Critically Low Chemical Inventory

Ed Myers edmyers at stanford.edu
Thu Jun 11 12:50:16 PDT 2009


All,

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.

Regards,
Your SNF Staff




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