JP3200979B2 - Method of forming plug-in vertical wiring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a plug-in vertical wiring for electrically connecting wirings of an ultra-high-integration semiconductor device, and more particularly, to a method of forming a three-dimensional conductive layer for higher density. It is concerned with the formation of wirings that are arranged in a random fashion.

[0002]

2. Description of the Related Art The ultra-high integration of semiconductor devices is on the rise, and the demand for technologies for realizing it is increasing. This can be clearly understood from the fact that a UV stepper is demanding an exposure technology (for example, a KrF excimer laser or the like) having a shorter wavelength than UV, from g-line to i-line. These exposure techniques determine the so-called minimum dimension of the design rule. It is no exaggeration to say that the development of this exposure technology has promoted the miniaturization of the semiconductor devices described above.

On the other hand, there is a limit in miniaturization only by this exposure technique. That is, the device dimensions, and thus the structure, and further the cell area are limited by the minimum dimensions of the exposure technique. Therefore, in order to achieve higher density using the current exposure technology, it is necessary to consider three-dimensional devices. For example, trench cells that have attracted attention in DRAMs and FIN structures that are attracting attention now are the most prominent.

By the way, this idea has begun to be applied to multilayer wiring. For example, Proceedings of the 38th Federation of Applied Physics-related Lectures, 1991, pp. 691, 30
Plug-in vertical wiring process shown in p-W-8. This technology is an active layer stacking device that aims at high density without miniaturization, and arranges conductive layers to form electrodes three-dimensionally, which has been an obstacle to high density of conventional structure, This is to solve the disadvantage that the area of the wiring is increased, and as shown in FIG. 10, is connected to an interlayer insulating film 2, an upper wiring 3, and an interlayer insulating film 4 which are sequentially formed on a diffusion layer 1 as a lower wiring layer. This is a technique for making a connection by opening a hole 6 and embedding a plug 5 in a connection hole 6.

[0005]

However, when using this technique, the problem is what technique is used to form the plug 5. That is, considering the simplicity of the process, a selective WCVD technique or the like may be used. However, when this technique is used, as shown in FIG. 11, the plugs 5 begin to grow separately only from the conductors, so that voids 7 are formed. There's a problem.

On the other hand, the use of the blanket-W requires an adhesion layer. This adhesion layer is a sputtered film, and FIG.
As shown in (1), if the coverage of the adhesion layer 8 is poor, there is also a problem that voids 7 are formed in the blanket-W film 9. In particular, since the aspect ratio of the connection hole is large in the plug-in vertical wiring, it is easily predicted that the generation of such voids 7 is particularly problematic.

The present invention has been made in view of such a problem, and has as its object to obtain a method for forming a plug-in vertical wiring in which a plug conductor can be embedded in a connection hole without generating a void. Things.

[0008]

According to the first aspect of the present invention,
On the lower wiring including the diffusion layer, a small amount of
At least one upper layer wiring is formed and
Structure with the uppermost interlayer insulating film formed on the upper wiring
On the other hand, a connection hole for exposing the lower wiring is opened,
How to form plug-in vertical wiring to form plugs in connection holes
Prior to the step of opening said connection hole,
Forming a first adhesion layer on the surface of the interlayer insulating film
After opening the connection hole, a second adhesion layer is formed on the entire surface.
A blanket tungsten film is formed and then the
Aluminum in the connection hole with the blanket tungsten film
Filling with a high-temperature sputtering method using
This is the solution.

[0009]

According to the present invention, a blanket tungsten film having good step coverage is formed on the entire surface in advance, so that it serves as an adhesion layer, and also as a heat-resistant barrier layer for the lower wiring and the plug material.
, The adhesion layer made of the blanket tungsten film is sufficiently maintained. Furthermore, since the blanket tungsten film is formed with good coverage, no void is generated even if the metal plug is formed by high-temperature sputtering Al. In addition, blanket tungsten film (second adhesion)
First adhesion that can ensure adhesion with the insulating film under the layer)
Layer, blanket tungsten film adhesion
Becomes better.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the method for forming a plug-in vertical wiring according to the present invention will be described below with reference to the embodiments shown in the drawings.

(Embodiment 1) FIGS. 1 to 8 are cross-sectional views of essential parts showing a step of forming a plug-in vertical wiring of this embodiment.

First, as shown in FIG.
At a predetermined position of 0, an impurity diffusion layer 10a is formed as a lower wiring layer formed of, for example, an n ⁺ region into which arsenic (As) is ion-implanted.

Next, ions of argon (Ar ⁺ ), which is an inert substance, are converted into Ie16 /
As shown in FIG. 2, ion implantation is performed at a dose of 80 cm ² from the surface of the impurity diffusion layer 10a made of single crystal.
Amorphous regions up to the depth of the amorphous silicon layer 1
Form one.

Next, a dry oxidation treatment (heat treatment at an O ₂ flow rate of 10 l / min. For 10 minutes) at 850 ° C. is performed to a depth of, for example, 50 ° from the surface of the amorphous silicon layer 11 as shown in FIG. After a silicon oxide film 12 is formed, a titanium film 13 is formed on the silicon oxide film 12 by a sputtering method as shown in FIG.

Thereafter, rapid thermal annealing (RT
A) is performed in an argon (Ar) atmosphere at 650 ° C. for 30 seconds to form a titanium silicide film 14. Then, the unreacted titanium film 13 is selectively wet-etched by immersing the wafer in ammonia peroxide for 10 minutes (FIG. 4). Furthermore, 90 minutes in a nitrogen (N ₂ ) atmosphere.
Annealing is performed at 0 ° C. for 30 seconds to form a titanium silicide film 14 having low resistance and stability.

[0016] Next, as shown in FIG. 5, on a substrate, a first interlayer insulating film in the atmospheric pressure CVD (SiO ₂₎ 15, for example 3
Then, a P ⁺ -polysilicon film 16 as an upper layer wiring is deposited at a thickness of, for example, 20 nm by a low pressure CVD method.
0 nm in film thickness, and furthermore, a normal pressure C
The second interlayer insulating film (SiO ₂ ) 17 is, for example, 30
Deposit to a thickness of 0 nm. Thereafter, as shown in FIG. 2, titanium (T) is formed on the second interlayer insulating film (SiO ₂ ) 17.
i) / titanium oxynitride (TiON) = 30n
An adhesion layer 18 of m / 70 nm is formed by a sputtering method.

Next, as shown in FIG. 6, a wiring connection hole 19 is formed on the titanium silicide film 14 by dry etching. In the present embodiment, the connection hole radius is set to 0.
The thickness was 5 μm.

Next, the wafer is put into a blanket-WCVD apparatus, and the following two-stage CVD is performed to
As shown in FIG. 7, a blanket tungsten film 21 as an adhesion layer having a thickness of 100 nm is deposited on the entire surface.

(First-stage CVD) O Gas and its flow rate WF ₆ 25 _SCCM SiH ₄ 10 _SCCM O Pressure 1.07 x 10 ⁴ Pa (80 Torr) O Temperature 475 ° C (Second-stage CVD) ○ Gas and its flow rate WF ₆ 60 _SCCM H ₂ 360 _SCCM ○ Pressure 1.07 × 10 ⁴ Pa (80 Torr) ○ Temperature 475 ° C.
Is deposited to form a plug 20 (FIG. 8). The conditions for the high-temperature sputtering are as follows.

(High temperature sputtering conditions) Ar flow rate: 40 _SCCM Pressure: 0.04 Pa DC power: 10 kW Temperature: 500 ° C. In this embodiment, an adhesive layer having a uniform film thickness is formed on the inner surface of the wiring connection hole 19. Can be formed by the blanket tungsten film 21, so that metal plugs (Al) can be satisfactorily buried, voids can be prevented, and the reliability of wiring can be improved. In particular, in this embodiment, a so-called SITOX is formed on the surface of the impurity diffusion layer 10a as a lower wiring.
-Since the titanium silicide film 14 is formed, agglomeration of silicide due to high temperature does not occur, and low-resistance contact characteristics can be obtained. Also, blanket tongue
Under the stainless film 21, adhesion to the second interlayer insulating film 17 is improved.
Good adhesion layer 18 is formed and blanket tongues
The adhesion of the ten film 21 can be improved.

