the end of the week, I interviewed an early champion of immersion and
a true litho guru, TSMC's Burn Lin. I have seen Burn in action at other
conferences and symposia many times over the years, and his technical
acumen, outspokenness, and wit have always provided a welcome antidote
to what were often dour and dry proceedings. When the industry faced
daunting red-brick-wall showstoppers in its hell-bent pursuit of 157
nm as the bridge technology to the next generation, Burn was a voice
in the wilderness, crying out for sanity and a thorough examination
of the 193-nm wet approach. His wake-up-call presentation in mid-2002
(ironically at a 157-nm workshop) was a critical turning point in what
has become the industry's full-court press to get immersion into production
in the 2006–2008 time frame.
described the sometimes-arduous task of building a coalition of the
willing, both among the suppliers and the chipmakers. "One key
point is that we had to convince the equipment suppliers and the materials
suppliers to change their roadmaps. Of course it was not easy, but fortunately,
TSMC is a big customer of ASML. . . .We had a lot of discussions between
ASML and us about going into immersion. The argument I heard most often,
almost from all suppliers, is that they have spent so much money [on
157 nm], hundreds of millions of dollars, so I asked them, 'are you
still spending it?' They said, 'sure,' so I said, 'the sooner you stop,
the sooner you stop wasting your money.' That was my counterargument.
order to convince the suppliers, actually I had to line the users up.
It was no good if TSMC was the only company that said they needed that.
All the users and all the infrastructure would need to be there. So
I did have to spend a lot of time talking to other semiconductor companies
to convince them that [immersion's] the way to go. Of course, it was
not an easy task. But then we got positive feedback, won one company
over, which helped me to win over another one, and also it helped to
convince the supplier."
he believes that immersion systems will eventually reach acceptable
productivity levels, Burn told me that he questioned the wet tools'
big price tags. "We are seeing the potential of the immersion scanner
approaching the throughput of the dry scanner, even though now it's
not the case. But we're not seeing any particular problem that [would
prevent it from] approaching that of the dry scanner.
the tool itself is a little bit more expensive. It's more expensive
than we had calculated. If you think about it, there's no expensive
extra part in the scanner. The lens has the same elements and they cut
the last element by half and fill it with water, so big deal. There's
the water head and so forth, a few mechanical parts, no tremendous high
precision required in those. We don't see a reason for extra cost. .
. .But it is more expensive, I think probably because of trying to recover
the development costs of immersion and maybe also trying to recover
the development costs of 157," he added, laughing.
had a lot more to say about the state of immersion during our chat,
commenting on many of the technical challenges as well as updating TSMC's
own IML roadmap. Look for more of our discussion in an upcoming issue.