JPH1022396A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a PMOSFET having a p-type Si gate and good MOS characteristics by suppressing the break-through diffusion phenomenon of B due to a silicon nitride film in manufacturing surface channel CMOS transistors. SOLUTION: A gate insulation film 2 is formed on the surface of an Si substrate 1, an Si film 3 is formed on this film 2, a silicon nitride film 5 is deposited on the Si film 3, B is added into a portion of the nitride film 5 deposited on a p-type gate forming region of the Si film 3, and the substrate 1 is heat treated at temps. high enough to bond B in the nitride film 5 with H.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a penetration diffusion phenomenon of boron caused by a silicon nitride film in manufacturing a surface channel type CMOSFET (complementary insulated gate field effect transistor). Regarding the method of suppressing.

[0002]

2. Description of the Related Art Conventionally, when realizing a MOSFET having a fine structure with a gate length of 0.5 μm or less, an N-channel MOSFE
Not only T (NMOSFET) but also P-channel MOSF
Surface channel MOSFE for ET (PMOSFET)
A structure using T has been proposed. When realizing this structure, the PMOSFET gate electrode must be
Boron or a boron compound, which is a type impurity, is introduced into the gate electrode.

FIGS. 3A to 3D show an example of a method of manufacturing a surface channel type PMOSFET which has been conventionally proposed. First, after a well region and an element isolation insulating film region 31 are formed on the surface of a semiconductor substrate 30, a predetermined gate insulating film 32 is formed. Thereafter, a silicon film 33 is deposited, and the silicon film is selectively removed through a lithography process to form a gate electrode 33a.

Next, using the silicon film 33a and the element isolation insulating film 31 as masks, an N-type impurity and a P-type impurity are respectively doped through a lithography process to form a shallow diffusion layer 36 used as a source / drain.

Thereafter, a silicon nitride film 35 is deposited by a low pressure CVD (chemical vapor deposition) method using, for example, a mixed gas of ammonia and dichlorosilane, and anisotropic etching is performed to form a gate sidewall 35a.

[0006] Then, using a lithography process, N
An N-type impurity is added to a region to be a MOSFET,
By implanting a P-type impurity into the ET region by ion implantation, the gate electrode and the source / drain region 37 are simultaneously doped with the impurity and heat-treated to activate the impurity.

After removing the oxide film on the substrate and the gate silicon film, a so-called salicide process for forming a refractory metal silicide on the gate and the diffusion layer region in a self-aligned manner is performed. A process is performed to form a semiconductor element.

By the way, as described above, dichlorosilane and ammonia gas are mixed under reduced pressure to form a silicon nitride film 3.
When the film 5 is formed, a large amount of hydrogen is generated, and hydrogen is taken into the silicon nitride film 35.

FIG. 4 shows the boron diffusion acceleration characteristic by H ₂ . That is, under the conditions of the thickness Tox of the silicon oxide film 32 under the silicon film 33a = 10 nm, the dose amount of doped boron = 5 × 10 ¹⁵ cm ⁻² , and the annealing for 60 minutes, a forming gas containing, for example, 10% of H _2. (F
G) shows the boron profile in the silicon substrate 30 under the silicon oxide film 32 with the annealing temperature as a parameter in N ₂ gas. FIG. 4 shows that hydrogen accelerates the diffusion of boron in the silicon oxide film.

FIG. 5 shows the boron diffusion acceleration characteristic of the silicon nitride film 35. That is, LP on the silicon film
When a silicon nitride film is provided by a CVD method, when a cap insulating film is not provided on a silicon film, and when a silicon oxide film is provided on a silicon film by a CVD method, the thickness of a silicon oxide film below a silicon film Tox = 10n
m, dose of doped boron = 5 × 10 ¹⁵ cm ⁻² ,
7 shows a boron profile in a silicon substrate under a silicon oxide film under the conditions of annealing at 900 ° C. for 60 minutes. FIG. 5 shows that when a silicon nitride film is formed on the silicon film by the LPCVD method, the diffusion of boron becomes faster.

Therefore, the silicon film 3 for the gate electrode
When boron introduced as a P-type impurity in 3a reaches the gate silicon oxide film interface, a so-called "boron penetration diffusion phenomenon" occurs in which boron diffuses through the gate oxide film 32 into the channel region.

