# US 11,309,352 B2 · Integrated acoustic filter on complementary metal oxide semiconductor (CMOS) die

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- Number: US 11,309,352 B2
- Document ID: US11309352B2
- Status: Granted
- Kind: B2
- Application number: 16/116,744
- Filed: 2018-08-29
- Published: 2019-09-05
- Granted: 2022-04-19
- Earliest claimed: 2018-03-01
- Assignees: QUALCOMM Incorporated
- Applicants: QUALCOMM Incorporated
- Inventors: Sinan Goktepeli; Stephen Alan Fanelli; Yun Han Chu
- Web page: https://patentgrep.com/patent/US11309352B2

## CPC

- H10N 39/00: Integrated devices, or assemblies of multiple devices, comprising at least one piezoelectric, electrostrictive or magnetostrictive element covered by groups H10N30/00 – H10N35/00
- B81C 1/00246: {Monolithic integration, i.e. micromechanical structure and electronic processing unit are integrated on the same substrate}
- H03H 3/0073: {Integration with other electronic structures}
- H03H 3/02: for the manufacture of piezoelectric or electrostrictive resonators or networks (H03H3/08 takes precedence)
- H03H 3/08: for the manufacture of resonators or networks using surface acoustic waves
- H03H 9/0547: {consisting of a vertical arrangement (H03H9/0566 takes precedence)}
- H03H 9/0557: {the other elements being buried in the substrate}
- H03H 9/0561: {consisting of a multilayered structure}
- H03H 9/1014: {the enclosure being defined by a frame built on a substrate and a cap, the frame having no mechanical contact with the BAW device}
- H03H 9/1071: {the enclosure being defined by a frame built on a substrate and a cap, the frame having no mechanical contact with the SAW device}
- H03H 9/465: {in combination with other electronic elements}
- H03H 9/545: {including active elements}
- H03H 9/564: {implemented with thin-film techniques}
- H03H 9/64: using surface acoustic waves
- B81B 2201/0271: Resonators; ultrasonic resonators
- H03H 9/0571: {including bulk acoustic wave [BAW] devices}
- H03H 9/0576: {including surface acoustic wave [SAW] devices}
- H03H 2001/0064: {comprising semiconductor material}
- H03H 2003/021: {the resonators or networks being of the air-gap type}
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- B81C: PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS (making microcapsules or microballoons B01J13/02; processes or apparatus specially adapted for the manufacture or treatment of piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/01)
- H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P)
- B81B: MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES (piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/00, H10N35/00)

## Abstract

A radio frequency (RF) front-end (RFFE) device includes a die having a front-side dielectric layer on an active device. The active device is on a first substrate. The RFFE device also includes a microelectromechanical system (MEMS) device. The MEMS device is integrated on the die at a different layer than the active device. The MEMS device includes a cap layer composed of a cavity in the front-side dielectric layer of the die. The cavity in the front-side dielectric layer is between the first substrate and a second substrate. The cap is coupled to the front-side dielectric layer.

## Claims

### Claim 1

A radio frequency (RF) front-end (RFFE) device, comprising:
a die including a front-side dielectric layer on an active device, the active device on a first semiconductor substrate located at a back-side of the die, and a plurality of back-end-of-line layers between the active device and the front-side dielectric layer; and
a microelectromechanical system (MEMS) device integrated on the die at a different layer than the active device, the MEMS device having a cap layer comprised of a cavity in the front-side dielectric layer of the die, between the first semiconductor substrate and a second semiconductor substrate coupled to the front-side dielectric layer,
in which the MEMS device comprises an acoustic filter, comprising:
a second dielectric layer between the second semiconductor substrate and bonded to the front-side dielectric layer of the die and arranged opposite the cap layer; and
a piezoelectric layer between a first electrode and a second electrode, the first electrode coupled to the second dielectric layer and an inert layer of the acoustic filter, the first electrode coupled to the active device through a first back-end-of-line (BEOL) interconnect, and the second electrode coupled to the dielectric layer and the inert layer of the acoustic filter, the second electrode coupled to a second BEOL interconnect.

### Claim 2 (depends on 1)

The RFFE device of claim 1, in which the second semiconductor substrate comprises a semiconductor handle wafer, and in which the acoustic filter further comprises an inert gas between the semiconductor handle wafer and at least one of the first electrode and the second electrode.

### Claim 3 (depends on 1)

The RFFE device of claim 1 in which the acoustic filter comprises a bulk acoustic wave (BAW) filter.

### Claim 4 (depends on 1)

The RFFE device of claim 1, further comprising a bond layer between the second semiconductor substrate of the MEMS device and the front-side dielectric layer of the die.

