanium nitride film 13 is formed at a low temperature in order to improve the quality of the titanium nitride film 13.

By the way, as a method of reducing the residual chlorine in the titanium nitride film 13, a method of irradiating the titanium nitride film 13 with plasma is proposed in Japanese Patent No. 2803556. According to this method, Since the gate insulating film 16 is damaged by the plasma irradiation, the reliability of the gate insulating film 16 may be deteriorated.

In the second embodiment, the residual chlorine in the titanium nitride film 13 is reduced and the titanium nitride film 13 is heat-treated at about 1000 ° C. without degrading the gate insulating film 16. Also prevents the gate leakage current from increasing or film peeling from occurring on the surface of the gate insulating film. As described above, the semiconductor substrate is formed in the chamber in which the titanium nitride film 13 is formed. With 10 being continuously held, the inside of the chamber is changed to an NH ₃ atmosphere and the temperature inside the chamber is maintained at a temperature equal to or higher than the film formation temperature of the titanium nitride film 13.

As described above, when the titanium nitride film 13 is kept at a temperature higher than the film forming temperature in the atmosphere of NH ₃ ,
As shown in FIG. 4, unreacted TiCl ₄ and NH ₃ present in the titanium nitride film 13 react with each other to generate HCl, and the generated HCl evaporates.
Residual chlorine in 3 is reduced.

FIG. 5 shows the relationship between the depth from the surface of the titanium nitride film 13 and the chlorine concentration in the nitride film 13 measured using XPS. In FIG. 5, the broken line shows the first embodiment (when the titanium nitride film 13 formed at 490 ° C. is not heat-treated), and the solid line shows the second embodiment (formed at 490 ° C.). The case where the titanium nitride film 13 is heat-treated in an ammonia atmosphere) is shown.

As can be seen from FIG. 5, when the titanium nitride film 13 is heat-treated in an ammonia atmosphere as in the second embodiment, the chlorine concentration in the titanium nitride film 13 becomes 2%.
It can be greatly reduced to about at%.

Therefore, according to the second embodiment, in addition to the effects obtained by the first embodiment, residual chlorine in the titanium nitride film 13 is reduced to reduce the gate leak current and the surface of the gate insulating film. It is possible to prevent peeling of the film.

According to the second embodiment, the titanium nitride film 13 and the residual chlorine can be removed by using the same chamber and changing the gas introduced into the chamber. The residual chlorine can be removed while suppressing the increase in the process.

In the second embodiment, TiCl _{4 is used} as a source gas for forming the titanium nitride film 13.
A mixed gas of NH ₃ and NH ₃ was used, but instead of this, Ti
The titanium nitride film 13 may be formed using a mixed gas of I ₄ and NH ₃ or a mixed gas of TiBr ₄ and NH ₃ .
Also in this case, by keeping the titanium nitride film 13 at a temperature equal to or higher than the film forming temperature in the atmosphere of NH ₃ , iodine (I) or bromine (B) remaining in the titanium nitride film 13 is retained.
r) can be reduced.

(Third Embodiment) As a third embodiment of the present invention, a method of manufacturing a semiconductor device having an n-type MOSFET will be described below with reference to FIGS.

First, as shown in FIG. 1A, similarly to the first embodiment, after the element isolation region 11 is formed on the surface portion of the semiconductor substrate 10 made of, for example, a p-type silicon substrate, the semiconductor substrate is formed. A silicon oxynitride film 12 having a thickness of about 2 nm to be a gate insulating film is formed on 10.

Next, at a temperature of about 490 ° C., Ti
By a CVD method using a mixed gas of Cl ₄ and NH ₃ as a source gas, 10 is formed on the silicon oxynitride film 12.
A titanium nitride film 13 having a thickness of about nm is formed.
Then, the titanium nitride film 13 is subjected to a rapid heat treatment for about 10 to 60 seconds at a temperature of 600 to 900 ° C. in an atmosphere of NH ₃ .

