CN102263201A - A kind of organic field effect transistor and preparation method thereof - Google Patents

Abstract

The invention discloses an organic field effect transistor and a preparation method thereof, belonging to the field of organic electronics. The transistor comprises an insulating substrate, and a source electrode, a dielectric layer, a gate electrode, an organic semiconductor layer and a drain electrode which are arranged on the insulating substrate, wherein the source electrode is positioned on the insulating substrate and is in contact with the insulating substrate; the organic semiconductor layer is positioned in the center of the transistor, the upper end of the organic semiconductor layer is in contact with the drain electrode, and the lower end of the organic semiconductor layer is in contact with the source electrode; the grid electrode is two strip-shaped grid electrodes which are respectively positioned at two sides of the organic semiconductor layer; the dielectric layer is in a groove shape, the strip-shaped gate electrode is wrapped in the groove, and the dielectric layer isolates the gate electrode from the organic semiconductor layer, the source electrode and the drain electrode. The invention adopts low temperature process, improves the channel from the traditional plane type to the vertical type, controls the length of the channel of the transistor by controlling the thickness of the thin film of the organic semiconductor layer, greatly reduces the difficulty of preparing the short-channel organic transistor and reduces the preparation cost.

Description

A kind of organic field effect transistor and preparation method thereof

technical field

The invention belongs to the field of organic electronics, in particular to an organic field effect transistor and a preparation method thereof.

Background technique

With the continuous deepening of information technology, electronic products have entered every aspect of people's life and work; in daily life, people's demand for low-cost, flexible, low-weight, and portable electronic products is increasing; traditional inorganic semiconductor-based It is difficult for devices and circuits of materials to meet these requirements, so organic microelectronics technology based on organic polymer semiconductor materials that can realize these characteristics has received more and more attention under this trend.

Organic field effect transistors are the basic components of organic circuits, and their performance plays a decisive role in the performance of the circuit. Among them, the mobility determines the speed of the device's operation, which in turn affects the operating frequency of the circuit; the voltage, including the operating voltage and threshold voltage, determines the power consumption of the device and the circuit. Due to the explosive growth of information, people have always hoped that information processing technology will be faster and faster, and more and more content can be processed. There are many factors restricting the speed of information processing technology, including hardware and software. The operating frequency of a unit device is a fundamental issue in hardware. There are two main paths to increase the operating frequency of the device: one is to reduce the channel length, and the other is to increase the mobility of carriers. In the absence of major breakthroughs in current materials, the increase in carrier mobility is very limited, so the method to increase the operating frequency of the device is mainly to reduce the length of the channel. There are also many factors that restrict the capacity of information processing technology. In terms of hardware, it is mainly the degree of integration of circuits. To improve the degree of integration of circuits requires reducing the area of unit devices. Therefore, the existing organic field effect transistors have the defects of low device operating frequency and low circuit integration.

Contents of the invention

The technical problem to be solved by the invention is to provide an organic field effect transistor which can improve the working frequency of the device and the degree of circuit integration.

Another object of the present invention is to provide a method for preparing an organic field effect transistor.

In order to achieve the above object, the technical scheme adopted in the present invention is:

An organic field effect transistor, comprising an insulating substrate and a source electrode, a dielectric layer, a gate electrode, an organic semiconductor layer and a drain electrode on the insulating substrate, the source electrode is located on the insulating substrate, and The insulating substrate is in contact; the organic semiconductor layer is located in the center of the transistor, the upper end of the organic semiconductor layer is in contact with the drain electrode, and the lower end is in contact with the source electrode; the gate electrode is two strip-shaped The gate electrodes are respectively located on both sides of the organic semiconductor layer; the dielectric layer is groove-shaped, symmetrically distributed on both sides of the organic semiconductor layer, and the strip-shaped gate electrodes are wrapped in the grooves. The dielectric layer isolates the gate electrode from the organic semiconductor layer, source electrode, and drain electrode.

In the above solution, both the source electrode and the drain electrode are planar metal electrodes.

