Heating element designs for phase-change material (PCM) radio frequency (RF) switches

• US 10,566,528 B1
• Filed: 12/14/2018
• Issued: 02/18/2020
• Est. Priority Date: 08/14/2018
• Status: Active Grant

• Current Assignee: Newport Fab, LLC (Tower Semiconductor Limited)
• Original Assignee: Newport Fab, LLC (Tower Semiconductor Limited)
• Inventors: El-Hinnawy, Nabil, Slovin, Gregory P., DeBar, Michael J., Rose, Jefferson E., Howard, David J.
• Primary Examiner(s): Kebede, Brook
• Application Number:
  US16/221,252
• Publication Number:
  US 20200058863A1
• Time in Patent Office: 431 Days
• Field of Search: 438 48, 257 2, 365153
• CPC Class Codes: H10N 70/231 based on solid-state phase change, e.g. between amorphous and crystalline phases, Ovshinsky effect
• CPC Class Codes: H10N 70/823 adapted for essentially horizontal current flow, e.g. bridge type devices
• CPC Class Codes: H10N 70/841 Electrodes
• CPC Class Codes: H10N 70/8613 Heating or cooling means other than resistive heating electrodes, e.g. heater in parallel
• CPC Class Codes: H10N 70/8825 Selenides, e.g. GeSe
• CPC Class Codes: H10N 70/8828 Tellurides, e.g. GeSbTe

Abstract

A radio frequency (RF) switch includes a heating element, a phase-change material (PCM) situated over the heating element, and PCM contacts situated over passive segments of the PCM. The heating element extends transverse to the PCM. The heating element can have a heater line underlying an active segment of the PCM. Alternatively, the heating element can have a split heater lines underlying an active segment of the PCM. The split heater lines increase an area of the active segment of the PCM and reduce a heater-to-PCM parasitic capacitance. A fan-out structure having fan-out metal can connect the heater line to a heater contact. The fan-out structure reduces heat generation outside the active segment of the PCM and reduces a heater contact-to-PCM parasitic capacitance. The fan-out structure can have dielectric segments interspersed between the fan-out metal to reduce dishing.

Claims

1. A radio frequency (RF) switch comprising:

a heating element;

a phase-change material (PCM) situated over said heating element;

PCM contacts situated over passive segments of said PCM;

said heating element extending transverse to said PCM, a heater line of said heating element underlying an active segment of said PCM;

a fan-out structure comprising fan-out metal for connecting said heater line of said heating element to a heater contact;

said fan-out structure reducing heat generation outside said active segment of said PCM and reducing a heater contact-to-PCM parasitic capacitance.

2. The RF switch of claim 1, wherein said fan-out structure comprises dielectric segments interspersed between said fan-out metal to reduce dishing in said fan-out structure.

3. The RF switch of claim 1, wherein said fan-out structure is wider near said heater contact and narrower near said heater line.

4. The RF switch of claim 3, wherein said fan-out structure is laid out as a straight line trapezoid.

5. The RF switch of claim 3, wherein said fan-out structure is laid out as a stepped trapezoid.

6. The RF switch of claim 1, wherein said fan-out structure is separated from said PCM by a standoff region.

7. A radio frequency (RF) switch comprising:

a heating element;

a phase-change material (PCM) situated over said heating element;

PCM contacts situated over passive segments of said PCM;

said heating element extending transverse to said PCM, said heating element comprising split heater lines underlying an active segment of said PCM;

said split heater lines of said heating element resulting in an increase in an area of said active segment and reducing a heater-to-PCM parasitic capacitance.

8. The RF switch of claim 7, wherein said split heater lines consist of two heater lines.

9. The RF switch of claim 7, wherein said split heater lines consist of more than two heater lines.

10. The RF switch of claim 7, wherein said active segment of said PCM overlies a region between said split heater lines.

11. The RF switch of claim 7, wherein said split heater lines of said heating element increase a breakdown voltage of said RF switch.

12. A radio frequency (RF) switch comprising:

a heating element;

a phase-change material (PCM) situated over said heating element;

PCM contacts situated over passive segments of said PCM;

said heating element extending transverse to said PCM, said heating element comprising split heater lines underlying an active segment of said PCM;

a fan-out structure comprising fan-out metal for connecting said split heater lines of said heating element to a heater contact;

said split heater lines of said heating element resulting in an increase in an area of said active segment and reducing a heater-to-PCM parasitic capacitance.

13. The RF switch of claim 12, wherein said fan-out structure reduces heat generation outside said active segment of said PCM and reduces a heater contact-to-PCM parasitic capacitance.

14. The RF switch of claim 12, wherein said fan-out structure comprises dielectric segments interspersed between said fan-out metal to reduce dishing in said fan-out structure.

15. The RF switch of claim 12, wherein said active segment of said PCM overlies a region between said split heater lines.

16. The RF switch of claim 12, wherein said split heater lines of said heating element increase a breakdown voltage of said RF switch.

17. The RF switch of claim 12, wherein said fan-out structure is wider near said heater contact and narrower near said heater line.

18. The RF switch of claim 17, wherein said fan-out structure is laid out as a straight line trapezoid.

19. The RF switch of claim 17, wherein said fan-out structure is laid out as a stepped trapezoid.

20. The RF switch of claim 12, wherein said fan-out structure is separated from said PCM by a standoff region.