AVS 61st International Symposium & Exhibition
    Helium Ion Microscopy Focus Topic Thursday Sessions
       Session HI+2D+AS+MC-ThA

Paper HI+2D+AS+MC-ThA3
MEMS Temperature Controlled Sample Stage for the Helium Ion Microscope

Thursday, November 13, 2014, 3:00 pm, Room 316

Session: Nanoengineering with Helium Ion Beams
Presenter: Jose Portoles, Newcastle University, UK
Authors: J.F. Portoles, Newcastle University, UK
P.J. Cumpson, Newcastle University, UK
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The Helium microscope allows the imaging of samples with magnifications beyond those of electron microscopes with the added advantages of directly imaging insulators without being so critically dependent on a need to conductive coating the samples. This facilitates the imaging of for instance organic structures without the need of surface modification. The large depth of focus allows simultaneously focusing details of the sample at different depths. When using a temperature controlled stage this allows the samples to stay focused as thermal expansion produces vertical displacements of the sample surface, however due to the large magnifications in-plane thermal expansions are still an issue. We have investigated a solution based on a thermally actuated X-Y MEMS stage by exploiting the ability of MEMS actuators to provide smooth electronic control of lateral displacements in the micron range in order to compensate for lateral thermal expansion at the point of observation. The difficulties involved in producing relatively large out of plane displacements with a MEMS device can be neglected due to the large instrumental depth of focus. The device we present has been fabricated using a “silicon on insulator” (SOI) MEMS process, and can be driven at low voltages and currents using a standard vacuum feedthrough to the instrument's analysis chamber and compensate lateral thermal expansion in order to keep any spot on a small specimen in the field of view at high magnifications. The small size of the heating stage makes it rapid in its thermal response.