JP3063840B2 - Semiconductor device and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, to improvement of hot carrier resistance.

[0002]

2. Description of the Related Art Generally, in a method of manufacturing a semiconductor device, a BPSG film is often annealed at 800 ° C. or higher.

However, recently, as a film formed under the BPSG film, for example, as a material of a component of a transistor,
Those without heat resistance are being adopted. Titanium salicide and the like are examples of a material having low heat resistance. When excessive heat is applied to a material having low heat resistance in a semiconductor device, the electrical resistance of a film made of this material increases significantly, and the essential performance required of the semiconductor device is not exhibited.

On the other hand, when the BPSG film is annealed at a low temperature to protect the film made of titanium salicide,
Due to the doping in the PSG film, the water contained in this film does not evaporate during annealing but remains in the completed semiconductor device. Then, while using the completed semiconductor device, the remaining water diffuses to the transistor. As a result, the hot carrier resistance of the semiconductor device deteriorates.

On the other hand, there is a technique of forming a silicon oxide film by a parallel plate plasma CVD method without using a BPSG film. In this technology, BPS containing water
Since the G film is not used, low-temperature annealing can be performed. However, since the silicon oxide film is formed with the SiH ₄ gas and the N ₂ O gas, hydrogen remains in the silicon oxide film of the completed semiconductor device. Then, during use of the completed semiconductor device, the remaining hydrogen diffuses to the transistor. As a result, the hot carrier resistance of the semiconductor device deteriorates.

Further, a semiconductor device having a structure capable of blocking impurities such as water and phosphorus which is going to diffuse into a transistor in order to realize excellent hot carrier resistance is disclosed in Japanese Patent Publication No.
No. 16186 discloses this. In the manufacturing process of this semiconductor device, the decompression CV
A silicon nitride film is formed by Method D. Although this semiconductor device has a BPSG film, water may remain in the BPSG film.
It is not necessary to perform the above annealing.

Referring to FIG. 4, a semiconductor device similar to this publication is manufactured as follows.

A gate oxide film 4 is formed on a semiconductor substrate 401.
02, a DOPOS gate electrode 403 is formed.
A diffusion layer 404 is formed on both sides of the DOPOS gate electrode 403 of the semiconductor substrate 401. Further, a titanium salicide layer 405 is formed on the diffusion layer 404 and the DOPOS gate electrode 403, respectively. Also, the gate oxide film 4
02 and a side wall oxide film 406 is formed on the side surface of the DOPOS gate electrode 403.

On this structure, a normal-pressure silicon oxide film 40 is formed by a normal-pressure CVD method (film formation temperature: about 400 ° C.).
7 is formed to about 1000 angstroms. Further, a low-pressure silicon nitride film 408 made of dichlorosilane and NH _{3 is} formed on the normal-pressure silicon oxide film 407 by low-pressure CVD (film formation temperature: about 700 ° C.) to a thickness of 1000 Å. Next, an ozone-TEOS-BPSG film 409 is formed on the reduced-pressure silicon nitride film 408 by a normal pressure CVD method (at a deposition temperature of about 500 ° C.) at about 7000 Å. Thereafter, reflow is performed for flattening. As described above, the semiconductor device shown in FIG. 4 was manufactured.

[0010]

According to the technique disclosed in the above publication, since water may remain in the BPSG film, the annealing temperature for the BPSG film may be 800 ° C. or less. However, when forming the silicon nitride film, 650 ° C.
It is necessary to perform the above heat treatment. This is because the decompression C
The combination of dichlorosilane and NH ₃ gas used for forming a silicon nitride film by the VD method hardly causes a thermal reaction below 650 ° C., that is, 650 ° C.
In the following, a silicon nitride film cannot be formed. Incidentally, the deposition rate of this silicon nitride film is:
At 650 ° C., it is about 3 Å / min.

In the technique disclosed in the above-mentioned publication which requires a heat treatment at 650 ° C. or higher, the electric resistance of a film made of a material having low heat resistance such as titanium salicide eventually increases, and the obtained semiconductor device has Performance cannot be demonstrated.

An object of the present invention is to provide a semiconductor device having a low electrical resistance and excellent hot carrier resistance even in a structure having a film made of a material having low heat resistance, and a method of manufacturing the same. is there.

