Bulk acoustic wave device and method of making such a device
AssigneeCommissariat A L'energie Atomique Et Aux Energies Alternatives
InventorsFlorian Dupont, Guillaume Rodriguez
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Abstract
An electroacoustic device includes, stacked in a direction a silicon-based substrate, a first electrode, a piezoelectric layer with the basis of a perovskite taken from among lithium niobate LiNbO3, lithium tantalum LiTaO3, or an Li(Nb,Ta)O3 alloy, on the first electrode, a second electrode disposed on the piezoelectric layer. Advantageously, the first electrode is made of a nitride-based electrically conductive refractory material, such as TiN, VN, TaN. The invention also relates to a method for producing such a device.
Claims11
A method for producing an electroacoustic device comprising a piezoelectric layer, said electroacoustic device being a bulk acoustic wave filter guided on a Bragg reflector, said method comprising:
- providing a silicon-based substrate,
- forming a first electrode on the substrate,
- forming the piezoelectric layer on the first electrode, and
- forming a second electrode on the piezoelectric layer,
- wherein the first electrode is made of a nitride-based electrically conductive refractory material, and wherein the formation of the piezoelectric layer is done by epitaxy, on said first electrode, of an ABO3-type material, O being oxygen, A being at least one first chemical element taken from among sodium (Na), potassium (K), barium (Ba), lithium (Li), lead (Pb), and B being at least one second chemical element taken from among zirconium (Zr), titanium (Ti), niobium (Nb), tantalum (Ta),
- said method further comprising, before formation of the first electrode, forming a stack of layers alternatively having high and low acoustic impedances, the low impedance layers being TiN- or VN-based, and the high impedance layers being HfN-or TaN-based.
An electroacoustic device comprising, stacked in a vertical direction, a silicon-based substrate, a first electrode on said substrate, a piezoelectric layer epitaxially grown on said first electrode, said piezoelectric layer being with the basis of an ABO3-type material, O being oxygen, A being at least one first chemical element taken from among sodium (Na), potassium (K), barium (Ba), lithium (Li), lead (Pb), and B being at least one second chemical element taken from among zirconium (Zr), titanium (Ti), niobium (Nb), tantalum (Ta), a second electrode disposed on the piezoelectric layer,
- wherein the first electrode is made of a nitride-based electrically conductive refractory material, and
- said electroacoustic device is a bulk acoustic wave filter guided on a Bragg reflector, comprising, between the substrate and the first electrode, a stack of layers alternatively having high and low acoustic impedances, the low impedance layers being TiN-or VN-based, and the high impedance layers being HfN- or TaN-based.
Dependencies are inferred from the claim text.