Antifuse with a single silicon-rich silicon nitride insulating layer
View Patent ↗An antifuse is disclosed which has an electrically-insulating region sandwiched between two electrodes. The electrically-insulating region has a single layer of a non-hydrogenated silicon-rich (i.e. non-stoichiometric) silicon nitride SiN X with a nitrogen content X which is generally in the range of 0<X≦1.2, and preferably 0.5≦X≦1.2. The breakdown voltage V BD for the antifuse can be defined to be as small as a few volts for CMOS applications by controlling the composition and thickness of the SiN X layer. The SiN X layer thickness can also be made sufficiently large so that Poole-Frenkel emission will be the primary electrical conduction mechanism in the antifuse. Different types of electrodes are disclosed including electrodes formed of titanium silicide, aluminum and silicon. Arrays of antifuses can also be formed.
1. An antifuse, comprising:
an electrically-insulating region consisting of a single layer of non-hydrogenated silicon-rich silicon nitride (SiN X ) 10-50 nanometers thick with a nitrogen content X in the range 0<X≦1.2, and with an electrical breakdown voltage ≦10 Volts; and
electrodes above and below the electrically-insulating region, with each electrode being in physical contact with the electrically-insulating region to provide the electrical breakdown voltage to program the antifuse without heat being transferred from the electrodes to the electrically-insulating region prior to breakdown of the electrically-insulating region.
2. The antifuse of claim 1 wherein at least one of the electrodes comprises a metal or metal alloy.
3. The antifuse of claim 1 wherein the electrode below the electrically-insulating region comprises a metal silicide.
4. The antifuse of claim 3 wherein the metal silicide comprises titanium silicide.
5. The antifuse of claim 3 wherein the electrode above the electrically-insulating region comprises a metal selected from the group consisting of titanium, tungsten, aluminum, copper and alloys thereof.
6. The antifuse of claim 1 wherein at least one of the electrodes comprises silicon.
7. The antifuse of claim 1 wherein the nitrogen content X is in the range 0.5≦X≦1.2.
8. The antifuse of claim 1 wherein the electrical breakdown voltage is ≦5 Volts.
9. The antifuse of claim 1 wherein only a single voltage is applied across the electrodes to program the antifuse and to provide the electrical breakdown voltage.
10. An antifuse, comprising:
a first electrode formed on a silicon substrate;
a single insulating layer deposited over the first electrode, with the single insulating layer being in physical contact with the first electrode, and with the single insulating layer being 10-50 nanometers thick, and consisting of a silicon-rich silicon nitride having a composition SiN X with a nitrogen content X which provides an electrical breakdown voltage less than or equal to 10 Volts; and
a second electrode formed over the single insulating layer, with the single insulating layer being in physical contact with the second electrode, and with the first and second electrodes not being a source of heat to reduce the electrical breakdown voltage.
11. The antifuse of claim 10 wherein 0.5≦X≦1.2.
12. The antifuse of claim 10 further comprising an electrical isolation layer deposited over the silicon substrate and having an opening wherein the single insulating layer contacts the first electrode.
13. The antifuse of claim 10 wherein at least one of the first and second electrodes consists of silicon which is doped with an n-type dopant or with a p-type dopant.
14. The antifuse of claim 10 wherein at least one of the first and second electrodes comprises titanium.
15. The antifuse of claim 10 wherein the electrical breakdown voltage is ≦5 Volts.
16. The antifuse of claim 10 wherein only a single voltage is applied across the electrodes to program the antifuse and to provide the electrical breakdown voltage.
17. An array of antifuses formed on a silicon substrate, with each antifuse comprising:
an electrically-insulating region consisting of a single layer of non-hydrogenated silicon-rich silicon nitride (SiN X ) 10-50 nanometers thick with a nitrogen content X in the range of 0<X≦1.2, and with an electrical breakdown voltage ≦10 Volts; and
addressing electrodes above and below the electrically-insulating region and in physical contact therewith to program each antifuse with only a single voltage applied across all of the addressing electrodes for that antifuse.
18. The array of antifuses in claim 17 wherein the electrical breakdown voltage is ≦5 Volts.
19. The array of antifuses in claim 17 wherein the nitrogen content X is in the range 0.5≦X≦1.2.
20. The array of antifuses in claim 17 wherein the addressing electrodes below the electrically-insulating region comprise a metal silicide.
21. The array of antifuses in claim 20 wherein the addressing electrodes above the electrically-insulating region comprise tungsten.
22. The array of antifuses in claim 17 wherein at least one of the addressing electrodes comprises silicon.
23. The array of antifuses in claim 17 wherein the addressing electrodes do not heat the electrically-insulating region prior to breakdown of the electrically-insulating region.