It has been reported that surface roughening is an effective approach to developing microtextures for high performance magnetic media, increased adherence of coatings on large thermal expansion coefficient mismatched substrates as well as enhanced surface coupling for photodetectors. An important prerequisite is that the controllable and reproducible pattern ought to be produced while minimum adverse effects result on materials. In this study, a novel interface ripple pattern is generated on the surface of the single crystal silicon coated with a thin silicon dioxide layer using a KrF excimer laser at different laser parameters. Experimental result show that the ripple period cannot be predicted by the Rayleigh's diffraction condition as conventional laser induced periodic surface structures on solids. The ripple pattern is firstly seeded at the interface and the tin film capping laser will yield ripple structures following the interface rippling. The amount of absorbed KrF laser energy by the SiO₂/Si interface is identified to have little dependence on film thickness. Within a certain range of laser parameters, ripple pattern grown with laser fluence or number of pulse linearly rather than exponentially. Of particular interest is that ripple period has been found to have a linear dependence on the film thickness at given laser parameters. This controllable ripple pattern provides a sound solution to the cases that require low laser fluence to prevent materials from damage or demand interface roughening which cannot be achieved by conventional techniques. The uniformity of ripple structures can be controlled by properly adjusting the laser parameters between melting and ablation thresholds and the single crystallinity of the Si substrate remains unchanged under laser irradiation at the fluence up to 1.3 J/cm².

Date Published: 4 November 1999
PDF: 11 pages
Proc. SPIE 3898, Photonic Systems and Applications in Defense and Manufacturing, (4 November 1999); doi: 10.1117/12.368486

Published in SPIE Proceedings Vol. 3898:
Photonic Systems and Applications in Defense and Manufacturing
Yee Loy Lam; Koji Ikuta; Metin S. Mangir, Editor(s)