Semiconductor memory having electrically floating body transistor
Methods of maintaining a state of a memory cell without interrupting access to the memory cell are provided, including applying a back bias to the cell to offset charge leakage out of a floating body of the cell, wherein a charge level of the floating body indicates a state of the memory cell; and accessing the cell.
1. A semiconductor memory cell comprising:
a transistor comprising a source region, a floating body region, a drain region, and a gate;
a first bipolar device having a first floating base region, a first emitter, and a first collector; and
a second bipolar device having a second floating base region, a second emitter, and a second collector,
wherein said first floating base region and said second floating base region are common to said floating body region;
wherein said first collector is common to said second collector;
wherein at least one of said first bipolar device or second bipolar device maintains a state of said memory cell, and
wherein said transistor is usable to access said memory cell.
2. The semiconductor memory cell of claim 1 , wherein said state of said memory cell is stored in at least one of said first floating base region, said second floating base region or said floating body region.
3. The semiconductor memory cell of claim 1 , wherein said state of said memory cell is maintained through a back bias applied to said first and second collectors.
4. The semiconductor memory cell of claim 3 , wherein said back-bias applied to said first and second collectors is a constant voltage bias.
5. The semiconductor memory cell of claim 3 , wherein said back-bias applied to said first and second collectors is a periodic pulse of voltage.
6. The semiconductor memory cell of claim 3 , wherein said back bias results in at least two stable states.
7. The semiconductor memory cell of claim 1 , wherein said transistor is formed in a fin structure.
8. 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 transistor comprising a source region, a floating body region, a drain region, and a gate;
a first bipolar device having a first floating base region, a first emitter, and a first collector; and
a second bipolar device having a second floating base region, a second emitter, and a second collector;
wherein said first floating base region and said second floating base region are common to said floating body region;
wherein said first collector is common to said second collector; and
wherein at least one of said first bipolar device or second bipolar device maintains a state of said memory cell, wherein said transistor is usable to access said memory cell; and
wherein said first and second collectors are commonly connected to at least two of said memory cells.
9. The semiconductor memory array of claim 8 , wherein said state of said memory cell is stored in at least one of said first floating base region, said second floating base region, or said floating body region.
10. The semiconductor memory array of claim 8 , wherein a back bias applied to said first and second collectors maintains the state of said memory cells connected to said first and second collectors.
11. The semiconductor memory array of claim 10 , wherein said back-bias applied to said first and second collectors is a constant voltage bias.
12. The semiconductor memory array of claim 10 , wherein said back-bias applied to said first and second collectors is a periodic pulse of voltage.
13. The semiconductor memory array of claim 10 , wherein said back bias results in at least two stable states.
14. The semiconductor memory array of claim 8 , wherein said transistor is formed in a fin structure.
15. An integrated circuit comprising:
an array of semiconductor memory cells formed in a semiconductor substrate having at least one surface, the array comprising:
said semiconductor memory cells arranged in a matrix of rows and columns, wherein each said semiconductor memory cell includes:
a transistor comprising a source region, a floating body region, a drain region, and a gate;
a first bipolar device having a first floating base region, a first emitter, and a first collector; and
a second bipolar device having a second floating base region, a second emitter, and a second collector;
a first control circuit configured to provide electrical signals to said first and second collectors, and
a second control circuit configured to provide electrical signals to said transistor to access said memory cell;
wherein said first floating base region and said second floating base region are common to said floating body region;
wherein said first collector is common to said second collector;
wherein at least one of said first bipolar device and said second bipolar device maintains a state of said memory cell;
wherein said transistor is usable to access said memory cell;
wherein said first and second collectors are commonly connected to at least two of said memory cell.
16. The integrated circuit of claim 15 , wherein said first control circuit provides electrical signals to said first and second collectors to maintain the state of said memory cells connected to said first and second collectors.
17. The integrated circuit of claim 16 , wherein said electrical signals to said first and second collectors are constant voltage biases.
18. The integrated circuit of claim 16 , wherein said electrical signals to said first and second collectors are periodic pulses of voltage.
19. The integrated of claim 16 , wherein said electrical signals to said first and second collectors result in at least two stable states.
20. The integrated circuit of claim 15 , wherein said second control circuit provides electrical signals to said transistors to read the states of said memory cells.