Critically Low Chemical Inventory
edmyers at stanford.edu
Thu Jun 11 12:50:16 PDT 2009
This spring we have had extreme difficulty in receiving delivery on a
number of critical chemicals. Many of you may have seen the staff
mixing 50:1 HF. We are forced in to this approach because of HF
mixing equipment failures at the manufacture. This is close to being
resolved, but we still have a week or so to go.
What you may not know is the problems we are having with our supplier
of photolithography chemicals. The critical chemicals where we are
in a shortage situation include the MF-26A the 3612 developer, EC13
the edge bead removal and PRX127. As a result we will be limiting
the availability of these chemicals.
Currently we only have inventory of MF-26A to support two weeks of
usage on the coat tracks (this does not include any manual develop
usage). The email we received yesterday from the chemical supplier
gave a 4 week delivery date. This leaves us with a 2 week short
fall. Please note, these chemicals were ordered in time. It is the
supplier who is not able to support their normal delivery schedule.
As a result we are immediately implementing MF-26A restrictions which
includes the removal from the area of the deep beakers used for
manual develop. These beakers are being replaced by short glassware
until we receive our delivery. Often we see huge amounts of
developer being used for single or very few wafers. The SVG
developer tracks use ~50 ml per wafer for development (that is 50ml
total for both develop steps and not each step). There is no need to
pour two or three inches of developer into a beaker when manual
developing. Also, we will only leave one bottle of MF-26A in the fab
for manual develop. Please use it sparingly.
What you can do regarding MF-26A conservation
1) Develop your wafers on the SVG track. You will use thousands
times more developer if you used a beaker.
2) Use the correct sized beaker for your sample. Don't develop
pieces in a 4" beaker.
3) Gently remind your lab members their excessive use of developer
may result in no one being to develop their wafers in a couple of weeks.
Remember each bottle which is used for manual develop cost about 1
day of track usage and as a result we will run out a day earlier.
We will also see a short fall with ED-13. This chemical is only used
in the coat tracks, so changes made to control it's usage will not be
obvious to the lab member community.
Finally, we are also struggling with PRX127. Our inventory and the
delivery date will put us in a close situation. If we follow normal
usage trends, the scheduled delivery will arrive just as we will be
running out. If we see a spike in usage, like we did last weekend,
or a delay in the delivery date we could also run out of this
chemical. Especially during this time (and we would hope at all
times) please adhere to the chemical change out schedule. It is
important that we do not drain and replenish the pots before they have expired.
Most of the delivery problems we are facing has resulted from the
consolidation of the older product lines and the lower demand for
some of these chemicals. The chemical supplier request long range
forecasts from it's customers. Depending on the customers forecast
the company schedules their manufacturing runs. As a result we are
all placed on a balancing act tied to their manufacturing
facility. Any problems the manufacturing line has, or any poor
forecasting has a huge impact on the end of line customers such as SNF.
Thank you for your understanding and most importantly your chemical
conservation during this shortfall.
Your SNF Staff
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