Deuterated film encapsulation of nonvolatile charge trap memory device
A nonvolatile charge trap memory device with deuterium passivation of charge traps and method of manufacture. Deuterated gate layer, deuterated gate cap layer and deuterated spacers are employed in various combinations to encapsulate the device with deuterium sources proximate to the interfaces within the gate stack and on the surface of the gate stack where traps may be present.
1. A nonvolatile charge trap memory device, comprising:
a gate stack between a source and drain region, the gate stack comprising:
a tunneling layer, a trapping layer, a blocking layer, a gate layer; and
a deuterated gate cap layer;
a gate stack spacer adjacent to a sidewall of the gate stack; and
an interlayer dielectric layer on the gate stack and the gate stack spacer, the gate cap layer having a higher deuterium concentration at an interface with the gate layer than at an interface with the interlayer dielectric layer.
2. The nonvolatile charge trap memory device of claim 1 , wherein the deuterated gate cap layer comprises deuterated silicon nitride.
3. The nonvolatile charge trap memory device of claim 1 , wherein the gate stack spacer is deuterated.
4. The nonvolatile charge trap memory device of claim 3 , wherein the deuterated gate stack spacer includes a first dielectric layer and a second dielectric layer on the first dielectric layer and at least one of the first dielectric layer and the second dielectric layer comprises deuterated silicon nitride.
5. The nonvolatile charge trap memory device of claim 4 , wherein the first dielectric layer comprises deuterated silicon nitride and the second dielectric layer is non-deuterated.
6. The nonvolatile charge trap memory device of claim 1 , wherein the gate layer is deuterated and has a concentration of deuterium greater near an interface with the blocking layer than near the interface with the gate cap layer.
7. The nonvolatile charge trap memory device of claim 6 , wherein the gate layer is deuterated silicon.
8. The nonvolatile charge trap memory device of claim 6 , wherein the deuterated gate layer comprises a lower concentration of deuterium than does the deuterated gate cap layer.
9. The nonvolatile charge trap memory device of claim 1 , wherein the deuterated gate cap layer has a higher deposited deuterium concentration at the interface with the gate layer than at the interface with the interlayer dielectric layer.
10. A nonvolatile charge trap memory device, comprising:
a gate stack between a source and drain region, the gate stack comprising:
a tunneling layer, a trapping layer, a blocking layer, a gate layer, and a deuterated gate cap layer;
a deuterated gate stack spacer adjacent to a sidewall of the gate stack, wherein the deuterated gate stack spacer includes a first dielectric layer and a second dielectric layer on the first dielectric layer and at least one of the first dielectric layer and the second dielectric layer comprises deuterated silicon nitride; and
an interlayer dielectric layer on the gate stack and on the gate stack spacer,
wherein a deuterium concentration throughout the thickness of the deuterated silicon
nitride layer has a gradient with a higher deuterium concentration proximate to the sidewall of the gate stack than proximate to the interlayer dielectric layer.
11. The nonvolatile charge trap memory device of claim 10 , wherein the deuterium concentration in the gate stack is highest in the deuterated gate cap layer.
12. The nonvolatile charge trap memory device of claim 10 , wherein the deuterated gate cap layer has a higher concentration of deuterium than the blocking layer.
13. The nonvolatile charge trap memory device of claim 10 , wherein the deuterated gate stack spacer has a higher concentration of deuterium than the interlayer dielectric layer.
14. The nonvolatile charge trap memory device of claim 10 , wherein the at least one of the first dielectric layer and the second dielectric layer comprising deuterated silicon nitride proximate to the gate stack has a deuterium concentration that is substantially the same as the deuterium concentration in a region proximate to the interlayer dielectric.