JP2890419B2 - Manufacturing method of semiconductor integrated circuit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a semiconductor integrated circuit, and more particularly to a method for manufacturing a semiconductor integrated circuit having an electrode wiring structure containing aluminum as a main component.

[Conventional technology]

Conventionally, the electrode wiring of this type of semiconductor integrated circuit is a barrier metal layer that prevents a mutual diffusion of silicon and avmium by a sputtering method after forming a predetermined contact hole in an insulating film covering the surface of a semiconductor substrate on which elements are formed. Is formed, and after an aluminum-silicon alloy film is applied, the aluminum-silicon alloy and the barrier metal layer are patterned into a predetermined shape. FIG. 3 is a sectional view of an aluminum electrode wiring formed on a silicon substrate 21 partitioned by a field oxide film 2 by a conventional method. The titanium / tungsten alloy film 4 is used as a barrier metal layer.

[Problems to be solved by the invention]

In the conventional method for manufacturing a semiconductor integrated circuit described above,
As shown in the drawing, when the contact hole provided in the field oxide film 2 on the silicon substrate 1 becomes smaller, the titanium-tungsten alloy film 3 formed by the sputtering method becomes smaller.
Does not enter the contact hole, and even if the aluminum / silicon alloy film 4 is subsequently applied, the aluminum / silicon alloy film 4 does not enter the contact hole, resulting in a disconnection.

Even if the aluminum / silicon alloy film 4 is applied so as to enter the contact hole by a bias sputtering method or the like, the titanium / tungsten alloy film 3 is not applied to the contact hole. Reacts with the aluminum / silicon alloy film 4 to destroy the element.

An object of the present invention is to provide a method of manufacturing a semiconductor device which can make good contact without such a problem even if the contact hole becomes small.

[Means for solving the problem]

The method of manufacturing a semiconductor integrated circuit according to the present invention comprises the steps of: forming a refractory metal nitride film as a barrier metal layer for preventing interdiffusion of silicon and aluminum on a diffusion layer of a silicon substrate; and forming an insulating film; Forming a contact hole on the bottom surface of the insulating film where only the refractory metal nitride film is exposed; depositing a polycrystalline silicon film, filling the contact hole with silicon, and placing the polycrystalline silicon film on the insulating film; Forming an aluminum film while leaving the polycrystalline silicon film and the aluminum film, patterning the two-layer film of the polycrystalline silicon film and the aluminum film, and reacting the polycrystalline silicon and the aluminum film by heat treatment to form an alloy. And

〔Example〕

 Next, the present invention will be described with reference to the drawings.

1 (A) to 1 (H) are cross-sectional views of semiconductor chips arranged in the order of steps for explaining a first embodiment of the present invention.

A titanium film 16 is applied by sputtering to a thickness of 20 to 200 nm on the entire surface of the silicon substrate 101 where the elements are separated by the field oxide film 102 and the diffusion layer (not shown) is exposed (FIG. 1A). ). Next, with a halogen lamp, in an ammonia atmosphere at a temperature of 600 to 800 ° C for 30 to 120
The surface on the diffusion layer is heat-treated for 2 seconds to form a titanium silicide film 107 and a titanium nitride film 108 from below, and the upper surface of the field oxide film 12 is a titanium nitride film 108 (first
FIG. Next, after the titanium nitride film 108 is removed with an aqueous solution of ammonia and hydrogen peroxide, heat treatment is performed again in an ammonia atmosphere to form the titanium silicide film 10.
A titanium nitride film on the surface of No. 7 is formed (FIG. 1 (C)). The nitriding of the surface of the titanium silicide film 107 can be performed by high frequency plasma in an ammonia atmosphere. Next, a phosphosilicate glass (PSG) film 103 is formed on the entire surface of the silicon substrate 11 by the CVD method.
Contact hole 1 reaching titanium nitride film 109 in PSG film 103
10 are provided (FIG. 1 (D)). Next, a polycrystalline silicon film 111 is formed over the entire surface of the silicon substrate 101 by a low pressure CVD method so as to have a thickness of at least half the diameter of the opening, and the opening is buried with polycrystalline silicon (FIG. 1 ( E)). Next, silicon substrate
The polycrystalline silicon film 111 on the substrate 101 is etched until the surface of the PSG film 103 is exposed (FIG. 1F), and an aluminum alloy film 112 containing about 1% of copper and about 0.5% of silicon.
Is formed by a sputtering method, and then patterned into a predetermined shape using a normal lithography technique (FIG. 1 (G)). Finally, 400-500 ℃ to stabilize the device
At a temperature of about 10 to 30 minutes. At this time, the polycrystalline silicon of the contact hole and the aluminum alloy correspond and integrate, and the opening is buried with the aluminum alloy (112 ') (FIG. 1 (H)).