Next, in the same manner as in the first embodiment, the titanium nitride film 13 is sputtered on the titanium nitride film 13 by sputtering.
After forming the tungsten film 14 having a thickness of about nm, as shown in FIG. 1B, a laminated film of the tungsten film 14 and the titanium nitride film 13 and the silicon oxynitride film 1 are formed.
2 is patterned to form a gate electrode 15 and a gate insulating film 16.

Next, similarly to the first embodiment, after forming the sidewall 17 on the side surface of the gate electrode 15 and forming the impurity diffusion layer 18 to be the source region or the drain region in the semiconductor substrate 10, As shown in FIG. 1C, the interlayer insulating film 19, the contact 20, and the wiring layer 2
1 is formed.

As in the third embodiment, the titanium nitride film 1
When 3 is subjected to the rapid heat treatment in the atmosphere of NH ₃ , Cl existing in the titanium nitride film 13 is evaporated as shown in FIG. 6, so that the residual chlorine in the titanium nitride film 13 is reduced. Further, since the heat treatment is performed in the atmosphere of NH ₃ , the unreacted TiCl ₄ and NH ₃ existing in the titanium nitride film 13 react with each other, as in the second embodiment.
A phenomenon occurs in which Cl is generated and the generated HCl evaporates.

Therefore, according to the third embodiment, in addition to the effects obtained by the first embodiment, residual chlorine in the titanium nitride film 13 is reduced to reduce the gate leak current and the surface of the gate insulating film. It is possible to prevent peeling of the film.

Further, according to the third embodiment, since the residual chlorine is evaporated by the rapid heat treatment, the semiconductor substrate 10
Since the heat treatment is not performed for a long time, the semiconductor element can be prevented from being damaged by the heat treatment.

In the third embodiment, the rapid heat treatment is performed in an ammonia gas atmosphere, but instead of this, a nitrogen gas atmosphere, a mixed gas atmosphere of nitrogen gas and hydrogen gas, an argon gas atmosphere or The rapid heat treatment may be performed in vacuum.

In the third embodiment, TiCl 2 is used as the source gas for forming the titanium nitride film 13.
A mixed gas of ₄ and NH ₃ was used, but instead of this, Ti
The titanium nitride film 13 may be formed using a mixed gas of I ₄ and NH ₃ or a mixed gas of TiBr ₄ and NH ₃ .
Also in this case, the rapid heat treatment of the titanium nitride film 13 can reduce the residual iodine or bromine in the titanium nitride film 13.

(Fourth Embodiment) As a fourth embodiment of the present invention, a method of manufacturing a semiconductor device having an n-type MOSFET will be described below with reference to FIGS.

First, as shown in FIG. 1A, the element isolation region 11 is formed on the surface portion of the semiconductor substrate 10 made of, for example, a p-type silicon substrate as in the first embodiment, and then the semiconductor substrate is formed. A silicon oxynitride film 12 having a thickness of about 2 nm to be a gate insulating film is formed on 10.

Next, at a temperature of about 650 ° C., T
1 is formed on the silicon oxynitride film 12 by the CVD method using a mixed gas of iCl ₄ and NH ₃ as a source gas.
A titanium nitride film 13 having a thickness of about 0 nm is formed.

Next, in the same manner as in the first embodiment, the titanium nitride film 13 is deposited on the titanium nitride film 13 by the sputtering method.
After forming the tungsten film 14 having a thickness of about nm, as shown in FIG. 1B, a laminated film of the tungsten film 14 and the titanium nitride film 13 and the silicon oxynitride film 1 are formed.
2 is patterned to form a gate electrode 15 and a gate insulating film 16.

Next, similarly to the first embodiment, after forming the sidewall 17 on the side surface of the gate electrode 15 and forming the impurity diffusion layer 18 to be the source region or the drain region in the semiconductor substrate 10, As shown in FIG. 1C, the interlayer insulating film 19, the contact 20, and the wiring layer 2
1 is formed.