In the above solution, the insulating substrate is a silicon wafer, an insulating glass or an insulating plastic film with a silicon oxide or silicon nitride insulating film.

In the above solution, the material of the medium layer is an inorganic material or an organic material.

In the above solution, the material of the organic semiconductor layer is pentacene, copper phthalocyanine, P3HT, thiophene or rubrene.

In the above solution, the material of the gate electrode is a metal conductive material or a conductive organic material.

In the above solution, the material of the source electrode and the drain electrode is a high common function metal material or a conductive organic substance.

A method for preparing an organic field effect transistor, the method comprising:

(1) Prepare a planar source electrode on an insulating substrate;

(2) depositing a dielectric layer on the source electrode layer;

(3) preparing a strip-shaped gate electrode on the dielectric layer;

(4) Depositing a dielectric layer on the sidewall and top of the gate electrode, and removing excess dielectric layer on the surface of the bottom source electrode;

(5) Deposit an organic semiconductor layer in the center of the transistor;

(6) Prepare a planar drain electrode on the dielectric layer and the organic semiconductor layer.

In the above solution, in the step (1), the specific method for preparing the planar source electrode is: vacuum thermophysical deposition, electron beam deposition or sputtering metal electrode; or inkjet printing or spin coating organic electrode.

In the above scheme, in the step (2), the specific method for preparing the dielectric layer is: using low-pressure chemical vapor deposition, sputtering or atomic layer deposition to prepare the inorganic dielectric layer; or, using spin coating or inkjet printing method An organic dielectric layer is deposited.

In the above scheme, in the step (3), the specific method of preparing the gate electrode is: using photolithography technology to define its corresponding resist pattern, and then depositing metal by electron beam evaporation, sputtering or thermal evaporation, Finally, the pattern is transferred by metal lift-off method, so as to prepare the metal grid electrode; or, the inkjet printing technology is used to deposit and pattern the organic grid electrode.

In the above scheme, in the step (4), the specific method for preparing the dielectric layer is: the inorganic dielectric layer is deposited by low-pressure chemical vapor deposition, sputtering or atomic layer deposition, so that it has good step coverage , so that it can adhere to the sidewall of the gate electrode, and then remove the excess dielectric material on the surface of the source electrode by photolithography and anisotropic dry etching, so as to obtain a groove-shaped dielectric layer; the organic dielectric layer is obtained by spin-coating technology To deposit a dielectric film, after annealing treatment, define the pattern by photolithography technology, and finally remove the excess dielectric material on the surface of the drain electrode by etching technology, so as to obtain a groove-shaped dielectric layer.

In the above scheme, in the step (5), the specific method for preparing the organic semiconductor layer is: the organic semiconductor layer is prepared by a slow spin-coating technique so that it has good step coverage; and then through each Anisotropic dry etching removes the organic semiconductor material other than the sidewalls to form a patterned active layer.

In the above scheme, in the step (6), the specific method of preparing the planar drain electrode is: firstly, the gate electrode and the dielectric layer are protected by photolithography, and then vacuum thermophysical deposition, electron beam deposition or sputtering Technology to deposit metal electrode films, or use inkjet printing or spin coating technology to deposit organic electrode films, and then remove the photoresist and excess electrode materials in the gate electrode area by stripping to complete the preparation of the entire transistor.

Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

The organic field effect transistor proposed by the present invention improves the channel from the traditional planar type to the vertical type, so as long as the film thickness of the organic semiconductor layer can be controlled to control the channel length of the transistor, avoiding the use of electrons with low efficiency. Beam lithography technology greatly reduces the difficulty of preparing short-channel organic transistors, thereby reducing the cost of preparation. The present invention adopts a strip-shaped gate electrode, so that the aspect ratio of the channel of the device can be adjusted at will, expanding its application range. At the same time, a double-channel structure is adopted to increase the current driving capability of the device. The invention can effectively reduce the occupied area of the device and improve the integration degree of the circuit.

The invention also provides a preparation method of an organic field effect transistor, which adopts a low-temperature process, does not cause damage to other organic functional films that have been prepared, is compatible with the existing silicon microprocessing technology, and can make full use of existing equipment. Reduce the cost of new device fabrication.

