JPH0355845A - Wiring forming method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a wiring forming method that is suitably implemented in integrated circuits having a so-called multilayer wiring structure. [Prior art] So-called VLSI (νery large scale
Integrated circuit: Super LS I
), etc., have conventionally used a so-called multilayer wiring structure in which multiple layers of wiring made of Al or the like are laminated with an intervening insulating film to provide three-dimensional wiring. In integrated circuits with this multi-layer wiring structure, the area for wiring can be substantially reduced, allowing for higher integration. High density. In addition to contributing to the miniaturization of chips, the average wiring length is shortened, which has the advantage of suppressing delays in operating speed due to wiring resistance. Figure 2 is a cross-sectional view showing the structure of a part of a semiconductor device such as an integrated circuit having a multilayer wiring structure. For example, Sing
A first layer of Al wiring 2 is formed on the surface of an insulating substrate #Ji1 such as, and an insulating film 3 such as Stow is formed to cover the insulating substrate l on which this An wiring 2 is formed. Then, a second layer of Al layer A4 is formed on the surface of this insulation s3. Electrical connection between the first layer A2 wiring 2 and the second layer A2 wiring 4 is made through an opening 5 called a via hole or the like formed in the insulating film 3. That is, the insulating film 3
After the formation of the opening 5, the AA wiring 4 is formed in this state by, for example, a sputtering method.
A continuous Al wiring 4 is formed from the area inside the opening 5 to the area on the surface of the insulating film 3 outside the opening 5, and in this way, the Al wiring 2.4 comes into contact with the opening 5 and is electrically connected. It will be connected. [Problems to be Solved by the Invention] FIG. 3 is an enlarged sectional view showing the vicinity of the opening 5 of the structure shown in FIG. 2, and FIG. FIG.

In VLSI and the like, the wiring width and formation area of multilayer wiring are becoming smaller, and as a result, the opening 5 has a size of about 1.0 μm square, which is about the same as the thickness of the insulating film 3. ．． When the second layer of A2 wiring 4 is formed by the sputtering method on the surface of the insulating film 3 in which the fine openings 5 are formed in this way, the bottom surface of the openings 5 is There are no Aj2 atoms attached near the periphery of
Therefore, the Ai wiring portion 4a on the bottom of the opening 5 and the opening 5
Al in the portion from the rising portion of
There is a possibility that a disconnection between the Al wiring portion 4b and the Al wiring portion 4b will occur as shown in FIG. 4, and as a result, a disconnection between the Al wirings 2 and 4 may occur. As described above, in the past, it was not possible to achieve a good electrical connection between the Affi wiring 2.4 in the first layer and the second layer in the opening 5, and as a result, when manufacturing an integrated circuit, Problems such as poor yield were occurring. The purpose of this invention is to solve the above-mentioned technical problems and provide a wired precept method that ensures reliable wiring connections. [Means for Solving the Problems] The wiring forming method of the present invention includes forming a first wiring on the surface of a substrate, forming an insulating film on the substrate on which the first wiring is formed, and forming the insulating film. selectively forming an opening in the opening to expose the first wiring; selectively forming a conductive film in the vicinity of the opening that can be softened or melted by heating; The conductive film is heated to soften or melt and fill the opening, and from this state a second wiring is formed on the surface of the insulating film so as to be in contact with the conductive film. [Operation] According to the structure of the present invention, the first and second wirings formed three-dimensionally on the substrate surface with an insulating film interposed therebetween are filled into openings selectively formed in the insulating film. electrically connected via a conductive film. This conductive film can be softened or melted by heating, and after forming the conductive film near the opening of the insulating film, by heating the conductive film, the inside of the opening can be melted. This conductive film can be filled. As a result of filling the opening of the insulating film with the conductive film, it is possible to easily make contact between the conductive film and the first wiring and between the conductive film and the second wiring. possible, thus ensuring that each electrical connection is achieved. In this way, electrical connection between the first and second wires is ensured. [Embodiment] FIG. 1 is a cross-sectional view for explaining a wiring forming method according to an embodiment of the present invention.A first wiring is formed on the surface of an insulating substrate 11 using a Stow method, for example, by sputtering. A certain first layer Al wiring l2 is formed. This Al wiring l2 has a high melting point metal coating film 12a on its surface. A Sing film 13 is formed by CVD as an insulating film on the surface of the insulating substrate 11 on which the Affi wiring 12 is formed, and an opening 14 (for example, about 1.0 μm square in size) is selectively formed in the Sing film 13. ) is formed. From this opening l4, AI! ．． The high melting point metal coating film 12a of the wiring 12 is exposed. This state is the first
This is shown in Figure (1). From this state, as a conductive film, Aflllll5 having a film thickness comparable to that of the Sing film 13 is formed by a sputtering method, and this Al film 1
5. Photoresist 16 is selectively formed on the surface using photolithography technology. This photoresist l6 is formed over the opening l4. This state is shown in Figure 1 (2). Next, the Affi film 15 is subjected to normal dry etching to leave only the portion near the opening 14 and remove the remaining portion. Thereafter, the photoresist 16 is removed, and an antireflection film 17 is formed to cover the /l film 15 left in the vicinity of the opening 14 using photolithography and etching techniques. This antireflection film 17 includes, for example, a Sins film 17a and a SiNa film 1 in order from the Al film 15 side.
It is constructed by stacking 7b and 7b. After forming the antireflection film 17, a laser beam 19 is irradiated as an energy beam toward the surface of the insulating substrate 1l. The energy of the laser beam 19 is transmitted through the anti-reflection film 17 to the AI! ．．
It is absorbed by the film 15, which heats the /l film 15 and melts or softens it.

