JP2740722B2 - 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 in which a high melting point metal silicide film serving as an electrode, a wiring, etc. is provided above a semiconductor substrate and a method of manufacturing the same. The present invention relates to a measure for improving adhesion to a film.

[0002]

2. Description of the Related Art Generally, in a semiconductor device such as a large-scale LSI in which semiconductor elements are highly integrated, the electric resistance of a wiring for transmitting a signal from one circuit element to another circuit element determines the speed of the semiconductor device. Has become a major factor. Therefore,
A wiring material that is an electrode of a transistor and connects elements directly as a wiring is first required to have low electric resistance. As a wiring material having such a low electric resistance, there is a high melting point metal silicide. This high melting point metal silicide has a lower resistance than polycrystalline silicon, and has a wiring layer at a lower cost than a manufacturing method of forming a multilayer metal wiring. Since it has an advantage that it can be realized, it has recently been frequently used as a wiring material.

[0003] Materials belonging to the refractory metal silicide include molybdenum silicide (MoSix), titanium silicide (TiSix), and tungsten silicide (WS).
ix), etc., each of which has a lower resistance than polycrystalline silicon and can easily form a film. However, these materials are liable to be oxidized, and a high melting point metal component such as tungsten (W) diffuses into the oxide film and reacts, thereby deteriorating the characteristics of the semiconductor element and causing peeling of the film. In many cases, a polycrystalline silicon film is interposed between the gate insulating film and the insulating film without directly contacting the gate insulating film or the like.

FIG. 16 is a sectional view of a semiconductor device A as a first conventional example in which a refractory metal silicide film is applied to a MOS type semiconductor device. A gate insulating film 2 (thickness 5) made of silicon dioxide (SiO2) is formed on a silicon substrate body 1.
nm to 16 nm) by oxidizing silicon, further forming a polycrystalline silicon film 3 (thickness: 50 to 200 nm), and implanting a gate impurity such as arsenic by ion implantation at an implantation energy of 40 keV and an implantation dose of 4 to 8 nm. × 1
Introduced under the condition of 0 ¹⁵ cm ^-3 , and then tungsten silicide film 4 (WSix) (thickness 50 to 200 nm)
Are laminated. After the tungsten silicide film 4 is deposited, a silicon oxide film 5 (thickness: 50 to 2) made of silicon dioxide (SiO2) is formed by chemical vapor deposition (CVD).
00 nm). Further, patterning is performed to form a polycrystalline silicon film 3 and a tungsten silicide film 4.
And the silicon oxide film 5 are sequentially etched to form a gate electrode. Further, in the subsequent steps, a heat treatment is performed at a temperature of 850 ° C. to 950 ° C. for the purpose of activating the impurities, crystallizing the refractory metal silicide film 4 and flattening the interlayer film.

In FIG. 16, when the gate insulating film 2 and the tungsten silicide film 4 are in direct contact with each other, tungsten reacts with silicon dioxide, causing a leak current between the gate and the source or between the gate and the drain. Or the reliability of the gate insulating film is deteriorated. Therefore, a polycrystalline silicon film 3 into which an impurity is introduced is interposed between the tungsten silicide film 4 and the gate insulating film 2, and a gate electrode is formed by a laminated film of the polycrystalline silicon film 3 and the tungsten silicide film 4. I am trying to do it.

After the tungsten silicide film 4 is deposited, the silicon oxide film 5 is formed thereon because the tungsten silicide film 4 is rapidly oxidized in the subsequent heat treatment step, so that the tungsten silicide film 4 is rapidly oxidized between the wirings and between the source and the drain. This is to prevent short-circuiting of the gate electrode and introduction of impurities into the gate during another ion implantation step.

As disclosed in, for example, JP-A-63-76479, an amorphous silicon film or a polycrystalline silicon film is deposited on a tungsten silicide film 4 to prevent oxidation of the high melting point metal silicide film. Although there is an attempt to do so, a structure in which a polycrystalline silicon film remains on the silicide film has to be formed, so that a contact with a wiring must be formed in the polycrystalline silicon film. Therefore, there is a possibility that the advantage of the low resistance of the refractory metal silicide film cannot be sufficiently exhibited. Therefore,
As described above, the silicon oxide film is deposited on the refractory metal silicide film.

FIG. 17 shows a concentration profile of oxygen (O) and arsenic (As), which is an n-type impurity, from the silicon oxide film 5 to the silicon substrate main body 1. N-type impurities such as arsenic (As) tend to accumulate at the interface with the oxide film. In this case, the gate insulating film 2 (SiO2
) And the polycrystalline silicon film 3 (polySi), and the interface between the tungsten silicide film 4 (WSix) and the silicon oxide film 5 (SiO2) have high concentrations of arsenic (As).

FIG. 20 shows boron (B) and oxygen (O) in the same semiconductor device configuration as that of FIG. 16 in the case where boron ions as p-type impurities are introduced as gate impurities instead of n-type impurities. 3) shows the profile of the concentration. As shown in the figure, boron (B)
Is different from arsenic in the distribution state in the tungsten silicide film 4 and the polycrystalline silicon film 3 after the heat treatment.
That is, boron (B) is used as the tungsten silicide film 4.
(WSix) and the silicon oxide film 5 (SiO2) are accumulated at the interface between the silicon oxide film 5 and the polycrystalline silicon film 3 (polySi).
The concentration in the inside is low. Since the difference in thermal shrinkage between the tungsten silicide film 4 and the silicon oxide film 5 is large, stress is concentrated on the interface between the tungsten silicide film 4 and the silicon oxide film 5 by the heat treatment after the ion implantation. This is because the structure of the tungsten silicide film 4 near the interface is disturbed, and boron easily aggregates in the disturbed region. Also, since the solid solubility limit of boron in the polycrystalline silicon film 3 is smaller than that in the tungsten silicide film 4, boron in the polycrystalline silicon film 3 is sucked out to the tungsten silicide film 4 side and diffuses. Then, the concentration of boron (B) in the polycrystalline silicon film 3 decreases. That is, boron tends to have a larger effect of aggregating impurities on the interface than arsenic.

Although a tungsten silicide film is used here as a part of the gate electrode, the same applies to a manufacturing process using a molybdenum silicide film or a titanium silicide film.

FIG. 18 shows a second conventional example. After a tungsten silicide film 4 is deposited, a silicon nitride film 6 of silicon nitride (Si3 N4) (with a thickness of 50 to 50 mm) is formed.
1 shows a cross-sectional view of a semiconductor device A having a thickness of 200 nm. That is, a silicon nitride film 6 is formed instead of the silicon oxide film 5 on the tungsten silicide film 4 in the first conventional example. FIG. 19 shows a concentration profile of nitrogen (N) and arsenic (As) from the silicon nitride film 6 to the silicon substrate main body 1. Similar to FIG. 17, gate insulating film 2 (SiO2) and polycrystalline silicon film 3
The concentration of arsenic (As) is high at the interface with (polySi) and at the interface between tungsten silicide film 4 (WSix) and silicon nitride film 6 (Si3 N4). Therefore, the second conventional example has the same tendency as the first conventional example.

[0012]

As described above, in a structure in which a silicon oxide film 5 is formed on a refractory metal silicide film, for example, a tungsten silicide film 4, film peeling easily occurs due to the following reasons. Problem.

(1) The gate impurity implanted in the tungsten silicide film 4 in the above-described process is diffused and accumulated near the interface between the tungsten silicide film 4 and the silicon oxide film 5 by the subsequent heat treatment. Due to the accumulation of the gate impurities at the interface, the reaction between the tungsten in the tungsten silicide film 4 and the silicon in the silicon oxide film 5 is unlikely to occur, so that the adhesion between the two deteriorates and the film easily peels off. Become. Therefore, in order to avoid such film peeling, the injection amount of the gate impurity must be limited, and as a result,
The MOS type semiconductor device has a problem that the gate is depleted and the characteristics are deteriorated. In particular, when a p-type impurity is introduced into the gate, the boron concentration inside the polycrystalline silicon film 3 is reduced, so that in the case of a CMOS type semiconductor device, gate depletion becomes particularly large.

