One-time-programmable (OTP) implementation using magnetic junctions
Various embodiments of the present application are directed towards a one-time-programmable (OTP) implementation using magnetic junctions. In some embodiments, an array comprises multiple magnetic junctions in multiple columns and multiple rows, and the magnetic junctions comprise a first magnetic junction and a second magnetic junction. The first and second magnetic junctions comprise individual top ferromagnetic elements and individual bottom ferromagnetic elements, and further comprise individual barrier elements between the top and bottom ferromagnetic elements. A first barrier element of the first magnetic junction electrically separates first top and bottom ferromagnetic elements of the first magnetic junction. A second barrier element of the second magnetic junction has undergone breakdown, such that it has defects defining a leakage path between second top and bottom ferromagnetic elements of the second magnetic junction. The broken-down state corresponds to a one-time programmed state and is not susceptible to high-temperature change, even at small sizes.
1. An integrated chip comprising:
an array comprising a plurality of magnetic junctions in a plurality of columns and a plurality of rows, wherein the plurality of magnetic junctions comprises a first magnetic junction, second magnetic junction, and a third magnetic junction, and wherein the first and second magnetic junctions comprise individual top ferromagnetic elements and individual bottom ferromagnetic elements, and further comprise individual barrier elements between the top and bottom ferromagnetic elements; and
an access transistor directly under the third magnetic junction and electrically separated from the third magnetic junction;
wherein a first barrier element of the first magnetic junction electrically separates first top and bottom ferromagnetic elements of the first magnetic junction, and wherein a second barrier element of the second magnetic junction comprises defects defining a leakage path between second top and bottom ferromagnetic elements of the second magnetic junction.
2. The integrated chip according to claim 1 , wherein the first magnetic junction is offset from an edge of the array and the second magnetic junction is at an edge of the array.
3. The integrated chip according to claim 1 , further comprising:
a second access transistor having a first source/drain electrically coupled to the second bottom ferromagnetic element of the second magnetic junction; and
a pair of conductive lines extending along a column of the array in which the second magnetic junction is located, wherein the conductive lines are respectively and electrically coupled to a second source/drain of the second access transistor and the second top ferromagnetic element of the second magnetic junction.
4. The integrated chip according to claim 3 , further comprising:
a third access transistor electrically coupled in parallel with the access transistor.
5. The integrated chip according to claim 1 , wherein the first and second magnetic junctions have the same width.
6. The integrated chip according to claim 1 , wherein the first barrier element of the first magnetic junction has a top surface that is flat, and wherein the second barrier element of the second magnetic junction has a top surface that is curved.
7. The integrated chip according to claim 1 , wherein the third magnetic junction is in the same column of the array as the second magnetic junction.
8. An integrated chip comprising:
an array comprising a plurality of magnetic junctions in a plurality of columns and a plurality of rows, wherein the plurality of magnetic junctions comprises a first magnetic junction, a second magnetic junction, and a third magnetic junction, and wherein the first and second magnetic junctions comprise individual top ferromagnetic elements and individual bottom ferromagnetic elements, and further comprise individual barrier elements between the top and bottom ferromagnetic elements;
a reference circuit configured to generate a reference current by averaging individual currents flowing across the first and second magnetic junctions; and
a sense amplifier configured to compare the reference current to a read current flowing across the third magnetic junction;
wherein a first barrier element of the first magnetic junction electrically separates first top and bottom ferromagnetic elements of the first magnetic junction, and wherein a second barrier element of the second magnetic junction comprises defects defining a leakage path between second top and bottom ferromagnetic elements of the second magnetic junction.
9. The integrated chip according to claim 8 , wherein the third magnetic junction comprises a third top ferromagnetic element and a third bottom ferromagnetic element, and further comprises a third barrier element between the third top and bottom ferromagnetic elements, and wherein the third top ferromagnetic element comprises defects defining a leakage path between the third top and bottom ferromagnetic elements.
10. The integrated chip according to claim 8 , wherein the third magnetic junction comprises a third top ferromagnetic element and a third bottom ferromagnetic element, and further comprises a third barrier element between the third top and bottom ferromagnetic elements, and wherein the third barrier element electrically separates the third top and bottom ferromagnetic elements.
11. The integrated chip according to claim 8 , wherein the first magnetic junction is offset from an edge of the array and the second magnetic junction is at an edge of the array.
12. The integrated chip according to claim 8 , wherein the first and second magnetic junctions have the same width.
13. The integrated chip according to claim 8 , wherein the first barrier element of the first magnetic junction has a top surface that is flat, and wherein the second barrier element of the second magnetic junction has a top surface that is curved.
14. The integrated chip according to claim 8 , further comprising:
an access transistor having a first source/drain electrically coupled to the second bottom ferromagnetic element of the second magnetic junction; and
a pair of conductive lines extending along a column of the array in which the second magnetic junction is located, wherein the conductive lines are respectively and electrically coupled to a second source/drain of the access transistor and the second top ferromagnetic element of the second magnetic junction.
15. A method for reading a memory array, the method comprising:
providing an array comprising multiple magnetic junctions in a plurality of rows and a plurality of columns, wherein the magnetic junctions comprise individual top ferromagnetic elements and individual bottom ferromagnetic elements, and further comprise individual barrier elements between the top and bottom ferromagnetic elements;
generating a reference current by averaging a first current through a first magnetic junction of the array and a second current through a second magnetic junction of the array; and
comparing a read current through a third magnetic junction in the array to the reference current to sense a state of the third magnetic junction,
wherein a barrier element of the first magnetic junction electrically separates top and bottom ferromagnetic elements of the first magnetic junction, and wherein a barrier element of the second magnetic junction comprises defects defining a leakage path between top and bottom ferromagnetic elements of the second magnetic junction.
16. The method according to claim 15 , wherein the top and bottom ferromagnetic elements of the first magnetic junction have parallel magnetizations.
17. The method according to claim 15 , wherein the top and bottom ferromagnetic elements of the first magnetic junction have anti-parallel magnetizations.
18. The method according to claim 15 , wherein a barrier element of the third magnetic junction electrically separates top and bottom ferromagnetic elements of the third magnetic junction.
19. The method according to claim 15 , wherein a barrier element of the third magnetic junction comprises defects defining a leakage path between top and bottom ferromagnetic elements of the third magnetic junction.
20. The method according to claim 15 , further comprising:
biasing a word line extending along a row of the array to select the row, wherein the second magnetic junction is in the row; and
biasing a bit line extending along a column of the array to generate the second current at a source line extending along the column, wherein the second magnetic junction is in the column.