MEMS piezoelectric switch
View Patent ↗The present invention provides a MEMS piezoelectric switch that has an articulated unimorph bridge attached to a substrate. The bridge includes a passive layer of zirconia and at least one silicon-based material, an active layer of a piezoelectric material that has a high piezoelectric coefficient, at least one pair of interdigitated electrodes, disposed on the top surface of the active layer and across which the bias voltage is applied, and a top contact electrode. A bottom contact electrode is provided on the substrate, and signals flow through the switch when the top and bottom contact electrodes contact one another.
1. A microelectromechanical systems (MEMS) piezoelectric switch, comprising:
a substrate having a bottom contact electrode disposed on an upper surface; and
an articulated unimorph bridge, having first and second ends attached to the substrate, including:
a passive layer including zirconia and at least one silicon-based material,
an active layer, disposed on an upper surface of the passive layer, including a piezoelectric material having a high piezoelectric coefficient,
at least one pair of interdigitated electrodes, disposed on an upper surface of the active layer, across which a bias voltage is applied, and
a top contact electrode that contacts the bottom contact electrode when the bridge is in a first position, and that does not contact the bottom contact electrode when the bridge is in a second position;
wherein the interdigitated electrodes form an interleaved, circular pattern surrounding the top contact electrode.
2. The MEMS piezoelectric switch of claim 1 , wherein the piezoelectric material is PZT and the silicon-based material is silicon nitride or silicon dioxide.
3. The MEMS piezoelectric switch of claim 1 , wherein the switch is a normally-open switch, the bridge moves to the first position when a positive bias voltage is applied to the interdigitated electrodes, and the bridge moves to the second position when a zero bias voltage is applied to the interdigitated electrodes.
4. The MEMS piezoelectric switch of claim 3 , wherein the positive bias voltage is at least 5 V.
5. The MEMS piezoelectric switch of claim 1 , wherein the width of each interdigitated electrode finger is about 5 μm and the separation between each opposing interdigitated electrode finger is about 5 μm.
6. The MEMS piezoelectric switch of claim 1 , wherein the top contact electrode is surrounded by the active layer.
7. The MEMS piezoelectric switch of claim 1 , wherein interdigitated electrodes are arranged concentrically about the top contact electrode.