FIGS. 2A to 2E are cross-sectional views of semiconductor chips arranged in the order of steps for explaining a second embodiment of the present invention. As in the first embodiment, a titanium-tungsten alloy is sputtered in a mixed atmosphere of argon and nitrogen on the entire surface of the silicon substrate 201 in which the elements are separated by the field oxide film 202 and the diffusion layer (not shown) is exposed. A tungsten alloy film 213 is formed to a thickness of 50 to 200 nm, and the titanium nitride-tungsten alloy film 21 is formed.
3 is then selectively removed so as to remain only in the periphery where the contact hole is formed (FIG. 2A). Next, after forming a PSG film 203 over the entire surface of the silicon substrate 201 by the CVD method,
A contact hole 210 reaching the titanium nitride-tungsten alloy film 213 is formed in the SG film 203 (FIG. 2 (B)). Next, the polycrystalline silicon film 211 is deposited on the silicon substrate by a low pressure CVD method.
After forming a film having a thickness of at least half the diameter of the contact hole over the entire surface of 201 and embedding the contact hole with polycrystalline silicon,
Etching is performed until the thickness of the polycrystalline silicon film at the flat portion becomes several tens of nanometers (FIG. 2C). Next, after pure aluminum is sputtered to a thickness of about 1 μm to form an aluminum film 214, the pure aluminum film 214 and the polycrystalline silicon film 211 are continuously etched using a normal lithography technique and patterned into a predetermined shape. (FIG. 2 (D)). Finally, to stabilize the device,
A heat treatment at 500 ° C. is performed. At this time, the polycrystalline silicon reacts with pure aluminum to form an aluminum-silicon alloy film 215.
The electrode wiring is formed by the aluminum / silicon alloy film (FIG. 2 (E)).

In the above description, a titanium silicide film-titanium nitride film two-layer film and a titanium nitride-tungsten alloy film have been described as examples of barrier metal layers. A metal silicide nitride film or a combination thereof can be used.

[Effects of the Invention] As described above, the present invention forms a barrier metal layer for preventing interdiffusion of silicon and aluminum on a diffusion layer of a semiconductor substrate, and then forms an insulating film. By providing a contact hole reaching the metal, burying the contact hole with polycrystalline silicon, applying pure aluminum or an aluminum alloy and forming an electrode wiring, even if the diameter of the contact hole provided in the insulating film is reduced, Since the contact holes can be buried and flattened with an aluminum alloy, the connection of the elements formed in the semiconductor substrate can be ensured, and further, for example, the second and third layer aluminum electrode wiring and passivation film can be easily formed. It has the following effects.

In addition, there is a barrier metal layer between the semiconductor substrate and the aluminum alloy, and since the barrier metal layer is formed before the insulating film is formed on the semiconductor substrate, the diameter of the contact hole provided in the insulating film is small. Even after that, a sufficient barrier property can be secured, and there is also an effect that there is no possibility that the element is destroyed by aluminum.

[Brief description of the drawings]

FIGS. 1A to 1H are cross-sectional views of a semiconductor chip arranged in a process order for explaining a first embodiment of the present invention.
4A to 4E are cross-sectional views of semiconductor chips arranged in the order of steps for explaining a second embodiment of the present invention, and FIG. 3 is a cross-sectional view of a semiconductor chip for explaining a conventional example. . 1,101,201: silicon substrate, 2,102,202 ... field oxide film, 3,103,203 ... PSG film, 4 ... titanium / tungsten alloy film, 5 ... aluminum / silicon alloy film, 10
6 ... titanium film, 107 ... titanium silicide film, 108, 109 ... titanium nitride film, 110, 210 ... contact hole, 111, 211 ... polycrystalline silicon film, 112, 112 '...
Aluminum alloy film, 213: titanium nitride / tungsten alloy film, 214: pure aluminum film, 215: aluminum / silicon alloy film.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 21/28-21/288 H01L 29/41-29/45 H01L 21/3205

Claims (5)

(57) [Claims] A step of forming a refractory metal nitride film as a barrier metal layer on a diffusion layer of a silicon substrate as a barrier metal layer for preventing mutual diffusion of silicon and aluminum, and then forming an insulating film; Forming a contact hole exposing only the refractory metal nitride film; and depositing a polycrystalline silicon film, filling the contact hole with silicon, and forming an aluminum film while leaving the polycrystalline silicon film on the insulating film. Patterning the two-layer film of the polycrystalline silicon film and the aluminum film after the formation, and reacting the polycrystalline silicon and the aluminum film by heat treatment to form an alloy. Production method. 2. A high melting point metal film is deposited on a diffusion layer of a silicon substrate, a high melting point metal silicide film is formed by heat treatment, and then nitrided by high frequency plasma in an ammonia atmosphere to prevent mutual diffusion of silicon and aluminum. Forming a barrier metal layer to be formed, and then forming an insulating film, and forming a contact hole in the insulating film at the bottom surface of which only the barrier metal film is exposed,
Depositing a polycrystalline silicon film, filling the contact hole with silicon, forming an aluminum film while leaving the polycrystalline silicon film on the insulating film, and then patterning the two-layer film of the polycrystalline silicon film and the aluminum film; And reacting the polycrystalline silicon and the aluminum film by heat treatment to form an alloy. 3. The method according to claim 2, wherein the refractory metal film is a titanium layer. 4. A barrier metal layer for preventing mutual diffusion of silicon and aluminum by forming a refractory metal nitride by sputtering a refractory metal in a mixed atmosphere of argon and nitrogen on a diffusion layer of a silicon substrate. Forming an insulating film, then forming an insulating film, forming a contact hole in the insulating film on the bottom surface of the barrier metal film only, and depositing a polycrystalline silicon film on the insulating film to form the contact hole. Is embedded in silicon, an aluminum film is formed while the polycrystalline silicon film is left on the insulating film, and then a two-layer film of the polycrystalline silicon film and the aluminum film is patterned, and the polycrystalline silicon and the aluminum film are heat-treated. And reacting the alloy to form an alloy. 5. The method according to claim 4, wherein the titanium-tungsten alloy film is formed using a titanium-tungsten alloy as the refractory metal.