Multi-time programmable memory
View Patent ↗Methods and systems that extend the capability of fuse elements, anti-fuse elements, and combinations thereof to enable multi-time programmable memory elements are provided. Accordingly, significantly reduced area requirements and control circuitry complexity of memory elements is enabled. The provided methods and systems can be used in non-volatile memory storage, and are suitable for use in system on chip (SoC) products.
1. A method for programming a memory element comprised of a poly diode anti-fuse coupled in parallel with a poly fuse, comprising:
applying a first current between a first terminal and a second terminal of the memory element, wherein the first current is configured to open the poly fuse to transition the memory element from an initial programming state to a first programming state, and wherein a first impedance of the memory element in the first programming state is higher than an initial impedance of the memory element in the initial programming state.
2. The method of claim 1 , wherein the memory element is equivalent to a short circuit between the first terminal and the second terminal in the initial programming state.
3. The method of claim 1 , wherein the first impedance of the memory element is provided by the poly diode anti-fuse in the first programming state.
4. The method of claim 1 , further comprising:
applying a voltage across the first terminal and the second terminal, wherein the voltage is configured to highly reverse bias the poly diode anti-fuse to transition the memory element from the first programming state to a second programming state.
5. The method of claim 4 . wherein a second impedance of the memory element in the second programming state is lower than the first impedance of the memory element in the first programming state.
6. The method of claim 5 , wherein the second impedance of the memory element is provided by the poly diode anti-fuse in the second programming state.
7. The method of claim 4 , further comprising:
applying a second current between the first terminal and the second terminal, wherein the second current is configured to open an n-p junction of the poly diode anti-fuse to transition the memory element from the second programming state to a third programming state.
8. The method of claim 7 , wherein a third impedance of the memory element in the third programming state is higher than the second impedance of the memory element in the second programming state.
9. The method of claim 7 , wherein the memory element is equivalent to an open circuit between the first terminal and the second terminal in the third programming state.
10. A memory element having an initial programming state and a first programming state, comprising:
a first terminal and a second terminal;
a poly diode anti-fuse coupled to the first terminal and the second terminal; and
a poly fuse,
wherein, in the initial programming state, the poly diode anti-fuse is coupled in parallel with the poly fuse to provide an initial impedance of the memory element, and
wherein, in the first programming state, the poly fuse is open to provide a first impedance of the memory element, different than the initial impedance of the memory element.
11. The memory element of claim 10 , wherein the first impedance of the memory element is higher than the initial impedance of the memory element.
12. The memory element of claim 10 , wherein the poly diode anti-fuse includes an N-doped region, coupled to the first terminal, and a P-doped region, coupled to the second terminal.
13. The memory element of claim 10 , wherein the poly fuse includes a silicide layer.
14. The memory element of claim 10 , wherein the memory element further has a second programming state, and wherein, in the second programming state, the poly diode anti-fuse is in a highly reverse biased state.
15. The memory element of claim 14 , wherein a second impedance of the memory element in the second programming state is lower than the first impedance of the memory element in the first programming state.
16. The memory element of claim 14 , wherein the memory element further has a third programming state, and wherein, in the third programming state, an n-p junction of the poly diode anti-fuse is open.
17. The memory element of claim 16 , wherein a third impedance of the memory element in the third programming state is higher than the second impedance of the memory element in the second programming state.
18. A method for programming a memory element comprised of a poly diode anti-fuse coupled in parallel with a poly fuse, comprising:
applying a first current between a first terminal and a second terminal of the memory element, wherein the first current is configured to open the poly fuse to transition the memory element from an initial programming state to a first programming state; and
applying a voltage across the first terminal and the second terminal, wherein the voltage is configured to highly reverse bias the poly diode anti-fuse to transition the memory element from the first programming state to a second programming state.
19. The method of claim 18 , further comprising:
applying a second current between the first terminal and the second terminal, wherein the second current is configured to open an n-p junction of the poly diode anti-fuse to transition the memory element from the second programming state to a third programming state.
20. The method of claim 18 , wherein the poly diode anti-fuse includes an N-doped region, coupled to the first terminal, and a P-doped region, coupled to the second terminal, and wherein the poly fuse includes a silicide layer.