JPH09134918A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means for improving the adhesion of a WSi layer to another layer, such as an SiO layer, which is formed on the WSi layer. SOLUTION: This method forms another layer, such as an SiO layer 4, on a WSi layer 2 formed on a polycrystalline silicon layer 1 by a CVD method or the like. In this case, fluorines (F) 3 taken into a process of forming a WSi layer 21 by applying a heat treatment to the layer 2 or a process of forming a low-resistance WSi layer 21 by ion-implanting impurities in the layer 2 are made to separate out on the surface of the layer 21 and after fluorines (F) 3 seprated out on the surface of the layer 21 are removed by a wet treatment, the layer 4, which is the other layer, is formed. Subsequently to this process, in the case where the layer 4, which is the other layer, is formed on the layer 21 , a heat treatment in a range of 600 to 800 deg.C is applied to the layer 21 in a vacuum of a pressure of 0Torr or lower, for example, by a lamping process or the like to stabilize the crystal of the layer 21 .

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to S on a WSi layer.
iO layer (In this specification, the SiO layer is SiO _TwoEtc.
Other layers of silicon oxide layer)
Related to a method of manufacturing a semiconductor device using a process of forming
It is.

[0002]

2. Description of the Related Art In recent years, with the progress of higher density and higher integration of semiconductor devices, it has been strongly demanded to reduce the electric resistance of wirings. As a material capable of reducing the electric resistance of wirings, tungsten silicide ( WSi) has attracted attention, and various semiconductor devices using the WSi layer as a wiring layer and manufacturing methods thereof are now being intensively studied.

[0003]

In the conventional manufacturing process of a semiconductor device using a WSi layer as a wiring layer, WS is used.
When the i layer is formed by the CVD method, if a fluoride such as WF ₆ is used as a source gas, fluorine (F) may be incorporated in the formed WSi layer, and the formed WSi layer may be fluoride. In the step of reducing the resistance by ion-implanting (II) boron (B) using a boron bromide (BF ₂ ) gas,
F was sometimes incorporated into the WSi layer.

In such a case, F contained in the WSi layer at the temperature at which another layer such as the SiO layer is formed on the WSi layer is not included in the WSi layer and other upper layers such as SiO. It was sometimes deposited at the interface of layers.

As described above, when another layer such as SiO is formed on the WSi layer, F contained in the WSi layer is formed on the surface of the WSi layer at the temperature for forming the other layer. The WSi layer and the S may be separated from each other by the deposited F, the deposited F, or the thermal stress caused by the instability of the crystal.
Adhesion to other layers such as iO may be deteriorated, which may adversely affect the characteristics of the semiconductor device and the manufacturing process. An object of the present invention is to provide a means for improving the adhesion between the WSi layer and another layer such as SiO formed thereon.

[0006]

In a method of manufacturing a semiconductor device according to the present invention, a WSi formed by a CVD method or the like is used.
In the step of forming another layer such as a SiO layer on the layer,
By performing heat treatment on the WSi layer, fluorine (F) taken in in the step of forming the WSi layer or in the step of ion-implanting impurities into the WSi layer is deposited on the surface of the WSi layer and deposited on the surface of the WSi layer. A step of forming another layer after removing F by a wet treatment was adopted.

Further, in this case, in the step of forming another layer on the WSi layer, for example, in a vacuum of 1.0 Torr or less, 600 to 800 by a ramping process or the like.
A heat treatment in the range of ° C can be applied.

In order to improve the adhesion between the WSi layer and another layer such as a SiO layer on the WSi layer, (1) the WSi layer and another layer such as a SiO layer on the WSi layer. Removing F near the interface that inhibits the binding between. (2) When heat is applied, the WSi layer and Si on it are
Tension (TENSIL) generated between other layers such as O layer
E) Focused on relieving stress.

