JPH065712A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a wiring in a connecting hole, wherein it does not cause a short circuit between wirings and its reliability is high. CONSTITUTION:A connecting hole 26 is made in an insulating film 25 which has been applied onto a semiconductor substrate 20; wirings 27, 28 are formed respectively on the insulating film 25 and in the connecting hole 26; an insulating film 29 is buried separately between the wirings 27, 28; at least the wiring 28 is heated. Thereby, the interconnection 28 inside the connecting hole 26 is made fluid and buried. Thereby, it is possible to manufacture a semiconductor device in which the fluidity of the wirings to the transverse direction is suppressed, in which the short circuit between the wirings is prevented and whose yield is high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device manufacturing method capable of forming a multi-layered wiring having high reliability.

[0002]

2. Description of the Related Art In recent years, with miniaturization and high integration of semiconductor devices, reliability of wiring, that is, electromigration and stress migration has become a problem.
As the wiring material, pure Al deposited by using a sputtering method, or Si, Ti, Cu, Ge, Hf, B, P
An Al alloy containing d or the like is used.

As a conventional method of forming a multilayer wiring in a semiconductor device, as shown in FIG. 3, a first connection hole 3 is formed in a first insulating film 2 formed on a semiconductor substrate 1, and After forming the first wirings 4 and 5 on the first connection hole 3 and the first insulating film 2, respectively, a second insulating film 6 is deposited on them and planarized. Then, after forming the second connection hole 7 in the second insulating film 6,
A method has been used in which the second wirings 8 and 9 are formed on the second insulating film 6 and the second connection hole 7, respectively, and finally the protective film 10 is formed thereon.

However, with the miniaturization and higher integration of semiconductor devices, the ratio of the depth of the connection hole to the diameter of the connection hole (aspect ratio) becomes higher. As a result, the reliability of the wiring deposited by the sputtering method is that the step coverage (step coverage) in the connection holes 3 and 7 deteriorates, which leads to disconnection at an early stage or electromigration or stress migration. There was a problem above.

As a method for solving the above problems,
As shown in FIG. 4A, the second substrate is formed on the semiconductor substrate 11.
Second insulating film 16 having a connection hole 17 is formed, and second wirings 18 and 19 made of an Al alloy are formed on the second insulating film 16 and in the second connection hole 17, respectively,
As shown in FIG. 4B, there is a method of irradiating a laser beam L to heat the second wirings 18 and 19 so that the Al alloy is flowed and embedded in the second connection hole 17 (for example, Journal of Vacuum Science and Technology B8 (5) (1990) p. 1158-p.
Page 1160 (Journal of Vacuum Science and Technology B8
(5) (1990) pp.1158-1160)). In addition, (a) of FIG.
In (b), 12 is a first insulating film, 13 is a first connection port, and 14 and 15 are first wirings, respectively.

By using such a method, the step coverage of the second wiring 19 in the second connection hole 17 can be prevented from being lowered, so that disconnection failure due to electromigration or stress migration can be prevented.

[0007]

However, in the conventional structure as described above, when the Al alloy is heated by irradiating the laser beam L as shown in FIG.
Since the alloy also flows laterally, the second wirings 18, 19
There is a problem that a short circuit occurs between them and the yield of the semiconductor device is reduced.

The present invention solves the above problems, and in a semiconductor device, it is possible to prevent a wiring disconnection defect in a connection hole due to electromigration or stress migration without causing a short circuit between the wirings. Is intended to be manufactured.

[0009]

In order to solve the above problems, the first means of the present invention is to fill an insulating film between wirings, or to deposit an insulating film only on the sidewalls of wirings, or After depositing a conductive film having a melting point higher than that of the wiring material only on the side wall of the wiring, the wiring is heated by an energy beam or the like to flow and the wiring in the connection hole is buried.

A second means of the present invention is the same as the first means, wherein after filling the insulating film between the wirings, the natural oxide film on the surface of the wirings is removed in vacuum, and the wirings are vacuumed. Is to heat.

[0011]

By the first means, before heating the wirings, an insulating film is embedded between the wirings, or an insulating film is deposited only on the side walls of the wirings, or only the side wall of the wirings has a melting point higher than that of the wiring material. By depositing a high conductive film,
Since it is possible to prevent the wirings from flowing in the lateral direction, it is possible to prevent disconnection defects of the wirings in the connection holes due to electromigration or stress migration without causing a short circuit between the wirings.

Further, the flow of the wiring can be enhanced by the second means, and the wiring can be embedded more reliably.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 (a) to 1 (d) are sectional views showing respective steps of the method for manufacturing a semiconductor device according to the first embodiment of the present invention.