Since the titanium nitride film is formed at a high temperature as in the fourth embodiment, the concentration of residual chlorine in the titanium nitride film can be reduced.

FIG. 7 shows the relationship between the depth from the surface of the titanium nitride film 13 and the chlorine concentration in the nitride film 13 measured using XPS. In FIG. 7, the broken line shows the first embodiment (when the titanium nitride film 13 formed at 490 ° C. is not subjected to heat treatment), and the solid line shows the fourth embodiment (formed at 650 ° C.). The case where no heat treatment is applied to the titanium nitride film 13 is shown. Note that, in FIG. 7, the portion indicated by the alternate long and short dash line is due to contamination on the surface of the titanium nitride film 13, and the portion indicated by the alternate long and two short dashes line is a measurement error.

As can be seen from FIG. 7, when the titanium nitride film 13 is formed at a temperature of 650 ° C. as in the fourth embodiment, the chlorine concentration in the titanium nitride film 13 is greatly reduced to about 2 at%. be able to.

FIG. 8 shows the relationship between the film formation temperature of the titanium nitride film 13 and the chlorine concentration in the film. In FIG.
Indicates the chlorine concentration in the film before the heat treatment, and ● indicates the chlorine concentration in the film after the heat treatment for 30 seconds at a temperature of 1000 ° C. It can be seen from FIG. 8 that the chlorine concentration in the film before and after the heat treatment becomes lower as the film forming temperature becomes higher.

FIG. 9 shows that a film forming temperature (first temperature) of 650 ° C. is formed on the gate insulating film 16 having a thickness of 3.5 nm by a CVD method using a source gas composed of a mixed gas of TiCl ₄ and NH ₃ . No. 4 embodiment) and a film forming temperature of 490 ° C. (first
2) shows the residual chlorine concentration of the titanium nitride film 13 formed in Embodiment 1) and the gate leakage current value of the MOS capacitor when the titanium nitride film 13 is heat-treated at a temperature of 1000 ° C. for 10 seconds. ing.

It can be seen from FIG. 9 that as the film forming temperature becomes higher, the amount of residual chlorine after the heat treatment becomes smaller, which causes the gate leakage current to decrease. From this, it is understood that according to the fourth embodiment, the gate leak current can be suppressed even if the heat treatment at about 1000 ° C. for activating the impurity diffusion layer 18 to be the source region or the drain region is performed.

FIG. 10 shows that a film formation temperature (first temperature) of 650 ° C. is formed on the gate insulating film 16 having a thickness of 2.4 nm by a CVD method using a source gas composed of a mixed gas of TiCl ₄ and NH ₃ . 4 embodiment) and the temperature of heat treatment performed on the titanium nitride film 13 formed at the film forming temperature of 490 ° C. (first embodiment) and the gate leakage current value of the MOS capacitor. There is.

From FIG. 10, it is understood that according to the fourth embodiment, the gate leak current hardly changes even when the titanium nitride film 13 is heat-treated.

According to the fourth embodiment, in addition to the effects obtained by the first embodiment, the residual chlorine in the titanium nitride film 13 is reduced to reduce the gate leak current and the surface of the gate insulating film. It is possible to prevent film peeling.

Further, according to the fourth embodiment, since the titanium nitride film 13 is formed at a high temperature, the film formation rate is higher than that at a low temperature. Therefore, the titanium nitride film 13 having a small film thickness is formed. Although difficult to form, it is possible to form the titanium nitride film 13 having a thickness of about 20 nm.

In the fourth embodiment, TiCl _{4 is used} as the source gas for forming the titanium nitride film 13.
A mixed gas of NH ₃ and NH ₃ was used, but instead of this, Ti
The titanium nitride film 13 may be formed using a mixed gas of I ₄ and NH ₃ or a mixed gas of TiBr ₄ and NH ₃ .
Also in this case, the residual iodine or bromine in the titanium nitride film 13 can be reduced.

