JPS58114465A - High molecular semiconductor field effect transistor and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain an FET being provided with flexibility, exellent moldability, low price and large area by employing high molecular semiconductor. CONSTITUTION:Stock gas is introduced onto an insulating substrate 11 made of plate glass, surface-oxidized Si wafer, high molecular film or the like, thereby forming, for example, a p type cis form polyacetylene polymer film 12, and a gate electrode 13 made of Al, In or Mg is attached, thereby forming a Schottky barrier. When an n type high molecular semiconductor is employed, the electrode 13 is formed of Pt or Au having large work function. A source electrode 14 and a drain electrode 15 should be ohmic in any case, its gate width is approx. 100mum-5mm., its gate length is 50mum-1mm., and the electrodes are disposed at one or both sides. The high molecular semiconductor can be formed on the large area, and when a flexible material is employed for the substrate and the electrode, a flexible element can be obtained, and an FET can be formed inexpensively as compared with an inorganic semiconductor material.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in field effect transistors.

Conventionally, field effect transistors have used inorganic semiconductors such as silicon and germanium as semiconductors. General view: Inorganic semiconductors are crystal pulling devices.

Its area is limited by the dimensions of the epitaxial fit, etc., and for example, in single crystal silicon, it is currently about 15 Cy.
Only a diameter of about a (6 inches f) can be produced.

Therefore, there is a drawback that a field effect transistor cannot be formed on a large-area substrate. Furthermore, since inorganic semiconductors inherently have characteristics such as flexibility, moldability, and low cost, conventional field effect transistors using them have also been subject to limitations in these respects.

The present invention improves these conventional drawbacks, and
The purpose is to use a polymer semiconductor as a semiconductor (2) to provide a field effect transistor with excellent flexibility, moldability, low cost, etc. (2), which can easily be made into a large area, and a method for manufacturing the same (2). There are two examples below, which will be explained in detail.

FIG. 1 is a cross-sectional view of a Schottky barrier gate field effect transistor according to an embodiment of the present invention, in which 11 is an insulating substrate, 12 is a polymer semiconductor film, and 16 is a gate electrode (gate film) forming a Schottky barrier. ), 14,
15 is a source electrode and a drain electrode having ohmic contact.

In this embodiment, a two-polymer semiconductor film 12 is formed by polymerization on an insulating substrate 11, two gate electrodes 15 are formed thereon, and a gate region directly below the gate electrode 15 is disposed on the polymer semiconductor film 12. Low source electrode 14 and drain electrode 15
was formed.

When a P-type polymer semiconductor is used as the polymer semiconductor 1[12, the gate electrode 13 is made of a material with a small work function, such as Al, If&
, My, etc. are used. In addition, if a cylindrical polymer semiconductor is used as the polymer semiconductor film 12, the gate electrode 1 should be made of a material with a large work function, such as Pt or Aμ.
3. Source electrode 14. The drain electrode 15 is P
In either case of the 2% type, a metal or a semiconductor with high conductivity that allows ohmic contact may be used. The insulating substrate 11 is plate glass.

Surface oxidized silicon wafers, polymer films, etc. can be used.

Generally, the longer the width of the C gate, the better, 100μ ~ 5xgt
On the other hand, the gate length, that is, the distance between the source and drain, is preferably as short as possible.
Two. The electrode arrangement in the figure can be a coplanar structure in which only one side of the polymer semiconductor film 12 is used, and a staggered structure in which both sides of the polymer semiconductor film 9 are used. A more specific example of this Schottky barrier gate field effect transistor will be described below.

Specific example 1 A glass substrate of 50 mm x 1 mm (thickness) was used as the insulating substrate 11, and a resist (2 AZ1550J (trade name)) was applied thereon, and this was patterned using a known photolithography method. Six resist patterns each having square holes of 1yxax1ms were created.