(2) The difference in thermal shrinkage between the tungsten silicide film 4 and the silicon oxide film 5 is large.
By the subsequent heat treatment, the tungsten silicide film 4
Stress concentrates on the interface between the silicon oxide film 5 and the silicon oxide film 5, and the film is easily peeled off.

(3) When ions of the gate impurity are directly implanted from above the tungsten silicide film 4, the surface of the tungsten silicide film 4 roughened by the implantation of the ions is exposed. Abnormal oxidation is likely to occur in the process.

These problems also exist when molybdenum silicide and titanium silicide are used instead of tungsten silicide, and also when silicon nitride film is used instead of silicon oxide film 5 as described above. Exists.

The present invention has been made in view of the above points, and has as its object to provide a semiconductor device and a method of manufacturing the same, in which a high-melting-point silicide film is provided above a semiconductor substrate; The present invention is to improve the adhesion between the refractory metal silicide and the insulating film by providing an insulating film made of a silicon compound on the substrate and making the composition of the insulating film a composition richer than that of the stoichiometric composition. .

[0018]

In order to achieve the above object, a means according to the first aspect of the present invention is provided as a semiconductor device, which is formed above a semiconductor substrate and has a high melting point metal such as tungsten, molybdenum or titanium. A refractory metal silicide film composed of a compound of silicon and a refractory metal silicide film formed on the refractory metal silicide film and composed of a compound of a silicon element and another element, wherein the content of the silicon element is stoichiometric In this configuration, a Si-rich insulating film having a higher content than the content based on the composition formula is provided.

According to a second aspect of the present invention, in the first aspect of the present invention, a polycrystalline silicon film is provided above the semiconductor substrate, and the refractory metal silicide film is formed on the polycrystalline silicon film. Shall be laminated. The polycrystalline silicon film and the refractory metal silicide film are configured to function integrally as electrodes and wiring.

A third aspect of the present invention is a method according to the first or second aspect, wherein the silicon-rich insulating film is made of the same compound as the Si-rich insulating film on the Si-rich insulating film. Is provided with a protective insulating film closer to the content based on the stoichiometric composition formula than the content of the silicon element in the Si-rich type insulating film.

According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the Si content of the Si-rich type insulating film is determined based on a stoichiometric composition formula as it goes upward. Are arranged so as to be continuously approached.

According to a fifth aspect of the present invention, in the first, second, third or fourth aspect of the present invention, the silicon-rich insulating film is made of silicon having a stoichiometric composition represented by SiO 2. The oxide film contains silicon element excessively.

A sixth aspect of the present invention is a method according to the first, second, third or fourth aspect of the present invention, wherein the Si-rich insulating film is formed of silicon having a stoichiometric composition represented by Si 3 N 4. The structure is such that the silicon element is excessively contained in the nitride film.

According to a seventh aspect of the present invention, in the above-described first, third, fourth, fifth, or sixth aspect, the semiconductor device includes at least one CMOS transistor. Then, a gate insulating film formed on the semiconductor substrate and a polycrystalline silicon film formed on the gate insulating film are provided. Further, the refractory metal silicide film is laminated on the polycrystalline silicon film, and the polycrystalline silicon film and the refractory metal silicide film
It is configured to function as a gate electrode of an OS transistor.

According to another aspect of the present invention, as a method of manufacturing a semiconductor device, after forming a refractory metal silicide film above a semiconductor substrate, a silicon element and another element are formed on the refractory metal silicide film. Consisting of a compound with the elements of
This is a method for forming a Si-rich insulating film in which the content of a silicon element is higher than the content based on the stoichiometric composition formula of the compound.

According to a ninth aspect of the present invention, in the method of the eighth aspect, the step of forming the Si-rich type insulating film is performed by a method in which the stoichiometric composition formula is represented by SiO 2 and the silicon element is excess. Is performed so as to form a Si-rich type silicon oxide film containing Si. The method further includes a step of implanting impurity ions into the refractory metal silicide film after forming the Si-rich silicon oxide film, and a step of oxidizing an upper portion of the silicon oxide film after the impurity ion implantation step. It is.

According to a tenth aspect of the present invention, in the method of the eighth aspect, the step of forming the Si-rich type insulating film is performed by a method in which the stoichiometric composition formula is represented by Si 3 N 4 and the silicon element is excessively added. Is performed so as to form a Si-rich silicon nitride film contained in the silicon nitride film. Furthermore, a method comprising the steps of: implanting impurity ions into the refractory metal silicide film after forming the Si-rich silicon nitride film; and nitriding the upper portion of the silicon nitride film after the impurity ion implantation process It is.

According to an eleventh aspect of the present invention, as a method of manufacturing a semiconductor device, a mixed gas of dichlorosilane and tungsten hexafluoride is thermally decomposed to form a tungsten silicide film on a semiconductor substrate. Process and then
While stopping the supply of tungsten hexafluoride gas, nitrous oxide gas is introduced, and a mixed gas of dichlorsilane gas and nitrous oxide gas is thermally decomposed to form a silicon oxide film on the tungsten silicide film. And a step of performing

According to a twelfth aspect of the present invention, as a method of manufacturing a semiconductor device, a mixed gas of dichlorosilane and tungsten hexafluoride is thermally decomposed to form a tungsten silicide film on a semiconductor substrate. Process and then
Stopping the supply of the tungsten hexafluoride gas, introducing ammonia gas, thermally decomposing a mixed gas of dichlorosilane gas and ammonia gas, and stacking a silicon nitride film on the tungsten silicide film. It is a method provided.

According to a thirteenth aspect of the present invention, in the method of the eighth aspect, the step of forming the high melting point metal silicide film is performed by thermally decomposing a mixed gas of dichlorosilane and tungsten hexafluoride. This is performed so that a tungsten silicide film is formed on a semiconductor substrate. Then, in the step of forming the Si-rich type insulating film, after forming the tungsten silicide film, the supply of the tungsten hexafluoride gas is stopped, and while the nitrous oxide gas is introduced, the dichlorsilane gas and the nitrous oxide gas are mixed. In this method, a mixed gas is thermally decomposed to stack a silicon oxide film on the tungsten silicide film.

According to a fourteenth aspect of the present invention, in the method of the eighth aspect, the step of forming the refractory metal silicide film is performed by thermally decomposing a mixed gas of dichlorsilane and tungsten hexafluoride. To form a tungsten silicide film on the semiconductor substrate. And Si
After the tungsten silicide film is formed, the supply of the tungsten hexafluoride gas is stopped, the ammonia gas is introduced, and the mixed gas of the dichlorosilane gas and the ammonia gas is thermally decomposed. And a method of stacking a silicon nitride film on the tungsten silicide film.

[0032]

According to the above construction, according to the first aspect of the present invention, Si
Since the silicon atoms in the rich-type insulating film have excess bonds, when impurities diffuse from the high-melting-point metal silicide film, they may aggregate at the interface between the high-melting-point metal silicide film and the Si-rich-type insulating film. Instead, it is diffused into the Si-rich insulating film. Therefore, the impurity concentration is kept low at the interface between the refractory metal silicide film and the Si-rich type insulating film, and the reaction between the refractory metal and silicon is performed without being hindered by the impurities. Further, when the content of the silicon element in the Si-rich insulating film increases, the composition approaches the composition of polycrystalline silicon, so that the difference in the thermal shrinkage between the Si-rich insulating film and the refractory metal silicide film is changed by chemical. The difference in thermal shrinkage between the insulating film having a composition based on the stoichiometric composition formula and the refractory metal silicide film is smaller than the difference. Therefore, the adhesion between the refractory metal silicide film and the Si-rich insulating film is good.

