Semiconductor memory having both volatile and non-volatile functionality and method of operating
Semiconductor memory having both volatile and non-volatile modes and methods of operation. A semiconductor memory cell includes a fin structure extending from a substrate, the fin structure including a floating substrate region having a first conductivity type configured to store data as volatile memory; first and second regions interfacing with the floating substrate region, each of the first and second regions having a second conductivity type; first and second floating gates or trapping layers positioned adjacent opposite sides of the floating substrate region; a first insulating layer positioned between the floating substrate region and the floating gates or trapping layers, the floating gates or trapping layers being configured to receive transfer of data stored by the volatile memory and store the data as nonvolatile memory in the floating gates or trapping layers upon interruption of power to the memory cell; a control gate wrapped around the floating gates or trapping layers and the floating substrate region; and a second insulating layer positioned between the floating gates or trapping layers and the control gate; the substrate including an isolation layer that isolates the floating substrate region from a portion of the substrate below the isolation layer.
1. A method of operating a memory cell having a fin structure including a floating substrate region for storing, reading and writing data as volatile memory, and a floating gate or trapping layer for storing data as non-volatile memory, the method comprising:
reading and storing data to the floating substrate region of the fin structure while power is applied to the memory cell;
transferring the data stored in the floating substrate region to the floating gate or trapping layer when power to the cell is interrupted; and
storing the data in the floating gate or trapping layer as non-volatile memory.
2. The method of claim 1 , wherein the data stored in the floating substrate region is stored as volatile memory.
3. The method of claim 1 , further comprising:
transferring the data stored in the floating gate or trapping layer to the floating substrate region when power is restored to the cell;
and storing the data in the floating substrate region as volatile memory.
4. The method of claim 1 , wherein the data transferred is stored in the floating gate or trapping layer with a charge that is complementary to a charge of the floating substrate region when storing the data.
5. The method of claim 1 , wherein the transferring is a non-algorithmic process.
6. The method of claim 5 , wherein the transferring is a parallel, non-algorithmic process.
7. The method of claim 3 , wherein the transferring is a non-algorithmic process.
8. The method of claim 3 , further comprising restoring the floating gate or trapping layer to a predetermined charge state.
9. The method of claim 3 , further comprising writing a predetermined state to the floating substrate region prior to the transferring the data stored in the floating gate or trapping layer to the floating substrate region.
10. The method of claim 9 , wherein the predetermined state is state “0”.