Methods for forming aluminum metal wirings

Details Methods for forming aluminum metal wirings Methods for forming aluminum metal wirings

2002-11-27

2004-01-06

Fourson, George (Department: 2823)

Semiconductor device manufacturing: process

Coating with electrically or thermally conductive material

To form ohmic contact to semiconductive material

C438S626000, C438S627000, C438S628000, C438S629000, C438S641000, C438S643000, C438S644000, C438S645000, C438S646000, C438S688000

Reexamination Certificate

active

06673718

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to the manufacture of semiconductor integrated circuit devices, and more particularly, the present invention relates to methods of forming metal wiring of semiconductor integrated circuit devices.
2. Description of the Related Art
The proper formation of metal wiring is an increasingly important aspect of the manufacture of semiconductor devices. The resistance of the metal wiring should as low as possible to allow for the rapid transmission of electrical signals. However, the circuit designer must balance low resistance against economic efficiencies and device reliability. In this regard, aluminum is generally regarded as a favorable material for achieving a reliable wiring of low resistance at relatively low cost, and accordingly, aluminum has been widely adopted in the formation of the metal wiring of semiconductor devices.
In the meantime, as the degree of integration of components of semiconductor devices continues to increase, the width and the thickness of the metal wiring have decreased. In addition, contact holes and recesses formed in the semiconductor substrate and insulating layers have become smaller and smaller, resulting in increased aspect ratios. The development of techniques for reliably and completely filling the holes having increased aspect ratios has thus become a significant factor in the ability to realize further increases in device integration.
Al-CVD (aluminum chemical vapor deposition) is a technique which is used to fill contact holes and recesses with a low resistance aluminum material. Al-CVD processes are classified into two types, i.e. blanket-Al deposition processes and selective-Al deposition processes. In blanket-Al deposition processes, aluminum is deposited on the entire surface of the wafer so as to fill the contact holes. This process relies in part on the favorable step coverage characteristics of aluminum. However, when the aluminum is deposited to certain thicknesses, wafer surface roughness can occur and the filling of a small contact holes is difficult due to the formation of voids within the holes.
On the other hand, selective-Al deposition processes selectively deposit aluminum by utilizing a difference in growth rate characteristics between growth on an insulating layer and growth on a conductive layer. This technique is generally unavailable, however, in the case where a blanket metal barrier layer is deposited before the deposition of aluminum to suppress the reaction of aluminum atoms of the aluminum with the silicon atoms of the underlying substrate. The presence of this blanket barrier metal layer prevents the selective formation of the metal interconnection only in the contact holes using the selective-Al deposition process.
A preferential metal deposition (PMD) method for forming metal interconnections in the presence of barrier metal layers is described in commonly assigned U.S. Pat. No. 6,376,355, issued Apr. 23, 2002, the contents of which are incorporated herein by reference.
Referring initially to FIG.
1
(
a
), one embodiment of the PMD process is partially characterized by the deposition of a TiN/Ti film
102
on an upper surface of a dielectric layer
100
, and on an interior surface of a contact hole
104
formed in the dielectric layer
100
. Reference number
102
a
denotes a Ti film, and reference number
102
b
denotes a TiN film. Then, still referring to FIG.
1
(
a
), a material layer
106
is formed over the upper surface only of the TiN/Ti film
102
. Examples of the material layer
106
include aluminum, titanium or tantalum. Then, the resultant structure having the material layer
106
is exposed to air or oxygen plasma, thereby at least partially oxidizing the material layer
160
to form an anti-nucleation layer (ANL)
108
as shown in FIG.
1
(
b
). Examples of the ANL
108
include aluminum oxide, titanium oxide or tantalum oxide.
Referring to FIG.
1
(
c
), the resultant structure having the ANL
108
is subjected to a blanket CVD of aluminum. However, aluminum is not CVD deposited over the upper surface of the dielectric layer
100
due to the presence of the ANL
108
. Rather, an aluminum layer
110
is selectively formed only on the interior surface of the contact hole
104
.
Then, as shown in FIG.
1
(
d
), physical vapor deposition (PVD) of aluminum is carried out, followed by a reflow process, to completely fill of the contact holes in the dielectric layer with aluminum
112
.
Use of the PMD process allows for the filling of contact holes having large aspect ratios with aluminum by utilizing the favorable step coverage characteristic of the CVD-Al. One drawback with the PMD process, however, resides in the reduced throughput primarily resulting from formation of an insulating layer as the ANL
108
. For example, the deposition of the material layer
106
constitutes an additional process step. Further, a vacuum break is typically made to occur for the purpose of naturally oxidizing the metal layer
106
, which also increases processing time.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention, an aluminum wiring is selectively formed within a contact hole or groove of a substrate. An intermediate layer which includes nitrogen is formed over the main surface of a substrate and over the interior surface of the contact hole or groove. A first surface portion of the intermediate layer which is located over the main surface of the substrate is treated with a plasma to form a passivity layer at the first surface portion of the intermediate layer. Then, without an intervening vacuum break, an aluminum film is CVD deposited only over a second surface portion of the intermediate layer which is located over the interior surface of the contact hole or recess. The plasma treatment of the first surface portion of the intermediate layer prevents the CVD deposition of the aluminum film over the first surface portion of the intermediate layer.
According to another aspect of the present invention, an aluminum wiring is selectively formed within a contact hole or groove of a substrate. An intermediate layer which includes nitrogen is formed over the main surface of a substrate and over the interior surface of the contact hole or groove. A first surface portion of the intermediate layer which is located over the main surface of the substrate is treated with a plasma to form a passivity layer at the first surface portion of the intermediate layer. Then, without an intervening vacuum break, an aluminum film is CVD deposited only over a second surface portion of the intermediate layer which is located over the interior surface of the contact hole or recess. The plasma treatment of the first surface portion of the intermediate layer prevents the CVD deposition of the aluminum film over the first surface portion of the intermediate layer. Then, still without an intervening vacuum break, an aluminum layer over the passivity layer and over the aluminum film so as to fill the contact hole or groove.
According to still another aspect of the present invention, an aluminum wiring is selectively formed within a contact hole or groove of a substrate. A first intermediate layer is formed over the main surface of a substrate and over the interior surface of the contact hole or groove. Then, a second intermediate layer which includes nitrogen is formed over the first intermediate layer. A first surface portion of the second intermediate layer which is located over the main surface of the substrate is treated with a plasma to form a passivity layer at the first surface portion of the intermediate layer. Then, without an intervening vacuum break, an aluminum film is CVD deposited only over a second surface portion of the second intermediate layer which is located over the interior surface of the contact hole or recess. The plasma treatment of the first surface portion of the second intermediate layer prevents the CVD deposition of the aluminum film over the first surface portion of the second intermediate layer

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