JP2648134B2 - Semiconductor device and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, to a semiconductor device having an antifuse element formed in a semiconductor integrated circuit and a method of manufacturing the same.

[0002]

2. Description of the Related Art An antifuse element is an FPGA (Field Programmable Gate Array).
Programmable Gate Array)
Are formed in an integrated circuit to constitute a logic cell of a user-programmable logic device or a memory cell of a PROM.

Here, the antifuse element is a fuse element which is open in an initial state and becomes conductive by a write operation, contrary to a normal blown fuse element.

FIG. 2 shows a conventional antifuse element (first conventional example).

[0005] The antifuse element is a semiconductor substrate 1
First aluminum film wirings 3-1 and 3-2 for selectively covering first insulating film 2 above, and interlayer insulating film 4 having contact hole 5-1 reaching first aluminum film wiring 3-1. The amorphous silicon film 6 (having a thickness of 100) contacting the first aluminum film wiring 3-1 at the bottom of the contact hole 5-1.
nm) and the amorphous silicon film 6 and the interlayer insulating film 4
Of the second aluminum film wiring 7 which selectively covers In the initial state, the first aluminum film wiring 3-1 and the second aluminum wiring 7 are non-conductive by the amorphous silicon film 6, but the first aluminum film wiring 3-1 and the second aluminum film wiring A voltage is applied between the amorphous silicon film 7 and the amorphous silicon film 6 to reduce the resistance by Joule heat.

However, in this antifuse element, the aluminum film and the amorphous silicon film are in direct contact with each other. It has the disadvantage of being lost. This drawback can be avoided by forming upper and lower wirings in contact with the amorphous silicon film with a high melting point metal film or an alloy film thereof as disclosed in Japanese Patent Application Laid-Open No. 5-90411. . However, a high melting point metal film or the like has a higher electric resistance than an aluminum film.
Therefore, a technique (second conventional example) of forming a barrier film between an aluminum film and an amorphous silicon film is described in the above-mentioned publication.

That is, as shown in FIG. 3A, a first aluminum film having a high melting point metal film 8 of tungsten, molybdenum or the like on its surface selectively covered with a first insulating film 2 on a semiconductor substrate 1 is formed. The film wirings 3-1A and 3-2A are formed. Next, as shown in FIG. 3B, an interlayer insulating film 4A such as PSG is formed, contact holes 5-1A and 5-2A are formed, and a contact hole 5-1A and a thickness of 100 nm are formed in the vicinity thereof.
An amorphous silicon film 6A is formed. Next, FIG.
As shown in (c), the surface and side surfaces of the amorphous silicon film 6A are covered with a tungsten film 9. Next, FIG.
As shown in FIG. 7, a second aluminum film wiring 7A is formed.

[0008]

In the conventional example described with reference to FIG. 3, since a high-melting point metal film such as a tungsten film exists as a barrier film between the aluminum film and the amorphous silicon film, aluminum is not used. Since silicon is prevented from interdiffusion and an aluminum film having low electric resistance is used for the wiring, a semiconductor device suitable for high-speed operation can be realized.

However, as is apparent from FIG. 3, since the ends of the amorphous silicon film 6A and the tungsten film 9 are located on the surface of the interlayer insulating film in the vicinity of the contact hole, a step is formed due to this. Therefore, there is a problem in that flatness, which is increasing in importance as the multi-layer wiring of the semiconductor device progresses, is hindered.

There is also a problem that the manufacturing process is complicated because the barrier film is formed.

In the above description, the same can be said for a wiring using an aluminum-based alloy film consisting only of an aluminum film (hereinafter, these are collectively referred to as aluminum-based wiring).

Accordingly, it is an object of the present invention to provide a semiconductor device having an antifuse element having good flatness and capable of using aluminum-based wiring without complicating the process, and a method of manufacturing the same.

[0013]

According to the present invention, there is provided a semiconductor device comprising:
A first aluminum-based wiring that selectively covers a first insulating film on a semiconductor substrate, a contact hole that reaches the first aluminum-based wiring, a silicon nitride film, and a silicon nitride film formed by a coating method and heat treatment; An interlayer insulating film including a second insulating film; a third insulating film formed on the surface of the first aluminum-based wiring at the bottom of the contact hole by the heat treatment; and a third insulating film at the contact hole portion And an antifuse element formed of a second aluminum-based wiring selectively connected to the first aluminum-based wiring through the interlayer insulating film.

Here, the second insulating film can be preferably a polyimide film.

