Metal interconnection structure of semiconductor device

Details Metal interconnection structure of semiconductor device Metal interconnection structure of semiconductor device

1998-06-25

2001-01-02

Hardy, David (Department: 2815)

Active solid-state devices (e.g., transistors, solid-state diode

Combined with electrical contact or lead

Of specified material other than unalloyed aluminum

C257S750000, C257S755000

Utility Patent

active

06169327

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a metal interconnection structure of a semiconductor device, and more particularly to a metal interconnection structure of a semiconductor device having a novel ARC layer being capable of preventing reflection of a metal interconnection and improving a step coverage thereof.
2. Description of the Related Art
In general, an aluminum is widely used as the material for a metal interconnection because of its low resistivity. However, when the aluminum is patterned by photolithography, an interconnection badness occurs by a notching due to the high surface reflectivity of the aluminum. To solve this problem, the aluminum is patterned by photolithography, after an anti-reflective coating (ARC) layer is formed thereon, thereby preventing the surface reflectivity of the aluminum. The ARC layer is made of a TiN.
FIG. 1
shows a conventional metal interconnection structure wherein an ARC layer is formed on an aluminum layer. With reference to
FIG. 1
, an insulating layer
12
is formed on a semiconductor substrate
10
on which a conductive layer pattern
11
is formed. The insulating layer
12
has a contact hole
13
exposing a portion of the conductive layer pattern
11
. On the surface of the contact hole
13
and the insulating layer
12
, is formed a barrier metal layer
14
. An aluminum layer
15
is formed on the barrier metal layer
14
as an interconnection material. An ARC layer is formed on the aluminum layer
15
for preventing reflection of the aluminum layer
15
. Preferably, the ARC layer is made of a TiN layer
16
. The TiN layer
16
is a PVD-TiN layer formed by a Physical Vapor Deposition (PVD).
However, this conventional interconnection structure above described has the following problems due to a grain boundary of the aluminum layer
15
.
FIG. 2
is an enlarged view of “A” portion in FIG.
1
. Referring to
FIG. 2
, a fine void B exists between grains of the aluminum layer
15
since the grain boundary of the aluminum layer
15
is not uniform. As a result, portions of the TiN layer
16
are thinly formed on the aluminum layer
15
. Furthermore, a crack occurs at the TiN layer
16
, whereby a step coverage of a metal interconnection becomes poor. Moreover, since residues of photoresist and chemical materials remain in the void after performing the photolithography, defects occur in the metal interconnection. For the purpose of preventing the defects, a method by which the TiN layer
16
is thickly formed, is proposed. However, a bridge occurs between interconnections due to the thick TiN layer
16
.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a metal interconnection structure of a semiconductor device having a novel ARC layer being capable of preventing reflection of an interconnection metal and improving a step coverage thereof for solving the problems in the conventional art.
To accomplish this above object, a metal interconnection structure of a semiconductor device according to the present invention includes a metal layer having a high surface reflectivity and an ARC layer formed on the metal layer. The ARC layer has a first layer formed on the metal layer and a second layer formed on the first layer. The first layer has a good step coverage property, and the second layer has a low surface reflectivity.
Preferably, the first layer, is a polysilicon layer and the second layer is a CVD-TiN layer. The polysilicon layer is formed to the thickness of 50 to 300 Å, and the CVD-TiN layer is formed to the thickness of 100 to 300 Å. Furthermore, the metal layer is made of one material selected from the group consisting of aluminum, aluminum alloy, tungsten, and copper. Preferably, the metal layer is an aluminum layer.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.


REFERENCES:
patent: 5032233 (1991-07-01), Yu et al.
patent: 5798568 (1998-08-01), Abercrombie et al.
patent: 5950107 (1999-09-01), Huff et al.
patent: 6005277 (1999-12-01), Liu et al.

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