[0013]

According to the present invention, there is provided a semiconductor substrate having a transistor, a silicon nitride film formed on the semiconductor substrate by high-density plasma chemical vapor deposition, and a high-density silicon nitride film formed on the silicon nitride film. And a silicon oxide film formed by density plasma chemical vapor deposition.

According to the present invention, there is also provided the semiconductor device wherein the silicon nitride film contains a silicon compound not containing hydrogen and nitrogen.

According to the present invention, the silicon compound containing no hydrogen may further comprise SiF ₄ , SiI ₄ , and Si
The semiconductor device includes at least one selected from Cl ₄ .

According to the present invention, there is also provided the semiconductor device, wherein at least a part of a gate portion, a source portion, and a drain portion of the transistor contains a titanium atom.

According to the present invention, there is further provided a step of forming a silicon nitride film on a semiconductor substrate having a transistor by high-density plasma chemical vapor deposition, and a step of forming a silicon oxide film on the silicon nitride film by high-density plasma chemical vapor deposition. And a step of forming a film.

According to the present invention, the method for manufacturing a semiconductor device, wherein the silicon nitride film contains a silicon compound not containing hydrogen and nitrogen.

According to the present invention, the silicon compound containing no hydrogen may further comprise SiF ₄ , SiI ₄ , and Si
A method for manufacturing the semiconductor device including at least one selected from Cl ₄ is obtained.

According to the present invention, there is also provided a method of manufacturing the semiconductor device, wherein at least a part of a gate portion, a source portion, and a drain portion of the transistor contains a titanium atom.

[0021]

According to the present invention, a silicon nitride film is formed on a semiconductor substrate having a transistor having a film made of a material having low heat resistance such as titanium salicide by a high-density plasma CVD method, and a high-density plasma CVD method is further formed thereon. The silicon oxide film is formed by the method. High density plasma C
According to the VD method, a silicon nitride film or a silicon oxide film can be formed at a low temperature. That is, a film made of a material having low heat resistance in a semiconductor device being manufactured is not heated. For this reason,
The electric resistance of a film made of a material having low heat resistance does not increase.

Further, according to the present invention, since there is no dope such as boron or phosphorus, water is not contained in the silicon nitride film or the silicon oxide film, and, of course, does not remain. Therefore, there is no deterioration in hot carrier resistance due to diffusion of remaining water into the transistor.

Further, according to the present invention, when forming a silicon nitride film, a gas containing no hydrogen can be used, so that hydrogen is not contained in the silicon nitride film and, of course, does not remain. Therefore, there is no deterioration in hot carrier resistance due to diffusion of the remaining hydrogen into the transistor. The reason why a gas containing no hydrogen can be used when forming the silicon nitride film is that high-density plasma CVD is applied with enough plasma energy to decompose a silicon compound containing no hydrogen.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a semiconductor device according to an embodiment of the present invention will be described with reference to the drawings.

Referring to FIG. 1, a semiconductor device according to an embodiment of the present invention includes a semiconductor substrate 101 and a gate oxide film 1.
02 and DOPOS which is a phosphorus-doped polycrystalline silicon film
A gate electrode 103, a diffusion layer 104, a titanium salicide layer 105, a normal-pressure silicon oxide film 107 by normal-pressure CVD, a high-density silicon nitride film 108 by high-density plasma CVD, and a high-pressure silicon nitride film 108 by high-density plasma CVD. Density silicon oxide film 109. The upper surface of the high-density silicon oxide film 109 is flattened, and a metal wiring layer is formed on this surface in a later step.

More specifically, on the semiconductor substrate 101,
A gate oxide film 102 is formed. Gate oxide film 1
02, a DOPOS gate electrode 103 is formed. Diffusion layers 104 are formed on both sides of the (DOPOS) gate electrode 103 on the semiconductor substrate 101. On the diffusion layer 104 and the DOPOS gate electrode 103, a titanium salicide layer 105 is formed.
An oxide film sidewall film 106 is formed on side surfaces of the gate oxide film 102, the DOPOS gate electrode 103, and the titanium salicide layer 105. Further, a normal pressure silicon oxide film 107 is formed so as to cover them. On the normal-pressure silicon oxide film 107, a high-density silicon nitride film 108 is formed. On the high-density silicon nitride film 108, a high-density silicon oxide film 109 is formed by a high-density plasma CVD method.

