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US-12622184-B2 - Resistive switching device and fabrication method thereof

US12622184B2US 12622184 B2US12622184 B2US 12622184B2US-12622184-B2

Abstract

A resistive switching device includes a substrate; a first dielectric layer on the substrate; a conductive via in the first dielectric layer; a bottom electrode on the conductive via and the first dielectric layer, a resistive switching layer on the bottom electrode; and a cone-shaped top electrode on the resistive switching layer. The cone-shaped top electrode can produce increased and concentrated electric field during operation, which facilitates the filament forming process.

Inventors

  • Wen-Jen Wang
  • Yu-Huan Yeh
  • Chuan-Fu Wang

Assignees

  • UNITED MICROELECTRONICS CORP.

Dates

Publication Date
20260505
Application Date
20230710
Priority Date
20230605

Claims (20)

  1. 1 . A resistive switching device, comprising: a substrate; a first dielectric layer on the substrate; a conductive via in the first dielectric layer; a bottom electrode on the conductive via and the first dielectric layer; a resistive switching layer on the bottom electrode; and a cone-shaped top electrode on the resistive switching layer and comprising a tip, wherein a bottom width of the cone-shaped top electrode is wider than a width of the tip.
  2. 2 . The resistive switching device according to claim 1 , wherein the conductive via comprises tungsten.
  3. 3 . The resistive switching device according to claim 1 , further comprising a spacer layer covering the cone-shaped top electrode, wherein the pointed tip of the cone-shaped top electrode protrudes from an upper surface of the spacer layer.
  4. 4 . The resistive switching device according to claim 3 , wherein the spacer layer further covers a sidewall of the resistive switching layer and a top surface of the first dielectric layer.
  5. 5 . The resistive switching device according to claim 3 further comprising: a second dielectric layer on the spacer layer; and a contact penetrating through the second dielectric layer and the spacer layer and being electrically connected with the cone-shaped top electrode.
  6. 6 . The resistive switching device according to claim 1 , wherein the bottom electrode comprises TaN and the cone-shaped top electrode comprises TiN.
  7. 7 . The resistive switching device according to claim 1 , wherein the bottom electrode comprises a recessed sidewall.
  8. 8 . The resistive switching device according to claim 7 , wherein the spacer layer covering the recessed sidewall of the bottom electrode.
  9. 9 . The resistive switching device according to claim 1 , wherein a bottom width of the resistive switching layer connecting to the bottom electrode is greater than a bottom width of the bottom electrode away from the resistive switching layer.
  10. 10 . The resistive switching device according to claim 1 , wherein a width of the resistive switching layer is greater than a bottom width of the cone-shaped top electrode.
  11. 11 . A method for forming a resistive switching device, comprising: providing a substrate; forming a first dielectric layer on the substrate; forming a conductive via in the first dielectric layer; forming a bottom electrode on the conductive via and the first dielectric layer; forming a resistive switching layer on the bottom electrode; and forming a cone-shaped top electrode on the resistive switching layer, wherein the cone-shaped top electrode comprises a tip, and wherein a bottom width of the cone-shaped top electrode is wider than a width of the tip.
  12. 12 . The method according to claim 11 , wherein the conductive via comprises tungsten.
  13. 13 . The method according to claim 11 , further comprising a spacer layer covering the cone-shaped top electrode, wherein the pointed tip of the cone-shaped top electrode protrudes from an upper surface of the spacer layer.
  14. 14 . The method according to claim 13 , wherein the spacer layer further covers a sidewall of the resistive switching layer and a top surface of the first dielectric layer.
  15. 15 . The method according to claim 13 further comprising: forming a second dielectric layer on the spacer layer; and forming a contact penetrating through the second dielectric layer and the spacer layer and being electrically connected with the cone-shaped top electrode.
  16. 16 . The method according to claim 11 , wherein the bottom electrode comprises TaN and the cone-shaped top electrode comprises TiN.
  17. 17 . The method according to claim 11 , wherein the bottom electrode comprises a recessed sidewall.
  18. 18 . The method according to claim 17 , wherein the spacer layer covering the recessed sidewall of the bottom electrode.
  19. 19 . The method according to claim 11 , wherein a bottom width of the resistive switching layer connecting to the bottom electrode is greater than a bottom width of the bottom electrode away from the resistive switching layer.
