Laterally grown nanotubes and method of formation
View Patent ↗A semiconductor device has lateral conductors or traces that are formed of nanotubes such as carbon. A sacrificial layer is formed overlying the substrate. A dielectric layer is formed overlying the sacrificial layer. A lateral opening is formed by removing a portion of the dielectric layer and the sacrificial layer which is located between two columns of metallic catalysts. The lateral opening includes a neck portion and a cavity portion which is used as a constrained space to grow a nanotube. A plasma is used to apply electric charge that forms an electric field which controls the direction of formation of the nanotubes. Nanotubes from each column of metallic catalyst are laterally grown and either abut or merge into one nanotube. Contact to the nanotube may be made from either the neck portion or the columns of metallic catalysts.
1. A method of laterally growing nanotubes comprising:
forming a lateral opening which extends between two metallic catalysts, the lateral opening comprising a neck portion and a cavity portion; and
using the cavity portion of the lateral opening as a constrained space to grow a nanotube to form a continuous lateral electrical conductor between the two metallic catalysts; and
forming a plasma over the neck portion of the lateral opening to limit growth of the nanotube exclusively to substantially within a straight path between the two metallic catalysts.
2. The method of claim 1 further comprising:
depositing electrical charges from the plasma along the neck portion of the lateral opening and on a lower surface of the cavity portion under the neck portion to induce a radial electric field within the cavity portion of the lateral opening that controls growth direction of the nanotube.
3. The method of claim 1 wherein forming the lateral opening further comprises:
providing a substrate;
forming a sacrificial layer overlying the substrate;
forming an insulating layer overlying the sacrificial layer; and
etching the insulating layer and the sacrificial layer to form the lateral opening by removing the sacrificial layer between the two metallic catalysts.
4. The method of claim 1 further comprising:
providing a substrate;
forming a sacrificial layer overlying the substrate;
forming an insulating layer overlying the sacrificial layer;
etching the insulating layer and the sacrificial layer to form a first opening and a second opening which define a location for the two metallic catalysts;
forming a metallic catalyst material layer within a portion of each of the first opening and the second opening, a portion of the metallic catalyst material layer being exposed to the lateral opening; and
exposing the portion of the metallic catalyst material layer exposed to the lateral opening to a carbon-containing material for stimulating growth of carbon nanotubes within the lateral opening.
5. The method of claim 1 further comprising:
forming the neck portion of the lateral opening substantially in a center of the lateral opening.
6. A method of laterally growing nanotubes, comprising:
forming a lateral opening which extends between two metallic catalysts, the lateral opening comprising a neck portion and a cavity portion; and
using the cavity portion of the lateral opening as a constrained space to grow a nanotube to form a continuous lateral electrical conductor between the two metallic catalysts; and
filling the neck portion with a conductive material to form a via for electrical contact to the continuous lateral electrical conductor.
7. A method of laterally growing nanotubes comprising:
forming a substrate;
forming a sacrificial layer overlying the substrate;
forming a dielectric layer overlying the sacrificial layer;
forming a lateral opening by removing a portion of the dielectric layer and all of the sacrificial layer located between two columns of metallic catalysts, the lateral opening comprising a neck portion formed from the dielectric layer that is removed and a cavity portion formed from the sacrificial layer that is removed;
using the cavity portion of the lateral opening as a constrained space to grow a nanotube in a radial direction from each of the two columns of metallic catalysts to form a continuous lateral electrical conductor between the two columns of metallic catalysts; and
forming a plasma over the neck portion of the lateral opening to limit growth of the nanotube exclusively to substantially within a straight path between the two metallic catalysts, the plasma depositing electrical charges along the neck portion of the lateral opening and on a lower surface of the cavity portion under the neck portion to induce a radial electric field within the cavity portion of the lateral opening that controls growth direction of the nanotube.
8. A method of laterally growing nanotubes, comprising:
forming a substrate;
forming a sacrificial layer overlying the substrate;
forming a dielectric layer overlying the sacrificial layer;
forming a lateral opening by removing a portion of the dielectric layer and all of the sacrificial layer located between two columns of metallic catalysts, the lateral opening comprising a neck portion formed from the dielectric layer that is removed and a cavity portion formed from the sacrificial layer that is removed;
using the cavity portion of the lateral opening as a constrained space to grow a nanotube in a radial direction from each of the two columns of metallic catalysts to form a continuous lateral electrical conductor between the two columns of metallic catalysts; and
filling the neck portion with a conductive material to form a via for electrical contact to the continuous lateral electrical conductor.
9. The method of claim 7 further comprising:
forming the neck portion of the lateral opening substantially in a center of the lateral opening.
10. The method of claim 7 further comprising:
forming a carbon nanotube as the nanotube, the two columns of metallic catalysts comprising one of iron, cobalt, platinum, nickel or molybdenum.