JP2004103719A - Organic semiconductor element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic semiconductor element in which the potential of an organic semiconductor film can be regulated and the variations in the threshold level can be prevented. <P>SOLUTION: Independently of the gate electrode, source electrode and drain electrode, the organic semiconductor element has an electrode for imparting the potential of an organic semiconductor film externally. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an organic semiconductor element, and more particularly to an organic semiconductor element having an organic semiconductor material and having an organic semiconductor transistor element.
[0002]
[Prior art]
2. Description of the Related Art In recent years, electronic devices using organic semiconductor materials have been widely developed, and development of organic EL (Electro-Luminescence), organic TFT (Thin Film Transistor), organic semiconductor laser, and the like, which are light emitting elements, has been reported. I have. Among them, an organic TFT, which is a kind of an organic semiconductor transistor, is regarded as a promising technology for forming an integrated circuit on a glass or plastic substrate at low cost.
[0003]
With respect to the structure of the organic TFT, Japanese Patent Application Laid-Open Nos. 08-228034, 09-232589, and 10-270712 disclose elements having a source and drain electrodes, a gate insulating film, and a gate electrode. .
[0004]
Originally, TFTs are often used for matrix display devices and the like, and are mainly used to maintain a constant source potential.
[0005]
[Problems to be solved by the invention]
It is considered that a TFT using an organic semiconductor operates stably when used to keep the source potential constant. On the other hand, when a logic circuit including an organic semiconductor is formed, transistors are often connected in series because of the logic circuit, and both the source potential and the drain potential may fluctuate dynamically. In this case, the potential of the organic semiconductor is estimated. The inventor has noticed that it is difficult to do so, and that this will hinder the design. Also, analog circuits have fluctuations in the threshold voltage. For example, in a differential amplifier, not only the source and drain of the transistor are not fixed to the power supply voltage or the ground voltage, but also fluctuations in the threshold voltage pose a serious problem. The inventor has noticed.
[0006]
The present invention is intended to solve the problem that, when an organic semiconductor TFT is used in a logic circuit or the like in which both the source potential and the drain potential dynamically fluctuate, it is difficult to estimate the potential of the organic semiconductor and hinder the design. is there. Therefore, an object of the present invention is to provide an organic semiconductor element capable of adjusting the potential of an organic semiconductor film and preventing a change in a threshold value, and for example, to provide an organic semiconductor element applicable to a logic circuit or the like. Another object of the present invention is to provide an organic semiconductor element having a simple structure and easy production, or an organic semiconductor TFT (transistor) element that is easy to design.
[0007]
[Means for Solving the Problems]
Therefore, the present invention provides an organic semiconductor element having a gate electrode, a gate insulating film, a source electrode, a drain electrode, and an organic semiconductor film on a substrate, further comprising an electrode for externally applying a potential of the organic semiconductor film. An organic semiconductor device is provided.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0009]
FIG. 1 is a diagram schematically illustrating a configuration of an organic semiconductor element having an organic semiconductor transistor element on a substrate, which is an example of the organic semiconductor element according to the present embodiment.
[0010]
Reference numeral 1 denotes a substrate, 2 denotes a contact for contacting wiring, 3 denotes a back wiring, 4 denotes a gate electrode, 5 denotes a gate insulating film, 6 denotes a drain electrode, 7 denotes a source electrode, and 8 denotes an organic semiconductor film. A semiconductor layer, 9 is an electrode for externally applying the potential of the organic semiconductor film, 10 is a surface protection layer as a surface protection film, and 11 is a back surface protection layer as a back surface protection film. An electrode that applies the potential of the organic semiconductor film from the outside is hereinafter referred to as a body electrode for convenience.
[0011]
On the back surface of the substrate 1, a back wiring 3 is arranged, a contact 2 connecting the back wiring 3 and the front surface is provided, and a gate electrode 4 is further arranged. The substrate is an insulating material. Further, a gate insulating film 5 is provided on the surface of the gate electrode, and a source electrode 7 and a drain electrode 6 are arranged on the surface of the gate insulating film 5 so as to be separated from each other. An organic semiconductor layer 8 is formed while they are separated and on the ends of the electrodes, and a body electrode 9 for externally applying the potential of the organic semiconductor layer 8 is formed on the organic semiconductor layer 8. From these, it can be said that the organic semiconductor transistor element portion according to the present embodiment is configured on the substrate. The organic semiconductor element of the present invention is an element having an element such as an organic semiconductor transistor element having such an organic semiconductor film on a substrate.
[0012]
Further, the organic semiconductor element of the present embodiment further has a surface protection layer 10 on the front surface side of the substrate, and further has a back surface protection layer 11 on the back surface side. The surface protection layer 10 is provided on the substrate surface side so as to cover the organic semiconductor transistor element. The back surface protective layer 11 is provided so as to cover the back surface wiring 3 on the back surface side.
[0013]
A potential can be externally applied to the organic semiconductor layer 8 by the body electrode 9, and a potential difference from the gate electrode can be adjusted.
[0014]
As a result, it is possible to prevent the threshold from fluctuating.
[0015]
