JP3250543B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a semiconductor device in which silicide is formed in a shallow junction layer on the surface of a semiconductor substrate.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of LSIs (large-scale integrated circuits), a film formation technique capable of forming a low-resistance layer at the bottom of a contact forming a connection part in a wiring and realizing good coverage on a semiconductor surface. Is being considered. Until now, various materials and film formation methods have been proposed. Among them, TiSi ₂ (titanium silicide)
The film is attracting attention as a promising material because of its low resistance, stable electrical properties even at high temperatures, and good compatibility with the TiN (titanium nitride) film used as a barrier film with metal wiring .

At present, methods for forming a TiSi2 film include a sputtering method and a plasma CVD (vapor phase growth) method. Here, a salicide process is generally used for forming a TiSi ₂ film by a sputtering method. This is formed by the following process flow. (1) Pattern the polycrystalline silicon to be the gate electrode wiring.

(2) Ti is formed on the entire surface of the substrate, and S is formed by heat treatment.
Ti in contact with i is silicided by an alloying reaction. (3) Ti which has not reacted with Si on the insulating film is selectively removed. Through the processes (1) to (3), a TiSi ₂ film is formed. This makes it possible to silicide the gate electrode wiring and the surface of the impurity diffusion layer simultaneously and in a self-aligned manner, thereby reducing the resistance.

However, in recent years, due to the increase in aspect ratio due to miniaturization, the above-mentioned TiSi ₂
In the film formation method, a sufficient thickness of TiSi
It is becoming impossible to form two layers. In processes with design rules of 0.13 μm or less, plasma CVD
The formation method of the TiSi2 layer by the method is becoming effective.

[0006] Compared to the sputtering method, the CVD method can form a film having excellent step coverage even on uneven portions.
Further, selective growth utilizing a reaction difference due to a difference in the material of a base for forming a film is also possible. For example, the common TiSi ₂
The plasma CVD of the film is performed using Ar / H ₂ / TiCl ₄ (argon / hydrogen /
In a (titanium / chlorine) plasma atmosphere, a Ti film is deposited while heating a silicon (Si) substrate to about 600 ° C. At this time, the Ti film-forming species generated in the plasma cause a silicidation reaction with the exposed underlying Si, and the TiSi
_Two layers are formed.

The above-described method for forming a TiSi ₂ film by the plasma CVD method also has some problems. That is, the substrate Si is consumed during the silicidation reaction, and the problem of junction leakage occurs for a shallow junction on the surface of the substrate Si because the formed silicide film penetrates this junction.

[0008] In particular, the problem of penetration through the junction in the plasma CVD method is a problem of TiSi ₂ consumed during the silicidation reaction.
Some are caused by the material itself, and others are caused by an etching effect by chlorine-based etching species generated by decomposition of the source gas TiCl ₄ gas in plasma. For this reason, the amount of Si consumed is large, and this problem of junction leakage is extremely serious for a shallow junction. Further, since etching occurs during the silicidation reaction, it is difficult to form the TiSi ₂ film uniformly and with good reproducibility.

[0009]

As described above, the formation of the TiSi2 film by the conventional plasma CVD method consumes the underlying Si due to the silicidation reaction and the etching reaction. Therefore, using the conventional method, the TiSi ₂
When a film is formed, the shallow junction is broken by the silicide that has penetrated, and a leak occurs. Also,
It is extremely difficult to form a uniform thin TiSi ₂ film because of the above-mentioned etching effect.

The present invention has been made under such a background. By controlling the temperature at which chlorine reacts and desorbs with Si and a reducing gas having an effect of suppressing an etching reaction due to chlorine, the present invention is directed to the present invention. , Which suppresses the consumption of Si atoms forming the Si substrate and has a low-resistance contact layer TiSi ₂ on the shallow junction layer
Provided is a method for manufacturing a semiconductor device for forming a (titanium silicide) film. That is, according to the present invention, when a TiSi ₂ film is formed on a shallow bonding layer by a plasma CVD method, the consumption of Si by a chlorine-based etching species is suppressed, and the reliability of a low-resistance contact is improved.

