Millimeter length micromachining using a heavy ion nuclear microprobe with standard magnetic scanning

Abstract

In order to increase the scanning length of our microprobe, we have developed an irradiation procedure suitable for use in any nuclear microprobe, extending at least up to 400% the length of our heavy ion direct writing facility using standard magnetic exploration. Although this method is limited to patterns of a few millimeters in only one direction, it is useful for the manufacture of curved waveguides, optical devices such Mach-Zehnder modulators, directional couplers as well as channels for micro-fluidic applications. As an example, this technique was applied to the fabrication of 3mm 3D-Mach-Zehnder modulators in lithium niobate with short Y input/output branches and long shaped parallel-capacitor control electrodes. To extend and improve the quality of the machined structures we developed new scanning control software in LabView TM platform. The new code supports an external dose normalization, electrostatic beam blanking and is capable of scanning figures at 16 bit resolution using a National Instruments TM PCI-6731 High-Speed I/O card. A deep and vertical micromachining process using swift 35 Cl ions 70 MeV bombarding energy and direct write patterning was performed on LiNbO 3 , a material which exhibits a strong natural anisotropy to conventional etching. The micromachined structures show the feasibility of this method for manufacturing micro-fluidic channels as well.

Experimental Setup of the Fast Current Controller for the Buenos Aires Heavy Ion Microbeam

“…Previous studies [1] show that using fluences of 5 × 10 12 ions/cm 2 of Cl 35 at 70 MeV generate lattice damage in a way that the etching rate in an HF (50%) acid increases drastically. We used a similar projectile as in [4,5], a 5 µm beam spot of 32 S 8+ at 75 MeV energy and 250 × 250 µm 2 scanned area. The electrostatic deflector was used to reduce the flux using a pulse width modulation (PWM) signal phased with a triangular (sawtooth) signal.…”

“…It is one of the experimental lines of the Tandar 20UD Pelletron accelerator and comprises Oxford Microbeams Ltd. (Oxfordshire, UK) OM55 triplet of magnetic quadrupoles. It was originally set up for micro-PIXE (micro-particle induced X-Ray emission) [1][2][3] elemental analysis and micromachining [4,5]. Recently, it was employed in SEE (single event effects) testing, IBIC/TRIBIC (ion beam induced charge/time-resolved IBIC) measurements and total dose studies of semiconductors [6].…”