Contacts for semiconductor devices
View Patent ↗A memory device includes a number of memory cells and a dielectric layer formed over the memory cells. The memory device also includes contacts formed in the dielectric layer and spacers formed adjacent the side surfaces of the contacts. The spacers may inhibit leakage currents from the contacts.
1. A method comprising:
forming a plurality of memory cells on a substrate of a memory device, each memory cell, of the plurality of memory cells, comprising a tunnel oxide layer formed on the substrate and a control gate electrode, wherein forming the plurality of memory cells includes etching completely at least the control gate electrode and the tunnel oxide layer that are disposed between each of the plurality of memory cells;
forming first spacers adjacent to a first memory cell of the plurality of memory cells, each of the first spacers being formed on one of opposite sides of the first memory cell, each of the first spacers including a silicon oxynitride;
forming second spacers adjacent to a second memory cell of the plurality of memory cells, each of the second spacers being formed on one of opposite sides of the second memory cell, each of the second spacers including a silicon oxynitride, wherein the first and second spacers are in direct contact with the substrate;
forming an interlayer dielectric layer over the plurality of memory cells, the first spacers, and the second spacers, the interlayer dielectric layer including a boro-phosphosilicate glass (BPSG) material or a phosphosilicate glass (PSG) material, the interlayer dielectric layer substantially contacting the first spacers, the second spacers, a top surface of the control gate electrode of the first memory cell, and a top surface of the control gate electrode of the second memory cell;
forming a contact hole, through the interlayer dielectric layer to reach at least the substrate, between the first memory cell and the second memory cell, a particular first spacer, of the first spacers, and a particular second spacer, of the second spacers, being adjacent to sidewalls of the contact hole;
subsequent to forming the contact hole, forming a third spacer adjacent to the particular first spacer and a fourth spacer adjacent to the particular second spacer, each of the third spacer and the fourth spacer comprising a dielectric with a height of the third spacer and a height of the fourth spacer being greater than a height of the first spacers and a height of the second spacers; and
forming a contact in the contact hole.
2. The method of claim 1 , wherein the third spacer and the fourth spacer substantially contact the substrate and the interlayer dielectric layer, and
wherein a width of the third spacer and a width of the fourth spacer each ranges from 50 Å to 400 Å.
3. The method of claim 1 , wherein a top surface of each of the first spacers is substantially co-planar with the top surface of the control gate electrode of the first memory cell, and
wherein a top surface of each of the second spacers is substantially co-planar with the top surface of the control gate electrode of the second memory cell.
4. The method of claim 1 , wherein the third spacer prevents charge leakage between the contact and the first memory cell, and
wherein the fourth spacer prevents charge leakage between the contact and the second memory cell.
5. The method of claim 1 , wherein a width of each of the first spacers ranges from about 50 Å to about 400 Å, and
wherein a width of each of the second spacers ranges from about 50 Å to about 400 Å.
6. The method of claim 1 , wherein a height of the third spacer ranges from about 4000 Å to about 8000 Å, and wherein a height of the fourth spacer ranges from about 4000 Å to about 8000 Å.
7. The method of claim 1 , wherein forming the plurality of memory cells comprises:
forming a first dielectric layer, of the first memory cell, on the substrate;
forming a charge storage layer, of the first memory cell, on the first dielectric layer;
forming a second dielectric layer, of the first memory cell, on the charge storage layer; and
forming the control gate electrode, of the first memory cell, on the second dielectric layer,
wherein the charge storage layer comprises polycrystalline silicon,
wherein the second dielectric layer comprises aluminum oxide or hafnium oxide, and
wherein the third spacer and the fourth spacer comprise a nitride.