[0011]

According to the first aspect of the present invention,
In a method of manufacturing a semiconductor manufacturing apparatus using a CVD method in which a film containing at least a metal halide is plasma-dissociated to form a film on a semiconductor substrate, the temperature of the semiconductor substrate is adjusted by etching between the metal halide and the semiconductor substrate.
A temperature lower than the temperature at which the metallization reaction occurs , a plasma dissociation of a metal halide supplied to the surface of the semiconductor substrate, a deposition process of depositing metal atoms and halogen atoms on the semiconductor substrate, and a substrate temperature of the semiconductor substrate, Metal c
The temperature at which an etching reaction occurs between a logenide and a semiconductor substrate
At the same time , supplying a reducing gas to the surface of the semiconductor substrate, making the reducing gas into a radical state by plasma, and gasifying halogen atoms deposited on the surface of the semiconductor substrate in a deposition process, A removing step of removing halogen atoms from the surface, and a substrate temperature of the semiconductor substrate , a metal atom and a semiconductor constituting the semiconductor substrate.
An alloy forming step of performing processing by setting the temperature to a temperature equal to or higher than the temperature at which atoms are alloyed, and by repeatedly performing the deposition step, the removing step, and the alloy forming step in this order, Forming a film of the alloy having a thickness of

According to a second aspect of the present invention, in the method of manufacturing a semiconductor device according to the first aspect, the metal halide is TiCl ₄ .

According to a third aspect of the present invention, in the method of manufacturing a semiconductor device according to the first or second aspect, the semiconductor substrate temperature in the deposition step is 150 ° C. or less.
There is a feature.

According to a fourth aspect of the present invention, in the method of manufacturing a semiconductor device according to any one of the first to third aspects, the temperature of the semiconductor substrate in the removing step is 150 degrees.
C. or lower .

According to a fifth aspect of the present invention, in the method of manufacturing a semiconductor device according to any one of the first to fourth aspects, a reducing gas that generates hydrogen radicals in plasma in the removing step is used. Thereby, Cl is desorbed from the surface of the semiconductor substrate as HCl.

According to a sixth aspect of the present invention, in the method of manufacturing a semiconductor device according to any one of the first to fifth aspects, the semiconductor substrate is a silicon substrate, and the formed alloy is titanium silicide. There is a feature.

[0017] In TiSi2 film formed by the plasma CVD method, TiCl ₄ used as a raw material gas causes a deposition reaction and an etching reaction at the same time. The etching reaction is
The chlorine contained in the source gas reacts with the underlying Si to produce SiClx
(X = 1-4) is generated and desorbed. The elimination reaction of SiClx is
It depends strongly on the temperature of the Si substrate. The temperature of the Si substrate is about 180 ° C
At this time, it is desorbed by SiCl ₄ , and is desorbed in the form of SiCl ₂ when the temperature of the Si substrate is about 600 ° C., and in the form of SiCl when it is 800 ° C. or more.

Therefore, in order to suppress the consumption of Si and effectively desorb chlorine, the lower the temperature of the Si substrate, the better.
However, the temperature at which silicidation occurs is 500-600 ° C
Therefore, the temperature of the Si substrate in the TiSi ₂ film forming process by the conventional plasma CVD method is set to about 600 ° C. Therefore, during the TiSi ₂ film forming process, the silicidation reaction and the etching reaction occur simultaneously.

Further, by introducing a highly reducing gas and reacting it positively with chlorine-based etching species, the substrate Si
And the reaction with chlorine can be suppressed. However, even if such a gas is introduced during the film forming process of the TiSi ₂ film by the conventional method, etching of the Si substrate by chlorine occurs to a considerable extent.

According to the plasma CVD method of the present invention, a TiSi ₂ film can be formed with good control without breaking a shallow junction on the surface of a Si substrate. In forming a TiSi ₂ film by the plasma CVD method, TiCl ₄ used as a source gas causes a film forming reaction and an etching reaction. The etching reaction is Ti
This occurs because chlorine generated by the decomposition of Cl ₄ reacts with the substrate Si. This etching reaction strongly depends on the temperature of the Si substrate.