This state is shown in FIG. 1(3). The anti-reflection film 17 is for efficiently absorbing the laser beam 19 into l 1 5, and the anti-reflection film 17 is for efficiently absorbing the laser beam 19 into l 1 5.
The film thickness of the film 17b is as follows with respect to the wavelength of the laser beam 19:
It is set to suitably act as an antireflection film. For example, when using an Ar ion laser as the laser beam 19, the main wavelengths are 514.5 nm and 488.5 nm. On
m, the thickness of the SiOz film 17a is 50 n.
m, the thickness of the SiN4 film 17b is selected to be 60 nm. The Al film 15 is melted or softened by the irradiation with the laser beam 19, so that the Al film 15 fills the opening 14 without any gaps as shown in FIG. 1(4). 1st
When the Al film 15 melts and softens due to the action of the high melting point metal coating film 12a on the surface of the Al wiring 12 in the first layer, the first
The Affi wiring 12 in the layer will not melt. As shown in FIG. 1 (1) or (2), An
When the film 15 is formed by sputtering, the A2 film 15 is difficult to adhere to the periphery of the bottom of the minute opening 14, which is approximately 1 μm square, and therefore the Al film 15 cannot completely fill the opening 14. Although it is not possible, Aj! by irradiation with the laser beam 19 as described above! After the film 15 is melted and softened, the Affi film 15 can be embedded in the opening 14 without any gaps. From the state shown in FIG. 1(4), a second layer, which is a second wiring, is formed on the surface of the insulating film 13 by sputtering, for example, so as to be in contact with the A2 film l5 embedded in the opening 14. Affi wiring 20 is formed. This state is shown in Figure 1 (5),
In this state, the /l wiring 20 of the second layer is An! llI
It is electrically connected to the first layer A2 wiring 12 via the wire 15. Moreover, since the A2 film 15 formed in the opening l4 is embedded in this opening 14 without any gaps, the A2 film 15 formed in the opening l4 is
Since the film 15 and the Al wiring 20 can be easily brought into contact, the connection between the A2 wiring 12 and 20 is reliable. In this way, according to this embodiment, the /l distribution of the first layer and the second layer! 12.20 can be reliably connected, for example, in the manufacture of integrated circuits, the circuit wiring can be reliably interconnected and the yield can be improved. In the embodiments described above, AI. Although laser light is used to heat the film 15, other energy rays such as infrared rays from an infrared lamp or heater or electron beams may be used instead of laser light.

〔Effect of the invention〕

As described above, according to the wiring type precept method of the present invention, in the insulating film formed between the first wiring and the second wiring,
Since the opening formed for the connection between the first and second wirings is filled with a conductive film, the electrical connection between the first and second wirings is established in this way. The precepts will be reliably achieved through the conductive film. As a result,
For example, in the manufacture of semiconductor devices such as integrated circuits, it becomes possible to connect circuit wiring reliably and to significantly improve yields.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view for explaining a wiring forming method according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the structure of a part of an integrated circuit having a conventionally used multilayer wiring structure. 3 is an enlarged sectional view showing the vicinity of the opening 5 shown in FIG. 2, and FIG. 4 is a plan view showing the Affi wiring 4 expanded. 11... Insulating substrate (substrate), 12...
First layer Al wiring (first wiring), l3...SiO
Z film (insulating film) l4...opening, 15...Al film (
Conductive film), 17... Anti-reflection film, 19... Laser light, 20... Second layer wiring (second wiring) Voice 1 Figure

Claims (1)

[Claims] A first wiring is formed on the surface of a substrate, an insulating film is formed on the substrate on which the first wiring is formed, and an opening is selectively formed in this insulating film. The first wiring is exposed at the opening, a conductive film that can be softened or melted by heating is selectively formed in the vicinity of the opening, and the conductive film is heated to soften or melt. A wiring forming method, comprising: filling the opening, and from this state forming a second wiring on the surface of the insulating film so as to be in contact with the conductive film.