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 memory device, comprising:
a substrate;
a memory cell formed on the substrate, the memory cell comprising:
a first dielectric layer formed on the substrate,
a charge storage layer formed on the first dielectric layer,
a second dielectric layer formed on the charge storage layer, and
a control gate electrode formed on the second dielectric layer,
the control gate electrode including polycrystalline silicon;
a source region formed in the substrate;
a drain region formed in the substrate;
first spacers formed adjacent to the memory cell,
each of the first spacers being formed on one of opposite sides of the memory cell,
each of the first spacers including silicon oxynitride and substantially directly contacting the substrate,
a top surface of each of the first spacers being substantially co-planar with a top surface of the control gate electrode;
an interlayer dielectric layer formed over the memory cell and the first spacers,
the interlayer dielectric layer including a boro-phosphosilicate glass (BPSG) material or a phosphosilicate glass (PSG) material and substantially contacting:
the first spacers including the silicon oxynitride, and
the top surface of the control gate electrode;
a contact hole formed in the interlayer dielectric layer,
a selected first spacer, of the first spacers, forming a portion of a wall defining the contact hole;
a second spacer formed adjacent to the selected first spacer and on the wall defining the contact hole,
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,
the first spacers and the second spacer being formed over the source region or the drain region; and
a contact formed in the contact hole,
the second spacer preventing charge leakage between:
the contact, and
the charge storage layer and the control gate electrode; and
a conductive interconnect line formed over the interlayer dielectric layer and the contact.
2. The memory device of claim 1 , where the second spacer includes a nitride,
where a width of the second spacer ranges from about 50 Å to about 400 Å,
where a width of the first spacer ranges from about 50 Å to about 400 Å,
where a width of a portion of the contact ranges from about 400 Å to about 900 Å, and
where the memory device further comprises:
third spacers formed adjacent to another memory cell,
each of the third spacers being formed on one of opposite sides of the other memory cell,
the interlayer dielectric layer formed over the other memory cell and the third spacers,
the contact hole being formed between the memory cell and the other memory cell;
a fourth spacer formed on another wall, defining the contact hole, opposite the wall; and
another interlayer dielectric layer formed over the conductive interconnect line.
3. The memory device of claim 1 , where a width of each of the first spacers or the width of the second spacer is less than 300 Å.
4. The memory device of claim 1 , where the second spacer comprises a nitride.
5. The memory device of claim 1 , where the charge storage layer comprises silicon.
6. The memory device of claim 1 , where the charge storage layer comprises polycrystalline silicon, and
where the second dielectric layer comprises aluminum oxide or hafnium oxide.
7. The memory device of claim 1 , where the charge storage layer is to store charges representing at least two bits of data for the memory cell.
8. A non-volatile memory device, comprising:
a plurality of memory cells formed on a substrate;
a source region formed in the substrate;
a drain region formed in the substrate;
first spacers formed adjacent, respectively, to the plurality of memory cells,
each of the first spacers including silicon nitride and substantially contacting the substrate;
second spacers formed adjacent, respectively, to the plurality of memory cells,
each of the second spacers being formed opposite a corresponding first spacer of the first spacers,
each of the second spacers including silicon nitride and substantially contacting the substrate;
an interlayer dielectric layer formed 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 a top surface of a control gate electrode, including polycrystalline silicon, of each of the plurality of memory cells,
a top surface of each of the first spacers and a top surface of a corresponding second spacer, of the second spacers, being substantially co-planar with the top surface of the control gate electrode of a corresponding memory cell of the plurality of memory cells;
a contact hole formed, in the interlayer dielectric layer, between two memory cells of the plurality of memory cells,
one of the first spacers forming a portion of a wall defining the contact hole,
a third spacer formed adjacent to the one of the first spacers and on the wall defining the contact hole,
a height of the third spacer being greater than a height of the one of the first spacers,
each of the one of the first spacers and the third spacer being formed over the source region or the drain region, and
the interlayer dielectric layer contacting:
a portion of the one of the first spacers, and
a portion of the third spacer; and
a contact formed in the contact hole,
the third spacer preventing charge leakage between the contact and at least one of the two memory cells.
