PQuest Cl2 back on-line

jim kruger jimkruger at yahoo.com
Tue Oct 16 11:16:54 PDT 2007


Cl2 seems to be working as of this morning.  A new Cl2
pressure regulator has been added so PQuest can be
independent of other systems.  Setting the regulator
is tricky so it is NOT a user activity, but you can
read the pressure through the window.  Ask for help if
you think there are issues.

This morning Elmer, then Cesar helped me.  The
pressure is now set for ~ 7 psig with high flow (43
sccm) and inicates ~ 9 psig for low (1.5 sccm) flows. 
I set 1.5 and read initially 1.3, settling to 1.4
sccm.

Historically, controlling low Cl2 flow has sometimes
been a problem if regulator "creep" allows the line
pressure to rise too far.  This can be addressed by
including a high Cl2 flow in a dummy step (i.e. Step 1
where you are verifying "wafer load OK" by reading
backside He flow).  Set 43 sccm for the 30 or 60
seconds of Step 1. Gas stabilization in Step 2 as
before.  The low Cl2 flow will settle much more
quickly from above than from below.  Then Step 3 as
before.

I am happy to help everyone, but in the interest of
efficiency, if each Research Group would designate a
"PQuest Expert" my time would go further.

Remember, the system has been cleaned and is in Cl2
mode so NO Fluorine recipes until further notice.

  If there is insufficient time to work through all
the saved-up GaAs Cl2 etches before the standard
switch-over date of the 21st, ask Mary to consider an
adjustment this month.

Happy Etching,

jimkruger




       
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