Next (:, on this patterned resist-dit-Daller catalyst (ononosoptoxytitanium and polyester: IF-
The ratio of AX/Ti = 4 is C2 (
Then mix with toluene to make a Ti base with a concentration of 100 m
After that, the substrate was placed in Ar gas at normal pressure and acetylene gas was sprayed onto the substrate at a rate of 5Qcc 1 min. As a result, a cis-type polyacetylene film having a thickness of 0.2 μm was polymerized and formed on the substrate. Of course, it is also possible to dope with a P-type dopant in order to further increase the C2 conductivity.

Next, the substrate was washed 5 times with toluene to remove the Tigutsu catalyst, and then the substrate was pressurized to about 1.5 to 2 atm with A degas. Atomized 1 from the nozzle of a spray container containing
Seven tons were sprayed onto two substrates. This acetone mist passed through the polymeric film and connected to the resist ζ, and the resist was peeled off from the substrate. At this time, the polymer film on the resist was also peeled off (4), so a pattern of the polymer film was formed on the substrate (lift-off 6). It should be noted that lift-off could not be achieved successfully by simply applying acetone or dipping it in acetone as usual.

Next, using resist, a door with a width of 6000 μm and a length of 5 μm was created.
A gate electrode was created. In this case, since polyacetylene is a P-type semiconductor, 6N aluminum was used for the gate electrode. Further, a source electrode 14 and a drain electrode 15 having a width of 3000 μm were formed using gold.

The transfer characteristics of the Schottky gate type polyacetylene field effect transistor manufactured in this way are shown in Figure 2.
was approximately 100μ, and the cutoff frequency f, which is one of the frequency characteristics, was 1KHz. Moreover, FIG. 3 is a line section showing an example of the output characteristics.

Specific Example 2 In this example, butatriene type polyamide and cetlene was used as the polymer semiconductor.

The secondary semiconductor film 12 is formed by forming a film of diacetylene monomer on the insulating substrate 11, and this ! = 180 Mrad/
A polydiacetylene film having a thickness of 0.1 μm was obtained by irradiating with gamma rays for 100 hours. Note that at this time, diacetylene monomer C, niiodine, etc. may be doped. Then, a Schottky barrier gate type polydiacetylene field effect transistor was manufactured using the same parameters as in Example 1.

As a result, ym is approximately 1.25 (drain voltage = 10
A field effect transistor was obtained in which m') and f were approximately 100 KHz.

FIG. 4 is a cross-sectional view of a MIS type field effect transistor having a C2 insulating film between the gate and the semiconductor, which is another embodiment of the present invention.
6 is a goo electrode, and 17 is an insulating film.

In this embodiment, a gate electrode 16 formed on an insulating substrate 11 is used.
An insulating film 17 is formed on the insulating film 17, and a ζ bipolymer semiconductor 1[i2 is polymerized and formed on the insulating film 17, and a source electrode 14 and a drain electrode 15 are formed on the polymer semiconductor film 12 with the gate region in between. This is what I did.

The gate electrode 16 may be made of any metal, but the source electrode 14 and drain electrode 15 are made of the polymer semiconductor film 1.
The material must be able to make ohmic contact with 2. As the insulating film 17, a plasma polymerized film, a pyrolytic vapor phase polymerized film (
For example, a parylene film (trade name), an inorganic oxide film, etc. can be used. The dimensions of the transistor, such as gate width and gate length, are the same as the Schottky pariah gate field effect transistor shown in FIG. The transistor structure can be a coplanar structure in which an electrode is formed on only one side of the polymer semiconductor film 12, or a staggered structure in which both sides are formed with two electrodes. Hereinafter, two more specific embodiments of this MIS field effect transistor will be explained.

Specific Example 6 A glass substrate was used as the insulating substrate 11, and aluminum was deposited thereon and then patterned to form a gate electrode 16 having a gate length of 1 μm and a gate width of 5000 μm.

