KR20070035733A - Molecular Device and Manufacturing Method Thereof - Google Patents

Abstract

A molecular device and a method of manufacturing the same are provided. The device includes a gate electrode and an upper electrode and a lower electrode which are insulated from the gate electrode and formed on and under the gate electrode, respectively, and have a nano gap between the upper electrode and the lower electrode, and the upper electrode and the lower electrode. A metal bridge is formed at each end of the electrode, and a molecular channel layer connecting the metal bridge is formed at the nanogap.

The metal bridge may be formed by connecting the upper electrode and the lower electrode with nanoparticles by applying a predetermined voltage to the two electrodes by contacting a resultant product in which the upper electrode and the lower electrode are formed with gold or metal nanoparticles. The molecular channel layer may be formed by dropping a solution containing a molecule having a reactor that self-bonds with a metal in a nanogap.

Molecular devices, nanoparticles, magnetic coupling, nanogap

Description

Molecular device and its manufacturing method {MOLECULAR DEVICE AND METHOD OF FABRICATING THE SAME}

1 shows a molecular device according to the prior art.

2A and 2B show molecular elements according to a preferred embodiment of the present invention.

3A to 3H illustrate a method of manufacturing a molecular device according to a preferred embodiment of the present invention.

The present invention relates to a molecular device using a compound molecule and a method of manufacturing the same, and more particularly to a molecular device using a nano gap and a method of manufacturing the same.

BACKGROUND OF THE INVENTION In the manufacturing technology of a semiconductor device that forms a pattern on a semiconductor substrate using a photolithography process, the size of the pattern reaches several nanoscales due to the high integration of the device, and thus the limitation of the improvement in the degree of integration is encountered. Recently, molecular devices using self-assembly of molecules have been developed.

A molecular device is a device in which a channel composed of organic molecules having semiconductor characteristics is formed between a source and a drain, and the flow of electrons in the channel region is controlled by a voltage applied to the gate electrode. In order to have it, a technique for forming a nanoscale channel layer is required.

FIG. 1 is a diagram illustrating a monolayer field effect transistor having a self-assembled monolayer (SAM) as a channel layer.

Referring to FIG. 1, a conventional monolayer field effect transistor includes a source electrode 202, a drain electrode 209, a channel layer 208 formed of a self-assembled monolayer, a gate insulating layer 206, and a gate electrode 204. Is done. The source electrode 202 is formed in a predetermined pattern on the semiconductor substrate 201, and an additional source electrode 207 may be formed between the channel layer 208 and the source electrode 202. The gate electrode 204 has a structure in which only a portion of the active region 205 of the source electrode 202 is opened, and the source electrode 202 and the gate electrode 204 are insulated by the interlayer insulating layer 203.

The above-described conventional molecular element is required to form a gate electrode having a wider width than the source electrode 202 and the drain electrode 209, and the length of the channel layer 208 between the source electrode 202 and the drain electrode 209. The thickness dependency of the gate electrode 204, the gate insulating film 206, and the interlayer insulating film 203 is obtained. Therefore, a complex manufacturing process such as patterning the source electrode 202, the gate electrode 204, and the drain electrode 209 by depositing a plurality of thin films is required, and the unit device has a large size. In addition, the limitation of the thickness reduction of the channel layer 208 limits the transfer of charge through the molecular channel.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a molecular device having a structure in which an organic molecule having semiconductor characteristics is used as a channel layer and a channel length can be minimized.

Another object of the present invention is to provide a molecular device having a simple structure and a small occupying area of a unit device and a method of manufacturing the same.

In order to achieve the above technical problem, the present invention provides a molecular device having a metal bridge having a nanogap and a molecular channel layer connecting the nanogap. The device includes a gate electrode and an upper electrode and a lower electrode which are insulated from the gate electrode and formed above and below the gate electrode, respectively. A metal bridge having a nanogap between the upper electrode and the lower electrode and connected at each end to the upper electrode and the lower electrode is formed, and a molecular channel layer connecting the metal bridge is formed at the nanogap. A gate insulating film is interposed between the metal bridge and the molecular channel and the gate electrode to prevent a short circuit between the metal bridge and the gate electrode.

