Resistive random access memory having charge trapping layer, manufacturing method thereof, and operation thereof

1. A resistive random access memory, comprising:

a first electrode;

a second electrode, located on the first electrode;

a charge trapping layer, located between the first electrode and the second electrode, wherein the charge trapping layer comprises:

a first region, having a first dopant and being close to the first electrode; and

a second region, having a second dopant and being close to the second electrode, wherein the first region and the second region have a same insulating material, and the first dopant and the second dopant are respectively formed in an insulating material of the first region and the second region.

2. The resistive random access memory as claimed in claim 1 , wherein the insulating material with an energy gap smaller than 5 eV comprises at least one insulating material selected from a group consisting of TiO 2 , NiO, HfO, HfO 2 , ZrO, ZrO 2 , Ta 2 O 5 , ZnO, WO 3 , CoO and Nb 2 O 5 .

3. The resistive random access memory as claimed in claim 1 , wherein the first dopant comprises at least one element selected from a group consisting of Ti, Zr, Fe, Co, Al, S, N, Ca, Cu, Pb, Sr, Hf, B, C, Mo, Zn, Mg.

4. The resistive random access memory as claimed in claim 1 , wherein a concentration of the first dopant in the first region is between 1 at % and 50 at %.

5. The resistive random access memory as claimed in claim 1 , wherein the second dopant comprises at least one element selected from a group consisting of Ti, Zr, Fe, Co, Al, S, N, Ca, Cu, Pb, Sr, Hf, B, C, Mo, Zn, Mg.

6. The resistive random access memory as claimed in claim 1 , wherein a concentration of the second dopant in the second region is between 10 at % and 90 at %.

7. The resistive random access memory as claimed in claim 1 , wherein an energy gap of the second region is greater than an energy gap of the first region by at least 1 eV.

8. The resistive random access memory as claimed in claim 1 , wherein the first dopant is different to the second dopant.

9. The resistive random access memory as claimed in claim 1 , wherein the first dopant is the same to the second dopant, and a concentration of the first dopant in the first region and a concentration of the second dopant in the second region present a gradient distribution.

10. The resistive random access memory as claimed in claim 1 , wherein the first electrode extends along a first direction, the second electrode extends along a second direction, and the first direction is substantially perpendicular to the second direction.

11. The resistive random access memory as claimed in claim 10 , wherein the number of the first electrodes is plural, the first electrodes and a plurality of dielectric layers extend along the first direction, and are stacked with each other along a third direction, wherein the charge trapping layer at least covers sidewalls of the first electrodes.

12. The resistive random access memory as claimed in claim 11 , wherein the charge trapping layer conformally covers a surface of the first electrodes and the dielectric layers.

13. The resistive random access memory as claimed in claim 11 , wherein at least one memory cell is formed at an overlapped portion of each of the first electrodes and the corresponding second electrode.

14. A manufacturing method of a resistive random access memory, comprising:

providing a first electrode;

forming a charge trapping layer on the first electrode; and

forming a second electrode on the charge trapping layer, wherein the charge trapping layer comprises:

a first region, having a first dopant and being close to the first electrode; and

a second region, having a second dopant and being close to the second electrode, wherein the first region and the second region have a same insulating material, and the first dopant and the second dopant are respectively formed in an insulating material of the first region and the second region.

15. The manufacturing method of the resistive random access memory as claimed in claim 14 , wherein a method for forming the charge trapping layer comprises an atomic layer deposition process, and the atomic layer deposition process comprises:

performing a plurality of first deposition cycles to form a plurality of first material layers having the insulating material;

performing a plurality of second deposition cycles to form a plurality of second material layers having the first dopant, wherein the number of times of the first deposition cycles is greater than the number of times of the second deposition cycles; and

repeating the first deposition cycles and the second deposition cycles until the first region of the charge trapping layer is formed.

16. The manufacturing method of the resistive random access memory as claimed in claim 15 , wherein the atomic layer deposition process further comprises:

performing a plurality of third deposition cycles to form a third material layer having the insulating material;

performing a plurality of fourth deposition cycles to form a fourth material layer having the second dopant, wherein the number of times of the fourth deposition cycles is greater than the number of times of the third deposition cycles; and

repeating the third deposition cycles and the fourth deposition cycles until the second region of the charge trapping layer is formed.

17. An operation of a resistive random access memory, comprising:

providing the resistive random access memory as claimed in claim 1 ;

in a setting operation, applying a positive bias to the second electrode, such that a plurality of electrons is injected to the first region of the charge trapping layer from the first electrode, and is blocked by the second region of the charge trapping layer; and

in a resetting operation, applying a negative bias to the second electrode, such that the electrons are escaped to the first electrode from the first region of the charge trapping layer.

18. The operation of the resistive random access memory as claimed in claim 17 , further comprising:

in a read operation, applying a negative bias to the second electrode, such that Fowler-Nordheim (FN) electrons are injected to the first region from the second electrode, and a high resistance state or a low resistance state is determined according to a sum of the electrons in the first region.

19. The operation of the resistive random access memory as claimed in claim 17 , wherein before the setting or the resetting operation is performed, a forming operation is not performed.