FIG. 1 is a process explanatory view of a method of depositing fluorine contained in the WSi layer on the surface and performing wet treatment to remove it. This is because the fluorine (F) deposited on the surface of the WSi layer in the step of forming another layer such as the SiO layer is previously added to the W layer.
Before forming another layer such as a SiO layer on the Si layer, WSi
This is a step for depositing on the layer and removing this F by a wet treatment to improve the adhesion between the WSi layer and another layer such as the SiO layer thereon.

First Step (See FIG. 1A) A WSi layer is formed on a substrate. Second step (see FIG. 1B) The WSi layer formed in the first step is contained in the WSi layer by heat treatment (annealing) at a temperature higher than the temperature at which another layer is formed thereon. Deposited F on the surface of the WSi layer. Third Step (see FIG. 1C) F deposited on the surface of the WSi layer in the second step is removed by wet treatment with fluorine / persulfuric acid + nitric acid or the like. Fourth step (see FIG. 1D) Another layer such as SiO is formed on the surface of the WSi layer from which F deposited on the surface in the third step is removed.

By doing so, the adhesion between the WSi layer and another layer such as SiO formed thereon can be improved.

FIG. 2 is an explanatory view of steps of a method for stabilizing the crystal structure. First step (see FIG. 2A) A WSi layer is formed on a substrate, and fluorine contained in the WSi layer is deposited on the surface by the step described in FIG. 1 and removed by wet treatment. Second step (see FIG. 2B) The WSi layer formed in the first step is load-in maintained at a temperature of around 700 ° C. Third step (see FIG. 2C) Another layer such as SiO is formed on the WSi layer heat-treated in the second step. In this case, since the heat treatment in the second step is a step for stabilizing the crystal structure, at least part of the step of forming another layer such as SiO on the WSi layer,
Preferably, it may be added near the final step.

By doing so, the crystal structure of the WSi layer changes to a stable Tetragonal structure, stress during film formation is relieved, and the Si formed on the WSi layer and above it.
Adhesion with other layers such as O can be improved.

In summary of the method for manufacturing a semiconductor device of the present invention, after forming a WSi layer, heat treatment (annealing) and wet treatment are applied to form another layer such as SiO on the WSi layer to form a WSi layer. When F on the surface of the layer is removed (Fig. 1
In the step of forming another layer thereon, it is possible to reduce the precipitation of F, and in this case, heat treatment is performed in the step of forming another layer such as SiO on the WSi layer. When added (step described with reference to FIG. 1), the adhesion between the WSi layer and another layer such as SiO formed thereon can be improved, and deterioration of the characteristics of the wiring layer and thus the semiconductor device can be prevented. You can

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 is a process explanatory diagram of a method for manufacturing a semiconductor device according to a first embodiment. In this figure, 1 is a polycrystalline silicon layer, 2 is a WSi layer, 2 ₁ is a low resistance WSi layer, 3 is F, and 4 is a SiO layer.

First Step (see FIG. 3A) A WSi layer 2 is formed on a polycrystalline silicon (Poly-Si) layer 1.

Second step (see FIG. 3B) Boron (B) is ion-implanted into the WSi layer 1 formed in the first step by using a boron fluoride (BF ₂ ) gas to lower the resistance of the WSi layer 2. The WSi layer 2 ₁ is used.

Third Step (see FIG. 3C) The low resistance WSi layer 2 ₁ into which B is ion-implanted in the second step is heat-treated at a temperature of about 800 ° C. By this heat treatment, the fluorine (F) 3 incorporated in the low resistance WSi layer 2 ₁ is deposited on the surface thereof.

Fourth step (see FIG. 3D) Low resistance WSi having fluorine (F) 3 deposited on the surface in the third step
The layer 2 ₁ is wet-treated with (persulfuric acid + nitric acid or the like) to remove F3 deposited on the surface of the low resistance WSi layer 2 ₁ .

Fifth Step (see FIG. 3E) On the low resistance WSi layer 2 ₁ from which F on the surface has been removed in the fourth step, another layer SiO 2 is formed.

The F removing step in the fourth step is not limited to the wet process using chemicals, and cleaning means such as gas or steam can be used.

