Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
1999-08-06
2001-11-13
Nelms, David (Department: 2818)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S636000
Reexamination Certificate
active
06316345
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to a method of forming metal contacts in a semiconductor device, and, more particularly, to a method of removing an anti-reflective coating layer using a high-temperature fluorinated chemistry to provide a semiconductor device having a more consistent planar surface at the conclusion of the metal contact forming step.
2. Description of the Related Art
Anti-reflective coatings have been used in the fabrication of small dimension integrated circuits (ICs) to provide better control over the photolithographic process. In particular, inorganic BARCs (bottom anti-reflective coatings) have been used during the contact hole masking step to reduce the reflections from the underlying topography substrate and thereby provide better control over the width of the photoresist mask openings which are used to form contact holes of a desired width.
FIGS. 1A-1D
illustrate a conventional method of forming metal contacts for a semiconductor device in which an anti-reflective coating layer is used to reduce the reflections from the underlying topography substrate. The semiconductor device includes a substrate
10
, an active region
15
formed in the substrate
10
, an insulating layer
20
, which is typically a silicon dioxide (SiO
2
) layer, disposed on top of the substrate
10
, a BARC layer
30
disposed on top of the insulating layer
20
, and a photoresist layer
40
in which mask openings
45
are formed by a conventional photolithographic process.
The semiconductor device illustrated in
FIG. 1A
is etched to form openings
50
through the BARC layer
30
and the insulating layer
20
.
FIG. 1B
illustrates the semiconductor device having the openings
50
and the photoresist layer
40
removed. On top of the semiconductor device illustrated in
FIG. 1B
, a metal layer
60
, e.g., tungsten (W), is deposited on its surface. The resulting structure is shown in FIG.
1
C.
Subsequently, the metal layer
60
is planarized by a conventional polishing process. The metal layer
60
is polished until the entire surface of the BARC layer
30
is exposed and the metal contacts
70
remain. The resulting structure is illustrated in FIG.
1
D.
In the conventional method of forming metal contacts, the BARC layer
30
that remains after the metal layer
60
is polished has thickness variations and surface inconsistencies
80
that make post-polish defect inspections extremely difficult. It is thus desirable to provide a semiconductor device having a more consistent planar surface at the conclusion of the metal contact forming step to improve the rate and the quality of post-polish defect inspections.
SUMMARY OF THE INVENTION
The invention provides a method of forming metal contacts in a semiconductor device in which an anti-reflective coating layer used to provide better control over the photolithographic process is removed by high-temperature fluorinated chemistry. The removing step may be carried out just after the metal layer for forming the metal contacts has been deposited and polished, or before the metal layer for forming the metal contacts is deposited and polished. The removal of the anti-reflective coating layer in this manner, reduces the amount of thickness variations on the planar surface of the semiconductor device and leads to an improved and less difficult post-polish defect inspection.
REFERENCES:
patent: 6001541 (1999-12-01), Iyer
patent: 6042999 (2000-03-01), Lin et al.
patent: 6060379 (2000-05-01), Huang et al.
patent: 6066569 (2000-05-01), Tobben
Advanced Micro Devices , Inc.
Foley & Lardner
Le Dung A
Nelms David
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