(Fifth Embodiment) Hereinafter, as a fifth embodiment of the present invention, a method of manufacturing a semiconductor device having an n-type MOSFET and a capacitor will be described with reference to FIGS.
This will be described with reference to (c) and FIGS. 12 (a) to 12 (c).

First, as shown in FIG. 11A, an element isolation region 31 is formed on the surface portion of a semiconductor substrate 30 made of, for example, a p-type silicon substrate by a known method, and then the semiconductor substrate 30 is provided with an area of about 2 nm. Forming a silicon oxynitride film 32 having a thickness of 1 to serve as a gate insulating film.

Next, TiCl ₄ and NH ₃ are used as source gases, and a CVD method is performed at a film forming temperature of about 490 ° C. to form a film on the silicon nitride oxide film 32.
After forming a titanium nitride film 33 having a thickness of about 10 to 20 nm and serving as a lower gate electrode and a capacitor lower electrode,
A silicon oxide film 34 having a thickness of about 5 to 10 nm and serving as a capacitance insulating film is formed on the titanium nitride film 33.

Next, as shown in FIG. 11B, after forming a first resist pattern 35 on the silicon oxide film 34, the silicon oxide film 34 is masked with the first resist pattern 35. For example, etching is performed using a dilute hydrofluoric acid solution to form the capacitance insulating film 34B made of the silicon oxide film 34.

Next, as shown in FIG. 11C, after removing the first resist pattern 35, a thickness of about 100 nm is formed on the titanium nitride film 33 and the capacitor insulating film 34B by a sputtering method. After forming the tungsten film 36 which has the upper gate electrode and the capacitor upper electrode, a silicon nitride film 37 having a thickness of about 100 nm and serving as a hard mask is formed on the tungsten film 36. .

Next, as shown in FIG. 12A, after forming a second resist pattern 38 on the silicon nitride film 37, the second resist pattern 38 is used as a mask for the silicon nitride film 37. Figure 1 after etching
As shown in FIG. 2B, a hard mask 37A made of the silicon nitride film 37 is formed.

Next, after removing the second resist pattern 38, the tungsten film 36, the titanium nitride film 33 and the silicon oxynitride film 32 are patterned using a hard mask 37A to form an upper layer of the tungsten film 36. Gate electrode 36A and capacitor upper electrode 36B, lower gate electrode 33A and capacitor lower electrode 33B made of titanium nitride film 33, and gate insulating film 32A made of silicon oxynitride film 32 and patterned insulating film 32B.
To form. Thereby, the gate electrode 39 composed of the upper-layer gate electrode 36A and the lower-layer gate electrode 33A,
A capacitance element 40 including the capacitance upper electrode 36B, the capacitance insulating film 34B, and the capacitance lower electrode 36B is formed.

Next, as shown in FIG. 12C, a sidewall 41 is formed on the side surfaces of the gate electrode 39 and the capacitor 40 by a known method, and the semiconductor substrate 30 is formed.
Then, an impurity diffusion layer 42 to be a source or a drain is formed.

Next, after forming an interlayer insulating film 43 over the entire surface of the gate electrode 39 and the capacitor 40, a contact hole is formed in the interlayer insulating film 43. Next, after depositing a metal film on the interlayer insulating film 43 so as to fill the contact hole, the metal film is patterned to form a contact and a metal wiring 44.

Therefore, according to the fifth embodiment, the tungsten film 36 to be the upper gate electrode 36A is patterned to form the capacitor upper electrode 36B, and the titanium nitride film 33 to be the lower gate electrode 33A is patterned. Since the capacitor lower electrode 33B is formed by using the capacitor lower electrode 33B, in addition to the effects obtained by the first embodiment, it is possible to obtain the effect that the capacitor element can be formed without increasing the number of steps.

Further, since the capacitive upper electrode 36B is made of the tungsten film 36 and the capacitive lower electrode 33B is made of the titanium nitride film 33, the manufacturing process is performed like an electrode made of a polycrystalline silicon film into which conductive impurities are introduced. Variations in the characteristics of the electrodes and deterioration of the high-frequency characteristics caused by the heat treatment inside do not occur. That is, according to the sixth embodiment, not only the number of processes can be reduced, but also the characteristics of the capacitive element can be improved.