First, as shown in FIG. 1A, a first insulating film 21 is formed on a semiconductor substrate 20 on which a semiconductor element is formed, and a first connection hole 22 is formed in the first insulating film 21. Then, the first wirings 23 and 24 are formed on the first connection hole 22 and the first insulating film 21, respectively. In this state, the second insulating film 25 is deposited on the entire surface and flattened,
After forming the second connection hole 26 in the second insulating film 25, the second wirings 27 and 28 are formed, respectively.

In this case, as the first insulating film 21 and the second insulating film 25, a silicon oxide film containing B and P by atmospheric pressure CVD method, or plasma CVD, respectively.
A silicon oxide film by the method is used. In addition, the first wiring 2
A pure Al film or an Al alloy film is used as the wirings 3, 24 and the second wirings 27, 28. In addition, a laminated film structure of an Al alloy film and a conductive film, for example, Ti / Al-Si-Cu / T is used.
i laminated film structure, TiN / Al-Si-Cu / TiN / T
i laminated film structure, TiW / Al-Si-Cu / TiW / T
i laminated film structure, TiWN / Al-Si-Cu / TiWN
A / Ti laminated film structure may be used. In addition to these, other types of conductive films such as polycrystalline Si and amorphous S
You may use the laminated film structure which consists of i. Al in this case
Ti, TiN, TiW, TiW on top of the -Si-Cu film
N film, when heating the wiring by the energy beam,
Since it has the effect of increasing the absorption efficiency of the energy beam, even if the energy density of the beam is small, Al-Si-
The Cu film can be made to flow. In addition, Al-Si-
Instead of the Cu film, an Al alloy film containing an element other than Si or Cu as an impurity may be used.

Next, as shown in FIG. 1B, after depositing a third insulating film 29 on the entire surface, a resist film 30 is applied. In this case, as the third insulating film 29, a silicon oxide film formed by the plasma CVD method with good step coverage is used.

Next, as shown in FIG. 1C, the resist film 30 is exposed by dry etching to the surface of the third insulating film 29 above the second wirings 27 and 28. Etching is performed until after that, and then the etching back is performed under the condition that the etching rates of the third insulating film 29 and the resist film 30 are almost the same. Etchback is the second wiring 2
The second wiring 27,
The insulating film 29 is left between the layers 28.

Finally, as shown in FIG. 1D, the entire surface is irradiated with a laser beam L as an energy beam,
By heating the second wiring 28, the second connection hole 26
Embed by flowing into. The atmosphere for irradiating the laser beam L may be any kind of gas, and may be vacuum or air.

When such a method is used to irradiate the laser beam L to heat the second wirings 27 and 28,
Since the insulating film 29 embedded between the second wirings 27 and 28 prevents lateral flow of the second wirings 27 and 28,
A short circuit between the second wirings 27 and 28 does not occur. Further, since the second wirings 27 and 28 are heated after being processed and formed, there is no problem even if the morphology of the surface of the second wirings 27 and 28 is slightly deteriorated by the heating. This is because if the second wirings 27, 28 are heated before being processed and formed, the surface morphology of the second wirings 27, 28 deteriorates, so that the second wirings 27, 28 are subjected to a photolithography process.
This is because there arises a problem that it becomes difficult to form the resist pattern.

Before irradiation with the laser beam L, the second wiring 27 is formed by Ar sputter etching in vacuum.
A method may be used in which the natural oxide film on the upper part of 28 is removed and then the laser beam L is continuously irradiated without breaking the vacuum.

In addition, for heating the second wirings 27 and 28,
The following method may be used. That is, after the step shown in FIG. 1C, Ar sputter etching is performed in vacuum to remove the natural oxide film on the surface of the second wirings 27 and 28. This is the second wiring 27, 28
This is for making it easier to flow when heating. In the case of the laminated film structure, the conductive film on the second wirings 27 and 28 may be entirely removed by Ar sputter etching or may be left thin. Then, continuously in a second vacuum
By heating the wiring 28, the wiring 28 is flowed and embedded in the second connection hole 26. The heating of the wiring is, for example, 300 to
This is performed by placing the semiconductor substrate 20 in a holder set to a temperature of 600 ° C.

A second embodiment of the present invention will be described below with reference to the drawings. FIGS. 2A to 2D are sectional views showing respective steps of the method for manufacturing a semiconductor device according to the second embodiment of the present invention.

Since the process of this embodiment shown in FIG. 2A is the same as the process of the first embodiment shown in FIG. 1A, the same components are designated by the same reference numerals. And detailed description thereof will be omitted.

