JP2000082811A - Semiconductor device wish titanium silicide film and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device having a titanium silicide film suppressing the achievement of fine wiring effect even if gate length or wiring width is reduced as well as manufacture thereof. SOLUTION: In order to manufacture a semiconductor device with a titanium silicide film, a metallic film 11 is formed by sputtering titanium on a gate electrode 14 and impurity layers 18 also tungsten on the metallic film 11 further sputtering tungsten on the metallic film 11 to form a protective film 15 and then the protective film 15, the titanium metallic film 11, the gate electrode 14 and the impurity layers 18 are heat-treated to be respectively reacted with the metallic film 11 for silicification so as to form titanium silicide films 13. Through these procedures, the achievelement of fine wiring effect can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a semiconductor device having a titanium silicide film and a method of manufacturing the same. In particular, the present invention relates to a semiconductor device having a titanium silicide film on a silicon-containing layer such as a gate electrode made of polycrystalline silicon and a silicon substrate surface impurity layer of a semiconductor device, and a method of manufacturing the same.

[0002]

2. Description of the Related Art As means for increasing the speed and integration of a semiconductor device, so-called salicide (Self-Aligned-Sil
icide) technology. This is, for example, FIG.
Gate electrode 2 in a MOS type semiconductor device as shown in FIG.
2, a metal silicide layer 26 is formed in a self-aligning manner on the impurity region 24 formed on the silicon substrate 20, that is, on the silicon-containing layer. It is desirable to keep the resistance of the metal silicide layer 26 low in order to speed up the circuit.

[0003]

However, it has been found that the technique using the above-mentioned titanium silicide film causes a problem called a fine line effect when the wiring is made thin.

[0004] That is, when the width of the gate electrode or the like is reduced to achieve high integration, there are two problems: a variation in the resistance of the titanium silicide layer; and an increase in the average value of the resistance. Problems arise.

The cause is considered as follows.
Titanium silicide has two crystal structures: a high resistance (about 100 Ω · cm) crystal structure (C49) and a low resistance (about 15 Ω · cm) crystal structure (C54). The high-resistance crystal structure (C49) is formed at a low temperature of about 400 ° C., whereas the low-resistance crystal structure (C54) is formed at a high temperature of about 700 ° C. For this reason, as the wiring becomes thinner, the layer transition from a high-resistance crystal structure to a low-resistance crystal structure is hindered, and the ratio of high-resistance crystals increases. Further, as the wiring becomes thinner, the variation in the ratio between the low-resistance crystal and the high-resistance crystal increases. From such a thing, it is considered that the above problem occurs.

Further, as a cause of the inhibition of the layer transition from the high-resistance crystal structure to the low-resistance crystal structure in the titanium silicide layer, it is considered that oxygen is mixed into the titanium silicide film and the influence of the stress of the titanium silicide film. Can be

As a method for preventing oxygen from being mixed into the titanium silicide film described above, the following manufacturing method has been considered.

(1) A metal film is formed by sputtering titanium.

(2) Then, a titanium nitride film is formed on the metal film by sputtering titanium in a nitrogen atmosphere as a protective film for preventing oxygen from entering.

(3) This is subjected to a heat treatment to silicide the metal film made of titanium.

(4) Finally, the unnecessary titanium film and the protective film made of titanium nitride which are not silicided are removed by etching.

However, in a semiconductor device manufactured by such a method using titanium nitride as a protective film, the influence of stress in the titanium silicide film cannot be completely avoided. Therefore, when the wiring width of the gate electrode or the like is about 0.3 μm or less, it is possible to sufficiently solve the two problems that the dispersion of the resistance in the titanium silicide layer becomes large and that the average value of the resistance becomes large. Can not.

The present invention has been made in consideration of the above circumstances, and has as its object to reduce the variation in resistance even when the wiring width of a gate electrode or the like becomes smaller than about 0.3 μm, and to reduce the resistance. It is an object of the present invention to provide a semiconductor device provided with a titanium silicide film having a small average value of and a method for manufacturing the same. Another object of the present invention is to provide a semiconductor device provided with a titanium silicide film in which a thin line effect is suppressed even when a gate length or a wiring width is reduced, and a method for manufacturing the same.

