Drytek poly-etch using Freon-22

Len Booth booth at snf.stanford.edu
Fri May 23 15:36:53 PDT 2003

Drytek users -
        As you know by now, the F-115 is gone, and
has been replaced by F-22.
        Jim McVittie & Henry have done characterization
of the F-22 in the poly etch process.  The contact 
cleanup process is not working yet - additional process
changes are being developed by Jim McVittie this weekend.
Do NOT use the contact cleanup etch in the Dryteks
until Jim has finished developing a new process.

        Those of you using poly-etch recipes which now are
using F-22, a temporary multiplier must be factored into
the dial setting that you must now use for the F-22 (MFC-3).

MFC-3   flowing F-115   @ max setpoint 240= real flow of 240sccm

MFC-3   flowing F-22    @ max setpoint 240= real flow of 110sccm

        Therefore those of you using F-22 in MFC-3 should 
expect the setpoint range to be from 0 to 240 on the dial,
which will corespond to 0 to 110 sccm of F-22 measured flow
on the digital readout.

Examples for setting using F-22 in MFC-3:

	dial setting	digital flow	real F-22
			readout		Flow sccm
	240		238		110
	120		119		 55
	060		062		 27
	044		044		 20
	030		031		 13

        By next week we hope to correct the old recipe spec

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