Memory cell comprising dynamic random access memory (DRAM) nanoparticles and nonvolatile memory (NVM) nanoparticle

• US 7,759,715 B2
• Filed: 10/15/2007
• Issued: 07/20/2010
• Est. Priority Date: 10/15/2007
• Status: Expired due to Fees

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Bhattacharyya, Arup
• Primary Examiner(s): Nguyen; Kimberly D
• Assistant Examiner(s): Karimy; Mohammad T
• Application Number:
  US11/872,130
• Publication Number:
  US 20090302365A1
• Time in Patent Office: 1,009 Days
• Field of Search: 257/296, 257/297, 257/298, 257/E27.084, 257/E21.679, 257/E21.662, 257/E21.209
• US Class Current: 257/296
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: H01L 29/40114 the electrodes comprising a conductor-insulator-conductor-insulator-semiconductor structure
• CPC Class Codes: H01L 29/40117 the electrodes comprising a charge-trapping insulator
• CPC Class Codes: H01L 29/42332 with the floating gate formed by two or more non connected parts, e.g. multi-particles flating gate
• CPC Class Codes: H01L 29/42348 with trapping site formed by at least two separated sites, e.g. multi-particles trapping site
• CPC Class Codes: H01L 29/513 the variation being perpendicular to the channel plane
• CPC Class Codes: H01L 29/7881 Programmable transistors with only two possible levels of programmation H01L29/7888 takes precedence
• CPC Class Codes: H01L 29/792 with charge trapping gate insulator, e.g. MNOS-memory transistors
• CPC Class Codes: H10B 12/05 Making the transistor
• CPC Class Codes: Y10S 977/777 Metallic powder or flake
• CPC Class Codes: Y10S 977/943 Information storage or retrieval using nanostructure

Abstract

Some embodiments include memory cells that contain a dynamic random access memory (DRAM) element and a nonvolatile memory (NVM) element. The DRAM element contains two types of DRAM nanoparticles that differ in work function. The NVM contains two types of NVM nanoparticles that differ in trapping depth. The NVM nanoparticles may be in vertically displaced charge-trapping planes. The memory cell contains a tunnel dielectric, and one of the charge-trapping planes of the NVM may be further from the tunnel dielectric than the other. The NVM charge-trapping plane that is further from the tunnel dielectric may contain larger NVM nanoparticles than the other NVM charge-trapping plane. The DRAM element may contain a single charge-trapping plane that has both types of DRAM nanoparticles therein. The memory cells may be incorporated into electronic systems.

Claims

1. A memory cell comprising:

a dynamic random access memory (DRAM) element that comprises two types of DRAM nanoparticles, the two types of DRAM nanoparticles being of different work function relative to one another;

a nonvolatile memory (NVM) element that comprises two types of NVM nanoparticles, the two types of NVM nanoparticles having different trapping depths relative to one another;

a tunnel dielectric;

wherein the two types of DRAM nanoparticles are within a common plane at a first distance from the tunnel dielectric; and

wherein;

one of the two types of NVM nanoparticles is within a plane at a second distance from the tunnel dielectric that is greater than the first distance; and

the other of the two types of NVM nanoparticles is within a plane at a third distance from the tunnel dielectric that is greater than the second distance.

2. The memory cell of claim 1 wherein one of the types of NVM nanoparticles forms a first population, wherein the other of the types of NVM nanoparticles forms a second population, and wherein the second population has an average cross-sectional dimension that is at least 10% different than an average cross-sectional dimension of the first population.

3. The memory cell of claim 1 wherein one of the DRAM nanoparticle types comprises tungsten and the other comprises platinum.

4. The memory cell of claim 1 wherein one of the DRAM nanoparticle types consists of tungsten and the other consists of platinum.

5. The memory cell of claim 1 wherein the NVM nanoparticle types differ in composition from one another, and comprise materials selected from the group consisting of Au, Ag, Co, conductively-doped Ge, Ir, Ni, Pd, Pt, Re, Ru, conductively-doped Si, Si—

Ge, Ta, Te, Ti, W and mixtures thereof.

6. The memory cell of claim 1 wherein one of the NVM nanoparticle types consists of tungsten and the other consists of platinum.

7. The memory cell of claim 1 wherein the NVM particles at the second distance have a shallower trapping depth than the type NVM particles at the third distance.

