Re: RF Conductivity of thin Mo film

Peter Simon wrote:
> 
> I am very interested in predicting the RF reflection and transmission
> (at a frequency of 2.6 GHz) through a thin layer of Molybdenum (Mo)
> that may be sputtered onto a 2 mil plastic substrate. The Mo
> sputtering process will be very slow: over a cumulative time span of
> several thousand hours the thickness will build up to as much as 500
> Angstrom.  I'm interested in looking at the RF properties as a
> function of the thickness of the layer from 0 to 500 Angstrom, and as
> a function of temperature from 90 to 400 K.
> 
> I know how to do the calculation given the value of the conductivity
> of Mo: for a thin layer of good conductor the metal can be modeled as
> a sheet resistance R = 1/(sigma*t), where sigma is the conductivity
> and t is the thickness.  For a thicker layer one can use a more
> rigorous transmission line analogy.  However, from browsing the
> literature, I've seen that the effective conductivity depends on
> several factors, including temperature, film thickness, and the manner
> in which the Mo is arranged: single crystal, polycrystalline, or
> amorphous.
> 
> This deposition is going to occur in a vacuum, due to ion bombardment
> of a molybdenum surface, at temperatures that vary over the range of
> 90 to 400 K.
[snip]

Are you interested in the amount of Mo deposited and then RF
properties, or something else?  Why not have a naked quartz oscillator
crystal in there and track the change of resonant frequency with
increasing mass?  It's a commercial system.  Do your RF measurements
concurrently, already knowing the film thickness to excellent accuracy

Google
quartz "deposition monitor"  172 hits
"deposition monitor"         416 hits

The only no-no is that quartz undergoes a solid state twinning
transition at 573 C.  Don't go above 500 C at the crystal.

--
Uncle Al
http://www.mazepath.com/uncleal/qz.pdf
http://www.mazepath.com/uncleal/eotvos.htm
 (Do something naughty to physics)