Semiconductor memory having both volatile and non-volatile functionality and method of operating

• US 8,570,803 B2
• Filed: 02/04/2013
• Issued: 10/29/2013
• Est. Priority Date: 11/29/2006
• Status: Active Grant

• Current Assignee: Zeno Semiconductor, Inc.
• Original Assignee: Zeno Semiconductor, Inc.
• Inventors: Widjaja, Yuniarto
• Primary Examiner(s): Nguyen, Tuan T.
• Application Number:
  US13/758,646
• Publication Number:
  US 20130148422A1
• Time in Patent Office: 267 Days
• Field of Search: 365/185.08, 365/228
• US Class Current: 365/185.08
• CPC Class Codes: G11C 11/40 using transistors
• CPC Class Codes: G11C 11/404 with one charge-transfer gate, e.g. MOS transistor, per cell
• CPC Class Codes: G11C 14/0018 whereby the nonvolatile element is an EEPROM element, e.g. a floating gate or metal-nitride-oxide-silicon [MNOS] transistor
• CPC Class Codes: G11C 16/0416 comprising cells containing a single floating gate transistor and no select transistor, e.g. UV EPROM
• CPC Class Codes: G11C 2211/4016 Memory devices with silicon-on-insulator cells
• CPC Class Codes: H01L 29/66825 with a floating gate H01L29/6684 takes precedence
• CPC Class Codes: H01L 29/66833 with a charge trapping gate insulator, e.g. MNOS transistors
• CPC Class Codes: H01L 29/78 with field effect produced by an insulated gate H01L29/7725, H01L29/775, H01L29/778 take precedence
• CPC Class Codes: H01L 29/7841 with floating body, e.g. programmable transistors
• CPC Class Codes: H01L 29/7881 Programmable transistors with only two possible levels of programmation H01L29/7888 takes precedence
• CPC Class Codes: H10B 12/20 DRAM devices comprising floating-body transistors, e.g. floating-body cells

Abstract

Semiconductor memory having both volatile and non-volatile modes and methods of operation. A semiconductor memory cell includes a substrate having a first conductivity type; a first region embedded in the substrate at a first location of the substrate and having a second conductivity type; a second region embedded in the substrate at a second location the substrate and have the second conductivity type, such that at least a portion of the substrate having the first conductivity type is located between the first and second locations and functions as a floating body to store data in volatile memory; a floating gate or trapping layer positioned in between the first and second locations and above a surface of the substrate and insulated from the surface by an insulating layer; the floating gate or trapping layer being configured to receive transfer of data stored by the volatile memory and store the data as nonvolatile memory in the floating gate or trapping layer upon interruption of power to the memory cell; and a control gate positioned above the floating gate or trapping layer and a second insulating layer between the floating gate or trapping layer and the control gate.

Claims

1. A semiconductor memory cell comprising:

a floating body region;

a floating gate or trapping layer positioned above and insulated from said floating body region;

wherein said floating body region is configured to be charged to a level indicative of a state of the memory cell based on charge stored in said floating gate or trapping layer, upon restoration of power to said memory cell.

2. The semiconductor memory cell of claim 1, wherein said memory cell functions as volatile memory upon said restoration of power to said memory cell.

3. The semiconductor memory cell of claim 1, wherein said floating body region is configured to a predetermined state prior to being charged based on charge stored in said floating body or trapping layer.

4. The semiconductor memory cell of claim 1, wherein said floating gate or trapping layer is configured to a predetermined state after said floating body region is charged to a level based on charge stored in said floating gate or trapping layer.

5. The semiconductor memory cell of claim 1, further comprising a control gate positioned above said floating gate or trapping layer.

6. The semiconductor memory cell of claim 1, further comprising a first region in electrical contact with said floating body region and a second region spaced apart from said first region an in electrical contact with said floating body region.

7. The semiconductor memory cell of claim 1, wherein the semiconductor memory cell functions as a binary cell.

8. The semiconductor memory cell of claim 1, wherein the semiconductor memory cell functions as a multi-level cell.

9. A semiconductor memory cell comprising:

a floating body region; and

a floating gate or trapping layer positioned above and insulated from said floating body region;

wherein charge flow into said floating body region upon restoration of power to said memory cell depends on charge stored in said floating gate or trapping layer.

10. The semiconductor memory cell of claim 9, wherein said memory cell functions as volatile memory upon said restoration of power to said memory cell.

11. The semiconductor memory cell of claim 9, wherein said floating body region is configured to a predetermined state prior to being charged based on charge stored in said floating body or trapping layer.

12. The semiconductor memory cell of claim 9, wherein said floating gate or trapping layer is configured to a predetermined state after said floating body region is charged to a level based on charge stored in said floating gate or trapping layer.

13. The semiconductor memory cell of claim 9, further comprising a control gate positioned above said floating gate or trapping layer.

14. The semiconductor memory cell of claim 9, further comprising a first region in electrical contact with said floating body region and a second region spaced apart from said first region and in electrical contact with said floating body region.

15. The semiconductor memory cell of claim 9, wherein the semiconductor memory cell functions as a binary cell.

16. The semiconductor memory cell of claim 9, wherein the semiconductor memory cell functions as a multi-level cell.

17. A method of operating a semiconductor memory cell, said method comprising:

providing the memory cell to have a floating body for storing data as volatile memory and a floating gate or trapping layer for storing data as non-volatile memory; and

transferring the data stored in the floating gate or trapping layer to the floating body when power is restored to the memory cell.

18. The method of claim 17, wherein said transferring the data stored in the floating gate or trapping layer to the floating body is a non-algorithmic operation.

19. The method of claim 17, wherein the floating body region is configured to a predetermined state prior to be charged based on charge stored in the floating body or trapping layer.

20. The method of claim 17, wherein the floating gate or trapping layer is configured to a predetermined state after the floating body region is charged to a level based on charge stored in the floating gate or trapping layer.