  20. 20 . The method according to claim 11 , wherein a width of the resistive switching layer is greater than a bottom width of the cone-shaped top electrode.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to the field of semiconductor technology, in particular to a resistive switching device and a manufacturing method thereof. 2. Description of the Prior Art Resistive Random Access Memory (RRAM) is the general name for reprogrammable devices that can be set in a low-resistance or high-resistance state. RRAM typically consists of a dielectric layer disposed between two electrodes. Certain types of RRAM conduct by forming filaments in confined areas of the dielectric. Other types of RRAM can conduct by changing their properties across the dielectric region. RAM stores information by using the variable resistance properties of the dielectric layer between two electrodes. This dielectric layer, which acts as a resistive layer, is usually insulating, but can be made conductive by filaments or conductive paths formed (i.e., by a forming process) after application of a sufficiently high voltage. The formation of conductive paths may arise from different mechanisms, including defects, metal migration, etc. Once formed, filaments can still be reset (i.e. break, resulting in high resistance) or set (i.e. re-form, resulting in low resistance) by applying an appropriate voltage. The current RRAM structure is usually a vertical configuration with a single transistor and a single resistor. Due to the large current required, the size of the memory unit will be affected by the transistor. In addition, the filaments or conductive paths formed in the resistive switching layer of the RRAM structure are relatively fragile, and are easy to disappear in the harsher test environment in the subsequent baking process. SUMMARY OF THE INVENTION It is one object of the present invention to provide an improved resistive switching device and a manufacturing method thereof, in order to solve the deficiencies or shortcomings of the prior art. One aspect of the invention provides a resistive switching device including a substrate; a first dielectric layer on the substrate; a conductive via in the first dielectric layer; a bottom electrode on the conductive via and the first dielectric layer; a resistive switching layer on the bottom electrode; and a cone-shaped top electrode on the resistive switching layer. According to some embodiments, the conductive via comprises tungsten. According to some embodiments, the bottom electrode comprises TaN, TiN, Pt, Ir, Ru, or W. According to some embodiments, the cone-shaped top electrode comprises TiN, TaN, Pt, Ir, or W. According to some embodiments, the bottom electrode comprises TaN and the cone-shaped top electrode comprises TiN. According to some embodiments, the bottom electrode comprises a recessed sidewall. According to some embodiments, a width of the resistive switching layer is greater than a width of the bottom electrode. According to some embodiments, a width of the resistive switching layer is greater than a bottom width of the cone-shaped top electrode. According to some embodiments, the resistive switching device further includes a spacer layer covering the cone-shaped top electrode, a sidewall of the resistive switching layer, the recessed sidewall of the bottom electrode, and a top surface of the first dielectric layer; a second dielectric layer on the spacer layer; and a contact penetrating through the second dielectric layer and the spacer layer and being electrically connected with the cone-shaped top electrode. According to some embodiments, the resistive switching layer comprises a hafnium oxide layer and a titanium layer. Another aspect of the invention provides a method for forming a resistive switching device. A substrate is provided. A first dielectric layer is formed on the substrate. A conductive via is formed in the first dielectric layer. A bottom electrode is formed on the conductive via and the first dielectric layer. A resistive switching layer is formed on the bottom electrode. A cone-shaped top electrode is formed on the resistive switching layer. According to some embodiments, the conductive via comprises tungsten. According to some embodiments, the bottom electrode comprises TaN, TiN, Pt, Ir, Ru, or W. According to some embodiments, the cone-shaped top electrode comprises TIN, TaN, Pt, Ir. or W. According to some embodiments, the bottom electrode comprises TaN and the cone-shaped top electrode comprises TiN. According to some embodiments, the bottom electrode comprises a recessed sidewall. According to some embodiments, a width of the resistive switching layer is greater than a width of the bottom electrode. According to some embodiments, a width of the resistive switching layer is greater than a bottom width of the cone-shaped top electrode. According to some embodiments, the method further include the steps of forming a spacer layer covering the cone-shaped top electrode, a sidewall of the resistive switching layer, the recessed sidewall of the bottom electrode, and a top surface of the fi