TWI476837B - Method for making thin film transistor - Google Patents

Description

Method for preparing thin film transistor

The invention relates to a method for preparing a thin film transistor, in particular to a method for preparing a thin film transistor based on a carbon nanotube.

Thin Film Transistor (TFT) is a key electronic component in modern microelectronics technology and has been widely used in flat panel displays and other fields. The thin film transistor mainly includes a gate, an insulating layer, a semiconductor layer, a source, and a drain. The source and the drain are spaced apart from each other and electrically connected to the semiconductor layer, and the gate is insulated from the semiconductor layer and the source and the drain by an insulating layer. The semiconductor layer is located in a region between the source and the drain to form a channel region. The gate, the source and the drain of the thin film transistor are each composed of a conductive material, which is generally a metal or an alloy. When a voltage is applied to the gate, the channel region in the semiconductor layer spaced apart from the gate through the insulating layer accumulates carriers, and when the carrier accumulates to a certain extent, the source drain is electrically connected to the semiconductor layer. Turned on so that current flows from the source to the drain. In practical applications, it is desirable to obtain a thin film transistor having a large switching current ratio. Factors Affecting the Switching Current Ratio In addition to the preparation process of the thin film transistor, the carrier mobility of the semiconductor material in the thin film transistor layer is one of the most important factors affecting the switching current ratio.

In the prior art, a material for forming a semiconductor layer in a thin film transistor is an amorphous germanium, a polycrystalline germanium or an organic semiconductor polymer or the like (R.E.I. Schropp, B. Stannowski, J.K. Rath, New challenges in thin film transistor research, Journal of Non-Crystalline Solids, 299-302, 1304-1310 (2002)). The preparation technique of amorphous germanium thin film transistor with amorphous germanium as the semiconductor layer is relatively mature. However, in the amorphous germanium thin film transistor, since the semiconductor layer usually contains a large number of dangling bonds, the mobility of the carrier is low. , resulting in a slower response of the thin film transistor. A thin film transistor in which polycrystalline germanium is used as a semiconductor layer has a higher carrier mobility than a thin film transistor in which amorphous germanium is used as a semiconductor layer, and thus the response speed is also fast. However, the low-temperature preparation of the polycrystalline germanium thin film transistor is relatively high, the method is complicated, the large-area preparation is difficult, and the off-state current of the polycrystalline germanium thin film transistor is large. Compared with the above-mentioned conventional inorganic thin film transistor, the organic thin film transistor using the organic semiconductor as the semiconductor layer has the advantages of low cost and low preparation temperature, and the organic thin film transistor has high flexibility. However, since the organic semiconductor polymer is mostly skip-type conduction at normal temperature, it exhibits high resistivity and low carrier mobility, so that the response speed of the organic thin film transistor is slow.

Nano carbon tubes have excellent mechanical and electrical properties. The carbon nanotubes may exhibit metallic or semiconducting properties as the carbon nanotubes are spirally changed. Semiconducting carbon nanotubes have a high carrier mobility (generally up to 1000~1500cm ² V ^-1 s ^-1 ) and are ideal materials for the preparation of transistors. It has been reported in the prior art to form a carbon nanotube layer as a semiconductor layer of a thin film transistor using a semiconducting carbon nanotube. The method for preparing a thin film transistor using the carbon nanotube layer as a semiconductor layer mainly includes the following steps: dispersing a carbon nanotube powder by ultrasonic treatment in an organic solvent; and performing carbon nanotube printing on the carbon nanotube The organic solvent mixture is printed on the insulating substrate, and after the organic solvent is volatilized, a carbon nanotube layer is formed on the predetermined position of the insulating substrate; the source is formed on the carbon nanotube layer by depositing and etching the metal thin film And bungee; depositing a layer of tantalum nitride on the carbon nanotube layer to form an insulating layer; and depositing a metal film on the insulating layer to form a gate. Since the carbon nanotube powder is easily agglomerated, an additional dispersion step is required. However, the carbon nanotubes are not well dispersed by ultrasonic dispersion, resulting in a non-uniform distribution of the carbon nanotubes in the semiconductor layer formed by inkjet printing, thereby affecting the performance of the thin film transistor. In addition, the preparation of the carbon nanotube layer by means of inkjet printing is complicated, which is not conducive to reducing the production cost of the thin film transistor.

