JPH0567611A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To align a photomask without flattening an alignment mask region by a method wherein the auxiliary metal film of the alignment mask region is removed by etching when the recesses and protrusions of a wiring layer region in a multilayer interconnection structure are flattened. CONSTITUTION:First, the conductive film 10 for the n-th wiring layer is patterned, a layer insulating film 12 is formed thereon, a contact hole is formed on a wiring layer region by patterning, an alignment mark is formed on an alignment mark region, and a Ti layer 14 is formed on the whole surface. Then, the Ti layer of the alignment mark region is etched using the patterned resist 16 as a mask. Subsequently, the resist 16 is exfoliated, and the conductive film 18 for the (n+1)th wiring layer is formed on the whole surface. At this time, as rugged shape of the alignment mark is maintained, the resist can be patterned accurately when the (n+1)th patterning is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having a multi-layered wiring layer, and more particularly to a semiconductor device using an Al alloy as a conductive film for a wiring layer and a method for manufacturing the same. In recent years, with the miniaturization and high integration of semiconductor integrated circuits, a technique for growing a conductive film so as to fill fine through holes (contact holes) is required. As one of the techniques, a technique for forming a conductive film by using a high temperature bias sputtering method using an Al alloy as a material has been developed.

[0002]

2. Description of the Related Art A conventional method of manufacturing a semiconductor device will be described with reference to FIG. First, by the high temperature bias sputtering method,
The n-th wiring layer conductive film 10 made of an Al alloy is formed, and the n-th wiring layer conductive film 10 is patterned using a photolithography technique. Subsequently, an interlayer insulating film 12 is formed on the n-th conductive film for wiring layer 10,
The interlayer insulating film 12 is patterned by using a photolithography technique to form a contact hole in the wiring layer area and an alignment mark in the alignment mark area. Then, the Ti layer 1 is formed on the entire surface of the interlayer insulating film 12.
4 is formed (FIG. 4A). This Ti layer 14 is the nth
When the + 1st wiring layer conductive film 18 is formed, Al
It has a function of reducing the surface expansion force of the alloy to promote fluidity and flattening the unevenness of the interlayer insulating film 12.

Next, a conductive layer 18 for the (n + 1) th wiring layer made of an Al alloy is formed on the Ti layer 14 by a high temperature bias sputtering method (FIG. 4B). Al alloy is T
Since it is formed on the i layer 14, the Al alloy flows into the contact hole of the interlayer insulating film 12, and the surface of the (n + 1) th conductive film for wiring layer 18 can be flattened. But,
At this time, the unevenness of the alignment mark is also flattened.

Next, the conductive film 18 for the (n + 1) th wiring layer
A resist 20 is applied to pattern (FIG. 4C). Subsequently, even if an attempt is made to pattern the resist 20 by using the photolithography technique,
Since the unevenness of the alignment mark is also flattened by the (n + 1) th wiring layer conductive film 18, the alignment mark cannot be detected.

[0005]

As described above, in the conventional method of manufacturing a semiconductor device, the (n + 1) th conductive film 18 for wiring layer is formed on the nth conductive film 10 for wiring layer. First, the auxiliary metal film 14 is formed in order to planarize the surface of the (n + 1) th conductive film 18 for wiring layer. However, since the auxiliary metal film 14 flattens the unevenness of the wiring layer region of the n-th wiring conductive film 18, the unevenness of the alignment mark region is also flattened, so that the alignment of the photomask can be performed. There was a problem that I could not do it.

An object of the present invention is to align the photomask without flattening the unevenness in the alignment mark area when flattening the unevenness in the wiring layer area with the Al alloy for the wiring layer. A semiconductor device and a manufacturing method thereof are provided.

[0007]

The above object is to form a first wiring layer conductive film, an interlayer insulating film formed on the first wiring layer conductive film, and an interlayer insulating film formed on the interlayer insulating film. An auxiliary metal film for promoting fluidity of the Al alloy formed in the upper layer, and a second conductive film for wiring layer made of the Al alloy formed on the auxiliary metal film and having a flat surface. In the semiconductor device having, the auxiliary metal film is not formed in the alignment mark region in which the alignment mark having the uneven shape for aligning the photomask is formed,
This is achieved by a semiconductor device characterized in that the unevenness shape of the alignment mark is maintained without flattening the surface of the second conductive film for wiring layer.

