# US 11,451,211 B2 · Gallium nitride structure, piezoelectric element, method of manufacturing piezoelectric element, and resonator using piezoelectric element > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,451,211 B2 - Document ID: US11451211B2 - Status: Granted - Kind: B2 - Application number: 16/126,248 - Filed: 2018-09-10 - Published: 2019-01-03 - Granted: 2022-09-20 - Earliest claimed: 2016-03-11 - Assignees: Murata Manufacturing Co., Ltd.; National Institute of Advanced Industrial Science and Technology - Applicants: Murata Manufacturing Co., Ltd.; National Institute of Advanced Industrial Science and Technology - Inventors: Keiichi Umeda; Takaaki Mizuno; Yasuhiro Aida; Masato Uehara; Toshimi Nagase; Morito Akiyama - Web page: https://patentgrep.com/patent/US11451211B2 ## CPC - H03H 9/176: {consisting of ceramic material (H03H9/177, H03H9/178 take precedence)} - H03H 3/02: for the manufacture of piezoelectric or electrostrictive resonators or networks (H03H3/08 takes precedence) - H03H 9/0595: {the holder support and resonator being formed in one body} - H03H 9/131: {consisting of a multilayered structure} - H10N 30/06: Forming electrodes or interconnections, e.g. leads or terminals - H10N 30/076: by vapour phase deposition - H10N 30/704: {based on piezoelectric or electrostrictive films or coatings} - H10N 30/853: Ceramic compositions - H10N 30/877: {Conductive materials} - H03H 2003/027: {the resonators or networks being of the microelectro-mechanical [MEMS] type} - H03H 2009/02488: {Vibration modes} - H03H 2009/155: {using MEMS techniques} - H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P) - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR ## Abstract A gallium nitride structure that includes: a substrate; a gallium nitride layer opposed to the substrate and containing gallium nitride as a main component thereof; and a first electrode between the gallium nitride layer and the substrate. The first electrode includes at least one hafnium layer containing a single metal of hafnium as a main component thereof, and the at least one hafnium layer is in contact with the gallium nitride layer. ## Claims ### Claim 1 A gallium nitride structure, comprising: a substrate; a gallium nitride layer provided so as to be opposed to the substrate and containing gallium nitride as a main component; and a first electrode that is provided between the gallium nitride layer and the substrate, the first electrode including at least one hafnium layer containing a single metal of hafnium as a main component thereof, and the at least one hafnium layer in contact with the gallium nitride layer. ### Claim 2 A gallium nitride structure, comprising: a substrate; a gallium nitride layer provided so as to be opposed to the substrate and containing gallium nitride as a main component; and a first electrode that is provided between the gallium nitride layer and the substrate, the first electrode including at least one hafnium layer containing hafnium as a main component thereof the at least one hafnium layer in contact with the gallium nitride layer, wherein the at least one hafnium layer includes: a first hafnium layer that is in contact with the substrate; a second hafnium layer that is in contact with the gallium nitride layer; and a metal layer having a resistivity lower than hafnium between the first hafnium layer and the second hafnium layer. ### Claim 3 (depends on 2) The gallium nitride structure according to claim 2, wherein the metal layer is an aluminum layer containing aluminum as a main component thereof. ### Claim 4 (depends on 2) The gallium nitride structure according to claim 2, further comprising a second electrode opposed to the first electrode with the gallium nitride layer therebetween. ### Claim 5 (depends on 1) The gallium nitride structure according to claim 1, further comprising a second electrode opposed to the first electrode with the gallium nitride layer therebetween. ### Claim 6 (depends on 1) The gallium nitride structure according to claim 1, wherein the substrate comprises a degenerated n-type Si. ### Claim 7 (depends on 1) A resonator comprising: a vibration portion comprising the gallium nitride structure according to claim 1; a holding portion surrounding the vibration portion; and a holding arm connecting the vibration portion to the holding portion. ### Claim 8 (depends on 2) A resonator comprising: a vibration portion comprising the gallium nitride structure according to claim 2; a holding portion surrounding the vibration portion; and a holding arm connecting the vibration portion to the holding portion. ### Claim 9 (depends on 8) The resonator according to claim 8, wherein the metal layer is an aluminum layer containing aluminum as a main component thereof. ### Claim 10 (depends on 8) The resonator according to claim 8, further comprising a second electrode opposed to the first electrode with the gallium nitride layer therebetween. ### Claim 11 (depends on 7) The resonator according to claim 7, further comprising a second electrode opposed to the first electrode with the gallium nitride layer therebetween. ### Claim 12 (depends on 7) The resonator according to claim 7, wherein the substrate comprises a degenerated n-type Si. ### Claim 13 A method of manufacturing a piezoelectric element, the method comprising: forming a first electrode including a hafnium layer containing a single metal of hafnium as a main component thereof on a substrate by sputtering; and forming a piezoelectric body layer containing gallium nitride as a main component thereof on the first electrode by sputtering. ### Claim 14 (depends on 13) The method of manufacturing a piezoelectric element according to claim 13, wherein the piezoelectric body layer is formed at a temperature of 500° C. ### Claim 15 (depends on 13) The method of manufacturing a piezoelectric element according to claim 13, wherein the forming of the first electrode includes: forming a first hafnium layer on the substrate; forming a metal layer having a resistivity lower than hafnium on the first hafnium layer; and forming a second hafnium layer on the metal layer. ### Claim 16 (depends on 15) The method of manufacturing a piezoelectric element according to claim 15, wherein the metal layer is an aluminum layer containing aluminum as a main component thereof. ### Claim 17 (depends on 15) The method of manufacturing a piezoelectric element according to claim 15, further comprising forming a second electrode on the piezoelectric body layer. ### Claim 18 (depends on 13) The method of manufacturing a piezoelectric element according to claim 13, further comprising forming a second electrode on the piezoelectric body layer. ### Claim 19 (depends on 13) The method of manufacturing a piezoelectric element according to claim 13, wherein the substrate comprises a degenerated n-type Si.