According to the second aspect of the present invention, the p-type impurity is converted from polycrystalline silicon to a high melting point metal silicide film, particularly in an electrode having a so-called polycide structure composed of a laminated film of polycrystalline silicon and a high melting point metal silicide film. However, in such a case, the impurities are easily diffused into the Si-rich type insulating film. It is avoided and the adhesion between the refractory metal silicide film and the Si-rich insulating film is also good.

According to the third aspect of the present invention, the protective insulating film has a composition close to the composition based on the stoichiometric composition formula.
Since there is little excess of the bonding of silicon atoms, the high melting point metal element in the high melting point metal silicide film and the impurities diffused from below are prevented from dispersing upward and the intrusion of impurities from the outside is prevented. . Therefore, the characteristics of each part of the semiconductor device are favorably maintained.

According to the fourth aspect of the present invention, in the Si-rich insulating film, the lower portion has a higher content of the silicon element and the upper portion has a higher content of the silicon element than the content based on the stoichiometric composition formula. As in the third aspect, good adhesion to the high melting point metal is maintained in the lower portion, and penetration and diffusion of impurities and the like are prevented in the upper portion.

According to the fifth aspect of the present invention, impurities such as arsenic and boron which are hardly diffused into the silicon oxide film having a composition based on the stoichiometric composition formula of silicon dioxide can be easily added to the Si-rich silicon oxide film. Spread. Therefore, the effects of the above inventions can be obtained.

According to the sixth aspect of the present invention, impurities such as arsenic, which hardly diffuses into the silicon nitride film having a composition based on the stoichiometric composition formula of silicon nitride, easily enter into the Si-rich silicon nitride film. Spread. Therefore, the effects of the above inventions can be obtained.

According to a seventh aspect of the present invention, in the case of a CMOS transistor, an n-channel MOS element contains an n-type impurity,
P-type impurities are respectively introduced into the p-channel MOS. At this time, the diffusion behavior in the refractory metal silicide film differs between the p-type impurity and the n-type impurity. In particular, the p-type impurity has a property of easily moving from the polycrystalline silicon film to the refractory silicide film. In addition, since the aggregation of impurities at the interface is avoided, the adhesion between the refractory metal silicide film and the Si-rich insulating film is good.

According to the eighth aspect of the present invention, the impurities diffused from the high melting point silicide film after the formation of the Si-rich insulating film are easily diffused into the Si-rich insulating film. Also,
Since the difference in thermal shrinkage between the Si-rich type insulating film and the refractory metal silicide film is relatively small, the stress applied to the interface during heat treatment or the like is also small. Therefore, the adhesion between the high melting point silicide film and the Si-rich insulating film is good, and the manufacture of the semiconductor device is easy.

According to the ninth or tenth aspect of the present invention, even when the impurity ions are implanted after forming the refractory metal silicide film due to the process, the Si-rich type silicon oxide film or the Si-rich type silicon nitride film is formed. Is implanted, impurity ions are implanted, so that the surface of the refractory metal silicide film is not roughened. Therefore, abnormal oxidation is less likely to occur in the subsequent heat treatment and oxidation steps.

According to the eleventh or twelfth aspect of the present invention, since the tungsten silicide film and the silicon oxide film or the silicon nitride film are formed of the same mixed gas containing dichlorosilane gas, the deposition temperatures of the two become substantially the same.
As a result, when heat treatment is performed, the difference in shrinkage between the two becomes smaller, and the adhesion between the two becomes better. Also, the same CVD
Since it becomes possible to continuously deposit in the apparatus, after the formation of the tungsten silicide film, before the formation of the silicon oxide film or the silicon nitride film, once the tungsten silicide film is exposed to the atmosphere, the abnormal oxidation of the tungsten silicide film often occurs. Will be blocked. Therefore, destruction of crystal grains due to abnormal oxidation of the tungsten silicide film is avoided.

According to the thirteenth or fourteenth aspect of the present invention, the tungsten silicide film which is a refractory metal silicide film is
Rich type insulating film (Si rich type silicon oxide film or Si
(Rich-type silicon nitride film), the aggregation of impurities at the interface is avoided, and the difference in thermal shrinkage is reduced.
Since the adhesion between the tungsten silicide film and the Si-rich insulating film is extremely good, and the crystal grains are prevented from being broken due to abnormal oxidation of the tungsten silicide film,
The characteristics of the semiconductor device are also good.

[0043]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) First, Embodiment 1 relating to a method of manufacturing a gate electrode of a MOS transistor will be described with reference to FIGS.

FIGS. 1A and 1B are cross-sectional views of a semiconductor device A in a manufacturing process of a gate electrode of a MOS transistor. First, as shown in FIG. 1A, a gate insulating film 2 (thickness: 5 to 16 nm) made of silicon dioxide (SiO2) is formed on a silicon substrate main body 1 by oxidation, and a polycrystalline silicon film is further formed thereon. 3 (thickness 50
To 200 nm). Then, ions of a gate impurity such as arsenic are implanted from above the polycrystalline silicon film 3 with an implantation energy of 40 keV and an implantation dose of 4 × 10 4.
Implantation is performed under a condition of ¹⁵ cm ⁻³ , and then, a tungsten silicide film 4 (50 to 200 nm in thickness) is laminated.

Next, as shown in FIG. 1B, the composition ratio (1) of the silicon element and the oxygen element based on the stoichiometric composition formula (SiO 2) is formed on the tungsten silicide film 4 by the CVD method. : 2) forming a Si-rich silicon oxide film 7 (50 to 200 nm thick) having a composition ratio higher than that of the silicon element. The composition formula of the Si-rich type silicon oxide film 7 is represented by SiOx1 (x1 = 1 to 1.5), and the silicon oxide film 5 in the first conventional example described above.
The composition ratio (1: 1) of the silicon element is higher than the composition ratio of the silicon element and the oxygen element, that is, the composition ratio (1: 2) of the silicon dioxide based on the stoichiometric composition formula SiO2 (1: 2).
To 1.5). Here, this Si-rich type silicon oxide film 7 is easily formed by appropriately setting the flow ratio of the introduced gas when performing the CVD process. For example, the flow rate of silane gas (SiH4) is set to 0.1 l.
/ Minute, and the flow rate of nitrous oxide gas (N2O) is 0.8
1 / min, and introduced into the reactor, respectively, at a pressure of 0.
When a gas is decomposed under the conditions of 3 Torr and a temperature of 840 ° C. to deposit a silicon oxide film, a silicon dioxide (SiO 2) film having a composition ratio of silicon element to oxygen element of 1: 2 grows. By lowering the flow rate of nitrogen gas (N2 O) to 0.4 to 0.6 l / min and performing CVD processing under the same other conditions as above, the composition ratio of silicon element to oxygen element Is 1 to 1.5
A rich silicon oxide film 7 grows.

Thereafter, patterning is performed in the same manner as in the conventional example, and the polycrystalline silicon film 3, the tungsten silicide film 4, and the Si-rich silicon oxide film 7 are sequentially etched to form a gate electrode. Further, in a subsequent step, the temperature is set to 850 ° C. to activate impurities, crystallize the refractory metal silicide film 4 and flatten the interlayer film.
A 950 ° C. heat treatment is applied.

FIG. 2 is a circuit diagram of the semiconductor device A according to the first embodiment.
The concentration profile of oxygen (O) and arsenic (As) from the i-rich type silicon oxide film 7 (SiOx1) to the silicon substrate body 1 (Si) is shown. Tungsten silicide film 4
(WSix) and Si-rich silicon oxide film 7 (SiO
The concentration of arsenic (As) at the interface with x1) is lower than the concentration of arsenic (As) in the same region of the conventional gate electrode (see FIG. 17 described above).

