JP3070577B2 - 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, and more particularly, to a method for manufacturing a semiconductor device having a contact hole or a via hole.

[0002]

2. Description of the Related Art In recent years, the aspect ratio (depth / opening diameter) of a contact hole has been increasing along with the high integration of LSI. A semiconductor device in which a tungsten film is buried in a contact hole of a semiconductor substrate has been proposed to improve the step coverage of the contact hole.

In a conventional semiconductor device, a Ti film and a TiN film are continuously formed in a contact hole formed in a semiconductor substrate by a sputtering method, and subsequently, a Si film is formed at about 5 Torr.
H ₄ (monosilane), WF ₆ (tungsten hexafluoride)
After tungsten nucleation by H ₂ , WF
₆ embeds a tungsten film.

FIG. 3A shows a conventional contact hole buried with a tungsten film, a semiconductor substrate having a conductive layer 1 and an insulating film 2, a contact hole 2A formed in the insulating film 2, and a contact hole. 2A and a TiN film formed on the Ti film
A Ti / TiN film 7 formed of a film;
A first tungsten film 8 formed on the N film 7;
And a second tungsten film (not shown) that covers the tungsten film 8 to form a tungsten plug. In the tact hole 2A, when the aspect ratio increases, the step coverage of the Ti / TiN film 7 formed by the sputtering method is limited. As a solution to this, after forming a Ti film by ionization sputtering,
A method for manufacturing a semiconductor device in which a TiN film is formed by a chemical vapor deposition (CVD) method has been proposed.

[0005]

[SUMMARY OF THE INVENTION However, according to the conventional method of manufacturing a semiconductor device, because it may cause outgassing in the process of forming a TiN film by CVD, SiH _4, WF ₆ gas upon the nucleation of tungsten Did not reach the bottom of the contact hole, resulting in FIG.
As shown in (b), a first step is performed on the Ti / TiN film 7 in a later step.
When the tungsten film 8 is formed and the second tungsten film 9 is further formed, a void B is generated in the tungsten plug 9 'embedded in the contact hole 2A, and the yield and the long-term reliability of the semiconductor device are reduced. is there. Accordingly, an object of the present invention is to provide a method of manufacturing a semiconductor device in which the filling of tungsten is not hindered by generation of outgas.

[0006]

In order to achieve the above object, the present invention provides a method of manufacturing a semiconductor device having an interlayer connection hole such as a contact hole or a via hole in an interlayer insulation film. A barrier layer as a conductor film is formed on the film, and 30 to 50 Torr
Forming a first tungsten nucleation layer on the barrier layer by SiH ₄ and WF ₆ under a pressure of 5 Torr, and forming a second tungsten nucleation layer on the first tungsten nucleation layer by SiH ₄ and WF ₆ under a pressure of 5 Torr or less. Forming a core layer, WF
_A method for manufacturing a semiconductor device, wherein a third tungsten nucleation layer is formed on the second tungsten nucleation layer by ₆ and H ₂ is provided.

In the method of manufacturing a semiconductor device described above,
The barrier layer is formed by a T
Ti / Ti film with a TiN film formed by chemical vapor deposition on the i film
It is preferably a TiN film.

[0008] In order to achieve the above object, the present invention provides:
In a method of manufacturing a semiconductor device in which a tungsten film is filled in an interlayer connection hole such as a contact hole or a via hole formed in an interlayer insulating film, a TiN film is formed in the interlayer connection hole by an ionization sputtering method. Under the pressure of the value to suppress the outgassing
forming a first tungsten nucleation layer on the iN film with SiH ₄ and WF ₆ , and forming a second tungsten nucleation layer on the first tungsten nucleation layer with SiH ₄ and WF ₆ under a pressure reduced by the predetermined value; A method for manufacturing a semiconductor device, comprising forming a layer and forming a third tungsten nucleation layer on the second tungsten nucleation layer with WF ₆ and H ₂ .

In the method of manufacturing a semiconductor device described above,
In the step of forming the first tungsten nucleation layer, it is preferable to set a pressure of 30 to 50 Torr as a pressure that suppresses outgassing, and the step of forming a predetermined second tungsten nucleation layer is performed by reducing the pressure by a predetermined value. It is preferable to set a pressure of 5 Torr or less as the resulting pressure.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a semiconductor device according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a cross section of a semiconductor device formed by a method of manufacturing a semiconductor device according to an embodiment of the present invention. FIG. 1A shows a semiconductor substrate having a conductive layer 1 and an insulating film 2 and a contact hole 2 opened in the insulating film 2.
A, a Ti film formed by ionization sputtering, and a TiN film formed by CVD after the formation of the Ti film to form a Ti / TiN film 3 as a barrier metal, and a nucleus on the Ti / TiN film 3 A state where a first tungsten film 4 as a formation film is formed is shown.

FIG. 1B shows a state in which a second tungsten film 5 as a nucleation film is formed on the first tungsten film 4 formed in the contact hole 2A.

FIG. 1C shows a state in which a third tungsten film 6 is coated on the second tungsten film 5 and a tungsten plug 6 'is buried in the contact hole 2A.

Hereinafter, a method for manufacturing a semiconductor device according to the present invention will be described in detail with reference to the drawings.

FIG. 2 shows a flow chart of a method of manufacturing a semiconductor device according to the present invention. First, a pattern of a contact hole is formed on an insulating film of a semiconductor substrate having a conductive layer and an insulating film by a photolithography technique. A contact hole is opened by etching the insulating film having the above (Step 1).

Next, a Ti film is formed in the contact hole by ionization sputtering (step 2).
By forming a TiN film by the D method, a Ti / TiN film as a barrier metal is formed (Step 3).

