Thermally actuated optical microscanner with large angle and low consumption

A monolithic silicon integrated optical micro-scanner is presented. The dev ice consists of a mirror located on the tip of a thermal bimorph actuator b eam. The fabrication process is very simple and compatible with IC fabricat ion techniques. The device is excited electrothermally at its resonance fre quency, enabling large angular deflections at low power consumption. The te chnological process consists of basic frontside silicon micromachining step s requiring only three mask levels. The moving part is defined by selective silicon bulk etching. The bimorph beam is made of silicon dioxide and a th in film conductor. The residual stress in the two layers is used to achieve a 45 degrees out-of-plane rest position of the mirror. This allows optical components (e.g., laser diode, collimating lens) to be placed directly on the silicon substrate. Mirrors of 500 x 300 to 800 x 800 mu m(2) with reson ant frequencies varying from 600 to 100 Hz were realized. Mechanical scan a ngles of above 90 degrees were achieved. The devices are very robust and ha ve run through fatigue tests of billions of cycles at 300 Hz and 90 degrees deflection. The power consumption of the device is typically 1 mW for 30 d egrees mirror deflection. (C) 1999 Elsevier Science S.A. All rights reserve d.