Semiconductor device and method for forming the same
View Patent ↗A semiconductor device includes a substrate. A 2-D material channel layer is over the substrate, in which the 2-D material channel layer includes a channel region and source/drain regions on opposite sides of the channel region. Source/drain metals are over of the source/drain regions of the 2-D material channel layer. A gate metal is over the substrate and non-overlapping the 2-D material channel layer along a vertical direction, in which the gate metal is laterally separated from the 2-D material channel layer by an air gap.
1 . A method, comprising:
forming a 2-D material layer over a substrate;
forming a gate contact electrode and source/drain contact electrodes over the 2-D material layer;
forming a gate metal extending from a top surface of the gate contact electrode to a sidewall of the gate contact electrode;
forming a first patterned mask covering a channel region of the 2-D material layer, wherein the first patterned mask non-overlaps the gate contact electrode along a vertical direction;
etching portions of the 2-D material layer uncovered by the first patterned mask, such that the channel region of the 2-D material layer is laterally separated from the gate contact electrode and the gate metal, wherein a lateral distance between the gate metal and the channel region of the 2-D material layer is less than a lateral distance between the gate contact electrode and the channel region of the 2-D material layer; and
removing the first patterned mask.
2 . The method of claim 1 , further comprising forming a 2-D material passivation layer over the 2-D material layer prior to forming the gate contact electrode and the source/drain contact electrodes.
3 . The method of claim 1 , wherein the first patterned mask non-overlaps the gate metal along the vertical direction.
4 . The method of claim 1 , wherein the 2-D material layer comprises a remaining portion under the gate contact electrode after etching the portions of the 2-D material layer, wherein the remaining portion of the 2-D material layer is laterally separated from the channel region of the 2-D material layer.
5 . The method of claim 1 , wherein the 2-D material layer comprises graphene.
6 . A method, comprising:
forming a 2-D material layer over a substrate;
forming a gate contact electrode and source/drain contact electrodes over the 2-D material layer;
forming a metal layer over the 2-D material layer, wherein the metal layer comprises source/drain metals and a gate metal, wherein the gate metal extends from a top surface of the gate contact electrode to a sidewall of the gate contact electrode; and
patterning the 2-D material layer to define a channel region of the 2-D material layer between the source/drain metals in a first cross-sectional view, wherein the gate metal does not overlap the channel region of the 2-D material layer in the first cross-sectional view, and wherein in a second cross-sectional view that is perpendicular to the first cross-sectional view, a lateral distance between the gate metal and the channel region of the 2-D material layer is less than a lateral distance between the gate contact electrode and the channel region of the 2-D material layer.
7 . The method of claim 6 , further comprising depositing a passivation layer over the 2-D material layer prior to forming the metal layer.
8 . The method of claim 7 , wherein the passivation layer is made of a 2-D material.
9 . The method of claim 7 , wherein the passivation layer and the 2-D material layer are made of different 2-D materials.
10 . The method of claim 6 , wherein patterning the 2-D material layer comprises removing a portion of the 2-D material layer, such that in the second cross-sectional view, the channel region of the 2-D material layer is spaced apart from a remaining portion of the 2-D material layer under the gate metal through an air gap.
11 . The method of claim 10 , wherein in the second cross-sectional view the gate metal is spaced apart from the channel region of the 2-D material layer by a non-zero distance.
12 . The method of claim 10 , wherein the air gap exposes a top surface of the substrate.
13 . The method of claim 6 , wherein the 2-D material layer comprises graphene.
14 . A method, comprising:
forming a 2-D material layer over a substrate;
forming a 2-D material passivation layer over the 2-D material layer
forming an electrode layer over the 2-D material passivation layer, the electrode layer comprising source/drain contact electrodes and a gate contact electrode;
forming a metal layer over the 2-D material layer, wherein the metal layer comprises source/drain metals and a gate metal, wherein the gate metal extends from a top surface of the gate contact electrode to a sidewall of the gate contact electrode; and
patterning the 2-D material layer and the 2-D material passivation layer to define a channel region of the 2-D material layer between the source/drain metals in a first cross-sectional view, in a second cross-sectional view that is perpendicular to the first cross-sectional view, the 2-D material passivation layer having a first portion covering a top surface of the channel region of the 2-D material layer, and a second portion below the gate contact electrode, and the first portion is spaced apart from the second portion, and wherein in the second cross-sectional view, a lateral distance between the gate metal and the channel region of the 2-D material layer is less than a lateral distance between the gate contact electrode and the channel region of the 2-D material layer.
15 . The method of claim 14 , wherein the 2-D material passivation layer and the 2-D material layer are made of different materials.
16 . The method of claim 14 , wherein patterning the 2-D material layer and the 2-D material passivation layer comprises:
forming a mask covering the first portion of the 2-D material passivation layer; and
etching the 2-D material layer and the 2-D material passivation layer to expose a top surface of the substrate.
17 . The method of claim 14 , wherein in the second cross-sectional view the gate contact electrode does not overlap the first portion of the 2-D material passivation layer.
18 . The method of claim 14 , wherein in the second cross-sectional view the gate contact electrode is spaced apart from the channel region of the 2-D material layer by a non-zero distance.
19 . The method of claim 14 , wherein the gate contact electrode is absent in the first cross-sectional view.
20 . The method of claim 14 , wherein the 2-D material passivation layer is made of transition metal dichalcogenide (TMD).