[0014]

In order to solve the above-mentioned problems, a method for manufacturing a semiconductor device according to a first aspect of the present invention comprises:
The method includes the following steps.

(A) An element isolation film on a silicon substrate
Forming a gate insulating film, a gate electrode, a side wall, and an impurity layer; and (b) further sputtering titanium on the silicon substrate, the gate electrode, the side wall, the impurity layer, and the element isolation film. Forming a metal film; (c) forming a protective film by sputtering tungsten on the titanium film following the sputtering of titanium; and (d) forming the protective film on the titanium film. Heating the impurity layer on the silicon substrate and the gate electrode to produce a silicide film containing titanium silicide as a main component on the impurity layer on the silicon substrate and the gate electrode; And removing the metal film and the protective film remaining on the device isolation film by etching.

As a result, a titanium silicide layer having no thin wire effect, a small variation in resistance, and a small average value of resistance can be used as a wiring layer, and a semiconductor device with high speed and high integration is manufactured. be able to.

A semiconductor device according to a second aspect of the present invention has the following structure.

(A) a gate insulating film, a side wall, an impurity layer, and an element isolation film disposed on a silicon substrate; (b) a gate electrode disposed on the gate insulating film; and (c) the impurity layer. And a titanium silicide produced as a main component when a metal film formed by sputtering titanium on the impurity layer and a protective film made of tungsten sputtered continuously thereon are subjected to heat treatment. A protection film comprising: a silicide film having the same composition as the silicide film; and (d) a metal film disposed on the gate electrode and formed by sputtering titanium on the gate electrode and tungsten continuously sputtered thereon. A silicide having the same composition as a silicide film containing titanium silicide as a main component produced when the film is subjected to a heat treatment. Film.

As a result, a titanium silicide layer having no thin wire effect, a small variation in resistance and a small average value of resistance can be used as a wiring layer, and a semiconductor device with high speed and high integration is manufactured. be able to.

A method of manufacturing a semiconductor device having a titanium silicide film according to a third aspect of the present invention includes the following steps.

(A) a step of forming a metal film by sputtering titanium on the silicon-containing layer; and (b), following the sputtering of titanium, sputtering tungsten on the titanium film to form a protective film. Forming; (c) heat-treating the metal film and the protective film to produce a silicide film containing titanium silicide as a main component on the silicon-containing layer; and (d) the metal film and the protective film. Removing the metal film and the protective film remaining without being silicided by etching.

Thus, not only the above semiconductor but also a semiconductor device having a titanium silicide layer can be manufactured.

A semiconductor device according to a fourth aspect of the present invention is a semiconductor device comprising: a silicon-containing layer; a metal film formed by sputtering titanium on the silicon-containing layer; Has the same composition as the silicide film containing titanium silicide as a main component produced on the silicon-containing layer when the protective film is formed by sputtering to form the protective film, and the heat treatment of the protective film, the metal film and the silicon-containing layer. And a silicide film.

Thus, not only the semiconductor described above, but also a semiconductor device having a titanium silicide layer can be provided.

In a method of manufacturing a semiconductor device having a titanium silicide film according to a fifth aspect of the present invention, a step of forming a titanium metal film on a silicon-containing layer and forming a tungsten protective film on the titanium metal film Heat treating the tungsten protective film, the titanium metal film, and the silicon-containing layer to cause the silicon-containing layer and the titanium metal film to react with each other to form a silicide. I do. Further, the silicon-containing layer may be a gate electrode made of polycrystalline silicon formed on a silicon substrate or an impurity layer formed on a silicon substrate.

In the method of manufacturing a semiconductor device having a titanium silicide film according to the fifth aspect, the use of tungsten as the protective film can suppress the occurrence of stress in the silicide film during silicidation. This makes it possible to obtain titanium silicide in which a layer transition from a high-resistance crystal structure (C49) to a low-resistance crystal structure (C54) easily occurs. For this reason, even if the gate length or the wiring is reduced, it is possible to suppress the occurrence of the fine line effect.

