This work investigates the isotropic etching properties of an inductively coupled plasma (ICP) etcher for masked and maskless etching steps in reference to fabrication of a silicon microlens mold. Using the described method a wide range of lens geometries and lens arrays with 100% fill factor can be achieved. The silicon etching is performed with a continuous SF6 based ICP. Analysis of the etching profile was done by SEM inspection and by optical interferometric measurements. For the masked etching step a consistent picture of the profile evolution is obtained, including a relation between the etching depth, the radius of curvature of the profile, the etching time and the size of the mask opening. For the maskless etching step, the optimal etch is purely isotropic. Within the tested process parameter range the maskless etching showed a non-isotropic behavior, which results in lens aberrations, crystal orientation dependence, poor uniformity and roughness. Generally a trade-off between the individual etching behaviors is found, but useful etching recipes can be found for a range of different lens geometries.

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In-situ fatigue test devices with integrated electrostatic actuator were fabricated in electroplated nanocrystalline nickel (nano-nickel) . The devices feature in-plane approximately pure bending with fixed displacement of the test specimen of the dimensions: widths from 2pm to 3.7pm, a height of 7pm and an effective length from 4pm to 27pm. Maximum stresses of the test beam were calculated to be 500MPa to 2100MPa by use of FEM tools. The test results indicate very promising fatigue properties of nano-nickel, as none of the test devices have shown fatigue failure or even initiation of cracks after lo8 cycles. The combination of high strength and toughness, which is known for nanocrystalline materials, together with very small test specimens and low surface roughness could be the explanation for the good fatigue properties.