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EP-4032623-B1 - ELECTRONIC DEVICE AND METHOD FOR FABRICATING A TRANSDUCER IN THE ELECTRONIC DEVICE

EP4032623B1EP 4032623 B1EP4032623 B1EP 4032623B1EP-4032623-B1

Inventors

  • WAN, Wei-lin
  • LIU, YU-TSUNG
  • YANG, HUI-CHING
  • LEE, TE-YU

Dates

Publication Date
20260506
Application Date
20211222

Claims (13)

  1. An electronic device (10), comprising: a plurality of transducer pixels (12), each transducer pixel comprises: a sonic transducer (32); a first demultiplexer (34) electrically connected to the sonic transducer; the electronic device being characterized in that , the first demultiplexer comprises at least two transistors (36a, 36b) having gate electrodes (38a, 38b) ; and each transducer pixel further comprises: a driving line (14) electrically connected to the sonic transducer (32); a switching line (16) comprising two branch lines (16a, 16b) electrically connected to the gate electrodes (38a, 38b) of the at least two transistors (36a, 36b) of the first demultiplexer (34); and a reading line (18) electrically connected to the first demultiplexer (34), wherein the driving line (14) is configured to provide a driving signal to the sonic transducer (32) to emit sonic waves, and the switching line (16) is configured to turn on the first demultiplexer (34) to output a sensing signal received by the sonic transducer (32) to the reading line (18); and wherein the electronic device further comprises a driving circuit (26a) electrically connected to a second demultiplexer (24), wherein the second demultiplexer (24) comprises at least two transistors (40a, 40b) having source electrodes (42a, 42b) configured to receive a driving signal (28) and a reference signal (30) respectively.
  2. The electronic device as claimed in claim 1, wherein the sonic transducer (32) comprises a lower electrode (88), a piezoelectric layer (90) and an upper electrode (92), and the piezoelectric layer is between the upper electrode and the lower electrode.
  3. The electronic device as claimed in claim 2, further comprising a cavity (86) in an insulating layer (74) below the lower electrode (88).
  4. The electronic device as claimed in claim 1, wherein the sonic transducer (32) comprises a lower electrode (88), an insulating layer (68), a cavity (86) and an upper electrode (92), and the cavity is in the insulating layer between the lower electrode and the upper electrode.
  5. The electronic device as claimed in any of the preceding claims, wherein the sonic transducer (32) is a piezoelectric micromachined ultrasonic transducer (PMUT) or a capacitive micromachined ultrasonic transducer (CMUT).
  6. A method for fabricating an electronic device according to claims 1, 2 or 3, the steps of fabricating the sonic transducer, comprising: providing a substrate (50); forming a driving layer (51) on the substrate (50); forming a sacrificial layer (94) on the driving layer (51); forming a piezoelectric layer (90) on the driving layer (51); and etching the sacrificial layer (94) comprising: forming an insulating layer (80) on the sacrificial layer (94), forming a through hole (84) corresponding to the sacrificial layer (94) in the insulating layer (80), and providing an etching solution into the through hole (84) to etch the sacrificial layer (94) to form a cavity (86); wherein the step of etching the sacrificial layer (94) is before forming the piezoelectric layer (90), said method further comprising: forming an upper electrode (92) on the through hole (84), the piezoelectric layer (90) and the cavity (86).
  7. The method for fabricating the electronic device as claimed in claim 6, further comprising: forming a lower electrode (88); and wherein the piezoelectric layer (90) is between the upper electrode (92) and the lower electrode (88).
  8. A method for fabricating an electronic device according to claims 1 or 4, the steps of fabricating the sonic transducer, comprising: providing a substrate (50); forming a driving layer (51) on the substrate (50), wherein the driving layer comprises a lower electrode (88); forming a sacrificial layer (94) on the lower electrode (88); forming an upper electrode (92) on the sacrificial layer (94); and removing the sacrificial layer (94) to form a cavity (86), wherein the cavity is between the upper electrode (92) and the lower electrode (88).
  9. The method for fabricating the electronic device as claimed in claim 8, wherein the step of removing the sacrificial layer (94) comprises: forming an insulating layer (80) on the sacrificial layer (94); forming a through hole (84) corresponding to the sacrificial layer (94) in the insulating layer (80); and providing an etching gas into the through hole.
  10. The method for fabricating the electronic device as claimed in claim 8 or 9, wherein the step of removing the sacrificial layer (94) comprises: forming an eutectic reaction in the sacrificial layer (94).
  11. The method for fabricating the electronic device as claimed in claim 10, wherein the sacrificial layer (94) comprises a double-layer structure formed by stacking an amorphous silicon layer (96) and a nickel layer (98).
  12. The method for fabricating the electronic device as claimed in claim 10, wherein the eutectic reaction is formed by an annealing process.
  13. The method for fabricating the electronic device as claimed in any of claims 9 to 12, further comprising forming a silicide layer (100) on the lower electrode (88) after the eutectic reaction.