As described above, the tungsten silicide film 4
By forming a Si-rich silicon oxide film 7 (SiOx1; x1 = 1 to 1.5) having a high silicon element content thereon, the following effects can be obtained. That is, when a silicon oxide film having a composition ratio based on the stoichiometric composition formula SiO2 is formed on the tungsten silicide film, the silicon atoms and the oxygen atoms are stably bonded, The gate impurity diffused from the silicide film side hardly diffuses into the silicon oxide film, and aggregates at the interface between the tungsten silicide film and the silicon oxide film. On the other hand, in the structure of the first embodiment, the gate impurity diffused from below is
Bonding with silicon bonds not bonded to oxygen in the Si-rich silicon oxide film 7 becomes possible, and the concentration of gate impurities ubiquitous at the interface is reduced. Therefore, since tungsten and silicon tend to react near the interface, the adhesion between the tungsten silicide film 4 and the Si-rich silicon oxide film 7 is good. Further, since the difference in thermal shrinkage between the tungsten silicide film 4 and the Si-rich silicon oxide film 7 is small, the stress applied to the interface during heat treatment or the like is also small. Due to these effects, film peeling is less likely to occur.

Further, as a result, even if the concentration of the gate impurity implanted into the polycrystalline silicon film 3 becomes higher than the conventional case, the film peeling can be avoided. Therefore, the injection amount of the gate impurity is reduced to avoid the film peeling. No need to limit, MOS
Thus, depletion of the gate in the semiconductor device can be prevented.

Since the silicon content of the tungsten silicide film is not changed, there is no problem that the contact resistance with the wiring metal is increased.

In the first embodiment, the semiconductor device A equipped with a MOS transistor has been described as an example. However, in the semiconductor device equipped with a bipolar transistor, the high melting point metal of the present invention is applied to the emitter electrode of the bipolar transistor. By applying a stacked structure of a silicide film (and a polycrystalline silicon film) and a Si-rich silicon oxide film, it is not necessary to limit the amount of implanted emitter impurities, so that the current amplification factor of an npn transistor can be increased. effective.

Next, a case where boron ions as p-type impurities are implanted instead of arsenic as n-type impurities in the first embodiment will be described.

FIG. 3 shows that boron ions are implanted from above the polycrystalline silicon film 3 at an implantation energy of 10 keV and an implantation dose of 4 × 10 ¹⁵ cm ^{−3 in the} same steps and the same structure as in FIGS. 4 shows a concentration profile of boron (B) and oxygen (O) when implanted under the following conditions. That is, the tungsten silicide film 4 (WSix) and S
The concentration of boron (B) at the interface with the i-rich silicon oxide film 7 (SiOx1) does not rise at a peak as compared with the conventional case (see FIG. 20), and there is no aggregation of impurities at the interface. Is shown. In addition, since it is not necessary to reduce the dose of boron ions in order to alleviate aggregation at the interface as in the related art, the impurity concentration in the polycrystalline silicon film 3 is maintained at a sufficiently high level. Therefore, it can be seen that the same effect as in the first embodiment is obtained for the p-type impurity.

(Embodiment 2) Next, Embodiment 2 will be described with reference to FIGS.

FIG. 4 shows a cross-sectional structure of a semiconductor device A on which a MOS transistor is mounted according to the second embodiment. The structures and forming methods of the gate insulating film 2, the polycrystalline silicon film 3 and the tungsten silicide film 4 are the same as those of the above-described embodiment. 1 (FIG. 1
(See (a)).

In this embodiment, the Si-rich silicon oxide film 7 (SiO 2) having the same composition as that of the first embodiment is formed on the tungsten silicide film 4 by the CVD method.
x1; x1 = 1-1.5, thickness 30-100 nm), and further on the Si-rich silicon oxide film 7,
A protective silicon oxide film 9 (SiOx2; x2 = 1.2) composed of a silicon element and an oxygen element and having a composition closer to the stoichiometric composition of silicon dioxide SiO2 than the composition of the Si-rich silicon oxide film 7. 5-2, thickness 5
0 to 100 nm). As described in the first embodiment, the Si-rich silicon oxide film 7 and the protective silicon oxide film 9 can be easily formed by appropriately setting the flow rate of the introduced gas during the CVD process. For example, the flow rate of the silane gas is set to 0.1 l / min, and the flow rate of the nitrous oxide gas is set to 0.4 to 0.61 / min, and introduced into the reaction furnace, respectively, at a pressure of 0.3 Torr and a temperature of 840 ° C.
Gas is decomposed under the conditions described above, and the Si-rich silicon oxide film 7
Can be deposited, and under the same conditions, the flow rate of nitrous oxide gas is set to 0.
By increasing the rate to 6 to 0.8 l / min, the protective silicon oxide film 9 can be continuously laminated with the Si-rich silicon oxide film 7. That is, in the same deposition sequence, the lamination can be performed in one step by sequentially changing the flow rate of the sub-oxidizing gas.

Thereafter, the gate electrode is formed by patterning the mask and sequentially etching the polycrystalline silicon film 3, the tungsten silicide film 4, and the silicon oxide film 5. Further, in the subsequent steps, a heat treatment at 850 ° C. to 950 ° C. is applied for the purpose of activating the impurities, crystallizing the refractory metal silicide film 4 and flattening the interlayer film.

FIG. 5 shows a concentration profile of oxygen (O) and arsenic (As) from the protective silicon oxide film 9 (SiOx2) of the semiconductor device A according to the second embodiment to the silicon substrate body 1 (Si). Tungsten silicide film 4 (WS
ix) and the concentration of arsenic (As) at the interface between the Si-rich silicon oxide film 7 (SiOx1) is lower than in the conventional example. Further, the Si-rich silicon oxide film 7 (Si
Arsenic (As) does not aggregate at the interface between Ox1) and the protective silicon oxide film 9 (SiOx2).

Therefore, also in the second embodiment, similarly to the first embodiment, the tungsten silicide film 4
By forming the Si-rich silicon oxide film 7 (SiOx1; x1 = 1 to 1.5) having a high silicon element content, the adhesion between the tungsten silicide film 4 and the Si-rich silicon oxide film 7 is improved. Since the difference in heat shrinkage is small, the stress applied to the interface during heat treatment or the like is also small, so that film peeling can be prevented.

In addition, the second embodiment has the following effects. That is, on the Si-rich silicon oxide film 7, a protective silicon oxide film 9 (SiOx2; x2 = 1.x) having a composition close to the composition of the stoichiometric composition SiO2.
Since 5-2) is formed, diffusion of arsenic (As), which is a gate impurity, and tungsten, which is a refractory metal element, to the outside is prevented by the protective silicon oxide film 9. Further, in the protective silicon oxide film 9, since silicon and oxygen are bonded more stably than in the Si-rich type silicon oxide film 7, the tungsten silicide film 4 containing excessive oxygen or impurities from the outside is bonded. Intrusion is prevented. Therefore, it is possible to prevent the tungsten from being oxidized in the tungsten silicide film 4 to lower the resistance and to prevent impurities from being mixed in from the outside by ion implantation or the like to deteriorate the inside of the electrode or the gate oxide film. is there.

Third Embodiment Next, a third embodiment will be described with reference to FIGS.

FIGS. 6A and 6B show a cross-sectional structure in a manufacturing process of the semiconductor device A according to the third embodiment. The structure and formation of the gate insulating film 2, the polycrystalline silicon film 3, and the tungsten silicide film 4 are shown. The conditions are the same as in the first embodiment.