### Claim 5 (depends on 1)

The RFFE device of claim 1, in which the die comprises a complementary metal oxide semiconductor (CMOS) die or a radio frequency (RF) die.

### Claim 6 (depends on 1)

The RFFE device of claim 1, in which the first semiconductor substrate comprises a semiconductor-on-insulator (SOI) wafer, and the second semiconductor substrate comprises a semiconductor handle wafer.

### Claim 7 (depends on 1)

The RFFE device of claim 1, integrated into at least one of a music player, a video player, an entertainment unit, a navigation device, a communications device, a personal digital assistant (PDA), a fixed location data unit, a mobile phone, and a portable computer.

### Claim 8

A radio frequency (RF) front-end (RFFE) device, comprising:
a die including a front-side dielectric layer on an active device, the active device on a first semiconductor substrate located at a back-side of the die, and a plurality of back-end-of-line layers between the active device and the front-side dielectric layer; and
a microelectromechanical system (MEMS) device integrated on the die at a different layer than the active device, the MEMS device having a cap layer comprised of a cavity in the front-side dielectric layer of the die, between the first semiconductor substrate and a second semiconductor substrate coupled to the front-side dielectric layer in which the MEMS device comprises an acoustic filter, comprising:
a piezoelectric layer on the second semiconductor substrate, the piezoelectric layer bonded to the front-side dielectric layer; and
a first electrode between the piezoelectric layer and the front-side dielectric layer and also between the piezoelectric layer and the cavity, the first electrode coupled to the active device through a first back-end-of-line (BEOL) interconnect.

### Claim 9 (depends on 8)

The RFFE device of claim 8, in which the acoustic filter comprises a surface acoustic wave (SAW) filter.

### Claim 10 (depends on 8)

The RFFE device of claim 8, further comprising a bond layer between the second semiconductor substrate of the MEMS device and the front-side dielectric layer of the die.

### Claim 11 (depends on 8)

The RFFE device of claim 8, in which the die comprises a complementary metal oxide semiconductor (CMOS) die or a radio frequency (RF) die.

### Claim 12 (depends on 8)

The RFFE device of claim 8, in which the first semiconductor substrate comprises a semiconductor-on-insulator (SOI) wafer, and the second semiconductor substrate comprises a semiconductor handle wafer.

### Claim 13

A radio frequency (RF) front-end (RFFE) device, comprising:
an RFFE die including a front-side dielectric layer on an active device, the active device on a first semiconductor substrate located at a back side of the RFFE die, and a plurality of back-end-of-line layers between the active device and the front-side dielectric layer; and an acoustic filter integrated on the die at a different layer than the active device, the acoustic filter having a cap layer comprised of a cavity in the front-side dielectric layer of the die, between the first semiconductor substrate and a second semiconductor substrate coupled to the front-side dielectric layer, the acoustic filter comprising a second dielectric layer between the second semiconductor substrate and bonded to the front-side dielectric layer of the die and arranged opposite the cap layer; and a piezoelectric layer between a first electrode and a second electrode, the first electrode coupled to the second dielectric layer and an inert layer of the acoustic filter, the first electrode coupled to the active device through a first back-end-of-line (BEOL) interconnect, and the second electrode coupled to the dielectric layer and the inert layer of the acoustic filter, the second electrode coupled to a second BEOL interconnect; and
an antenna coupled to an output of the acoustic filter.

### Claim 14 (depends on 13)

The RFFE device of claim 13, in which the acoustic filter
comprises a bulk acoustic wave (BAW) filter.

### Claim 15 (depends on 13)

The RFFE device of claim 13, incorporated into at least one of a music player, a video player, an entertainment unit, a navigation device, a communications device, a personal digital assistant (PDA), a fixed location data unit, a mobile phone, and a portable computer.

### Claim 16

A radio frequency (RF) front-end (RFFE) device, comprising:
an RFFE die including a front-side dielectric layer on an active device, the active device on a first semiconductor substrate located at a back side of the RFFE die, and a plurality of back-end-of-line layers between the active device and the front-side dielectric layer; and an acoustic filter integrated on the die at a different layer than the active device, the acoustic filter having a cap layer comprised of a cavity in the front-side dielectric layer of the die, between the first semiconductor substrate and a second semiconductor substrate coupled to the front-side dielectric layer, the acoustic filter comprising a filter layer on the second semiconductor substrate, the filter layer bonded to the front-side dielectric layer; and a first electrode between the filter layer and the front-side dielectric layer and also between the piezoelectric layer and the cavity, the first electrode coupled to the active device through a first back-end-of-line (BEOL) interconnect, in which the acoustic filter comprises a surface acoustic wave (SAW) filter; and
an antenna coupled to an output of the acoustic filter.