KR20070058937A - Organic semiconductor devices and fabrication methods of the same - Google Patents

Abstract

An organic semiconductor device is provided to vary a distance between nano particles by using a charge storage medium as a nano particle with a uniform size distribution. An organic semiconductor layer includes a first electrode(210), an electron channel layer(230) formed on the first electrode and a second electrode(250) formed on the electron channel layer. The electron channel layer is composed of a lower organic material layer(231) formed on the first electrode, a nano particle layer(233), and an upper organic material layer(235) formed on the nano particle layer. The nano particle layer is formed on the lower organic material layer, nano particles having a predetermined size such that the nano particles are separated from each other by a predetermined interval. The electron channel layer can maintain a high conductive state and a low conductive state when a voltage is not applied from the outside.

Description

Organic semiconductor devices and fabrication methods thereof

FIG. 1A is a side cross-sectional view of an organic semiconductor device according to the prior art, FIG. 1B is an organic material structure constituting the organic semiconductor device of FIG. 1A, and FIG. 1C is a graph of voltage-current characteristics of the organic semiconductor device.

2 illustrates a structure of an organic semiconductor device according to an embodiment of the present invention.

FIG. 3A is a diagram illustrating a general membrane manufacturing step using the langmuir-blodgett method.

FIG. 3B is a detailed structure of an organic semiconductor device in which an LB film manufactured by using FIG. 3A is stacked.

4 is a graph illustrating characteristics of the organic semiconductor device of FIG. 2.

** Description of the main parts of the drawing **

200: organic semiconductor element 210: first electrode

250: second electrode 230: electron channel layer

231: lower organic layer 231a, 235a: monomolecular organic film

233: nanoparticle layer 235: upper organic layer

The present invention relates to an organic semiconductor device and a method for manufacturing the same, and more particularly, to an organic semiconductor device including an electron channel layer having a nanoparticle layer formed of nanoparticles and a method for manufacturing the same.

Globally, semiconductor device technology has reached the stage of realizing gigabit DRAM, and it is predicted that more than 100G bit integrated circuit will be realized in the next few years. As the semiconductor devices become more and more highly integrated, not only the device size is reduced but also characteristics such as ultra-high speed, high capacity, high integration, power consumption reduction, and high functionalization. Furthermore, it can be expected that core components in a ubiquitous communication environment can be provided in a system-on-chip (SoC) form.

In particular, the current nonvolatile memory technology mainly consists of flash memory based on the charge control of the electron, the current flash memory uses the operating voltage of the CMOS. However, because flash memory charges the internal power (1.5 ~ 5V) to make 17 ~ 20V for programming or erasing information, the tunneling oxide breakdown due to high voltage is used. This occurs, and thus the reliability problem of the memory itself is frequently highlighted.

Accordingly, in the future, when the flash memory is reduced to a 65 nm node, the thickness of the flash memory tunneling oxide should also be reduced. In this case, the equivalent oxide thickness (EOT: equivalent) is also used in the design so that the breakdown of the tunneling oxide does not occur. The manufacturing process is very complicated because the oxide thickness must be taken into account. In addition, when scaling down to 65 nm or less, noise is generated between cells, so that there is a limit to reducing device scale, which raises many questions about the feasibility of device operation.

Moreover, in low voltage operation, where current flash memory is required for low power consumption, it is difficult to have sufficient cell current device characteristic margin, which can replace the current flash memory, which can overcome the limitations of these physical and electrical problems. There is an urgent need for the development of new functional memory devices. Recently, researches on organic electronic devices that are expected to satisfy all of the requirements of such nonvolatile electronic devices have been actively conducted.

Infineon Technologies AG reported the structure and device characteristics of highly integrated nonvolatile memory using organic materials in IEDM 2003. However, it is not mentioned in detail. a lower electrode and with a simple 1R type memory device using the above organic material thin film is formed between the electrodes, the memory cell cross-talk patterned or dielectric spacer (dielectric spacer) to reduce the (cross-talk) between, I _{on / off} is 10 ² Data retention time was reported as about 8 months.

