| The Chemical Technology Division at
Oak Ridge National Laboratory collaborated with SEmiconductor MAnufacturing TECHnology
(SEMATECH), a consortium of ten leading semiconductor and chip-making companies in the
U.S., to develop a viable process for the next generation of high-performance chips.
Copper is poised to replace aluminum as the main on-chip conductor for all types of
integrated circuits. The incorporation of copper poses strong challenges in materials,
processes, ultra-pure water usage, and the impact of copper-containing waste discharges to
the environment. These challenges must be met within acceptable standards to manufacture
high-performance semiconductor chips of the future. To date, good quality deposits have
been obtained while extending the life of the electroplating solution by more than 100%. Technical Issues
- Copper is known as a fast diffuser and can act to
"poison" an active device, for example, the source/drain/gate region of a
transistor. To mitigate the undesirable effects of copper diffusion, development of
advanced diffusion barriers is required.
- Implementation of an entirely new manufacturing technique is
required.
- The problem of uneven current densities causes trenches and
vias in the circuitry to be filled unevenly. This problem will be exacerbated as
interconnects are made smaller, approaching 0.07 micron.
- Copper requires large amounts of ultra-pure water. About 40%
of the operating costs of a semiconductor fabrication plant will be for production and use
of ultra-pure water.
- Water recycle, water reuse and the release of copper to the
environment are critical.
For further information, contact
M. R. Ally
Oak Ridge National Laboratory
Email: allymr@ornl.gov
|
Copper chemical-mechanical planarization (CMP) for damascene
structures involves developing a polish process that minimizes the pattern density and
feature size effects associated with typical CMP processes. Development is complicated due
to new barrier materials and the lack of commercial slurries.
Accomplishments
- ORNL engineers working in conjunction with SEMATECH have
extended the life of the copper bath by over 100% through analysis and process
modifications.
- The quality of copper electro-deposited on the wafer was
confirmed by detailed elemental analysis and scanning electron microscopy.
- Extension of the life of the copper bath means cost savings
and lower disposal costs.
- Methods for recovering copper from spent CMP slurries are
being tested.
|
