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Metal Deposition for Microelectronics Using CO2 as a Solvent
Title: Director of R&D
Phone: (919) 313-2108
Email: jdeyoung@micell.com
Title: Director of R&D
Phone: (919) 313-2108
Email: jdeyound@micell.com
MiCell Technologies, Inc., proposes a new process for the deposition of metallic
thin films of copper, ruthenium, titanium, and other metals used as barrier
layers, seed layers, and interconnects. This process would replace the current
electroplating approach used in filling deep trenches and forming thin films
in microelectronic circuit manufacturing. The electroplating process generates
large quantities of aqueous wastes with copper ions and other dangerous chemicals
that must be treated in place. The process being proposed utilizes liquid or
supercritical carbon dioxide as the solvent. In addition to being environmentally
benign, this process also will provide additional control of the metal deposition
processes to create high-quality films and electrical interconnects. This project
is part of an overall strategy to replace all aqueous and organic solvents
in microelectronics fabrication.
The proposed fluid displacement deposition process utilizes a two-step approach
to the formation of the deposited metallic layers. In the first step, organometallic
precursors will be dissolved in either liquid or supercritical carbon dioxide.
The wafer to be coated will be immersed in either the liquid or supercritical
solvent. This solution will be displaced either with carbon dioxide itself
or by a second fluid, such as helium, in the supercritical state. This displacement
step will cause the formation of a thin film that will result in the deposition
of the organometallic precursor on the wafer surface. Because of the low surface
tension and viscosity of the carbon dioxide phase, the precursor will penetrate
uniformly into the narrow gaps on the surface of the circuit. After this film
displacement step, the system can be heated and a reducing agent, such as hydrogen,
can be introduced to remove the organic ligands bound to the metal atoms. After
the reduction step, a solid metallic layer will remain on the surface, which
will form the desired interconnect or thin layer structures.
Phase I will determine the more important operating variables in both the
liquid and supercritical carbon dioxide surface deposition processes. Phase
II will involve the design of a metallization tool that will meet the operating
requirements of industrial microelectronics fabrication. Because of the demand
for faster, more sophisticated structures in modern electronic products, copper
interconnects and metallic barrier and seed layers will play an increasing
role in device fabrication. This environmentally benign process will have a
preferred place in the marketplace.
* Information listed above is at the time of submission. *