Method of operating semiconductor memory device with floating body transistor using silicon controlled rectifier principle

• US 8,559,257 B2
• Filed: 09/26/2011
• Issued: 10/15/2013
• Est. Priority Date: 08/05/2008
• Status: Active Grant

• Current Assignee: Zeno Semiconductor, Inc.
• Original Assignee: Zeno Semiconductor, Inc.
• Inventors: Widjaja, Yuniarto
• Primary Examiner(s): LE, TOAN K
• Application Number:
  US13/244,916
• Publication Number:
  US 20120113712A1
• Time in Patent Office: 750 Days
• Field of Search: 365/222, 365/189.01, 365/174, 365/189.03, 257/402, 257/E29.255
• US Class Current: 365/222
• CPC Class Codes: G11C 11/404 with one charge-transfer gate, e.g. MOS transistor, per cell
• CPC Class Codes: G11C 11/406 Management or control of the refreshing or charge-regeneration cycles
• CPC Class Codes: G11C 11/4076 Timing circuits for regeneration management G11C11/406
• CPC Class Codes: G11C 11/4096 Input/output [I/O] data management or control circuits, e.g. reading or writing circuits, I/O drivers or bit-line switches
• CPC Class Codes: G11C 2211/4016 Memory devices with silicon-on-insulator cells
• CPC Class Codes: H01L 29/7841 with floating body, e.g. programmable transistors
• CPC Class Codes: H10B 12/20 DRAM devices comprising floating-body transistors, e.g. floating-body cells

Abstract

A method of maintaining the data state of a semiconductor dynamic random access memory cell is provided, wherein the memory cell comprises a substrate being made of a material having a first conductivity type selected from p-type conductivity type and n-type conductivity type; a first region having a second conductivity type selected from the p-type and n-type conductivity types, the second conductivity type being different from the first conductivity type; a second region having the second conductivity type, the second region being spaced apart from the first region; a buried layer in the substrate below the first and second regions, spaced apart from the first and second regions and having the second conductivity type; a body region having the first conductivity type; and a gate positioned between the first and second regions and adjacent the body region.

Claims

1. A semiconductor memory cell comprising:

a floating body region configured to be charged to a level indicative of a state of the memory cell;

a first region in electrical contact with said floating body region;

a second region in electrical contact with said floating body region and spaced apart from said first region;

a gate positioned between said first and second regions;

a buried layer region in electrical contact with said floating body region, below said first and second regions, spaced apart from said first and second regions; and

a substrate region configured to inject charge into said floating body region to hold the state of said memory cell.

2. The cell of claim 1, wherein said first region has a first conductivity type selected from a p-type conductivity type and an n-type conductivity type;

said floating body region has a second conductivity type selected from said p-type and n-type conductivity types, said second conductivity type being different from said first conductivity type;

said second region has said first conductivity type;

said buried layer region has said first conductivity type; and

said substrate has said second conductivity type.

3. The cell of claim 1, further comprising insulating layers bounding the side surfaces of said floating body region.

4. The cell of claim 1, further comprising:

a source line terminal electrically connected to one of said first and second regions;

a bit line terminal electrically connected to the other of said first and second regions;

a word line terminal connected to said gate;

a buried well terminal connected to said buried layer; and

a substrate terminal connected to said substrate.

5. The cell of claim 1, wherein said holding the state of said memory cell is a non-algorithmic process.

6. The cell of claim 1, wherein said floating body region and first and second regions are formed in a fin that extends above said buried layer, said gate is provided on opposite sides of said fin, between said first and second regions, and said floating body region is between said first and second regions.

7. The cell of claim 1, wherein said floating body region and said first and second regions are formed in a fin that extends above said buried layer, said gate is provided on opposite sides and adjacent to a top surface of said fin, between said first and second regions, and said floating body region is between said first and second regions.

8. A semiconductor memory cell comprising:

a floating body region configured to be charged to a level indicative of a state of the memory cell;

a first region in electrical contact with said floating body region;

a second region in electrical contact with said floating body region and spaced apart from said first region;

a gate positioned between said first and second regions;

a buried layer region in electrical contact with said floating body region, below said first and second regions, spaced apart from said first and second regions; and

a substrate region configured to inject charge into said floating body region, wherein;

said substrate region, said buried layer region, said floating body region, and either of said first or second regions form a silicon controlled rectifier device.

