JPH05102316A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form fine metal wiring wherein the flatness of its surface is not damaged or the resistance of its surface does not become high and the reliability formation method of the fine metal wiring. CONSTITUTION:A first metal film 5 is formed, by a sputtering method, on an insulating film 4 in which a connecting hole 4a has been formed on a semiconductor substrate 1 or lower-layer wiring 3A; it is irradiated with a laser beam; it is heated and melted; the connecting hole 4a is filled with a metal; the first metal film is etched and removed; and the metal with which the connecting hole 4a has been filled is left as a plug 5A. Then, a second metal film 6 is formed on the insulating film 4 and on the plug 5A; it is patterned; and upper-layer wiring 6A is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of manufacturing a semiconductor device,
In particular, it relates to a method for forming fine metal wiring. In recent years, semiconductor devices are being miniaturized in response to the demand for high integration and high density. For this reason, the dimensions of connection holes (contact holes, via holes) between wirings / elements and between layers are extremely small. It's getting smaller. If the contact hole is extremely small, the adhesion of the metal to the sidewall of the contact hole is insufficient when the metal film for wiring (mainly aluminum film) is formed by the sputtering method, and the reliability of the contact deteriorates. There is a problem such that a recess is formed and an insulating film (passivation film or the like) formed on the wiring is adversely affected. Therefore, it is desired that the connection hole of the fine metal wiring be completely filled with metal and that the wiring surface be flat.

[0002]

2. Description of the Related Art Two conventional examples of methods for forming fine metal wiring will be described. In both cases, the connection hole is filled with metal and the wiring surface is made flat.

First Example: First, aluminum (or aluminum alloy) is deposited on an insulating film having connection holes by a sputtering method to form an aluminum film for wiring. At this time, as described above, a deep recess is formed in the aluminum film in the connection hole. Next, the aluminum film is irradiated with a beam of excimer laser light to melt the aluminum.
As a result, the deep recesses of the aluminum film are filled with molten aluminum and the surface becomes flat. After the aluminum is solidified, the aluminum film is patterned by a lithography method to obtain a desired wiring. This method is disclosed in Japanese Patent Laid-Open No. 63-088443.

Second Example: This is a method applied to the formation of upper layer wiring in a multilayer wiring structure. First, deposit a relatively large amount of an aluminum alloy containing Si, Ge, Cu, etc. by a high temperature sputtering method on the surface of an insulating film having a connection hole on a lower layer wiring made of aluminum or an aluminum alloy containing a small amount of Si, etc. Then, an aluminum alloy film for the upper wiring is formed. At this time, by setting the substrate heating temperature near the melting point of the aluminum alloy, the lower layer wiring does not melt and the deposited aluminum alloy maintains the molten state, so that the inside of the connection hole is filled with aluminum and the aluminum alloy film Has a flat surface. After the aluminum alloy is solidified, the aluminum alloy film is patterned by a lithography method to obtain a desired wiring. This method is proposed by the present inventor.

[0005]

However, in the method of the first example, the irradiation area of the laser beam is small (for example, 9 mm ² ).
Therefore, the entire surface of the substrate cannot be irradiated at one time, so the aluminum film is sequentially melted by the stitching exposure method, but the aluminum film rises up to about 1 μm at the edge part of the laser beam to be irradiated, and the flatness of the wiring obtained by patterning this aluminum film There was a problem of impairing sex.

On the other hand, in the method of the second example, an alloy obtained by adding a relatively large amount of Si or Ge, Cu or the like to aluminum is used as a material for the upper layer wiring, but aluminum is added by adding a large amount of these elements. There are problems that the melting point is further lowered and the specific resistance is significantly increased (for example, when 10 atomic% of Si is added, it becomes about three times as high as that of pure aluminum) and the operation speed of the semiconductor device is lowered.

The present invention solves such a problem and can form fine metal wiring having high reliability of contact in a connection hole without impairing surface flatness or increasing resistance. It is an object of the present invention to provide a possible method of manufacturing a semiconductor device.

[0008]

