Semiconductor device having nitridated oxide layer and method therefor
View Patent ↗A semiconductor device includes a substrate ( 12 ), a first insulating layer ( 14 ) over a surface of the substrate ( 12 ), a layer of nanocrystals ( 13 ) over a surface of the first insulating layer ( 14 ), a second insulating layer ( 15 ) over the layer of nanocrystals ( 13 ). A nitriding ambient is applied to the second insulating layer ( 15 ) to form a barrier to further oxidation when a third insulating layer ( 22 ) is formed over the substrate ( 12 ). The nitridation of the second insulating layer ( 15 ) prevents oxidation or shrinkage of the nanocrystals and an increase in the thickness of the first insulating layer 14 without adding complexity to the process flow for manufacturing the semiconductor device ( 10 ).
1. A method for forming a semiconductor device comprising:
providing a semiconductor substrate;
forming a first insulating layer over a surface of the semiconductor substrate;
forming a layer of nanocrystals over a surface of the first insulating layer;
forming a second insulating layer over the layer of nanocrystals;
applying a nitriding ambient to the second insulating layer;
selectively removing portions of the layer of nanocrystals and the first and second insulating layers to expose the surface of the semiconductor substrate; and
forming a third insulating layer over the exposed surface of the semiconductor substrate.
2. The method of claim 1 , further comprising forming a patterned polysilicon layer over the second insulating layer, wherein the patterned polysilicon layer forms gate electrodes for a plurality of non-volatile memory cells.
3. The method of claim 2 , wherein the patterned polysilicon layer is formed over the third insulating layer to form gate electrodes for a plurality of transistors.
4. The method of claim 1 , wherein applying the nitriding ambient to the second insulating layer comprises applying the nitriding ambient using plasma nitridation.
5. The method of claim 1 , wherein applying the nitriding ambient to the second insulating layer comprises applying the nitriding ambient using thermal nitridation.
6. The method of claim 1 , wherein applying nitrogen to the second insulating layer comprises applying the nitriding ambient using ion implantation.
7. The method of claim 1 , further comprising:
forming a fourth insulating layer over the second insulating layer; and applying a second nitriding ambient to the fourth insulating layer.
8. The method of claim 1 , wherein forming the second insulating layer comprises forming the second insulating layer by forming a laminate of insulating layers.
9. The method of claim 8 , wherein applying the nitriding ambient to the second insulating layer comprises applying the nitriding ambient to each layer of the laminate of insulating layers after each layer of the laminate of insulating layers is formed.
10. The method of claim 1 , further comprising annealing the semiconductor device after applying the nitriding ambient to the second insulating layer.
11. The method of claim 1 , wherein the nitriding ambient is applied to the second insulating layer after the portions of the layer of nanocrystals are selectively removed.
12. The method of claim 1 , wherein the nitriding ambient includes one or more of ammonia, nitrous oxide, atomic nitrogen, or other nitrogen compounds.