US-12620970-B2 - Integrated devices with multiple acoustic resonator chiplets

Abstract

A device includes a resonator stack. The resonator stack includes a first chiplet including a first acoustic resonator having a first resonant frequency and a second chiplet including a second acoustic resonator having a second resonant frequency that is different from the first resonant frequency. The device also includes a substrate coupled to the resonator stack, and electrical interconnections between the first chiplet and the second chiplet to provide a conductive path between the first acoustic resonator and the second acoustic resonator.

Inventors

• Jonghae Kim
• Je-Hsiung Lan
• Ranadeep Dutta

Assignees

• QUALCOMM INCORPORATED

Dates

Publication Date

20260505

Application Date

20240125

Claims (20)

1. 1 . A device comprising: a resonator stack comprising: a first chiplet including a first acoustic resonator having a first resonant frequency; and a second chiplet including a second acoustic resonator having a second resonant frequency that is different from the first resonant frequency; one or more additional chiplets that include one or more additional acoustic resonators having resonant frequencies different from the first resonant frequency and the second resonant frequency; wherein the first chiplet and the second chiplet are included in a filter circuit of the resonator stack; a substrate coupled to the resonator stack; and electrical interconnections between the first chiplet and the second chiplet to provide a conductive path between the first acoustic resonator and the second acoustic resonator.
2. 2 . The device of claim 1 , wherein the first acoustic resonator includes a first acoustic layer that has a first thickness, and wherein the second acoustic resonator includes a second acoustic layer that has a second thickness that is different from the first thickness.
3. 3 . The device of claim 2 , wherein the second thickness differs from the first thickness by at least a factor of two.
4. 4 . The device of claim 1 , wherein the first chiplet and the second chiplet are formed from different wafers.
5. 5 . The device of claim 1 , wherein the first chiplet and the second chiplet are included in a single stack layer of the resonator stack.
6. 6 . The device of claim 1 , wherein the first chiplet in included in a first stack layer of the resonator stack, and wherein the second chiplet is included in a second stack layer of the resonator stack that is on the first stack layer.
7. 7 . The device of claim 1 , wherein the filter circuit includes a ladder-type bandpass filter.
8. 8 . The device of claim 1 , wherein the filter circuit further includes the one or more additional acoustic resonators and is configured to operate as a broadband filter.
9. 9 . The device of claim 1 , wherein the resonator stack further includes: a first redistribution layer coupled to first components in a first stack layer; a second redistribution layer coupled to second components in a second stack layer; and a first set of through-mold vias electrically connecting the first redistribution layer to the second redistribution layer, and wherein the electrical interconnections are included in at least one of the first redistribution layer, the second redistribution layer, or the one or more through-mold vias.
10. 10 . The device of claim 1 , wherein the resonator stack further includes an inductor chiplet that includes multiple inductors.
11. 11 . The device of claim 1 , wherein the resonator stack further includes a capacitor chiplet that includes multiple capacitors.
12. 12 . A method of fabrication comprising: placing a first chiplet with a first acoustic resonator having a first resonant frequency on a substrate; placing a second chiplet with a second acoustic resonator having a second resonant frequency on the substrate, wherein the second resonant frequency is different from the first resonant frequency; placing one or more additional chiplets that include one or more additional acoustic resonators having resonant frequencies different from the first resonant frequency and the second resonant frequency; and electrically connecting the first chiplet and the second chiplet to provide a conductive path between the first acoustic resonator and the second acoustic resonator; wherein the first chiplet and the second chiplet are included in a filter circuit of the resonator stack.
13. 13 . The method of claim 12 , wherein the first chiplet is formed from a first wafer, and wherein the second chiplet is formed from a second wafer that is different from the first wafer.
14. 14 . The method of claim 13 , further comprising: disposing a mold compound that at least partially encapsulates the first chiplet and the second chiplet in a first stack layer of a resonator stack; and forming a second stack layer of the resonator stack on the first stack layer, the second stack layer including a third acoustic resonator having a third resonant frequency and a fourth acoustic resonator having a fourth resonant frequency.
15. 15 . A device comprising: a resonator stack comprising: a first stack layer including: a first chiplet including a first acoustic resonator having a first resonant frequency; and a second chiplet including a second acoustic resonator having a second resonant frequency that is different from the first resonant frequency; a second stack layer including: a third chiplet including a third acoustic resonator having a third resonant frequency; and a fourth chiplet including a fourth acoustic resonator having a fourth resonant frequency that is different from the third resonant frequency; and mold compound at least partially encapsulating the first chiplet, the second chiplet, the third chiplet, the fourth chiplet, and a set of through-mold conductors; first electrical interconnections between the first chiplet and the second chiplet to provide a first conductive path between the first acoustic resonator and the second acoustic resonator; second electrical interconnections between the third chiplet and the fourth chiplet to provide a second conductive path between the third acoustic resonator and the fourth acoustic resonator; wherein the first chiplet, the second chiplet, the third chiplet, and the fourth chiplet are included in a filter circuit of the resonator stack, the filter circuit is included in a duplexer.
16. 16 . The device of claim 15 , wherein the first acoustic resonator includes a first acoustic layer that has a first thickness, and wherein the second acoustic resonator includes a second acoustic layer that has a second thickness that is different from first thickness.
17. 17 . The device of claim 16 , wherein the second thickness differs from the first thickness by at least a factor of two.
18. 18 . The device of claim 15 , wherein the first chiplet is formed from a first wafer and the second chiplet is formed from a second wafer different than the first wafer.
19. 19 . The device of claim 15 , wherein the resonator stack further includes: a first redistribution layer coupled to first components in the first stack layer, the first redistribution layer including the first electrical interconnections; and a second redistribution layer coupled to second components in the second stack layer, the second redistribution layer including the second electrical interconnections, and wherein the set of through-mold conductors electrically connect the first redistribution layer to the second redistribution layer.
20. 20 . The device of claim 15 , wherein the resonator stack further includes an inductor chiplet that includes multiple inductors.