Description

BACKGROUND Technical Field The present disclosure relates to an electronic device, and in particular it relates to a sonic transducer and a method for fabricating the same. Description of the Related Art The core component of the sonic-wave sensing system is, for example, a micromachined ultrasonic transducer (MUT), which is currently one of the focuses of active development in the industry. So far, most MUTs are based on passive matrices and are fabricated on wafers. Three-dimensional array images cannot be realized. The MUT and external circuits need to be integrated by wafer bonding, which is costly and difficult to fabricate a large-area MUT. US 2018/080839 A1 discloses an electronic device according to the preamble of claim 1, embodied as a test probe for use in characterizing piezoelectric material. EP 3 362 943 A1 discloses a An ultrasonic sensor pixel includes a substrate, a piezoelectric micromechanical ultrasonic transducer (PMUT) and a sensor pixel circuit. US 10 478 858 82 discloses a piezoelectric micromechanical ultrasonic transducer (PMUT) including a multilayer stack disposed on a substrate and a method for manufacturing thereof, including the removal of a sacrificial layer by means of etching. EP 3 723 287 A1 discloses an ultrasound transducer driver circuit (UTDC) including a half-bridge output stage for driving an ultrasound transducer. US 2016/071463 A1 discloses a driver circuit for driving display devices. US 2018/107854 A1 discloses integrated piezoelectric MEMS transducers (PMUTs) on integrated circuit (IC) for fingerprint sensing. None of the afore-mentioned documents discloses a first demultiplexer comprising at least two transistors having gate electrodes, and the switching line comprises two branch lines electrically connected to the gate electrodes of the at least two transistors nor a driving circuit electrically connected to a second demultiplexer which comprises at least two transistors having source electrodes configured to receive a driving signal and a reference signal respectively. SUMMARY It is an object of the present invention to provide an electronic device comprising plurality of transducer pixels each comprising a sonic transducer enabling a further reduction in costs and/or a more efficient large-area production. It is a further objection of the present invention to provide a corresponding method for fabricating the sonic transducer unit of the electronic device. These problems are solved by an electronic device as claimed in claim 1, and by a method for fabricating a sonic transducer as claimed in claim 6 and 8, respectively. A detailed description is given in the following embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The disclosure may be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: FIG. 1 is a circuit diagram of an electronic device in accordance with one embodiment of the present disclosure;FIG. 2-1 is a circuit diagram in an electronic device in accordance with one embodiment of the present disclosure;FIG. 2-2 is a circuit diagram in an electronic device in accordance with one embodiment of the present disclosure;FIG. 3-1 shows a top view of a sonic transducer in accordance with one embodiment of the present disclosure;FIG. 3-2 shows a schematic cross-sectional view taken along the cross-sectional lines A-A' and B-B' of FIG. 3-1 in accordance with one embodiment of the present disclosure;FIG. 3-3 shows a schematic cross-sectional view of a method for fabricating a sonic transducer in accordance with one embodiment of the present disclosure;FIG. 4-1 shows a top view of a sonic transducer in accordance with one embodiment of the present disclosure;FIG. 4-2 shows a schematic cross-sectional view taken along the cross-sectional lines A-A' and B-B' of FIG. 4-1 in accordance with one embodiment of the present disclosure;FIG. 4-3 shows a schematic cross-sectional view of a method for fabricating a sonic transducer in accordance with one embodiment of the present disclosure; andFIG. 4-3-2 shows a schematic cross-sectional view of a method for fabricating a sonic transducer in accordance with one embodiment of the present disclosure. DETAILED DESCRIPTION Various embodiments or examples are provided in the following description to implement different features of the present disclosure. The elements and arrangement described in the following specific examples are merely provided for introducing the present disclosure and serve as examples without limiting the scope of the present disclosure. For example, when a first component is referred to as "on a second component", it may directly contact the second component, or there may be other components in between, and the first component and the second component do not come in direct contact with one another. In addition, when the terms "comprising", "including" and/or "having" are used