Paul,
Re: "Basically, IBM's much vaunted Copper Metallization technology,
with its added expense and process difficulty, is comparable in
performance, at the 0.25 micron level, with Intel's Aluminum based process."
I would like to add my two cents on this topic ... and ... I am more
pessimistic on Intel's position with regards to Copper.
M. Bohr gave a paper at the Dec '95 IEDM conference addressing the role
that frontend device capacitance (gate, S/D and overlap) and backend
interconnect resistance/capacitance play in determining the speed of circuits in
various generations of technology (.5um, .35um, .25um, .18um ...).
His calculations predicted that at roughly .25um, the interconnect delays (RC)
were equal to the device capacitance delays while for each new
generation (.18um, .13um ...), the interconnect delays became more and
more important in actually determining the ultimate speed of a CPU. At that
time, Intel decide to solve this problem by reducing the interconnect
capacitance with Low K dielectric materials. This has turned out to
be very difficult with many integration issues and might not be available
for .18um technology.
Copper damascene processing provides a number of benefits (some you have described):
1) Lower sheet resistance and thus lower resistance for small metal lines
2) Electromigration reliability issues are not a factor (unlike for Aluminum)
3) Potentially, much lower cost !!! This is due to a simpler process
(no more dielectric CMP and dielectric dep gap fill issues) ... AND ... much
better yield due to CMP of metal versus etching. This could be the
compelling reason to go to Cu interconnect (cost/yield)
Another fact is that IBM is indeed much further ahead in this technology than
Intel. At .13um technology, Intel will have to use this technology to
solve the technical problems #1 and #2 above. I agree that Intel will be
able to hold their own on performance at .25um and even probably .18um, but
they need to get seriously working on this NOW. (Inside word is that this
is a very high priority now at Intel)
IBM is a very serious competitor from the performance standpoint ... reviewing
technical papers, IBM is Intel's equal in devices and IBM has a definite
advantage in interconnect. Intel continues to have a significant advantage
when it comes to high yield in volume manufacturing ... and Intel
does have lower wafer/part costs at this point (.25um). It has been interesting
to me to see all the companies "flocking" to IBM as a foundry. I have
been stating on a number of threads (AMD, CYRIX ...) that the Far East
foundries are no match for Intel's device performance at .25um ... I think
this mainly explains the surge of IBM business. I wouldn't take IBM lightly ... though
I am not sure how AMD, IDTI, NSM will make money contracting out the Fab'ing
of their CPU's.
Just my thoughts,
Yousef |
