Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
1999-02-22
2001-06-26
Bowers, Charles (Department: 2813)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S622000, C438S625000, C438S627000, C438S628000, C438S660000, C438S663000
Reexamination Certificate
active
06251771
ABSTRACT:
FIELD OF THE INVENTION
The instant invention pertains to semiconductor device fabrication and processing and more specifically to a method of passivating a copper-containing layer after it is chemical-mechanically polished.
BACKGROUND OF THE INVENTION
Future electronic devices will be required to be smaller, faster, and consume less power than present devices. One means of achieving at least one of these requirements involves the incorporation of copper in the conductive interconnects of the device. However, conductive layers which are comprised of fairly substantial amounts of copper are difficult to etch. Hence, it is difficult to form patterned structures using a material which is comprised of any appreciable amount of copper using standard etching techniques.
A method to form structures out of copper-containing conductors is referred to as a “damascene” method. The damascene method involves forming a trench and/or an opening in a dielectric layer which is to lie beneath and on either side of the copper-containing structures. Once the trenches and/or openings are formed, a blanket layer of the copper-containing material is formed over the entire device. The thickness of this layer must be at least as thick as the deepest trench and/or opening. After the trenches and/or the openings are filled with the copper-containing material, the copper-containing material over the trenches/openings is removed, preferably by chemical-mechanical polishing (CMP), so as to leave the copper-containing material in the trenches and openings but not over the dielectric or over the uppermost portion of the trench/opening.
A problem with this technique is that it does not provide for a means of inhibiting the oxidation of the copper-containing structures when the device is subjected to an oxygen ambient.
SUMMARY OF THE INVENTION
An embodiment of the instant invention is a method of passivating an oxygen-sensitive material (such as copper) from oxidation by subjecting the material to a hydrogen-containing (or deuterium-containing) plasma before subjecting the device to an oxygen ambient for any appreciable time.
An embodiment of the instant invention is a method of forming an electronic device over a semiconductor substrate and having at least one level of metallic conductors, the method comprising the steps of: forming a dielectric layer over the semiconductor substrate, the dielectric layer having openings; forming a layer of the metallic conductor on the dielectric layer; removing a portion of the layer of the metallic conductor on the dielectric layer; and subjecting the exposed metallic conductor to a plasma which contains hydrogen or deuterium so as to passivate the metallic conductor. Preferably, the plasma contains a substance selected from the group consisting of: NH
3,
N
2
H
2,
H
2
S, and CH
4,
and the metallic conductors are comprised of a material selected from the group consisting of: copper, copper doped aluminum, Ag, Sn, Pb, Ti, Cr, Mg, Ta, and any combination thereof. The step of removing a portion of the layer of the metallic conductor is, preferably, performed by sputtering off a portion of the metallic conductor, chemical-mechanical polishing, etching, or a combination thereof.
Another embodiment of the instant invention is a method of forming an electronic device over a semiconductor substrate and having at least one level of metallic conductors, the method comprising the steps of: forming a dielectric layer over the semiconductor substrate, the dielectric layer having openings; forming a layer of the metallic conductors in the openings in the dielectric layer and on the dielectric layer; removing the layer of the metallic conductor on the dielectric layer using chemical-mechanical polishing; and subjecting the exposed metallic conductor to a plasma which contains hydrogen or deuterium so as to passivate the metallic conductor. Preferably, the plasma contains a substance selected from the group consisting of: NH
3, N
2
H
2,
H
2
S, and CH
4
, and the metallic conductors are comprised of a material selected from the group consisting of: copper, copper doped aluminum, Ag, Sn, Pb, Ti, Cr, Mg, Ta, and any combination thereof. The electronic device is, preferably, a memory device, a logic device, a DSP, a microprocessor, a transistor, a diode, or any combination thereof.
REFERENCES:
patent: 5677244 (1997-10-01), Venkatraman
patent: 5693961 (1997-12-01), Hamada
patent: 5705435 (1998-01-01), Chen
patent: 5723383 (1998-03-01), Kosugi et al.
S. Wolf and R. N. Tauber, “Silicon Processing for the VLSI Era, vol. 1: Process Technology”, Lattice Press, Sunset Beach, CA (1986), pp. 539-547, 559-564, 582-584.
Dixit Girish A.
Russell Stephen W.
Smith Patricia B.
Zielinski Eden
Bowers Charles
Brady III W. James
McLarty Peter K.
Smoot Stephen W.
Telecky , Jr. Frederick J.
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