Abstract
We report on the use of CHF3, C2F6, and SF6 as etch gases for deep reactive ion etch processing of germano-boro-silicate glass films prepared by flame hydrolysis deposition (FHD). The glass film under study had a composition of 83 wt % SiO2, 12 wt % GeO2, and 5 wt % B2O3. The scope of the study was to identify the benefits and drawbacks of each gas for fabrication of deep structures (>10 mu m) and to develop an etch process in each peas system. The etch rate, etch profile, and surface roughness of the FHD glass films were investigated for each gas. Etch rates and surface roughness were measured using a surface profiler and etch profiles were assessed using a scanning electron microscope. It was found that SF6 had the highest FHD glass etch rate and nichrome mask selectivity (>100:1) however, it had the lowest photoresist mask selectivity (<1:2) and highest lateral erosion. CHF3 had the lowest FHD glass etch rate but high selectivity over both nichrome (>80:1) and photoresist (>10:1) and the etch profile was found to be smooth and vertical. C2F6 had a similar etch profile to that of CHF3, but the selectivity over both mask materials was lower than in CHF3. Fused silica was used as a reference material where it was found the percentage drop in etch rate in C2F6, SF6, and CHF3 was -12%, -15%, and -37%, respectively. From the results presented here CHF3 proved to be the most versatile etch process as either photoresist or nichrome masks could be used to attain depths of 20 mu m, or more. (C) 1998 American Vacuum Society.

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Abstract
Fluorescence lifetimes and scatter losses for Er3+ doped, silica waveguides formed by aerosol doping and flame hydrolysis deposition are reported. The fast decay component and out of plane scatter decreased markedly with optimisation of the deposition technique, sintering process and co-doping regime. (C) 1998 Elsevier Science B.V.

Abstract

Abstract
In this paper we argue that using verification in interactive systems development is more than just checking whether the specification of the system has all the required properties; and that changing the focus from a global specification into partial, property oriented, specifications can provide a number of advantages and make verification act as an aid to decision making. We also present a compiler that allows for the verification of interactor specifications to be done in SMV, as well as a simple case study where verification is used to inform a design decision.

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