Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
2000-02-10
2001-07-17
Nelms, David (Department: 2818)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C257S629000, C257S635000, C257S637000, C438S669000
Reexamination Certificate
active
06261945
ABSTRACT:
TECHNICAL FIELD
The field of the invention is that of integrated circuit processing, in particular circuits having low-K dielectrics and copper metallization.
BACKGROUND OF THE INVENTION
The relatively new field of copper-interconnect integrated circuits offers well known performance advantages, especially when the copper is combined with low-K or porous dielectric materials, such as amorphous carbon, FLARE and Naroglas, from Allied Signal and SiLK, available from Dow Chemicals. It has been found, however, that such a combination of materials is unexpectedly susceptible to corrosion from oxygen. The methods of blocking oxygen used in the prior art have proved to be ineffective, even though nitride and oxide are good barriers to oxygen, and an improved method of blocking corrosion is now required.
SUMMARY OF THE INVENTION
The invention relates to a structure and method for both blocking crack propagation and also for reducing oxygen diffusion into an integrated circuit and subsequent corrosion of the metallization of the circuit.
A feature of the invention is a composite crackstop structure in which corresponding elements of the crackstop are constructed simultaneously with the circuit interconnect elements; e.g. horizontal interconnect elements in the circuit have a corresponding structure in the crackstop and vias between interconnect layers in the circuit have corresponding structures in the crackstop.
Another feature of the invention is a crackstop structure in which the levels taper down in width, so that an upper level is contained within the limit of the next lower level, allowing for process tolerances.
Another feature of the invention is that the crackstop is constructed from the same material as the circuit interconnect members; i.e. the crackstop is susceptible to corrosion, rather than being corrosion resistant.
Another feature of the invention is the use of a metal structure capping the crackstop and inserted in an aperture within the protective dielectric layer.
Yet another feature of the invention is the use of a redundant oxygen barrier internal to the primary crackstop and placed between it and the guard ring.
REFERENCES:
patent: 5530280 (1996-06-01), White
patent: 6091131 (2000-07-01), Cook et al.
McGahay Vincent J.
Nye, III Henry A.
Tallman Kurt A.
Berry Renee R.
International Business Machines - Corporation
Nelms David
Petraske Eric W.
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