The manufacturing method of the device includes forming a lower electrode on a semiconductor substrate, and forming a gate electrode insulated from the lower electrode and an upper electrode insulated from the gate electrode on the lower electrode. A gate insulating film is formed on sidewalls of the gate electrode, and metal bridges having respective ends connected to the upper electrode and the lower electrode are formed on the gate insulating film. The metal bridge is formed to have a nano gap between the upper electrode and the lower electrode. A molecular channel layer is formed in the nanogap to connect the metal bridges. A metal bridge connected to the lower electrode and the upper electrode may be a source and a drain of a transistor, respectively, and the molecular channel layer is formed in the nanogap of the metal bridge to form a nanoscale transistor channel.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed subject matter is thorough and complete, and that the spirit of the present invention to those skilled in the art will fully convey. In the drawings, the thicknesses of layers and regions are exaggerated for clarity. In addition, where a layer is said to be "on" another layer or substrate, it may be formed directly on the other layer or substrate, or a third layer may be interposed therebetween. Portions denoted by like reference numerals denote like elements throughout the specification.

FIG. 2A is a plan view of a molecular device according to an embodiment of the present invention, and FIG. 2B is a cross-sectional view taken along the line II ′ of FIG. 2A.

2A and 2B, the molecular device according to the present invention includes a lower electrode 10 and an upper electrode 18 formed on the lower electrode 10. The lower electrode 10 may extend in one direction, and the upper electrode 18 may extend in a direction different from the lower electrode 10 to cross the lower electrode 18.

A gate electrode 14 is interposed between the lower electrode 10 and the upper electrode 18. First and second insulating layers 12 and 14 are formed on the lower and upper portions of the gate electrode 14, and gate insulating layers 22 are formed on sidewalls of the gate electrode 14. The gate electrode 14 may extend in parallel with the upper electrode 18. However, the gate electrode 14 may extend in parallel with the lower electrode 18.

Metal bridges 24 connecting the lower electrode 10 and the upper electrode 18 are connected to the lower electrode 10 and the upper electrode 18, and end portions thereof are formed on the gate insulating layer 22. . The metal bridge 24 is connected to opposite surfaces of the lower electrode 10 and the upper electrode 18, and a portion connected to the lower electrode 10 and a portion connected to the upper electrode 18 are separated from each other. Nano gaps (G).

A molecular channel layer 26 is formed in the nanogap G. The molecular channel layer 26 may be formed of a self-assembled monolayer as a molecule having semiconductor characteristics. The molecular channel layer 26 is an organic molecule having a structure that is easily delocalized by being connected by a π-conjugated bond, and easily forms a monomolecular film by reacting with a gold electrode or a metal electrode at an end thereof. It can be formed of a π-conjugated compound having a thiol group or a precursor of a thiol group and a reactive group similar thereto.

The metal bridge 24 is formed by electrostatic trapping of the metal nanoparticles in the gap between the lower electrode 10 and the upper electrode 18, and the metal by Joule heating (Joul Heating) The nano gap G may be formed by breaking the bridge 24. The metal bridge 24 may be formed using nanoparticles of gold or other metals and conductors.

In the present invention, the molecular element may be manufactured as a unit element, and the lower electrode 10 and the upper electrode 18 may be configured in a plurality of parallel line shapes, respectively, to unit each point where the lower electrode and the upper electrode cross each other. It is also possible to form an array structure in which molecular elements are combined.

3A to 3H are diagrams for describing a method of forming a molecular device according to an embodiment of the present invention.

Referring to FIG. 3A, the lower electrode 10 is formed. The lower electrode 10 may be formed on a predetermined substrate, and when forming an array of molecular elements, the lower electrode 10 may be formed in a plurality of parallel line shapes.