To this end, [1] a first metal film 5 is formed by depositing a metal on an insulating film 4 having a connection hole 4a formed on a semiconductor substrate 1 or a lower wiring 3A. Process and the first metal film 5 is heated and melted by laser light irradiation to form the connection hole 4a.
With a metal, a step of removing the first metal film 5 by etching to leave the metal filled in the connection hole 4a as a plug 5A, and a metal is deposited on the insulating film 4 and the plug 5A. By providing a method of manufacturing a semiconductor device, which has a step of forming the second metal film 6 and a step of patterning the second metal film 6 to form the upper wiring 6A in this order, [2 ] In the insulating film 4 in which the connection hole 4a is provided on the lower layer wiring 3A,
A metal having a lower melting point than the material of the lower layer wiring 3A is deposited in a molten state by a high temperature sputtering method at a temperature lower than the melting point of the material of the lower layer wiring 3A to form the first metal film 15 and the connection hole 4a is filled with the metal. And a step of removing the first metal film 15 by an etching method and filling the metal filling the connection hole 4a with the plug 15
A step of leaving as A, a step of forming a second metal film 6 by depositing a metal having a lower specific resistance than the material of the first metal film 15 on the insulating film 4 and the plug 15A, and a second metal film. By providing a step of patterning 6 to form the upper wiring 6A in this order,
[3] A step of forming a first metal film 15 by depositing a metal having a melting point lower than that of the material of the lower layer wiring 3A on the insulating film 4 having the connection holes 4a formed on the lower layer wiring 3A; A step of melting the first metal film 15 by heating the film 15 together with the lower layer wiring 3A at a temperature lower than the melting point of the material of the lower layer wiring 3A to fill the connection hole 4a with metal; The step of leaving the metal removed by the etching method and filling the connection hole 4a as the plug 15A, and depositing a metal having a lower specific resistance than the material of the first metal film 15 on the insulating film 4 and the plug 15A And a step of forming the upper wiring 6A by patterning the second metal film 6 in this order. [2], [3]
In the above, it is achieved by using a material having a lower specific resistance than the material of the first metal film 15 as the second metal film 6.

[0009]

As described above, in the above-mentioned first and second conventional examples, there is a problem in the metal film formed for the upper layer wiring (also serving as the filling of the connection hole). Therefore, in the present invention, the metal film for upper layer wiring in the conventional example is limited to the purpose of filling the connection hole, and after the connection hole is filled, the metal film for the upper layer wiring is removed again except inside the connection hole. To form.

As a result, regardless of whether the metal film formed first has irregularities or a material having a high specific resistance is used, it has no relation to the upper wiring formed later.
Since the connection hole is filled at the time of forming the metal film for the upper layer wiring, a flat film is formed by the usual sputtering method. Therefore, there is no need for laser irradiation, and
It is not necessary to use a metal having a high specific resistance to lower the melting point. Flat wiring can be formed by using aluminum having a low specific resistance.

If the material of the first metal film has a high specific resistance, the inside of the connection hole will be filled with a metal having a high specific resistance. The effect on the characteristics can be ignored.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for forming fine metal wiring according to the present invention will be described with reference to FIGS. FIG. 1 is a sectional view showing a first embodiment of the present invention, and FIG. 2 is a sectional view showing a second embodiment of the present invention. (A) → (f), (a)
→ (e) shows the process sequence. In addition, in FIG.
The same parts as those in FIG. 1 are designated by the same reference numerals.

First Example: In FIG. 1 (a), 1 is a semiconductor substrate, 2 is a thickness of about 1 μm obtained by thermally oxidizing the semiconductor substrate 1.
Insulating film (SiO ₂ ), 3A is a lower layer wiring made of aluminum having a thickness of about 0.6 μm, and 4 is a thickness of about 0.7 obtained by the CVD method.
An insulating film made of PSG or the like having a thickness of 4 μm is a connection hole (via hole) having a diameter of about 0.6 μm obtained by patterning the insulating film 4 by a lithography method.

From this state, first, aluminum is deposited on the insulating film 4 (including the connection hole 4a) by a sputtering method to form a first metal film 5 having a thickness of about 0.6 μm. At this time, an aluminum film is also formed on the side wall and the bottom of the connection hole 4a, but the film thickness is thin, so that a deep recess is formed in the first metal film 5. This state is shown in Figure (b).

Next, a beam of XeCl excimer laser light (beam size: 2.3 × 2.3 mm, intensity density: 3.0 J / cm ²⁾ was formed on the surface of the first metal film 5 in a vacuum of about 10 ^-4 torr. ) Is irradiated to melt it. As a result, the inside of the connection hole 4a is filled with aluminum, the deep recess disappears, and the surface of the first metal film 5 immediately above the connection hole 4a becomes substantially flat. This state is the same figure
(c). However, at the edge portion of the irradiation field of the laser beam, swelling (height is about 1 μm) is generated on the surface of the first metal film 5, and it cannot be said that the surface is flat as a whole.

Next, the first metal film 5 is removed by etching (wet, but may be dry). However,
The aluminum filling the inside of the connection hole 4a is left as the plug 5A. This state is shown in FIG.

After that, aluminum is again deposited on the insulating film 4 and the plug 5A by a sputtering method to form a second metal film 6 having a thickness of about 0.6 μm. This state is the same figure
(e). Further, the second metal film 6 is patterned by a lithography method to obtain a desired upper layer wiring 6A. The upper layer wiring 6A has a flat surface, and is connected to the lower layer wiring 3A via the plug 5A. This state is shown in Figure (f).

