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This study presents an investigation of the adhesion properties of a chromium-gold-titanium layer system, which is used in the LIGA process to create moveable microstructures. The main purpose has been the improvement of the process parameters to increase yield reliability. Three mechanisms affecting the adhesion have been identified. As a consequence of humidity adsorbed H2O reacts with Al2O3 to AlO(OH) (aluminum meta hydrates), which does not bond to the sputtered chromium layer. Thus the hydrate must be removed by cleaning the surface with Ar+-ions. Tight layers without pores could be realized by optimization pressure and temperature during sputtering of chromium and gold. Thus, diffusion of chromium or penetration of etchants into the gold layer as well as impact or diffusion of titanium into the gold layer could be prevented. In addition, a copper layer was introduced as a further intermediate layer by electroforming to improve the formation of stable nickel alloys at the interface between the sputtered gold and the electroplated nickel. These measures resulted in an improvement of the adhesion, so that full functional acceleration sensors were produced with a high yield. [ABSTRACT FROM AUTHOR]

Abstract. The growing field of microtechnology creates a need for new methods of structuring affordable materials. Excimer ablation lithography (EAL) has been introduced as a new method for producing microstructures. The ablation and microstructuring behavior of bis-phenol-polycarbonate-A, several polyestercarbonates and their blends in varying proportions, were investigated by using the radiation of a XeCl excimer laser. It was found that a minimum content of polyester, either in the co-condensate or in the blend, is necessary to obtain transparent structures in the irradiated film for irradiation at 308 nm. When recorded as a function of the molar fraction of the polyester, the etch rate passes through a local maximum and consecutively decreases with increasing content of the polyester group in the polymer bulk. Microstructures with a resolution in the sub-micron scale were obtained by EAL, and the resultant structures were made visible and analyzed using an atomic force microscope (AFM). [ABSTRACT FROM AUTHOR]

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