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US 7,463,118 B2Granted
Piezoelectric resonator with an efficient all-dielectric Bragg reflector
AssigneeTexas Instruments Incorporated
InventorStuart M. Jacobsen
Life of this patent
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Abstract
A piezoelectric resonator with an acoustic Bragg reflector that includes alternating layers of high and low acoustic impedance materials. The high and low acoustic impedance dielectric materials make up electrically insulating layers.
Claims16
A resonator apparatus, comprising:
- a piezoelectric resonator;
- and
- an acoustic Bragg reflector underlying the piezoelectric resonator;
- the acoustic Bragg reflector comprising a plurality of dielectric layers disposed directly on one another, where a first of the dielectric layers comprises a high acoustic impedance material, and a second of the dielectric layers abuts the first dielectric layer and comprises a low acoustic impedance material,
- wherein the high acoustic impedance material comprises at least one of the following three types of material:
- silicon carbon (SiC), diamond-like carbon (DLC), and silicone doped diamond-like carbon (Si-DLC).
3 more elements
A method of forming a piezoelectric resonator with a Bragg reflector, the method comprising:
- depositing a dielectric layer of low acoustic impedance material over a substrate, the low acoustic impedance material comprising at least one of the following materials:
- nano-porous methyl silsesquioxane (MSQ), nano-porous hydrogensilsesquioxane (HSQ), nano-porous mixtures of MSQ and HSQ, nanoglass, aerogel, spin-on-glasses (SOG) with the addition of pores in the final film, and spin-on siloxane monomers with additives to promote the formation of pores;
- depositing a dielectric layer of high acoustic impedance material over the substrate;
- depositing alternating dielectric layers of the low acoustic impedance material and the high acoustic impedance material until the Bragg reflector meets the required reflectivity;
- depositing a first resonator electrode;
- depositing a piezoelectric layer;
- and
- depositing a second resonator electrode.
5 more elements
A method of forming a piezoelectric resonator with a Bragg reflector, the method comprising:
- depositing a dielectric layer of low acoustic impedance material over a substrate;
- depositing a dielectric layer of high acoustic impedance material over the substrate, wherein the high acoustic impedance material comprises at least one of the following:
- silicon carbon (SiC), diamond-like carbon (DLC), silicone doped diamond-like carbon (Si-DLC);
- depositing alternating dielectric layers of the low acoustic impedance materials and the high acoustic impedance materials until the Bragg reflector meets the required reflectivity;
- depositing a first resonator electrode;
- depositing a piezoelectric layer;
- and
- depositing a second resonator electrode;
- wherein the layer of high acoustic impedance material is deposited in a 150 mm parallel plate reactor RFCVD chamber with an upper plate being the gas distribution source and a lower plate being the cathode on which the substrate lies, the RF source of about 13.56 MHz is coupled directly to the substrate through the cathode.
6 more elements
Dependencies are inferred from the claim text.