Further, according to the method of manufacturing a semiconductor device of the present invention, a first aluminum-based wiring for selectively covering a first insulating film on a semiconductor substrate is formed, a silicon nitride film is deposited, and then the insulating film is formed. A coating liquid for forming is applied, converted into a cured film by a first heat treatment, a contact hole reaching the first aluminum-based wiring is formed by a dry etching method, and a second heat treatment is performed at a higher temperature than the first heat treatment. To form an interlayer insulating film by using the cured film as a second insulating film, and to form the first insulating film at the bottom of the contact hole.
Forming a third insulating film on the surface of the aluminum-based wiring by the gas released from the cured film, and connecting to the first aluminum-based wiring at the contact hole via the third insulating film. The method includes forming an antifuse element for forming a second aluminum-based wiring covering the interlayer insulating film.

Here, it is preferable that a coating liquid for forming a polyimide film can be applied and converted into a cured film by imidization by a first heat treatment. It is also possible to perform a pre-bake for evaporating the solvent contained in the liquid and then vitrify it to some extent by the first heat treatment to convert it into a cured film.

[0017]

The third fuse of the antifuse element is formed on the surface of the first aluminum-based wiring during heat treatment for forming an interlayer insulating film.
Is formed, the third insulating film is not formed on the interlayer insulating film in the vicinity of the contact hole.

Further, the third insulating film can be formed at the time of heat treatment for forming the interlayer insulating film without requiring a barrier film.

[0019]

Next, an embodiment of the present invention will be described.

First, as shown in FIG. 1A, a first insulating film 2 (field oxide film or oxide film) on a semiconductor substrate 1 made of silicon (on which electronic elements such as MOS transistors not shown are formed) is formed. The first aluminum-based wirings 10-1 and 10-1 are formed on the surface of a silicon-based interlayer insulating film or the like.
-2 (made of a pure aluminum film or an aluminum-based film such as an Al-Si-Cu alloy film).

Next, as shown in FIG. 1B, a silicon nitride film 11 having a thickness of 150 nm is formed by a plasma CVD method, and a coating liquid for forming a polyimide film, for example, PSI-N- 6001 and 250 ° C
By a first heat treatment for 30 minutes, the film is imidized to some extent to form a cured film 12 having a thickness of 1.5 μm. Next, a contact hole 5-1B reaching the first aluminum-based wiring 10-1 by isotropic reactive ion etching using CF ₄ gas using a photoresist film (not shown) as a mask.
(Opening area of about 1 μm × 1 μm) is formed. Next, the above-mentioned photoresist film is removed, and a second heat treatment is performed at 400 ° C. for 30 to 60 minutes, whereby the hardening of the hardened film 12 proceeds to form a polyimide film 12a (third insulating film). .
During the second heat treatment, the moisture or organic solvent contained in the cured film 12 evaporates and reacts with air or aluminum to form a third insulating film 13 having a thickness of about 60 nm. Next, as shown in FIG. 1D, a contact hole reaching the first aluminum-based wiring 10-2 by isotropic reactive ion etching using CF ₄ gas using a photoresist film (not shown) as a mask. 5-2B is formed, the above-described photoresist film is removed, and a second aluminum-based wiring 14 is formed. Thereafter, if necessary, an interlayer insulating film or a cover film is further formed.

In this manner, the first aluminum-based wiring 8 selectively covering the first insulating film 2 on the semiconductor substrate 1
-1A, a contact hole 5-1B reaching the first aluminum-based wiring 10-1, a silicon nitride film, and a second insulating film (polyimide film 12) formed by a coating method and heat treatment.
a) the third insulating film 13 formed on the surface of the first aluminum-based wiring 8-1A at the bottom of the contact hole 5-1B and the contact hole 5-1B at the bottom of the contact hole 5-1B. A semiconductor device including an antifuse element including a second aluminum-based wiring 14 that is connected to a first aluminum-based wiring 10-1 via a third insulating film 13 and selectively covers the above-described interlayer insulating film is provided. can get.

In the initial state of the antifuse element thus formed, the antifuse element has a resistance of about 1000 MΩ and shows a good non-conductive state, and can be made conductive by applying a voltage of 10 to 15 volts. Was.

Since the polyimide film 12a is formed by using a coating method, an interlayer insulating film having excellent flatness can be formed as compared with the BPSG film. Further, the formation of the third insulating film allows the vicinity of the periphery of the contact hole 5-1B to be formed. As a result, the interlayer insulating film did not become particularly thick. Therefore, a semiconductor device with few steps and good flatness can be realized. In addition, since the third insulating film 13 is formed by using the second heat treatment necessary for forming the polyimide film, the process does not become complicated.

