US-12620966-B2 - Solidly mounted resonator

US12620966B2US 12620966 B2US12620966 B2US 12620966B2US-12620966-B2

Abstract

Provided are a solidly mounted resonator and a method for preparing a solidly mounted resonator. The solidly mounted resonator includes: a piezoelectric structure, wherein the piezoelectric structure includes: an upper electrode layer, a lower electrode layer and a piezoelectric layer. The lower electrode layer disposed corresponding to the piezoelectric structure, and the lower electrode layer includes: a protruding portion protruding downward corresponding to a lower surface of the lower electrode layer; the piezoelectric layer is disposed on an upper surface of the lower electrode layer; the upper electrode layer is disposed on an upper surface of the piezoelectric layer.

Inventors

Wei Wang
Jinming Yang
Ping Li
Jiang Jiang
Bohua PENG
Nianchu Hu
Bin Jia

Assignees

EPICMEMS (XIAMEN) CO., LTD.

Dates

Publication Date: 20260505
Application Date: 20200318

Claims (6)

1 . A solidly mounted resonator, comprising: a piezoelectric structure, wherein the piezoelectric structure comprises: a lower electrode layer disposed corresponding to a lower portion of the piezoelectric structure, wherein the lower electrode layer comprises: a protruding portion protruding downward corresponding to a lower surface of the lower electrode layer; a piezoelectric layer disposed on an upper surface of the lower electrode layer; an upper electrode layer disposed on an upper surface of the piezoelectric layer, a substrate layer disposed below the piezoelectric structure, and a laminated structure disposed between the piezoelectric structure and the substrate layer, wherein the laminated structure sequentially comprises: a first low acoustic impedance layer, a first high acoustic impedance layer, a second low acoustic impedance layer, a second high acoustic impedance layer, and a third low acoustic impedance layer from bottom to top, wherein the third low acoustic impedance layer is disposed below the piezoelectric layer of the piezoelectric structure, wherein the third low acoustic impedance layer comprises: a lower electrode slot recessed downward relative to an upper surface of the third low acoustic impedance layer, wherein the lower electrode slot comprises: a first groove recessed downward corresponding to an edge of a bottom surface of the lower electrode slot; and a second groove recessed downward corresponding to a middle portion of the bottom surface of the lower electrode slot.
2 . The solidly mounted resonator according to claim 1 , wherein the protruding portion comprises: a first protruding portion protruding downward corresponding to an edge of the lower surface of the lower electrode layer; and a second protruding portion protruding downward corresponding to a middle portion of the lower surface of the lower electrode layer.
3 . The solidly mounted resonator according to claim 2 , wherein the first protruding portion is an annular closed structure; wherein a distance between an inner edge of the first protruding portion and an outer edge of the second protruding portion is a first distance a; a protruding distance of the first protruding portion relative to the lower surface of the lower electrode layer is a second distance b; a protruding distance of the second protruding portion relative to the lower surface of the lower electrode layer is a third distance c; wherein b>c.
4 . The solidly mounted resonator according to claim 1 , wherein, the upper surface of the lower electrode layer is a planarization surface; materials of the upper electrode layer and the lower electrode layer are combinations of one or more materials selected from molybdenum (Mo), titanium (Ti), tungsten (W), gold (Au), aluminum (Al), and platinum (Pt); and a material of the piezoelectric layer is aluminum nitride (AlN), zinc oxide (ZnO) or lead zirconate titanate (PZT).
5 . The solidly mounted resonator according to claim 1 , wherein the first groove is a closed annular slot; wherein a distance between an inner edge of the first groove and an outer edge of the second groove is a first distance a; a concave distance of the first groove relative to the bottom surface of the lower electrode slot is a second distance b; a concave distance of the second groove relative to the bottom surface of the lower electrode slot is a third distance c; wherein b>c.
