An electrostatically excited 2D-Micro-Scanning-Mirror with an in-plane configuration of the driving electrodes

A novel resonantly excited 2D-Micro-Scanning-Mirror is presented which makes use of an electrostatic driving principle allowing to locate the driving electrodes in the chip plane. The mechanical elements and the mirror plate consist of a 30 mu m thick single crystal silicon layer. The mirror plate is suspended by a gimbal mounting and can therefore be deflected along two axes. It is shown that a special isolation technique is suitable to seperate the electrical potentials on the movable elements and therfore allows to exite the two oscillations independently. The isolation technique is based on the oxidation and polysilicon filling of 1 mu m wide trenches in the 30 µm thick layer of silicon. The influence of the surrounding gas on the coupling of the oscillations is examined. No significant influence is observed. The performance of the novel 2D-Micro-Scanning-Mirror is demonstrated by the generation of various Lissajous patterns by the reflectes laser beam. Freqency ratios of 1:1 up to 13:1 are obtained with the presented devices.