UCLA has reported a nonvolatile organic semiconductor device using organic / metal / organic multilayer thin films that exhibit electrical bistability. The device disclosed by UCLA will be described in detail with reference to FIGS. 1A to 1C.

FIG. 1A is a side cross-sectional view of an organic semiconductor device according to the prior art, FIG. 1B is an organic material structure constituting the organic semiconductor device of FIG. 1A, and FIG. 1C is a graph of voltage-current characteristics of the organic semiconductor device.

1A and 1B, the organic semiconductor device 100 includes a multilayer structure of a metal electrode 101 / a first organic material 102 / an intermediate metal layer 103 / a second organic material 104 / a metal electrode 105. Referring to FIG. 1B, the organic materials 102 and 104 constituting the organic semiconductor device 100 use AIDCN (2-amino-4, 5-imidazoledicarbonitrile), and upper and lower metal electrodes 101, 105) and the intermediate metal layer 103 is aluminum (Al). As shown in FIG. 1C, the organic semiconductor device 100 configured as described above has a large Ion / off of about 10 ⁴ to 10 ⁵ and a data retention time of several months.

In addition, L.P. Ma et al., Applied Physics Letters, 82 (9), 1419 (2003), explained that electrical stability is caused by differences in electrical conductivity due to charges stored in the nanostructures of organic and intermediate metal layers. That is, when the intermediate metal layer is deposited in a thin film thickness of 5 to 20 nm and then the intermediate metal layer is agglomerated into nanoparticles by heat generated during the organic material deposition process, it can be predicted that the nanoparticle becomes an object capable of storing charge. . However, as described above, when the metal thin film is deposited and then nanoparticles are formed by heat treatment, uniform nanoparticles may not be obtained as a whole, and thus, when the size of the organic semiconductor device is reduced, nonuniformity may occur between the devices.

Theoretically, organic devices are advantageous for integration because they occupy a smaller cell area (4F ² ) than conventional devices, but research to date suggests that the thermal and chemical stability of polymers and organic materials under conditions of device operation is poor. Because it is not guaranteed, it does not sufficiently satisfy the characteristics required by the highly integrated device. In addition, since the processing characteristics of the organic material are different from the existing inorganic semiconductor devices, a process technology for integration of polymer devices, such as a patterning technique, a deposition technique, an etching technique, and a low temperature electrode forming technique, suitable for the characteristics of the organic material is required.

The present invention has been devised to solve the above problems, and an object of the present invention is to provide an organic semiconductor device including an electron channel layer having a nanoparticle layer uniformly formed using nanoparticles, and a method of manufacturing the same.

According to an aspect of the present invention, an organic semiconductor device of the present invention comprises a first electrode, an electron channel layer formed on the first electrode, and an agent formed on the electron channel layer. A second particle, wherein the electron channel layer comprises: a lower organic material layer formed on the first electrode, a nanoparticle layer formed on the lower organic material layer and having nanoparticles of a predetermined size disposed at a distance from each other; It includes an upper organic material layer formed on the nanoparticle layer.

Preferably, the electron channel layer maintains a high conductivity state or a low conductivity state when no voltage is applied from the outside. The electron channel layer has a switching characteristic of switching from a high conductivity state to a low conductivity state or from a low conductivity state to a high conductivity state according to a voltage applied from the outside. The nanoparticles are metal nanoparticles made of Al, Au, Ag, Co, Ni, Fe, or a combination thereof. The size of the nanoparticles is formed in the range of 1 ~ 20nm. The separation distance between the nanoparticles has a distance that is larger or smaller than the size of the nanoparticles or within 50% of the nanoparticle size. The organic semiconductor device further includes a single molecule organic film formed between the upper organic material layer and the nanoparticle layer, and a single molecule organic film formed between the lower organic material layer and the nanoparticle layer.

