Optical spectroscopy as a monitor of thin film growth in sputtering

Abstract

ABSTRACT Line intensity ratio has been used in astronomy to calculate plasma density and temperature. This procedureis applied to monitor thin “lm growth in plasma-assisted deposition, it provides very useful information such asdensity and temperature of the plasma. The propose of this study is monitor variations of the plasma duringdeposition, using wide “eld optical spectroscopy and establish a relation with thin “lm stoichiometry. We reportthe preparation of inhomogeneous SiO x N y thin “lms, by sputtering. 1. INTRODUCTION Thin “lms have several applications, a major one is optical interference coatings, which have a wide impactin science and technology since 1940. Pa rticularly, the use of reactive depos ition opens the possibility for newmaterials, like rugate “lters or inhomogeneous “lms, which provide a versatile technique to adapt nearly everytransmittance to an index pro“le. 1–3 In theory, inhomogeneous thin “lms are ”exible and powerful, but realdeposition had to wait 20 years until it became feasible to be built them.Die rent techniques are used to coat inhomogeneous “lms. Co-evaporation technique is complicated, becausetwo deposition sources are placed simultaneously inside the chamber, expecting the “lm to incorporate properlymixed material. The reactive deposition, though dic ult to perform, is easier to handle: one material source isplaced inside the chamber, while a rea ctive gas is carefully introduced, rea cting with the evaporated species.Sputtering technique, widely used in electronics industry, until recent years enter the mainstream of opti-cal thin “lm deposition.