X-ray nanofocus microscope .
Gelever V. D. Manushkin A. A. Usachev E.Ju.
Moscow State Technical University for Radioengineering, Electronics and Automation
(MSTU MIREA),
5 Sokolinaja gora st., 22, 105275 Moscow, Russia
e-mail: gelgan@yandex.ru
Currently the X-ray nanofocus microscopes are practically unused in nanotechnology
because of their low resolution, large dimensions and high cost , although there is a great need
for getting information about internal structure of nanoobjects because many of their physical,
electrical and other properties are related to the internal structure . To get structural information
it is necessary to use destructive methods of control. Prepared according to various methods, the
chips or fractures of objects are then tested in an electronic , optical or probe scanning
microscopes to obtain information in one cross section. Furthermore, the layers of the objects
are removed mechanically or by an ion beam with the aim to reconstruct the entire structure. But
these destructive and costly methods do not provide full and real time information about the
internal structure .Today nanofocus X-ray microscopes with demountable X-ray tubes allow to
obtain resolution down to 50 - 100nm . The values of 20 - 30nm of resolution on biological
objects is achieved on synchrotrons using X-ray focusing optics.
To obtain nanoscale focal spots (10 -20nm ) and high contrast on nanoscale details of objects it
is necessary to work at accelerating voltages of 3- 10kV . With the transition down to the
nanoscaled electron beams and focal spots the beam current and X-ray intensity are sharply
reduced . It is practically impossible to get focusing via X-ray monitoring. One can quickly and
accurately focus the beam on the target through the relevant registration of elastically scattered
[1] or secondary electrons [2] from the target. In the scanning mode, one can see an image of the
target surface to assess the size of the electron beam and to control in time the integrity of the
surface, which gives the possibility to select an optimal place of beam stopping for the
projection beam mode . The secondary electrons because of their majority in number can be
more effectively collected through the inner channel of the focusing, objective lens ( OL ), and
thus one can operate at lower currents and beam sizes .
Also for the developed microscope there is a near focus mode when due to micron and
submicron substrates of Be, Si, Si3N4 and C the distance between the focal spot and the object is
power reduction of X-rays at the transition to the nanofocus range .
In projection mode X-ray flux diverges from the focal spot, passes through the object and forms
with absorption or phase contrast an enlarged image of the object on the position-sensitive X-ray
detector) . Spatial resolution is limited by the size of the focal spot . With the calibrated
displacement of the electron beam one can obtain a series of images to form a 3D image .
In scanning mode an electron beam is scanned over the target , and X-ray radiation passed
through the object is recorded by either scintillation or semiconductor detector with a small inlet
. Resolution is determined by the size of the hole at the detector entrance scaled to the object
plane , and the size of the focal spot . In the scanning mode on one pixel of the detector falls a
small amount of X-rays , so it is advisable to use a large number of identical detectors , which
would allow different angles to record X-rays passed through and to get a 3D image .
X-ray microscope could be converted into an electron microscope , if to withdraw under
the electron beam an object and to register past and secondary electrons . Actually the developed
microscope is an optimal hybrid of X-ray and electronmicroscope–a hybrid nanoscope [3]. It’s
design allows at low cost to include in the probe and optical microscopes to conduct
comprehensive studies of nanostructured objects. Now there are two prototypes being under
adjustment, and some results are shown on the pictures.
References
1.K.Minami,Y.Saito,H.Kai,K.Shirota and K.Yada 2009Proc.9thInt.Conf.X-Ray Microscope
Journal of Physics: Conf.Series 186 (2009) pp1-3.
2. Gelever V. D. Patent RU № 2 452 052/ Russian/ 27.12.10.3. Gelever V. D. Repin D. S.
Manushkin A. A. Usachev E.Ju. http :// WWW.tntconf.org/2013/ posters.php.?conf=13.
Object- film Re
Fig. 1 X-Ray -projection mode
Fig.2 X-Ray-scanning mode (1detector)
Object- organic film of 270mkm thickness with Zn particles