Electrochemical pore etching in III-V compounds

Pore formation in III-Vs provides for fascinating cross-disciplinary research. The main findings from the present work are: Current line oriented pores; Crystallographically oriented pores grow only along directions; Crystallographic pores promote the formation of unique pore domains; In InP, a self-organized single crystalline pore array was obtained; Well defined Bragg mirrors could be made; Voltage oscillations in the pore formation regime were observed; It was demonstrated, that crystallographic pores can intersect; It was shown that 3D structures can be obtained by the intersection of pores; Tetrahedron-like pores in GaAs have been observed; Integrated waveguide structures have been proposed; The first cathodoluminescence comparison between porous GaP and InP was made. A fundamental understanding of the underlying basic electrochemistry as well as the interactions between pores is very important. Concrete applications of porous III-Vs have to wait for more work in this area of research, but are certainly feasible based on the findings obtained so far

Self-organized pore formation and open-loop-control in semiconductor etching

Electrochemical etching of semiconductors, apart from many technical applications, provides an interesting experimental setup for self-organized structure formation capable e.g. of regular, diameter-modulated, and branching pores. The underlying dynamical processes governing current transfer and structure formation are described by the Current-Burst-Model: all dissolution processes are assumed to occur inhomogeneously in time and space as a Current Burst (CB); the properties and interactions between CB's are described by a number of material- and chemistry- dependent ingredients, like passivation and aging of surfaces in different crystallographic orientations, giving a qualitative understanding of resulting pore morphologies. These morphologies cannot be influenced only by the current, by chemical, material and other etching conditions, but also by an open-loop control, triggering the time scale given by the oxide dissolution time. With this method, under conditions where only branching pores occur, the additional signal hinders side pore formation resulting in regular pores with modulated diameter

Room temperature bonding for vacuum applications: Climatic and long time tests

A detailed and quantitative motivation for the necessity of room temperature (RT) bonding for wafer level packaging of silicon micro-mirrors will be given. Results on RT 6 inch wafer bonding with vacuum encapsulation on test structures are presented. Structured as well as unstructured wafers have been bonded at RT using a Mitsubishi Heavy Industries bonder. Unstructured wafers were used for the determination of the bonding strength, whereas the structured wafers were used for the evaluation of vacuum level and its stability with time

Wafer level vacuum packaging of scanning micro-mirrors using glass-frit and anodic bonding methods

In this paper the authors report about the six inch wafer level vacuum packaging of electro-statically driven two dimensional micro-mirrors. The packaging was done by means of two types of wafer bonding methods: anodic and glass frit. The resulting chips after dicing are 4 mm wide, 6 mm long and 1.6 mm high and the residual pressure inside the package after dicing was estimated to be between 2 and 20 mbar. This allowed us to reduce the driving voltage of the micro-mirrors by more than 40% compared to the driving voltage without vacuum packaging. The vacuum stability after 5 months was verified by measurement using the so called "membrane method". Persistence of the vacuum was proven. No getter materials were used for packaging

MEMS-Wandler zum Interagieren mit einem Volumenstrom eines Fluids und Verfahren zum Herstellen desselben

Ein MEMS-Wandler zum Interagieren mit einem Volumenstrom eines Fluids umfasst eine Substrat, das eine Kavität aufweist und einen elektromechanischen Wandler, der in der Kavität mit dem Substrat verbunden ist und ein sich entlang einer lateralen Bewegungsrichtung verformbares Element aufweist, wobei eine Verformung des verformbaren Elements entlang der lateralen Bewegungsrichtung und der Volumenstrom des Fluids kausal zusammenhängen

Mikromechanische Vorrichtung mit einem aktiv biegbaren Element

Es werden mikromechanische Vorrichtungen beschrieben, die ein aktiv biegbares Element aufweisen. Die Aktivierung wird durch einen Schichtstapel vorgenommen, der die Biegung ansprechend darauf, dass Anziehungskräfte auf die Schichten des Schichtstapels einwirken, bewirkt