[labnetwork] cost recovery

[John Shott]

Michael, Rick, et al:

In our case, the chemical cost of a tool ... spinner, wet bench, etc. is 
built into the tool cost.  (Well, approximately, we just make a ball 
park estimate and lump a tool into one of our three categories.  So, 
when a track is enabled, you are racking up equipment charges that 
include the cost of resist, developer, etc.  Same with the wet benches 
... chemical cost is included in the tool cost.  Precious metals are our 
only exception to that rule (although germane cost at the epi reactor 
should be another exception ...)

In terms of interlocking wet benches, we have tried to do this in a way 
that doesn't jeopardize potential safety ... use of a spray gun to rinse 
off a spill.  In general, we've been successful by interlocking the 
level switch that is found in most hot pots ... if the tool is not 
enabled, it thinks that there is low chemcial level and won't let heat 
be applied to the hot pot.  For the few benches where we still have hot 
plates ... I hate hot plates ... we also interlock the heater power.  No 
interlock enabled, no heat.  Finally, although I can't tell you exactly 
what we've interlocked, we also interlock the SRDs associated with a wet 
bench.  Nobody will try to stick their hand in a SRD in an emergency 
situation.

Since we have few different "tiers" of equipment rate, we probably do 
have cases where we "make money" on some tools and "lose" on others.  
We've always felt that tracking detailed cost on a per-tool basis would 
be onerous.  Particularly because our university accounting system 
doesn't provide us very good resolution in that regard.  Just 
distributing nitrogen costs on a per-tool basis would be a bit tricky.  
A typical dry pump used for anything other than a load lock consumes on 
the order of 1 CFM of nitrogen ... at our rate, that's $4k annually.  
We've certainly been through a bunch of audits ... but never been 
"written up" because we don't charge a different rate for each tool.  
Typically, they are so focused on the cap, that they forget to ask about 
this ...

Let me know if you have any other questions.

John


On 3/20/2013 7:25 AM, Michael Khbeis wrote:
> John, and the other site managers, I would like to understand how you charge/monitor use for wet chemical benches and chemical consumption.  Our consumption (resists, solvents, acid/base) is around $80-100K/year and climbing.  I built in CORAL/BADGER capable interlocks into the design of the benches, but the debate with our EH&S was in disabling the bench without impacting safety (e.g. ability to rinse a glove or sample) and with our staff and users on the nuisance of having to log multiple benches in and out when moving from station to station (e.g. going from develop to BOE bench). With so many users simultaneously moving in and out of the benches, we didn't have a good idea of how to manage this, so the chemical overhead is lumped into the daily rate.  This unfortunately fostered a "it's free" mentality.  I would catch a grad student pouring a liter of sulfuric to do piranha on one wafer (even though we maintain pre and post metal tanks for piranha).  Any feedback and insight on this topic is greatly appreciated.
>
> Best regards,
>
> Dr. Michael Khbeis
> Associate Director
> Microfabrication Facility (MFF)
> University of Washington
> Fluke Hall, Box 352143