Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
2002-07-03
2004-08-17
Smith, Matthew (Department: 2825)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S653000, C438S927000, C257S767000, C257S751000, C257S486000
Reexamination Certificate
active
06777328
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device and a method of manufacturing the same, and particularly to a method of forming a multilayered conductive layer for a semiconductor device, which improves electromigration resistance.
A conventional multilayered conductive layer configuration employed in a semiconductor device is generally illustrated as a sectional structure shown in FIG.
6
. An aluminum (Al) film
14
as a conductive layer is used, and a titanium (Ti) film
12
and a titanium nitride (TiN) film
13
provided on the Ti film
12
are used as a barrier layer
16
on an insulator layer
11
deposited on an integrated circuit
10
, so as to avoid a conductive layer-to-layer leak developed by diffusion of Al thereof into an insulating film. Now, the Ti film is effective in improving the quality of an Al film, principally, its orientation, and an improvement in the orientation of the Al film provides the effect of enhancing electromigration resistance. This electromigration (EM) is a phenomenon in which atoms are moved by the flow of a current. Since it produces a failure such as breaking of a conductive layer, an improvement in EM resistance is essential to the enhancement of reliability. Further, the TiN film
13
is needed to prevent the reaction of the Ti film and the Al film for the wired metal.
Next, the Al film
14
used as the wired metal is deposited by heating at 200° C. to 400° C. The reason why heating is made upon the formation of the Al film, is to make an Al grain large by heating to enhance the EM resistance and to improve step coverage (state of a film deposited on a step) in a contact hole. The migration has been considered to take place along a grain boundary. Since the grain boundary is reduced if the Al grain is relatively set larger than a conductive layer width, the electromigration (EM) can be restrained.
Thereafter, Ti, TiN, or a laminated layer of Ti and TiN, for example is deposited as an antireflection film (ARM)
15
relative to an Al surface based on a photolithography process. Further, the so-deposited film is subjected to a photolithography process and an etching process and then to patterning, whereby each of conductive layers is formed.
In the above method on the other hand, since the Al film
14
is deposited at the high temperature of from 200° C. to 400° C. upon deposition thereof after the formation of the TiN film
13
, nitrogen gas (N
2
gas) is released from the surface of the TiN film
13
and from within the TiN film
13
to within an Al deposition chamber, so that N
2
is brought into the Al film
14
. It has generally been known that the mixing of N
2
gas upon Al deposition interferes with the growth of a grain and hence EM resistance is degraded. Thus, the present method had a problem that reliability was degraded.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above problem involved in the conventional semiconductor device and semiconductor device manufacturing method, particularly, the method of forming the multilayered conductive layer for the semiconductor device. It is an object of the present invention to provide a novel and improved semiconductor device and a method of manufacturing the semiconductor device, which are capable of preventing N
2
from being captured during the deposition of a conductive layer Al film and enhancing electromigration resistance.
The present invention provides a method of manufacturing a semiconductor device, comprising, forming an insulator layer on an integrated circuit, forming a barrier layer comprised of a first titanium film and a titanium nitride film on the insulator layer, heat-treating the barrier layer to release nitrogen gas from the titanium nitride film, forming a second titanium film on the barrier layer, and forming an aluminum film used as a wired metal on the second titanium film.
REFERENCES:
patent: 4427461 (1984-01-01), Kindlimann
patent: 5242860 (1993-09-01), Nulman et al.
patent: 5459353 (1995-10-01), Kanazawa
patent: 5847459 (1998-12-01), Taniguchi
patent: 5972179 (1999-10-01), Chittipeddi et al.
patent: 6080665 (2000-06-01), Chen et al.
Calvin Lee
Oki Electric Industry Co. Ltd.
Smith Matthew
Volentine & Francos, PLLC
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