Method of forming a device with planar split gate non-volatile memory cells, planar HV devices, and FinFET logic devices on a substrate
A method of forming a device on a silicon substrate having first, second and third areas includes recessing an upper substrate surface in the first and third areas, forming an upwardly extending silicon fin in the second area, forming first source, drain and channel regions in the first area, forming second source, drain and channel regions in the fin, forming third source, drain and channel regions in the third area, forming a floating gate over a first portion of the first channel region using a first polysilicon deposition, forming an erase gate over the first source region and a device gate over the third channel region using a second polysilicon deposition, and forming a word line gate over a second portion of the first channel region, a control gate over the floating gate, and a logic gate over the second channel region using a metal deposition.
1. A method of forming a device, comprising:
providing a substrate of silicon having first, second and third areas;
recessing an upper surface of the substrate in the first area and an upper surface of the substrate in third area, relative to an upper surface of the substrate in the second area;
removing portions of the substrate in the second area to form an upwardly extending fin of silicon having a pair of side surfaces extending up and terminating at a top surface;
forming a first source region and a first drain region in the first area, wherein the first source region and the first drain region define a first channel region of the substrate extending therebetween;
forming a second source region and a second drain region in the fin of silicon to define a second channel region of the substrate extending therebetween along the top surface and the pair of side surfaces of the fin of silicon;
forming a third source region and a third drain region in the third area, wherein the third source region and the third drain region define a third channel region of the substrate extending therebetween;
forming a floating gate disposed over and insulated from a first portion of the first channel region of the substrate using a first polysilicon deposition;
forming an erase gate disposed over and insulated from the first source region and a device gate disposed over and insulated from the third channel region of the substrate using a second polysilicon deposition different from the first polysilicon deposition; and
forming a word line gate disposed over and insulated from a second portion of the first channel region, a control gate disposed over and insulated from the floating gate, and a logic gate disposed over and insulated from the second channel region of the substrate, using a metal deposition;
wherein the removing of the portions of the substrate to form the fin of silicon is performed after the recessing
wherein after the recessing and before the removing, the method further comprising:
forming trenches extending into the substrate in the first and third areas;
forming insulation material in the first and third areas; and
planarizing an upper surface of the insulation material;
wherein the trenches are filled with the insulation material after the planarizing.
2. The method of claim 1 , wherein the control gate has a first portion disposed vertically over the floating gate, and a second portion disposed laterally adjacent to the floating gate.
3. The method of claim 1 , wherein the control gate is disposed vertically over and insulated from a top surface of the floating gate, and is disposed laterally adjacent to and insulated from a pair of side surfaces of the floating gate, such that the control gate wraps around the top surface and the pair of side surfaces of the floating gate.
4. The method of claim 1 , wherein the removing of the portions of the substrate to form the fin of silicon is performed before the forming of the control gate, the erase gate, the device gate, the word line gate and the logic gate.
5. The method of claim 1 , wherein the removing of the portions of the substrate in the second area to form the fin of silicon comprises:
forming a layer of first material over the second area;
forming trenches in the first material;
forming spacers of second material along sidewalls of the trenches in the first material;
removing the first material; and
performing an etch of the substrate around the spacers of the second material to form the fin of silicon.
6. The method of claim 1 , wherein the logic gate is disposed vertically over and insulated from the top surface of the fin of silicon, and is disposed laterally adjacent to and insulated from the pair of side surfaces of the fin of silicon, such that the logic gate wraps around the top surface and the pair of side surfaces of the fin of silicon.
7. The method of claim 1 , wherein the forming of the word line gate and the logic gate comprises:
performing a third polysilicon deposition, different from the first and second polysilicon depositions, to form a first block of polysilicon material over and insulated from the second portion of the first channel region and a second block of polysilicon material over and insulated from the second channel region;
replacing the first block of polysilicon material with a first block of metal using a polysilicon etch and the metal deposition; and
replacing the second block of polysilicon material with a second block of metal using the polysilicon etch and the metal deposition.
8. The method of claim 7 , wherein:
the replacing the first block of polysilicon material comprises forming a layer of high K material under the first block of metal; and
the replacing the second block of polysilicon material comprises forming the layer of high K material under the second block of metal.
9. A method of forming a device, comprising:
providing a substrate of silicon having first, second and third areas;
recessing an upper surface of the substrate in the first area and an upper surface of the substrate in third area, relative to an upper surface of the substrate in the second area;
removing portions of the substrate in the second area to form an upwardly extending fin of silicon having a pair of side surfaces extending up and terminating at a top surface;
forming a first source region and a first drain region in the first area, wherein the first source region and the first drain region define a first channel region of the substrate extending therebetween;
forming a second source region and a second drain region in the fin of silicon to define a second channel region of the substrate extending therebetween along the top surface and the pair of side surfaces of the fin of silicon;
forming a third source region and a third drain region in the third area, wherein the third source region and the third drain region define a third channel region of the substrate extending therebetween;
forming a floating gate disposed over and insulated from a first portion of the first channel region of the substrate using a first polysilicon deposition;
forming an erase gate disposed over and insulated from the first source region and a device gate disposed over and insulated from the third channel region of the substrate using a second polysilicon deposition different from the first polysilicon deposition; and
forming a word line gate disposed over and insulated from a second portion of the first channel region, a control gate disposed over and insulated from the floating gate, and a logic gate disposed over and insulated from the second channel region of the substrate, using a metal deposition;
wherein the word line gate is insulated from the second portion of the first channel region by at least a layer of high K material, and the logic gate is insulated from the second channel region by at least the layer of high K material, and the control gate is insulated from the floating gate by at least the layer of high K material.