[0021] (Reference Example 1) FIGS. 9 (A) and 9 (B) is a sectional view showing a reference example 1 step of the present invention, this reference example, the adhesion layer 18 and titanium silicide in the first embodiment It is the same as Example 1 except that there is no step of forming the film 14. In the present reference example , the blanket tungsten film 21 serves as an adhesion layer and a barrier layer. In this reference example, similarly to the aforementioned Example 1, no reliable plug of voids can be formed.

Further, in the first embodiment and the first embodiment, the wiring is formed by the composite film of tungsten and aluminum, so that the wiring resistance is low and the high-speed operation is possible.

Although the first embodiment and the first embodiment have been described above, the present invention is not limited to these, and various design changes accompanying the gist of the configuration are possible.

For example, in Example 1 and Reference Example 1 , the P ⁺ -polysilicon film 16 was used as the upper wiring, but another wiring material layer may be used. The present invention is also applicable to a structure having

[0025]

As is apparent from the above description, according to the present invention, even when high-temperature sputtered Al is used in the plug-in vertical wiring process, a good plug can be formed without generating voids. Therefore, there is an effect that a highly reliable next-generation device can be created. Further, since the wiring is formed by a composite film of tungsten and aluminum, the wiring resistance is low and high-speed operation is possible. further,
Under the second adhesion layer, a third one capable of securing adhesion to the insulating film.
The first adhesion layer is formed, and the adhesion of the second adhesion layer is excellent.
Can be done.

[Brief description of the drawings]

FIG. 1 is an essential part cross sectional view showing a process of Embodiment 1 of the present invention;

FIG. 2 is an essential part cross sectional view showing a step of Embodiment 1 of the present invention;

FIG. 3 is an essential part cross sectional view showing a step of Embodiment 1 of the present invention;

FIG. 4 is an essential part cross sectional view showing a step of Embodiment 1 of the present invention;

FIG. 5 is an essential part cross sectional view showing a step of Embodiment 1 of the present invention;

FIG. 6 is an essential part cross sectional view showing a process of Embodiment 1 of the present invention;

FIG. 7 is an essential part cross sectional view showing a process of Embodiment 1 of the present invention;

FIG. 8 is an essential part cross sectional view showing a process of Embodiment 1 of the present invention;

FIGS. 9A and 9B are cross-sectional views of essential parts showing the steps of Reference Example 1 of the present invention.

FIG. 10 is a sectional view of a main part of a conventional example.

FIG. 11 is a sectional view of a main part of a conventional example.

FIG. 12 is a sectional view of a main part of a conventional example.

[Explanation of symbols]

10a: impurity diffusion layer (lower wiring) 14: titanium silicide film 15: first interlayer insulating film 16: P ⁺ -polysilicon film (upper wiring) 17: second interlayer insulating film 18: adhesion layer 19: connection hole for wiring 20 plug (Al) 21 blanket tungsten film

Claims (1)

(57) [Claims] An interlayer insulating film is provided on a lower wiring including a diffusion layer.
At least one upper layer wiring is formed via the film
At the same time, the top interlayer insulating film is formed on the top wiring
A connection for exposing the lower wiring to the formed structure
A plug-in that opens a hole and forms a plug in the connection hole
In the vertical wiring forming method, the uppermost interlayer insulating layer is provided before the step of forming the connection hole.
Forming a first adhesion layer on the surface of the film;
After opening, blanket as a second adhesion layer on the entire surface
A tungsten film is formed, and then the blanket tank is formed.
Aluminum-based metal in the connection hole with the gustene film
Characterized by filling with a high-temperature sputtering method
A method for forming a vertical interconnect.