JPS63147346A - Semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To obtain the title semiconductor integrated circuit device of the multilayer wiring structure with which the resistance component due to a through-hole does not increase by a method wherein the aluminum wiring on the lower layer and the aluminum wiring on the upper layer are connected through the intermediary of a layer consisting of high melting point metal or a film consisting of either of a silicide and a nitride of high melting point metal. CONSTITUTION:The aluminum wiring 6 located on the lower layer and the aluminum wiring 11 located on the upper layer of multilayer aluminum wiring structure are connected through the intermediary of a layer 13 consisting of high melting point metal or a layer consisting of either of a silicide and a nitride of high melting point metal. The above-mentioned high melting point metal consists of one or more kinds of tungsten, molybdenum or titanium, for example. For example, after an interlayer insulating film 9, consisting of a silicon nitride film, has been grown by deposition on the first aluminum wiring 6, a through-hole 10 is perforated. Then, a tungsten silicide layer 13 is coated on the whole surface by performing a sputtering method, then aluminum layer 11 is sputtered, and besides, a wiring patterning performed by selectively etching the tungsten silicide layer 13 and the aluminum layer 11 at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor integrated circuit device, and more particularly to a connection structure between multilayer aluminum interconnections.

[Prior Art, 1] As the degree of integration of semiconductor integrated circuit devices increases, miniaturization of wiring patterns and multilayer technology are becoming more and more important. Conventionally, aluminum has been selected as the main wiring material, but even though it has problems such as the occurrence of "hillocks" and electromigration, it has low resistance and is stable for thin horizontal wiring. This is because it can be formed into

FIG. 5 is a partial sectional view of an aluminum wiring portion of a conventional two-layer wiring structure semiconductor integrated circuit device. According to the wiring structure shown in FIG. 5, the first layer aluminum wiring 6 formed on the interlayer insulation wA4 is connected to the impurity diffusion layer 3 on the silicon substrate 1 and the field insulation film 2 through the contact holes 5 and 8. The second layer aluminum wiring 11 is connected to the first layer aluminum wiring 6 through a through hole 10 provided in the interlayer insulation WA9. In this case, in general, the thickness of the first layer of aluminum wiring 6 is made thin to keep the level difference low, while the thickness of the second layer of aluminum wiring 11 is made thick to improve the level difference coverage. At the same time, a heat treatment process is performed to utilize the large mutual diffusion coefficient between aluminum and silicon to increase the degree of adhesion between the two in the contact hole. That is, since aluminum has a silicon solid solubility of 2 to 3% at a temperature of 450°C,
When heat treatment is performed at approximately 00° C., aluminum and silicon react violently at the interfaces of contact holes 5 and 8 and interdiffuse, making it possible to form contact portions with extremely high reliability.

Therefore, today aluminum pre-contained with 1 to 2% silicon is widely used as a wiring material.

[Problem that the invention seeks to solve]

In this manner, in the conventional two-layer wiring structure, the first and second layer aluminum wirings 6 and 11 are directly connected via the through hole 10. Therefore, even after the silicon diffused by the heat treatment becomes saturated in the first layer aluminum wiring 6, it continues to diffuse into the second layer aluminum wiring 11 through the through hole 10. The silicon diffused during this heat treatment eventually recrystallizes locally at the contact portion of the through ball, or precipitates within the aluminum wiring due to oversaturation after the heat treatment.

FIG. 6 is a diagram showing the state of silicon precipitation inside through holes and aluminum wiring caused by heat treatment of a conventional wiring structure, and 12a and 12b are deposited silicon layers. If a precipitated silicon layer 12b is formed in the wiring, especially in the entire contactor area of the through hole, the precipitated silicon is a substance with high electrical resistance, so the resistance of the through hole increases, causing electrical discontinuity between the aluminum wiring. The problem arises that the connection is poor.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a semiconductor integrated circuit device having a multilayer aluminum wiring structure that does not increase the resistance of through holes due to a wiring heat treatment process.

[Means for solving problems]

According to the present invention, in a semiconductor integrated circuit device having a multilayer aluminum wiring structure, a layer between a lower layer aluminum wiring and an upper layer aluminum wiring is a high melting point metal or a high melting point metal. This includes being connected through a layer made of one material selected from silicide and nitride.

Here, the high melting point metal is tungsten (W).

This includes cases where it is made of either one of molybdenum (Mu) and titanium ('r'i) or a combination thereof.

According to the present invention, a layer made of at least one substance such as a high melting point metal or a silicide or nitride of a high melting point metal acts as a barrier layer that suppresses the diffusion of silicon at the connection portion between two upper and lower aluminum wirings. This makes it possible to prevent electrical connection failures in contact holes due to silicon diffusion and maintain electrical connection between aluminum wirings.

