Semiconductor memory having both volatile and non-volatile functionality including resistance change material and method of operating
Semiconductor memory is provided wherein a memory cell includes a capacitorless transistor having a floating body configured to store data as charge therein when power is applied to the cell. The cell further includes a nonvolatile memory comprising a resistance change element configured to store data stored in the floating body under any one of a plurality of predetermined conditions. A method of operating semiconductor memory to function as volatile memory, while having the ability to retain stored data when power is discontinued to the semiconductor memory is described.
1. A semiconductor memory cell comprising:
a capacitorless transistor having a floating body configured to store data as charge therein when power is applied to said cell, said floating body having a first conductivity type selected from n-type conductivity type and p-type conductivity type; first and second regions at first and second locations of said cell, said first and second regions each having a second conductivity type selected from said n-type conductivity type and said p-type conductivity type and being different from said first conductivity type; said first and second regions being located such that at least a portion of the floating body is located between said first and second locations; and
a nonvolatile memory comprising a resistance change element electrically connected to one of said first and second regions and configured to store data stored in said floating body under any one of a plurality of predetermined conditions on said capacitorless transistor.
2. The semiconductor memory cell of claim 1 , wherein said resistance change element comprises a phase change material.
3. The semiconductor memory cell of claim 1 , wherein said resistance change element comprises a metal-oxide-metal system.
4. The semiconductor memory cell of claim 1 wherein one of said conditions comprises an instruction to back up said data stored in said floating body.
5. The semiconductor memory cell of claim 1 , wherein one of said predetermined conditions comprises loss of power to said cell, wherein said cell is configured to perform a shadowing process wherein said data in said floating body is loaded into and stored in said nonvolatile memory.
6. The semiconductor memory cell of claim 5 , wherein said loss of power to said cell is one of unintentional power loss or intentional power loss, wherein intentional power loss is predetermined to conserve power.
7. The semiconductor memory cell of claim 5 , wherein, upon restoration of power to said cell, said data in said nonvolatile memory is loaded into said floating body and stored therein.
8. The semiconductor memory cell of claim 7 , wherein said cell is configured to reset said nonvolatile memory to an initial state after loading said data into said floating body upon said restoration of power.
9. The semiconductor memory cell of claim 8 , wherein said resistance change element is configured to be set to a high resistance state in a first state and is configured to be set to a low resistance state as a second state, and wherein said reset to said initial state comprises resetting said resistance change element to said high resistance state.
10. The semiconductor memory cell of claim 8 , wherein said resistance change element is configured to be set to a high resistance state in a first state and is configured to be set to a low resistance state as a second state, and wherein said reset to said initial state comprises resetting said resistance change element to said low resistance state.
11. A semiconductor memory array, including:
a plurality of semiconductor memory cells as recited in claim 1 arranged in a matrix of rows and columns.
12. A semiconductor memory cell comprising:
a capacitorless transistor having a floating body configured to store data as charge therein when power is applied to said cell; and
a nonvolatile memory comprising a resistance change element configured to store data stored in said floating body under any one of a plurality of predetermined conditions;
wherein one of said predetermined conditions comprises loss of power to said cell, wherein said cell is configured to perform a shadowing process wherein said data in said floating body is loaded into and stored in said nonvolatile memory;
wherein, upon restoration of power to said cell, said data in said nonvolatile memory is loaded into said floating body and stored therein; and
wherein said cell is configured to reset said nonvolatile memory to an initial state after loading said data into said floating body upon said restoration of power.
13. The semiconductor memory cell of claim 12 , wherein said resistance change element is configured to be set to a high resistance state in a first state and is configured to be set to a low resistance state as a second state, and wherein said reset to said initial state comprises resetting said resistance change element to said high resistance state.
14. The semiconductor memory cell of claim 12 , wherein said resistance change element is configured to be set to a high resistance state in a first state and is configured to be set to a low resistance state as a second state, and wherein said reset to said initial state comprises resetting said resistance change element to said low resistance state.