Semiconductor structure with increased channel length and method for forming the same
A method for forming a semiconductor structure includes the following operations. A substrate is formed. The substrate includes a body part and a protrusion part located on a surface of the body part. A gate electrode located on the body part and distributed around sidewalls of the protrusion part is formed. A first doped region and a second doped region located in the body part and distributed at two opposite sides of the gate electrode are formed.
1 . A method for forming a semiconductor structure, comprising:
forming a substrate, wherein the substrate comprises a body part and a protrusion part located on a surface of the body part;
forming a gate electrode located on the body part and distributed around sidewalls of the protrusion part; and
forming a first doped region and a second doped region located in the body part and distributed at two opposite sides of the gate electrode;
before forming the first doped region and the second doped region located in the body part and distributed at the two opposite sides of the gate electrode,
forming a first dielectric layer covering the gate electrode; and
implanting a first doping ion into the body part at two opposite sides of the protrusion part to form second lightly doped regions;
after forming the first doped region and the second doped region located in the body part and distributed at the two opposite sides of the gate electrode,
forming a second dielectric layer covering the surface of the body part, a surface of the first dielectric layer, and a surface of the insulating layer;
etching the second dielectric layer, the first dielectric layer and the insulating layer to form a first through hole exposing the first lightly doped region in the protrusion part, a second through hole exposing the first doped region in the body part, a third through hole exposing the second doped region in the body part, and fourth through holes exposing the gate electrode; and
forming a first plug electrically connected to the first lightly doped region, a second plug electrically connected to the first doped region, a third plug electrically connected to the second doped region, and fourth plugs electrically connected to the gate electrode by filling a conductive material into the first through hole, the second through hole, the third through hole and the fourth through holes.
2 . The method for forming a semiconductor structure of claim 1 , wherein
the forming a substrate comprises:
providing an initial substrate, wherein the initial substrate comprises a first lightly doped region;
forming an initial insulating layer covering a surface of the initial substrate; and
forming the substrate comprising the body part and the protrusion part located on the surface of the body part, and an insulating layer on a surface of the protrusion part, by etching the initial insulating layer and the initial substrate, wherein the protrusion part comprises the first lightly doped region, and the body part does not comprise the first lightly doped region.
3 . The method for forming a semiconductor structure of claim 2 , wherein
the forming a gate electrode located on the body part and distributed around sidewalls of the protrusion part comprises:
forming a gate dielectric layer covering a sidewall of the protrusion part and part of the surface of the body part; and
forming the gate electrode located on a surface of the gate dielectric layer and distributed around the sidewalls of the protrusion part.
4 . The method for forming a semiconductor structure of claim 3 , wherein
the forming the gate electrode located on a surface of the gate dielectric layer and distributed around the sidewalls of the protrusion part comprises:
depositing a gate material layer on the surface of the gate dielectric layer and a surface of the insulating layer; and
removing all the gate material layer on the surface of the insulating layer and part of the gate material layer above the body part, such that the gate material layer remaining on the surface of the gate dielectric layer and distributed around the sidewall s of the protrusion part forms the gate electrode.
5 . The method for forming a semiconductor structure of claim 1 , wherein
the forming a first doped region and a second doped region located in the body part and distributed at two opposite sides of the gate electrode comprises:
implanting a second doping ion into the body part at the two opposite sides of the protrusion part to form the first doped region and the second doped region respectively in the body part at the two opposite sides of the gate electrode;
wherein projections of the second light doped regions partially overlap with a projection of the first doped region and a projection of the second doped region respectively in a direction perpendicular to the surface of the body part.
6 . The method for forming a semiconductor structure of claim 1 , wherein
the forming a first plug electrically connected to the first lightly doped region, a second plug electrically connected to the first doped region, a third plug electrically connected to the second doped region, and fourth plugs electrically connected to the gate electrode comprises:
forming a first contact layer at a bottom of the first through hole, forming a second contact layer at a bottom of the second through hole, forming a third contact layer at a bottom of the third through hole and forming fourth contact layers at bottoms of the fourth through holes;
forming a first diffusion barrier layer on a surface of the first contact layer and an inner wall of the first through hole, forming a second diffusion barrier layer on a surface of the second contact layer and an inner wall of the second through hole, forming a third diffusion barrier layer on a surface of the third contact layer and an inner wall of the third through hole, and forming fourth diffusion barrier layers on surfaces of the fourth contact layers and inner walls of the fourth through holes; and
forming the first plug on the first diffusion barrier layer, the second plug on the second diffusion barrier layer, the third plug on the third diffusion barrier layer, and the fourth plugs on the fourth diffusion barrier layers by filling the conductive material into the first through hole, the second through hole, the third through hole and the fourth through holes.
7 . The method for forming a semiconductor structure of claim 1 , wherein
a plurality of the fourth plugs are distributed around a periphery of a same gate electrode and are all electrically connected to the same gate electrode.
8 . The method for forming a semiconductor structure of claim 1 , wherein
a height of the gate electrode is smaller than a height of the protrusion part in a direction perpendicular to the surface of the body part.
9 . A semiconductor structure, comprising: a substrate comprising a body part and a protrusion part located on a surface of the body part; a gate electrode located on the body part and distributed around sidewalls of the protrusion part; a first doped region located in the body part; and a second doped region located in the body part, wherein the first doped region and the second doped region are distributed at two opposite sides of the gate electrode; a first lightly doped region located in the protrusion part and second lightly doped regions located in the body part at two opposite sides of the protrusion part, wherein projections of the second light doped regions partially overlap with a projection of the first doped region and a projection of the second doped region respectively in a direction perpendicular to the surface of the body part; a first plug extending in the direction perpendicular to the surface of the body part and electrically connected to the first lightly doped region; a second plug extending in the direction perpendicular to the surface of the body part and electrically connected to the first doped region; a third plug extending in the direction perpendicular to the surface of the body part and electrically connected to the second doped region; and fourth plugs extending in the direction perpendicular to the surface of the body part and electrically connected to the gate electrode.
10 . The semiconductor structure of claim 9 , wherein
a plurality of the fourth plugs are distributed around a periphery of a same gate electrode and are all electrically connected to the same gate electrode.
11 . The semiconductor structure of claim 9 , further comprising:
a first contact layer located between the first lightly doped region and the first plug;
a second contact layer located between the first doped region and the second plug;
a third contact layer located between the second doped region and the third plug; and
fourth contact layers located between the gate electrode and the fourth plugs.
12 . The semiconductor structure of claim 9 , further comprising:
an insulating layer covering a top surface of the protrusion part, wherein the first plug penetrates through the insulating layer in the direction perpendicular to the surface of the body part.
13 . The semiconductor structure of claim 12 , further comprising:
a first dielectric layer covering a surface of the gate electrode; and
a second dielectric layer covering the surface of the body part, a surface of the first dielectric layer and a surface of the insulating layer,
wherein both the second plug and the third plug penetrate through the second dielectric layer in the direction perpendicular to the surface of the body part, and the fourth plugs penetrate through the first dielectric layer in the direction perpendicular to the surface of the body part.
14 . The semiconductor structure of claim 9 , wherein
a height of the protrusion part in a direction perpendicular to the surface of the body part is greater than a width of the protrusion part in a direction parallel to the surface of the body part.
15 . The semiconductor structure of claim 9 , wherein
a height of the gate electrode is smaller than a height of the protrusion part in a direction perpendicular to the surface of the body part.