# US 2014/0191825 A1 · Radio frequency filter and manufacturing method thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0191825 A1 - Document ID: US20140191825A1 - Status: Published application - Kind: A1 - Application number: 14/077,777 - Filed: 2013-11-12 - Published: 2014-07-10 - Earliest claimed: 2013-01-09 - Assignees: Samsung Electronics Co., Ltd. - Applicants: Samsung Electronics Co., Ltd. - Inventors: Sang Uk SON; Ho Soo PARK; Jea Shik SHIN; Duck Hwan KIM; Chul Soo KIM; In Sang SONG; Moon Chul LEE - Web page: https://patentgrep.com/patent/US20140191825A1 ## CPC - H03H 9/02102: {of temperature influence (cutting angles H03H9/02015)} - H03H 3/04: for obtaining desired frequency or temperature coefficient - H03H 9/173: {Air-gaps} - H03H 9/568: {consisting of a ladder configuration} - H03H 9/588: {Membranes} - H03H 9/605: {consisting of a ladder configuration} - H03H 2003/0407: {Temperature coefficient} - Y10T 29/42: Piezoelectric device making - H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A radio frequency filter and a manufacturing method thereof are provided. A radio frequency filter includes bulk acoustic wave resonators (BAWRs), the BAWRs including first BAWRs connected in series, second BAWRs connected in parallel, or a combination thereof. ## Claims ### Claim 1 A radio frequency filter comprising bulk acoustic wave resonators (BAWRs), the BAWRs comprising first BAWRs connected in series, second BAWRs connected in parallel, or a combination thereof. ### Claim 2 (depends on 1) The radio frequency filter of claim 1, wherein at least one of the BAWRs comprises: a membrane, a first electrode, a piezoelectric layer, and a second electrode, disposed in that order above a first substrate, at least a portion of the membrane being spaced apart from the first substrate as to form an air cavity therebetween. ### Claim 3 (depends on 2) The radio frequency filter of claim 2, wherein the at least one of the BAWRs further comprises a temperature coefficient of frequency (TCF) compensation layer configured to compensate for a TCF of the first electrode, the piezoelectric layer, or the second electrode. ### Claim 4 (depends on 2) The radio frequency filter of claim 2, wherein the at least one of the BAWRs further comprises a protection layer disposed on the second electrode. ### Claim 5 (depends on 3) The radio frequency filter of claim 3, wherein the TCF compensation layer is disposed between the piezoelectric layer and the second electrode, and a width of the TCF compensation layer is less than or equal to a width of the piezoelectric layer or a width of the second electrode. ### Claim 6 (depends on 3) The radio frequency filter of claim 3, wherein the TCF compensation layer is disposed between the piezoelectric layer and the first electrode, and a width of the TCF compensation layer is less than or equal to a width of the piezoelectric layer or a width of the first electrode. ### Claim 7 (depends on 3) The radio frequency filter of claim 3, wherein the TCF compensation layer is disposed between the first electrode and the membrane, and a width of the TCF compensation layer is less than or equal to a width of the first electrode or a width of the membrane. ### Claim 8 (depends on 3) The radio frequency filter of claim 3, wherein the TCF compensation layer is disposed between the second electrode and a protection layer, and a width of the TCF compensation layer is less than or equal to a width of the piezoelectric layer or a width of the protection layer. ### Claim 9 (depends on 1) The radio frequency filter of claim 1, wherein at least one of the first BAWRs comprises a TCF compensation layer. ### Claim 10 (depends on 1) The radio frequency filter of claim 1, wherein at least one of the second BAWRs comprises a TCF compensation layer. ### Claim 11 (depends on 2) The radio frequency filter of claim 2, further comprising: a second substrate bonded to the first substrate as to form a second air cavity between the first substrate and a lower surface of the second substrate. ### Claim 12 (depends on 1) The radio frequency filter of claim 1, wherein at least one of the first BAWRs comprises a TCF compensation layer configured to compensate for a change due to a temperature change of a high frequency band in a bandwidth of a radio frequency filter, and at least one of the second BAWRs comprises a TCF compensation layer configured to compensate for a change due to a temperature change of a low frequency band in a bandwidth of the radio frequency filter. ### Claim 13 (depends on 3) The radio frequency filter of claim 3, wherein the TCF compensation layer comprises at least one selected from the group consisting of a silicon oxide type, a silicon nitride type, a polymer, a carbon material, a metal, and a metal oxide material. ### Claim 14 (depends on 2) The radio frequency filter of claim 2, wherein the BAWRs each comprise a first electrode, a piezoelectric layer, and a second electrode; and a plurality of the second electrodes of the first BAWRs is connected to a plurality of second electrodes of the second BAWRs. ### Claim 15 (depends on 2) The radio frequency filter of claim 2, wherein the BAWRs each comprise a first electrode, a piezoelectric layer, and a second electrode; and a plurality of second electrodes of the first BAWRs is connected to a plurality of first electrodes of the second BAWRs. ### Claim 16 A method for manufacturing a radio frequency filter, the method comprising: forming a silicon oxide film, a silicon nitride film, and a sacrificial layer above a substrate in that order; patterning the sacrificial layer according to a shape of an air cavity; forming a silicon oxide film, a silicon nitride film, a first conductive layer above the patterned sacrificial layer in that order; forming a first electrode from the first conductive layer; forming a piezoelectric layer and a second conductive layer above the first electrode; forming a second electrode from the second conductive layer, based on at least one of a serial connection, a parallel connection, or a combination thereof of bulk acoustic wave resonators (BAWRs); forming a protection layer on the second electrode; generating the air cavity by removing the sacrificial layer; and generating a via hole by etching the substrate. ### Claim 17 (depends on 16) The method of claim 16, further comprising: depositing a temperature coefficient of frequency (TCF) compensation material on the piezoelectric layer, subsequent to the forming of the piezoelectric layer; and forming a TCF compensation layer having a width less than or equal to a width of the piezoelectric layer or a width of the second electrode by patterning the TCF compensation material. ### Claim 18 (depends on 16) The method of claim 16, further comprising: depositing a TCF compensation material on the first electrode, subsequent to the forming of the first electrode; and forming a TCF compensation layer having a width less than or equal to a width of the first electrode or a width of the piezoelectric layer by patterning the TCF compensation material. ### Claim 19 A method for manufacturing a radio frequency filter, the method comprising: forming a sacrificial layer on a first substrate; forming a first electrode, a piezoelectric layer, a temperature coefficient of frequency (TCF) compensation layer, and a second electrode above the sacrificial layer; removing the sacrificial layer to generate an air cavity, wherein the TCF compensation layer is formed either between the first electrode and the piezoelectric layer or between the piezoelectric layer and the second electrode. ### Claim 20 (depends on 19) The method of claim 19, wherein the second electrode is formed as to connect a plurality of bulk acoustic wave resonators (BAWRs) in a serial connection or a parallel connection.