[0027]

[Embodiment 1] A method of manufacturing a semiconductor device according to Embodiment 1 of the present invention will be described below with reference to the drawings.

Referring to FIG. 2A, similar to the conventional example,
D on a semiconductor substrate 201 via a gate oxide film 202
An OPOS gate electrode 203 is formed. Semiconductor substrate 20
1 on both sides of the DOPOS gate electrode 203.
4 is formed. Further, the titanium salicide layer 2 is formed on the diffusion layer 204 and the DOPOS gate electrode 203, respectively.
05 is formed. Further, the gate oxide film 202 and the DO
A side wall oxide film 206 is formed on the side surface of the POS gate electrode 203.

On this structure, a normal-pressure silicon oxide film 207 is formed to a thickness of about 1000 angstroms by a normal-pressure CVD method. The film formation temperature is about 400 ° C., SiH ₄ ,
O ₂ gas was used. The normal-pressure silicon oxide film 207 was formed for the purpose of alleviating plasma damage.

Next, I as a high-density plasma CVD method
High density silicon nitride film 2 by PC plasma CVD
08 is formed at about 1000 angstroms. The film formation temperature was about 300 ° C., and SiF ₄ gas, N ₂ gas, and Ar were used.

Next, a high-density silicon oxide film 209 is formed on the high-density silicon nitride film 208 by IPC plasma CVD at about 10,000 angstroms.
SiH ₄ , O ₂ , and Ar were used. This step is
The formation of the high-density silicon nitride film 208 was performed continuously in the same deposition chamber as the high-density silicon nitride film 208. As described above, the structure shown in FIG. 2A was manufactured. In FIG. 2A, a high density silicon oxide film 20 is formed.
The surface of No. 9 has an acute angle in cross section by the IPC plasma CVD method.

Next, referring to FIG. 2B, the high-density silicon oxide film 209 is flattened. The surface of the high-density silicon oxide film 209 is flattened by chemical polishing or 4000 angstrom polishing by chemical and mechanical polishing. As described above, the semiconductor device shown in FIG. 2B was manufactured. On the flattened surface of the high-density silicon oxide film 209, a metal wiring layer is formed in a later step.

Embodiment 2 Hereinafter, a method for manufacturing a semiconductor device according to Embodiment 2 of the present invention will be described with reference to the drawings.
Referring to FIGS. 3A and 3B, the structural difference between the second embodiment and the first embodiment is that high-density plasma CVD is used.
Is that the high density silicon nitride film 307 is formed directly on the titanium salicide layer 305. The advantage is that the high-density silicon nitride film 307 can function as a stopper nitride film when forming a contact in a self-aligned manner.

Referring to FIG. 3A, a DOPOS gate electrode 303 is formed on a semiconductor substrate 301 with a gate oxide film 302 interposed therebetween, as in the conventional example. A diffusion layer 304 is formed on both sides of the DOPOS gate electrode 303 of the semiconductor substrate 301. Further, the diffusion layer 304 and the DOPO
A titanium salicide layer 305 is formed on each of the S gate electrodes 303. Further, a sidewall oxide film 306 is formed on side surfaces of the gate oxide film 302 and the DOPOS gate electrode 303.

On such a structure, an IPC plasma C
The high-density silicon nitride film 307 is formed by
0 angstrom is formed. The film formation temperature was about 300 ° C., and SiCl ₄ gas and N ₂ gas were used.

Next, a high-density silicon oxide film 308 is formed on the high-density silicon nitride film 307 by IPC plasma CVD at about 10,000 angstroms.
SiH ₄ , O ₂ , and Ar were used. This step is
The formation of the high-density silicon nitride film 307 was performed continuously in the same deposition chamber as the high-density silicon nitride film 307. As described above, the structure shown in FIG. 3A was manufactured. In FIG. 3A, a high density silicon oxide film 30 is formed.
The surface of No. 8 has an acute angle in cross section by the IPC plasma CVD method.

Next, referring to FIG. 3B, the high density silicon oxide film 308 is flattened. The surface of the high-density silicon oxide film 308 is planarized by chemical polishing or 4000 angstrom polishing by chemical and mechanical polishing. As described above, the semiconductor device shown in FIG. 3B was manufactured. A metal wiring layer is formed on the flattened surface of the high-density silicon oxide film 308 in a later step.