[0012] When the above-described boron penetration diffusion occurs, adverse effects such as fluctuation of the threshold value of the MOSFET and deterioration of the cut-off characteristic are caused. Also, the gate oxide film 3
There is also a report that if boron is present in a high concentration in 2, the reliability is deteriorated.

As described above, if the thermal process is performed after the silicon nitride film 35 is deposited on the P-type silicon film, the phenomenon of the boron penetration and diffusion easily occurs, so that the thermal process is restricted.

It is also known that even if boron is doped into a silicon film after a silicon nitride film is formed, boron easily penetrates and diffuses in a subsequent thermal process.

It is known that this penetration diffusion phenomenon is suppressed when the oxynitride film is used as a gate insulating film, and it is known that penetration diffusion is less likely to occur as the nitrogen concentration is higher. The heat process for nitriding becomes longer, causing adverse effects such as changing the channel profile.

As a method for desorbing hydrogen generated during the formation of the silicon nitride film, a high-temperature heat treatment may be performed. However, boron introduced into the silicon film in the high-temperature heat process causes penetration and diffusion. Would

[0017]

As described above, the conventional method of manufacturing a semiconductor device uses a surface channel type CMOSF.
In the manufacture of ET, there is a problem in that a boron penetration diffusion phenomenon caused by the silicon nitride film occurs, causing problems such as a change in the threshold value of the MOSFET and a deterioration in cutoff characteristics. In addition, there is a problem that reliability is deteriorated when boron is present in a high concentration in the gate oxide film.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. In manufacturing a surface-channel type CMOSFET, the present invention suppresses the penetration diffusion phenomenon of boron caused by a silicon nitride film and provides a P-type semiconductor device having excellent MOS characteristics. It is an object of the present invention to provide a method for manufacturing a semiconductor device capable of realizing a PMOSFET having a silicon gate.

[0019]

According to the present invention, there is provided a method of manufacturing a semiconductor device, comprising the steps of: forming a gate insulating film on a surface of a semiconductor substrate; forming a silicon film on the gate insulating film; Depositing a silicon nitride film on the silicon substrate; adding boron to at least a silicon nitride film of the silicon nitride film deposited on a P-type gate formation planned region of the silicon film; Performing a heat treatment at a temperature at which boron and hydrogen in the silicon nitride film are bonded to each other.

Further, a method of manufacturing a semiconductor device according to the present invention
Forming a gate insulating film on the surface of the semiconductor substrate, forming a silicon film on the gate insulating film, selectively removing the silicon film to form a gate electrode; Depositing a silicon nitride film for forming a gate sidewall, adding boron to the silicon nitride film, and performing a heat treatment on the semiconductor substrate at a temperature at which boron and hydrogen in the silicon nitride film are bonded. And characterized in that:

Further, the method of manufacturing a semiconductor device according to the present invention
Forming a gate insulating film on the surface of the silicon substrate, forming a silicon film on the gate insulating film, forming a gate electrode by selectively removing the silicon film, Depositing a silicon nitride film for forming a gate sidewall, forming the gate sidewall by processing the silicon film by anisotropic etching, and adding boron simultaneously in the silicon nitride film and the silicon substrate. And a step of subjecting the silicon substrate to a heat treatment at a temperature at which boron and hydrogen in the silicon nitride film are combined.

Further, a method of manufacturing a semiconductor device according to the present invention
Forming a gate insulating film on the surface of the semiconductor substrate; forming a silicon film on the gate insulating film; depositing a silicon nitride film on the silicon film; A step of adding nitrogen to a silicon nitride film deposited on a region where a P-type gate is to be formed in the silicon film; and a step of performing a heat treatment on the semiconductor substrate at a temperature at which nitrogen and hydrogen in the silicon nitride film are combined. It is characterized by having.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 (a) to 1 (d)
1 shows a first embodiment according to a method for manufacturing a semiconductor device of the present invention.

In the method of manufacturing a semiconductor device according to the first embodiment, a step of forming a gate insulating film on a surface of a semiconductor substrate, a step of forming a silicon film on the gate insulating film, and selecting the silicon film Removing the gate electrode, forming a silicon nitride film for forming a gate sidewall on the silicon film, adding boron into the silicon nitride film, and removing the semiconductor substrate. Performing a heat treatment at a temperature at which boron and hydrogen in the silicon nitride film are bonded to each other.