FIG. 4 is an explanatory view of a thermal sequence of the method of manufacturing the semiconductor device according to the first embodiment. The method of manufacturing the semiconductor device according to the present embodiment will be described with reference to this thermal sequence explanatory diagram.

(See FIG. 4 (Region A)) W formed on a polycrystalline silicon (Poly-Si) layer
After the F deposited on the surface of the Si layer is wet-treated and removed, it is loaded into a chamber under the conditions of about 700 ° C. and an atmospheric pressure of 0.9 Torr.

(See FIG. 4 (Region B)) 18 at about 700 ° C. and atmospheric pressure of 0.9 Torr.
Hold for a minute.

(See FIG. 4 (Region C)) At an atmospheric pressure of 0.9 Torr, 7.69 [° C. /
Min] for 13 minutes, and the temperature is gradually raised to 800 ° C. by ramping up. This temperature is 600 ℃ or more 800
When the temperature is not higher than C, F in the WSi layer can be deposited on the surface of the WSi layer, and the deterioration of the crystal structure of the WSi layer or the like can be prevented.

(See FIG. 4 (Region D)) An SiO layer is formed by the CVD method.

(See FIG. 4 (region E)) The WSi layer on which the SiO layer is formed is ramped down to 1
Gradually lower the temperature to 700 ° C. over 0 minutes.

Sixth step (see FIG. 4 (region F)) The WSi layer on which the SiO layer is formed is taken out of the chamber.

By this heat treatment, as described above, WS
The crystal structure of the i layer is changed to a stable Tetragonal structure, and the stress at the time of forming the SiO layer is relieved,
Coupled with the absence of F at the interface between the WSi layer and the SiO layer, the adhesion between the WSi layer and the SiO layer, which is another layer, can be improved. Note that the temperature change can be relieved by ramping up and down using a ramping process, so that damage to the crystal structure due to thermal stress can be prevented. In addition, this heat treatment When it is performed in a vacuum of Torr or lower, damage to the crystal structure can be prevented.

[0030]

As described above, according to the present invention,
Since the step of forming the WSi layer or the step of removing F taken in by the step of introducing impurities into the WSi layer is provided, it is possible to reduce the occurrence of white turbidity due to F when forming another layer formed thereon. In addition, heat treatment is applied in the step of forming another layer on the WSi layer to stabilize the crystal structure, so that the thermal stress between the WSi layer and another layer formed on the WSi layer is relaxed. Therefore, the occurrence of peeling of other layers can be suppressed, which greatly contributes to reduction of failures such as patterning failure and interlayer insulation failure in the semiconductor manufacturing process.

[Brief description of the drawings]

FIG. 1 is a process explanatory view of a method of depositing fluorine contained in a WSi layer on a surface and performing wet treatment to remove it.

FIG. 2 is a process explanatory diagram of a method for stabilizing a crystal structure.

FIG. 3 is a process explanatory view of the manufacturing method of the semiconductor device of the first embodiment.

FIG. 4 is a thermal sequence explanatory diagram of the method for manufacturing the semiconductor device of the first embodiment.

[Explanation of symbols]

1 Polycrystalline Silicon Layer 2 WSi Layer 2 ₁ Low Resistance WSi Layer 3 F 4 SiO Layer

Claims (4)

[Claims] 1. A heat treatment of fluorine (F) taken into a WSi layer in the step of forming another layer on the WSi layer or the step of ion-implanting impurities into the WSi layer. By adding WSi
A method of manufacturing a semiconductor device, comprising: a step of depositing F on a surface of a layer, removing F deposited on a surface of a WSi layer by a wet process, and then forming another layer. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the heat treatment applied in the step of forming another layer on the WSi layer is performed in the range of 600 to 800 ° C. 3. The method of manufacturing a semiconductor device according to claim 2, wherein the heat treatment applied in the step of forming another layer on the WSi layer is performed by a ramping process. 4. The manufacturing of a semiconductor device according to claim 2, wherein the heat treatment applied in the step of forming another layer on the WSi layer is performed in a vacuum of 1.0 Torr or less. Method.