9. The non-volatile memory device of claim 8 , where a width of the one of the first spacers ranges from about 50 Å to about 400 Å,
where a width of the third spacer ranges from about 50 Å to about 400 Å,
where a width of a portion of the contact ranges from about 400 Å to about 900 Å, and
where the non-volatile memory device further comprises:
a conductive interconnect line formed over and substantially contacting the interlayer dielectric layer and the contact;
another interlayer dielectric layer formed over the conductive interconnect line;
a metal layer deposited in a trench that is formed in the other interlayer dielectric layer; and
a conductive layer formed over the other interlayer dielectric layer and the metal layer.
10. The non-volatile memory device of claim 8 , where the third spacer comprises a nitride.
11. The non-volatile memory device of claim 8 , where each of the plurality of memory cells includes a charge storage element to store charges representing two bits of information, and
where the third spacer prevents charge leakage between the contact and the charge storage element of the at least one of the two memory cells.
12. A memory device, comprising:
a plurality of memory cells formed on a substrate;
first spacers formed, respectively, on a first side surface of the plurality of memory cells and second spacers formed, respectively, on a second side opposite the first side surface of the plurality of memory cells,
the first spacers and the second spacers including silicon nitride or silicon oxynitride, and
the first spacers and the second spacers, formed on the plurality of memory cells, substantially contacting the substrate;
a dielectric layer formed over the plurality of memory cells, the first spacers, and the second spacers,
the dielectric layer including a boro-phosphosilicate glass (BPSG) material or a phosphosilicate glass (PSG) material and substantially contacting:
a top surface of a control gate electrode, including polycrystalline silicon, of each of the plurality of memory cells,
the first spacers, and
the second spacers,
a top surface of each of the first spacers and a top surface of each of the second spacers being substantially co-planar with a top surface of the control gate electrode of a corresponding memory cell of the plurality of memory cells;
a plurality of contact holes formed in the dielectric layer between the plurality of memory cells,
the first spacers or the second spacers forming portions of respective ones of a plurality of walls defining the plurality of contact holes;
third spacers formed:
adjacent to the first spacers or the second spacers, and
on the plurality of walls defining the plurality of contact holes,
a height of each of the third spacers being greater than a height of each of the first spacers and a height of each of the second spacers,
the third spacers including silicon nitride or silicon oxynitride; and
a plurality of contacts,
each of the plurality of contacts being formed in a respective one of the plurality of contact holes,
each of the third spacers being formed between:
a respective one of the plurality of contacts, and
the dielectric layer.
13. The memory device of claim 12 , where each contact, of the plurality of contacts, substantially contacts a portion of a bit line coupled to a source region of one of the plurality of memory cells and a drain region of an adjacent one of the plurality of memory cells.
14. The memory device of claim 12 , where the third spacers include dielectric spacers.
15. The memory device of claim 12 , where a width of each of the first spacers and a width of each of the second spacers range from about 50 Å to about 400 Å,
where a width of each of the third spacers ranges from about 50 Å to about 400 Å,
where a width of each of the plurality of contacts ranges from about 400 Å to about 900 Å, and
where the memory device further comprises:
a conductive interconnect line formed over and substantially in direct contact with the dielectric layer and the plurality of contacts;
an interlayer dielectric layer formed over the conductive interconnect line;
a metal layer deposited in a trench that is formed in the interlayer dielectric layer; and
a conductive layer formed over the interlayer dielectric layer and the metal layer.
16. The memory device of claim 12 , where each of the plurality of memory cells stores charges representing at least two bits of information, and
where each of the plurality of memory cells substantially contacts the substrate.
17. The memory device of claim 12 , where each of the third spacers is formed to a height ranging from about 4000 Å to about 8000 Å.
18. The memory device of claim 15 , where the interlayer dielectric layer includes a BPSG material or a PSG material.
19. The memory device of claim 6 , further comprising:
another interlayer dielectric layer formed over the conductive interconnect line,
the other interlayer dielectric layer including a BPSG material or a PSG material;
a metal layer deposited in a trench that is formed in the other interlayer dielectric layer;
a conductive layer formed over the other interlayer dielectric layer and the metal layer; and
another dielectric layer formed over the conductive layer.
20. The non-volatile memory device of claim 9 , where the other interlayer dielectric layer includes a BPSG material or a PSG material.