In this embodiment, as shown in FIG. 6, the composition based on the stoichiometric composition formula Si3 N4 is formed on the tungsten silicide film 4 by the CVD method.
Si-rich silicon nitride film 10 having a composition with a high silicon content (SiNy1; y1 = 0.8 to 1, thickness 50)
２００200 nm). The Si-rich silicon nitride film 10 can be formed by appropriately setting the flow ratio of the introduced gas during the CVD process. For example, the flow rate of dichlorosilane gas (SiH2 Cl2) is set to 0.07.
1 / min and the flow rate of ammonia gas (NH3) is 0.7
1 / min, respectively, and introduced into the reaction furnace at a pressure of 0.2
When the gas is decomposed under the conditions of 5 Torr and a temperature of 760 ° C. and a silicon nitride film is deposited, the composition ratio of silicon and nitrogen becomes 3
A Si3 N4 film, which is a pair 4, grows, but the ammonia gas (NH3) flow rate is reduced to 0.3 to 0.5 l / min. The composition ratio of Si and nitrogen N is 1: 0.8-
1, a Si-rich silicon nitride film 10 is deposited.

Thereafter, similarly to the conventional example, the polycrystalline silicon film 3, the tungsten silicide film 4, and the Si-rich silicon nitride film 10 are sequentially selectively etched to form a gate electrode. Then, a heat treatment at 850 ° C. to 950 ° C. is applied for the purpose of activating impurities or the like.

FIG. 7 shows a semiconductor device A according to the third embodiment.
(N) and arsenic (As) from the Si-rich type silicon nitride film 10 (SiNy1) to the silicon substrate 1 (Si).
3 shows a density profile of the sample. The tungsten silicide film 4 (WSix) and the Si-rich silicon nitride film 10 (S
The concentration of arsenic (As) at the interface with iNy1) is lower than in the conventional example.

Accordingly, in the third embodiment, the arsenic in the tungsten silicide film 4 is formed by forming the Si-rich silicon nitride film 10 (SiNy1; y1 = 0.8 to 1) on the tungsten silicide film 4. A gate impurity such as (As) can be bonded to a bond of silicon not bonded to nitrogen in the Si-rich silicon nitride film 10. Therefore, the tungsten silicide film 10
, The gate impurity easily diffuses into the Si-rich silicon nitride film 10, and the concentration of the gate impurity accumulated at the interface decreases. Therefore, since tungsten and silicon easily react near the interface, the adhesion between the tungsten silicide film 4 and the Si-rich silicon nitride film 10 is improved, and the tungsten silicide film 4 and the Si-rich silicon nitride film 10 are improved. Therefore, the stress at the interface is reduced. Due to these effects, film peeling is less likely to occur.

As a result, similarly to the first embodiment, M
Deterioration of characteristics due to gate depletion in an OS type semiconductor device is prevented, and npn
The current gain of the transistor can be increased.

(Embodiment 4) Next, Embodiment 4 will be described with reference to FIGS.

FIG. 8 is a sectional view of a semiconductor device A according to the fourth embodiment. On the silicon substrate body 1, a gate insulating film 2, a polycrystalline silicon film 3, and a tungsten silicide film 4 are formed under the same conditions as in the first embodiment.

Here, in this embodiment, on the tungsten silicide film 4, a Si-rich silicon nitride film 10 (thickness of 50 to 200 n
m, SiNy1; y1 = 0.8-1).
On the i-rich silicon nitride film 10, the composition ratio of silicon element and nitrogen element is
More specifically, the protective silicon nitride film 12 (SiNy2; y2 = 1 to 1) having a composition ratio closer to the stoichiometric composition formula Si3 N4.
33, and a thickness of 50 to 100 nm). The Si-rich silicon nitride film 10 and the protective silicon nitride film 1
2 is easily formed by appropriately setting the flow rate of the introduced gas during the CVD process. For example, the flow rate of dichlorosilane gas is set to 0.07 l / min, and the flow rate of ammonia gas is set to 0.3 to 0.5 l / min, and introduced into the reaction furnace, at a pressure of 0.25 Torr and a temperature of 760 ° C.
After forming the silicon nitride film by decomposing the gas under the conditions of
By changing only the flow rate of the ammonia gas to 0.5 to 0.7 l / min, it can be formed continuously in one step.

Thereafter, patterning is performed, and the polycrystalline silicon film 3, the tungsten silicide film 4, and the silicon oxide film 5 are sequentially etched to form a gate electrode. At 8
A heat treatment at 50C to 950C is applied.

FIG. 9 shows a concentration profile of nitrogen (N) and arsenic (As) from the protective silicon nitride film 12 (SiNy2) to the silicon substrate body 1 (Si) of the semiconductor device A in the fourth embodiment. Tungsten silicide film 4
(WSix) and Si-rich silicon nitride film 10 (Si
The arsenic concentration at the interface with Ny1) is lower than in the conventional example.

Therefore, in the fourth embodiment, as in the third embodiment, the Si
Since the rich silicon nitride film 10 is formed, the same effects as those of the third embodiment can be obtained. Further, since the protective silicon nitride film 12 is formed on the Si rich silicon nitride film 10, The following effects can be obtained.

That is, the protective silicon nitride film 12 prevents gate impurities such as arsenic (As) and the tungsten diffused from the tungsten silicide film 4 from diffusing to the outside. Further, the protective silicon nitride film 12
In the inside, since silicon and nitrogen are bonded more stably than in the Si-rich silicon nitride film 10, tungsten is oxidized by diffusion of excessive oxygen from the outside into the tungsten silicide film 4, and the resistance is reduced. In addition, it is possible to prevent the lowering and to prevent impurities from being mixed from the outside during the ion implantation or the like and to deteriorate the inside of the electrode or the gate oxide film.

(Embodiment 5) Next, Embodiment 5 will be described with reference to FIG.

First, as shown in FIG. 10A, a gate insulating film 2 (having a thickness of 5 nm to 16 nm) is formed on a silicon substrate main body 1 by oxidation under the same conditions as in the first embodiment. Polycrystalline silicon film 3 (thickness 50 to 200 n
m) and the tungsten silicide film 4 (thickness 50 to 2)
00 nm). Then, the Si-rich silicon oxide film 7 (thickness: 20 to 5) is formed on the tungsten silicide film 4 by the CVD method under the same conditions as in the first embodiment.
0 nm, SiOx1; x1 = 1 to 1.5).

Further, as shown in FIG. 10B, ions of a gate impurity such as arsenic (As) are implanted above the silicon substrate under the conditions of an implantation energy of 40 keV and an implantation dose of 4 × 10 ¹⁵ cm ^-3. Inject from

Subsequently, as shown in FIG.
The surface of the rich silicon oxide film 7 is oxidized in an electric furnace at a furnace temperature of 850 ° C. for 20 minutes, for example, to increase the oxygen content. That is, the upper part of the Si-rich silicon oxide film is changed to a protective silicon oxide film 9 (SiOx2; x2 = 1.5-2, thickness 10-30 nm) having a composition close to the stoichiometric composition SiO2. At this time, the implanted gate impurity diffuses into the polycrystalline silicon film 3 and is activated, and the tungsten silicide film 4 and the Si-rich silicon oxide film 7 whose structures are disturbed by the ion implantation are reconfigured. .

Thereafter, patterning is performed, and the polycrystalline silicon film 3, the tungsten silicide film 4, the Si-rich silicon oxide film 7, and the protective silicon oxide film 9 are sequentially etched to form a gate electrode. Further, in the subsequent steps, 850 is used for the purpose of activation of impurities and the like.
A heat treatment at between ℃ and 950 ℃ is applied.

Although not shown in the fifth embodiment, the concentration profiles of oxygen and arsenic from the protective silicon oxide film 9 of the semiconductor device A to the silicon substrate main body 1 are the same as those of the second embodiment shown in FIG. Is the same as That is, the concentration of arsenic at the interface between the tungsten silicide film 4 and the Si-rich silicon oxide film 7 is lower than in the conventional example.

Therefore, in the fifth embodiment, the same effects as those of the first and second embodiments can be obtained, and the following specific effects can be obtained.

