Si-wafer bending technique for a three-dimensional microoptical bench

We propose and demonstrate a Si-wafer bending technique for preparing a three-dimensional microoptical bench (MOB). The process for preparing the three-dimensional MOB is based on the usual planar photolithography, anisotropic wet etching and preparation of the photoresist V-groove joint, The bending angle is controlled by the jig on which the wafer is fixed. This jig is prepared separately by the usual machining. The measured accuracy of the bending angle is within ±0.2°. The advantage of this method is that an arbitrary bending angle can be set by changing the jig without the restriction of micromachining. This is a combination of the usual machining technique and the micromachining technique which realizes a three-dimensional microstructure. This simple and flexible bending technique can yield three-dimensional MOBs on which optical elements can be aligned by chip bonding or by preparing an alignment guide.