Description of drawings

Fig. 1 is the three-dimensional structure diagram of the organic field effect transistor provided by the embodiment of the present invention;

Fig. 2 is the sectional view of the organic field effect transistor that the embodiment of the present invention provides;

Fig. 3 is the flow chart of the preparation organic field effect transistor provided by the embodiment of the present invention;

3-1 is a schematic diagram of preparing a planar source electrode on an insulating substrate according to an embodiment of the present invention;

3-2 is a schematic diagram of depositing a dielectric layer on the source electrode layer according to an embodiment of the present invention;

3-3 is a schematic diagram of preparing a strip-shaped gate electrode on a dielectric layer according to an embodiment of the present invention;

3-4 are schematic diagrams of depositing a dielectric layer on a gate electrode according to an embodiment of the present invention;

3-5 are schematic diagrams of depositing an organic semiconductor layer on a source electrode according to an embodiment of the present invention;

3-6 are schematic diagrams of preparing a planar drain electrode according to an embodiment of the present invention;

Fig. 4 is the process flow chart of the method for preparing organic field effect transistor in a specific embodiment of the present invention;

4-1 to 4-11 are structural schematic diagrams of the process of preparing an organic field effect transistor according to a specific embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

1 and 2, an embodiment of the present invention provides an organic field effect transistor, including an insulating substrate 101 and a planar source electrode 102 on the insulating substrate 101, a dielectric layer 103, a gate electrode 104, an organic semiconductor layer 105 and planar drain electrode 106; the planar source electrode 102 is located on the insulating substrate 101 and is in contact with the insulating substrate 101; the organic semiconductor layer 105 is located in the center of the transistor, the upper end of the organic semiconductor layer 105 is in contact with the planar drain electrode 106, and the lower end is in contact with the planar drain electrode 106; The source electrode 102 is in contact; the gate electrode 104 is two strip-shaped gate electrodes, which are respectively located on both sides of the organic semiconductor layer 105; the dielectric layer 103 is groove-shaped, symmetrically distributed on both sides of the organic semiconductor layer 105, and the The strip-shaped gate electrode 104 is wrapped in the groove, and the dielectric layer 103 separates the gate electrode 104 from the organic semiconductor layer 105 , the planar source electrode 102 , and the planar drain electrode 106 .

The insulating substrate is a silicon wafer with an insulating film such as silicon oxide or silicon nitride, insulating glass or insulating plastic film, etc.

When the material of the dielectric layer is an inorganic material, it can be inorganic materials such as silicon oxide, silicon nitride, zirconia, aluminum oxide, tantalum oxide or hafnium oxide; when the material of the dielectric layer is an organic material, it can be polyimide (PI ), polyvinylpyrrolidone (PVP), polymethylmethacrylate (PMMA) or organic materials such as parylene.

The material of the organic semiconductor layer is an organic semiconductor material such as pentacene, copper phthalocyanine (CuPc), P3HT, thiophene or rubrene.

The material of the gate electrode is a metallic conductive material such as gold, aluminum, platinum, copper or silver, or a conductive organic substance such as PEDOT:PSS.

The material of the source electrode and the drain electrode is a high common function metal material such as gold, platinum, silver, or a conductive organic substance such as PEDOT:PSS.

In the organic field effect transistor proposed in the embodiment of the present invention, the source electrode 102 and the drain electrode 106 are planar electrodes, which are respectively located at the bottom and top of the transistor, and are in contact with the organic semiconductor layer 105, so that the channel direction of the device changes from a horizontal direction to a vertical direction. , forming a vertical channel organic field effect transistor, so that the channel length of the transistor can be controlled only by controlling the film thickness of the organic semiconductor layer 105, avoiding the use of electron beam lithography technology with low efficiency, and greatly reducing the preparation time. The difficulty of channeling organic transistors, thereby reducing the cost of fabrication.