That is, when a gate impurity is directly implanted into the surface of the tungsten silicide film 4 by ion implantation, conventionally, since the surface of the tungsten silicide film 4 which has been ion-implanted and roughened is exposed, heat treatment or There has been a problem that abnormal oxidation easily occurs in the oxidation process. On the other hand, in Example 5, impurities are introduced into the refractory metal silicide film by the ion implantation method in a state where the surface of the tungsten silicide film 4 is covered with the Si-rich type silicon oxide film 7. Abnormal oxidation is less likely to occur during the heat treatment and oxidation steps. Therefore, the quality of the semiconductor device A can be improved.

(Embodiment 6) Next, Embodiment 6 will be described with reference to FIG.

FIGS. 11A to 11C are cross-sectional views showing the steps of manufacturing a semiconductor device A equipped with a MOS transistor according to the sixth embodiment. First, as shown in FIG. 11A, a gate insulating film 2, a polycrystalline silicon film 3, and a tungsten silicide film 4 are laminated on a silicon substrate body 1 under the same conditions as in the second embodiment. Further, on the tungsten silicide film 4, the Si-rich silicon nitride film 10 (SiNy1; y1 = 0.8-1 and the thickness 20-30) is formed on the tungsten silicide film 4 by the CVD method under the same conditions as in the second embodiment.
nm). This Si-rich type silicon nitride film 1
0 is easily formed by appropriately setting the flow rate of the introduced gas in the same manner as in the third embodiment during the CVD process.

Next, as shown in FIG. 11 (b), ions of a gate impurity such as arsenic
0 keV and an implantation dose of 4 × 10 ¹⁵ cm ⁻³ ,
It is implanted from above the silicon substrate.

Subsequently, as shown in FIG.
The surface portion of the rich silicon nitride film 10 is nitrided in an electric furnace at a furnace temperature of 850 ° C. for 20 minutes, for example, to increase the content of the nitrogen element. That is, the Si-rich silicon nitride film 1
0 is formed on the silicon nitride film 12 (SiNy2; y2 = 1.about.1) having a composition close to the stoichiometric composition formula Si3 N4 film.
33, thickness 10-20 nm). At this time, the implanted gate impurities are diffused and activated in the polycrystalline silicon film 3, and the tungsten silicide film 4 and the silicon nitride film 10 whose structures are disturbed by the ion implantation are reconfigured.

Thereafter, patterning is performed to form the polycrystalline silicon film 3, the tungsten silicide film 4, the Si-rich silicon nitride film 10, and the protective silicon nitride film 12
Are sequentially etched to form a gate electrode. Further, in the subsequent steps, a heat treatment at 850 ° C. to 950 ° C. is performed for activation of impurities and the like.

Although not shown, the nitrogen and arsenic concentration profiles from the protective silicon nitride film 12 of the semiconductor device A to the silicon substrate body 1 in the sixth embodiment are the same as those in the fourth embodiment shown in FIG. . That is, the tungsten silicide film 4 and the silicon nitride film 1
The arsenic concentration at the interface with zero is lower than in the conventional example.

Therefore, in the sixth embodiment, not only the same effects as in the fourth embodiment but also the following specific effects can be obtained.

That is, similarly to the fifth embodiment, when a gate impurity is directly implanted into the surface of the tungsten silicide film 4 by the ion implantation method, conventionally, the surface of the tungsten silicide film 4 which is roughened by the ion implantation is exposed. Therefore, there has been a problem that abnormal oxidation easily occurs in the subsequent heat treatment and oxidation steps. However, when the surface of the tungsten silicide film 4 is covered with the Si-rich type silicon oxide film 10, impurity ions are high. Since it is injected into the melting point metal silicide film, abnormal oxidation hardly occurs in the subsequent heat treatment and oxidation steps.

(Embodiment 7) Next, Embodiment 7 will be described with reference to FIGS.

FIG. 12 is a sectional view of a semiconductor device A equipped with a MOS transistor according to the seventh embodiment. First, similarly to the first embodiment, after a gate insulating film 2 and a polycrystalline silicon film 3 are formed on a silicon substrate body 1, ions of a gate impurity such as arsenic are implanted (the implantation conditions are the same as in the first embodiment). Same as 1).

After forming the tungsten silicide film 4 (thickness: 50 to 200 nm), a composition having a higher silicon element content than the composition based on the stoichiometric composition SiO 2 is formed on the tungsten silicide film 4. Are stacked in the same CVD apparatus, and in this case, both are stacked using dichlorosilane gas (SH2 Cl2) as a part of the raw material.

As a method of forming this laminated film, first, as shown in FIG. 13, dichlorosilane gas (SH
2 Cl 2) and tungsten hexafluoride gas (WF6) by thermal decomposition to form a tungsten silicide film 4 having a thickness of 50%.
It is formed at a furnace temperature of 0 ° C. to 600 ° C. (time t1 in the figure)
Until). Next, with the wafer remaining in the furnace, the tungsten hexafluoride gas (WF6) is shut off, and simultaneously the furnace temperature is raised from 650 DEG C. to 700 DEG C., and the nitrous oxide gas (N2 O) is reduced to 0.4%. At a flow rate of about 0.61 / min (time t2 in the figure), the composition ratio of silicon and oxygen is 1: 1.
A Si-rich silicon oxide film 7 of .about.1.5 is deposited. Although not shown in FIG. 13, dichlorosilane gas (SH2 Cl2) is used for forming the tungsten silicide film 4 and the Si-rich silicon oxide film 7.
In any of the steps of depositing, is supplied into the furnace.

Thereafter, patterning is performed, and the polycrystalline silicon film 3, the tungsten silicide film 4, and the Si-rich silicon oxide film 7 are sequentially etched to form a gate electrode. Further, in the subsequent steps, a heat treatment at 850 ° C. to 950 ° C. is performed for activation of impurities and the like.

Thus, the tungsten silicide film 4
By forming the silicon-rich silicon oxide film 7 and the mixed gas containing the same dichlorosilane gas, the deposition temperatures of both films can be made substantially the same. As a result, the difference in thermal shrinkage between the two shrinks, and the stress applied to the interface during heat treatment or the like also decreases, so that film peeling can be prevented.

Further, the tungsten silicide film 4 and S
By continuously depositing the i-rich type silicon oxide film 7 in the same CVD apparatus, before the tungsten silicide film 4 is crystallized and the grains grow, the surface can be covered with the insulating film without being exposed to the air. In addition, abnormal oxidation of the tungsten silicide film 4 can be prevented.

(Eighth Embodiment) Next, an eighth embodiment will be described with reference to FIGS.

FIG. 14 is a sectional view of a semiconductor device A equipped with a MOS transistor according to the eighth embodiment. First,
After forming the gate insulating film 2 and the polycrystalline silicon film 3 on the silicon substrate main body 1 in the same manner as in the first embodiment, ions of a gate impurity such as arsenic are implanted (the implantation conditions are the same as in the first embodiment). the same).

After forming the tungsten silicide film 4 (thickness: 50 to 200 nm), the content of the silicon element on the tungsten silicide film 4 is higher than that of the composition based on the stoichiometric composition formula Si3 N4. A Si-rich type silicon nitride film 10 having a composition is laminated in the same CVD apparatus. In this case, both are laminated using dichlorosilane gas (SiH2 Cl2) as a part of the raw material.

As a method for forming this laminated film, first, as shown in FIG. 15, dichlorosilane gas (Si
A tungsten silicide film 4 is formed at a furnace temperature of 500 ° C. to 600 ° C. by thermal decomposition of a mixed gas of H 2 Cl 2) and tungsten hexafluoride gas (WF 6) (until time t3 in the figure). Next, with the wafer remaining in the furnace,
At the same time as shutting off the tungsten hexafluoride gas (WF6), the temperature in the furnace is raised to 650 DEG C. to 700 DEG C., and ammonia gas (NH3) is introduced at a flow rate of 0.3 to 0.51 / min. From time t4), the Si-rich silicon nitride film 1 having a composition ratio of silicon to oxygen of 1: 0.8-1.
Grow 0. The dichlorsilane gas is continuously supplied into the furnace during the step of depositing the tungsten silicide film 4 and the step of depositing the Si-rich silicon nitride film 10.

