Deuterated film encapsulation of nonvolatile charge trap memory device
Nonvolatile charge trap memory devices with deuterium passivation of charge traps and methods of forming the same are described. In one embodiment, the device includes a channel formed from a semiconducting material overlying a surface on a substrate connecting a source and a drain of the memory device. A gate stack overlies the channel, the gate stack comprising a tunneling layer, a trapping layer, a blocking layer, a gate layer; and a deuterated gate cap layer. The gate cap layer has a higher deuterium concentration at an interface with the gate layer than at surface of the gate cap layer distal from the gate layer. In certain embodiments, the channel comprises polysilicon or recrystallized polysilicon. Other embodiments are also described.
1. A memory device comprising:
a channel formed from a semiconducting material overlying a surface on a substrate connecting a source and a drain of the memory device;
a gate stack overlying the channel, the gate stack comprising a tunneling layer, a trapping layer, a blocking layer, a gate layer; and a deuterated gate cap layer,
wherein the gate cap layer has a higher deuterium concentration at an interface with the gate layer than at surface of the gate cap layer distal from the gate layer.
2. The memory device of claim 1 wherein the channel comprises polysilicon.
3. The memory device of claim 1 wherein the channel comprises a silicon nanowire.
4. The memory device of claim 1 wherein the deuterated gate cap layer comprises deuterated silicon nitride.
5. The memory device of claim 1 wherein the gate layer is deuterated.
6. The memory device of claim 5 wherein the gate layer has a concentration of deuterium greater near an interface with the blocking layer than near the interface with the gate cap layer.
7. The memory device of claim 5 wherein the gate layer is deuterated silicon.
8. The memory device of claim 5 wherein the deuterated gate layer comprises a lower concentration of deuterium than does the deuterated gate cap layer.
9. The memory device of claim 1 wherein the trapping layer comprises a multi-layer trapping layer including a substantially trap free, oxygen-rich, first oxynitride layer on the tunneling layer and a trap dense, oxygen-lean, second oxynitride layer on the first oxynitride layer.
10. The memory device of claim 9 wherein the multi-layer trapping layer further comprises an anti-tunneling layer separating the first oxynitride layer from the second oxynitride layer.
11. A method of fabricating a nonvolatile charge trap memory device, comprising:
forming on a substrate a channel from a semiconducting material overlying a surface of the substrate, the channel connecting a source and a drain of the memory device; and
forming a gate stack overlying the channel, the gate stack comprising a tunneling layer, a trapping layer, a blocking layer, a gate layer; and a deuterated gate cap layer,
wherein the gate cap layer has a higher deuterium concentration at an interface with the gate layer than at surface of the gate cap layer distal from the gate layer.
12. The method of claim 11 wherein forming the channel from a semiconducting material comprises forming the channel from polysilicon.
13. The method of claim 11 , 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.