Introducing a highly reducing gas and positively reacting with chlorine suppresses the reaction of chlorine with Si atoms on the Si substrate. The plasma CVD method of the present invention uses Si
By controlling the temperature of the substrate and the supply amount of the highly reducing gas, the consumption of chlorine by etching the underlying Si is suppressed.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 are cross-sectional views of a semiconductor device for explaining a process of forming a TiSi ₂ film according to an embodiment of the present invention. Here, the process of this embodiment uses a sample in which an element isolation region is formed in advance by a known method, and a shallow diffusion layer of about 0.1 μm is formed on a Si substrate. Then, a TiSi ₂ film was deposited on the surfaces of the source and drain regions using an ECR-CVD apparatus for the manufacture.

FIG. 1 is a schematic view of a sample prepared in one embodiment of the present invention. Hereinafter, a method of preparing a sample will be briefly described. Field oxide film 2 on the surface of n-type Si (100) substrate 1
Is formed by a conventionally used selective thermal oxidation process. Then, B (boron) atoms are implanted into the exposed surface of the Si substrate 1 by ion implantation. Then, the diffusion layer into which the boron atoms have been implanted is activated by heat treatment to form a shallow p + diffusion layer 3 of about 0.1 μm.

Subsequently, as an interlayer insulating film, SiO 2 is formed by CVD.
_{2 A} film 4 is deposited, and a contact hole 4H is formed on the diffusion layer. Finally, the substrate is washed with a dilute hydrofluoric acid solution to remove a natural oxide film on the surface of the p + diffusion layer 3. After this cleaning, the sample is immediately carried into the ECR-CVD apparatus, and a TiSi ₂ film is formed on the surface of the shallow p + diffusion layer 3 according to the TiSi ₂ film forming process according to the present invention.

The TiSi ₂ film forming process according to the present invention can be roughly divided into three steps as described below. (1) As shown in FIG. 2, when the temperature of the Si substrate 1 is 150 ° C. or less,
The sample was treated in an Ar / H ₂ / TiCl ₄ plasma atmosphere, and the exposed surface of the Si substrate 1 was treated with Ti 9, Cl (chlorine) 7, and Cl ₂ (chlorine).
Cover with 8.

(2) As shown in FIG. 3, since Cl (chlorine) 7 and Cl ₂ (chlorine) 8 adsorbed on the surface of the Si substrate 1 are extracted from the surface of the Si substrate 1, H (hydrogen) having a reducing effect is removed. The surface of the Si substrate 1 is plasma-treated while flowing. As a result, hydrogen radicals 10 decomposed in the plasma and Cl (chlorine) 7, C
l ₂ (chlorine) 8 reacts and desorbs from the surface as HCl 11.

(3) Finally, as shown in FIGS. 4 and 5,
The substrate temperature is set to about 600 ° C. to cause a silicidation reaction. Then, the above-mentioned operations (1) and (2) are repeated until the TiSi ₂ film 12 reaches a target film thickness as shown in FIG. Hereinafter, the TiSi ₂ film formation process will be described in detail while showing the film formation conditions in the TiSi ₂ film formation in one embodiment.

TiClx (x = 1-3) film forming step After setting the temperature of the Si substrate 1 to 100 ° C., as shown in FIG. 2, for example, the Ar / H ₂ / TiCl ₄ flow ratio is set to 30/50 / 0.03. It will be sccm. At this time, it is assumed that the pressure inside the chamber of the ECR-CVD apparatus where the film is formed is about 1 Pa (Pascal). Microwave power is applied at 1000 W, and the surface of the Si substrate 1 is treated in a plasma atmosphere for 5 minutes.

The source gas TiCl is generated by the plasma.
₄ reacts with H (hydrogen) radical, TiClx (x = 1-3)
5, dissociates into TiClx (x = 1-3) 6. TiClx (x = 1-
3) 5, TiClx (x = 1-3) 6 is considered to be a film-forming species component, and dissociates and adsorbs on the exposed surface of the Si substrate 1, and the surface is exposed to Ti
It is covered with atoms or molecules containing 9, Cl7 and Cl8 as components. At this time, since the temperature of the Si substrate 1 is as low as 100 ° C., etching of the Si atoms on the surface of the base Si substrate 1, that is, the surface of the p + diffusion layer 3 by chlorine does not occur.