Next, as the insulating film 17, a plasma polymerized film with a film thickness of 500 A containing organosylochitin as a monomer is used.
t (2 formed on the electrode 16. Formation of the gate electrode C2 using this plasma polymerized film is effective by using the above-mentioned pressurized spraying of resist solvent and lift-off method. Gate electrode 16C; pyrolysis gas The same applies to the case where a phase polymer film is used.

Next, C: on the insulating film 17: A Bo9 acetylene film having a thickness of 200 OA was formed as the polymer semiconductor film 12 by direct polymerization C2. In this case as well, it is effective to use the above-mentioned spray method and lift-off method. Then, on top of that, a source electrode 14 and a drain electrode 15 made of dimetallic metal were formed with a source-drain spacing of 1 μm.

The transfer characteristics of the MXS type polyacetylene field effect transistor manufactured in this way are shown in FIG. 5C.

When the drain voltage VD=10V, gTn and jS are 1-5m.
? ! ;, showed fr=10 KHz. Moreover, FIG. 6 (-- shows an example of its output characteristics.

Specific example 4 MIS using the same polydiacetylene used in black body example 2 as the polymer semiconductor film 12 and using the same transistor structure parameters as specific example 3 except that the film thickness was set to 0.2 μm.
A type polydiacetylene field effect transistor was fabricated.

As a result, the drain current decreased by 1°, but the drain voltage V, = i 0 V! The door became larger by 3 doors. Further, f was 15D KHz.

Specific example 5 Insulation w/X17 with a thickness of 500 mm formed by sputtering
When a MIS type field effect transistor with C2, which is the same as in Example 4 except that AI and Os of λ were used, the drain voltage Vn = 10 V and gm = j a23,
A transistor with fr = 70 KHz was obtained.

FIG. 7 shows the molecular structures of polymer semiconductors that can be used in the field effect transistor of the present invention, in which (1) is trans-type polyacetylene, (2) is cis-type polyacetylene, (3) is polypyrrole, (4) is polythenylene, (
5) is polyparaphenylene, (6) is polyparaphenylene vinyl:/, (7) is polyparaphenylene sulfide, (8) is polyparaphenylene oxide, (9) is acetylene type polydiacetylene, (1 is Butatriene-type polydiacetylenes are shown respectively.In general, linear conjugated polymers exhibit excellent semiconductor properties as polymer semiconductors. This figure shows the molecular structure of a polymer semiconductor.In addition to the above, the present invention can also use polymers that exhibit semiconducting properties.The polymer semiconductor can be constructed with a C chain extending in the current direction. This will improve the electrical characteristics.

Figure 6 &: The polymer semiconductor shown is an impurity (dopant)
Add (dope) helogne or Lewis acid as
By doping with an alkali metal or quaternary ammonium salt, a P-type semiconductor can be obtained. An increase in electrical conductivity was also observed.

Therefore, as described above, it can be used as a ζ2 semiconductor device in the same way as an inorganic semiconductor.

Note that the source electrode 14 and the drain electrode 15 in FIGS. 1 and 4C2 or the gate electrode 16 in FIG.
In addition to the above, (2) a polymer semiconductor may be doped with impurities by diffusing iodine, herogen, etc. by vapor phase diffusion, etc. to lower the resistance. Also, as the insulating substrate 11, a polymer semiconductor insulated by breaking the double bonds can be used.

As can be seen from the above explanation, the present invention (=) uses a polymer semiconductor as a semiconductor, so it has flexibility, moldability,
It is easy to create field effect transistors that are low cost and easy to increase in area (there is a double effect).

That is, in the case of polymer semiconductors, it is possible to use a method in which a catalyst is coated on a large-area substrate (two), and then raw material gas is introduced onto the substrate (two), so it is possible to use a crystal pulling device like inorganic semiconductors.
Not limited by equipment such as epitaxial growth equipmentζ
On a substrate with an area of 2 people (2 elements can be formed).

