Forming 3D transistors using 2D van der WAALS materials
View Patent ↗A method includes etching a dielectric layer to form a dielectric fin, depositing a transition metal dichalcogenide layer on the dielectric fin, and performing an anisotropic etching process on the transition metal dichalcogenide layer. Horizontal portions of the transition metal dichalcogenide layer are removed, and vertical portions of the transition metal dichalcogenide layer on sidewalls of the dielectric fin remain to form a vertical semiconductor ring. The method further includes forming a gate stack on a first portion of the two-dimensional semiconductor vertical semiconductor ring, and forming a source/drain contact plug, wherein the source/drain contact plug contacts sidewalls of a second portion of the vertical semiconductor ring.
1 . A method comprising:
etching a dielectric layer to form a dielectric fin;
depositing a transition metal dichalcogenide layer on the dielectric fin;
performing a first anisotropic etching process on the transition metal dichalcogenide layer, wherein horizontal portions of the transition metal dichalcogenide layer are removed, and vertical portions of the transition metal dichalcogenide layer on sidewalls of the dielectric fin remain to form a vertical semiconductor ring;
forming a gate stack on a first portion of the vertical semiconductor ring; and
forming a source/drain contact plug, wherein the source/drain contact plug contacts sidewalls of the vertical semiconductor ring.
2 . The method of claim 1 , wherein the depositing the transition metal dichalcogenide layer comprises depositing a MoS 2 layer.
3 . The method of claim 1 , wherein the depositing the transition metal dichalcogenide layer is performed using chemical vapor deposition with MoO 3 powder and sulfur powder as precursors.
4 . The method of claim 1 further comprising, after the forming the gate stack, depositing a contact etch stop layer and an inter-layer dielectric covering the vertical semiconductor ring.
5 . The method of claim 4 , wherein forming the source/drain contact plug comprises:
performing a second anisotropic etching process to form a contact opening penetrating through the inter-layer dielectric, with the contact etch stop layer exposed to the contact opening;
performing an isotropic etching process on the contact etch stop layer to reveal the transition metal dichalcogenide layer to the contact opening; and
filling the contact opening with a conductive material.
6 . The method of claim 1 further comprising forming a gate spacer on a sidewall of the gate stack, and the source/drain contact plug contacts a sidewall of the gate spacer.
7 . The method of claim 1 , wherein the etching the dielectric layer to form the dielectric fin is performed using an additional dielectric layer as an etch stop layer, and the source/drain contact plug forms an interface with the vertical semiconductor ring, and wherein the interface extends from a top end of the vertical semiconductor ring to a top surface of the additional dielectric layer.
8 . A method of manufacturing a semiconductor device, the method comprising:
forming a dielectric fin;
forming a 2D material layer on sidewalls of the dielectric fin, wherein a top surface of the dielectric fin is exposed after forming the 2D material layer;
forming a gate stack on the dielectric fin and the 2D material layer, wherein the gate stack contacts a first portion of a sidewall of the 2D material layer, and wherein the gate stack contacts the top surface of the dielectric fin; and
forming a source/drain contact plug contacting a second portion of the sidewall of the 2D material layer, wherein the source/drain contact plug is free of the 2D material.
9 . The method of claim 8 , wherein the 2D material layer has a shape of a ring in a top-down view.
10 . The method of claim 8 , wherein the 2D material layer comprises a transition metal dichalcogenide.
11 . The method of claim 10 , wherein the transition metal dichalcogenide is MoS 2 or MoSe 2 .
12 . The method of claim 10 , wherein the transition metal dichalcogenide is WS 2 or WSe 2 .
13 . The method of claim 8 , wherein the 2D material comprises a plurality of monolayers.
14 . The method of claim 8 , wherein the dielectric fin has a height between 20 nm and 60 nm.
15 . A method of manufacturing a semiconductor device, the method comprising:
forming a dielectric fin on a dielectric layer;
forming a semiconductor ring on sidewalls of the dielectric fin, the semiconductor ring comprising a transition metal dichalcogenide material;
forming a gate stack on a top surface of the dielectric fin and a first portion of a top surface of the semiconductor ring; and
forming a source/drain contact plug on a second portion of the top surface of the semiconductor ring, wherein the source/drain contact plug overlaps the top surface of the dielectric fin in a top-down view.
16 . The method of claim 15 , wherein the gate stack contacts a first portion of a sidewall of the semiconductor ring and the source/drain contact plug contacts a second portion of the sidewall of the semiconductor ring.
17 . The method of claim 15 , wherein the transition metal dichalcogenide material is a 2D material comprising a plurality of monolayers bonded together by Van Der Waals force.
18 . The method of claim 15 , wherein the transition metal dichalcogenide material comprises sulfur or selenium.
19 . The method of claim 18 , wherein the transition metal dichalcogenide material comprises molybdenum or tungsten.
20 . The method of claim 15 , wherein the dielectric fin and the dielectric layer comprise different materials.