6 . The solidly mounted resonator according to claim 1 , wherein a material of the substrate layer is a combination of one or more materials selected from silicon, glass, sapphire, and ceramics; materials of the first low acoustic impedance layer, the second low acoustic impedance layer and the third low acoustic impedance layer are siloxane or silicon dioxide; and materials of the first high acoustic impedance layer and the second high acoustic impedance layer are tungsten or molybdenum.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a U.S. National Stage Application of PCT/CN2020/079973, filed 18 Mar. 2020, and which application is incorporated herein by reference. To the extent appropriate, a claim of priority is made to the above disclosed application. TECHNICAL FIELD The present disclosure relates to a field of resonator technology, and in particular, to a solidly mounted resonator and a method for preparing a solidly mounted resonator. BACKGROUND Solidly Mounted Resonator (SMR for short) is a device that includes a Bragg reflector structure and a piezoelectric structure. In an application of a conventional solidly mounted resonator, the piezoelectric structure is formed on the Bragg reflector structure. The Bragg reflector is formed by alternating high and low acoustic impedance materials. The piezoelectric structure is composed of upper and lower electrode layers sandwiching piezoelectric materials. A piezoelectric material may be grown on an upper surface of a lower electrode to form a piezoelectric layer. Therefore, in the related art, a lower electrode pattern is usually etched first and then a piezoelectric layer is deposited, so that the piezoelectric layer may be grown on a surface of an uneven lower electrode, and a lattice structure and lattice orientation of the piezoelectric layer may be deteriorated in an uneven place, thereby affecting a piezoelectric effect and affecting a device performance. SUMMARY One aspect of the present disclosure provides a solidly mounted resonator, including: a piezoelectric structure, wherein the piezoelectric structure includes: a lower electrode layer, a piezoelectric layer, and an upper electrode layer. The lower electrode layer is disposed corresponding to a lower portion of the piezoelectric structure, and the lower electrode layer includes: a protruding portion protruding downward corresponding to a lower surface of the lower electrode layer; the piezoelectric layer is disposed on an upper surface of the lower electrode layer; and the upper electrode layer is disposed on an upper surface of the piezoelectric layer. According to the embodiments of the present disclosure, the protruding portion includes: a first protruding portion and a second protruding portion. The first protruding portion protrudes downward corresponding to an edge of the lower surface of the lower electrode layer; the second protruding portion protrudes downward corresponding to a middle portion of the lower surface of the lower electrode layer. According to the embodiments of the present disclosure, the first protruding portion is an annular closed structure; a distance between an inner edge of the first protruding portion and an outer edge of the second protruding portion is a first distance a; a protruding distance of the first protruding portion relative to the lower surface of the lower electrode layer is a second distance b; a protruding distance of the second protruding portion relative to the lower surface of the lower electrode layer is a third distance c; wherein b>c. According to the embodiments of the present disclosure, the upper surface of the lower electrode layer is a planarization surface; materials of the upper electrode layer and the lower electrode layer are combinations of one or more materials selected from molybdenum Mo, titanium Ti, tungsten W, gold Au, aluminum Al, and platinum Pt; and a material of the piezoelectric layer is aluminum nitride AlN, zinc oxide ZnO or lead zirconate titanate PZT. According to the embodiments of the present disclosure, the solidly mounted resonator includes: a substrate layer and a laminated structure. The substrate layer is disposed below the piezoelectric structure, and the laminated structure is disposed between the piezoelectric structure and the substrate layer, wherein the laminated structure sequentially comprises: a first low acoustic impedance layer, a first high acoustic impedance layer, a second low acoustic impedance layer, a second high acoustic impedance layer, and a third low acoustic impedance layer from bottom to top, wherein the third low acoustic impedance layer is disposed below the piezoelectric layer of the piezoelectric structure. According to the embodiments of the present disclosure, the third low acoustic impedance layer includes: a lower electrode slot recessed downward relative to an upper surface of the third low acoustic impedance layer, and the lower electrode slot includes: a first groove recessed downward corresponding to an edge of a bottom surface of the lower electrode slot; and a second groove recessed downward corresponding to a middle portion of the bottom surface of the lower electrode slot. According to the embodiments of the present disclosure, the first groove is a closed annular slot; a distance between an inner edge of the first groove and an outer edge of the second groove is a first distance a; a concave distance of the first groove relative to the bottom su