Hi Jianhua,

Chances are that your SiO2 isn't continuous.  This can be a uniformly
discontinuous film (islands) or by random point defects.  Either way, a short
will form between the Ti layers.  Also, are you sure you are putting down 250
nm of SiO2?  If you haven't characterized your deposition rate recently, then
you may be putting down less of a film than you think.  One more thing, make
sure to presputter the SiO2 target sufficiently, if you don't, then you'll be
mixing Ti with your initial SiO2 thereby rendering it not so insulating.  Good
luck!

Paul Sunal

Ph.D. Candidate
Pennsylvania State University
266 MRL Bldg.
University Park, PA 16802
814.865.0755

>I had sputtered a silicon dioxide membrane,the structure is as this:
>Silicon wafer---Ti electrode(60nm)---Silicon dioxide(250nm)---Ti
>electrode(100nm)
>All the three membranes are deposited by Magnetron Sputtering.
>The power of sputtering is 120W for Ti and 200W for silicon dioxide.
>The area of up electrode is about 1cm^2.

>The problem is,the resistance between up electrode and bottom >electrode is
only 170¦¸!
>What's wrong with my silicon dioxide membrane?
>What's the most possible reason lead to a conductible silicon dioxide
>membrane?