8. A method comprising:
forming first spacers adjacent to a first memory cell and in direct contact with the substrate, the first memory cell being formed on a substrate of a memory device, each of the first spacers being formed on one of opposite sides of the first memory cell, a top surface of each of the first spacers being substantially co-planar with a top surface of a control gate electrode of the first memory cell;
forming second spacers adjacent to a second memory cell and in direct contact with the substrate, the second memory cell being formed on the substrate, each of the second spacers being formed on one of opposite sides of the second memory cell, a top surface of each of the second spacers being substantially co-planar with a top surface of a control gate electrode of the second memory cell, wherein forming the first and second memory cells includes forming the control gate and a tunnel oxide layer over the substrate and subsequently etching at least the control gate electrode and the tunnel oxide layer that are disposed between the first and second memory cells;
forming an interlayer dielectric layer over the first memory cell, the second memory cell, the first spacers, and the second spacers, the interlayer dielectric layer substantially contacting the first spacers, the second spacers, the top surface of the control gate electrode of the first memory cell, and the top surface of the control gate electrode of the second memory cell;
forming a contact hole, through the interlayer dielectric layer to at least reach the substrate, between the first memory cell and the second memory cell, one of the first spacers and one of the second spacers being adjacent to sidewalls of the contact hole;
subsequent to forming the contact hole, forming a third spacer adjacent to the one of the first spacers, the third spacer comprising a dielectric with a height of the third spacer being greater than a height of the first spacers;
forming a fourth spacer adjacent to the one of the second spacers, the fourth spacer comprising a dielectric with a height of the fourth spacer being greater than a height of the second spacers; and
forming a contact in the contact hole.
9. The method of claim 8 , wherein the control gate electrode, of the first memory cell, includes polycrystalline silicon, and
wherein the control gate electrode, of the second memory cell, includes polycrystalline silicon.
10. The method of claim 9 , wherein the interlayer dielectric layer comprises a boro-phsphosilicate glass (BPSG) material or a phosphosilicate glass (PSG) material.
11. The method of claim 8 , wherein the third spacer and the fourth spacer substantially contact the substrate and the interlayer dielectric layer, and
wherein a width of the third spacer and a width of the fourth spacer each ranges from 50 Å to 400 Å.
12. The method of claim 8 , wherein the third spacer prevents charge leakage between the contact and a charge storage layer of the first memory cell, and
wherein the fourth spacer prevents charge leakage between the contact and a charge storage layer of the second memory cell.
13. The method of claim 8 , wherein a height of the third spacer ranges from about 4000 Å to about 8000 Å, and
wherein a height of the fourth spacer ranges from about 4000 Å to about 8000 Å.
14. The method of claim 8 , wherein a width of each of the first spacers ranges from about 50 Å to about 400 Å, and
wherein a width of each of the second spacers ranges from about 50 Å to about 400 Å.
15. The method of claim 8 , wherein each of the first spacers includes a silicon oxide, a silicon nitride, or a silicon oxynitride, and
wherein each of the second spacers includes a silicon oxide, a silicon nitride, or a silicon oxynitride.
16. A method comprising:
forming first spacers adjacent to a memory cell, the memory cell being formed on a substrate of a memory device, each of the first spacers being formed on one of opposite sides of the memory cell and in direct contact with the substrate, a top surface of each of the first spacers being substantially co-planar with a top surface of a control gate electrode of the memory cell, wherein forming the memory cell includes forming the control gate electrode and a tunnel oxide layer over the substrate and subsequently etching completely at least the control gate electrode and the tunnel oxide layer that are disposed beyond the memory cell;
forming an interlayer dielectric layer over the memory cell and the first spacers, the interlayer dielectric layer substantially contacting:
the first spacers, and
the top surface of the control gate electrode of the first memory cell;
forming a contact hole through the interlayer dielectric layer to at least reach the substrate, one of the first spacers being adjacent to a sidewall of the contact hole;
subsequent to forming the contact hole, forming a second spacer adjacent to the one of the first spacers, the second spacer comprising a dielectric with a height of the second spacer being greater than a height of the first spacers, the second spacer substantially contacting the substrate and the interlayer dielectric layer; and
forming a contact in the contact hole.
17. The method of claim 16 , wherein the control gate electrode, of the memory cell, comprises polycrystalline silicon, and
wherein the interlayer dielectric layer comprises a boro-phsphosilicate glass (BPSG) material or a phosphosilicate glass (PSG) material.
18. The method of claim 16 , wherein the second spacer prevents charge leakage between the contact and a charge storage layer of the memory cell.
19. The method of claim 16 , wherein a width of each of the first spacers ranges from about 50 Å to about 400 Å, and
wherein each of the first spacers includes a silicon oxide, a silicon nitride, or a silicon oxynitride.
20. The method of claim 16 , wherein a height of the second spacer ranges from about 4000 Å to about 8000 Å, and
wherein a width of the second spacer ranges from 50 Å to 400 Å.