Furthermore, if a flexible substrate is used and a flexible material is used as the electrode, for example, a polymer semiconductor doped with impurities to increase its conductivity, the polymer semiconductor itself becomes flexible. This makes it possible to realize a flexible element. If such a flexible element is used, two elements can be formed on a curved surface, so if the entire board is rolled up, space can be used effectively and element density can be improved.

Furthermore, since a polymer semiconductor having a large area can be formed by batch molding, and a polymer semiconductor having a desired shape can be formed without using phosphorography technology, its moldability is improved.

Moreover, since the polymer material itself is low in price, when an inorganic semiconductor material is used, it is possible to provide an element that is low in cost. Furthermore, the maximum temperature during the manufacturing process is approximately 90° C. when prebaking the resist, which is optimal for low-temperature processes.

Therefore, it is extremely effective to apply the polymer semiconductor field effect transistor of the present invention to large-sized display driver devices, large-area integrated circuits integrated into two-curved structures, and the like.

In addition, @42, which forms a film using a polymer semiconductor of a polymer semiconductor field effect transistor by a lift-off method,
Lift-off can be easily achieved by spraying the resist solvent in a mist form (=spraying).

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a Schottky barrier gate field effect transistor according to an embodiment of the present invention, and Figures WI2 and 5 are lines showing examples of transfer characteristics and output characteristics of a Schottky barrier gate polyacetylene field effect transistor. The fourth factor is another embodiment of the present invention, which is a diagram showing an example of the transfer characteristics and output characteristics of the gate and semiconductor (= insulating film), and FIG. 7 is a field effect transistor of the present invention. 11 is a diagram showing the molecular structure of a polymer semiconductor that can be used for. 11 is an insulating substrate, 12 is a polymer semiconductor film, 13 is a gate electrode forming a Schottky barrier, 14 is a source electrode, 15 is a drain electrode, and 16 is a The gate electrode 17 is an insulating film. Fig. 1 Fig. 2 vo (volt) Fig. 40 Fig. 5 Fig. 611i5 VD (volt)

Claims (1)

[Scope of Claims] (1) A polymer semiconductor film having one conductivity type formed on an insulating substrate; a gate coating for generating a depletion layer by applying a voltage; Directly below the gate coating C
A polymer semiconductor field effect transistor comprising a source electrode and a drain electrode that are in ohmic contact with each other and are formed on the polymer semiconductor film with two gate regions interposed therebetween. (2. A polymer semiconductor field effect transistor according to claim 1, wherein the gate film is a metal electrode that forms a Schottky barrier junction with the polymer semiconductor film. Molecular semiconductor field effect transistor. (3) In the polymer semiconductor field effect transistor according to claim 1, the gate film is formed on the polymer semiconductor film (=on the formed insulating film and on the core insulating film). A polymer semiconductor field effect transistor comprising two metal electrodes. (4) A polymer semiconductor field effect transistor C according to claim 3; wherein the insulating film is a plasma polymerized film. or a polymer semiconductor field effect transistor comprising a pyrolytic vapor phase polymerized film. (5) A polymer semiconductor film having one conductivity type formed on an insulating substrate and a voltage applied to the polymer semiconductor film. A gate film for applying voltage to generate a depletion layer, and a source electrode and a drain electrode that make ohmic contact are formed directly under the gate film (the generated gate region is 8C) and on the polymer semiconductor film. In the method 62 for manufacturing a polymer semiconductor field effect transistor, a predetermined resist pattern is formed on the insulating substrate, and then a polymer semiconductor film is formed on the resist pattern by polymerization. Lift-off method 1: After spraying 17 tons of the polymer semiconductor film onto the surface thereof, a part of the polymer semiconductor film is peeled off along with the resist to form a predetermined pattern of the polymer semiconductor film. A method for manufacturing a polymer semiconductor field effect transistor, characterized in that: