Fabrication of x-ray zone plates by surface-plasma chemical vapor deposition

Abstract

A new cost-efficient sputter-slice technology for hard x-ray (10-30 keV) Fresnel zone plates fabrication, imposing no limitation to aspect ratio, is proposed. By means of a plasma chemical process, SiO(2)/Si(1-x)Ge(x)O(2) glassy film multilayer structures are deposited on a lateral surface of a silica rod, outermost layers being as thin as 100 nm. It has been shown by numerical simulation that for x=0.2 germanium fraction, 100-300 microm zone plate thickness and the number of zones of about 1000, first order diffraction efficiency as high as 20%-30% at the energy of approximately 20 keV can be achieved.

Multilagenzonenplatten für die Mikroskopie mit harter Röntgenstrahlung

“…Multilagenbeschichtungen mittels plasmagestützter chemischer Gasphasenabscheidung (engl. surface-plasma chemical vapor deposition, SPCVD) führten aufgrund der sehr hohen Depositionsraten dagegen noch zu keinen Zonenbreiten unterhalb von 100 nm [113] und können daher eher als preiswerte Kondensorlinsen für harte Röntgenstrahlung gesehen werden [114].…”

Zone plates for hard X-rays fabricated with the SPCVD technology

“…[11]). It is capable of producing optical fibers consisting of alternating layers of silica and germanium glasses: SiO 2 and (SiO 2 ) 1Àx (GeO 2 ) x or, alternatively, silica and tin glasses: SiO 2 and (SiO 2 ) 1Àx (SnO 2 ) x .…”

“…The parameter x can be as high as 0.2 [11]. These materials have refraction indexes and absorption coefficients that are significantly different in the hard X-ray part of the spectrum.…”

“…The slicing of an optical fiber makes mass production of zone plates possible-the thickness of a FZP is usually 0.1-0.3 mm, whereas the length of the fiber can reach many meters. Thus the FZP's produced in this way will be significantly cheaper than those made with lithography [11]. The ultimate spatial resolution, which can be attained with such fiber optical zone plates (FOZP), is about 0.1 mm.…”

Silica-based films and multilayer stacks for lightwave circuits fabricated by surface-plasma chemical vapor deposition

“…An example of a practical application of such process is the fabrication of Fresnel zone plates intended for hard x-rays focusing [9]. Zone plates in this technology are fabricated by perpendicular slicing the filament together with deposited on its lateral surface film structure.…”