FinFET structure and method for manufacturing thereof
Present disclosure provides a FinFET structure, including a substrate, a fin protruding from the substrate, including a first portion and a second portion below the first portion, the second portion includes a lighter-doped region and a heavier-doped region adjacent to the lighter-doped region, wherein the first portion includes a first dopant concentration of a dopant, and the heavier-doped region includes a second dopant concentration of the dopant, the second dopant concentration is greater than the first dopant concentration, a gate over the fin, wherein the second portion of the fin is below a bottom surface of the gate, and an insulating layer over the substrate and proximal to the second portion of the fin, wherein at least a first portion of the insulating layer includes a third dopant concentration of the dopant, the third dopant concentration is greater than the first dopant concentration.
1 . A FinFET structure, comprising:
a substrate;
a fin protruding from the substrate, comprising a first portion and a second portion below the first portion, the second portion comprises a lighter-doped region and a heavier-doped region adjacent to the lighter-doped region, wherein the first portion comprises a first dopant concentration of a dopant, and the heavier-doped region comprises a second dopant concentration of the dopant, the second dopant concentration is greater than the first dopant concentration;
a gate over the fin, wherein the second portion of the fin is below a bottom surface of the gate; and
an insulating layer over the substrate and proximal to the second portion of the fin, wherein at least a first portion of the insulating layer comprises a third dopant concentration of the dopant, the third dopant concentration is greater than the first dopant concentration, an upper boundary of the first portion of the insulating layer is below the heavier-doped region of the second portion of the fin, and the first portion of the insulating layer interfaces with the substrate.
2 . The FinFET structure of claim 1 , wherein the heavier doped region is above the lighter-doped region.
3 . The FinFET structure of claim 1 , wherein a sidewall of the first portion of the insulating layer is in contact with the substrate.
4 . The FinFET structure of claim 1 , further comprising a high-k dielectric layer between a sidewall of the first portion of the fin and the gate.
5 . The FinFET structure of claim 4 , wherein a sidewall of the second portion of the fin is free from coverage of the high-k dielectric layer.
6 . The FinFET structure of claim 1 , wherein the heavier-doped region is at a position below a bottom surface of the gate.
7 . The FinFET structure of claim 1 , wherein the insulating layer comprises a second portion adjacent to the first portion, wherein the second portion of the insulating layer comprises a fourth dopant concentration of the dopant, the fourth dopant concentration is less than the third dopant concentration.
8 . The FinFET structure of claim 1 , wherein the third dopant concentration is greater than the second dopant concentration.
9 . The FinFET structure of claim 1 , wherein a difference between a dopant concentration at a top of the lighter-doped region and a dopant concentration at a bottom of the lighter-doped region is less than 5%.
10 . A FinFET structure, comprising:
a substrate;
an insulating layer over the substrate, wherein a first portion of the insulating layer comprises a first dopant concentration of a dopant, and the first portion of the insulating layer interfaces with the substrate;
a fin protruding from the substrate, comprising a first portion and a second portion below the first portion, wherein a first section of the second portion of the fin has a highest dopant concentration of the dopant among the fin, the first portion of the fin is above a top surface of the insulating layer, the second portion of the fin is at a position below the top surface of the insulating layer, the first section of the second portion of the fin comprising a second dopant concentration of the dopant, the first portion of the fin comprises a dopant concentration less than the first dopant concentration, and an upper boundary of the first portion of the insulating layer is below the first section of the second portion of the fin; and
a gate over the fin.
11 . The FinFET structure of claim 10 , wherein the first section of the second portion of the fin is proximal to a top of the second portion of the fin.
12 . The FinFET structure of claim 10 , wherein the second dopant concentration is greater than 1E19/cm 3 .
13 . The FinFET structure of claim 10 , wherein the fin further comprises a second section below the first section, the second section of the second portion of the fin comprises a third dopant concentration of the dopant, wherein the third dopant concentration is less than the second dopant concentration.
14 . The FinFET structure of claim 10 , wherein the insulating layer comprises a second portion adjacent to the first portion, wherein the second portion of the insulating layer comprises a fourth dopant concentration of the dopant, the fourth dopant concentration is less than the first dopant concentration.
15 . A FinFET structure, comprising:
a substrate;
a fin protruding from the substrate, comprising:
a first portion, wherein the first portion comprises a first dopant concentration of a dopant;
a second portion below the first portion, wherein the second portion comprises a second dopant concentration of a dopant, wherein the second dopant concentration is greater than the first dopant concentration; and
a third portion below the second portion, wherein the third portion comprises a third dopant concentration of a dopant;
a gate over the fin, wherein the second portion of the fin is below a bottom surface of the gate; and
an insulating layer over the substrate and proximal to the second portion of the fin, wherein the insulating layer comprises:
a first part, comprising a fourth dopant concentration of the dopant, wherein an upper boundary of the first part of the insulating layer is below the second portion of the fin, wherein the fourth dopant concentration is greater than the first dopant concentration, and a lower boundary of the first part of the insulating layer coincides a lower boundary of the insulating layer; and
a second part adjacent to the first part, comprising a fifth dopant concentration of the dopant, wherein the fourth dopant concentration is greater than the fifth dopant concentration.
16 . The FinFET structure of claim 15 , wherein the second dopant concentration is greater than the third dopant concentration.
17 . The FinFET structure of claim 15 , wherein the first part of the insulating layer is below the second part of the insulating layer.
18 . The FinFET structure of claim 15 , wherein a portion of the third portion of the fin is laterally surrounded by the first part of the insulating layer.
19 . The FinFET structure of claim 15 , wherein a portion of the second portion of the fin is laterally surrounded by the second part of the insulating layer.
20 . The FinFET structure of claim 15 , wherein an upper boundary of the second part of the insulating layer coincides an upper boundary of the insulating layer.