Phase change material radio-frequency switch for low power consumption and methods for forming the same

1 . A device structure comprising:

a heater line located over a substrate;

an aluminum nitride layer having an inhomogeneous material composition, wherein a top surface portion of the aluminum nitride layer has a higher atomic concentration of nitrogen than a bottom surface portion of the aluminum nitride layer contacting a top surface of the heater line, wherein a vertical profile of an atomic concentration of nitrogen within the aluminum nitride layer has multiple local peaks between a bottom surface of the aluminum nitride layer and a top surface of the aluminum nitride layer, and each of the multiple local peaks has a respective magnitude that increases with a vertical distance from the bottom surface of the aluminum nitride layer; and

a phase change material (PCM) line comprising a middle portion that overlies the heater line, a first end portion adjoined to a first side of the middle portion, and a second end portion adjoined to a second side of the middle portion.

2 . The device structure of claim 1 , further comprising:

a first electrode connected to the first end portion of the PCM line; and

a second electrode connected to the second end portion of the PCM line.

3 . The device structure of claim 2 , further comprising:

a first electrode contact via structure connected to the first electrode;

a second electrode contact via structure connected to the second electrode;

a first heater contact via structure connected to a first end portion of the heater line; and

a second heater contact via structure connected to a second end portion of the heater line.

4 . The device structure of claim 2 , further comprising:

a first conductive barrier plate located between the first end portion of the PCM line and the first electrode; and

a second conductive barrier plate located between the second end portion of the PCM line and the second electrode.

5 . The device structure of claim 4 , wherein each of the first conductive barrier plate and the second conductive barrier plate comprises a material selected from titanium nitride, tantalum nitride, and tungsten nitride.

6 . The device structure of claim 2 , further comprising:

a first electrode-capping dielectric plate located on a top surface of the first electrode; and

a second electrode-capping dielectric plate located on a top surface of the second electrode.

7 . The device structure of claim 1 , further comprising a dielectric isolation layer located over the substrate and contacting a bottom surface of the heater line.

8 . The device structure of claim 7 , further comprising a dielectric matrix layer laterally surrounding the heater line and the aluminum nitride layer and having a top surface located within a horizontal plane including a top surface of the aluminum nitride layer.

9 . The device structure of claim 1 , wherein an atomic percentage of nitrogen atoms in the aluminum nitride layer increases continuously from an interface with the heater line to an interface with the PCM line.

10 . The device structure of claim 1 , further comprising:

semiconductor devices located on the substrate;

dielectric material layers overlying the semiconductor devices and underlying the heater line; and

metal interconnect structures located within the dielectric material layers and electrically connected to a respective one of the semiconductor devices, wherein the heater line is electrically connected to a respective one of the metal interconnect structures.

11 . The device structure of claim 1 , wherein the PCM line comprises a chalcogenide phase change material selected from GeSbTe, GeTe, InSe, SbTe, GaSb, InSb, AsTe, or AlTe.

12 . The device structure of claim 1 , wherein the heater line comprises a refractory metal nitride selected from titanium nitride, tantalum nitride, or tungsten nitride.

13 . The device structure of claim 1 , wherein:

the PCM line laterally extends along a first horizontal direction;

the heater line and the aluminum nitride layer laterally extend along a second horizontal direction that is perpendicular to the first horizontal direction; and

sidewalls of the heater line are vertically coincident with sidewalls of the aluminum nitride layer.

14 . A device structure comprising:

a heater line located over a substrate;

an inhomogeneous aluminum nitride layer comprising a vertical stack of component aluminum nitride liners, wherein a vertical profile of an atomic concentration of nitrogen within the inhomogeneous aluminum nitride layer has multiple local peaks between a bottom surface of the inhomogeneous aluminum nitride layer and a top surface of the inhomogeneous aluminum nitride layer; and

a phase change material (PCM) line comprising a middle portion that overlies the heater line, a first end portion adjoined to a first side of the middle portion, and a second end portion adjoined to a second side of the middle portion, wherein the multiple local peaks comprise at least three local peaks, and a peak-to-peak distance between neighboring pairs of peaks in the inhomogeneous aluminum nitride layer in the vertical profile decreases with a vertical distance from a top surface of the heater line toward the PCM line.

15 . The device structure of claim 14 , wherein each of the multiple local peaks has a respective magnitude that increases with a vertical distance from the bottom surface of the inhomogeneous aluminum nitride layer.

16 . The device structure of claim 14 , wherein the multiple local peaks have a same magnitude.

17 . The device structure of claim 14 , wherein:

the PCM line laterally extends along a first horizontal direction;

the heater line and the inhomogeneous aluminum nitride layer laterally extend along a second horizontal direction that is substantially perpendicular to the first horizontal direction; and

sidewalls of the heater line are vertically coincident with sidewalls of the inhomogeneous aluminum nitride layer.

18 . The device structure of claim 14 , wherein a bottom surface portion of the inhomogeneous aluminum nitride layer has a metallic property including a higher thermal conductivity and a higher electrical conductivity than a top surface portion of the inhomogeneous aluminum nitride layer.

19 . A device structure comprising:

a heater line located over a substrate;

an aluminum nitride layer having an inhomogeneous material composition, wherein a vertical profile of an atomic concentration of nitrogen within the aluminum nitride layer has multiple local peaks between a bottom surface of the aluminum nitride layer and a top surface of the aluminum nitride layer, and each of the multiple local peaks has a respective magnitude that increase with a vertical distance from the bottom surface of the inhomogeneous aluminum nitride layer;

a phase change material (PCM) line comprising a middle portion that overlies the heater line, a first end portion adjoined to a first side of the middle portion, and a second end portion adjoined to a second side of the middle portion; and

a dielectric matrix layer laterally surrounding the heater line and the aluminum nitride layer and having a top surface located within a horizontal plane including a top surface of the aluminum nitride layer.

20 . The device structure of claim 19 , wherein a top surface portion of the aluminum nitride layer has a higher atomic concentration of nitrogen than a bottom surface portion of the aluminum nitride layer.