RECESSED MEMORY CELL ACCESS DEVICES AND GATE ELECTRODES

• US 20120061751A1
• Filed: 10/18/2011
• Published: 03/15/2012
• Est. Priority Date: 05/11/2006
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Gibbons, Jasper S., Parekh, Kunal R., Young, Darren V., Smith, Casey
• Granted Patent: US 8,692,320 B2
• Time in Patent Office: Days
• US Class Current: 257/330
• CPC Class Codes: H01L 21/823425 manufacturing common source or drain regions between a plurality of conductor-insulator-semiconductor structures
• CPC Class Codes: H01L 21/82345 gate conductors with different gate conductor materials or different gate conductor implants, e.g. dual gate structures
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/4236 within a trench, e.g. trench gate electrode, groove gate electrode
• CPC Class Codes: H01L 29/66621 using etching to form a recess at the gate location etching of semiconductor bodies H01L21/302
• CPC Class Codes: H01L 29/7831 with multiple gate structure FinFETs or MuGFETs H01L29/7855, thin film transistors H01L29/78645

Abstract

Recessed access transistor devices used with semiconductor devices may include gate electrodes having materials with multiple work functions, materials that are electrically isolated from each other and supplied with two or more voltage supplies, or materials that create a diode junction within the gate electrode.

Claims

1. A gate electrode, comprising:

a trench in a semiconductor substrate;

a first gate material in the trench, the first gate material having a first work function; and

a second gate material at least partially within the trench, the second gate material having a second work function different from the first work function.

3. The gate electrode of claim 1, further comprising a separator between the first gate material and the second gate material.

4. The gate electrode of claim 3, wherein the separator comprises a material selected from the group consisting of a nitride, an oxide, a silicide, a conductive metal, and a metallic alloy.

5. The gate electrode of claim 3, further comprising a conductive strap in contact with the first gate material and the second gate material.

7. The gate electrode of claim 1, further comprising a conductive material separating the first gate material and the second gate material.

8. The gate electrode of claim 7, wherein the conductive material comprises a material selected from the group consisting of metals, doped silicon, doped polysilicon, and conductive silicon materials.

9. The gate electrode of claim 1, wherein the first gate material is electrically isolated from the second gate material.

11. The gate electrode of claim 9, further comprising at least one additional gate material, wherein the at least one additional gate material is electrically isolated from the first gate material and the second gate material.

12. The gate electrode of claim 9, wherein the first gate material and the second gate material each comprise a material selected from the group consisting of polysilicon, doped polysilicon, silicon, and doped silicon.

13. The gate electrode of claim 9, wherein the first gate material is electrically isolated from the second gate material in the trench.

40. The recessed access device of claim 1, further comprising:

a first contact between the first gate material and a first voltage supply; and

a second contact between the second gate material and a second voltage supply.

41. The recessed access device of claim 40, wherein the first voltage supply and the second voltage supply originate from an access device driver.

42. The recessed access device of claim 40, wherein the first voltage supply and the second voltage supply are configured to provide the same or different voltages to the first contact and the second contact.

2. (canceled)

6. (canceled)

10. (canceled)

14-18. -18. (canceled)

19. A recessed access device, comprising:

a semiconductor substrate;

at least one trench in the semiconductor substrate;

an oxide layer positioned over sidewalls of the at least one trench;

a first gate material in a bottom portion of the at least one trench and overlying at least a portion of the oxide layer;

a second gate material in the at least one trench and overlying the first gate material; and

an insulator cap overlying the second gate material.

21. The recessed access device of claim 19, wherein the first gate material and the second gate material each contact the oxide layer.

24. The recessed access device of claim 19, wherein the first gate material comprises a doped polysilicon material and the second gate material comprises a doped polysilicon material, wherein the first gate material and the second gate material are doped with different dopants.

54. The recessed access device of claim 19, further comprising an electrical connection between the first gate material and the second gate material.

55. The recessed access device of claim 54, wherein the electrical connection comprises a barrier layer in contact with the first gate material and the second gate material.

56. The recessed access device of claim 55, wherein the barrier layer comprises a material selected from the group consisting of metal, doped polysilicon, doped silicon, and an insulator material.

57. The recessed access device of claim 19, further comprising an insulator overlying the first gate material, and the second gate material overlying the first gate material and the insulator.

20. (canceled)

22-23. -23. (canceled)

25-27. -27. (canceled)

28. A recessed access device, comprising:

a semiconductor substrate;

at least one trench in the semiconductor substrate;

an oxide layer positioned over sidewalls of the at least one trench;

a first gate material positioned over at least a portion of the sidewalls of the at least one trench;

a second gate material in the at least one trench and at least partially surrounded by the first gate material; and

an insulator cap overlying the first gate material and second gate material.

33. The recessed access device of claim 28, wherein the second gate material comprises a material having a higher work function than the first gate material.

29-32. -32. (canceled)

34-39. -39. (canceled)

43. A recessed access device, comprising:

a semiconductor substrate;

at least one trench in the semiconductor substrate;

an oxide layer positioned over sidewalls of the at least one trench;

an anode gate material in a bottom portion of the at least one trench and overlying at least a portion of the oxide layer;

a cathode gate material in the at least one trench and overlying the anode gate material, wherein the anode gate material and the cathode gate material form a diode; and

an insulator cap overlying the cathode gate material.

46. The recessed access device of claim 43, wherein the cathode gate material comprises a material selected from the group consisting of polysilicon, doped polysilicon, metal, ruthenium-tantalum, and tantalum nitride.

47. The recessed access device of claim 43, wherein the anode gate material comprises a doped polysilicon material and the cathode gate material comprises a doped polysilicon material, wherein the anode gate material and the cathode gate material are doped with different dopants.

53. The recessed access device of claim 43, wherein the diode comprises a Schottky-Barrier diode.

44-45. -45. (canceled)

48-52. -52. (canceled)