According to another aspect of the invention, forming a first electrode; Forming a nanoparticle layer including nanoparticles having a predetermined size spaced apart from each other, and an electron channel layer including an upper organic layer and a lower organic layer formed on and under the nanoparticle layer on the first electrode; Forming a second electrode on the electron channel layer.

The forming of the electron channel layer may include forming the lower organic material layer on the first electrode; Forming the nanoparticle layer including the nanoparticles having a predetermined size disposed at a distance from each other on the lower organic layer; And forming the upper organic material layer on the nanoparticle layer. The nanoparticle layer, the upper organic material layer and the lower organic material layer are formed by a Langmuir-Blocking method. The nanoparticles are metal nanoparticles made of Al, Au, Ag, Co, Ni, Fe, or a combination thereof. The size of the nanoparticles is formed in the range of 1 ~ 20nm. The separation distance between the nanoparticles has a distance that is larger or smaller than the size of the nanoparticles or within 50% of the nanoparticle size. The upper organic layer and the lower organic layer are semiconducting or insulating and have an organic material having a band gap of 2 eV or more. In the forming of the first electrode and the second electrode, the first electrode and the second electrode are made of Al, Cu, Au, Pt, or doped silicon. In the step of forming the nanoparticle layer, metal nanoparticles are formed by spin coating.

Hereinafter, an organic semiconductor device and a method of manufacturing the same according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 illustrates a structure of an organic semiconductor device according to an embodiment of the present invention. Referring to FIG. 2, the organic semiconductor device 200 according to the present invention may include a first electrode 210 formed below, an electron channel layer 230 formed on the first electrode, and an agent formed on the electron channel layer 230. And two electrodes 250. The electron channel layer 230, which is a characteristic element of the present invention, includes a lower organic material layer 231 formed on the first electrode 210, a nanoparticle layer 233 and a nanoparticle layer 233 formed on the lower organic material layer 231. The upper organic material layer 235 is formed on.

Specifically, the first electrode 210 and the second electrode 250 may be formed using general electrode materials Al, Cu, Au, Pt, and doped silicon. In addition, although not shown in FIG. 2, Ti, Cr, or the like may be used to improve contact between the organic material layer and the electrode between the first electrode 210, the lower organic material layer 231, the upper organic material layer 235, and the second electrode 250. The contact layer (glue layer) or a monomolecular film can be further formed.

The lower and upper organic layers 231 and 235 may use a single molecule or a polymer having dielectric properties. In this case, the organic layers 231 and 235 formed using a single molecule or a polymer preferably have a uniform thickness of 5% or less with respect to the thickness. In order to obtain the uniform organic material layers 231 and 235, a langmuir-blodgett method is used in which a monolayer is formed on the surface of the water and accumulated on a substrate (not shown). In the present embodiment, the thickness of the organic material layers 231 and 235 is about 1 to 50 nm, and the uniformity is a thin film of less than 5%.

FIG. 3A is a view illustrating a general film fabrication step using a langmuir-blodgett method, and FIG. 3B is a detailed laminated structure of an organic semiconductor device manufactured using FIG. 3A.

Referring to FIG. 3A, first, a monomolecular or polymeric material dissolved in a hydrophobic solvent is dropped into a hydrophilic solution (water, etc.) to (organic) monomolecular film 1 (that is, a Langmuir-Blodgett films: LB). )) And ⓐ, stacked on the substrate to form a single molecular layer of molecular units ⓑ. In step ⓑ, molecular chains adsorbed on the surface of the substrate are arranged in one direction by pulling the substrate out of the polymer solution. Ⓒ and ⓓ disclose the formation of a multilayer film 2 by stacking an LB film several times when it is necessary to form several layers of organic material to increase the thickness of the thin film.

