Request for W etch in PQuest

jim kruger jimkruger at
Fri Apr 14 11:30:47 PDT 2006

SpecMat Request for etching Tungsten in PQuest

I am currently experimenting with etching W in Drytek4
with SF6-N2.  Results are promising and I will
continue in Drytek4 if the recipe proves suitable for
deep sub-micron dimensions.  However, both my
experience and the literature indicate that lower
pressures than are possible in Drytek4 may be

The  P5000 can operate at somewhat lower pressure than
Drytek4, but still ~10 X higher than is easily
available in PQuest. In addition, transparent quartz
substrates are a problem for the P5000 wafer handler. 

Film:  200 nm sputtered W from LGAfilms.

Substrate:  Thermal Oxide / Si for tests, then quartz
100 mm wafers

Gasses:  SF6-N2

Power:  both literature and Drytek4 data indicate that
low powers are adequate (50 watts in Drytek4).

Etch Mask:  EBeam resist (MaN negative resist)

In some applications, MOS grade SOG (spin-on-glass) is
the substrate layer under the W.

EBeam patterned wafers are few and far between, so
total number of wafers is estimated as about a dozen.

WF6 is a very volatile etch product and SF6 is not
known for polymer deposition so chamber residues
should not be an issue.  An O2 clean can be run after
each session.  The new 1 week / month schedule for F
based etches should further eliminate chamber history

Jim Kruger

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