SPLIT GATE NON-VOLATILE MEMORY CELLS, HV AND LOGIC DEVICES WITH FINFET STRUCTURES, AND METHOD OF MAKING SAME
A method of forming memory cells, high voltage devices and logic devices on fins of a semiconductor substrate's upper surface, and the resulting memory device formed thereby. The memory cells are formed on a pair of the fins, where the floating gate is disposed between the pair of fins, the word line gate wraps around the pair of fins, the control gate is disposed over the floating gate, and the erase gate is disposed over the pair of fins and partially over the floating gate. The high voltage devices include HV gates that wrap around respective fins, and the logic devices include logic gates that are metal and wrap around respective fins.
1 . A memory device, comprising:
a semiconductor substrate having an upper surface with a plurality of fins, wherein each of the fins extends upwardly and includes first and second side surfaces that oppose each other and that terminate in a top surface;
a memory cell formed on first and second fins of the plurality of fins, comprising:
a first channel region extending along the top and opposing side surfaces of the first fin between a source region of the first fin and a first drain region of the first fin,
a second channel region extending along the top and opposing side surfaces of the first fin between the first drain region of the first fin and a second drain region of the first fin,
a third channel region extending along the top and opposing side surfaces of the second fin between a source region of the second fin and a first drain region of the second fin,
a fourth channel region extending along the top and opposing side surfaces of the second fin between the first drain region of the second fin and a second drain region of the second fin,
a floating gate disposed between the first and second fins and extending along a first portion of the first channel region and a first portion of the third channel region,
a control gate that extends along and is insulated from the floating gate,
an erase gate having a first portion laterally adjacent to the floating gate and a second portion that is disposed over the floating gate, and
a word line gate that extends along the second channel region and the fourth channel region, wherein the word line gate extends along and is insulated from the first and second side surfaces and the top surface of the first and second fins;
a high voltage (HV) device formed on a third fin of the plurality of fins, comprising:
a HV channel region extending along the top and opposing side surfaces of the third fin between a HV source region of the third fin and a HV drain region of the third fin, and
a HV gate that extends along the HV channel region, wherein the HV gate extends along and is insulated from the first and second side surfaces and the top surface of the third fin; and
a logic device formed on a fourth fin of the plurality of fins, comprising:
a logic channel region extending along the top and opposing side surfaces of the fourth fin between a logic source region of the fourth fin and a logic drain region of the fourth fin, and
a logic gate that extends along the logic channel region, wherein the logic gate extends along and is insulated from the first and second side surfaces and the top surface of the fourth fin.
2 . The memory device of claim 1 , wherein the first portion of the erase gate extends along and is insulated from the top surfaces of the first and second fins.
3 . The memory device of claim 2 , wherein the first portion of the erase gate extends along and is insulated from a second portion of the first channel region and a second portion of the third channel region.
4 . The memory device of claim 1 , wherein the erase gate includes a notch facing an upper edge of the floating gate.
5 . The memory device of claim 1 , wherein the first and second fins are taller than the third and fourth fins.
6 . The memory device of claim 1 , wherein the logic gate includes a metal material, and wherein the logic gate is insulated from the first and second side surfaces and the top surface of the fourth fin by a high K insulation material.
7 . The memory device of claim 6 , wherein the floating gate, the word line gate, the control gate, the erase gate and the HV gate each include polysilicon material.
8 . A method of forming a memory device, comprising:
forming a plurality of fins in an upper surface of a semiconductor substrate, wherein each of the fins extends upwardly and includes first and second side surfaces that oppose each other and that terminate in a top surface; and
forming a memory cell on first and second fins of the plurality of fins, a high voltage (HV) device on a third fin of the plurality of fins, and a logic device on a fourth fin of the plurality of fins, by:
forming a floating gate between the first and second fins;
forming a control gate over and insulated from the floating gate;
forming a layer of conductive material over the first fin, the second fin, the third fin and the fourth fin;
selectively removing portions of the layer of conductive material, leaving:
a word line gate as a remaining portion of the layer of conductive material over the first and second fins,
an erase gate as a remaining portion of the layer of conductive material over the first and second fins, wherein the control gate is disposed between the word line gate and the erase gate,
a HV gate as a remaining portion of the layer of conductive material over the third fin, and
a dummy gate as a remaining portion of the layer of conductive material over the fourth fin;
forming a source region in the first fin adjacent the erase gate;
forming a drain region in the first fin adjacent the word line gate, wherein a channel region of the first fin extends along the top and opposing side surfaces of the first fin between the source region of the first fin and the drain region of the first fin;
forming a source region in the second fin adjacent the erase gate;
forming a drain region in the second fin adjacent the word line gate, wherein a channel region of the second fin extends along the top and opposing side surfaces of the second fin between the source region of the second fin and the drain region of the second fin;
forming source and drain regions in the third fin adjacent the HV gate, wherein a channel region of the third fin extends along the top and opposing side surfaces of the third fin between the source and drain regions of the third fin;
forming source and drain regions in the fourth fin adjacent the dummy gate, wherein a channel region of the fourth fin extends along the top and opposing side surfaces of the fourth fin between the source and drain regions of the fourth fin; and
replacing the dummy gate with a logic gate formed of metal.