The embodiment of the present invention adopts the strip-shaped gate electrode 104, so that the aspect ratio of the device channel can be adjusted arbitrarily, and its application range is expanded; due to the use of double gate electrodes, the same organic semiconductor layer 105 and dielectric layer 103 Two interfaces are formed to further form a double-channel structure, which increases the current driving capability of the device. The embodiment of the invention can effectively reduce the occupied area of the device and improve the integration degree of the circuit.

Referring to Fig. 3 and Fig. 3-1 to Fig. 3-6, the embodiment of the present invention also provides a method for preparing an organic field effect transistor, which includes the following steps:

301. Prepare a planar source electrode on an insulating substrate, as shown in FIG. 3-1;

302. Deposit a dielectric layer on the source electrode layer to pattern it so as to isolate the gate electrode and the source electrode, as shown in FIG. 3-2;

303. Prepare a strip-shaped gate electrode on the dielectric layer described in step 302, as shown in FIG. 3-3;

304. Deposit a dielectric layer so that it adheres to the sidewall and top of the gate electrode, pattern it so as to isolate the gate electrode and drain electrode, and the organic semiconductor layer, and remove the excess dielectric layer on the surface of the bottom source electrode, as shown in Figure 3- 4 shown;

305. Deposit the organic semiconductor layer so that it is in the center of the entire transistor, as shown in FIG. 3-5;

306. Prepare a planar drain electrode to complete the fabrication of the transistor, as shown in FIG. 3-6.

A more optimal embodiment is described in detail below:

The organic field effect transistor provided in this embodiment includes: a thermally oxidized silicon insulating substrate 401, a planar Au source electrode 402, a strip-shaped Au metal gate electrode, a _SiO2 dielectric layer 406, a pentacene organic semiconductor layer 407, and a planar Au leakage electrode. Pole 408.

Refer to Fig. 4, Fig. 4 is the specific process flow chart of the preparation method of the organic field effect transistor provided in this embodiment; refer to Fig. 4-1 to Fig. 4-11, Fig. 4-1 to Fig. 4-11 are combined with Fig. 4 The production flow chart made by the process steps, the steps expressed are as follows:

501. Prepare a planar Au source electrode 402 on a SiO ₂ insulating substrate 401 grown by thermal oxidation, as shown in FIG. 4-1 ;

502. Prepare a SiO ₂ dielectric layer 403 on the source electrode layer by atomic layer deposition, as shown in FIG. 4-2;

503. Pattern the SiO ₂ dielectric layer 403 by photolithography plus etching technology, as shown in FIG. 4-3;

504. Prepare the glue pattern 404 of the strip-shaped gate electrode by photolithography technology, as shown in FIG. 4-4;

505. Electron beam evaporation deposits an Au thin film 405, as shown in FIG. 4-5;

506. Prepare an Au gate electrode by lift-off technology, as shown in FIG. 4-6;

507. Prepare a SiO ₂ dielectric layer 406 by atomic layer deposition technology, so that it wraps around the strip-shaped gate electrode, as shown in FIG. 4-7;

508. Remove the dielectric layer other than the strip-shaped gate electrode by photolithography plus etching technology, as shown in FIG. 4-8;

509. Deposit an organic semiconductor layer 407 on the source electrode 402, as shown in FIG. 4-9;

510. Removing the organic semiconductor outside the channel region by etching technology, as shown in FIG. 4-10;

511. Prepare a planar Au drain electrode 408 by electron beam evaporation, as shown in FIG. 4-11.

The preparation method of the organic field effect transistor provided by the embodiment of the present invention adopts a low-temperature process, which will not cause damage to other organic functional films that have been prepared, and is compatible with the existing silicon micromachining technology, and can make full use of existing equipment , to reduce the cost of new device fabrication.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (9)

1. organic field effect tube, comprise dielectric substrate and source electrode, dielectric layer, gate electrode, organic semiconductor layer and drain electrode on described dielectric substrate, it is characterized in that: described source electrode is positioned on the described dielectric substrate, and contacts with described dielectric substrate; Described organic semiconductor layer is positioned at described transistor central authorities, and described organic semiconductor layer upper end contacts with described drain electrode, and the lower end contacts with described source electrode; Described gate electrode is the gate electrode of two strips, lays respectively at the both sides of described organic semiconductor layer; Described dielectric layer is a grooved, is symmetrically distributed in the both sides of described organic semiconductor layer, and the gate electrode of described strip is wrapped in its groove, and described dielectric layer is kept apart described gate electrode and described organic semiconductor layer, source electrode, drain electrode.