[0008] The above object is to perform a first step of forming a first wiring layer conductive film, a second step of forming an interlayer insulating film on the first wiring layer conductive film, and the interlayer insulating film. A on the membrane
a third step of forming an auxiliary metal film for promoting fluidity of the 1-alloy, and a fourth step of forming a second conductive layer for wiring layer made of an Al alloy on the auxiliary metal film. In the method for manufacturing a semiconductor device, after the third step,
A step of etching away the auxiliary metal film in the alignment mark area in which the concave-convex alignment mark for aligning the photomask is formed is provided, and in the fourth step, the step of forming the auxiliary mark in the alignment mark area is performed. Two
The method of manufacturing a semiconductor device is characterized in that the uneven shape of the alignment mark is maintained without flattening the surface of the conductive film for wiring layer.

[0009]

According to the present invention, since the alignment mark is not buried by the Al alloy, the alignment can be performed even after the conductive film for the wiring layer is formed, and the accurate alignment can be performed. ..

[0010]

EXAMPLE A semiconductor device according to an example of the present invention will be described with reference to FIG. FIG. 1 shows the structures of the nth wiring layer and the (n + 1) th wiring layer. The nth wiring layer conductive layer 10 is patterned, and the nth wiring layer conductive layer 10 is patterned.
An interlayer insulating film 12 is formed on the second conductive layer 10 for wiring layer. A contact hole is formed in the wiring layer region of the interlayer insulating film 12, and an uneven alignment mark is formed in the alignment mark region.

On the wiring layer region of the interlayer insulating film 12, the nth layer is formed.
The Ti layer 14 for promoting the fluidity of the Al alloy used for the + 1st wiring layer conductive film 18 is formed, but T is formed on the alignment mark region of the interlayer insulating film 12.
The i layer 14 is not formed. Although the n + 1-th conductive film 18 for wiring layer is formed on the Ti layer 14,
The (n + 1) th conductive film for wiring layer 18 in the wiring layer region is made of Al.
Since the Ti layer 14 for promoting the fluidity of the alloy is formed, the surface is flattened. On the other hand, since the Ti layer 14 for promoting the fluidity of the Al alloy is not formed on the (n + 1) th conductive film 18 for the wiring layer in the alignment mark region, the surface is not flattened and the position in the interlayer insulating film 12 is increased. The concave and convex shape of the alignment mark is maintained.

As described above, according to this embodiment, the uneven shape of the alignment mark is maintained on the surface of the conductive film for the upper wiring layer. Even in the patterning of the conductive film for the upper wiring layer, accurate alignment can be performed by using the alignment mark. A method of manufacturing a semiconductor device according to an embodiment of the present invention will be described with reference to FIGS.

First, the nth wiring layer conductive film 10 made of an Al alloy is formed by sputtering or vapor deposition, and the nth wiring layer conductive film 10 is patterned using a photolithography technique. In addition, here, the conductive film 1
0 was formed by the high temperature bias sputtering method. Then, the interlayer insulating film 12 is formed on the n-th conductive film 10 for wiring layer.
Then, the interlayer insulating film 12 is patterned using a photolithography technique to form a contact hole in the wiring layer region and an alignment mark in the alignment mark region. Then, a Ti layer 14 is formed on the entire surface of the interlayer insulating film 12 (FIG. 2A). This Ti layer 1
4 has a function of reducing the surface expansion force of the Al alloy to promote fluidity and flatten the irregularities of the interlayer insulating film 12 when forming the (n + 1) th conductive film 18 for wiring layer.

Next, a resist 16 is applied on the entire surface and patterned so that the alignment mark area is opened.
Then, the Ti layer 14 in the alignment mark region is etched by using the patterned resist 16 as a mask (FIG. 2B). As the etching solution for the Ti layer 14, any material such as Freon-based, Freon-based, or HF-based can be used as long as it can etch Ti.