In view of this, it is necessary to provide a method for preparing a thin film transistor which is simple in method and suitable for low-cost mass production.

A method for preparing a thin film transistor, comprising the steps of: preparing a carbon nanotube raw material; adding the above carbon nanotube raw material to a solvent and performing a flocculation treatment to obtain a nano carbon tube floc structure; The carbon tube floc structure is separated from the solvent, and the carbon nanotube floc structure is shaped to obtain a carbon nanotube film, which is composed of a plurality of unfunctionalized carbon nanotubes Forming; laying the above carbon nanotube film on the surface of an insulating substrate to form a carbon nanotube layer; forming a source and a drain at intervals, and electrically connecting the source and the drain to the carbon nanotube layer Forming an insulating layer on the surface of the carbon nanotube layer; and forming a gate on the surface of the insulating layer to obtain a thin film transistor.

A method for preparing a thin film transistor, comprising the steps of: preparing a carbon nanotube raw material; adding the above carbon nanotube raw material to a solvent and advancing Performing a flocculation treatment to obtain a nano carbon tube floc structure; separating the above carbon nanotube floc structure from a solvent, and shaping the carbon nanotube floc structure to obtain a carbon nanotube film, The carbon nanotube film is composed of a plurality of unfunctionalized carbon nanotubes; an insulating substrate is provided; a gate is formed on the surface of the insulating substrate; an insulating layer is formed to cover the gate; and the nanocarbon is laid The tube film forms a carbon nanotube layer on the surface of the insulating layer; and a source and a drain are formed at intervals, and the source and the drain are electrically connected to the carbon nanotube layer.

A method for preparing a thin film transistor comprises the steps of: preparing a carbon nanotube raw material; adding the above carbon nanotube raw material to a solvent and performing a flocculation treatment to obtain a nano carbon tube floc structure; The carbon tube floc structure is separated from the solvent, and the carbon nanotube floc structure is shaped to obtain a carbon nanotube film, and the carbon nanotube film is composed of a plurality of unfunctionalized carbon nanotubes. Laying the above-mentioned carbon nanotube film on the surface of an insulating substrate, patterning the carbon nanotube film to form a plurality of carbon nanotube layers; forming a plurality of sources and a plurality of drains at intervals, and making each of the above The carbon nanotube layers are electrically connected to a source and a drain; an insulating layer is formed on the surface of each carbon nanotube layer; and a gate is formed on the surface of each insulating layer to obtain a plurality of thin film transistors.

The method for preparing a thin film transistor and a thin film transistor array provided by the embodiments of the present technical solution has the following advantages: First, a carbon nanotube film can be obtained as a semiconductor layer by a flocculation treatment, which does not require an additional dispersion treatment step, and simplifies the preparation. The process reduces the production cost of thin film transistors and thin film transistor arrays. Second, the carbon nanotube film obtained after the flocculation treatment has a certain viscosity, and the carbon nanotube film can be directly adhered. The method is simple and low in cost. Therefore, the method for preparing the thin film transistor provided by the technical solution has the advantages of low cost, environmental protection and energy saving. Third, the carbon nanotubes in the carbon nanotube layer are intertwined and evenly distributed. Therefore, when the carbon nanotube layer is used as a semiconductor layer, a high carrier is provided between the source and the drain. The advantages of moving rate and mechanical performance are good.

The technical solution will be further described in detail below with reference to the accompanying drawings.

Referring to FIG. 1 and FIG. 2, a first embodiment of the present technical solution provides a method for preparing a top gate type thin film transistor 10, which mainly includes the following steps:

Step 1: Prepare a carbon nanotube raw material. The method for preparing the carbon nanotube raw material comprises the following steps: First, preparing a carbon nanotube array formed on a substrate, preferably, the array is a super-sequential carbon nanotube array.