Preferably, the thickness of the protective film is smaller than the thickness of the metal film. Thereby, the occurrence of the thin line effect can be reliably suppressed.

It is preferable that the surface of the silicon-containing layer is not pre-amorphized before the step of forming the titanium metal film. This is because the effect of pre-amorphization that has been conventionally considered does not exist.

A semiconductor device provided with a titanium silicide film according to a sixth aspect of the present invention comprises a silicon-containing layer and a silicide film formed on the silicon-containing layer and containing titanium silicide as a main component, Tungsten is mixed in the surface of the silicide film. Also,
The silicide film is formed by forming a titanium metal film on the silicon-containing layer, forming a tungsten protective film on the titanium metal film, and heat-treating the tungsten protective film, the titanium metal film and the silicon-containing layer. It is preferable that the substrate is formed by forming Preferably, the silicon-containing layer is a gate electrode made of polycrystalline silicon formed on the silicon substrate or an impurity layer formed on the silicon substrate.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 to 6 are sectional views showing a method of manufacturing a semiconductor device according to an embodiment of the present invention.

First, as shown in FIG.
On the silicon substrate 10 between the element isolation films 19, a gate oxide film 12 as a gate insulating film is formed. LOCO is used as the element isolation film.
Structures such as S, semi-recess LOCOS, and shallow trench can be used. A gate electrode 14 made of polycrystalline silicon is formed on the gate oxide film 12, and a low concentration impurity layer 17 is formed by ion implantation using the gate electrode 14 as a mask. After that, a sidewall material 16 is formed on the sidewall of the gate electrode 14. Thereafter, an impurity layer (source / drain) 18 is formed on the silicon substrate 10 in a self-aligned manner using the gate electrode 14 and the side wall material 16 as a mask. Known methods are used for these forming methods.

Next, as shown in FIG.
4. A titanium film is formed on the entire surface of the substrate including the sidewall material 16, the impurity layer 18, and the element isolation film 19 to form the metal film 11. At this time, the thickness of the metal film 11 is, for example, 30 nm.
It is about. The thickness of the metal film 11 can be calculated by dividing the desired thickness of the titanium silicide film by a certain constant. In the present embodiment, this constant is about 2.5.

Thereafter, as shown in FIG. 3, tungsten is sputtered on the metal film 11 to form a protective film (Ca).
p) Form 15. At this time, the thickness of the protective film 15 is preferably smaller than that of the metal film 11, for example, 20 nm.
It is.

Next, as shown in FIG. 4, the metal film 11, the protective film 15, the impurity layer 18, and the gate electrode 14 are
Heat treatment at 00 ° C. for 30 seconds. By this heat treatment, the silicon in the impurity layer 18 and the gate electrode 14 and the metal film 11 are formed.
By reacting the titanium inside, a titanium silicide film 13 having a thickness of about 75 nm is formed on each surface of the gate electrode 14 and the impurity layer 18.

Thereafter, as shown in FIG.
The metal film 11 and the protection film 15 remaining without being silicided on the sidewalls 9 and the sidewalls 16 are removed by etching. At this time, for example, an etching solution obtained by adding aqueous hydrogen peroxide to aqueous ammonia is used. Next, the titanium silicide film 13
Then, an annealing process of heating at 800 ° C. for about 30 seconds is performed. This is for the purpose of activating the semiconductor element and changing the layer of the titanium silicide film 13 from a high-resistance crystal structure (C49) to a low-resistance crystal structure (C54).

Next, as shown in FIG. 6, a wiring as a semiconductor element, an interlayer insulating film, a protective film called passivation, and the like are formed. For this, a known technique can be used. That is, the interlayer insulating film 8 made of SiO ₂ is formed on the titanium silicide film 13, the element isolation film 19, and the side wall 16. Next, a contact hole located on the titanium silicide film 13 is formed in the interlayer insulating film 8, and an Al alloy wiring 9 for electrically connecting to the titanium silicide film 13 is formed in the contact hole. Al
As alloy wiring, Ti / TiN / Al-C
A wiring in which u / TiN are stacked may be used.

