OTP cell with reversed MTJ connection
A one time programming (OTP) apparatus unit cell includes magnetic tunnel junctions (MTJs) with reversed connections for placing the MTJ in an anti-parallel resistance state during programming. Increased MTJ resistance in its anti-parallel resistance state causes a higher programming voltage which reduces programming time and programming current.
1. An anti-fuse memory, comprising:
an anti-fuse magnetic tunnel junction (MTJ) memory cell; and
a programming driver configured to drive the anti-fuse MTJ memory cell with a programming voltage, wherein the anti-fuse MTJ memory cell is configured to switch into an anti-parallel state in response to being driven with the programming voltage, and wherein the programming driver is further configured to drive the anti-fuse MTJ memory cell with the programming voltage so as to break down a dielectric barrier in the anti-fuse MTJ memory cell after the anti-fuse MTJ memory cell switches into the anti-parallel state.
2. The anti-fuse memory of claim 1 , further comprising:
a bit line coupled to a first terminal of the anti-fuse MTJ memory cell;
an access transistor coupled between a second terminal of the anti-fuse MTJ memory cell and ground;
wherein the bit line comprises an upper metal layer, and a free layer in the first memory cell is coupled to a lower metal layer that is coupled to the access transistor.
3. The anti-fuse memory of claim 1 , further comprising:
a bit line coupled to a first terminal of the anti-fuse MTJ memory cell;
an access transistor coupled between a second terminal of the anti-fuse MTJ memory cell and ground;
wherein the bit line is a lower metal layer, and a free layer in the anti-fuse MTJ memory cell is coupled to an upper metal layer that is coupled to the access transistor.
4. The anti-fuse memory of claim 2 , further comprising:
sense amplifier circuitry coupled to the bit line.
5. The anti-fuse memory of claim 1 , integrated in a mobile phone, a set top box, a music player, a video player, an entertainment unit, a navigation device, a computer, a hand-held personal communication systems (PCS) unit, a portable data unit, and/or a fixed location data unit.
6. A method of programming an anti-fuse magnetic tunnel junction (MTJ) memory cell, comprising:
applying a voltage to a bit line;
asserting a word line to switch on an access transistor;
switching a state of the anti-fuse MTJ memory cell to an anti-parallel (AP) state in response to the asserting of the word line and the applying of the voltage to the bit line; and
after switching the MTJ state to the anti-parallel state, breaking down a dielectric barrier layer of the anti-fuse MTJ memory cell in response to applying the voltage.
7. The method of claim 6 , further comprising coupling the access transistor to a fixed potential.
8. The method of claim 7 , comprising coupling the access transistor to a ground potential.
9. The method of claim 6 , further comprising coupling a programmable driver to the bit line.
10. The method of claim 6 , further comprising integrating the one time programmable cell into a mobile phone, a set top box, a music player, a video player, an entertainment unit, a navigation device, a computer, a hand-held personal communication systems (PCS) unit, a portable data unit, and/or a fixed location data unit.