〔Example〕

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view of a through-hole portion showing an embodiment of the present invention. According to this embodiment, the semiconductor integrated circuit device of the present invention includes the first layer of aluminum wiring 6, the glabella insulating film 9,
Through hole 10 provided by opening interlayer insulating film 9
, a silicide layer 13 of a high melting point metal that covers the inside of the opening of the through hole 10 , and a silicide layer 13 of a high melting point metal that connects the first layer aluminum wiring 6 to the through hole 1 .
0, and a second layer of aluminum wiring 11 connected within 0. Here, tungsten, titanium molybdenum, etc. can be used as the high melting point metal. The connection between the wirings can be formed as follows. That is, first, plasma CV is applied to the first layer of aluminum wiring 6 formed by known means.
After a glabellar insulating film 9 made of a silicon nitride film is deposited and grown using method D, through holes 10 are formed by selectively etching the glabellar insulating film 9 in CF4 gas plasma. Next, a tungsten silicide layer with a thickness of about 0.1 μm, for example, is deposited on this entire surface by sputtering, followed by a sputtering of an aluminum layer with a thickness of 0.5 μm, and then a CC1-based gas plasma is applied using a photoresist as a mask. If wiring patterning is performed in which the tungsten silicide layer and the aluminum layer are selectively etched at the same time, the wiring structure shown in FIG. 1 can be obtained. Next, to ensure contact, the temperature in the nitriding atmosphere was 40°C.
Heat treatment is performed for 9 hours and 60 minutes at 0°C, but since the tungsten silicide layer 13 has a small barrier effect against silicon diffusion, the silicon diffused from the silicon layer into the aluminum wiring during this heat treatment is transferred from the first layer of aluminum wiring 6 to the aluminum wiring. 2
It also diffuses into the aluminum wiring 11 of the layer.

FIG. 2 is a diagram showing the state in which precipitated silicon layers are generated by heat treatment of multilayer aluminum wiring according to the present invention. Precipitated silicon layers 12a and 12b appear inside the wiring of each layer and also inside the through hole 10. . However, even if it occurs inside the through hole 10 as shown in FIG. 2, the inner wall of the through hole 10 is entirely covered with the tungsten silicide layer 13, so the two aluminum wiring 6 and 11 can be completely maintained.

FIG. 3 is a sectional view of a through hole section showing another embodiment of the present invention. According to this embodiment, a titanium nitride layer 14 is used in place of the tungsten silicide layer as a barrier layer against silicon diffusion. This barrier layer is also formed by the sputtering method to a thickness of about 1.1 μm, but since the barrier effect of the titanium nitride layer 14 is very strong, the precipitated silicon layer is hardly inside the second layer aluminum wiring 11. Does not occur.

FIG. 4 is a sectional view of a through hole section showing another embodiment of the present invention.

According to this embodiment, the molybdenum silicide layer 15 is used as a barrier layer and is formed only on the sidewalls of the through hole 10 except for the bottom surface. To obtain this side path, a molybdenum silicide film with a thickness of 0.3 μm is formed by sputtering as in the previous example, and then the entire surface is anisotropically etched in a CCl4 gas plasma. After leaving the silicide 15, an aluminum layer of 0.5 μm was formed by sputtering in the same way.
The film was formed to a thickness of m, and the second
The layered aluminum wiring 11 may be formed by patterning. In this example, the connection between the two aluminum wirings is partly done through molybdenum silicide [15] and the other parts are made by direct adhesion of the aluminum wirings, so the initial contact is good. Further, it has the advantage that connection failures due to the deposited silicon layer do not occur even after heat treatment.

As is clear from the above description, the barrier layer against silicon precipitation in the present invention can be formed of either a silicide layer or a nitride layer of a high-melting point metal, and is not limited to the material used. The structure of the embodiment shown in FIG. 4 is effective when a barrier layer having a relatively large initial connection resistance is used, such as the barrier layer shown in FIG. Also,
It is of course possible to use a single high-melting point metal, and even a combination of a plurality of metals can be easily implemented.

Furthermore, it is clear that the interlayer insulating film does not need to be a plasma nitride film, and may be any insulating film that can be generally used in semiconductor devices, such as a silicon oxide film.

〔Effect of the invention〕

As explained in detail above, according to the present invention, a layer made of a refractory metal or at least one substance of silicide or nitride of a refractory metal is formed in part or all of the connection region of a multilayer aluminum wiring. By doing so, it is possible to suppress the diffusion and precipitation of silicon at the connection part, or to ensure electrical continuity between the upper layers of the aluminum wiring through the layer made of these substances even if temporary precipitation occurs. Through
It can sufficiently cope with the miniaturization of holes, and can have a great effect on achieving a higher degree of integration and improving reliability of semiconductor integrated circuit devices.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a through-hole portion showing an embodiment of the present invention, FIG. 2 is a diagram showing the state of formation of a precipitated silicon layer due to heat treatment of multilayer aluminum wiring according to the present invention, and FIG. FIG. 4 is a cross-sectional view of a through-hole portion showing another embodiment of the present invention, and FIG. 5 is a conventional two-layer wiring structure semiconductor integrated circuit device. FIG. 6 is a partial cross-sectional view of the aluminum wiring portion of FIG. 6, which shows the state of silicon precipitation inside the through holes and inside the aluminum wiring caused by heat treatment of the conventional wiring structure. 6... First layer aluminum wiring, 9... Interlayer insulating film, 1
0... Through hole, 11... Second layer aluminum wiring, 12a, 12b... Precipitated silicon layer, 13...
Tungsten silicide layer, 14...Titanium nitride layer, 1st layer (8z prisoner t) IIJ layer (1) A 17/Yeetsu1 layer
13: Kunqmeden, Tanozu 4-Kushi layer Chichisu 11/-'Water -7
/, 5 Llatte> Nisozuite 2ψIf-105Z layer aluminum cover

Claims (2)

[Claims] (1) In a semiconductor integrated circuit device having a multilayer aluminum wiring structure, the material between the lower layer aluminum wiring and the upper layer aluminum wiring is selected from a high melting point metal, a silicide or a nitride of a high melting point metal. A semiconductor integrated circuit device characterized by being connected through a layer made of one substance. (2) Claim (1) characterized in that the high melting point metal is made of any one of tungsten (W), molybdenum (Mo), and titanium (Ti) or a combination thereof. semiconductor integrated circuit devices.