2. organic field effect tube according to claim 1 is characterized in that: described source electrode and drain electrode are planar metal electrode.

3. organic field effect tube according to claim 1 is characterized in that: described dielectric substrate is long silicon chip, insulating glass or the ambroin film that silica or insulating silicon nitride film are arranged.

4. organic field effect tube according to claim 1 is characterized in that: the material of described dielectric layer is inorganic material or organic material.

5. organic field effect tube according to claim 1 is characterized in that: the material of described organic semiconductor layer is pentacene, CuPc, P3HT, thiophene or red glimmering rare.

6. organic field effect tube according to claim 1 is characterized in that: the material of described gate electrode is metallic conduction material or conductive organic matter.

7. organic field effect tube according to claim 1 is characterized in that: the material of described source electrode and drain electrode is that high official letter is counted metal material or conductive organic matter.

8. the preparation method of an organic field effect tube, it is characterized in that: described method comprises:

(1) the source electrode on preparation plane on dielectric substrate;

(2) metallization medium layer on described source electrode layer;

(3) gate electrode of preparation strip on described dielectric layer;

(4), and remove the unnecessary dielectric layer of bottom source electrode surface in the sidewall and the top metallization medium layer of described gate electrode;

(5) at transistor central authorities deposition organic semiconductor layer;

(6) drain electrode on preparation plane on dielectric layer and organic semiconductor layer.

9. the preparation method of organic field effect tube according to claim 8 is characterized in that:

In described step (1), the concrete grammar of the source electrode on preparation plane is: adopt the hot physical deposition of vacuum, electron beam deposition or splash-proofing sputtering metal electrode; Perhaps, adopt inkjet printing or spin coating organic substance electrode;

In described step (2), the concrete grammar of preparation dielectric layer is: adopt the method for low-pressure chemical vapor deposition, sputter or ald to prepare the inorganic medium layer; Perhaps, adopt spin coating or inkjet printing methods deposition organic dielectric layer;

In described step (3), the concrete grammar of preparation gate electrode is: adopt photoetching technique to define its corresponding glue pattern of carving, come plated metal by the method for electron beam evaporation, sputter or thermal evaporation again, come transition diagram by the method for metal-stripping at last, thereby prepare metal gate electrode; Perhaps, adopt inkjet technology to deposit and graphical organic gate electrode;

In described step (4), the concrete grammar of preparation dielectric layer is: the inorganic medium layer deposits by the method for low-pressure chemical vapor deposition, sputter or ald, make it have good step coverage, thereby can be attached on the gate electrode sidewall, then by photoetching and anisotropic dry etching material removal medium unnecessary on the electrode surface of source, thereby obtain the dielectric layer of groove shape; Organic dielectric layer comes the deposition medium film by spin coating technique, after the annealed processing again by photoetching technique definition figure, at last by lithographic technique material removal medium unnecessary on the drain electrode surface, thereby obtain the dielectric layer of groove shape;

In described step (5), the concrete grammar of preparation organic semiconductor layer is: organic semiconductive layer prepares film by spin coating technique at a slow speed, makes it have good step coverage; By anisotropic dry etching the organic semiconducting materials beyond the sidewall is removed then, formed patterned active layer;

In described step (6), the concrete grammar of the drain electrode on preparation plane is: at first by photoetching technique gate electrode and dielectric layer are protected, come the deposit metal electrodes film by the hot physical deposition of vacuum, electron beam deposition or sputtering technology then; Perhaps, adopt inkjet printing or spin coating technique to come the sedimentary organic material electrode film, remove the photoresist of gate electrode area and unnecessary electrode material by the method for peeling off then, finish the whole transistor preparation.

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