The carbon nanotube array provided by the embodiments of the present technical solution is one of a single-walled carbon nanotube array, a double-walled carbon nanotube array, and a multi-walled carbon nanotube array. The method for preparing the carbon nanotube array adopts a chemical vapor deposition method, and the specific steps thereof include: (a) providing a flat substrate, the substrate may be selected from a P-type or N-type germanium substrate, or a germanium substrate having an oxide layer formed thereon. Preferably, the present embodiment adopts a 4-inch germanium substrate; (b) uniformly forms a catalyst layer on the surface of the substrate, and the catalyst layer material may be selected from iron (Fe), cobalt (Co), nickel (Ni) or any combination thereof. One of the alloys; (c) annealing the substrate on which the catalyst layer is formed in air at 700 ° C to 900 ° C for about 30 minutes to 90 minutes; (d) placing the treated substrate in a reaction furnace, It is heated to 500 ° C ~ 740 ° C in a protective gas atmosphere, and then reacted with a carbon source gas for about 5 minutes to 30 minutes to grow to obtain a carbon nanotube array having a height greater than 100 μm. The carbon nanotube array is a plurality of pure carbon nanotube arrays formed by a plurality of carbon nanotubes which are parallel to each other and perpendicular to the substrate. Due to the long length of the carbon nanotubes, some of the carbon nanotubes are entangled with each other. The carbon nanotube array is substantially the same area as the above substrate. The super-sequential carbon nanotube array contains substantially no impurities such as amorphous carbon or residual catalyst metal particles, etc., by controlling the growth conditions described above.

In the embodiment of the technical solution, the carbon source gas may be a chemically active hydrocarbon such as acetylene, ethylene or methane. The preferred carbon source gas in the embodiment of the technical solution is acetylene; the shielding gas is nitrogen or an inert gas, and the technical solution is The preferred shielding gas for the examples is argon.

It can be understood that the carbon nanotube array provided by the embodiments of the present technical solution is not limited to the above preparation method.

Secondly, the above-mentioned carbon nanotube array is scraped off from the substrate by using a blade or other tool to obtain a carbon nanotube raw material, wherein the above-mentioned carbon nanotubes are kept in a state of being entangled to some extent. In the carbon nanotube raw material, the length of the carbon nanotube is greater than 100 micrometers, and preferably, the length of the carbon nanotube is greater than 10 micrometers.

Step 2: adding the above carbon nanotube raw material to a solvent and performing a flocculation treatment to obtain a nano carbon tube floc structure.

In the embodiment of the technical solution, the solvent may be selected from water, a volatile organic solvent or the like. The flocculation treatment can be carried out by a method such as ultrasonic dispersion treatment or high-intensity stirring. Preferably, the embodiment of the technical solution adopts ultrasonic dispersion 10~30 minutes. Due to the extremely large specific surface area of the carbon nanotubes, there is a large van der Waals force between the intertwined carbon nanotubes. The above flocculation treatment does not completely disperse the carbon nanotubes in the carbon nanotube raw material in the solvent, and the carbon nanotubes are mutually attracted and entangled by the van der Waals force to form a network structure.

In the third step, the above-mentioned carbon nanotube floc structure is separated from the solvent, and the carbon nanotube floc structure is shaped to obtain a carbon nanotube film.

In the embodiment of the technical solution, the method for separating the carbon nanotube floc structure comprises the following steps: pouring the solvent containing the carbon nanotube floc structure into a funnel with a filter paper; A period of time is obtained to obtain a separate carbon nanotube floc structure in which the carbon nanotubes are intertwined.

In the embodiment of the technical solution, the setting process specifically includes the following steps: spreading the carbon nanotube floc structure according to a predetermined shape; applying a certain pressure to the expanded carbon nanotube floc structure; The carbon nanotube film is obtained by drying the solvent remaining in the nano carbon tube floc structure or naturally evaporating the solvent.

It can be understood that the embodiment of the technical solution can control the thickness and the areal density of the carbon nanotube film by controlling the area spread by the carbon nanotube floc structure. The larger the area of the carbon nanotube floc spread, the smaller the thickness and areal density of the carbon nanotube film. Referring to FIG. 3 , a carbon nanotube film obtained in an embodiment of the present invention, wherein a plurality of carbon nanotubes in the carbon nanotube film are intertwined to form a microporous structure, which is prepared by the embodiment of the present technical solution. Nano carbon nanotube film including intertwined carbon nanotubes The carbon nanotubes are mutually attracted and entangled by the van der Waals force to form a network structure, so the carbon nanotube film has good toughness. In the carbon nanotube film, the carbon nanotubes are isotropic, uniformly distributed, and randomly arranged to form a large number of microporous structures having a pore diameter of less than 10 μm. The carbon nanotube film has a thickness of from 0.5 nm to 100 μm.