(Embodiment 1) First, as shown in FIG. 1A, an element isolation insulating film 4 is formed on a P-type semiconductor substrate 1 by LOCOS (selective oxidation) method. A 6-nm-thick gate insulating film 2 is formed by an oxidation method.
Thereafter, a silicon film 3 is deposited to a thickness of 200 nm.

Next, as shown in FIG. 1 (b), processing the gate electrode 3a through the lithography process, further through the lithography process, As + NMOS region, a PMOS region, respectively, by introducing BF ₂ +, A shallow source / drain diffusion layer 6 is obtained.

Next, as shown in FIG. 1C, an LP (reduced pressure) obtained by mixing ammonia gas and dichlorosilane gas is used.
The silicon nitride film 5 for the gate side wall is
Deposit 00 nm.

Thereafter, boron B is ion-implanted.
+ At an acceleration voltage of ¹⁵ keV and a dose of 1 × 10 ¹⁵ (atoms /
cm ³ ) and doping in a nitrogen atmosphere at 650 ° C.
Heat treatment for a minute. In order to combine hydrogen desorbed in the silicon nitride film 5 with boron and desorb it, it is efficient to perform heat treatment at 600 ° C. or higher.

Next, as shown in FIG. 1D, the silicon nitride film 5 is processed using an anisotropic etching technique to form a gate side wall 5a. Then, after doping the source / drain region 7 and the gate electrode 3a (silicon film) with impurities, annealing is performed for 60 minutes in a nitrogen atmosphere at 850 ° C. to activate the impurities. In the high-temperature heating step, the boron introduced into the silicon nitride film 5 causes penetration and diffusion.
A thermal process at a low temperature of 0 ° C. or less is desirable.

Thereafter, a normal self-aligned silicidation process, interlayer film deposition, and metallization process are performed to form a semiconductor device. That is, in the first embodiment, the silicon nitride film 5 is deposited on the silicon film 3a to which the P-type impurity is added, boron is introduced into the silicon nitride film 5, and the silicon substrate 1 is heat-treated at a low temperature.

At this time, boron introduced into the silicon nitride film 5 easily forms a compound with hydrogen, such as B ₂ H ₆ . Therefore, hydrogen contained at the time of forming the silicon nitride film 5 is removed by a low-temperature heat treatment at a low temperature and at a low temperature.
Can be removed without a change in film quality.

FIGS. 2A to 2D show a second embodiment of the method for manufacturing a semiconductor device according to the present invention.
The method of manufacturing a semiconductor device according to the second embodiment includes a step of forming a gate insulating film on a surface of a semiconductor substrate; a step of forming a silicon film for a gate cap insulating film on the gate insulating film; Depositing a silicon nitride film for a gate cap film on the film, and adding boron to at least a silicon nitride film of the silicon nitride film deposited on a P-type gate formation planned region of the silicon film And heat treating the semiconductor substrate at a temperature at which boron and hydrogen in the silicon nitride film are combined.

(Embodiment 2) First, as shown in FIG. 2A, an element isolation insulating film 4 is formed on a P-type semiconductor substrate 1 by a LOCOS method, and is formed on a P-type semiconductor substrate 1 by a thermal oxidation method. A gate insulating film 2 having a thickness of 6 nm is formed.

Thereafter, a silicon film 3 is deposited to a thickness of 200 nm, and further, using lithography and ion implantation techniques, P + (phosphorus) is applied to the silicon film to be the NMOS region and B + to the silicon film to be the PMOS region. (Boron) is introduced.

Thereafter, a metal silicide (for example, tungsten silicide) 21 is deposited on the entire surface of the substrate, and a silicon nitride film 5 for gate cap is deposited to a thickness of 100 nm by using a low pressure CVD method as in the first embodiment. .

Thereafter, boron B is ion-implanted.
+ At an acceleration voltage of ¹⁵ keV and a dose of 1 × 10 ¹⁵ (atoms /
cm ³ ) and doping in a nitrogen atmosphere at 650 ° C.
Heat treatment for a minute. In order to combine hydrogen desorbed in the silicon nitride film 5 with boron and desorb it, it is efficient to perform heat treatment at 600 ° C. or higher.