9. The cell of claim 8, wherein said first region has a first conductivity type selected from a p-type conductivity type and an n-type conductivity type;

said floating body region has a second conductivity type selected from said p-type and n-type conductivity types, said second conductivity type being different from said first conductivity type;

said second region has said first conductivity type;

said buried layer region has said first conductivity type; and

said substrate has said second conductivity type.

10. The cell of claim 8, further comprising insulating layers bounding the surfaces of said floating body region.

11. The cell of claim 8, further comprising:

a source line terminal electrically connected to one of said first and second regions;

a bit line terminal electrically connected to the other of said first and second regions;

a word line terminal connected to said gate;

a buried well terminal connected to said buried layer; and

a substrate terminal connected to said substrate.

12. The semiconductor memory cell of claim 8, wherein said substrate region is configured to inject charge into said floating body region to hold the state of said memory cell.

13. The semiconductor memory cell of claim 8, wherein said silicon controlled rectifier device is configured to store the state of said memory cell.

14. The semiconductor memory cell of claim 8, wherein said silicon controlled rectifier device is configured to read the state of said memory cell.

15. The cell of claim 8, wherein said floating body region and first and second regions are formed in a fin that extends above said buried layer, said gate is provided on opposite sides of said fin, between said first and second regions, and said floating body region is between said first and second regions.

16. The cell of claim 8, wherein said floating body region and said first and second regions are formed in a fin that extends above said buried layer, said gate is provided on opposite sides and adjacent to a top surface of said fin, between said first and second regions, and said floating body region is between said first and second regions.

17. A semiconductor memory array comprising:

a plurality of semiconductor memory cells arranged in a matrix of rows and columns, wherein each said semiconductor memory cell includes;

a floating body region configured to be charged to a level indicative of a state of the memory cell;

a first region in electrical contact with said floating body region;

a second region in electrical contact with said floating body region and spaced apart from said first region;

a gate positioned between said first and second regions;

a buried layer region in electrical contact with said floating body region, below said first and second regions, spaced apart from said first and second regions; and

a substrate region configured to inject charge into or extract charge out of said floating body region to hold said state of the memory cell.

18. The semiconductor memory array of claim 17, wherein said substrate region of at least one said memory cells are connected to a substrate terminal.

19. The semiconductor memory array of claim 18, wherein said holding the state of said memory cell is a parallel, non-algorithmic process.

20. The semiconductor memory array of claim 18, wherein said holding the state of said memory cell is a parallel, non-algorithmic process to a plurality of said memory cells connected to said substrate terminal.

21. The semiconductor memory array of claim 18, wherein said substrate terminal is commonly connected to all of said cells in said array.

22. The semiconductor memory array of claim 18, wherein said substrate terminal is segmented to allow independent control of bias applied on a selected portion of said memory array.

23. The semiconductor memory array of claim 18, wherein said holding operation is performed by applying periodic pulses to said substrate terminal.

24. The semiconductor memory array of claim 18, wherein said holding operation is performed by applying constant voltage bias to said substrate terminal.

25. The semiconductor memory array of claim 17, wherein:

said floating body has a first conductivity type selected from a p-type conductivity type and an n-type conductivity type;

said first region has a second conductivity type selected from said p-type and n-type conductivity types, said second conductivity type being different from said first conductivity type;

said second region has said second conductivity type;

said buried layer region has said second conductivity type; and

said substrate region has said first conductivity type.

26. The array of claim 17, wherein said floating body region and first and second regions are formed in a fin that extends above said buried layer, said gate is provided on opposite sides of said fin, between said first and second regions, and said floating body region is between said first and second regions.

27. The cell of claim 17, wherein said floating body region and said first and second regions are formed in a fin that extends above said buried layer, said gate is provided on opposite sides and adjacent to a top surface of said fin, between said first and second regions, and said floating body region is between said first and second regions.