In addition, the above separation and sizing treatment step can also directly obtain a carbon nanotube film by suction filtration, specifically comprising the steps of: providing a microporous membrane and an extraction funnel; and the above-mentioned carbon nanotube containing flocculation The solvent of the structure is poured into the suction funnel through the microfiltration membrane; after suction filtration and drying, a carbon nanotube film is obtained. The microporous membrane is a filter membrane having a smooth surface and a pore size of 0.22 μm. Since the suction filtration method itself will provide a large gas pressure on the carbon nanotube floc structure, the carbon nanotube floc structure directly forms a uniform carbon nanotube film by suction filtration. Moreover, since the surface of the microporous membrane is smooth, the carbon nanotube film is easily peeled off.

Since the carbon nanotubes in the super-sequential carbon nanotube array provided in the first step of the first embodiment of the technical solution are very pure, and because the specific surface area of the carbon nanotube itself is very large, the carbon nanotube film is It has a certain viscosity.

Step 4: Laying the above-mentioned carbon nanotube film on the surface of an insulating substrate 110 to form a carbon nanotube layer 140 as a semiconductor layer of the thin film transistor 10. Specifically, the method includes the following steps: providing an insulating substrate 110; and laying the carbon nanotube film on the surface of the insulating substrate 110.

The material of the insulating substrate 110 may be selected from the materials of the substrate in a large scale integrated circuit. The shape of the insulating substrate 110 is not limited, and may be square, circular, or the like. Any shape. The size of the insulating substrate 110 is not limited, and may be determined according to actual conditions. The insulating substrate 110 has a flat surface. Specifically, the material of the insulating substrate 110 may be a hard material such as a P-type or N-type germanium, a germanium formed with an oxide layer, a transparent quartz, or a transparent quartz formed with an oxide layer. In addition, the material of the insulating substrate 110 may also be a plastic or resin material such as a PET film.

In the fourth step of the embodiment of the technical solution, the carbon nanotube film can be directly adhered to the surface of the insulating substrate 110 by its own adhesiveness.

In addition, the above-described carbon nanotube layer 140 adhered to the insulating substrate 110 may be treated with an organic solvent. Specifically, the organic solvent may be dropped on the surface of the carbon nanotube layer 140 by a test tube to infiltrate the entire carbon nanotube layer 140. The organic solvent may be the same as the organic solvent described in the second step, specifically a volatile organic solvent such as ethanol, methanol, acetone, dichloroethane or chloroform, and ethanol is used in this embodiment. After the carbon nanotube layer 140 is subjected to an organic solvent infiltration treatment, the carbon nanotube layer 140 can be attached to the surface of the insulating substrate 110 under the action of the surface tension of the volatile organic solvent, and the surface volume ratio is reduced, and the viscosity is reduced. Reduced properties, good mechanical strength and toughness. Alternatively, the carbon nanotube layer 140 may be better bonded to the insulating substrate 110 by a bonding agent.

Step 5: forming a source 151 and a drain 152 at intervals, and electrically connecting the source 151 and the drain 152 to the carbon nanotube layer 140.

The material of the source 151 and the drain 152 should have good electrical conductivity. Specifically, the material of the source 151 and the drain 152 may be metal, alloy, indium tin oxide (ITO), antimony tin oxide (ATO), conductive silver paste, and conductive Conductive materials such as electropolymers and metallic carbon nanotubes. The source 151 and the drain 152 may be formed by different methods depending on the type of material forming the source 151 and the drain 152. Specifically, when the material of the source 151 and the drain 152 is metal, alloy, ITO or ATO, the source 151 and the drain 152 may be formed by sputtering, sputtering, deposition, masking, etching, or the like. When the material of the source 151 and the drain 152 is a conductive silver paste, a conductive polymer or a metallic carbon nanotube, the conductive silver paste or the metallic nano carbon can be printed or directly adhered. The tube is coated or adhered to the surface of the insulating substrate 110 or the carbon nanotube layer 140 to form a source 151 and a drain 152. Generally, the source 151 and the drain 152 have a thickness of 0.5 nm to 100 μm, and the distance between the source 151 and the drain 152 is 1 to 100 μm.