According to the above-described embodiment, when silicidation is performed, by using tungsten instead of titanium nitride as the protective film (Cap) 15, it is possible not only to prevent oxygen from being mixed into the silicide film, but also to use titanium silicide. Generation of stress in the film 13 can be suppressed. That is, it is considered that when the metal film 11 made of titanium is formed on the base (the gate electrode 14 or the impurity layer 18), a tensile stress is generated with respect to the base, and when the protective film 15 made of tungsten is formed on the metal film 11, the base is formed. It is considered that compressive stress is generated with respect to. As a result, the tensile stress is canceled by the compressive stress, and as a result, the occurrence of stress in the titanium silicide film 13 can be suppressed.
Thereby, a layer transition from a high-resistance crystal structure (C49) to a low-resistance crystal structure (C54) is likely to occur. For this reason, even if the gate length or the wiring is reduced, it is possible to suppress the occurrence of the fine line effect. As a result, high speed and high integration of the semiconductor device can be achieved.

The reason why it is preferable to form the thickness of the protective film 15 thinner than that of the metal film 11 is that, otherwise, the compressive stress of the protective film 15 is too strong as compared with the tensile stress of the metal film 11. This is because the effect of relaxing the stress in the titanium silicide film 13 cannot be sufficiently obtained.

FIG. 7 shows that the elements present on the surface of the titanium silicide film manufactured by the above-described manufacturing method are obtained by SIMS.
(Secondary ion mass spectrometry
9 is a graph showing the results of detection using the measurement method of FIG. This titanium silicide film is formed using a metal film made of titanium with a thickness of 25 nm and a protective film made of tungsten with a thickness of 10 nm. The surface of the titanium silicide film 13 after the etching step shown in FIG.
It is a result measured in. FIG. 7 shows that a small amount of tungsten W is located between the surface of the titanium silicide film and the depth of 100 nm.
It can be seen that exists. In addition, W exists at a higher concentration on the silicide film surface side, and W does not exist as the depth from the surface becomes deeper. This is because tungsten was used as the protective film 15, and this tungsten diffused in the metal film 11 and remained on the surface of the titanium silicide film 13.

FIG. 8 shows that the elements present on the surface of the titanium silicide film when the titanium silicide film is formed using titanium nitride instead of tungsten as the protective film are represented by SI.
It is a graph which shows the result detected using MS. That is, this titanium silicide film is formed using a metal film made of titanium having a thickness of 30 nm and a protective film made of titanium nitride having a thickness of 50 nm. From this figure, it can be seen that tungsten W
Does not exist. This is because tungsten is not used as the protective film.

From FIGS. 7 and 8, since a small amount of tungsten remains in the titanium silicide film of the semiconductor device manufactured by the manufacturing method according to the present embodiment, it is possible to specify the semiconductor device from the tungsten. Become.
That is, it can be said that the titanium silicide film having a slight amount of tungsten on the surface is manufactured by the above manufacturing method.

FIG. 9 is a graph showing the relationship between the wiring width (or gate length) L of the titanium silicide film manufactured by the above manufacturing method and the sheet resistance R of the titanium silicide film. That is, it shows the results of measuring the sheet resistance of these wirings by forming wirings of various widths using five types of titanium silicide films, and is a graph showing the wiring width dependence of the sheet resistance.

Here, the five types of titanium silicide films are:
A titanium silicide film formed by a titanium metal film having a thickness of 25 nm and a tungsten protective film having a thickness of 5 nm;
A titanium silicide film formed by a 5 nm titanium metal film and a 10 nm thick tungsten protective film, 25 n thick
m, a titanium silicide film formed by a titanium protective film having a thickness of 20 nm, a titanium silicide film formed by a titanium metal film having a thickness of 25 nm and a tungsten protective film having a thickness of 50 nm, and titanium metal having a thickness of 25 nm This is a titanium silicide film formed by a film and a titanium nitride protective film having a thickness of 50 nm.

FIG. 9 shows that the sheet resistance of the titanium silicide film using titanium nitride as the protective film sharply increases when the wiring width L becomes 0.25 μm or less. The sheet resistance of the titanium silicide film using tungsten having a thickness of 50 nm as the protective film rapidly increased when the wiring width L became 0.35 μm or less. On the other hand, a titanium silicide film using tungsten having a thickness of 20 nm, 10 nm, and 5 nm as a protective film has a wiring width L of 0.15 μm.
m, the sheet resistance could be reduced.

