3D flash memory cells which discourage cross-cell electrical tunneling
First Claim
1. A 3-d flash memory cell, the 3-d flash memory cell comprising:
- a stack of silicon oxide slabs, wherein a tungsten slab selected from a plurality of tungsten slabs is disposed between each neighboring pair of vertically neighboring silicon oxide slabs in a memory hole of the 3-d flash memory cell, wherein the plurality of tungsten slabs are recessed relative to the silicon oxide slabs away from the memory hole to form a plurality of recesses;
a plurality of compound floating gates each comprising a polysilicon buffer portion and a high work function metal portion, wherein the plurality of compound floating gates are disposed entirely within the plurality of recesses, wherein the stack of silicon oxide slabs extends beyond the plurality of compound floating gates into the memory hole; and
a high-k dielectric liner disposed between the stack of silicon oxide slabs and the plurality of tungsten slabs, wherein the high-k dielectric liner is further disposed between the plurality of compound floating gates and the tungsten slabs, and wherein the high-k dielectric liner comprises aluminum oxide.
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Abstract
3-d flash memory cells and methods of manufacture are described. The devices and methods recess a compound floating gate in between the silicon oxide slabs which reduces the quantum probability of electron tunneling between vertically adjacent storage cells. The devices and methods further include a high work function nanocrystalline metal in the compound floating gate. A polysilicon buffer layer forms a portion of the compound floating gate. The polysilicon buffer layer allows the high work function nanocrystalline metal to be selectively deposited. The polysilicon buffer layer further protects the high work function nanocrystalline metal from oxidation with the gate oxide subsequently formed on the other side.
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Citations
20 Claims
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1. A 3-d flash memory cell, the 3-d flash memory cell comprising:
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a stack of silicon oxide slabs, wherein a tungsten slab selected from a plurality of tungsten slabs is disposed between each neighboring pair of vertically neighboring silicon oxide slabs in a memory hole of the 3-d flash memory cell, wherein the plurality of tungsten slabs are recessed relative to the silicon oxide slabs away from the memory hole to form a plurality of recesses; a plurality of compound floating gates each comprising a polysilicon buffer portion and a high work function metal portion, wherein the plurality of compound floating gates are disposed entirely within the plurality of recesses, wherein the stack of silicon oxide slabs extends beyond the plurality of compound floating gates into the memory hole; and a high-k dielectric liner disposed between the stack of silicon oxide slabs and the plurality of tungsten slabs, wherein the high-k dielectric liner is further disposed between the plurality of compound floating gates and the tungsten slabs, and wherein the high-k dielectric liner comprises aluminum oxide. - View Dependent Claims (2, 3, 4, 5, 6, 14, 15, 16)
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7. A 3-d flash memory cell, the 3-d flash memory cell comprising:
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a stack of alternating silicon oxide slabs and tungsten slabs comprising a plurality of the silicon oxide slabs, wherein the tungsten slabs are recessed compared to the silicon oxide slabs to form a plurality of recesses between vertically neighboring silicon oxide slabs; a floating gate disposed entirely within at least one of the plurality of recesses, wherein the floating gate comprises a polysilicon buffer and a high work function metal and wherein the polysilicon buffer is horizontally disposed between the high work function metal and one of the tungsten slabs, wherein neither the polysilicon buffer nor the high work function metal extends horizontally outside the plurality of recesses; a high-k dielectric liner disposed between the polysilicon buffer and one of the tungsten slabs, wherein the high-k dielectric liner is further disposed between the silicon oxide slabs and the tungsten slab, wherein the high-k dielectric liner comprises an oxygen-containing material in contact with the polysilicon buffer; and a barrier layer disposed between the high-k dielectric liner and the tungsten slab. - View Dependent Claims (8, 9, 10, 11, 12, 13, 17, 18, 19, 20)
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Specification