Re: SEM of magetic materials

From: Gary G (see.signature_at_bottom)
Date: 03/11/05 

Date: Fri, 11 Mar 2005 07:21:10 -0800

On 11 Mar 2005 02:57:15 -0800, "vsoares@inesc-mn.pt"
<vsoares@inesc-mn.pt> wrote:

>Hi all,
>
>I'm not a SEM especialist but have often to use the SEM at work.We have
>a S2500 Hitachi tungsten filament scope and we have sometimes to look
>at magnetic sensors.One of the problems is that the sensor is on top of
>SiO2 so I cannot get enough contrast.
>Is there some etchant I could use to increase the contrast?What worries
>me is that the sensor is only circa 200 A high and that any etch will
>destroy it.
>
>Thank you in advance
>
>
>Virginia Soares

If the sensor is on top of SiO2, then more than likely, the whole
specimen will charge. when this happens, you will definitely lose
contrast. To avoid charging, coat the specimen with Au/Pd or Pt.
However, doing so will render the specimen non-functional since it
makes the specimen conductive. The coated specimen should be on a pin
stub or other type of mount so that it is connected to ground.

A feature size of 200A high is a small dimension. What is the x & y
size of the sensor and what is its composition? If it is metal, then
backscatter will produce lots of contrast and also eliminate the need
for coating.

Gary Gaugler, Ph.D.
Microtechnics, Inc.
Granite Bay, CA 95746
916.791.8191
gary@microtechnics dot com

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