(Sixth Embodiment) Hereinafter, as a sixth embodiment of the present invention, a method for manufacturing a semiconductor device having an n-type MOSFET and a resistor will be described with reference to FIGS.
(C), FIG. 14 (a) to (c), FIG. 15 (a), (b)
16 (a) to 16 (c).

First, as shown in FIG. 13A, an element isolation region 51 is formed on the surface of a semiconductor substrate 50 made of, for example, a p-type silicon substrate by a known method, and then the semiconductor substrate 50 is formed to have a thickness of about 2 nm. Forming a silicon oxynitride film 52 which has a thickness of and serves as a gate insulating film.

Next, TiCl ₄ and NH ₃ are used as source gases, and a CVD method is performed at a film forming temperature of about 490 ° C. to form a film on the silicon nitride oxide film 52.
After forming a titanium nitride film 53 having a thickness of about 10 to 20 nm and serving as a lower gate electrode and a resistor, a resistor having a thickness of about 20 to 50 nm is formed on the titanium nitride film 53. A silicon oxide film 54 to be a first hard mask 54A (see FIG. 13B) for forming a body is formed. As shown in FIG. 16A, the silicon oxide film 5
The thickness t ₁ of the element 4 is set to be substantially equal to the height t ₂ of the element isolation region 51 protruding from the semiconductor substrate 50. The reason for doing this will be described later.

Next, as shown in FIG. 13B, after forming a first resist pattern 55 on the silicon oxide film 54, the first resist pattern 55 is used as a mask for the silicon oxide film 54. For example, etching is performed using a dilute hydrofluoric acid solution to form the first hard mask 54A made of the silicon oxide film 54.

Next, after removing the first resist pattern 55, as shown in FIG. 13C, the titanium nitride film 53 and the first hard mask 54 are formed by the sputtering method.
After forming a tungsten film 56 having a thickness of about 100 nm on A as the upper gate electrode, a gate electrode having a thickness of about 100 nm is formed on the tungsten film 56. Then, a silicon nitride film 57 is formed which serves as a second hard mask.

Next, as shown in FIG. 14A, after forming a second resist pattern 58 on the silicon nitride film 57, the second resist pattern 58 is used as a mask for the silicon nitride film 57. Figure 1 after etching
As shown in FIG. 4B, the second hard mask 57A made of the silicon nitride film 57 is formed. At this time, FIG.
As shown in (b), an etching gas having selectivity with respect to the tungsten film 56, such as CHF ₃ and O _2, is used so that an etching residue 64 made of the silicon nitride film 57 does not occur in the step portion of the tungsten film 56. It is preferable to use an etching gas whose main component is the mixed gas of and to perform sufficient over-etching.

Next, after removing the second resist pattern 58, the tungsten film 56 is etched with an etching gas containing a chlorine-based gas using the second hard mask 57A, as shown in FIG. As shown in c), the upper gate electrode 56 made of the tungsten film 56.
Form A. In this etching step, the first hard mask 54A made of the silicon oxide film 54 is exposed, but since the etching selectivity of the tungsten film 56 with respect to the silicon oxide film 54 is high, the first hard mask 54A may not disappear. Absent.

As described above, since the thickness t ₁ of the silicon oxide film 54 is almost equal to the height t _{2 of the} step portion where the element isolation region 51 projects from the semiconductor substrate 50, the thickness t ₁ of FIG.
As shown in (c), the thickness of the first tungsten film 65a remaining on the side surface of the first hard mask 54A on the titanium nitride film 53 and the step portion of the element isolation region 51 on the titanium nitride film 53. The thickness of the second tungsten film 65b remaining in the region corresponding to is approximately equal. Therefore, the first tungsten film 65a is removed by overetching to completely remove the second tungsten film 65b. The thickness t ₁ of the silicon oxide film 54 may be equal to or less than the height t _{2 of the} step portion where the element isolation region 51 projects from the semiconductor substrate 50.

