KR100969478B1 - Method of fabricating the nanodevice using PDMS - Google Patents

Abstract

The present invention relates to a method for manufacturing a nano device using PDMS (Polydimethylsiloxane), by providing a process for uniformly aligning the nano structure selectively on the electrode pattern using a PDMS (Polydimethylsiloxane) pattern, manufacturing a conventional nano-structure device The present invention relates to a process that is simpler than a method, short in process time, low in manufacturing cost, and capable of processing even on a large scale, and also to easily implement nano devices such as gas, bio and optical sensors.

Description

Method of fabricating nanodevices using PDMS {Method of fabricating the nanodevice using PDMS}

The present invention relates to a method for manufacturing a nano device using PDMS (Polydimethylsiloxane), most of the process of forming a nano device using a nano-structure takes a long time, solves the problem of expensive manufacturing cost, the conventional nano-structure device The present invention relates to a process that is simpler than a manufacturing method and that enables processing on a large scale and to easily implement nano devices such as gas, bio and optical sensors.

Recently, Carbon Nanotubes (CNT), Oxide Nanotubes, Nanorods, Nanowires, Nanosheets, Nanoribbons, Nanoribbons or Nano-Thick Hollow Particles (Hollow) Research into devices using various types of low-dimensional nanostructures, such as spheres, is being actively conducted. Such nanostructures have attracted great attention not only for their excellent properties such as physical and chemical properties, but also for being able to realize various effects of nanomaterials while being a basic unit useful for constructing nanodevices. .

These nanostructures are synthesized by laser ablation, sputtering, chemical vapor depositon, or sol-gel methods. In addition, it is possible to improve the characteristics of the device by adding impurities to the nanostructure, or synthesized in a heterostructure or core shell structure.

In addition, research on nano devices forming field effect transistors (FETs), lasers, chemical sensors, bio sensors, and the like using nanostructures is being conducted.

However, despite the physical or chemical properties of the nanostructures, it is difficult to realize practical devices due to the incompleteness of dispersion, alignment, and patterning.

The most typical method of manufacturing a nano device is to use a conventional semiconductor process to pattern materials such as silicon through microlithography and etching processes. In addition, there is a top-down method of directly fabricating a device by an etching process, and a VLS (Vapor-Liquid Solid) growth method using a metal catalyst on a substrate, a sol-gel method, or a VS (Vaper) method. After the nanostructures are synthesized by a method such as a -solid method, an electrode is formed on a substrate, and a bottom-up method of fabricating nanodevices by dispersing and aligning the synthesized nanostructures at a specific position is provided.

Here, in the case of the top-down process, there is an advantage in that the device can be manufactured in a desired size at a desired position, but it is inefficient in terms of price competition because the process for patterning is complicated and the equipment is expensive. In addition, the materials used are limited, which makes them suitable for current silicon-based semiconductor processes.

In contrast, the bottom-up method involves selectively growing nanostructures by directly using a metal catalyst on a substrate and synthesizing the nanostructures first, and then aligning the nanostructures through a post process such as electrode deposition. Can be divided into ways.

In the method of forming a device by selectively growing a nanostructure directly on a substrate using a metal catalyst, the nanostructure is vertically grown using a catalyst on the substrate, and then an electrode connected to the nanostructure is formed. There is a problem that is difficult. In addition, it is difficult not only to form a nanostructure grown vertically at a uniform height in a uniform area but also to produce a large amount of it. In addition, in terms of device characteristics, device characteristics may be deteriorated by a buffer layer formed when synthesizing a nanostructure.

Next, the nanostructures are first synthesized, and then the nanostructures are aligned through post-processing, such as electrode deposition. ) To control the exact location of the single nanostructure and to align the nanostructure on the substrate. This process is easier than growing nanostructures, but it is difficult to commercialize because of the slow alignment speed and the use of expensive equipment.

In order to solve this problem, the nanostructures are synthesized, and then aligned with the nanostructures, Langmuir-Blodgett (LB), microfluidic, electrophoresis, or self-assembled monolayers ( Self-assembly monolayer (SAM) is used.

The most representative method is the Lang Moore-Blodge method, in which the non-volatile, water-insoluble nanowires or nanorods are dispersed in water when the adhesion to the surface of the nanowire or nanorod is greater than the cohesion between the molecules. This is an effective way to align nanostructures. This has been studied in the Peidong Yang group (CHEMPHYSCHEM, 3, 503-506, 2002). The Langmore-Blozet method has a problem in that the electrode structure is placed on a solution, and aggregation of nanostructures may occur when drying.