Referring to FIG. 3B, the first insulating layer 12, the gate electrode 14, the second insulating layer 16, and the upper electrode 18 are formed on the lower electrode 10. When the array is configured, the first insulating layer 12, the gate electrode 14, the second insulating layer 16, and the upper electrode 18 are sequentially stacked to cross the upper portion of the lower electrode 10. It can form, and it can form a plurality in line shape.

Referring to FIG. 3C, the sidewalls of the gate electrode 14 are oxidized to form the sidewall oxide layer 20. The gate electrode 14 is formed of a material capable of forming an oxide film by oxidation, and the lower electrode 10 and the upper electrode 18 may be formed of a metal having a lower oxidation rate than that of the gate electrode 14. Can be. The sidewall oxide layer 20 may be combined with an element constituting the gate electrode 14 to reduce the width of the gate electrode 14.

Referring to FIG. 3D, the sidewall oxide layer 20 is removed to expose the sidewall of the gate electrode 14. At this time, the first insulating film 12 and the portion of the first insulating film 12 and the second insulating film 16 together with the sidewall oxide film 20, that is, the portion not being in contact with the gate electrode 14, and The second insulating film 16 is also removed. The first insulating layer 12 and the second insulating layer 16 are removed to expose a portion of the lower electrode 10 and the upper electrode 18. Opposing surfaces of the lower electrode 10 and the upper electrode 18 are exposed.

Referring to FIG. 3E, a gate insulating layer 22 is formed on sidewalls of the exposed gate electrode 14. The gate insulating layer 22 may be formed by oxidizing sidewalls of the gate electrode 14. In this case, the exposed surfaces of the lower electrode 10 and the upper electrode 18 may also be oxidized, but may be removed by cleaning after the gate insulating layer 22 is formed.

Referring to FIG. 3F, the resultant in which the gate insulating layer 22 is formed is brought into contact with a solution containing the metal nanoparticles 24 ′, and a predetermined voltage (V) is applied to the lower electrode 10 and the upper electrode 18. When V1 and V2 are applied, nanoparticles are electrostatically trapped on the lower electrode 10 and the upper electrode 18, and the captured metal nanoparticles are connected to form a metal bridge 24. In this case, a DC power source or an AC power source may be connected to the lower electrode 10 and the upper electrode 18. For example, a solution containing Au nonoparticles is dropped onto a substrate, and a metal bridge 24 is formed by applying an AC power of 1 MHz between the lower electrode 10 and the upper electrode 18. can do.

Alternatively, the metal bridge 24 may be formed by adsorbing the metal element to the lower electrode 10 and the upper electrode 18 through electrolysis of an aqueous solution containing the metal element.

Referring to FIG. 3G, the resultant in which the metal bridge 24 is formed is washed, and predetermined voltages V3 and V4 are applied to the lower electrode 10 and the upper electrode 18, and the metal bridge is heated by Joule heat. Hang up (24). Since the metal bridge 24 may have a nanoscale cross section, it may be broken even when a relatively low voltage is applied between the lower electrode 10 and the upper electrode 18. At the same time as the metal bridge 24 is cut off, the flow of current flowing through the metal bridge 24 is stopped, and a nano gap G is formed in the metal bridge 24.

Referring to FIG. 3F, a molecular channel layer 26 connecting the nanogap G by contacting the resultant product having the nanogap G with a solution containing the organic molecules 26 ′ _ having semiconductor characteristics is formed. In this case, the organic molecules are self-assembled monolayers, and may be organic molecules having a structure that is connected by a π-conjugated bond to facilitate electron delocalization. A predetermined voltage is applied between the electrode 10 and the upper electrode 18 to connect the nanogap G through an electrostatic trap, or the terminal easily reacts with a gold electrode or a metal electrode to easily form a monomolecular film. In the case of a π-conjugated compound having a thiol group or a precursor of a thiol group and similar reactive groups, the nano-gap G may be connected to the metal bridge 24 by a self-assembly.If no reactive group is a single compound when coating thiol group, a thiol group or the like reactive precursor to the metal bridge 24 it may be an organic molecule having a semiconductor characteristic that connect the nano-gap (G).

