Thick glass film technology for polysilicon surface micromachining

This paper explores the use of thick glass films as suitable alternatives to CVD oxide films for use as sacrificial, planarization, and passivation layers in polysilicon surface micro-machining processes. Such glasses can be spin-coated to produce films up to 20 μm thick in one step and to globally planarize the wafer surface, extending the overall mechanical design capability by enabling additional device structural complexity. Glass optical constants were determined, and the film quality was evaluated using SEM, EDS, XPS, and XRD. The films were found to have low intrinsic stresses and other characteristics desirable for sacrificial layer applications. A glass chemical-mechanical polishing process with 5300~Å/min removal rate and acceptable selectivity to polysilicon was developed, along with a wet etch chemistry that preferentially etches the film at 3.24 μm/min without affecting the silicon substrate or the structural polysilicon. The film was used to planarize up to 10-μm-tall topographies associated with surface micromachined features through spin-on and polish-back steps, and was in addition demonstrated to be a viable protective layer for silicon wafers during extended KOH etching in silicon bulk micro-machining processes. The glass has stable constituents that do not diffuse or contaminate either the substrate or the device features during the application and firing procedures     

A rotary electrostatic micromotor 1×8 optical switch

This paper describes a 1×8 rotary electrostatic micromotor optical switch fabricated using high-aspect-ratio micromachining technology to produce silicon or nickel components which are subsequently assembled to form a switch. The switch consists of a salient-pole micromotor with 1-mm-diameter 200-μm-thick rotor that supports up to a 500-μm-tall, 900-μm-wide mirror. Typical switches were actuated at 50 V, operated for extended periods in room air, and found to have a rapid rotation with an average optical switching time between two neighboring fiber ports of 18 ms. Optical testing was performed at wavelength of 1310 nm in single- and multimode, and at 850 nm in multimode. The optical beam was propagated in free space with minimal divergence through the use of externally mounted collimating gradient-index lenses. With an aluminum coating, the mirror and external optics exhibited an input to output coupling loss as low as 0.96 dB in multimode and 2.32 dB in single-mode. Interchannel crosstalk was less than -45 dB     

Characterization of native and adsorbed thin films on silicon detector surfaces: static and kinetic applications

The photoelectric response of a windowless reflective silicon photodetector for obliquely incident polarized monochromatic light is used to characterize the native passivation dielectric thin film at the detector surface. In the presence of adsorption, the generated photoelectric signal becomes a function of the thickness and refractive index of the adsorbed layer. Higher sensitivity is achieved with s-polarized light and at incidence angles> 60 °. Furthermore, the passivation layer can be optimized for a specific adsorption experiment. A sensor of this kind is used to study the adsorption kinetics of H₂O at the detector surface and the results are interpreted by Bruggeman's effective medium theory. If a second detector is introduced to intercept the light reflected by the first detector, and the polarization of the incident light is modulated, analysis of output signals of this two-detector system determines the responsivity, absolute reflectances, and ellipsometric parameters of the first detector surface.     

Using a language independent domain model for multilingual information extraction

The volume of electronic text in different languages, particularly on the World Wide Web, is growing significantly, and the problem of users who are restricted in the number of languages they read obtaining information from this text is becoming more widespread. This article investigates some of the issues involved in achieving multilingual information extraction (IE), describes the approach adopted in the M-LaSIE-II IE system, which addresses these problems, and presents the results of evaluating the approach against a small parallel corpus of English/French newswire texts. The approach is based on the assumption that it is possible to construct a language independent representation of concepts relevant to the domain, at least for the small well-defined domains typical of IE tasks, allowing multilingual IE to be successfully carried out without requiring full machine translation.     

Common weaving approach in mainstream languages for software security hardening

In this paper, we propose a novel aspect-oriented approach based on GIMPLE, a language-independent and a tree-based representation generated by the GNU Compiler Collection (GCC), for the systemization of application security hardening. The security solutions are woven into GIMPLE representations in a systematic way, eliminating the need for manual hardening that might generate a considerable number of errors. To achieve this goal, we present a formal specification for GIMPLE weaving and the implementation strategies of the proposed weaving semantics. Syntax for a common aspect-oriented language that is abstract and multi-language support together with syntax for a core set for GIMPLE constructs are presented to express the weaving semantics. GIMPLE weaving accompanied by a common aspect-oriented language (1) allows security experts providing security solutions using this common language, (2) lets developers focus on the main functionality of programs by relieving them from the burden of security issues, (3) unifies the matching and the weaving processes for mainstream languages, and (4) facilitates introducing new security features in AOP languages. We handle the correctness and the completeness of GIMPLE weaving in two different ways. In the first approach, we prove them according to the rules and algorithms provided in this paper. In the second approach, we accommodate Kniesel's discipline that ensures that security solutions specified by our approach are applied at all and only the required points in source code, taking into consideration weaving interactions and interferences. Finally, we explore the viability and the relevance of our propositions by applying the defined approach for systematic security hardening to develop case studies.     

The plastic zones and displacements around underground openings in rock masses containing a fault

Faults are the commonly encountered large geological discontinuities in hard rock masses, most severe underground structure instability is found to be closely associated with the faults presence nearby. The parametric study carried out in this paper using numerical method (UDEC) has identified some fault parameters to be really critical for the underground structure stability. These fault parameters are fault dips, fault shear strength and fault locations relative to the underground structure. This numerical investigation revealed that faults affect the stability of underground structure by the tendency of increasing the plastic zones, displacements and causing both asymmetrically distributed in the rock masses adjacent to the excavation. The relationship of the induced plastic zones, maximum displacements varying with these fault parameters was established. The distribution of plastic zone and displacement was graphically presented and the mechanisms such effects were discussed. These results offer a guideline in support design.