9 . The method of claim 8 , wherein the layer of conductive material is polysilicon.
10 . The method of claim 8 , wherein:
the word line gate wraps around the first fin such that the word line gate extends along and is insulated from the top and opposing side surfaces of the first fin; and
the word line gate wraps around the second fin such that the word line gate extends along and is insulated from the top and opposing side surfaces of the second fin.
11 . The method of claim 10 , wherein:
the HV gate wraps around the third fin such that the HV gate extends along and is insulated from the top and opposing side surfaces of the third fin; and
the logic gate wraps around the fourth fin such that the logic gate extends along and is insulated from the top and opposing side surfaces of the fourth fin.
12 . The method of claim 8 , wherein:
the plurality of fins further includes fifth and sixth fins,
the fourth fin is disposed between the fifth and sixth fins,
the fourth fin is separated from the fifth fin by a first distance,
the fourth fin is separated from the sixth fin by the first distance,
the first fin is separated from the second fin by a second distance, and
the second distance is greater than the first distance.
13 . The method of claim 12 , wherein:
the plurality of fins further includes seventh and eighth fins,
the third fin is disposed between the seventh and eighth fins,
the third fin is separated from the seventh fin by a third distance,
the third fin is separated from the eighth fin by the third distance, and
the second distance is greater than the third distance.
14 . The method of claim 8 , wherein:
the erase gate wraps around the first fin such that the erase gate extends along and is insulated from the top and opposing side surfaces of the first fin; and
the erase gate wraps around the second fin such that the erase gate extends along and is insulated from the top and opposing side surfaces of the second fin.
15 . A method of forming a memory device, comprising:
forming a plurality of fins in an upper surface of a semiconductor substrate, wherein each of the fins extends upwardly and includes first and second side surfaces that oppose each other and that terminate in a top surface; and
forming a memory cell on first and second fins of the plurality of fins, a high voltage (HV) device on a third fin of the plurality of fins, and a logic device on a fourth fin of the plurality of fins, by:
forming a floating gate between the first and second fins;
forming a control gate over and insulated from the floating gate;
forming a layer of conductive material over the first fin, the second fin, the third fin and the fourth fin;
selectively removing portions of the layer of conductive material, leaving:
a word line gate as a remaining portion of the layer of conductive material over the first and second fins,
an erase gate as a remaining portion of the layer of conductive material over the first and second fins, wherein the control gate is disposed between the word line gate and the erase gate,
a HV gate as a remaining portion of the layer of conductive material over the third fin, and
a dummy gate as a remaining portion of the layer of conductive material over the fourth fin;
forming a source region in the first fin adjacent the erase gate;
forming a first drain region in the first fin adjacent the word line gate;
forming a second drain region in the first fin between the word line gate and the control gate, wherein a first channel region of the first fin extends along the top and opposing side surfaces of the first fin between the source region of the first fin and the second drain region of the first fin, and wherein a second channel region of the first fin extends along the top and opposing side surfaces of the first fin between the first drain region of the first fin and the second drain region of the first fin;
forming a source region in the second fin adjacent the erase gate;
forming a first drain region in the second fin adjacent the word line gate;
forming a second drain region in the second fin between the word line gate and the control gate, wherein a first channel region of the second fin extends along the top and opposing side surfaces of the second fin between the source region of the second fin and the second drain region of the second fin, and wherein a second channel region of the second fin extends along the top and opposing side surfaces of the second fin between the first drain region of the second fin and the second drain region of the second fin;
forming source and drain regions in the third fin adjacent the HV gate, wherein a channel region of the third fin extends along the top and opposing side surfaces of the third fin between the source and drain regions of the third fin;
forming source and drain regions in the fourth fin adjacent the dummy gate, wherein a channel region of the fourth fin extends along the top and opposing side surfaces of the fourth fin between the source and drain regions of the fourth fin; and
replacing the dummy gate with a logic gate formed of metal.
16 . The method of claim 15 , wherein the layer of conductive material is polysilicon.
17 . The method of claim 15 , wherein:
the word line gate wraps around the first fin such that the word line gate extends along and is insulated from the top and opposing side surfaces of the first fin; and
the word line gate wraps around the second fin such that the word line gate extends along and is insulated from the top and opposing side surfaces of the second fin.
18 . The method of claim 17 , wherein:
the HV gate wraps around the third fin such that the HV gate extends along and is insulated from the top and opposing side surfaces of the third fin; and
the logic gate wraps around the fourth fin such that the logic gate extends along and is insulated from the top and opposing side surfaces of the fourth fin.
19 . The method of claim 15 , wherein:
the plurality of fins further includes fifth and sixth fins,
the fourth fin is disposed between the fifth and sixth fins,
the fourth fin is separated from the fifth fin by a first distance,
the fourth fin is separated from the sixth fin by the first distance,
the first fin is separated from the second fin by a second distance,
the second distance is greater than the first distance.
20 . The method of claim 19 , wherein:
the plurality of fins further includes seventh and eighth fins,
the third fin is disposed between the seventh and eighth fins,
the third fin is separated from the seventh fin by a third distance,
the third fin is separated from the eighth fin by the third distance,
the second distance is greater than the third distance.