Development of low-voltage hybrid (electronic – x-ray) nanoscope for nanotechnology.
Gelever V.D., Usachev E.Y., Manushkin A.A.
Moscow State University of Technology, Engineering, Scientific and Production Center of NDT,
5 Sokolinaja gora st., 22, 105275, Moscow, Russia
e-mail: [email protected]
To conduct studies of nanostructured objects by electrons and X-ray with high technical
parameters a low-voltage hybrid nanoscope (LVGN) of economical type has been developed for 115kV range applications.
LVGN is a version of the hybrid (electronic – x-ray ) nanoscope (GN) [1,2] reduced in size and
a significantly simplified (Fig.1a). The main element of the device is an electron-probe module (EPM)
on the tabletop , which consists of an electron-optical system (column) for electron beam focusing, the
pumping system based on the ion pump, removable chambers, object tables, detectors for secondary
and transmitted electrons and X-ray detectors. Nanoscope column is installed, so that the electron
gun
is on the bottom, and the objective lens (OL) is at the top, and there is easy access for
placement of the camera lens, tables and detectors. Power supply and control is conducted with two
blocks from a PC, which are arranged separately from the EPM. The column provides a resolution of
20 nm for secondary electrons and 10 nm - for the past (Fig.2b). Moreover, to increase the resolution
for 1-5kV range applications an additional intermediate acceleration for primary electrons was
introduced in the column in the space from the anode to the median plane of OL.
For the X-ray nanoscope mode of operation, there is installed on a special table a target (thin
metal film) on a vacuum - tight substrate, which X-ray is passing through on air to the object and X-ray
detectors (Fig.2 c) . High-resolution X-rays is provided by the use of micron and submicron substrates
Be, Si3N4, C et al., which minimize the distance between the object and the electron beam on the
target (focal spot). To focus the electron beam on the target in the scanning mode, a scintillation
detector is used, which arranged as close as possible to the target, that allows you to record almost
all the X-rays from the target. Next, the detector is moved with decreasing of aperture to operate in a
scanning mode, or it is replaced by X-ray or the projection matrix for the mode, where the beam stops
at some point of the target.Resolution in the scanning mode is determined by the minimum size of the
focal spot (FS), an aperture of X-ray registration, referred to the object plane, and the number of
detectors. For layered images of the objects it is advisable to use several detectors, that will record
multiple images from different angles. Using high-resolution detectors and optimization of the electron
beam parameters, a target resolution of 0,1mkm can be obtained in scanning mode, and 50nm - in
projection mode. Resolution for X-rays depends on the adsorption and phase contrast object details,
object thickness and accelerating voltage.
Performance of LVGN is on par with most table top SEM, but has more functions and
substantially lower cost. If necessary, the device can be added with a probe microscope and X-ray
spectrometers. The construction of nanoscopes is proved on several experimental models, allowing us
produce economical equipment consistent with the customer specifications.
1.V.D.Gelever, E.Y.Usachev,A.A.Manushkin ANALITICS, 2015, 3 (In Russian )
2. Vladimir D. Gelever, Alecsey Al. Manushkin, Evgeniy E. Usachev NANO2014, Моscow
http://www. nano2014.org›thesis/view/4093
a)
b)
c)
Fig.1 a) Appearance of two electron-probe modules GN and LVGN between them .
b) LVGN in scanning electron microscope mode with object camera, object table and
secondary electron detector; c) LVGN with X-ray detector