In this embodiment, the source 151 and the drain 152 are made of metal. Step 5 above can be specifically performed in two ways. The first method specifically includes the following steps: first, uniformly coating a layer of photoresist on the surface of the carbon nanotube layer 140; secondly, forming a source 151 and a drain on the photoresist by photolithography such as exposure and development. In the region 152, the carbon nanotube layer 140 is exposed in the source 151 and the drain 152; again, in the above photoresist or source 151 by a deposition method such as vacuum sputtering, magnetron sputtering or electron beam evaporation deposition. And depositing a metal layer on the surface of the drain 152 region, preferably a palladium, titanium or nickel metal layer; finally, removing the photoresist and the metal layer thereon by an organic solvent such as acetone, thereby forming on the carbon nanotube layer 140 Source 151 and drain 152. The second method specifically includes the following steps: first, depositing a metal layer on the surface of the carbon nanotube layer 140; secondly, coating a surface of the metal layer with a photoresist; again, removing the source by photolithography such as exposure and development a photoresist outside the region of the pole 151 and the region of the drain 152; finally, the metal layer outside the source 151 region and the drain 152 region is removed by plasma etching or the like, and the source 151 region is removed by an organic solvent such as acetone and The photoresist on the drain 152 region, that is, the source 151 and the drain 152 formed on the carbon nanotube layer 140 are obtained. In this embodiment, the source 151 and the drain 152 have a thickness of 1 micron, and the distance between the source 151 and the drain 152 is 50 micrometers.

It can be understood that, in order to obtain the carbon nanotube layer 140 having better semiconductivity, after forming the source electrode 151 and the drain electrode 152, a metal carbon nanotube in the carbon nanotube layer 140 may be further removed. step. Specifically, the method includes the following steps: first, providing an external power supply, and secondly, connecting the positive and negative poles of the external power source to the source 151 and the drain 152; finally, applying a voltage across the source 151 and the drain 152 through the external power source, so that The metallic carbon nanotubes are heated and ablated to obtain a semiconducting carbon nanotube layer 140. This voltage is in the range of 1 to 1000 volts.

In addition, the above method of removing the metallic carbon nanotubes in the carbon nanotube layer 140 may also be performed by using a hydrogen plasma, microwave, terahertz (THz), infrared (IR), ultraviolet (UV) or visible (Vis) irradiation. The carbon nanotube layer 140 heats and ablates the metallic carbon nanotube to obtain a semiconducting carbon nanotube layer 140.

It can be understood that step 5 can also be performed before step four.

Step 6: forming an insulating layer 130 on the carbon nanotube layer 140.

The material of the insulating layer 130 may be a hard material such as tantalum nitride or tantalum oxide or a flexible material such as benzocyclobutene (BCB), polyester or acrylic resin. Depending on the type of material of the insulating layer 130, different methods can be used to form the Insulation layer 130. Specifically, when the material of the insulating layer 130 is tantalum nitride or tantalum oxide, the insulating layer 130 may be formed by a deposition method. When the material of the insulating layer 130 is benzocyclobutene (BCB), polyester or acrylic resin, the insulating layer 130 can be formed by a printing coating method. Generally, the insulating layer 130 has a thickness of 0.5 nm to 100 μm.

In the present embodiment, a tantalum nitride insulating layer 130 is formed by a deposition method such as plasma chemical vapor deposition to cover the surface of the carbon nanotube layer 140 and the source 151 and the drain 152 formed on the carbon nanotube layer 140. . The insulating layer 130 has a thickness of about 1 micrometer.

It can be understood that, depending on the different applications of the thin film transistor 10, a portion of the source 151 and the drain 152 may be exposed outside the insulating layer 130 by photolithography or etching similar to the formation of the source 151 and the drain 152.

Step 7: forming a gate 120 on the surface of the insulating layer 130 to obtain a thin film transistor 10.

The material of the gate 120 should have good electrical conductivity. Specifically, the material of the gate 120 may be a conductive material such as a metal, an alloy, an ITO, an ATO, a conductive silver paste, a conductive polymer, or a carbon nanotube film. The metal or alloy material can be aluminum, copper, tungsten, molybdenum, gold, or alloys thereof. Specifically, when the material of the gate 120 is metal, alloy, ITO or ATO, the gate 120 may be formed by sputtering, sputtering, deposition, masking, etching, or the like. When the material of the gate 120 is a conductive silver paste, a conductive polymer or a carbon nanotube film, the gate 120 can be formed by direct adhesion or printing. Generally, the gate 120 has a thickness of 0.5 nm to 100 μm.

