Controlling ReRam forming voltage with doping

• US 9,012,260 B2
• Filed: 10/29/2014
• Issued: 04/21/2015
• Est. Priority Date: 12/18/2012
• Status: Expired due to Fees

• Current Assignee: Intermolecular Incorporated
• Original Assignee: Intermolecular Incorporated
• Inventors: Barabash, Sergey, Chen, Charlene, Pramanik, Dipankar
• Primary Examiner(s): Valentine, Jami M
• Application Number:
  US14/527,276
• Publication Number:
  US 20150064873A1
• Time in Patent Office: 174 Days
• Field of Search: 257 1- 5, 257/E29.002, 438102-104
• US Class Current: 438/102
• CPC Class Codes: H10B 63/80 Arrangements comprising multiple bistable or multi-stable switching components of the same type on a plane parallel to the substrate, e.g. cross-point arrays
• CPC Class Codes: H10N 70/023 by chemical vapor deposition, e.g. MOCVD, ALD
• CPC Class Codes: H10N 70/041 Modification of the switching material, e.g. post-treatment, doping
• CPC Class Codes: H10N 70/20 Multistable switching devices, e.g. memristors
• CPC Class Codes: H10N 70/24 based on migration or redistribution of ionic species, e.g. anions, vacancies
• CPC Class Codes: H10N 70/826 adapted for essentially vertical current flow, e.g. sandwich or pillar type devices
• CPC Class Codes: H10N 70/841 Electrodes
• CPC Class Codes: H10N 70/8833 Binary metal oxides, e.g. TaOx

Abstract

An internal electrical field in a resistive memory element can be formed to reduce the forming voltage. The internal electric field can be formed by incorporating one or more charged layers within the switching dielectric layer of the resistive memory element. The charged layers can include adjacent charge layers to form dipole layers. The charged layers can be formed at or near the interface of the switching dielectric layer with an electrode layer. Further, the charged layer can be oriented with lower valence substitution side towards lower work function electrode, and higher valence substitution side towards higher work function electrode.

Claims

1. A method to form a resistive memory cell, the method comprising

forming a first electrode having a first work function;

forming a dielectric layer on the first electrode,

wherein the dielectric layer is operable as a switching layer;

forming at least one charged layer within the dielectric layer;

wherein the at least one charged layer is formed by substituting one or more

precursors of a deposition process used to form the dielectric layer; and

forming a second electrode on the dielectric layer,

wherein the second electrode has a second work function, and

wherein the first work function is different from the second work function.

2. The method as in claim 1, wherein a work function of the first electrode and a work function of the second electrode differ by at least 1 eV.

3. The method as in claim 1, wherein the at least one charged layer is formed by alloying a portion of the dielectric layer.

4. The method as in claim 1, wherein the at least one charged layer comprises two adjacent charged layers of opposite polarities forming a dipole layer.

5. The method as in claim 4, wherein the two adjacent charged layers directly interface each other.

6. The method as in claim 4, wherein the two adjacent charged layers are separated by between about 0.3 nm and 3 nm.

7. The method as in claim 1, wherein the at least one charged layer comprises an element having lower valence than that of a metal element of the dielectric layer.

8. The method as in claim 7, wherein the element having lower valence than that of the metal element of the dielectric layer comprises greater than 10 at % of substitution within the dielectric layer.

9. The method as in claim 1, wherein the at least one charged layer comprises an element having a lower valence than that of oxygen.

10. The method as in claim 9, wherein the element having lower valence than that of oxygen comprises greater than 30 at % of substitution within the dielectric layer.

11. The method as in claim 1, wherein the at least one charged layer comprises an element having a higher valence than that of oxygen.

12. The method as in claim 11, wherein the element having higher valence than that of oxygen comprises greater than 30 at % of substitution within the dielectric layer.

13. The method as in claim 1, wherein the at least one charged layer comprises a charged layer located at a distance of less than 3 nm from an interface of the dielectric layer and the first electrode or an interface of the dielectric layer and the second electrode.

14. The method as in claim 1, wherein the at least one charged layer can be between 5% and 50% of a total thickness of the dielectric layer.

15. The method as in claim 1, wherein the dielectric layer is formed by an atomic layer deposition process utilizing one or more precursors.

16. The method as in claim 1, further comprising treating the dielectric layer using one of a rapid thermal oxidation at 300 C. in oxygen ambient or a plasma anneal in an oxygen ambient.

17. The method as in claim 1, wherein the second electrode comprises one MoO₂ or MoSi_xO_y.

18. The method as in claim 1, wherein the dielectric layer comprises one of ZrO₂, HfO₂, Al₂O₃, TiO₂, or ZnO.

19. The method as in claim 1, wherein a thickness of the dielectric layer can be between 1 nm and 10 nm.