Vertical inverter formation on stacked field effect transistor (SFET)
Embodiments of the present invention are directed to stacked field effect transistors (SFETs) having integrated vertical inverters. In a non-limiting embodiment, a first nanosheet is vertically stacked over a second nanosheet. A common gate is formed around a channel region of the first and second nanosheets. A top source or drain region is formed in direct contact with the first nanosheet and a bottom source or drain region is formed in direct contact with the second nanosheet. A first portion of the top source or drain region is shorted to a first portion of the bottom source or drain region to define a common source or drain region. A second portion of the top source or drain region is electrically coupled to a second portion of the bottom source or drain region in series through the first nanosheet, the common source or drain region, and the second nanosheet.
1 . A method for forming a semiconductor device, the method comprising:
forming a first nanosheet vertically stacked over a second nanosheet;
forming a common gate around a channel region of the first nanosheet and a channel region of the second nanosheet;
forming a top source or drain region in direct contact with the first nanosheet; and
forming a bottom source or drain region in direct contact with the second nanosheet;
wherein a first portion of the top source or drain region is shorted to a first portion of the bottom source or drain region via a direct epitaxy contact growth of the first portion of the top source or drain region on a surface of the first portion of the bottom source or drain region to define a common source or drain region; and
wherein a second portion of the top source or drain region is electrically coupled to a second portion of the bottom source or drain region in series through the first nanosheet, the common source or drain region, and the second nanosheet.
2 . The method of claim 1 , further comprising:
forming a first nanosheet stack comprising the first nanosheet and one or more additional first nanosheets; and
forming a second nanosheet stack comprising the second nanosheet and one or more additional second nanosheets.
3 . The method of claim 2 , wherein the semiconductor device comprises a stacked field effect transistor.
4 . The method of claim 3 , wherein the stacked field effect transistor comprises a complementary stacked field effect transistor comprising an nFET and a pFET.
5 . The method of claim 4 , wherein the first nanosheet stack defines a portion of one of the nFET and the pFET and the second nanosheet stack defines a portion of the other one of the nFET and the pFET.
6 . The method of claim 5 , further comprising forming a middle dielectric isolation structure between the first nanosheet and the second nanosheet, the middle dielectric isolation structure in direct contact with the common source or drain region.
7 . The method of claim 6 , wherein the top source or drain region comprises a first doping type and the bottom source or drain region comprises a second doping type opposite the first doping type.
8 . The method of claim 1 , wherein a first sidewall of the first nanosheet is coplanar to a first sidewall of the second nanosheet, and wherein a second sidewall of the first nanosheet is recessed with respect to a second sidewall of the second nanosheet.
9 . The method of claim 1 , further comprising forming a bottom source or drain contact on a surface of the bottom source or drain region.
10 . The method of claim 9 , further comprising forming an isolation structure between the bottom source or drain contact and the top source or drain region, wherein a portion of the isolation structure is between the bottom source or drain contact and the common gate.
11 . A semiconductor device comprising:
a first nanosheet vertically stacked over a second nanosheet;
a common gate formed around a channel region of the first nanosheet and a channel region of the second nanosheet;
a top source or drain region in direct contact with the first nanosheet; and
a bottom source or drain region in direct contact with the second nanosheet;
wherein a first portion of the top source or drain region is shorted to a first portion of the bottom source or drain region via direct epitaxy contact between the first portion of the top source or drain region and a surface of the first portion of the bottom source or drain region to define a common source or drain region; and
wherein a second portion of the top source or drain region is electrically coupled to a second portion of the bottom source or drain region in series through the first nanosheet, the common source or drain region, and the second nanosheet.
12 . The semiconductor device of claim 11 , further comprising:
a first nanosheet stack comprising the first nanosheet and one or more additional first nanosheets; and
a second nanosheet stack comprising the second nanosheet and one or more additional second nanosheets.
13 . The semiconductor device of claim 12 , wherein the semiconductor device comprises a stacked field effect transistor.
14 . The semiconductor device of claim 13 , wherein the stacked field effect transistor comprises a complementary stacked field effect transistor comprising an nFET and a pFET.
15 . The semiconductor device of claim 14 , wherein the first nanosheet stack defines a portion of one of the nFET and the pFET and the second nanosheet stack defines a portion of the other one of the nFET and the pFET.
16 . The semiconductor device of claim 15 , further comprising a middle dielectric isolation structure between the first nanosheet and the second nanosheet, the middle dielectric isolation structure in direct contact with the common source or drain region.
17 . The semiconductor device of claim 16 , wherein the top source or drain region comprises a first doping type and the bottom source or drain region comprises a second doping type opposite the first doping type.
18 . The semiconductor device of claim 16 , wherein a first sidewall of the first nanosheet is coplanar to a first sidewall of the second nanosheet, and wherein a second sidewall of the first nanosheet is recessed with respect to a second sidewall of the second nanosheet.
19 . The semiconductor device of claim 11 , further comprising a bottom source or drain contact on a surface of the bottom source or drain region.
20 . The semiconductor device of claim 19 , further comprising an isolation structure between the bottom source or drain contact and the top source or drain region, wherein a portion of the isolation structure is between the bottom source or drain contact and the common gate.