Next, as shown in FIG. 2B, the silicon nitride film 5, tungsten silicide 4, and silicon film 3 are anisotropically etched by a lithography process and RIE (reactive ion etching). The gate cap 5a and the gate electrodes 4a and 3a are processed.

Further, As + and BF ₂ + are introduced into the NMOS diffusion layer region and the PMOS diffusion layer region by using lithography and ion implantation techniques, thereby obtaining shallow source / drain diffusion layers 6.

Next, as shown in FIG.
The silicon nitride film 8 for the gate side wall is
nm. Next, as shown in FIG. 2D, the silicon nitride film 8 is processed using an anisotropic etching technique to form a gate sidewall 8a. Then, after doping the source / drain region 7 with an impurity, annealing is performed for 60 minutes in a nitrogen atmosphere at 850 ° C. to activate the impurity. In the high-temperature heating step, boron introduced into the silicon nitride film 5 causes penetration and diffusion.
In order to prevent this, a heating step at a low temperature of 800 ° C. or less is desirable.

Thereafter, a semiconductor element is formed by performing a normal self-aligned silicidation process, interlayer film deposition, and metallization process. That is, also in the second embodiment, the hydrogen contained during the formation of the silicon nitride film 5 can be removed at a low heat treatment temperature and low temperature without changing the film quality of the silicon nitride film 5.

In each of the above embodiments, the following modifications can be made. The silicon film may be an amorphous silicon film, a polycrystalline silicon film, a stacked film, a single-layer film, and even if impurities are doped, non-doped silicon. It may be a membrane.

Further, the silicon film may be obtained by performing doping by ion implantation, solid phase diffusion, vapor phase diffusion, or in-situ doping technique on each of the NMOS region and the PMOS region through a lithography process.

Also, in each of the above embodiments, the lightly dope LDD (Lightly Dope) is used as the drain structure of the MOS transistor.
d drain) structure, but GDD (gradual diffused)
drain) structure or a single drain structure.

In each of the above embodiments, the self-aligned silicide process is used, but the silicide bonding need not be performed. Further, in each of the above embodiments, boron is used as the P-type impurity, but a boron compound such as boron fluoride or boron chloride may be used.

In each of the above embodiments, tungsten silicide was used as the refractory metal formed on the gate silicon film. However, Co, Ni, Mo, Zr, Hf, Ta, Pd, or Pt silicide may be used. These metals themselves may be used.

In each of the above embodiments, the LOCOS method is used to realize the element isolation structure. However, an embedded element isolation technique may be used. In each of the above embodiments, the boron doped in the silicon film is doped before the silicon nitride film is deposited, but may be doped after the silicon nitride film is deposited.

In each of the above embodiments, boron is used as an element for assisting hydrogen elimination, but nitrogen may be used instead of boron. Even if boron is introduced into the silicon nitride film as described above, since the diffusion coefficient of boron in the silicon nitride film is extremely small, the introduced boron diffuses into the underlying silicon film, and the performance in the N-type silicon gate is reduced. Does not deteriorate.

According to the present invention, it is possible to effectively remove hydrogen, which is a factor of increasing the penetration and diffusion phenomenon of boron, to suppress the penetration and diffusion of boron, to have no threshold fluctuation, and to have good cutoff characteristics. Thus, it is possible to form a MOSFET having a highly reliable gate insulating film. The adverse effect caused by the diffusion of impurities in the surface channel type pMOS is eliminated, and the surface channel type CMOS can be easily formed. Surface channel CMOS facilitates miniaturization, high performance, and high integration of MOS transistors.

[0049]

As described above, according to the present invention, when manufacturing a surface channel type CMOS transistor, the penetration diffusion phenomenon of boron caused by the silicon nitride film is suppressed, and a P-type silicon gate having good MOS characteristics is provided. A method of manufacturing a semiconductor device capable of realizing a PMOSFET having the same can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a substrate in a main step according to a first embodiment of a method of manufacturing a semiconductor device of the present invention.

FIG. 2 is a cross-sectional view showing a substrate in a main step according to a second embodiment of the method of manufacturing a semiconductor device of the present invention.

FIG. 3 is a cross-sectional view showing a substrate in a main step of a conventional method of manufacturing a surface channel CMOSFET.

FIG. 4 is a view showing a boron diffusion acceleration characteristic by H ₂ .