Referring to FIG. 3B, an organic semiconductor device in which an LB film formed by using the LB method of FIG. 3A is stacked is illustrated. The organic semiconductor device 200 includes a pair of electrodes 210 and 250 and an electron channel layer 230 formed between the electrodes 210 and 250. The electron channel layer 230 is formed on the lower organic layer 231 formed on the electrode 210, the monomolecular organic layer 231a fabricated by the LB method on the lower organic layer 231, and the monomolecular organic layer 231a. The nanoparticle layer 233 formed on the nanoparticle layer 233, the monomolecular organic film 235a produced by the LB method on the nanoparticle layer 233, and the upper organic compound layer 235 formed on the monomolecular organic film 235a.

The nanoparticle layer 233 is preferably made of Al, Au, Ag, Co, Ni, Fe, and the like, and uniformly between two-dimensional alignment of the nanoparticle layer 233 (that is, monomolecular organic films 231a and 235a). Nanoparticles are functionalized with a substance with a surfactant component. In this case, the surfactant plays a role of converting the hydrophilic nanoparticles into hydrophobic, and in this embodiment, mercapto-oleic acid is used as the surfactant.

The nanoparticles constituting the nanoparticle layer 233 have a suitable size of 1 to 20 nm, and in order to form the nanoparticle layer 233 between the organic material layers 231 and 235, a monomolecular film of nanoparticles functionalized by a surfactant component It is also laminated by the LB method or by the spin coating method. On the other hand, the distance between the nanoparticles of the nanoparticle layer 233 can be controlled by the length of the surfactant, preferably, the distance between the nanoparticles is ideally similar to the diameter of the nanoparticles, but the distance between the nanoparticles than the diameter of the nanoparticles Even greater or smaller within about 50% does not affect the operation of the device. The electron channel layer 230 configured as described above is formed to a thickness of about 1 to 100 nm.

The electron channel layer 230 of the organic semiconductor device 200 manufactured by the above-described method maintains a high conductance state and a low conductance state when no voltage is applied from the outside. The electron channel layer 230 has a switching characteristic of switching from a high conductivity state to a low conductivity state or a low conductivity state to a high conductivity state according to a voltage applied from the outside. Hereinafter, referring to the drawings, the switching characteristics of the organic semiconductor device according to the present invention will be described.

4 is a graph illustrating switching characteristics of the organic semiconductor device of FIG. 3B. 3B and 4, in the organic semiconductor device 200 of the present invention, when a voltage is applied to the electrodes 210 and 250 of the structure, a current may flow in a constant direction, and a high conductivity state may be obtained. ) And low conductivity state (ii) can provide a memory effect.

In the operation of the organic semiconductor device 200, when the application direction of the voltage is applied from 0 to a positive voltage, the organic semiconductor device 200 remains in a low conductivity state until a threshold voltage (Vt) is applied. Will be turned into a state. When a voltage above the threshold voltage Vt is applied, electrons are injected into the metal nanoparticles through the organic barrier, which is a dielectric, and the electron channel layer 230 is changed into a high conductivity state by the electrons injected into the metal nanoparticles. . On the other hand, in order to change the high conductivity state to the low conductivity state, a voltage in the opposite direction should be applied. When a voltage of about-Vt is applied, the high conductivity state is changed to the low conductivity state. It can be used as nonvolatile memory because each conduction state is maintained for a certain time.

In order to exhibit a reversible rapid phase transition between a high conductivity state and a low conductivity state, the organic material must be semiconducting or insulating (band gap of 2 eV or more), and the inserted metal nanoparticles may have a size of about 1 to 20 nm. When at room temperature, enough charge can be stored. In addition, when forming a thin film using uniform nanoparticles having a constant size, even if the device is reduced, the nonuniformity between the devices is reduced.

In the organic semiconductor device disclosed in the present invention, the characteristics of the channel are changed to high and low conductivity states according to an external voltage, and organic nano devices having excellent characteristics are obtained by removing non-uniformity between devices due to the reduction of devices by using uniform nanoparticles. It can be used as an element.