First, after the step shown in FIG. 2A,
As shown in FIG. 2B, the third insulating film 31 is deposited on the entire surface. In this case, as the third insulating film 31, a silicon oxide film by a plasma CVD method with good step coverage, such as an ozone TEOS oxide film, is used.

Next, as shown in FIG. 2C, the third insulating film 31 is removed by using a dry etching method, so that the third insulating film 31 is formed only on the side walls of the second wirings 27 and 28. Leave the membrane 31.

Finally, as shown in FIG. 2D, the entire surface is irradiated with the laser beam L, and the second wiring 28 is heated so that the second wiring 28 is fluidized and embedded.
If such a method is used, when the laser beam L is irradiated, the third insulating film 31 deposited on the sidewalls of the second wirings 27 and 28 prevents the second wirings 27 and 28 from flowing laterally. As a result, it is possible to prevent a disconnection defect of the second wiring 28 in the second connection hole 26 due to electromigration or stress migration without causing a short circuit between the second wirings 27 and 28. . Moreover, since the step of applying the resist film 30 in the first embodiment can be omitted, the number of steps can be reduced.

In this embodiment, the second wiring 2
Although the third insulating film 31 was deposited only on the side walls of 7, 28,
Instead of the insulating film, a conductive film having a melting point higher than that of the wiring material may be used. By using such a method, the wiring can be electrically and mechanically reinforced by forming the conductive film on the sidewall, so that the wiring having high reliability can be formed.

In the first and second embodiments, the second wirings 27 and 28 are made to flow by the laser beam L. However, instead of the laser beam L, another energy beam may be used. Good.

In this embodiment, the Al alloy film is used as the wiring material, but other kinds of conductive films may be used. Further, although the structure of the two-layer wiring is shown in the present embodiment, the same effect can be obtained in the one-layer wiring or the multilayer wiring structure of three or more layers.

[0030]

As described above, according to the present invention, the insulating film is formed between the wirings before heating the wirings, or the insulating film is deposited only on the side walls of the wirings, or the side wall of the wirings. Since a conductive film having a melting point higher than that of the wiring material is applied only to the wiring, the lateral flow of the wiring can be suppressed, so that it is possible to form a multilayer wiring having a high yield while preventing a short circuit between the wirings. Become. In addition, after the insulating film is embedded between the wirings, the flow of the wirings can be enhanced by removing the natural oxide film on the surface of the wirings in a vacuum.
Wiring can be embedded more reliably.

[Brief description of drawings]

1A to 1D are cross-sectional views of respective steps of a method for manufacturing a semiconductor device according to a first embodiment of the present invention.

2A to 2D are cross-sectional views of respective steps of a method for manufacturing a semiconductor device according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of steps in a conventional method of manufacturing a semiconductor device.

4A and 4B are cross-sectional views of respective steps of a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

 20 semiconductor substrate 25 second insulating film 26 second connection hole 27, 28 second wiring 29, 31 third insulating film 30 resist film

Claims (5)

[Claims] 1. A step of forming a connection hole in an insulating film deposited on a semiconductor substrate, a step of forming wirings on the insulating film and the connection hole, respectively, and between the wirings separately from the insulating film. A method of manufacturing a semiconductor device, comprising: a step of burying an insulating film; and a step of flowing at least wiring in the connection hole so as to flow and bury the wiring in the connection hole. 2. A step of forming a connection hole in an insulating film deposited on a semiconductor substrate, a step of forming wirings on the insulating film and the connection hole respectively, and at least on a sidewall of the wiring in the connection hole. A method of manufacturing a semiconductor device comprising: a step of depositing an insulating film separately from an insulating film; and a step of heating at least the wiring in the connection hole to cause the wiring in the connection hole to flow and be embedded. 3. A step of forming a connection hole in an insulating film deposited on a semiconductor substrate, a step of forming wiring on the insulating film and in the connection hole respectively, and at least on a sidewall of the wiring in the connection hole. A method of manufacturing a semiconductor device, comprising: a step of depositing a conductive film having a melting point higher than that of a wiring material; and a step of flowing at least the wiring in the connection hole to flow and bury the wiring in the connection hole. . 4. The method for manufacturing a semiconductor device according to claim 1, further comprising the step of heating the wiring with an energy beam. 5. The method according to claim 1, further comprising a step of removing a natural oxide film on a surface of the upper portion of the wiring in a vacuum after the insulating film is embedded between the wiring and a step of heating the wiring in a vacuum. 4. The method for manufacturing a semiconductor device according to any one of 3 above.