The method of manufacturing a semiconductor device according to the present invention is not limited to the above two embodiments. For example, SiI ₄ or the like may be used as a silicon compound containing no hydrogen used for forming a high-density silicon nitride film. As the high-density plasma source, an ECR plasma source, a helicon wave plasma source, or the like may be used in addition to the IPC plasma source.

[0039]

As is apparent from the above description, according to the present invention, even if the structure has a film made of a material having low heat resistance such as titanium salicide, the electric resistance of the film is low and the hot carrier A semiconductor device having excellent resistance can be obtained.

According to the present invention, a silicon nitride film or a silicon oxide film can be formed at a low temperature by a high-density plasma CVD method. That is, a film made of a material having low heat resistance in a semiconductor device being manufactured is not heated. Therefore, the electric resistance of the film made of a material having low heat resistance does not increase.

Further, according to the present invention, since there is no doping such as boron or phosphorus, water is not contained in the silicon nitride film or silicon oxide film and, of course, does not remain. Therefore, there is no deterioration in hot carrier resistance due to diffusion of remaining water into the transistor.

Further, according to the present invention, when forming the silicon nitride film, a gas containing no hydrogen can be used, so that hydrogen is not contained in the silicon nitride film and, of course, does not remain. Therefore, there is no deterioration in hot carrier resistance due to diffusion of the remaining hydrogen into the transistor. The reason why a gas containing no hydrogen can be used when forming the silicon nitride film is that high-density plasma CVD is applied with enough plasma energy to decompose a silicon compound containing no hydrogen.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a semiconductor device and a method of manufacturing the same according to an embodiment of the present invention.

FIGS. 2A and 2B are views for explaining a semiconductor device and a method for manufacturing the same according to a first embodiment of the present invention; FIGS.

FIGS. 3A and 3B are diagrams illustrating a semiconductor device and a method of manufacturing the same according to a second embodiment of the present invention; FIGS.

FIG. 4 is a diagram illustrating a conventional semiconductor device and a method of manufacturing the same.

[Explanation of symbols]

101, 201, 301, 401 Semiconductor substrate 102, 202, 302, 402 Gate oxide film 103, 203, 303, 403 DOPOS gate electrode 104, 204, 304, 404 Diffusion layer 105, 205, 305, 405 Titanium salicide layer 106, 206, 306, 406 Side wall oxide film 107, 207, 407 Normal pressure silicon oxide film 108, 208, 307 High density silicon nitride film 109, 209, 308 High density silicon oxide film 408 Low pressure silicon nitride film 409 Ozone-TEOS-BPSG film

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/316 H01L 21/318 H01L 29/78

Claims (8)

(57) [Claims] 1. A semiconductor substrate having a transistor, a silicon nitride film formed on the semiconductor substrate by high-density plasma chemical vapor deposition, and formed on the silicon nitride film by high-density plasma chemical vapor deposition. A semiconductor device having a silicon oxide film. 2. The semiconductor device according to claim 1, wherein said silicon nitride film contains a silicon compound not containing hydrogen and nitrogen. 3. The silicon compound not containing hydrogen,
3. The semiconductor device according to claim 2, comprising at least one selected from SiF ₄ , SiI ₄ , and SiCl ₄ . 4. The semiconductor device according to claim 1, wherein at least a part of a gate portion, a source portion, and a drain portion of the transistor includes a titanium atom. 5. A step of forming a silicon nitride film on a semiconductor substrate having a transistor by high-density plasma chemical vapor deposition, and a step of forming a silicon oxide film on the silicon nitride film by high-density plasma chemical vapor deposition. And a method for manufacturing a semiconductor device. 6. The method according to claim 5, wherein the silicon nitride film contains a silicon compound not containing hydrogen and nitrogen. 7. The silicon compound not containing hydrogen,
7. The method according to claim 6, comprising at least one selected from SiF ₄ , SiI ₄ , and SiCl ₄ . 8. The method of manufacturing a semiconductor device according to claim 5, wherein at least a part of a gate part, a source part, and a drain part of the transistor contains a titanium atom.