Low energy ion modification of thin films

Abstract

This paper presents some of the uses of broad beams of low energy (< 500 eV) ions for modifying surfaces and thin films physically and chemically. We discuss bombardment-induced variation in the index of refraction of thin films with applications in integrated optics, variation of etch profiles using biased masks, and generation of heavy ion beams. ZrO x F y films were made by depositing ZrF 4 with a coincident oxygen ion flux. The index of refraction can be increased by 0.12 without increasing waveguide losses beyond 8 dB/cm, with ion energy being the primary determinant of index variation, and ion flux having the largest effect on losses. The second modification technique focuses on the use of local fields at the substrate to alter the path of incoming ions. Using voltage biased metal masks, we have been able to alter the sputter-etch profile of thin films. The experimental results are compared with calculated etch profiles; changes in the etch angle of up to 20° have been observed. We describe preliminary work on the generation and use of C 60 and metal ions as bombarding particles.