10. The method of claim 9 , wherein the word line gate is further insulated from the second portion of the first channel region by an oxide layer, and the logic gate is further insulated from the second channel region by the oxide layer.
11. The method of claim 9 , wherein the control gate is further insulated from the floating gate by an insulation layer that comprises a first oxide, a nitride and a second oxide sublayers.
12. A method of forming a device, comprising:
providing a substrate of silicon having first, second and third areas;
recessing an upper surface of the substrate in the first area and an upper surface of the substrate in third area, relative to an upper surface of the substrate in the second area;
removing portions of the substrate in the second area to form an upwardly extending fin of silicon having a pair of side surfaces extending up and terminating at a top surface;
forming a first source region and a first drain region in the first area, wherein the first source region and the first drain region define a first channel region of the substrate extending therebetween;
forming a second source region and a second drain region in the fin of silicon to define a second channel region of the substrate extending therebetween along the top surface and the pair of side surfaces of the fin of silicon;
forming a third source region and a third drain region in the third area, wherein the third source region and the third drain region define a third channel region of the substrate extending therebetween;
forming a floating gate disposed over and insulated from a first portion of the first channel region of the substrate using a first polysilicon deposition;
forming an erase gate disposed over and insulated from the first source region and a device gate disposed over and insulated from the third channel region of the substrate using a second polysilicon deposition different from the first polysilicon deposition; and
forming a word line gate disposed over and insulated from a second portion of the first channel region, a control gate disposed over and insulated from the floating gate, and a logic gate disposed over and insulated from the second channel region of the substrate, using a metal deposition:
wherein the forming of the word line gate and the logic gate comprises:
performing a third polysilicon deposition, different from the first and second polysilicon depositions, to form a first block of polysilicon material over and insulated from the second portion of the first channel region and a second block of polysilicon material over and insulated from the second channel region;
replacing the first block of polysilicon material with a first block of metal using a polysilicon etch and the metal deposition; and
replacing the second block of polysilicon material with a second block of metal using the polysilicon etch and the metal deposition;
wherein the forming of the control gate comprises:
performing a fourth polysilicon deposition, different from the first, second and third polysilicon depositions, to form a third block of polysilicon disposed over and insulated from the floating gate; and
replacing the third block of polysilicon with a third block of metal using the polysilicon etch and the metal deposition.
13. The method of claim 12 , wherein:
the replacing the third block of polysilicon comprises forming a layer of high K material under the third block of metal.
14. A The device, comprising:
a substrate of silicon having first, second and third areas, wherein:
an upper surface in the first area is planar,
an upper surface in the third area is planar,
an upper surface in the second area includes an upwardly extending fin of silicon that includes a pair of side surfaces extending up and terminating at a top surface, and
the upper surface in the first area and the upper surface in the third area are recessed below the top surface of the fin of silicon;
a memory cell in the first area, comprising:
first source and first drain regions formed in the first area with a first channel region of the substrate extending therebetween,
a floating gate of polysilicon disposed over and insulated from a first portion of the first channel region,
a word line gate of metal disposed over and insulated from a second portion of the first channel region,
a control gate of metal disposed vertically over and insulated from a top surface of the floating gate, the control gate of metal is disposed laterally adjacent to and insulated from a pair of side surfaces of the floating gate, such that the control gate of metal wraps around the top surface and the pair of side surfaces of the floating gate, and
an erase gate of polysilicon disposed over and insulated from the first source region;
a high voltage device in the third area, comprising:
third source and third drain regions formed in the third area with a third channel region of the substrate extending therebetween, and
a device gate of polysilicon disposed over and insulated from the third channel region; and
a logic device in the second area, comprising:
second source and second drain regions formed in the fin of silicon with a second channel region of the substrate extending therebetween along the top surface and the pair of side surfaces of the fin of silicon, and
a logic gate disposed vertically over and insulated from the top surface of the fin of silicon, the logic gate disposed laterally adjacent to and insulated from the pair of side surfaces of the fin of silicon, such that the logic gate wraps around the top surface and the pair of side surfaces of the fin of silicon;
wherein the word line gate is insulated from the second portion of the first channel region by at least a layer of high K material, and the logic gate is insulated from the second channel region by at least the layer of high K material, and the control gate is insulated from the floating gate by at least the layer of high K material.
15. The device of claim 14 , wherein the word line gate is further insulated from the second portion of the first channel region by an oxide layer, and the logic gate is further insulated from the second channel region by the oxide layer.
16. The device of claim 14 , wherein the control gate is further insulated from the floating gate by an insulation layer that comprises a first oxide, a nitride and a second oxide sublayers.