Next, the titanium nitride film 53 and the silicon oxynitride film 52 are patterned by using the first hard mask 54A and the second hard mask 57A, as shown in FIG. , Titanium nitride film 53
A lower gate electrode 53A and a resistor 53B are formed, and a gate insulating film 52A made of a silicon oxynitride film 52 and a patterned insulating film 52B are formed.

Next, as shown in FIG. 15B, a sidewall 60 is formed on the side surface of the gate electrode 59 composed of the upper gate electrode 56A and the lower gate electrode 53A by a known method, and the semiconductor substrate is formed. An impurity diffusion layer 61 serving as a source or a drain is formed in 50.

Next, after forming an interlayer insulating film 62 over the entire surface of the gate electrode 59 and the resistor 53B, a contact hole is formed in the interlayer insulating film 62. Next, after depositing a metal film on the interlayer insulating film 62 so as to fill the contact hole, the metal film is patterned to form a contact and a metal wiring 63.

Therefore, according to the sixth embodiment, the titanium nitride film 53 to be the lower gate electrode 53A is patterned to form the resistor 53B. Therefore, in addition to the effects obtained by the first embodiment, It is also possible to obtain the effect that the resistor 53B can be formed without increasing the number of steps.

By the way, the titanium nitride film 53 to be the resistor 53B, which is a conductor, is 150 to 250 μΩ · cm.
Since the resistivity is high and the film thickness is as thin as 10 to 20 nm, a sufficiently high sheet resistance value of about 200Ω / □ can be realized.

The resistor 53B is the titanium nitride film 53.
Therefore, unlike the resistor made of a polycrystalline silicon film into which conductive impurities are introduced, the characteristic variations of the resistor and the deterioration of the high frequency characteristic caused by the heat treatment during the manufacturing process do not occur. That is, according to the sixth embodiment, not only the number of processes can be reduced but also the characteristics of the resistor 53B can be improved.

[0115]

According to the method of manufacturing a semiconductor device of the present invention, since the titanium nitride film is formed by the CVD method on the insulating film to be the gate insulating film, the insulating film is not physically damaged. Therefore, the reliability of the gate insulating film made of the insulating film is improved. Therefore, M of high performance and high reliability
OSFETs can be manufactured.

According to the first semiconductor device of the present invention,
A semiconductor device including a highly reliable gate electrode and a capacitor with less variation in electrode characteristics and less deterioration in high-frequency characteristics can be realized.

According to the second semiconductor device of the present invention,
It is possible to realize a semiconductor device including a highly reliable gate electrode and a resistor having a high sheet resistance value.

[Brief description of drawings]

1A to 1C are cross-sectional views showing respective steps of a method for manufacturing a semiconductor device according to first to fourth embodiments.

FIG. 2 (a) is a cross-sectional view showing a crystal structure of a tungsten film formed on a titanium nitride film by a CVD method, and FIG. 2 (b) is a film formed on a titanium nitride film by a sputtering method. FIG. 4 is a cross-sectional view showing a crystal structure of a tungsten film.

FIG. 3 is a cross-sectional view illustrating a problem when a heat treatment at about 1000 ° C. is performed on a laminated film of a lower titanium nitride film and an upper tungsten film.

FIG. 4 is a cross-sectional view illustrating an effect of the method for manufacturing a semiconductor device according to the second embodiment.

FIG. 5 is a diagram showing the relationship between the depth from the surface of the titanium nitride film obtained by the first and second embodiments and the chlorine concentration in the titanium nitride film.

FIG. 6 is a cross-sectional view illustrating an effect of the method for manufacturing a semiconductor device according to the third embodiment.

FIG. 7 is a diagram showing the relationship between the depth from the surface of the titanium nitride film obtained by the first and fourth embodiments and the chlorine concentration in the titanium nitride film.