This body electrode 9 is more preferably provided at a position facing the gate electrode. Since the ON / OFF operation of the organic semiconductor transistor element is determined by the potential difference between the gate electrode and the organic semiconductor facing the gate electrode, an electrode for externally applying the potential of the organic semiconductor film is provided at a position facing the gate electrode. Thereby, the potential of the organic semiconductor layer can be determined more stably.
[0016]
By applying a voltage different from the gate voltage to the body electrode 9 and combining the gate voltage and the voltage applied to the body electrode, the drain current can be adjusted.
[0017]
Alternatively, a voltage having a sign different from the ground voltage or the power supply voltage may be constantly applied to the electrode that externally gives the potential of the organic semiconductor layer 8 during driving. By always applying a voltage having a sign different from the ground voltage or the power supply voltage during driving, an operation of controlling on / off or an operation of being always on can be realized.
[0018]
By using these techniques, an IC card or an IC tag using the organic semiconductor element can be realized.
[0019]
The method of manufacturing the organic semiconductor transistor device will be described with reference to FIGS. 2 to 6 are cross-sectional views of only the organic semiconductor transistor portion.
[0020]
As shown in FIG. 2, first, a gate electrode 4 and a back wiring 3 which are formed by applying a copper foil on a surface and a back surface of an insulating substrate 1 made of epoxy resin and processed by a photolithography process are formed. Next, a contact hole is formed by irradiating a carbon dioxide laser beam from the surface, and then the contact 2 is formed by filling the hole with copper plating.
[0021]
Next, as shown in FIG. 3, a gate insulating film 5 made of alumina is formed.
Next, as shown in FIG. 4, a source electrode 7 and a drain electrode 6 made of gold were formed by vacuum evaporation through a metal mask.
[0022]
Next, as shown in FIG. 5, an organic semiconductor layer 8 made of pentacene is formed by vacuum evaporation through a metal mask. At this time, the thickness of the organic semiconductor layer was 20 nm.
[0023]
Further, as shown in FIG. 5, a body electrode 8 made of gold was formed by vacuum evaporation through a metal mask.
[0024]
Further, as shown in FIG. 6, a front surface protection layer 10 and a back surface protection layer 11 made of epoxy resin are formed to complete the process.
[0025]
For comparison, an organic semiconductor transistor having no body electrode as shown in FIG. 7 was also manufactured.
[0026]
As a result of an experiment in which the gate voltage was varied between 0 V and −5 V and the drain voltage was varied between 0 V and −5 V, the organic semiconductor transistor that was continuously supplied with the body electrode voltage of 0 V was obtained. In the case of a semiconductor transistor, the change in gate threshold voltage was only ± 0.2 V, whereas in the case of an organic semiconductor transistor having no body electrode, a change of ± 1 V or more was observed.
[0027]
In this prototype organic semiconductor transistor, stable driving could be realized by applying a constant voltage to an electrode (body electrode 9) that externally supplies the potential of the organic semiconductor film.
[0028]
Further, by applying a voltage of 2 V to the body electrode 9 of the prototype device, the depletion type organic semiconductor transistor which is always ON can be driven.
[0029]
【The invention's effect】
According to the present invention, it is possible to provide an organic semiconductor in which a potential difference between a gate electrode and an organic semiconductor film can be adjusted by further including an electrode which externally gives a potential of the organic semiconductor film. In addition, such an organic semiconductor element can prevent a threshold change of the organic semiconductor film.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an organic semiconductor device according to an embodiment.
FIG. 2 is a fragmentary cross-sectional view showing the organic semiconductor transistor element during the manufacturing process of the organic semiconductor transistor element according to the embodiment.
FIG. 3 is a fragmentary cross-sectional view showing the organic semiconductor transistor element in the course of manufacturing the organic semiconductor transistor element according to the embodiment.
FIG. 4 is a fragmentary cross-sectional view showing the organic semiconductor transistor element in the process of manufacturing the organic semiconductor transistor element according to the embodiment.
FIG. 5
FIG. 3 is a cross-sectional view of a main part showing the organic semiconductor transistor element in the course of manufacturing the organic semiconductor transistor element according to the embodiment.
FIG. 6 is a fragmentary cross-sectional view showing the organic semiconductor transistor element in the process of manufacturing the organic semiconductor transistor element according to the embodiment.
FIG. 7 is a cross-sectional view of an organic semiconductor transistor element according to a comparative example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Substrate 2 Contact 3 Back wiring 4 Gate electrode 5 Gate insulating film 6 Drain electrode 7 Source electrode 8 Organic semiconductor layer 9 Body electrode 10 Surface protection layer 11 Back protection layer

Claims (5)

An organic semiconductor element having a gate electrode, a gate insulating film, a source electrode, a drain electrode, and an organic semiconductor film on a substrate, further including an electrode for externally applying a potential of the organic semiconductor film. Organic semiconductor device. 2. The organic semiconductor device according to claim 1, wherein an electrode for externally applying a potential of the organic semiconductor film is provided at a position facing the gate electrode. The method of driving an organic semiconductor device according to claim 1, wherein the electrode that externally applies the potential of the organic semiconductor film is an electrode that applies a voltage different from a gate voltage to the organic semiconductor film. 2. The organic semiconductor element according to claim 1, wherein the electrode that externally supplies the potential of the organic semiconductor film is an electrode that constantly applies a voltage having a sign different from a ground voltage or a power supply voltage to the organic semiconductor film during driving. 3. Driving method. An IC card or an IC tag comprising the organic semiconductor element according to claim 1.

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