RECESSED ACCESS DEVICES AND GATE ELECTRODES

• US 20140217498A1
• Filed: 04/08/2014
• Published: 08/07/2014
• Est. Priority Date: 05/11/2006
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Parekh, Kunal R., Smith, Casey, Gibbons, Jasper S., Young, Darren V.
• Granted Patent: US 9,502,516 B2
• Time in Patent Office: Days
• US Class Current: 257/331
• 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 first gate material in a trench in a semiconductor substrate, the first gate material having a first work function associated therewith; 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,

the first gate material electrically isolated from the second gate material.

2. The gate electrode of claim 1, further comprising a conductive strap in contact with the first gate material and the second gate material.

4. The gate electrode of claim 1, wherein each of the first gate material and the second gate material independently comprises a material selected from the group consisting of polysilicon, doped polysilicon, silicon, and doped silicon.

5. The gate electrode of claim 1, further comprising an insulator positioned between the first gate material and the second gate material, wherein the insulator provides electrical isolation between the first gate material and the second gate material.

6. The gate electrode of claim 5, wherein the insulator comprises a material selected from the group consisting of silicon nitride and silicon dioxide.

23. The gate electrode of claim 1, wherein the trench defines a middle portion and a bottom portion wider than the middle portion.

3. (canceled)

7. A recessed access device, comprising:

at least one trench in a semiconductor substrate;

an oxide material 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 the second gate material.

8. The recessed access device of claim 7, wherein the first gate material and the second gate material each contact the oxide layer.

9. The recessed access device of claim 7, wherein at least one of the first gate material and the second gate material comprises a material selected from the group consisting of polysilicon, doped polysilicon, and metal.

11. The recessed access device of claim 7, wherein:

the first gate material comprises a doped polysilicon material;

the second gate material comprises a doped polysilicon material; and

the first gate material and the second gate material are doped with different dopants.

12. The recessed access device of claim 7, wherein the second gate material comprises a material having a higher work function than a material of the first gate material.

10. (canceled)

13. A recessed access device, comprising:

at least one trench in a semiconductor substrate;

an oxide material 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 material;

an insulator overlying the first gate material;

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

an insulator cap overlying the second gate material.

14. The recessed access device of claim 13, 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.

15. The recessed access device of claim 13, wherein the first voltage supply and the second voltage supply originate from an access device driver.

16. A recessed access device, comprising:

at least one trench in a 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.

17. The recessed access device of claim 16, wherein at least one of the anode gate material and the cathode gate material comprises a material selected from the group consisting of polysilicon, doped polysilicon, metal, ruthenium-tantalum, and tantalum nitride.

19. The recessed access device of claim 16, wherein the cathode gate material comprises an n-type cathode material.

20. The recessed access device of claim 16, wherein the anode gate material comprises a p-type anode material.

21. The recessed access device of claim 16, wherein the diode comprises a Schottky-Barrier diode.

22. The recessed access device of claim 16, wherein the anode gate material and the cathode gate material are in direct contact with one another.

18. (canceled)