[Spm] RE: Depth of narrow trenches

[Li Ang]

Hi, Yi,
I guess it's aspect ratio other than tip radius may bias your
measurement in such a case. One simple way to check this issue is to use
a higher aspect ratio tip for example a tapping mode tip to scan again,
if the height changes, then you may expect tip shape affect your result
and some better tips such as whisker type tips from NT-MDT may be
helpful to obtain real height. Otherwise, you should think about what's
wrong with your sample. 

Li Ang
Nano Biomechanics Lab
Blk E3 #05-16, Division of Bioengineering
Faculty of Engineering
National University of Singapore
Tel.: +65 6516 6564
Fax: +65 6874 1658
http://www.bioeng.nus.edu.sg/nanolab/nanolab.html


Date: Tue, 11 Jul 2006 12:16:48 -0600
From: Youngwoo Yi <Youngwoo.Yi at colorado.edu>
Subject: [Spm] Depth of narrow trenches
To: spm at spmlist.di.com
Message-ID: <1152641808.44b3eb10c7d99 at webmail.colorado.edu>
Content-Type: text/plain; charset=ISO-8859-1

Hello,

My sample is a topographic patterns of lines. The pitches of the lines
varies from ~100 nm to 1000 nm. I am measuring the depth of trench using
contact mode AFM. The depth is much smaller than the expected one. I
expect ~ 30 nm but the measurment is only 3 nm. So I dought if the
height I measure is real of not.
As the trench becomes narrower it will be harder for the tip go into the
bottom of the trecnch. But considering tip radius of ~20 nm this happens
for trenches of width much larger than the tip radius. Do you know waht
is the limit of heigh measurement for the contact mode AFM?

Can the contact AFM give the accurate depth of the very narrow trenches
when the width of the trench is sub-micron meter? From what size of
trench we see the significant deviation of height from the real height?



--
Youngwoo Yi
Postdoctoral Research Associate
Physics Department and Liquid Crystal Materials Research Center
University of Colorado Boulder, CO 80309

Tel:303-492-4830 (O)
    E-mail: yiy at colorado.edu


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End of Spm Digest, Vol 24, Issue 5
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