Semiconductor device with floating main body region vertically separting source from drain and method of forming the same
A semiconductor device includes: a substrate; a source region disposed on the substrate; a drain region disposed on the source region; and a floating main body region disposed between the source region and the drain region. The floating main body region vertically separates the source region from the drain region. The semiconductor device further includes: a gate region laterally wrapped around the floating main body region; and a gate dielectric located between the floating main body region and the gate region, and insulated the floating main body region from the gate region. A material of the gate dielectric has a negative capacitance feature.
1 . A semiconductor device, comprising:
a substrate;
a source region disposed on the substrate;
a drain region disposed on the source region;
a floating main body region disposed between the source region and the drain region, wherein the floating main body region vertically separates the source region from the drain region;
a gate region laterally wrapped around the floating main body region, wherein the gate region wraps around a portion of the source region and a portion of the drain region; and
a gate dielectric located between the floating main body region and the gate region, and insulated the floating main body region from the gate region, wherein a material of the gate dielectric has a negative capacitance (NC) feature,
wherein the gate dielectric comprises an air gap in contact with the drain region, wherein, from the perspective of the floating main body region, a portion of the gate dielectric close to the source region and a portion of the gate dielectric close to the drain region appear to be an asymmetrical configuration.
2 . The semiconductor device of claim 1 , further comprising a source line disposed on the substrate, wherein the source line is electrically connected to the source region.
3 . The semiconductor device of claim 2 , further comprising a word line extended outward from the gate region, wherein an extending direction of the word line is perpendicular to an extending direction of the source line.
4 . The semiconductor device of claim 2 , further comprising an inter-layer dielectric (ILD) covering the source line.
5 . The semiconductor device of claim 4 , wherein a top surface of the inter-layer dielectric is lower than an interface between the source region and the floating main body region.
6 . The semiconductor device of claim 1 , further comprising an inter-layer dielectric covering the gate region.
7 . The semiconductor device of claim 6 , further comprising a bit line disposed on the inter-layer dielectric, wherein the bit line is electrically connected to the drain region.
8 . The semiconductor device of claim 7 , further comprising an inter-metal dielectric (IMD) disposed on the bit line.
9 . The semiconductor device of claim 1 , further comprising an interfacial layer located between the floating main body region and the gate dielectric, and separates the floating main body region from the gate dielectric.
10 . A method of forming a semiconductor device, comprising:
providing a substrate;
sequentially forming a source region, a floating main body region, and a drain region on the substrate by sequentially depositing a source layer, a floating main body layer, and a drain layer on the substrate, followed by patterning the drain layer, the floating main body layer, and a portion of the source layer, wherein a portion of the source layer not patterned becomes a source line electrically connected to the source region;
forming a gate region wrapping around the floating main body region, wherein the gate region wraps around a portion of the source region and a portion of the drain region; and
forming a gate dielectric wrapping around the floating main body region before forming the gate region, wherein a material of the gate dielectric has a negative capacitance feature,
wherein the gate dielectric layer and the gate layer are conformally deposited on an exposed surface of the source line, on sidewalls of the source region and the floating main body region, and on a sidewall and a top surface of the drain region, followed by etching back the gate dielectric layer and the gate layer.
11 . The method of claim 10 , further comprising forming an inter-layer dielectric covering the source region, the floating main body region, and the drain region before conformally depositing the gate dielectric layer and the gate layer, followed by etching the inter-layer dielectric to expose the drain region, the floating main body region, and a portion of the source region.
12 . The method of claim 10 , further comprising conformally depositing an interfacial material layer on the exposed surface of the source line, on the sidewalls of the source region and the floating main body region, and on the sidewall and the top surface of the drain region before conformally depositing the gate dielectric layer and the gate layer.
13 . The method of claim 12 , further comprising etching back the interfacial material layer to become an interfacial layer, wherein a material feature of the interfacial layer is different from a material feature of the gate dielectric.
14 . The method of claim 10 , wherein etching back the gate dielectric layer and the gate layer further comprising etching a top surface of the gate dielectric layer below a top surface of the gate layer to form a recess between the floating main body region and the gate region.
15 . The method of claim 14 , further comprising forming an inter-layer dielectric covering the gate dielectric and the gate region, wherein the inter-layer dielectric seals the recess to become an air gap.