Method and system for providing contact to a first polysilicon layer in a flash memory device
View Patent ↗A method and system for providing at least one contact in a flash memory device is disclosed. The flash memory device includes a plurality of gate stacks and at lease one component including a polysilicon layer as a top surface. The method and system further include forming a silicide on the top surface of the polysilicon layer and providing an insulating layer covering the plurality of gate stacks, the at least one component and the silicide. The method and system also include etching the insulating layer to provide at least one contact hole. The insulating layer etching step uses the silicide as an etch stop layer to ensure that the insulating etching step does not etch through the polysilicon layer. The method and system also include filling the at least one contact hole with a conductor.
1. A flash memory device, comprising:
a substrate;
a source region and a drain region formed in the substrate;
a gate stack disposed on the substrate that at least partially overlaps each of the source region and the drain region, the gate stack having a first combination of layers that includes an uppermost layer and a second layer immediately adjacent the uppermost layer in a stack direction of the gate stack; and
a component disposed on the substrate that does not overlap either of the source region or the drain region, the component having a second combination of layers different from the first combination of layers,
wherein an uppermost layer of the second combination of layers is a first silicide layer, and
wherein the second layer of the first combination of layers is a second silicide layer.
2. The flash memory device of claim 1 , further comprising:
a field oxide region formed in the substrate adjacent to one of the source region or the drain region,
wherein the component is on, and in contact with, the field oxide region.
3. The flash memory device of claim 1 , wherein the second combination of layers includes fewer layers than the first combination of layers.
4. The flash memory device of claim 1 , wherein:
the first combination of layers includes an insulating layer as the uppermost layer.
5. The flash memory device of claim 4 , further comprising:
a first contact hole that is disposed through the insulating layer of the gate stack and that terminates at the second silicide layer of the gate stack.
6. The flash memory device of claim 5 , further comprising a second contact hole disposed immediately above one of the source region or the drain region.
7. The flash memory device of claim 5 , further comprising:
a third silicide layer formed immediately on one of the source region or the drain region; and
a second contact hole disposed above the one of the source region or the drain region that terminates at the third silicide layer.
8. The flash memory device of claim 4 , wherein the insulating layer is a SiON layer.
9. The flash memory device of claim 1 , further comprising spacers disposed along sidewalls of only the gate stack.
10. The flash memory device of claim 9 , further comprising an oxide layer disposed between the substrate and a combination of the gate stack and the spacers.
11. The flash memory device of claim 1 , wherein the first silicide layer is not overlapped by any other layers of the component.
12. The flash memory device of claim 1 , wherein the uppermost layer of the first combination of layers is a single layer.