8. The memory cell of claim 1 wherein:

the NVM nanoparticles at the second distance from the tunnel dielectric form a first population,

the NVM nanoparticles at the third distance from the tunnel dielectric form a second population, and

the second population has an average cross-sectional dimension that is at least 10% larger than the average cross-sectional dimension of the first population.

9. A memory cell comprising:

a tunnel dielectric;

a first charge-trapping plane over the tunnel dielectric, the first charge-trapping plane comprising two different types of nanoparticles that differ in work function relative to one another, the two types of nanoparticles of the first charge-trapping plane being about the same in average maximum cross-sectional dimension as one another and being a first type of nanoparticles and a second type of nanoparticles;

a first dielectric over and between the nanoparticles of the first charge-trapping plane, the first dielectric layer having a first equivalent oxide thickness over the first charge-trapping plane;

a second charge-trapping plane over the first dielectric, the second charge-trapping plane comprising a third type of nanoparticles that have a third average maximum cross-sectional dimension;

a second dielectric over and between the third type of nanoparticles, the second dielectric having a second equivalent oxide thickness over the second charge-trapping plane;

the second equivalent oxide thickness being at least about 10% greater than the first equivalent oxide thickness;

a third charge-trapping plane over the second dielectric, the third charge-trapping plane comprising a fourth type of nanoparticles that have a fourth average maximum cross-sectional dimension, the fourth average maximum cross-sectional dimension being at least about 10% greater than the third average maximum cross-sectional dimension;

a third dielectric over and between the fourth type of nanoparticles; and

a control gate over the third dielectric.

10. The memory cell of claim 9 wherein one of the first and second types of nanoparticles comprises tungsten and the other comprises platinum.

11. The memory cell of claim 9 wherein the third and fourth types of nanoparticles comprise the same composition as one another.

12. The memory cell of claim 9 wherein the third and fourth types of nanoparticles comprise different compositions from one another.

13. The memory cell of claim 12 wherein one of the third and fourth types of nanoparticles comprises tungsten and the other comprises platinum.

14. The memory cell of claim 12 wherein the third type of nanoparticles comprises tungsten and the fourth type of nanoparticles comprises platinum.

15. The memory cell of claim 9 wherein:

the tunnel dielectric comprises one or both hafnium oxide or zirconium oxide;

the first dielectric comprises silicon dioxide;

the second dielectric comprises one or both of hafnium silicon oxynitride and zirconium silicon oxynitride; and

the third dielectric comprises one or both of hafnium silicon oxynitride and zirconium silicon oxynitride.

16. The memory cell of claim 15 wherein the control gate comprises conductively-doped silicon.

17. An electronic system, comprising:

a processor; and

memory in data communication with the processor, at least some of the memory comprising individual memory cells that include;

a tunnel dielectric;

a dynamic random access memory (DRAM) element over the tunnel dielectric and comprising a charge-trapping plane that contains two types of DRAM nanoparticles that are of different work function relative to one another; and

a nonvolatile memory (NVM) element over the DRAM element;

the NVM element comprising a first NVM charge-trapping plane containing a first population of NVM nanoparticles having a first average maximum cross-sectional dimension, the NVM element also comprising a second NVM charge-trapping plane over the first charge-trapping plane, the second NVM charge-trapping plane containing a second population of NVM nanoparticles having a second average maximum cross-sectional dimension that is at least 10% greater than the first average maximum cross-sectional dimension.

18. The electronic system of claim 17 wherein one of the two types of DRAM nanoparticles consists of platinum and the other consists of tungsten.

19. The electronic system of claim 17 wherein the nanoparticles of the first population consist of tungsten, and the nanoparticles of the second population consist of platinum.

20. The electronic system of claim 17 wherein the first NVM charge-trapping plane is spaced from the DRAM charge-trapping plane by a dielectric consisting of silicon dioxide.

21. The electronic system of claim 17 wherein the second NVM charge-trapping plane is spaced from the first NVM charge-trapping plane by a dielectric consisting of one or both of hafnium silicon oxynitride and zirconium silicon oxynitride.

22. The electronic system of claim 17 wherein the processor and memory are on the same integrated circuit chip as one another.

23. The electronic system of claim 17 wherein the memory is on one integrated circuit chip and the processor is on another integrated circuit chip.

24. The electronic system of claim 17 being a car, telephone, computer, camera, video recorder, television or airplane.