Memory device with multi-layered charge storage stack
An integrated circuit structure includes a plurality of gate layers, a laterally stacked multi-layered memory structure, and a vertical channel layer. The gate layers laterally extend above the substrate and spaced apart from each other. The laterally stacked multi-layered memory structure extends upwardly above the substrate and through the gate layers and including a blocking layer, a charge storage stack, and a tunneling layer. The charge storage stack is on the blocking layer and including a first silicon nitride layer, a second silicon nitride layer, and a silicon oxynitride layer sandwiched between the first and second silicon nitride layers. The tunneling layer is on the charge storage stack. The vertical channel layer is on the laterally stacked multi-layered memory structure.
1. An integrated circuit (IC) structure, comprising:
a plurality of gate layers laterally extending above a substrate and spaced apart from each other;
a laterally stacked multi-layered memory structure extending upwardly above the substrate and through the gate layers and comprising:
a blocking layer;
a charge storage stack on the blocking layer and comprising a first silicon nitride layer, a second silicon nitride layer, and a silicon oxynitride layer sandwiched between the first and second silicon nitride layers, wherein the first silicon nitride layer and the second nitride layer are symmetrically arranged with respect to the silicon oxynitride layer, and have substantially the same thickness; and
a tunneling layer on the charge storage stack; and
a vertical channel layer on the laterally stacked multi-layered memory structure.
2. The IC structure of claim 1 , wherein the first silicon nitride layer has a greater nitrogen atomic concentration than the second silicon nitride layer.
3. The IC structure of claim 2 , wherein the first silicon nitride layer is in contact with the blocking layer.
4. The IC structure of claim 1 , wherein the first silicon nitride layer has a less refractive index than the second silicon nitride layer.
5. The IC structure of claim 1 , wherein the first silicon nitride layer has a refractive index in a range from about 2.00 to about 2.03, and the second silicon nitride layer has a refractive index in a range from about 2.07 to about 2.10.
6. The IC structure of claim 1 , wherein the silicon oxynitride layer has a less refractive index than the first and second silicon nitride layers.
7. The IC structure of claim 1 , wherein the silicon oxynitride layer has a refractive index in a range from about 1.52 to about 1.65.
8. The IC structure of claim 1 , wherein the silicon oxynitride layer has a thinner thickness than the first and second silicon nitride layers.
9. The IC structure of claim 1 , wherein the silicon oxynitride layer has a greater oxygen atomic concentration than the first and second silicon nitride layers.
10. The IC structure of claim 1 , wherein the first and second silicon nitride layers are free of oxygen.