Method for forming a T-shaped plug having increased contact...

Details Method for forming a T-shaped plug having increased contact... Method for forming a T-shaped plug having increased contact...

1998-11-30

2001-03-27

Smith, Matthew (Department: 2825)

Semiconductor device manufacturing: process

Coating with electrically or thermally conductive material

To form ohmic contact to semiconductive material

C438S598000, C438S599000, C438S622000

Reexamination Certificate

active

06207545

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to semiconductor manufacturing processes, and more particularly, to a method for forming a contact plug or via having increased contact area.
BACKGROUND OF THE INVENTION
In semiconductor manufacturing, plugs are used to connect conducting layers, such as metals and doped layers.
FIGS. 1-3
show cross-sectional views of a semiconductor substrate
100
, illustrating the steps of a conventional method for forming a plug. Turning to
FIG. 1
, an insulating layer
102
is deposited atop the substrate
100
. Next, a contact opening
104
is formed by etching through the insulating layer
102
. Then, a barrier metal layer
106
is deposited into the contact opening
104
and atop the insulating layer
102
. A first conducting layer
108
is deposited into the contact opening
104
and atop the barrier metal layer
106
.
Turning to
FIG. 2
, the portion of the first conducting layer
108
atop the insulating layer
102
and the portion of the barrier metal layer
106
atop the insulating layer
102
are removed by chemical mechanical polishing (CMP). The portion of the first conducting layer
108
inside the contact opening
104
remains to form a plug
110
.
Turning to
FIG. 3
, a second conducting layer is deposited atop the plug
110
and the first insulating layer
102
. Using conventional photolithography and etching techniques, portions of the second conducting layer are removed, leaving a conductive structure
112
above the plug
110
. The etching is controlled to stop at the first insulating layer
102
. As shown in
FIG. 3
, the plug
110
and the conductive structure
112
may not be in full contact. This undesirable result may occur because of misalignment between the conductive structure
112
and the plug
110
or because of differing dimensions between the conductive structure
112
and the plug
110
.
What is needed is an improved method for forming a plug having an increased contact area.
SUMMARY OF THE INVENTION
A method for forming a T-shaped plug on a semiconductor substrate is disclosed. The method comprises the steps of: forming a first insulating layer atop said substrate; forming a second insulating layer atop said first insulating layer; patterning and etching said first insulating layer and said second insulating layer, stopping at said substrate, to form a contact opening; removing a portion of said second insulating layer surrounding said contact opening; forming a barrier metal layer along the walls of said contact opening and atop said second insulating layer; forming a first conducting layer into said contact opening and atop said barrier metal layer; and removing a portion of said first conducting layer and said barrier metal layer atop said second insulating layer, leaving a plug formed of the remaining portion of said first conducting layer.


REFERENCES:
patent: 5939788 (1999-08-01), McTeer
patent: 5960320 (1999-09-01), Park
patent: 5980657 (1999-11-01), Farrar et al.
patent: 5985753 (1999-11-01), Yu et al.
patent: 5989998 (1999-11-01), Sugahara et al.
patent: 5990015 (1999-11-01), Lin et al.
patent: 6001414 (1999-12-01), Huang et al.
patent: 6001683 (1999-12-01), Lee
patent: 6001735 (1999-12-01), Tsai
C. Y. Chang S. M. Sze, VLSI Technology, 1996, The McGraw-Hill Companies, Inc., pp. 419-420 and 444-445.

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