FIG. 5 is a view showing a boron diffusion acceleration characteristic by a silicon nitride film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 2 ... Gate insulating film, 3 ... Silicon film, 4 ... Element isolation region, 5 ... Silicon nitride film, 6 ... Source / drain diffusion layer 7: source / drain region, 8: silicon nitride film, 21: tungsten silicide.

Claims (12)

[Claims] A step of forming a gate insulating film on a surface of a semiconductor substrate; a step of forming a silicon film on the gate insulating film; a step of depositing a silicon nitride film on the silicon film; Of adding boron or a boron compound to at least a silicon nitride film deposited on a region where a P-type gate is to be formed in the silicon film; and removing the semiconductor substrate from boron or a boron compound in the silicon nitride film and hydrogen. Performing a heat treatment at a temperature at which the semiconductor device is combined with the semiconductor device. 2. The method according to claim 1, further comprising, between the step of forming a silicon film on the gate insulating film and the step of depositing a silicon nitride film on the silicon film, a step of depositing a refractory metal film on the silicon film. 2. The method according to claim 1, further comprising:
The manufacturing method of the semiconductor device described in the above. 3. The step of performing the heat treatment is performed at a temperature equal to or higher than a temperature at which boron or a boron compound in the silicon nitride film is combined with hydrogen, and the diffusion of boron or the boron compound by the hydrogen in the silicon nitride film is accelerated. 3. The method for manufacturing a semiconductor device according to claim 1, wherein the heat treatment is performed at a temperature lower than the temperature at which the heat treatment does not occur. 4. The method according to claim 1, wherein the heat treatment is performed at a temperature of 800 ° C. or less. 5. The method for manufacturing a semiconductor device according to claim 1, wherein the heat treatment is performed at a temperature of 600 ° C. or higher. 6. The method according to claim 6, further comprising the step of adding boron or a boron compound to the silicon film between the step of forming a silicon film on the gate insulating film and the step of depositing a silicon nitride film on the silicon film. The method of manufacturing a semiconductor device according to claim 1, further comprising: 7. The method according to claim 1, wherein boron or a boron compound is added to the silicon film simultaneously with the step of adding boron or a boron compound to the silicon nitride film. Of manufacturing a semiconductor device. 8. The method according to claim 1, wherein the step of depositing a silicon nitride film on the silicon film includes depositing a silicon nitride film on the entire surface of the semiconductor substrate. A method for manufacturing a semiconductor device. 9. A step of forming a gate insulating film on a surface of a semiconductor substrate; a step of forming a silicon film on the gate insulating film; and a step of selectively removing the silicon film to form a gate electrode. Depositing a silicon nitride film for forming a gate sidewall on the silicon film; adding boron or a boron compound to the silicon nitride film; and forming the semiconductor substrate with boron or a boron compound in the silicon nitride film. Performing a heat treatment at a temperature at which hydrogen bonds with the semiconductor device. 10. A step of forming a gate insulating film on a surface of a silicon substrate, a step of forming a silicon film on the gate insulating film, and a step of selectively removing the silicon film to form a gate electrode. Depositing a silicon nitride film for forming a gate sidewall on the silicon film, processing the silicon film by anisotropic etching to form a gate sidewall, and forming a gate sidewall in the silicon nitride film and the silicon substrate. Manufacturing a semiconductor device, comprising: simultaneously adding boron or a boron compound; and performing a heat treatment on the silicon substrate at a temperature at which boron or the boron compound in the silicon nitride film is combined with hydrogen. Method. 11. The step of performing the heat treatment is performed at a temperature equal to or higher than a temperature at which boron or a boron compound in the silicon nitride film is bonded to hydrogen, and the speed of diffusion of the boron or boron compound by the hydrogen in the silicon nitride film is increased. 10. The heat treatment is performed at a temperature lower than a temperature at which no heat is generated.
0. A method for manufacturing a semiconductor device according to item 0. 12. A step of forming a gate insulating film on a surface of a semiconductor substrate; a step of forming a silicon film on the gate insulating film; a step of depositing a silicon nitride film on the silicon film; Wherein nitrogen is added to at least a silicon nitride film deposited on a region where a P-type gate is to be formed in the silicon film; and the semiconductor substrate is heated at a temperature at which nitrogen and hydrogen in the silicon nitride film are combined. Performing a heat treatment.