nitrogen vaporizer upgrade

Dear Labmembers and CIS Lab Occupants:

For the past few years, we have been working with Air Products on an
upgrade of our nitrogen vaporizer system. As you may be aware, Air
Products supplies our bulk liquid gases and, to some extent, the
facilities for vaporizing them to gas form so that they can be used
as process gases in our labs in SNF and CISX.

Collectively, we are now extracting anywhere between 3-4X the amount
of gaseous nitrogen that our vaporizers are rated for. Needless to
say, this is not the best way to run. Through a series of
negotiations, Air Products has generously agreed to donate equipment
and services to upgrade our vaporizers. In the current plan, Air
Products will use a tanker truck to provide a temporary N2 in order
to ensure continuous supply to the CIS and CISX buildings during this
transition. The temporary supply will be hooked up on Tuesday,
December 18 and there should be no noticeable change in
services. From Wednesday, December 19 through Friday, December 21,
the larger vaporizer and new N2 purifiers will be installed. Once
the new system is leak-checked and certified, it will go on-line and
the temporary N2 supply will be removed. During this time, metering
systems will also be installed in order to allow us to get a handle
on nitrogen usage. As you may be aware, liquid nitrogen is the
largest single expense in this building. We have been looking
forward for a long time for this upgrade; this should facilitate a
more reliable and cleaner supply of N2 for the building.

However, one aspect of this installation has the potential to affect
quality of gas delivered. For staging the installation, the gas
purifiers for bulk O2 and ultra-high purity N2 will need to be
bypassed. This is tentatively planned for Monday, December 10,
although we need to confirm this date. Air Products' testing
indicates that the current N2 purifier system does not significantly
improve the quality of the delivered gas so bypassing this should not
have a noticeable effect. However, the O2 purifier seems to be
somewhat effective at filtering particles (1357 particles >0.1 um at
the inlet versus undetectable amounts at the outlet.) So, please be
aware that between December 10, when the O2 purifier is taken
off-line and December 21, when the new O2 filter is installed, that
the quality of the O2 may be somewhat compromised. This is not
anticipated to affect most operations in SNF (namely, etches and
depositions) but critical operations, such as very thin gate oxides,
may be vulnerable. Please be aware of this when planning your experiments.

We apologize for the inconvenience these changes may cause. But
please understand that these changes are necessary to ensure reliable
and continuous bulk gas supplies. If you have any further questions
or concerns about this upgrade, please contact Ted Berg.

Paul Rissman