As described above, the present invention forms a metal bridge having a nanogap smaller than the gap that can be formed by a photolithography process or deposition, and forming a molecular channel having semiconductor characteristics in the nanogap, so that the length of the channel Molecular devices having a structure that can be minimized can be manufactured.

The molecular element according to the present invention has a small occupied area because the unit element can be formed between two electrodes crossing each other and a third electrode parallel to either one of the two electrodes to cross the two electrodes. Molecular devices can be formed, and further, an array of unit devices can be easily constructed.

Claims (11)

A gate electrode; An upper electrode and a lower electrode insulated from the gate electrode and formed on upper and lower portions of the gate electrode, respectively; A metal bridge having a nano gap between the upper electrode and the lower electrode and having respective ends connected to the upper electrode and the lower electrode; A molecular channel layer formed in the nanogap to connect the metal bridges; And And a gate insulating layer interposed between the metal bridge and the molecular channel and the gate electrode. The method according to claim 1, The upper electrode and the lower electrode has a line shape, respectively, characterized in that extending in different directions. The method according to claim 2, And the gate electrode extends in parallel with the upper electrode or the lower electrode. The method according to claim 2, And the metal bridge is formed at the intersection of the upper electrode and the lower electrode. The method according to claim 1, The molecular channel layer is a self-assembled monolayer, The metal bridge is a molecular device, characterized in that the gold (Au) coated with a thiol at the end forming the nano-gap. Forming a lower electrode extending in one direction on the semiconductor substrate; Forming an insulating film interposed between the gate electrode and the upper electrode, the gate electrode and the lower electrode, and the gate electrode and the upper electrode; Forming a gate insulating film on sidewalls of the gate electrode; Forming a metal bridge on the gate insulating layer, the metal bridge having a nano gap between the upper electrode and the lower electrode and having respective ends connected to the upper electrode and the lower electrode; And Forming a molecular channel layer in the nanogap to connect the metal bridges. The method according to claim 6, Forming the gate electrode and the upper electrode, Sequentially stacking a first insulating film, a gate conductive film, a second insulating film, and an upper conductive film on the entire surface of the substrate on which the lower electrode is formed; And And patterning the upper conductive film, the second insulating film, the gate conductive film, and the first insulating film. The method according to claim 6, Before forming the gate insulating film, Oxidizing a sidewall of the gate electrode to form a sidewall oxide film; And Removing the edges of the first and second insulating layer patterns and the sidewall oxide layer to expose sidewalls of the gate electrode and portions of opposite surfaces of the upper electrode and the lower electrode, And said metal bridge is connected to exposed opposing surfaces of said upper electrode and said lower electrode. The method according to claim 6, Forming the metal bridge, Dipping the intersection of the lower electrode and the upper electrode in a solution containing a metal nanocrystal; Applying a voltage to the upper electrode and the lower electrode to form a nanobridge connecting the upper electrode and the lower electrode; And Separating the intersection of the lower electrode and the upper electrode from a solution containing a metal nanocrystal; And applying a voltage between the upper electrode and the lower electrode to form a nano gap in which the nano bridge is disconnected. The method according to claim 6, Forming the metal bridge, Dipping the intersection of the lower electrode and the upper electrode in an electrolyte containing metal ions; Forming a nanobridge connecting the upper electrode and the lower electrode by applying a voltage to the upper electrode and the lower electrode; And Separating an intersection of the lower electrode and the upper electrode from the electrolyte solution; And applying a voltage between the upper electrode and the lower electrode to form a nano gap in which the nano bridge is disconnected. The method according to claim 6, The molecular channel layer is a method of manufacturing a molecular device, characterized in that to form a solution containing a molecule having a metal affinity group at the end by contacting the nanogap to connect the nanogap.

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