Next, the resist 16 is peeled off, and the entire surface is formed by the high temperature bias sputtering method with the (n + 1) th Al alloy alloy.
A th conductive film 18 for wiring layer is formed (FIG. 2C).
At this time, the wiring layer region in which the Ti layer 14 is formed is A
Since the l-alloy has a high fluidity, it can be applied to the n +
The surface of the first conductive film 18 for wiring layer is flattened,
In the alignment mark region where the Ti layer 14 is not formed, the surface is not flattened due to the surface force of the Al alloy, and the uneven shape of the alignment mark is maintained.

Next, the conductive film 18 for the (n + 1) th wiring layer
A resist 20 is applied to pattern (FIG. 3A). Subsequently, the resist 20 is patterned by using a photolithography technique. Since the surface of the Al alloy in the alignment mark region is not flattened and the unevenness of the alignment mark is maintained, the resist 20 is not formed.
It is possible to accurately pattern.

Next, the patterned conductive film 20 is used as a mask to etch the (n + 1) th conductive film 18 for wiring layer, and the resist 20 is peeled off to complete the process (FIG. 3B). As described above, according to this embodiment, the uneven shape of the alignment mark is maintained on the surface of the upper conductive film for the wiring layer. Even in the patterning of the conductive film for the upper wiring layer, accurate alignment can be performed by using the alignment mark.

The present invention is not limited to the above-mentioned embodiment, but there are various modifications. For example, although Ti is used for the auxiliary metal film for promoting the fluidity of the Al alloy in the above-mentioned embodiment, a metal other than Ti may be used as long as it has a high surface energy or a melting point higher than that of the Al alloy.

[0019]

As described above, according to the present invention, when the wiring layer conductive film made of an Al alloy is formed, when the unevenness of the wiring layer region is flattened by the wiring layer Al alloy, the alignment is performed. Since the unevenness in the mark region is not flattened, the alignment can be performed even after the formation of the conductive film for the wiring layer, and the accurate alignment can be performed.

[Brief description of drawings]

FIG. 1 is a diagram showing a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a process diagram (1) showing a method for manufacturing a semiconductor device according to an embodiment of the present invention.

FIG. 3 is a process diagram (2) showing the method for manufacturing the semiconductor device according to the embodiment of the present invention.

FIG. 4 is a process chart showing a method of manufacturing a semiconductor device according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Conductive film for wiring layers of the n-th 12 ... Interlayer insulating film 14 ... Ti layer 16 ... Resist 18 ... Conductive film for wiring layers of the (n + 1) th wiring layer 20 ... Resist

Claims (4)

[Claims] 1. A first wiring layer conductive film, an interlayer insulating film formed on the first wiring layer conductive film, and an Al alloy formed on the interlayer insulating film and formed in an upper layer. In a semiconductor device having an auxiliary metal film for promoting the fluidity of the second wiring layer and a second conductive film for wiring layer made of an Al alloy formed on the auxiliary metal film and having a flattened surface. The auxiliary metal film is not formed in the alignment mark region where the uneven alignment mark for alignment is formed, and the surface of the conductive film for the second wiring layer is flattened. The semiconductor device is characterized in that the concave and convex shape of the alignment mark is maintained. 2. The semiconductor device according to claim 1, wherein the auxiliary metal film is a Ti film. 3. A first step of forming a conductive film for a first wiring layer, a second step of forming an interlayer insulating film on the conductive film for a first wiring layer, and a step of forming an interlayer insulating film on the interlayer insulating film. A third step of forming an auxiliary metal film for promoting the fluidity of the Al alloy, and a fourth step of forming a second conductive layer for the wiring layer made of the Al alloy on the auxiliary metal film. In the method for manufacturing a semiconductor device having the above, after the third step, a step of etching away the auxiliary metal film in an alignment mark region in which an uneven alignment mark for aligning a photomask is formed is provided. In the fourth step, the unevenness of the alignment mark is maintained without flattening the surface of the conductive film for the second wiring layer in the alignment mark region. Manufacturing method. 4. The method of manufacturing a semiconductor device according to claim 3, wherein the auxiliary metal film is a Ti film.