Cl (chlorine) removal step Next, while maintaining the temperature of the sample at 100 ℃, for example, Ar /
The H ₂ / TiCl ₄ flow rate ratio is changed 30/100/0 sccm. At this time, the pressure inside the chamber of the ECR-CVD apparatus is about 2 Pa, and the power of the microwave is 1000 W. Ar gas is
It is flowing to stably generate plasma.

As a result, as shown in FIG. 3, H radicals 10 are generated by the plasma.
Readily react with the Si substrate 1 was adsorbed on the surface Cl7 and Cl ₂ 8, desorbed from HCl11 next, the Si substrate 1 surface. At this time, the H radical 10 hardly reacts with Ti9.

Thus, H (hydrogen) radical 10 and Cl
7, Cl_TwoReactivity with H8 and the reaction between H radical 10 and Ti9
By utilizing the difference in response, Cl7 and
And Cl _Two8 is selectively removed. Here, the process of one embodiment is described.
In the process example, as shown in FIG.
In minutes, Cl7 and Cl_Two8 is almost all Si substrate 1 table
Detach from surface.

By keeping the temperature of the Si substrate 1 at 100 ° C. at this time, it is possible to suppress the reaction between Si atoms and chlorine atoms at the time of chlorine release, suppress the consumption of Si atoms, and release chlorine. It becomes possible. That, Si substrate 1 by chlorine (CL7 and Cl ₂ 8), suppress the etching of Si in the p + diffusion layer 3 surface.

TiSi ₂ Film Silicidation Step Finally, the flow rate ratio of Ar / H ₂ / TiCl ₄ is set to 0/0/0 sccm, and the Si substrate 1
Temperature to 600 ° C. At this time, the pressure inside the chamber of the ECR-CVD apparatus is, for example, about 1 × 10 ⁻⁶ Pa. By maintaining this temperature for 3 minutes, the Ti
In FIG. 9, as shown in FIG. 5, a silicidation reaction occurs completely with Si of the underlying Si substrate 1 to form a TiSi ₂ film 12.

In order to form the TiSi ₂ film 12 having a desired thickness, the above-described TiClx (x = 1 to 3) film forming step, Cl (chlorine) removing step, and TiSi ₂ film silicidation step are repeated three times. Thus, a desired TiSi2 layer 12 having a thickness of about 10 nm is formed as shown in FIG.

As described above, in the method of forming a TiSi ₂ film according to the present invention, the surface of the Si substrate 1 is covered with Ti 9, Cl 7 and Cl ₂ 8 at a temperature of 150 ° C. or lower where no etching reaction occurs. Next, in order to extract HCl (chlorine) from the Si substrate 1, the surface of the Si substrate 1 is plasma-treated while flowing H (hydrogen) or silane gas having a reducing effect. Hydrogen radicals decomposed in the plasma react with chlorine, and the chlorine becomes HCl
Desorbs from the surface.

Finally, the temperature of the Si substrate 1 is set to about 600 ° C. to cause a silicidation reaction. The above-described series of operations are repeatedly performed until the TiSi ₂ film has a desired thickness. By using the method for forming a TiSi ₂ film of the present invention described above, it is possible to suppress the consumption of Si atoms on the surface of the Si substrate 1 due to chlorine.

As described above, one embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and a design change or the like may be made without departing from the gist of the present invention. The present invention is also included in the present invention.

[0039]