In the self-assembly molecular thin film method, an organic active material is spontaneously bonded onto a substrate by immersing a solution in which silicon, thiol-based or amine-based organic active materials are dissolved in a substrate such as silicon oxide, gold, or platinum. Monolayers are formed and nanowires are patterned. Even in this method, the electrode structure must be put in the solution, it takes a long time, and there is a problem in that the material that can be selectively placed on the electrode is largely restricted.

As described above, most of the processes for forming nanodevices using nanostructures take a long time, and in order to actually fabricate devices, the ordered nanostructures must be selectively transferred to the devices, which requires expensive raw materials and additional processes. This is inefficient and inefficient, and it is almost impossible to apply it especially when the scale of the substrate is large.

In order to solve the above problems, the present invention proposes a process of uniformly aligning nanostructures selectively on an electrode by using a polydimethylsiloxane (PDMS) pattern, thereby simplifying the process and making a large scale than a conventional nanostructure device manufacturing method. It is an object of the present invention to provide a method of aligning nanostructures using PDMS (Polydimethylsiloxane) and a method of manufacturing nanodevices using the same, which enables the process and easily implements nanodevices such as gas, bio and optical sensors.

Method of manufacturing a nano device according to an embodiment of the present invention

Forming a polydimethylsiloxane (PDMS) for selectively exposing the electrode pattern on the semiconductor substrate on which the electrode pattern is formed, and on the exposed electrode pattern It is characterized by forming a nanostructure.

Here, the nanostructure is characterized in that to form a network by selectively connecting the electrode pattern.

In addition, the manufacturing method of the nano device according to another embodiment of the present invention

Forming an oxide layer on the silicon substrate, forming an electrode pattern on the oxide layer, and forming a polydimethylsiloxane (PDMS) pattern on the oxide layer to expose a region where a nanostructure connected to the electrode pattern is to be formed. Selectively dropping distilled water containing the nanostructures in a region between the PDMS patterns, evaporating the distilled water to form the nanostructures on the electrode pattern, and removing the PDMS patterns. Characterized in that it comprises a step.

Here, the nanostructures are carbon nanotubes (CNT), oxide nanotubes, nanorods, nanowires, nanosheets, nanoribbons, nanoribbons, nanothickness. It characterized in that it uses any one selected from the hollow sphere (Hollow sphere) and a mixture thereof, the step of forming the polydimethylsiloxane (PDMS) pattern is the organic material such as xylene or toluene (xylene) or toluene (tolune) Dissolving in a solvent, adding DMmethoxy (dymethoxy phenyl acetophenone) as a curing agent to the PDMS solution, applying a PDMS solution with the curing agent on top of the oxide film, curing the PDMS solution, and Patterning the cured PDMS using a laser beam, wherein adding the curing agent to the PDMS solution comprises the PDMS solution and the It characterized by performing a mixture in a weight percentage of 1: the percentage of the agent 10.

In addition, the manufacturing method of the nano device according to another embodiment of the present invention

Forming an oxide layer on the silicon substrate, a polydimethylsiloxane (PDMS) pattern exposing a region where the nanostructure is to be formed on the oxide layer, and selectively distilled water including the nanostructure in the region between the PDMS pattern Dropping, evaporating the distilled water to form the nanostructures on the oxide film, removing the PDMS pattern, and forming an electrode pattern connected to the nanostructures. .

The alignment of nanostructures using PDMS (Polydimethylsiloxane) according to the present invention and a method of fabricating nanodevices using the same are performed by selectively aligning the nanostructures uniformly on an electrode using a PDMS (Polydimethylsiloxane) pattern, and thus, a method of manufacturing nanostructure devices. It can simplify the process and provide the effect of reducing time and cost. In addition, the present invention enables the mass production of nano devices even at a wafer scale of 4 inches or more, thereby providing an effect of improving the yield of the nano device manufacturing process.

In more detail, the present invention is divided into four steps as follows. First, manufacturing an electrode pattern on a substrate, manufacturing a polydimethylsiloxane (PDMS) pattern on the substrate, selectively aligning the nanostructures on the substrate, and applying the aligned nanostructures to form a nanodevice .

Here, PDMS is a transparent inert polymer having a very low surface energy, easy change of form, and hydrophobic material.

First, PDMS stably adheres to a relatively large substrate area, which is equally satisfied for uneven surfaces.

Second, since PDMS has low interfacial free energy, adhesion does not occur well when molding with other polymers.

Third, PDMS is homogeneous isotropic and optically transparent up to 300 nm thick.