In this embodiment, the contact hole 5-2B on the first aluminum-based wiring 10-2 is
Although the opening was formed after the formation of the contact hole 5-1B, the opening may be formed simultaneously with the contact hole 5-1B in the state of the cured film 12. In that case,
By the second heat treatment, the first aluminum-based wiring 10-
The third insulating film is also formed on the surface of the substrate 2, which may be removed by forming a mask made of a photoresist film and performing reactive ion etching with CF ₄ gas.

Further, an SOG film can be used instead of the polyimide film. For example, a coating liquid for forming an SOG film containing silanol such as Si (OH) ₄
Pre- and post-baking is performed, and a first heat treatment at about 250 ° C. is performed to form a cured film by vitrification to a certain degree.
The second heat treatment may be performed before and after to complete the vitrification and to make the film dense.

Further, it goes without saying that the thickness of the third insulating film can be controlled by the temperature, time and atmospheric pressure of the second heat treatment.

Further, the second insulating film contains a large amount of moisture and a solvent in a state of being cured by the first heat treatment, such as a polyimide film and an SOG film, and is formed by the second heat treatment in a later step. Any material that can form an insulating film on the surface can be used.

[0029]

As described above, according to the present invention, a first aluminum-based wiring is formed, a silicon nitride film is deposited, a coating liquid for forming an insulating film is applied, and the contact is formed after being cured by a first heat treatment. By forming the hole and performing the second heat treatment, an interlayer insulating film having good flatness can be formed, and at the same time, the third insulating film of the antifuse element can be formed at the bottom of the contact hole. An antifuse element having an electrode wiring with low electric resistance can be manufactured in a semiconductor device without causing deterioration. Therefore, it is possible to contribute to a further increase in the number of multilayer wirings, an increase in speed, and a reduction in cost of a semiconductor device including an antifuse element.

[Brief description of the drawings]

FIGS. 1A to 1D are cross-sectional views in the order of steps for explaining one embodiment of the present invention.

FIG. 2 is a sectional view showing a first conventional example.

FIGS. 3A to 3C are views for explaining a second conventional example.
It is a process order sectional view divided and shown to (d).

[Explanation of symbols]

Reference Signs List 1 semiconductor substrate 2 first insulating film 3-1 3-1A, 3-2, 3-2A first aluminum film wiring 4 interlayer insulating film 5-1 5-1A, 5-1B, 5-2 5-2A, 5-
2B Contact hole 6, 6A Amorphous silicon film 7, 7A Second aluminum film wiring 8 Refractory metal film 9 Tungsten film 10-1, 10-2 First aluminum-based wiring 11 Silicon nitride film 12 Cured film 12a Polyimide Film 13 third insulating film 14 second aluminum-based wiring

Claims (5)

(57) [Claims] A first aluminum-based wiring for selectively covering a first insulating film on a semiconductor substrate; a silicon nitride film having a contact hole reaching the first aluminum-based wiring; An interlayer insulating film including a second insulating film formed by the heat treatment; a third insulating film formed on the surface of the first aluminum-based wiring at the bottom of the contact hole by the heat treatment;
An anti-fuse element comprising a second aluminum-based interconnection selectively connected to the first aluminum-based interconnection via the third insulation film at the contact hole portion with the first aluminum-based interconnection at the contact hole portion A semiconductor device comprising: 2. The semiconductor device according to claim 1, wherein the second insulating film is a polyimide film. 3. A first aluminum-based wiring for selectively covering the first insulating film on the semiconductor substrate is formed, a silicon nitride film is deposited, and then a coating liquid for forming an insulating film is applied. Forming a contact hole reaching the first aluminum-based wiring by a dry etching method, and performing a second heat treatment at a higher temperature than the first heat treatment to form the cured film into a second insulating film. Forming an interlayer insulating film by forming a film, and forming a third insulating film on a surface of the first aluminum-based wiring at a bottom portion of the contact hole by a gas released from the cured film;
An antifuse element forming step of forming a second aluminum-based wiring covering the interlayer insulating film by connecting to the first aluminum-based wiring through the third insulating film at the contact hole portion. A method for manufacturing a semiconductor device. 4. The method for manufacturing a semiconductor device according to claim 3, wherein a coating liquid for forming a polyimide film is applied and is converted into a cured film by imidization by a first heat treatment. 5. The method according to claim 3, wherein a coating liquid for forming the SOG film is applied, prebaking is performed to evaporate a solvent contained in the coating liquid, and then a certain degree of vitrification is performed by a first heat treatment to convert the film into a cured film. A method for manufacturing a semiconductor device.