In the embodiment of the present technical solution, a conductive film is formed as the gate 120 at a position on the surface of the insulating layer 130 and opposite to the semiconductor layer by a method similar to the formation of the source electrode 151 and the drain electrode 152. The gate 120 is electrically insulated from the semiconductor layer by the insulating layer 130. In the embodiment of the technical solution, the material of the gate 120 is aluminum, and the thickness of the gate 120 is about 1 micrometer.

Referring to FIG. 4 and FIG. 5, the second embodiment of the present invention provides a method for preparing the bottom gate type thin film transistor 20, which is basically the same as the method for preparing the thin film transistor 10 in the first embodiment. The main difference is that the thin film transistor 20 formed in this embodiment is a bottom gate type structure. The method for preparing the thin film transistor 20 of the second embodiment of the present technical solution includes the following steps:

Step 1: Prepare a carbon nanotube raw material.

Step 2: adding the above carbon nanotube raw material to a solvent and performing a flocculation treatment to obtain a nano carbon tube floc structure.

Step 3: separating the above-mentioned carbon nanotube floc structure from a solvent, and shaping the carbon nanotube floc structure to obtain a carbon nanotube film.

Step 4: Provide an insulating substrate 210.

Step 5: Form a gate 220 on the surface of the insulating substrate 210.

Step 6: Form an insulating layer 230 to cover the gate 220.

Step 7: Laying the above-mentioned carbon nanotube film on the surface of the insulating layer 230 to form a carbon nanotube layer 240.

Step 8: forming a source 251 and a drain 252 at intervals, and electrically connecting the source 251 and the drain 252 to the carbon nanotube layer 240.

The above-mentioned carbon nanotube film is adhered to the surface of the insulating layer 230 to be electrically insulated from the gate 220 and opposed to the gate 220. The source electrode 251 and the drain electrode 252 are formed directly on the surface of the carbon nanotube layer 240.

It can be understood that the above step 8 can be performed in the seventh step, that is, after the source electrode 251 and the drain electrode 252 are formed on the surface of the insulating layer 230, the carbon nanotube film is laid on the surface of the insulating layer 230 and covers the source electrode 251 and the drain electrode. 252.

Referring to FIG. 6, a third embodiment of the present technical solution provides a method for preparing a thin film transistor, which is basically the same as the method for preparing the thin film transistor 10 of the first embodiment. The main difference is that this embodiment forms a plurality of thin film transistors on the same insulating substrate to form a thin film transistor array. The method for preparing the thin film transistor of the embodiment specifically includes the following steps:

Step 1: Prepare a carbon nanotube raw material.

Step 2: adding the above carbon nanotube raw material to a solvent and performing a flocculation treatment to obtain a nano carbon tube floc structure.

Step 3: separating the above-mentioned carbon nanotube floc structure from a solvent, and shaping the carbon nanotube floc structure to obtain a carbon nanotube film.

Step 4: laying the at least one carbon nanotube film on the surface of an insulating substrate, patterning the carbon nanotube film to form a plurality of carbon nanotube layers.

The plurality of carbon nanotube layers may be formed at specific positions on the surface of the insulating substrate as needed. When applied to a liquid crystal display, a plurality of carbon nanotube layers may be formed on the surface of the insulating substrate in a row and in a row. Specifically, the step 4 further includes the following steps: (a) thinning the carbon nanotubes The film is adhered to the surface of the above insulating substrate. (b) The carbon nanotube film is cut by laser etching or plasma etching to form a plurality of carbon nanotube layers on the surface of the insulating substrate.

Step 5: forming a plurality of sources and a plurality of drains at intervals, and electrically connecting each of the carbon nanotube layers to a source and a drain.

Similar to the method of forming the source electrode 151 and the drain electrode 152 in the thin film transistor 10 of the first embodiment, in this embodiment, a metal film may be deposited on the surface of the entire insulating substrate on which the plurality of carbon nanotube layers are formed, and then etched. The metal film is patterned by a method such that a plurality of sources and a plurality of drains are formed at a predetermined position. The material of the source and the drain may also be an ITO film, an ATO film, a conductive polymer film, a conductive silver paste or a carbon nanotube film.

Step 6: Cover a plurality of insulating layers on the surface of each carbon nanotube layer. Similar to the method for preparing the insulating layer in the thin film transistor 10 of the first embodiment, a tantalum nitride film may be deposited on the surface of the entire insulating substrate, and then the tantalum nitride film is patterned by etching or the like, thereby being predetermined. A plurality of insulating layers are formed at a position last time. The material of the insulating layer may be a hard material such as cerium oxide or a flexible material such as benzocyclobutene (BCB), polyester or acrylic resin.

