Yun,

I do not know the vapor pressure of CCl4 but I assume it is low. If you do
not have enough head pressure in your cylinder the gas will not flow. One
way to overcome this problem is to heat your cylinder. The only problem with
this method is the gas lines also have to be heated and to a temperature
higher than the cylinder or the gas will condense back into a liquid. If you
can flow the CCl4 without the CF4 you may try to turn down the CF4 flow and
or pressure. If the CF4 and the CCl4 are on the same low-pressure manifold
the CF4 can starve off the CCl4

Best regards,

Glenn Silveira

-----Original Message-----
From: Yun Xi [mailto:[email protected]]
Sent: Wednesday, June 30, 2004 7:31 PM
To: [email protected]
Subject: [mems-talk] Trouble on CCL4


Hello,

We used mixture of CCL4 and CF4 to do gold dry etch, but recently it doesn't
work. It seems CCL4 run out. We contacted Scott Specialty Gases to order
CCL4. The company told us their cylinder will not have a diptube or pressure
pad and we have to invert the cylinder to reomve the product. We know that
means CCL4 is liquid phase in cylinder. When we took our old CCL4 cylinder
out from system, we found there is stiil liquid inside. We let the cylinder
upside down and connectd to system again, liquid CCL4 come out and MFC out
of control.

We would like to know how to deal with this situation to have gas phase
CCL4? We are appreciated your help.

Yun