FIG. 8 is a diagram showing the relationship between the film formation temperature of a titanium nitride film and the chlorine concentration in the film in the fourth embodiment.

FIG. 9 is a diagram showing a residual chlorine concentration in a titanium nitride film obtained by the first and fourth embodiments and a gate leak current value of a MOS capacitor when the titanium nitride film is heat-treated. Is.

FIG. 10 is a diagram showing the relationship between the temperature of the heat treatment for the titanium nitride film obtained in the first and fourth embodiments and the gate leakage current value of the MOS capacitor.

11A to 11C are cross-sectional views showing each step of the method of manufacturing a semiconductor device according to the fifth embodiment.

12A to 12C are cross-sectional views showing each step of the method for manufacturing a semiconductor device according to the fifth embodiment.

13A to 13C are cross-sectional views showing each step of the method for manufacturing a semiconductor device according to the sixth embodiment.

14A to 14C are cross-sectional views showing each step of the method for manufacturing a semiconductor device according to the sixth embodiment.

15A and 15B are cross-sectional views showing each step of the method for manufacturing a semiconductor device according to the sixth embodiment.

16A to 16C are cross-sectional views illustrating points to be noted in each step of the method for manufacturing a semiconductor device according to the sixth embodiment.

[Explanation of symbols]

10 Semiconductor substrate 11 Element isolation region 12 Silicon oxynitride film 13 Titanium nitride film 14 Tungsten film 15 Gate electrode 16 Gate insulating film 17 Sidewall 18 Impurity diffusion layer 19 Interlayer insulation film 20 contacts 21 wiring layer 30 Semiconductor substrate 31 element isolation region 32 Silicon oxynitride film 32A gate insulating film 32B patterned insulating film 33 Titanium nitride film 33A Lower layer gate electrode 33B Capacitance lower electrode 34 Silicon oxide film 34B Capacitance insulating film 35 First resist pattern 36 Tungsten film 36A Upper layer gate electrode 36B capacitance upper electrode 37 Silicon nitride film 37A hard mask 38 Second resist pattern 39 Gate electrode 40 capacitive element 41 Sidewall 42 Impurity diffusion layer 43 Interlayer insulation film 44 Metal wiring 50 Semiconductor substrate 51 element isolation region 52 Silicon oxynitride film 52A Gate insulation film 52B patterned insulating film 53 Titanium nitride film 53A Lower layer gate electrode 53B resistor 54 Silicon oxide film 54A First hard mask 55 First resist pattern 56 Tungsten film 56A Upper layer gate electrode 57 Silicon nitride film 57A Second hard mask 58 Second resist pattern 59 Gate electrode 60 sidewall 61 Impurity diffusion layer 62 Interlayer insulation film 63 Metal wiring 64 Etching remaining 65a First tungsten film 65b Second tungsten film

Continuation of front page (51) Int.Cl. ⁷ Identification code FI H01L 27/04 H01L 27/06 102A 27/06 29/62 G 29/43 29/78 301G 29/78 (56) References JP 2001- 203276 (JP, A) JP 2000-349285 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/28

Claims (10)

