JP2727574B2 - Method for manufacturing semiconductor device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a method for manufacturing a semiconductor device, and is particularly suitable for application to the manufacture of a highly integrated semiconductor integrated circuit device.

[Summary of the Invention]

A method of manufacturing a semiconductor device according to the present invention includes a step of forming an insulating film other than a silicon oxide film by a plasma CVD method so as to cover a conductive layer formed on a substrate; and a method of forming a silicon oxide film by a plasma CVD method on the insulating film. Forming a;
Forming a connection hole on the conductive layer by removing a predetermined portion of the silicon oxide film and the insulating film; and selectively growing tungsten by a reduction reaction of a tungsten compound with silane inside the connection hole. To improve the selectivity of the selective growth of tungsten, minimize the design and process changes of the semiconductor device, and especially when a silicon oxide film containing phosphorus is used as the insulating film, the transistor due to penetration of alkali ions. It is intended to prevent deterioration of characteristics and the like.

[Conventional technology]

In recent years, in a highly integrated semiconductor integrated circuit device, tungsten (W) is selectively grown and buried in a contact hole or a through hole formed on a diffusion layer or a metal wiring, and a metal wiring is formed thereon. Techniques for making contact with diffusion layers or metal wiring have begun to be used.

Conventionally, this selective growth of W has been performed by a reduction reaction of tungsten hexafluoride (WF ₆ ) with hydrogen (H ₂ ). However, since the reaction temperature in this case is as high as 400 to 600 ° C., the maximum allowable process temperature is 450 as in the case where W is selectively grown inside a through hole formed on an aluminum (Al) wiring having a low melting point. When the temperature is limited to about ° C, it is difficult to use the selective growth method of W by the H ₂ reduction reaction.

On the other hand, as a method capable of selectively growing W at a lower temperature, a method of selectively growing W by a reduction reaction of WF ₆ with silane (SiH ₄ ) is known. According to this method, W can be selectively grown at a low temperature of about 180 to 400 ° C., so that it can also be used for selectively growing W on an Al wiring.

[Problems to be solved by the invention]

However, according to the study of the present inventor, the interlayer insulating film in which the through hole is formed is particularly formed of phosphorus silicate glass (PS
G) In the case of a film, the nucleus of W grows on the surface of the PSG film during the selective growth of W, and there is a problem that the selectivity of the selective growth of W is poor.

Therefore, an object of the present invention is to improve the selectivity of selective growth of tungsten, to minimize the design and process change of a semiconductor device, and to further reduce the possibility of alkali ion penetration in some cases. An object of the present invention is to provide a method for manufacturing a semiconductor device which can prevent deterioration of transistor characteristics and the like.

[Means for solving the problem]

The present inventor has conducted various experiments in order to solve the above-mentioned problem.
It has been found that in the case of a silicon oxide (SiO _x ) film formed by a mical vapor deposition method, W hardly grows on this SiO _x film.

The present invention has been devised based on the knowledge obtained by the present inventor through independent experiments.

That is, in the method of manufacturing a semiconductor device according to the present invention, an insulating film (5) other than a silicon oxide film is formed by a plasma CVD method so as to cover the conductive layers (3, 4) formed on the substrates (1, 2). And plasma CV on the insulating film (5)
A step of forming a silicon oxide film (6) by a method D; removing predetermined portions of the silicon oxide film (6) and the insulating film (5) to form connection holes (H ₁ , H ₂ ) is formed, and tungsten (7, ₂ ) is formed in the connection holes (H ₁ , H ₂ ) by a reduction reaction of a tungsten compound with silane.
And 8) selectively growing.

If the thickness of the silicon oxide film (6) is less than about 20 nm, pinholes in the film may increase and the selectivity of selective growth may decrease. Preferably, the thickness is about 20 nm or more.

[Action]

According to the above means, tungsten hardly grows on the silicon oxide film (6) formed by the plasma CVD method, and tungsten grows only on the surface to be selectively grown. Thereby, the selectivity of the selective growth of tungsten can be improved. Further, a silicon oxide film formed by a plasma CVD method for selective growth of tungsten may be as thin as several tens of nanometers, so that a change in the design and process of a semiconductor device can be minimized.
Furthermore, since a silicon oxide film containing phosphorus typified by a PSG film has a high barrier property against alkali ions, when a silicon oxide film containing phosphorus is used as an insulating film, deterioration of transistor characteristics due to penetration of alkali ions is reduced. Etc. can be prevented.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1A to 1C show a method of manufacturing a semiconductor integrated circuit device according to an embodiment of the present invention in the order of steps.