After the formation of the barrier metal, 30 to 50 Torr
the SiH _4, WF ₆ gas under a pressure of r 100 to, as a nucleating film over the Ti / TiN film of the contact hole
A 200 ° first tungsten film is formed. This first
Even if outgassing occurs from the Ti / TiN film during the formation of the tungsten film, a uniform nucleation film is formed because SiH ₄ and WF ₆ spread to the bottom of the contact hole under high pressure (step 4).

Next, at a pressure of 5 Torr or less, the Si
A second tungsten film of 300 to 400 ° is formed with H ₄ and WF ₆ gas (step 5).

Next, tungsten is buried in the contact holes by forming a second tungsten film with WF ₆ and H ₂ gases (step 6).

According to the method of manufacturing a semiconductor device described above,
By forming a first tungsten film serving as the nucleation film by SiH _4, WF ₆ under high pressure 30~50Torr, SiH _4, WF to the bottom of the contact hole
_{Since 6} gases are distributed, Ti formed by the CVD method
The outgas generated from the N film does not hinder the tungsten film formation process. This makes it possible to form a uniform tungsten film without causing defects such as voids in contact holes having a large aspect ratio.

As another method of forming a tungsten film, a semiconductor substrate having a contact hole in which a Ti / TiN film is formed is formed by etching a SiH film under a high pressure of 30 to 50 Torr.
_{4. A} first tungsten film of several tens of degrees is formed by WF ₆ gas. This first tungsten film is Ti / Ti
The thickness may be such that outgas generated from the N film can be suppressed. The semiconductor substrate having the first tungsten film formed as described above is subjected to SiH ₄ , WF at 5 Torr or less.
_A 500 ° second tungsten film is formed with ₆ gases. According to this method, the coverage of the second tungsten film is better than that of the first tungsten film, so that the tungsten burying property can be further improved.

[0022]

As described above, according to the method of manufacturing a semiconductor device of the present invention, a barrier layer as a conductor film is formed on an insulating film of a semiconductor substrate having an interlayer connection hole.
First with SiH ₄ and WF ₆ at a pressure of 50 Torr
The first nucleation layer is formed on the barrier layer by performing nucleation of SiH ₄ and WF ₆ under a pressure of 5 Torr or less.
Forming a second nucleation layer on the first nucleation layer by performing the second nucleation by WF ₆ and H ₂ , and forming a third nucleation layer on the second nucleation layer by performing the third nucleation by WF ₆ and H ₂ Since the nucleation layer is formed, the burying of tungsten due to the generation of outgas can be prevented from being hindered.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view illustrating a semiconductor substrate according to an embodiment of the present invention. (B) is a sectional view showing the semiconductor substrate according to the embodiment of the present invention. (C) is a sectional view showing a semiconductor substrate according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a method for manufacturing a semiconductor device according to the present invention.

FIG. 3A is a cross-sectional view showing a conventional semiconductor substrate.
(B) is a sectional view showing a conventional semiconductor substrate.

[Explanation of symbols]

 1, conductive layer 2, insulating film 2A, contact hole 3, Ti / TiN film 4, first tungsten film 5, second tungsten film 6, third tungsten film 6 ', tungsten plug 7, Ti / TiN film 8, first tungsten film 9, second tungsten film 9 ', tungsten plug B, void

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-272049 (JP, A) JP-A-5-144951 (JP, A) JP-A-10-125625 (JP, A) JP-A-1- 27243 (JP, A) JP-A-7-22414 (JP, A) JP-A-7-245300 (JP, A) JP-A 10-189493 (JP, A) JP-A 8-115977 (JP, A) JP-A-8-241895 (JP, A) JP-A-6-275624 (JP, A) JP-A-6-29236 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/285 H01L 21/28 301 H01L 21/3205 H01L 21/768

Claims (5)

(57) [Claims] 1. A method of manufacturing a semiconductor device having an interlayer connection hole such as a contact hole or a via hole in an interlayer insulation film, comprising: forming a barrier layer as a conductor film on the interlayer insulation film having the interlayer connection hole; a first tungsten nucleation layer is formed on the barrier layer at a pressure of 30~50Torr by SiH ₄ and WF _6, first in the first tungsten nucleation layer by SiH ₄ and WF ₆ under a pressure of less than 5Torr 2. A method for manufacturing a semiconductor device, comprising: forming a second tungsten nucleation layer; and forming a third tungsten nucleation layer on the second tungsten nucleation layer using WF ₆ and H ₂ . 2. The method according to claim 1, wherein the barrier layer is formed of TiN by chemical vapor deposition on a Ti film formed by ionization sputtering.
2. The method for manufacturing a semiconductor device according to claim 1, wherein said method is a Ti / TiN film having a film formed thereon. 3. A method of manufacturing a semiconductor device in which an interlayer connection hole such as a contact hole or a via hole formed in an interlayer insulation film is filled with a tungsten film, wherein a TiN film is formed in the interlayer connection hole by ionization sputtering. Forming a first tungsten nucleation layer on the TiN film with SiH ₄ and WF ₆ under a pressure that suppresses outgas generated during the formation of TiN; and forming the first tungsten nucleation layer under a pressure smaller than the predetermined value. A semiconductor, comprising: forming a second tungsten nucleation layer on the nucleation layer with SiH ₄ and WF ₆ ; and forming a third tungsten nucleation layer on the second tungsten nucleation layer with WF ₆ and H ₂ . Device manufacturing method. 4. The step of forming the first tungsten nucleation layer, wherein the pressure of the value for suppressing the outgas is 3
4. The method according to claim 3, wherein a pressure of 0 to 50 Torr is set. 5. The step of forming the second tungsten nucleation layer includes the step of reducing the pressure by 5To
4. The method for manufacturing a semiconductor device according to claim 3, wherein the pressure is set equal to or lower than rr.