Physical unclonable functions with copper-silicon oxide programmable metallization cells

1. A method of producing a PUF device, the method comprising:

providing an electrode;

subsequently depositing a layer of silicon oxide onto the electrode; and

subsequently depositing a copper film onto the layer of silicon oxide to form a copper electrode,

wherein the layer of silicon oxide is deposited by physical vapor deposition, wherein the physical vapor deposition optionally includes a sputtering step and/or an evaporation step, and

wherein the physical vapor deposition conditions produce a relatively low density layer of silicon oxide.

2. The method of claim 1 , wherein the copper film is about 20 nm to about 200 nm thick.

3. The method of claim 1 , wherein the deposited layer of silicon oxide is about 5 nm to about 100 nm thick.

4. The method of claim 1 , further comprising an annealing step at about 500° C. to about 600° C. for about 10 minutes to about 20 minutes in pure N 2 , N 2 /H 2 , or Ar gas.

5. The method of claim 1 , wherein the layer of silicon oxide is deposited by plasma enhanced chemical vapor deposition at about 100° C. to about 200° C.

6. The method of claim 5 , wherein the deposited layer of silicon oxide is less than or equal to 15 nm thick.

7. A method of generating a secure key comprising:

(a) providing an array comprising

a plurality of copper lines; and

a plurality of lines comprising W, Ni, Pt, TiN, TaN, TiW, or polycrystalline silicon, the plurality of lines positioned perpendicular to the plurality of copper lines;

wherein a plurality of PUF devices is formed at a plurality of intersections of the plurality of copper lines and the plurality of lines,

wherein each of the plurality of PUF devices comprise

a first copper electrode,

a second electrode, and

a layer of silicon oxide positioned directly between the first copper electrode and the second electrode,

(b) subsequently placing each of the plurality of PUF devices into an off state;

(c) subsequently applying a positive voltage to one of the plurality of copper lines and a negative voltage or a ground voltage to one of the plurality of lines, with all other lines floating;

(d) subsequently measuring a parameter of the PUF device at the intersection of the lines in step (c); and

(e) repeating the sequence defined by steps (b) through (d) for a different pair of intersecting lines in step (c).

8. The method of claim 7 , wherein the method further comprises between step (d) and step (e), applying a negative voltage or a ground voltage to the copper line in step (c) and a positive voltage to the one of the plurality of lines in step (c).

9. A method of producing a PUF device, the method comprising:

providing a copper electrode;

subsequently depositing a layer of silicon oxide onto the copper electrode; and

subsequently depositing a film of a second electrode material onto the layer of silicon oxide, and

wherein the layer of silicon oxide is deposited by physical vapor deposition, wherein the physical vapor deposition optionally includes a sputtering step and/or an evaporation step, and

wherein the physical vapor deposition conditions produce a relatively low density layer of silicon oxide.

10. The method of claim 9 , wherein the film is about 20 nm to about 200 nm thick.

11. The method of claim 9 , wherein the deposited layer of silicon oxide is about 5 nm to about 100 nm thick.

12. The method of claim 9 , further comprising an annealing step at about 500° C. to about 600° C. for about 10 minutes to about 20 minutes in pure N 2 , N 2 /H 2 , or Ar gas.

13. The method of claim 9 , wherein the layer of silicon oxide is deposited by plasma enhanced chemical vapor deposition at about 100° C. to about 200° C.

14. The method of claim 13 , wherein the deposited layer of silicon oxide is less than or equal to 15 nm thick.

15. A method of producing a PUF device, the method comprising:

providing an electrode;

subsequently depositing a layer of silicon oxide onto the electrode;

subsequently depositing a copper film onto the layer of silicon oxide to form a copper electrode; and

annealing at about 500° C. to about 600° C. for about 10 minutes to about 20 minutes in pure N 2 , N 2 /H 2 , or Ar gas, and

wherein the layer of silicon oxide is deposited by physical vapor deposition, wherein the physical vapor deposition optionally includes a sputtering step and/or an evaporation step.

16. A method of producing a PUF device, the method comprising:

providing a copper electrode;

subsequently depositing a layer of silicon oxide onto the copper electrode;

subsequently depositing a film of a second electrode material onto the layer of silicon oxide; and

annealing at about 500° C. to about 600° C. for about 10 minutes to about 20 minutes in pure N 2 , N 2 /H 2 , or Ar gas, and

wherein the layer of silicon oxide is deposited by physical vapor deposition, wherein the physical vapor deposition optionally includes a sputtering step and/or an evaporation step.