Thereafter, patterning is performed, and the polycrystalline silicon film 3, the tungsten silicide film 4, and the Si-rich silicon nitride film 10 are sequentially etched to form a gate electrode. Further, in the subsequent steps, a heat treatment at 850 ° C. to 950 ° C. is performed for activation of impurities and the like.

Thus, the tungsten silicide film 4
And the Si-rich silicon nitride film 10 are formed from a mixed gas containing the same dichlorosilane gas (SiH2 Cl2), whereby the deposition temperatures of both films can be made substantially the same, and as a result, the heat treatment can be performed. , The stress applied to the interface during heat treatment or the like is reduced, and film peeling is less likely to occur.

Further, the tungsten silicide film 4 and S
By continuously depositing the i-rich type silicon nitride film 10 in the same CVD apparatus, the surface can be covered with an insulating film without being exposed to the air before the tungsten silicide film 4 is crystallized and grains grow. Thus, abnormal oxidation of the tungsten silicide film 4 can be prevented.

[0106]

As described above, according to the first aspect of the present invention, as a semiconductor device, a silicon element and another compound are formed on a refractory metal silicide film, and the content of the silicon element is stoichiometric. Is configured to deposit a Si-rich type insulating film higher than the content based on the stoichiometric composition formula, so that impurities diffused from the refractory metal silicide film are diffused to the insulating film side without aggregating at the interface. In addition to promoting the reaction between the refractory metal and silicon at the interface, the difference in thermal shrinkage between the Si-rich insulating film and the refractory metal silicide film can be reduced. The adhesion with the rich type insulating film can be improved.

According to the second aspect of the present invention, in the first aspect of the present invention, the refractory metal silicide film has a so-called polycide structure provided on the polycrystalline silicon film.
The adhesion between the polycide film and the underlying insulating film can be improved while maintaining the characteristics of high conductivity of the polycide film and good matching with the base.

According to the third aspect of the present invention, in the first or second aspect of the present invention, the silicon element content on the Si-rich type insulating film is close to the content based on the stoichiometric composition formula. Is formed so that the high melting point metal element in the high melting point metal silicide film and the impurities diffused from below can be prevented from dissipating upward and from entering the impurities from outside. The characteristics of each part of the semiconductor device can be improved.

According to a fourth aspect of the present invention, in the semiconductor device according to the first or second aspect, as the Si content of the Si-rich insulating film increases toward the upper portion, the Si content is continuously increased based on the stoichiometric composition formula. S
In the lower part of the i-rich type insulating film, it is possible to prevent invasion and diffusion of impurities and the like in the upper part while maintaining good adhesion to the high melting point metal.

According to the invention of claim 5, claims 1, 2,
In the semiconductor device described in 3 or 4, the Si-rich insulating film is a silicon oxide film whose stoichiometric composition is represented by SiO2, so that the silicon oxide film having a composition based on the stoichiometric composition is Impurities such as arsenic and boron, which are difficult to diffuse, can be easily diffused into the Si-rich silicon oxide film, so that effects such as improvement in adhesion can be effectively exhibited.

According to the invention of claim 6, according to claims 1, 2, 2
In the semiconductor device described in 3 or 4, the Si-rich type insulating film is a silicon nitride film whose stoichiometric composition is represented by Si3 N4, so that a silicon nitride film having a composition based on the stoichiometric composition is used. Can easily diffuse impurities such as arsenic and boron, which are hardly diffused, into the Si-rich silicon nitride film, so that effects such as improvement in adhesion can be effectively exhibited.

According to the invention of claim 7, claims 1, 3 and
In the inventions of 4, 5, and 6, since the semiconductor element is a CMOS transistor and a polycide electrode structure including a polycrystalline silicon film and a high melting point silicide film is employed, p-type impurities and n-type impurities are used as gate impurities. Also in the structure to be introduced, aggregation of the gate impurity at the interface can be prevented, and therefore, the adhesion between the polycide film and the upper insulating film can be improved.

According to the invention of claim 8, as a method of manufacturing a semiconductor device, a refractory metal silicide film is formed above a semiconductor substrate and a Si-rich type insulating film is formed thereon. Impurities diffused from below after the formation of the rich-type insulating film are easily diffused into the Si-rich poly-insulating film, and the refractory metal silicide film and the Si
By reducing the difference in heat shrinkage from the rich insulation film,
The adhesion between the two can be improved, and therefore, the manufacture of the semiconductor device can be facilitated.

According to the ninth aspect of the present invention, in the eighth aspect of the present invention, a silicon oxide film having a stoichiometric composition represented by SiO 2 is formed as the Si-rich insulating film, and the silicon oxide film is formed. After being formed, impurity ions are implanted into the refractory metal silicide film, and then the upper portion of the silicon oxide film is oxidized, so that the surface state of the refractory metal silicide film can be maintained well without being roughened. Therefore, abnormal oxidation in the subsequent heat treatment and oxidation steps can be prevented.

According to the tenth aspect, the eighth aspect is provided.
In the invention, a silicon nitride film having a stoichiometric composition formula of Si3 N4 is formed as a Si-rich type insulating film, and after forming the silicon nitride film, impurity ions are implanted into the refractory metal silicide film; Thereafter, since the upper portion of the silicon nitride film is nitrided, the surface state of the refractory metal silicide film can be favorably maintained without roughening, thereby preventing abnormal oxidation in later heat treatment and oxidation steps. be able to.

According to the eleventh aspect of the present invention, as a method of manufacturing a semiconductor device, a mixed gas of dichlorsilane and tungsten hexafluoride is thermally decomposed to form a tungsten silicide film, and thereafter, a tungsten hexafluoride gas is formed. While the supply of nitrogen was stopped, a nitrous oxide gas was introduced and a silicon oxide film was laminated on the tungsten silicide film, so that the difference in the thermal contraction rate between the tungsten silicide film and the silicon oxide film was reduced and the tungsten oxide was reduced. Abnormal oxidation of the silicide film can be prevented.

According to a twelfth aspect of the present invention, as a method of manufacturing a semiconductor device, a mixed gas of dichlorosilane and tungsten hexafluoride is thermally decomposed to form a tungsten silicide film, and then a tungsten hexafluoride gas is formed. While the supply of oxygen was stopped, ammonia gas was introduced and the silicon nitride film was laminated on the tungsten silicide film, so that the difference in thermal contraction rate between the tungsten silicide film and the silicon nitride film was reduced and the tungsten silicide film was reduced. Abnormal oxidation can be prevented.

According to the thirteenth aspect, the eighth aspect is provided.
In the invention, the mixed gas of dichlorsilane and tungsten hexafluoride is thermally decomposed to form a tungsten silicide film which is to be a high-melting metal silicide film, and then the supply of the tungsten hexafluoride gas is stopped. Nitrous oxide gas was introduced and Si was deposited on the tungsten silicide film.
Since the Si-rich type silicon oxide film serving as the rich-type insulating film is laminated, the tungsten silicide film can be obtained in addition to the effect of improving the adhesion by the Si-rich type insulating film and the effect of improving the adhesion by making the deposition temperature uniform. The effect of preventing abnormal oxidation can be obtained.

According to the fourteenth aspect, the eighth aspect is provided.
In the invention, the mixed gas of dichlorsilane and tungsten hexafluoride is thermally decomposed to form a tungsten silicide film which is to be a high-melting metal silicide film, and then the supply of the tungsten hexafluoride gas is stopped. Ammonia gas is introduced and Si is deposited on the tungsten silicide film.
Since a silicon nitride film serving as a rich-type insulating film is laminated, the effect of improving the adhesion by the Si-rich-type insulating film and the effect of improving the adhesion by making the deposition temperature uniform are improved. An effect of preventing oxidation can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a semiconductor device in a manufacturing process of a gate electrode of the semiconductor device according to the first embodiment.