Fourthly, PDMS is very durable and does not cause degradation of properties even after curing for a very long time.

1A to 1D are schematic diagrams illustrating a manufacturing process of a nano device using a PDMS pattern according to a first embodiment of the present invention.

Referring to FIG. 1A, oxide layers SiO ₂ and 120 are formed on the silicon substrate 100. At this time, the reason for forming the oxide film 120 is to allow the PDMS formed in the subsequent process to be easily bonded or peeled off the silicon substrate.

Next, a lithography process is performed to form a comb source / drain, and an electrode pattern is formed by using a Ti / Pt electron beam evaporation or sputtering process. 130 is manufactured. At this time, the overall size of the electrode pattern 130 is 500 × 500㎛, it is preferable that the minimum spacing between the electrode pattern is formed to be 5 ~ 20㎛.

Referring to FIG. 1B, the PDMS and the curing agent are uniformly mixed in a ratio of 10: 1 and then coated on the oxide layer 120 having the electrode pattern 130 formed thereon. In this case, in order to impart proper viscosity to PDMS, one dissolved in an organic solvent such as xylene or toluene is used, and DMAP (dymethoxy) is used for hardening and polymerizing. Materials such as phenyl acetophenone) are used as hardeners.

Next, the PDMS is cured at a temperature of 60 ^° C. for 12 hours.

Next, the PDMS pattern 140 is formed by cutting a portion of the electrode to which the nanostructure is to be formed with a laser by referring to the design drawing of the electrode pattern. Therefore, the finally produced PDMS pattern 140 becomes a pattern having grooves only in the portion where the nanostructure is to be deposited. At this time, the size of the groove can be up to several μm to several mm according to the design of the pattern of the sensor, and accordingly the size of the PDMS pattern 140 can be adjusted.

Referring to FIG. 1C, a solution 150 in which nanostructures such as nanowires, nanotubes, nanoparticles, or carbon nanotubes (CNT) is dispersed in distilled water is dropped into a groove using a micropipette.

Referring to FIG. 1D, the solution 150 dropped in the groove is naturally dried and the PDMS pattern 140 is removed.

Through this process, the nanostructure 160 is selectively formed on the portion exposed by the PDMS pattern 140. This is because the PDMS pattern 140 has hydrophobicity with respect to the oxide film 120 and the solution 150, so that the solution 150 does not spread as if it has hydrophile. When evaporated, the nanostructures 160 are selectively formed on the electrode pattern 130.

2 is a perspective view illustrating a nano device according to a first embodiment of the present invention.

Referring to FIG. 2, an oxide film 120 is formed on the silicon substrate 100, an electrode pattern 130 is formed on the oxide film, and nanostructures 160 are selectively formed on the electrode pattern 130. . At this time, since the amount of the solution is dropped depending on the size and thickness of the PDMS pattern 140, by using this principle it is possible to adjust the density of the nanostructure (160). The nanostructures 160 formed as described above are connected to the electrode pattern 130 to act as nano devices having electrical characteristics.

In addition, a method of forming an electrode pattern using a mask including an electrode pattern after depositing a nanostructure and then forming a PDMS pattern first may be used as opposed to the above-described method.

3A to 3D are schematic views illustrating a manufacturing process of a nano device using a PDMS pattern according to a second embodiment of the present invention.

Referring to FIG. 3A, an oxide film 220 is formed on the silicon substrate 200, and a PDMS pattern 240 is formed on the oxide film 220. At this time, the oxide film 220 is formed so that the PDMS pattern 240 is easily adhered and then easily peeled off.

Referring to FIG. 3B, a solution 250 including nanostructures is dropped in a groove formed by the PDMS pattern 240.

Referring to FIG. 3C, the solution 250 is dried, and the PDMS pattern 240 is removed to selectively form the nanostructures 260 on the oxide film 220.

Referring to FIG. 3D, an electrode pattern 280 connected to the nanostructure 260 is formed using a mask 270 defining electrode patterns.

4 is a perspective view illustrating a nano device according to a second exemplary embodiment of the present invention.

Referring to FIG. 4, a mask 270 defining an electrode pattern is used after removing the PDMS pattern 240. That is, in the first embodiment, the electrode pattern is formed after the oxide film forming process. In the second embodiment, the electrode pattern 280 is formed after the PDMS pattern 240 removal step. As such, the order of the electrode pattern forming process can be arbitrarily changed as necessary, and the operation of the nano device is not impeded at all.

5 is a schematic diagram illustrating a method of manufacturing a nano device according to a third embodiment of the present invention.