From these results, it was confirmed that the effect of the present embodiment as described above, that is, the effect of suppressing the occurrence of the thin line effect even when the gate length or the wiring was made thinner, was confirmed. Further, the thickness of the tungsten protective film is set to 50 nm.
It was also confirmed that the film thickness required the tungsten protective film to be formed thinner than the titanium metal film.

FIG. 10 shows that when W is used as a protective film,
4 is a graph showing the results of confirming that even if the surfaces of a gate electrode and an impurity layer are pre-amorphized, an effect that has been conventionally considered to be effective for reducing sheet resistance cannot be obtained. That is, before the metal film 11 is formed in the step shown in FIG. 2, the surface of each of the gate electrode 14 and the impurity layer 18 is ion-implanted with Ar ions, thereby preliminarily making the surface amorphous. It has been conventionally thought that the silicide film 13 can be formed to have a low resistance.

However, the sheet resistance of a wiring made of a titanium silicide film formed by using a tungsten protective film having a thickness of 10 nm with PRA-ION (pre-amorphization) is improved by protecting a 10 nm thick tungsten film without the PRA-ION. When compared with the sheet resistance of the wiring made of the titanium silicide film formed using the film, it was found that the resistance value was almost the same as shown in FIG. From this result, it was confirmed that a step of implanting Ar ions into the surfaces of the gate electrode 14 and the impurity layer 18 to make the surfaces amorphous was unnecessary.

The above embodiment does not limit the present invention, and other embodiments can be adopted without departing from the principle of the present invention.

[0050]

As described above, according to the present invention, a titanium silicide film having a small resistance variation and a small average resistance even when the wiring width of a gate electrode or the like becomes thinner than about 0.3 μm. And a method of manufacturing the same.

According to the present invention, the impurity-containing layer is silicided using the tungsten protective film. Therefore, it is possible to provide a semiconductor device provided with a titanium silicide film in which the generation of the fine line effect is suppressed even when the gate length or the wiring width is reduced, and a method for manufacturing the same.

[Brief description of the drawings]

FIG. 1 is a sectional view illustrating a method for manufacturing a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the method of manufacturing the semiconductor device according to the embodiment of the present invention, showing a step subsequent to FIG. 1;

FIG. 3 is a cross-sectional view showing the method of manufacturing the semiconductor device according to the embodiment of the present invention, showing a step subsequent to FIG. 2;

FIG. 4 is a cross-sectional view showing the method of manufacturing the semiconductor device according to the embodiment of the present invention, which shows the step subsequent to FIG. 3;

FIG. 5 is a cross-sectional view illustrating the method of manufacturing the semiconductor device according to the embodiment of the present invention, which shows the step subsequent to FIG. 4;

FIG. 6 is a cross-sectional view illustrating the method for manufacturing the semiconductor device according to the embodiment of the present invention, which illustrates the next step of FIG. 5;

FIG. 7 shows that elements present on the surface of the titanium silicide film manufactured by the manufacturing method according to the embodiment of the present invention are represented by SI.
It is a graph which shows the result detected using MS.

FIG. 8 is a graph showing a result of detecting an element present on the surface of a titanium silicide film using SIMS when the titanium silicide film is formed using titanium nitride as a protective film.

FIG. 9 is a graph showing a relationship between a wiring width L of a titanium silicide film manufactured by a manufacturing method according to an embodiment of the present invention and a sheet resistance R of the titanium silicide film.

FIG. 10 is a graph showing the results of confirming that the effect of reducing the resistance of the silicide film cannot be obtained even when the surfaces of the gate electrode and the impurity layer are made pre-amorphous.

FIG. 11 is a sectional view showing a semiconductor device having a titanium silicide film.