Description

FIELD Various features relate to acoustic resonators in integrated devices. BACKGROUND Cell phones and other radio frequency (RF) devices often utilize acoustic resonators, such as a bulk acoustic wave resonator (BAR), for filtering RF signals. A conventional acoustic resonator includes a thin film of a piezoelectric material, such as aluminum nitride (AlN), in an acoustic layer that is sandwiched between metal electrodes, and the acoustic resonator may be isolated from a substrate via an air gap. An applied RF signal drives the electrodes and generates resonant excitation in the piezoelectric layer at a resonant frequency for the acoustic resonator. The resonant frequency depends upon the thickness of the acoustic layer. Because the resonant frequency depends upon the thickness of the acoustic layer, designing an RF filter to operate across a wide range of frequencies requires multiple acoustic resonators having different thickness to provide the desired resonant frequencies. However, wafer process constraints limit an amount of variation of the thickness of the acoustic layer, in addition to preventing the integration of multiple different types of acoustic resonators on a wafer. The acoustic resonators on the wafer are therefore constrained to a narrow range of resonant frequencies and, as a result, RF filtering using the acoustic resonators is constrained to a relatively narrow range of frequencies. SUMMARY Various features relate to acoustic resonators in integrated devices. One example provides a device that includes a resonator stack. The resonator stack includes a first chiplet including a first acoustic resonator having a first resonant frequency and a second chiplet including a second acoustic resonator having a second resonant frequency that is different from the first resonant frequency. The device includes a substrate coupled to the resonator stack. The device also includes electrical interconnections between the first chiplet and the second chiplet to provide a conductive path between the first acoustic resonator and the second acoustic resonator. Another example provides a device that includes a resonator stack. The resonator stack includes a first stack layer and a second stack layer. The first stack layer includes a first chiplet including a first acoustic resonator having a first resonant frequency, and a second chiplet including a second acoustic resonator having a second resonant frequency that is different from the first resonant frequency. The second stack layer includes a third chiplet including a third acoustic resonator having a third resonant frequency, and a fourth chiplet including a fourth acoustic resonator having a fourth resonant frequency that is different from the third resonant frequency. The resonator stack also includes mold compound at least partially encapsulating the first chiplet, the second chiplet, the third chiplet, the fourth chiplet, and a set of through-mold conductors. The device also includes first electrical interconnections between the first chiplet and the second chiplet to provide a first conductive path between the first acoustic resonator and the second acoustic resonator. The device further includes second electrical interconnections between the third chiplet and the fourth chiplet to provide a second conductive path between the third acoustic resonator and the fourth acoustic resonator. Another example provides a method for fabricating an integrated device. The method includes placing a first chiplet with a first acoustic resonator having a first resonant frequency on a substrate, and placing a second chiplet with a second acoustic resonator having a second resonant frequency on the substrate. The method also includes electrically connecting the first chiplet and the second chiplet to provide a conductive path between the first acoustic resonator and the second acoustic resonator. BRIEF DESCRIPTION OF THE DRAWINGS Various features, nature and advantages may become apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify correspondingly throughout. FIG. 1 illustrates a schematic cross-sectional view of an example of an exemplary integrated device having multiple acoustic resonator chiplets. FIG. 2 illustrates a schematic cross-sectional view of another example of the exemplary integrated device of FIG. 1. FIG. 3 illustrates a schematic cross-sectional view of another example of the exemplary integrated device of FIG. 1. FIG. 4 illustrates a schematic cross-sectional view of another example of the exemplary integrated device of FIG. 1. FIG. 5 illustrates schematic views and circuit characteristics associated with exemplary acoustic resonators that may be included in the exemplary integrated device of FIG. 1. FIG. 6 illustrates an exemplary sequence for fabricating the exemplary integrated device of FIG. 1. FIGS. 7A, 7B and 7C together illustrate another exemplary seque