Referring to FIG. 5, various solutions containing precursor materials of a gas sensor are dropped into an electrode array coated with PDMS, and when heat-treated with a heater, simultaneously analyzing and determining complex stoichiometry such as human smell. It demonstrates that we can fabricate intelligent artificial olfaction sensor, a multifunctional chemical sensing nano device.

After forming an oxide film (not shown) on the silicon substrate 340, the electrode patterns 320 of the compound function chemical sensing element are formed on the oxide film.

Next, after forming the PDMS pattern 300, by dropping the nanostructure 360 on the electrode pattern using a micropipette 350 that can systematically control nanosol or nanostructures of various compositions, artificial olfactory The sensor can be manufactured more easily.

6 is a plan view illustrating a nano device selectively formed according to a fourth embodiment of the present invention.

Referring to FIG. 6, a sensor array process in which the nanostructure 440 is selectively arranged on the sensor electrode 430 or the electric heater 420 formed on the semiconductor substrate 400 is illustrated.

Here, by adding a catalyst such as a noble metal in a solution dropping method in a state where the nanostructures are selectively arranged, gas sensitivity and selectivity can be improved.

First, tin oxide nanowires (SnO ₂ nanowires) synthesized by a metal thermal evaporation process using a tin metal powder are selectively deposited on an electrode pattern using a PDMS pattern according to the present invention.

7 is a graph showing a nano device manufactured according to the fifth embodiment of the present invention and its electrical characteristics.

The electron micrograph of FIG. 7 shows that the tin oxide nanowires (SnO ₂ nanowires) are uniformly formed in a network state on the electrode.

8 is a graph showing a nano device manufactured according to a sixth embodiment of the present invention and its electrical characteristics.

The electron micrograph of FIG. 8 shows that zinc oxide nanosheets synthesized by a carbon thermal reduction process are selectively deposited on electrodes, and thus, are uniformly formed in a network state.

In addition, the graphs of FIGS. 7 and 8 are applied to the nano-devices of FIGS. 7 and 8 by applying a source-drain voltage between -5 to 5V using a Keithley 4200 series source meter. I _DS ) -Voltage (V _DS ) characteristics are measured.

When the contact between the electrode pattern and the nanowire or the nanosheet is not good, a rectifying contact occurs in the current (I _DS ) -voltage (V _DS ) characteristics or the current appears very small. The graph shows that the contact between the nanowire or the nanosheet and the electrode is very good because it follows the Ohm's law in which the rate of change of the current (I _DS ) -voltage (V _DS ) changes almost linearly. .

9A and 9B are graphs illustrating the response characteristic of the nano device according to the fifth embodiment of the present invention to NOx gas.

Gas response characteristics were measured by the following method. A quartz tube (40 × 600 mm) was installed in a high temperature electric furnace, and a gas sensor was placed in the center of the quartz tube. The total flow rate of the tube is fixed at 500 sccm.

Next, measure the base resistance by flowing 500sccm of air, mix the measured gases using two MFCs, and measure the measured gas on / off by using 4-way valve. . In this case, the sensitivity (Senstivity) when said resistance (Resistance) of the base resistance (Resistance) a R _a, measured gas in air is represented by R _g R _g / R _a. That is, R _g / R _a represents the change in resistance (R _g ) with respect to NOx gas concentration over time based on the base resistance (R _a ), and the reaction and recovery time (Time) is the initial resistance (R _a). ) Is calculated as the time range at 90% after subtraction of the resistance (R _g ).

FIG. 9A is a graph of measuring the concentration (ppm) of NOx gas using a change in resistance value with time at a temperature of 250 ° C. FIG.

In the case of the nanosensor device of the present invention using the SnO ₂ nanowire network, it can be seen that the resistance of the sensor increases significantly when exposed to NO ₂ .

Referring to FIG. 9B, gas sensing characteristics of 0.2 to 5 ppm of NOx were measured, indicating that the sensitivity was 2.4 at 0.2 ppm and 25.3 at 5 ppm. This results in higher sensitivity at lower concentrations than previously published, and is the result of nanowires being well dispersed and easily reacting with gas.

10A and 10B are graphs illustrating a response characteristic of NOx gas of a nano device using a ZnO nanosheet according to a sixth embodiment of the present invention.

Referring to FIGS. 10A and 10B, gas sensitivity characteristics of 0.2 to 5 ppm NOx gas were measured at a temperature of 300 ° C., and the sensitivity was 1.2 at 5 ppm and 10.8 at 5 ppm. Therefore, it can be seen that the nanosheets are uniformly well dispersed in the electrode pattern.