[Explanation of symbols]

Reference Signs List 8 interlayer insulating film 9 Al electrode 10 silicon substrate 11 metal film 12 gate oxide film 13 titanium silicide film 14 gate electrode 15 protective film 16 sidewall material 17 low concentration impurity layer 18 impurity layer 19 element isolation film 20 silicon substrate 22 gate electrode 24 impurity Region 26 Metal silicide layer

Claims (11)

[Claims] 1. A method for manufacturing a semiconductor device, comprising the following steps. (A) forming an element isolation film, a gate insulating film, a gate electrode, a sidewall, and an impurity layer on a silicon substrate; and (b) forming the silicon substrate, the gate electrode, the sidewall,
Forming a metal film by further sputtering titanium on the impurity layer and the element isolation film; and (c) sputtering tungsten on the titanium film to form a protective film, following the sputtering of titanium. (D) heat-treating the metal film, the protective film, the impurity layer on the silicon substrate, and the gate electrode to form titanium silicide on the impurity layer on the silicon substrate and the gate electrode. (E) removing a metal film and a protective film remaining on the side wall and the element isolation film by etching; 2. A semiconductor device having the following structure. (A) a gate insulating film, a side wall, an impurity layer, and an element isolation film disposed on a silicon substrate; (b) a gate electrode disposed on the gate insulating film; And a silicide film containing titanium silicide as a main component produced when a metal film formed by sputtering titanium on the impurity layer and a protective film made of tungsten sputtered continuously thereon are heated. Heating a silicide film having the same composition; and (d) a metal film formed on the gate electrode by sputtering titanium on the gate electrode and a protective film made of tungsten sputtered continuously on the metal film. A silicide film having the same composition as a silicide film containing titanium silicide as a main component, which is manufactured when the treatment is performed. 3. A method for manufacturing a semiconductor device having a titanium silicide film, comprising the following steps. (A) a step of forming a metal film by sputtering titanium on a silicon-containing layer; and (b) a step of forming a protective film by sputtering tungsten on the titanium film following the sputtering of titanium. (C) heat-treating the metal film and the protective film to produce a silicide film containing titanium silicide as a main component on the silicon-containing layer; and (d) silicidation of the metal film and the protective film. A step of removing the metal film and the protective film remaining without being etched. 4. A silicon-containing layer and a metal film formed on the silicon-containing layer by sputtering titanium on the silicon-containing layer, followed by sputtering of tungsten to form a protective film, thereby forming a protective film. A film, a silicide film having the same composition as a silicide film containing titanium silicide as a main component produced on the silicon-containing layer when the metal film and the silicon-containing layer are heat-treated. Semiconductor device. 5. A step of forming a titanium metal film on the silicon-containing layer, a step of forming a tungsten protective film on the titanium metal film, and heat-treating the tungsten protective film, the titanium metal film, and the silicon-containing layer. Performing a reaction between the silicon-containing layer and the titanium metal film to form a silicide, thereby producing a semiconductor device having a titanium silicide film. 6. The titanium silicide film according to claim 5, wherein said silicon-containing layer is a gate electrode made of polycrystalline silicon formed on a silicon substrate or an impurity layer formed on a silicon substrate. Of manufacturing a semiconductor device having the same. 7. The method for manufacturing a semiconductor device having a titanium silicide film according to claim 5, wherein the thickness of the protective film is smaller than the thickness of the metal film. 8. The titanium silicide according to claim 5, wherein the surface of the silicon-containing layer is not pre-amorphized before the step of forming the titanium metal film. A method for manufacturing a semiconductor device having a film. 9. A semiconductor device comprising: a silicon-containing layer; and a silicide film containing titanium silicide as a main component formed on the silicon-containing layer, wherein tungsten is mixed into the surface of the silicide film. Semiconductor device provided with a titanium silicide film. 10. The silicide film includes a titanium metal film formed on the silicon-containing layer, a tungsten protective film formed on the titanium metal film, the tungsten protective film, the titanium metal film, and the silicon-containing layer. 10. The semiconductor device provided with a titanium silicide film according to claim 9, wherein the semiconductor device is formed by heat-treating to silicide. 11. The titanium silicide according to claim 9, wherein the silicon-containing layer is a gate electrode made of polycrystalline silicon formed on a silicon substrate or an impurity layer formed on a silicon substrate. A semiconductor device having a film.