FIG. 2 is a diagram showing a profile of an n-type impurity concentration in Example 1.

FIG. 3 is a diagram showing a profile of a p-type impurity concentration in Example 1.

FIG. 4 is a cross-sectional view of the semiconductor device in a manufacturing step of a gate electrode of the semiconductor device according to the second embodiment.

FIG. 5 is a view showing a profile of an impurity concentration in Example 2.

FIG. 6 is a sectional view of a semiconductor device according to a third embodiment.

FIG. 7 is a view showing a profile of an impurity concentration in Example 3.

FIG. 8 is a sectional view of a semiconductor device according to a fourth embodiment.

FIG. 9 is a diagram showing a profile of an impurity concentration in Example 4.

FIG. 10 is a cross-sectional view of a semiconductor device in a manufacturing step of the semiconductor device according to the fifth embodiment.

FIG. 11 is a cross-sectional view of a semiconductor device in a manufacturing step of the semiconductor device of the sixth embodiment.

FIG. 12 is a sectional view of a semiconductor device according to a seventh embodiment.

FIG. 13 is a diagram showing a change over time in a deposition temperature and a gas flow rate in the manufacturing process of the semiconductor device of Example 7.

FIG. 14 is a sectional view of a semiconductor device according to an eighth embodiment.

FIG. 15 is a diagram showing a change over time in a deposition temperature and a gas flow rate in the manufacturing process of the semiconductor device of Example 8.

FIG. 16 is a sectional view of a semiconductor device according to a first conventional example.

FIG. 17 is a diagram showing a profile of an impurity concentration in the first conventional example.

FIG. 18 is a sectional view of a semiconductor device according to a second conventional example.

FIG. 19 is a diagram showing an impurity concentration profile in a second conventional example.

FIG. 20 is a diagram showing an impurity concentration profile when a p-type impurity is implanted instead of an n-type impurity in the conventional example.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 silicon substrate main body 2 gate oxide film 3 polycrystalline silicon film 4 tungsten silicide film (refractory metal silicide film) 5 silicon oxide film 6 silicon nitride film 7 Si-rich silicon oxide film (Si-rich insulating film) 9 protective silicon Oxide film (protective insulating film) 10 Si-rich silicon nitride film (Si-rich insulating film) 12 Protective silicon nitride film (protective insulating film)

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-42175 (JP, A) JP-A-2-218164 (JP, A) JP-A-2-250319 (JP, A) JP-A-3-42 19341 (JP, A) JP-A-4-61167 (JP, A)

Claims (14)

(57) [Claims] 1. A refractory metal silicide film formed above a semiconductor substrate and made of a compound of silicon and a refractory metal such as tungsten, molybdenum, and titanium; and a refractory metal silicide film formed on the refractory metal silicide film. A semiconductor device comprising: a compound of an element and another element; and a Si-rich insulating film having a silicon element content higher than a content based on a stoichiometric composition formula of the compound. 2. The semiconductor device according to claim 1, further comprising a polycrystalline silicon film formed above said semiconductor substrate, wherein said high melting point metal silicide film is laminated on said polycrystalline silicon film. A polycrystalline silicon film and a refractory metal silicide film integrally function as an electrode and a wiring. 3. The semiconductor device according to claim 1, wherein the silicon-rich insulating film is formed on the Si-rich insulating film and is made of the same compound as the Si-rich insulating film. A semiconductor device comprising a protective insulating film having a content based on a stoichiometric composition formula rather than a silicon element content of the film. 4. The semiconductor device according to claim 1, wherein the Si content of the Si-rich insulating film continuously approaches a content based on a stoichiometric composition formula as it goes upward. A semiconductor device characterized by being performed. 5. The semiconductor device according to claim 1, wherein said Si-rich insulating film has a stoichiometric composition formula of SiO 2.
2. A semiconductor device comprising a silicon oxide film represented by 2 and an excess of silicon element. 6. The semiconductor device according to claim 1, wherein the Si-rich insulating film has a stoichiometric composition formula of Si 3.
A semiconductor device comprising a silicon nitride film represented by N4 containing an excessive amount of silicon element. 7. The semiconductor device according to claim 1, wherein the semiconductor device includes at least one CMOS transistor, and a gate insulating film formed on the semiconductor substrate; A polycrystalline silicon film formed on the gate insulating film, wherein the refractory metal silicide film is laminated on the polycrystalline silicon film, and the polycrystalline silicon film and the refractory metal silicide are The membrane is
A semiconductor device, which functions as a gate electrode of the CMOS transistor. 8. A step of forming a refractory metal silicide film above a semiconductor substrate; and forming a refractory metal silicide film on the refractory metal silicide film by a compound of a silicon element and another element. Forming a Si-rich insulating film having a content higher than the content based on the stoichiometric composition formula of the compound. 9. The method of manufacturing a semiconductor device according to claim 8, wherein in the step of forming the Si-rich type insulating film, the stoichiometric composition formula is represented by SiO 2, and the Si-rich insulating film excessively contains a silicon element. Implanting impurity ions into the refractory metal silicide film after forming the Si-rich silicon oxide film; and forming the silicon oxide film after the impurity ion implantation process. Oxidizing the upper part of the semiconductor device. 10. The method of manufacturing a semiconductor device according to claim 8, wherein in the step of forming the Si-rich insulating film, the stoichiometric composition formula is represented by Si3 N4 and the Si-rich insulating film excessively contains a silicon element. Implanting impurity ions into the refractory metal silicide film after forming the Si-rich silicon nitride film, and forming the silicon nitride film after the impurity ion implantation process. And a step of nitriding the upper part. 11. A step of thermally decomposing a mixed gas of dichlorsilane and tungsten hexafluoride to form a tungsten silicide film on a semiconductor substrate, and then stopping supply of the tungsten hexafluoride gas. Introducing a nitrous oxide gas, thermally decomposing a mixed gas of a dichlorsilane gas and a nitrous oxide gas, and stacking a silicon oxide film on the tungsten silicide film. Device manufacturing method. 12. A method for manufacturing a semiconductor device comprising a semiconductor element disposed in a semiconductor substrate, wherein a mixed gas of dichlorosilane and tungsten hexafluoride is thermally decomposed to form tungsten on the semiconductor substrate. A step of forming a silicide film, and thereafter, while stopping the supply of the tungsten hexafluoride gas, introducing an ammonia gas, and thermally decomposing a mixed gas of a dichlorosilane gas and an ammonia gas to form a film on the tungsten silicide film. Laminating a silicon nitride film on the semiconductor device. 13. The method of manufacturing a semiconductor device according to claim 8, wherein the step of forming the refractory metal silicide film comprises thermally decomposing a mixed gas of dichlorosilane and tungsten hexafluoride to form a film on the semiconductor substrate. The process of forming a tungsten silicide film is performed. In the step of forming a Si-rich type insulating film, after the tungsten silicide film is formed, the supply of the tungsten hexafluoride gas is stopped, and the nitrous oxide gas is introduced. A method of manufacturing a semiconductor device, wherein a mixed gas of chlorsilane gas and nitrous oxide gas is thermally decomposed to stack a silicon oxide film on the tungsten silicide film. 14. The method for manufacturing a semiconductor device according to claim 8, wherein the step of forming the refractory metal silicide film comprises thermally decomposing a mixed gas of dichlorosilane and tungsten hexafluoride to form a film on the semiconductor substrate. The process of forming a tungsten silicide film is performed. After forming the tungsten silicide film, the supply of the tungsten hexafluoride gas is stopped, while the ammonia gas is introduced and the dichlorosilane gas is formed. A method for manufacturing a semiconductor device, comprising: thermally decomposing a mixed gas of hydrogen and ammonia gas to stack a silicon nitride film on the tungsten silicide film.