11A and 11B illustrate changes in current when a voltage of −5 to 5 V is applied and whether current is constant when a 1 V voltage is applied to the nano device according to the sixth exemplary embodiment of the present invention. Are graphs.

Referring to FIGS. 11A and 11B, the UV-sensitized characteristics of the nanodevices using the ZnO nanosheets are shown, when exposed to monochromatic UV light having a wavelength of 325 nm (Under UV 325 nm) and when not exposed (In the Dark). When exposed to ultraviolet rays (Under UV 325nm) on the graph is shown as a graph with a slope, when not exposed (In the Dark), there is almost no slope.

Referring to FIG. 11B according to the sixth embodiment of the present invention, it can be seen that the nano device exhibits an increase in current from 4.39 to 136.2 mA when a 1 V voltage is applied between the source and the drain. Therefore, when the nano device of the present invention is exposed to the monochromatic UV light of a specific 325 nm using this, since the amount of change of the current is changed by about 20 times or more, it is possible to use it as an optical device capable of detecting the presence or absence of ultraviolet light.

As described above, the nano device manufactured by the present invention can be used as a gas sensor, an optical device, a bio device, and the like.

1A to 1D are schematic views illustrating a manufacturing process of a nano device using a PDMS pattern according to the first embodiment of the present invention.

2 is a perspective view of a nano device according to a first embodiment of the present invention;

3A to 3D are schematic views illustrating a manufacturing process of a nano device using a PDMS pattern according to a second embodiment of the present invention.

4 is a perspective view showing a nano device according to a second embodiment of the present invention;

5 is a schematic view showing a method of manufacturing a nano device according to a third embodiment of the present invention.

6 is a plan view showing a nano device selectively formed according to the fourth embodiment of the present invention.

Figure 7 is a graph showing the nanodevices and their electrical characteristics produced in accordance with a fifth embodiment of the present invention.

8 is a graph showing a nano device and its electrical characteristics manufactured according to the sixth embodiment of the present invention.

9A and 9B are graphs illustrating the response characteristic of the nano device according to the fifth embodiment of the present invention with respect to NOx gas.

10A and 10B are graphs showing the response characteristic of the nano device according to the sixth embodiment of the present invention for NOx gas.

11A and 11B are graphs illustrating changes in current according to 325 nm short wavelength of a nano device according to a sixth exemplary embodiment of the present invention.

Claims (7)

Forming a polydimethylsiloxane (PDMS) for selectively exposing the electrode pattern on the semiconductor substrate on which the electrode pattern is formed, and on the exposed electrode pattern A method of manufacturing a nano device, characterized by forming a nano structure. The method of claim 1, The nanostructure is a method of manufacturing a nano device, characterized in that to form a network by selectively connecting the electrode pattern. Forming an oxide film on the silicon substrate; Forming an electrode pattern on the oxide film; Forming a polydimethylsiloxane (PDMS) pattern on the oxide layer to expose a region where a nanostructure connected to the electrode pattern is to be formed; Selectively dropping distilled water including the nanostructure into a region between the PDMS patterns; Evaporating the distilled water to form the nanostructure on the electrode pattern; And The method of manufacturing a nano device comprising the step of removing the PDMS pattern. The method of claim 3, wherein The nanostructures include carbon nanotubes (CNT), oxide nanotubes, nanorods, nanowires, nanosheets, nanoribbons, nano-thick hollows. Particles (Hollow sphere) and a method for producing a nano device, characterized in that any one selected from a mixture thereof. The method of claim 3, wherein Forming the polydimethylsiloxane (PDMS) pattern is Dissolving the PDMS in an organic solvent such as xylene or toluene; Adding dymethoxy phenyl acetophenone (DMAP) to the PDMS solution as a curing agent; Applying a PDMS solution with the curing agent on the oxide layer; Curing the PDMS solution; And And patterning the cured PDMS using a laser beam. The method of claim 5, Adding the hardener to the PDMS solution Method for producing a nano-device, characterized in that the mixture of the PDMS solution and the curing agent in a weight percent of 10: 1. Forming an oxide film on the silicon substrate; Forming a polydimethylsiloxane (PDMS) pattern exposing a region where a nanostructure is to be formed on the oxide layer; Selectively dropping distilled water including the nanostructure into a region between the PDMS patterns; Evaporating the distilled water to form the nanostructure on the oxide film; Removing the PDMS pattern; And And forming an electrode pattern connected to the nanostructure.

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