Second Example: Since FIG. 2 (a) is the same as FIG. 1 (a), its explanation is omitted. From this state, first, the insulating film 4
An aluminum alloy containing Si in an amount of about 10 atomic% (melting point is 580 ° C.) is deposited on (including the contact hole 4a) by a sputtering method to form a first metal film 15 having a thickness of about 1.0 μm. At this time, the substrate is heated to 580 ° C. As a result, the lower layer wiring 3A does not melt (the melting point of Si is 660 ° C.), but since the first metal film 15 is deposited in a molten state, the inside of the connection hole 4a is filled with the aluminum alloy and the first metal film 15 is formed. The surface becomes substantially flat. This state is shown in Figure (b).

Next, the first metal film 15 is removed by etching (wet, but may be dry). However,
The aluminum alloy filling the inside of the connection hole 4a is plug 15
Leave as A. This state is shown in FIG.

After that, aluminum is deposited on the insulating film 4 and the plug 15A by a sputtering method to form a second metal film 6 having a thickness of about 0.6 μm. This state is the same figure
(d). Further, the second metal film 6 is patterned by a lithography method to obtain a desired upper layer wiring 6A. The upper layer wiring 6A is connected to the lower layer wiring 3A via the plug 15A. This state is shown in Figure (e).

Other Examples: The present invention is not limited to the above embodiments and can be carried out in various modified forms. For example, the material of the lower layer wiring 3A, the first metal film 5 or 15, and the second metal film 6 in the first and second examples may be an aluminum alloy (for example, 1% Si) to which a trace amount of element is added. ,
The present invention is also effective when the material of the first metal film 15 in the second example is an aluminum alloy to which an element other than Si, such as Ge or Cu, is added. Further, it can be applied to metal wirings other than aluminum type.

Further, the connection hole in the first example has the semiconductor substrate 1
The present invention is effective even in the case of a contact hole that connects the active region of 3 to the wiring 3A. Furthermore, in the second example, after the first metal film 15 is formed by a normal sputtering method, the entire substrate may be heated to 580 ° C. to flatten the surface of the first metal film 15.

[0023]

As described above, according to the method of manufacturing a semiconductor device of the present invention, the metal deposited on the insulating film is used to fill the connection holes formed in the insulating film, and then the metal on the insulating film is removed. Since the desired wiring is formed from the metal that has been removed and redeposited once again, a fine metal wiring with high reliability of contact in the connection hole is formed without impairing the flatness of the surface or increasing the resistance. It is possible to improve the reliability of the semiconductor device having a fine structure.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

[Explanation of symbols]

 1 Semiconductor Substrate 2 Insulating Film 3A Lower Layer Wiring 4 Insulating Film 4a Connection Hole 5, 15 First Metal Film 5A, 15A Plug 6 Second Metal Film 6A Upper Layer Wiring

Claims (4)

[Claims] 1. A step of forming a first metal film (5) by depositing a metal on a semiconductor substrate (1) or an insulating film (4) having a connection hole (4a) formed on a lower wiring (3A). A step of irradiating the first metal film (5) with a laser beam to melt it and fill the connection hole (4a) with a metal; and etching the first metal film (5) by an etching method. A step of removing and leaving the metal filling the connection hole (4a) as a plug (5A); and depositing a metal on the insulating film (4) and the plug (5A) to form a second metal film (6). ), And a step of patterning the second metal film (6) to form an upper wiring (6A) in this order. 2. A metal having a lower melting point than that of the material of the lower layer wiring (3A) is applied to the insulating film (4) having the connection hole (4a) formed on the lower layer wiring (3A). A step of forming the first metal film (15) by depositing it in a molten state by a high temperature sputtering method at a temperature lower than the melting point of and simultaneously filling the connection hole (4a) with metal; A step of removing (15) by an etching method to leave the metal filling the connection hole (4a) as a plug (15A); and depositing a metal on the insulating film (4) and the plug (15A). Manufacturing of a semiconductor device characterized by having a step of forming a second metal film (6) and a step of patterning the second metal film (6) to form an upper wiring (6A) in this order. Method. 3. A first metal film in which a metal having a melting point lower than that of the material of the lower layer wiring (3A) is adhered to an insulating film (4) having a connection hole (4a) formed on the lower layer wiring (3A). Forming the first metal film (15), and heating the first metal film (15) together with the material of the lower layer wiring (3A) at a temperature lower than the melting point of the lower layer wiring (3A). A step of melting (15) to fill the connection hole (4a) with a metal, and removing the first metal film (15) by an etching method to plug the metal filling the connection hole (4a) into a plug ( 15A), a step of depositing a metal on the insulating film (4) and the plug (15A) to form a second metal film (6), and the second metal film (6) And a step of forming an upper layer wiring (6A) by patterning the same in this order. 4. The semiconductor according to claim 2, wherein a metal having a lower specific resistance than the material of the first metal film (15) is used as a material of the second metal film (6). Device manufacturing method.