ION CURRENT METHOD AS A HEAT SINK IN HIGH SPEED VLSI CHIPS


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Introduction :

Today’s era of High Speed Technology involves in minorization of length of
transistor gates as well as increase in number of transistors per chip along with increase
in speed of execution. There are various technologies available for us for the high speed
execution of task.


Nanoscale Transistor Hotspots :

As silicon transistor channel lengths decrease below 100 nm, the spatial volume
and number of lattice vibrational states gaining energy from electron scattering are also
decreasing. This results in extreme non-equilibrium phonon populations within the
device. Which impedes conduction cooling and reduces both the source injection and
drain series resistances. The impact on device design will be dramatic for transistors
below the 50 nm node.


Interconnect Heating :

Another on-chip thermal problem is the temperature rise in the metal interconnect
structures on chips. The trends to higher current interconnect densities, extreme
interconnect aspect ratios, and more metal layers are raising the metal temperature rise to
tens of degrees Celsius. In advances microprocessors, interconnect Joule heating becomes
more important due to aggressive technology scaling. The global interconnect
temperatures will significantly increase despite smaller projected increases in the chip
power density. With technology scaling, the maximum temperature in the chip (Tmax)
increases and the temperature gradient between the top metal lines and the silicon
substrate becomes larger. Increase in Tmax give raise to highest RC delays.


Generation of ion air current :

In the gaps of the layers the package covering, we introduces a specified gas
whose reactivity is absolutely zero with Silicon and Germanium but that should be
ionizable.


Circulation of Ion Air Current :
After the ionization, those ions gets attracted to +ve and –ve electrodes. Now,
shift the supply of power from 1&2 to 3&4 electrodes. The ions which were initially at
1&2 electrodes gets attracted to 3&4. Now shift power supply to 5&6 then again the ion
shift themselves towards 5&6 electrodes and so on.


Heat Sinking :
This air current on circulation throughout the chip passes through all the
important gates and picks the heat from every gate and gets heated up. This heated gas
passes through a cold heat sinks placed at specified location in the chip.