As mentioned above, although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the above embodiments, and various modifications may be made by those skilled in the art within the scope of the technical idea of the present invention. It is possible.

As described above, according to the above, by manufacturing an organic semiconductor device including an electron channel layer having a nanoparticle layer formed of uniform nanoparticles, the characteristics of a channel may be mutually changed to a high conductivity state and a low conductivity state according to an external voltage. In addition, the uniform nanoparticles can eliminate the nonuniformity between the devices due to the shrinking of the device can be utilized as an organic semiconductor device excellent in properties.

In addition, by using nanoparticles having a constant size distribution as a medium for charge storage, the charge storage time can be extended by varying the distance between the nanoparticles, thereby significantly increasing the time for maintaining the stored information.

Claims (17)

A first electrode, an electron channel layer formed on the first electrode, and a second electrode formed on the electron channel layer, The electron channel layer, A lower organic material layer formed on the first electrode; A nanoparticle layer formed on the lower organic material layer, the nanoparticle layer having nanoparticles of a predetermined size disposed at a distance from each other; An upper organic material layer formed on the nanoparticle layer Organic semiconductor device comprising a. The method of claim 1, The electron channel layer maintains a high conductivity state or a low conductivity state when no voltage is applied from the outside. The method of claim 1, The electron channel layer has a switching characteristic of switching from a high conductivity state to a low conductivity state or from a low conductivity state to a high conductivity state according to a voltage applied from the outside. The method of claim 1, The nanoparticle is an organic semiconductor device which is a metal nanoparticle consisting of Al, Au, Ag, Co, Ni, Fe or a combination thereof. The method of claim 1, The size of the nanoparticles is an organic semiconductor device formed in the range of 1 ~ 20nm. The method of claim 5, The distance between the nanoparticles is an organic semiconductor device having a distance greater than or equal to the size of the nanoparticles or within 50% of the size of the nanoparticles. The method of claim 1, The organic semiconductor device further comprises a single molecule organic film formed between the upper organic material layer and the nanoparticle layer. The method of claim 1, The organic semiconductor device further comprises a monomolecular organic film formed between the nanoparticle layer and the lower organic material layer. Forming a first electrode; Forming a nanoparticle layer including nanoparticles having a predetermined size spaced apart from each other, and an electron channel layer including an upper organic layer and a lower organic layer formed on and under the nanoparticle layer on the first electrode; Forming a second electrode on the electron channel layer Method for manufacturing an organic semiconductor device comprising a. The method of claim 9, Forming the electron channel layer, Forming the lower organic material layer on the first electrode; Forming the nanoparticle layer including the nanoparticles having a predetermined size disposed at a distance from each other on the lower organic layer; And Forming the upper organic material layer on the nanoparticle layer Method for manufacturing an organic semiconductor device comprising a. The method of claim 9, The nanoparticle layer, the upper organic material layer and the lower organic material layer is a method of manufacturing an organic semiconductor device is formed by the Langmuir-Blocking method. The method of claim 9, The nanoparticle is a method for producing an organic semiconductor device which is a metal nanoparticle consisting of Al, Au, Ag, Co, Ni, Fe or a combination thereof. The method of claim 9, The nanoparticle size is formed in the range of 1 ~ 20nm manufacturing method of an organic semiconductor device. The method of claim 13, The separation distance between the nanoparticles is a method of manufacturing an organic semiconductor device having a distance equal to or smaller than or equal to the size of the nanoparticles within 50% of the size of the nanoparticles. The method of claim 9, And the upper organic material layer and the lower organic material layer are semiconducting or insulating and have an organic material having a band gap of 2 eV or more. The method of claim 9, In the forming of the first electrode and the second electrode, And the first electrode and the second electrode are made of Al, Cu, Au, Pt or doped silicon. The method of claim 10, In the step of forming the nanoparticle layer, a method of manufacturing an organic semiconductor device to form metal nanoparticles by a spin coating method.

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