As described above, according to the present invention,
In a method of manufacturing a semiconductor manufacturing apparatus using a CVD method in which a film containing at least a metal halide is plasma-dissociated to form a film on a semiconductor substrate, the temperature of the semiconductor substrate is adjusted by etching between the metal halide and the semiconductor substrate.
A temperature lower than the temperature at which the metallization reaction occurs , a plasma dissociation of a metal halide supplied to the surface of the semiconductor substrate, a deposition process of depositing metal atoms and halogen atoms on the semiconductor substrate, and a substrate temperature of the semiconductor substrate, Metal c
The temperature at which an etching reaction occurs between a logenide and a semiconductor substrate
At the same time , a reducing gas is supplied to the surface of the semiconductor substrate, the reducing gas is turned into a radical state by plasma, and a halogen atom deposited on the surface of the semiconductor substrate in a deposition process is gasified to form a semiconductor substrate. A removing step of removing halogen atoms from the surface, and a substrate temperature of the semiconductor substrate , a metal atom and a semiconductor constituting the semiconductor substrate.
An alloy forming step of performing processing at a temperature higher than the temperature at which atoms are alloyed, and by repeatedly performing the deposition step, the removing step, and the alloy forming step in this order, an arbitrary In order to form a film of the alloy having a thickness of, it is possible to suppress the consumption of the underlying Si due to chlorine, which is a problem in the plasma CVD method using TiCl ₄ gas as a raw material, and as compared with a conventional CVD method or the like. It is easy to control the thickness of the silicide film to be formed. There is an effect that can be formed.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view of the semiconductor device, illustrating a method for manufacturing the semiconductor device according to one embodiment of the present invention;

FIG. 3 is a sectional view of the semiconductor device for explaining a method of manufacturing the semiconductor device according to the embodiment of the present invention;

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

FIG. 5 is a sectional view of the semiconductor device for explaining a method of manufacturing the semiconductor device according to the embodiment of the present invention;

FIG. 6 is a sectional view of the semiconductor device for explaining the method of manufacturing the semiconductor device according to the embodiment of the present invention;

[Explanation of symbols]

REFERENCE SIGNS LIST 1 silicon (Si) substrate 2 field oxide film 3 p + diffusion layer 4 SiO ₂ film 5 TiCl ₂ 6 TiCl ₃ 7 Cl 8 Cl ₂ 9 Ti 10 H radical 11 HCl 12 TiSi ₂

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2000-133617 (JP, A) JP-A-11-204457 (JP, A) JP-A-11-61415 (JP, A) JP-A-7-273046 (JP, A) JP-A-7-41948 (JP, A) JP-A-4-196418 (JP, A) Table 10-508656 (JP, A) Table 10-504604 (JP, A) (JP, A) 58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/285 H01L 21/285 301 C23C 16/08

Claims (6)

(57) [Claims] 1. A method for manufacturing a semiconductor manufacturing apparatus using a CVD method for forming a film on a semiconductor substrate by plasma dissociating a gas containing at least a metal halide, wherein the temperature of the semiconductor substrate is set to a value between the metal halide and the semiconductor. Base
A deposition step of depositing metal atoms and halogen atoms on a semiconductor substrate by plasma dissociating a metal halide supplied to the surface of the semiconductor substrate at a temperature not higher than the temperature at which the plate causes an etching reaction; Temperature controlled with metal halide
A reducing gas is supplied to the surface of the semiconductor substrate at a temperature equal to or lower than a temperature at which an etching reaction occurs with the body substrate, and the reducing gas is turned into a radical state by plasma, and halogen atoms deposited on the surface of the semiconductor substrate in a deposition process. Gasifying the semiconductor substrate to remove halogen atoms from the surface of the semiconductor substrate; and
Set the temperature above the alloying temperature of the constituent semiconductor atoms.
And a alloying process of performing processing, the deposition process, by repeating the removal process and alloying processes in this order, to form a film of the alloy of any thickness on the semiconductor substrate surface A method for manufacturing a semiconductor device, comprising: 2. The method according to claim 1, wherein the metal halide is TiCl ₄ . 3. The semiconductor substrate temperature during the deposition process.
3. The method according to claim 1 , wherein the temperature is 150 [deg.] C. or less . 4. The semiconductor substrate temperature in the removing step.
The method according to claim 1 , wherein the temperature is 150 ° C. or less . 5. 5. The method according to claim 1, wherein in the removing step, Cl is desorbed from the surface of the semiconductor substrate as HCl by using a reducing gas that generates hydrogen radicals in plasma. 5. The method of manufacturing a semiconductor device according to any one of 4. 6. The semiconductor substrate is a silicon substrate,
6. The method according to claim 1, wherein the alloy to be formed is titanium silicide.