Step 7: forming a plurality of gates on the surface of each of the insulating layers to obtain a thin film transistor array including a plurality of thin film transistors. It should be understood by those skilled in the art that the step of cutting the carbon nanotube film by laser etching or plasma etching in the above step 4 may also be performed in any of steps 5 to 7.

A fourth embodiment of the present technical solution provides a thin film transistor array The method of the column specifically includes the following steps:

Step 1: Prepare a carbon nanotube raw material.

Step 2: adding the above carbon nanotube raw material to a solvent and performing a flocculation treatment to obtain a nano carbon tube floc structure.

Step 3: separating the above-mentioned carbon nanotube floc structure from a solvent, and shaping the carbon nanotube floc structure to obtain a carbon nanotube film.

Step 4: Provide an insulating substrate.

Step 5: forming a plurality of gates on the surface of the insulating substrate.

Step 6: forming at least one insulating layer covering the plurality of gates.

Step 7: laying the carbon nanotube film on the surface of the insulating layer, patterning the carbon nanotube film to form a plurality of carbon nanotube layers, and the plurality of carbon nanotube layers and the plurality of gates pass through the insulating layer Relative and insulated settings.

Step 8: forming a plurality of sources and a plurality of drains at intervals, and electrically connecting each of the carbon nanotube layers to a source and a drain.

The method for preparing a thin film transistor and a thin film transistor array provided by the embodiments of the present technical solution has the following advantages: First, the carbon nanotube film can be obtained as a semiconductor layer by the flocculation treatment without additional dispersing processing steps. The preparation process is simplified, thereby reducing the production cost of the thin film transistor and the thin film transistor array. Secondly, the carbon nanotube film obtained after the flocculation treatment has a certain viscosity, and therefore, the carbon nanotube film can be placed at a desired position by a direct adhesion method, which is simple and low in cost, and therefore, The preparation method of the thin film transistor provided by the technical solution has the advantages of low cost, environmental protection and energy saving. Third, the nano carbon The carbon nanotubes in the tube layer are entangled and evenly distributed. Therefore, when the carbon nanotube layer is used as a semiconductor layer, the carrier and the drain have a high carrier mobility and good mechanical properties. .

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by persons skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

10,20‧‧‧film transistor

110,210‧‧‧Insulation base

120,220‧‧‧ gate

130,230‧‧‧Insulation

140,240‧‧・nano carbon tube layer

151,251‧‧‧ source

152,252‧‧‧汲polar

1 is a flow chart of a method for preparing a thin film transistor according to a first embodiment of the present technical solution.

2 is a flow chart showing a process for preparing a thin film transistor according to a first embodiment of the present technical solution.

3 is a scanning electron micrograph of a carbon nanotube film in a thin film transistor according to a first embodiment of the present technology.

4 is a flow chart of a method for preparing a thin film transistor according to a second embodiment of the present technology.

FIG. 5 is a flow chart showing a process for preparing a thin film transistor according to a second embodiment of the present technology.

FIG. 6 is a flow chart of a method for preparing a thin film transistor according to a third embodiment of the present technology.

Claims (15)