(57) [Claims] 1. A first gate insulating film formed on a semiconductor substrate.
Forming an insulating film, and forming a nitrided titanium film on the first insulating film by chemical vapor deposition.
And a tongue film formed on the titanium nitride film by a sputtering method.
A step of forming a stainless steel film, and a laminated film including the tungsten film and the titanium nitride film.
Pattern to form a gate electrode composed of the above-mentioned laminated film.
And a step of forming, a step of depositing said titanium nitride film, a method of manufacturing a semiconductor device which comprises a step of performing heat treatment in an ammonia atmosphere to the titanium nitride film. 2. A step of performing heat treatment on the titanium nitride film, 請 characterized in that it is performed in the titanium nitride film is formed chambers within the same chamber and
The method for manufacturing a semiconductor device according to claim 1 . 3. A first gate insulating film formed on a semiconductor substrate.
Forming an insulating film, and forming a nitrided titanium film on the first insulating film by chemical vapor deposition.
And a tongue film formed on the titanium nitride film by a sputtering method.
A step of forming a stainless steel film, and a laminated film including the tungsten film and the titanium nitride film.
Pattern to form a gate electrode composed of the above-mentioned laminated film.
And a step of forming, a step of depositing said titanium nitride film, a semiconductor device which comprises a step of performing heat treatment at a deposition temperature higher than the temperature of the titanium nitride film with respect to the titanium nitride film Manufacturing method. 4. The method of manufacturing a semiconductor device according to claim 3 , wherein the heat treatment is performed in an ammonia atmosphere. 5. A first gate insulating film formed on a semiconductor substrate.
The insulating film and as factories to form the said titanium nitride by chemical vapor deposition on the first insulating film
And a tongue film formed on the titanium nitride film by a sputtering method.
A step of forming a stainless steel film, and a laminated film including the tungsten film and the titanium nitride film.
Pattern to form a gate electrode composed of the above-mentioned laminated film.
And a step of forming, a step of depositing said titanium nitride film, a method of manufacturing a semiconductor device characterized by carried out at a temperature of more than 600 ° C.. 6. A first gate insulating film formed on a semiconductor substrate.
Forming an insulating film, and forming a nitrided titanium film on the first insulating film by chemical vapor deposition.
And a tongue film formed on the titanium nitride film by a sputtering method.
A step of forming a stainless steel film, and a laminated film including the tungsten film and the titanium nitride film.
Pattern to form a gate electrode composed of the above-mentioned laminated film.
A second step on the titanium nitride film between the step of forming, the step of forming the titanium nitride film and the step of forming the tungsten film.
After forming an insulating film, said second insulating film is patterned and a step of forming a capacitor insulating film, the step of forming the gate electrode by patterning the laminated film is composed of the tungsten film A method of manufacturing a semiconductor device, comprising: forming a capacitor upper electrode and forming a capacitor lower electrode made of the titanium nitride film. 7. A semiconductor substrate on which an element isolation region is formed.
A step of forming a first insulating film to be a gate insulating film on the first insulating film, and a titanium nitride film on the first insulating film by chemical vapor deposition.
And a tongue film formed on the titanium nitride film by a sputtering method.
A step of forming a stainless steel film, and a laminated film including the tungsten film and the titanium nitride film.
Pattern to form a gate electrode composed of the above-mentioned laminated film.
A second step on the titanium nitride film between the step of forming, the step of forming the titanium nitride film and the step of forming the tungsten film.
After forming the insulating film, patterning the second insulating film, and forming a hard mask composed of the second insulating film on the element isolation region, by patterning the stacked film The method of manufacturing a semiconductor device, wherein the step of forming the gate electrode by using the hard mask includes patterning the titanium nitride film to form a resistor made of the titanium nitride film. 8. The manufacturing of a semiconductor device according to claim 7 , wherein the thickness of the second insulating film is equal to or less than the height of the element isolation region protruding from the semiconductor substrate. Method. 9. A gate insulation formed on a semiconductor substrate.
Film, a lower gate electrode made of a titanium nitride film formed on the gate insulating film by a chemical vapor deposition method, and an upper layer made of a tungsten film formed on the titanium nitride film by a sputtering method. A stacked gate electrode composed of a gate electrode of, a capacitor lower electrode composed of the titanium nitride film, a capacitor insulating film formed on the capacitor lower electrode, and the capacitor insulating film formed on the capacitor insulating film. A semiconductor device comprising: a capacitive element composed of a capacitive upper electrode made of a tungsten film. 10. A gate insulator formed on a semiconductor substrate.
An edge film, a lower gate electrode made of a titanium nitride film formed on the gate insulating film by a chemical vapor deposition method, and a tungsten film formed on the titanium nitride film by a sputtering method. A semiconductor device comprising: a stacked gate electrode including an upper gate electrode; and a resistor including the titanium nitride film.