SRAM memory cell protected against current or voltage spikes

1. A memory cell protected against current or voltage spikes, comprising:

a group of redundant data storage nodes for the storage of information comprising at least a first pair of complementary nodes and a second pair of complementary nodes; and

a circuit that restores information to its initial state following a current or voltage spike modifying the information in one of the complementary nodes using the information stored in another one of the complementary nodes;

wherein the complementary nodes of the first pair are associated with first and second same channel type connected transistors implanted within a first well of a first conductivity type and wherein the complementary nodes of the second pair are associated with third and fourth same channel type connected transistors implanted within a second well of the same first conductivity type, and wherein the first and second wells are located on opposite sides from one another within a region of a substrate defining the boundary of a single memory cell.

2. The memory cell according to claim 1 , wherein corresponding nodes of each pair of complementary nodes are separated by a distance that is greater than one micron.

3. The memory cell according to claim 1 , further comprising a well of a second conductivity type opposite the first conductivity type positioned between the separated wells of the first conductivity type and within the boundary of the single memory cell so as to define junctions isolating the two pairs of complementary nodes from each other.

4. A memory cell protected against current or voltage spikes, comprising:

a group of redundant data storage nodes for the storage of information in a single memory cell comprising at least a first pair of complementary nodes and a second pair of complementary nodes; and

a circuit that restores information in the single memory cell to its initial state following a current or voltage spike modifying the information in one of the complementary nodes using the information stored in another one of the complementary nodes, wherein the means for restoring comprises four groups of transistors whose purpose is to control the voltage level of four respective nodes in the group of redundant data storage nodes; and

wherein a first pair of same channel type connected transistors associated with the first pair of complementary nodes are implanted in a first well of a first conductivity type and a second pair of same channel type connected transistors associated with the second pair of complementary nodes are implanted in a second well, separate from the first well, also of the first conductivity type.

5. The memory cell according to claim 4 , wherein a group of transistors is associated with each redundant data storage node, each group of transistors comprises a first and a second transistor, the first transistor being an MOS transistor of p type and the second transistor being an MOS transistor of n type, the source and the drain of the first transistor being respectively connected to a power supply voltage and to the drain of the second transistor, the source of the second transistor being connected to ground.

6. The memory cell according to claim 5 , wherein the gate and the drain of the first transistor of one of the group of transistors are connected to the drain of the first transistor and to the gate of the second transistor of another of the group of transistors, respectively.

7. The memory cell according to claim 5 , wherein the drain of the first transistor and the gate of the second transistor of one of the groups of transistors are connected to the gate and to the drain of the first transistor of another of the groups of transistors, respectively.

8. The memory cell according to claim 7 , wherein the gate and the drain of the first transistor of the one group of transistors are connected to the drain of the first transistor and to the gate of the second transistor of the another group of transistors, respectively.

9. The memory cell according to claim 5 , wherein the second transistors of a first and second groups of transistors are disposed within the first well of p type conductivity and in that the second transistors of a third and fourth groups of transistors are disposed within the second well of p type conductivity, the first and second p-type conductivity wells being separated by a well of n type within which the first transistors of the groups of transistors are implanted.

10. The memory cell according to claim 2 wherein the group of redundant data storage nodes comprise a true data storage node in each pair and a false data storage node in each pair, and wherein the true data storage nodes in the two pairs are separated by the distance, and further wherein the false data storage nodes in the two pairs are separated by the distance.

11. The memory cell according to claim 1 wherein the first and third transistors providing true nodes have a distance of separation that is greater than one micron and the second and fourth transistors providing false nodes have a distance of separation that is greater than one micron.

12. A memory cell protected against current or voltage spikes, comprising:

a group of redundant data storage nodes for the storage of information in at least a first and second pair of complementary nodes provided for a single memory cell, wherein the group of redundant data storage nodes comprise a pair of true data storage nodes at the gate terminals of first and second transistors and a pair of false data storage nodes at the gate terminals of third and fourth transistors, the first through fourth transistors being of a same channel type; and

a circuit that restores information to its initial state following a current or voltage spike modifying the information in one of the complementary nodes using the information stored in another one of the complementary nodes;

wherein the first and second transistors for the true data storage nodes are implanted in different wells of a first conductivity type, and

wherein the third and fourth transistors for the false data storage nodes are implanted in different wells of the first conductivity type, the first and third transistors being in one well of the first conductivity type and the second and fourth transistors being in another well of the first conductivity type; and

wherein the different wells are on opposite sides from one another within a region of a substrate defining the boundary of the single memory cell.

13. The memory cell according to claim 12 wherein the first and third transistors are implanted in a first well of the first conductivity type and the second and fourth transistors are implanted in a second well of the first conductivity type, the cell further including at least one additional transistor implanted in a well of a second conductivity type, wherein the well of the second conductivity type is positioned in the substrate between the first and second wells of the first conductivity type.

14. A memory cell protected against current or voltage spikes, comprising:

a group of redundant data storage nodes for the storage of information in at least a first and second pair of complementary nodes for a single memory cell, wherein the group of redundant data storage nodes comprise first and second transistors associated with a pair of true data storage nodes and third and fourth transistors associated with a pair of false data storage nodes, the first through fourth transistors being of a same channel type; and

a circuit that restores information to its initial state following a current or voltage spike modifying the information in one of the complementary nodes using the information stored in another one of the complementary nodes;

wherein the nodes of each pair are on opposite sides from one another within a region of a substrate defining the boundary of the single memory cell; and

wherein the first and second transistors are formed in the region in two different wells on opposite sides of a center area within the boundary and wherein the third and fourth transistors are formed in the region in the two different wells on opposite sides of the center area.

15. The memory cell according to claim 14 wherein the first and third transistors are formed in a first well of a first conductivity type and the second and fourth transistors are formed in a second well also of the first conductivity type, and wherein the center area comprises a well of a second conductivity type in which additional transistors are implanted, those additional transistors being connected to the first through fourth transistors.

16. The memory cell according to claim 15 wherein the first conductivity type is p-type and the second conductivity type is n-type.

17. The memory cell according to claim 14 wherein the first and third transistors for the pair of true data storage nodes are separated by a distance of at least 1 micron.

18. The memory cell according to claim 14 wherein the second and fourth transistors for the pair of false data storage nodes are separated by a distance of at least 1 micron.