A method for preparing a thin film transistor, comprising the steps of: preparing a carbon nanotube raw material; adding the above carbon nanotube raw material to a solvent and performing a flocculation treatment to obtain a nano carbon tube floc structure; The carbon tube floc structure is separated from the solvent, and the carbon nanotube floc structure is shaped to obtain a carbon nanotube film, which is composed of a plurality of unfunctionalized carbon nanotubes Forming; laying the above carbon nanotube film on the surface of an insulating substrate to form a carbon nanotube layer; forming a source and a drain at intervals, and electrically connecting the source and the drain to the carbon nanotube layer Forming an insulating layer on the surface of the carbon nanotube layer; and forming a gate on the surface of the insulating layer to obtain a thin film transistor. The method for preparing a thin film transistor according to claim 1, wherein the method for preparing the carbon nanotube raw material comprises the steps of: providing a carbon nanotube array formed on a substrate; and using a blade to The carbon nanotube array is scraped off from the substrate to obtain the carbon nanotube raw material. The method for producing a thin film transistor according to the above aspect of the invention, wherein the method of the flocculation treatment comprises ultrasonic dispersion treatment or high-strength stirring. The method for preparing a thin film transistor according to the above aspect of the invention, wherein the method for separating a carbon nanotube floc structure comprises the following steps: pouring the solvent containing the carbon nanotube floc structure Put into a funnel with filter paper; let stand for a while to obtain a separate carbon nanotube Floc structure. The method for preparing a thin film transistor according to claim 1, wherein the method for shaping the carbon nanotube floc structure comprises the following steps: the carbon nanotube floc structure is in a predetermined shape. Spreading; applying a certain pressure to the expanded carbon nanotube floc structure; and drying the solvent remaining in the carbon nanotube floc structure or naturally evaporating the solvent to obtain a carbon nanotube film. The method for preparing a thin film transistor according to the first aspect of the invention, wherein the separating and styling treatment comprises the steps of: providing a microporous membrane and an extraction funnel; and containing the nanocarbon The solvent of the tube floc structure is poured into the suction funnel through the microporous membrane; and a thin carbon nanotube film is obtained by suction filtration and drying. The method for preparing a thin film transistor according to claim 1, wherein the step of laying the carbon nanotube film on the surface of the insulating substrate further comprises the step of treating the carbon nanotube film with an organic solvent. The method for preparing a thin film transistor according to the first aspect of the invention, wherein after the carbon nanotube film is laid on the surface of the insulating substrate, further comprising removing the metallic carbon nanotube in the carbon nanotube film. step. The method for producing a thin film transistor according to the eighth aspect of the invention, wherein the step of removing the metallic carbon nanotube in the carbon nanotube film is performed after forming the source and the drain, Specifically, the method comprises: providing an external power source; connecting the positive and negative poles of the external power source to the source and the drain; and applying a voltage of 1 to 1000 volts at the source and the drain by an external power source to cause the metallic carbon nanotube to heat up And ablation to obtain a semiconducting carbon nanotube layer . The method for preparing a thin film transistor according to claim 8, wherein the step of removing the metallic carbon nanotube in the carbon nanotube layer is through a hydrogen plasma, microwave, terahertz, infrared The carbon nanotube layer is irradiated with ultraviolet light or visible light, and the conductive carbon nanotube is ablated. The method for preparing a thin film transistor according to claim 1, wherein after forming the insulating layer, further comprising the step of exposing the source and the drain portions to the outside of the insulating layer by photolithography or etching. The method for preparing a thin film transistor according to claim 1, wherein the gate, source and drain materials are metal, alloy, indium tin oxide, antimony tin oxide, conductive silver paste, and conductive Polymer or metallic carbon nanotubes. A method for preparing a thin film transistor comprises the steps of: preparing a carbon nanotube raw material; adding the above carbon nanotube raw material to a solvent and performing a flocculation treatment to obtain a nano carbon tube floc structure; The carbon tube floc structure is separated from the solvent, and the carbon nanotube floc structure is shaped to obtain a carbon nanotube film, and the carbon nanotube film is composed of a plurality of unfunctionalized carbon nanotubes. Providing an insulating substrate; forming a gate on the surface of the insulating substrate; forming an insulating layer covering the gate; laying the carbon nanotube film on the surface of the insulating layer to form a carbon nanotube layer; a source and a drain, and electrically connecting the source and the drain to the carbon nanotube layer. A method for preparing a thin film transistor comprises the steps of: preparing a carbon nanotube raw material; adding the above carbon nanotube raw material to a solvent and performing a flocculation treatment to obtain a nano carbon tube floc structure; The carbon tube floc structure is separated from the solvent, and the carbon nanotube floc structure is shaped to obtain a carbon nanotube film, and the carbon nanotube film is composed of a plurality of unfunctionalized carbon nanotubes. Laying the above-mentioned carbon nanotube film on the surface of an insulating substrate, patterning the carbon nanotube film to form a plurality of carbon nanotube layers; forming a plurality of sources and a plurality of drains at intervals, and making each of the above The carbon nanotube layers are electrically connected to a source and a drain; covering a plurality of insulating layers on the surface of each of the carbon nanotube layers; and forming a plurality of gates on the surface of each of the insulating layers to obtain a plurality of thin films Transistor. The method for preparing a thin film transistor according to claim 14, wherein the step of patterning the carbon nanotube layer is to cut the carbon nanotube film by laser etching or plasma etching, thereby A plurality of carbon nanotube layers are formed.