In this embodiment, as shown in FIG. 1A, for example, SiO ₂ formed on a semiconductor substrate 1 such as a silicon (Si) substrate on which a diffusion layer or the like (not shown) is formed in advance. After the first-layer wirings 3 and 4 made of, for example, Al are formed on the insulating film 2 such as a film, a PSG film 5 containing, for example, 4.5% by weight of phosphorus (P) is formed as an interlayer insulating film on the entire surface by, for example, a CVD method. Form. The thickness of the PSG film 5 is, for example, 600 nm.
It is about. Next, an SiO _x film (hereinafter, referred to as a p-SiO _x film) 6 having a thickness of, for example, about 50 nm is formed on the entire surface of the PSG film 5 by a plasma CVD method at a low temperature. As the reaction gas at the time of this plasma CVD, (SiH ₄ + N ₂ O), TEOS (tetotaethoxysilane), (TEOS + O ₂ ), or the like can be used.

Next, predetermined portions of the p-SiO _x film 6 and the interlayer insulating film 5 are sequentially anisotropically etched in a direction perpendicular to the substrate surface by, for example, reactive ion etching (RIE), as shown in FIG. 1B. Then, through holes H ₁ and H ₂ are formed on the wirings 3 and 4, respectively.

Next, W is selectively grown by, for example, a reduction reaction of WF _{6 with} SiH ₄ represented by the following formula. This growth is performed at a temperature in the range of 180-400 ° C, for example, 280 ° C.

WF ₆ (g) + SiH ₄ (g) → W (s) + SiF ₄ (g) + 2H ₂ (g) As a result, as shown in FIG.
W grows selectively in H ₁ and H ₂ , and these through holes H ₁ and H ₂
Internal H ₂ are filled by respective W7,8. On this occasion,
W hardly grows on the p-SiO _x film 6.

Thereafter, a second-layer wiring made of, for example, Al (not shown)
Through a process such as formation of a semiconductor integrated circuit device, a target semiconductor integrated circuit device is completed.

As described above, according to this embodiment, W is selectively grown by the reduction reaction of WF ₆ with SiH ₄ while the surface of the non-growth region is covered with the p-SiO _x film 6. No W growth occurs on the surface of the growth area, and through holes H ₁ and H ₂
W grows selectively only inside. Thereby, the selectivity of the selective growth of W can be improved. Further, since the selective growth of W can be performed at a low temperature, as described above,
W can be selectively grown on the Al wiring.

Furthermore, since the PSG film 5 having a high barrier property against alkali ions such as Na ⁺ is used as an interlayer insulating film,
Deterioration of transistor characteristics and the like due to intrusion of alkali ions can be prevented, whereby reliability of the semiconductor integrated circuit device can be improved.

The method for selectively growing W according to the present embodiment can be applied to the manufacture of various semiconductor integrated circuit devices such as a MOS LSI, a bipolar LSI, and a bipolar CMOS LSI.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications based on the technical idea of the present invention are possible.

For example, in the above-described embodiment, the first-layer wiring 3,
Although the case where the through holes H ₁ and H ₂ formed on the semiconductor substrate 1 are filled with W has been described, the present invention relates to a case where the contact hole formed on the diffusion layer formed in the semiconductor substrate 1 is filled with W, for example. It is also possible to apply to. Also,
In the above embodiment, the PSG film 5 is used as the interlayer insulating film. However, an insulating film different from the PSG film 5 can be used as the interlayer insulating film.

〔The invention's effect〕

As described above, according to the present invention, it is possible to improve the selectivity of the selective growth of tungsten, and it is possible to minimize changes in the design and process of a semiconductor device,
In the case where a silicon oxide film containing phosphorus is used as the insulating film, deterioration of transistor characteristics and the like due to entry of alkali ions can be prevented.

[Brief description of the drawings]

1A to 1C are sectional views showing a method of manufacturing a semiconductor integrated circuit device according to an embodiment of the present invention in the order of steps. Description of the key symbols in drawings 1: semiconductor substrate, 3,4: first-layer wiring, 5: PSG film, 6: p-SiO _x film, 7, 8: W, H _1, H _2: through-hole.

Claims (1)

(57) [Claims] A step of forming an insulating film other than a silicon oxide film by a plasma CVD method so as to cover a conductive layer formed on a substrate; and a step of forming a silicon oxide film on the insulating film by a plasma CVD method. Forming a connection hole on the conductive layer by removing a predetermined portion of the silicon oxide film and the insulating film; and selectively growing tungsten in the connection hole by a reduction reaction of a tungsten compound with silane. A method of manufacturing a semiconductor device, comprising: