FinFET device and method of forming same
A method for forming a semiconductor device includes patterning a substrate to form a strip including a first semiconductor material, forming an isolation region along a sidewall of the strip, an upper portion of the strip extending above the isolation region, forming a dummy structure along sidewalls and a top surface of the upper portion of the strip, performing a first etching process on an exposed portion of the upper portion of the strip to form a first recess, the exposed portion of the strip being exposed by the dummy structure, after performing the first etching process, reshaping the first recess to have a V-shaped bottom surface using a second etching process, wherein the second etching process is selective to first crystalline planes having a first orientation relative to second crystalline planes having a second orientation, and epitaxially growing a source/drain region in the reshaped first recess.
1 . A device comprising:
a fin over a substrate, the fin comprising a first fin portion adjacent a second fin portion;
an isolation region adjacent the fin;
a gate structure along sidewalls of the fin and over a top surface of the fin;
a gate spacer laterally adjacent the gate structure;
an epitaxial source/drain region on a first sidewall of the first fin portion and a second sidewall of the second fin portion, the first sidewall having a first lower sidewall portion, a first upper sidewall portion and a first top sidewall portion that extends from the first upper sidewall portion to a top surface of the fin, the second sidewall having a second lower sidewall portion, a second upper sidewall portion and a second top sidewall portion that extends from the second upper sidewall portion to the top surface of the fin, wherein a first sidewall surface of the first lower sidewall portion is a first crystalline plane and a second sidewall surface of the second lower sidewall portion is a second crystalline plane, wherein the first sidewall surface faces the second sidewall surface, wherein the first crystalline plane is a different plane than the second crystalline plane, wherein the first sidewall surface in the first crystalline plane intersects the second sidewall surface in the second crystalline plane, wherein the first upper sidewall portion and the second upper sidewall portion are vertical and directly contact the epitaxial source/drain region; and
a lightly doped source/drain (LDD) region in an upper region of the fin, wherein a point where the first top sidewall portion adjoins the first upper sidewall portion is disposed at a bottom of the LDD region in a cross-sectional view.
2 . The device of claim 1 , wherein the first crystalline plane and the second crystalline plane are (111) or (110) planes.
3 . The device of claim 1 , wherein an angle between the first top sidewall portion of the first sidewall and an upper surface of the first fin portion is in a range between 45° and 90°.
4 . The device of claim 1 , wherein a width of the epitaxial source/drain region between the first top sidewall portion of the first sidewall and the second top sidewall portion of the second sidewall is less than a width of the epitaxial source/drain region between the first upper sidewall portion of the first sidewall and the second upper sidewall portion of the second sidewall.
5 . A device comprising:
a first fin and a second fin over a substrate;
an isolation region adjacent the first fin;
a gate structure along sidewalls of the first fin and over a top surface of the first fin;
a gate spacer laterally adjacent the gate structure;
an epitaxial region adjacent the first fin and the second fin, wherein a portion of the epitaxial region tapers to a V-shaped bottom, wherein the epitaxial region extends along a first sidewall surface of the first fin and a second sidewall surface of the second fin, the first sidewall surface intersecting the second sidewall surface, wherein the first sidewall surface comprises a first lower sidewall portion and a first upper sidewall portion, wherein the first lower sidewall portion is along a first crystalline plane, wherein the first lower sidewall portion intersects the first upper sidewall portion, wherein the first upper sidewall portion is substantially vertical, wherein a surface of the epitaxial region extending along the first upper sidewall portion is substantially vertical, and wherein the epitaxial region increases in width from the top surface of the first fin to a first position on the first sidewall surface and then decreases in width from a second position on the first sidewall surface to where the epitaxial region tapers to the V-shaped bottom; and
a lightly doped source/drain (LDD) region in an upper region of the first fin, wherein the first upper sidewall portion extends to a bottommost point of the LDD region in a cross-sectional view.
6 . The device of claim 5 , wherein the first crystalline plane is a (111) crystalline plane.
7 . The device of claim 5 , wherein the first sidewall surface comprises a first top sidewall portion extending from the first upper sidewall portion to an upper surface of the substrate, wherein the first top sidewall portion extends along a second crystalline plane.
8 . The device of claim 7 , wherein the second crystalline plane is a (111) crystalline plane.
9 . The device of claim 7 , wherein the first top sidewall portion has a vertical depth in a range between 1 nm and 30 nm.
10 . The device of claim 5 , wherein the first upper sidewall portion has a vertical depth in a range between 10 nm and 50 nm.
11 . The device of claim 5 , wherein a vertical distance between a top of the substrate and a bottom of the epitaxial region is in a range between 40 nm and 100 nm.
12 . The device of claim 5 , wherein the epitaxial region is laterally spaced apart from the gate structure by a first distance, wherein the first distance is in a range between 1 nm and 10 nm.
13 . The device of claim 5 , wherein the epitaxial region extends lower than a lower surface of the isolation region.
14 . The device of claim 5 , wherein the epitaxial region directly contacts the first upper sidewall portion.
15 . The device of claim 5 , wherein the epitaxial region from the top surface of the first fin to the V-shaped bottom ranges from 30 nm to 100 nm.
16 . The device of claim 5 , wherein the LDD region comprises a first portion and a second portion, and wherein a portion of the epitaxial region is between the first portion of the LDD region and the second portion of the LDD region.
17 . A device comprising:
a fin over a substrate;
an isolation region adjacent the fin;
a gate structure along sidewalls of the fin and over a top surface of the fin;
a gate spacer laterally adjacent the gate structure;
an epitaxial source/drain region in a recess in the fin, wherein the recess has a first sidewall surface and a second sidewall surface, each of the first sidewall surface and the second sidewall surface having a lower sidewall surface, a middle sidewall surface, and an upper sidewall surface, the middle sidewall surface extending from the lower sidewall surface to the upper sidewall surface, the lower sidewall surface being along a first crystalline plane, the middle sidewall surface being substantially vertical, and the upper sidewall surface extending along a second crystalline plane, wherein the epitaxial source/drain region directly contacts the middle sidewall surface, wherein a first portion of the epitaxial source/drain region contacting the upper sidewall surface for each of the first sidewall surface and the second sidewall surface at the top surface of the fin has a first width, and a second portion of the epitaxial source/drain region contacting the first sidewall surface and the second sidewall surface of an interface of the upper sidewall surface and the middle sidewall surface has a second width, wherein the first width is less than the second width; and
a lightly doped source/drain (LDD) region in an upper region of the fin, wherein the epitaxial source/drain region extends directly under the LDD region, and wherein the upper sidewall surface of the first sidewall surface extends to a bottommost point of the LDD region in a cross-sectional view.
18 . The device of claim 17 , wherein the first crystalline plane and the second crystalline plane are (111) or (110) planes.
19 . The device of claim 17 , wherein a width of the epitaxial source/drain region measured at an upper surface of the fin is in a range between 10 nm to 60 nm.
20 . The device of claim 17 , wherein the epitaxial source/drain region has a V-shaped bottom, wherein a bottom of the V-shaped bottom is laterally spaced apart from the gate structure by a distance between 1 nm and 25 nm.