Semiconductor devices such as MEMS, MOSFETS, CMOS, nMOS,
pMOS, and BiCMOS comprise integrated circuits that perform complex and fast
operations. As the dimensions of these devices continue to decrease,
manufacturers must also fabricate increasingly smaller contacts in order to
optimize device speeds. Specifically, these contacts require nanometer
dimensions and low resistivity. As a result, manufacturers traditionally
fabricate these contacts from transition metal silicides like titanium, cobalt,
and nickel. Unfortunately, conventional methods of silicide fabrication require
complex, lengthy, and environmentally hazardous processes.
As an alternative method for silicide fabrication, ASU
researchers have developed a direct-write process for forming localized metal
silicides at one or more selected areas on a silicon substrate by using a
focused ion beam (FIB). This process fabricates metal silicides with both low
resistivity and nanometer dimensions. Consequently, the resulting silicides are
particularly suitable for use in a large variety of semiconductor devices,
especially those listed above, to serve as contacts, interconnects, and other
related structures in integrated circuits.
Potential Applications
- As a result of the need for new methods to produce
reliable silicides and to manufacture contacts in ever smaller, faster
semiconductor devices, the market for the direct-write imaging process using
FIB is poised to undergo rapid growth. The following provide some potential
applications for this process:
- Formation of self-aligned silicide structures directly on
gate oxide films
- Application to other metal-silicon systems such as Ni,
Pd, or Cr
- Introduction of necessary dopants for optimized device
function
Benefits and Advantages
- Low resistivity – allows fabrication of submicron
structures without use of resist-based lithography methods
- Maskless technique
- Nanometer-range dimensions – process refinement with
regard to thinner initial layers, anneal time and temperature, reduced beam
energy, and improved beam confinement allows improved linewidths
- Flexibility of FIB system – enables the study of
nanostructured silicides for novel devices or mesoscopic electron transport
structures.
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