JP2013076656A - Transparent biosensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent biosensor capable of accurately acquiring signal information of an organism-related substance when acquiring the signal information simultaneously with microscopic observation by using the biosensor including a TFT.SOLUTION: The transparent biosensor includes a transparent base material 1, and a transparent thin film transistor element part A and a transparent organism-related substance sensitive part B which are formed on the transparent base material 1 and is configured so that a gate electrode 2 included in the thin film transistor element part A has an ultraviolet protection function against an oxide semiconductor film 4 composing the thin film transistor element part A. The gate electrode 2 is configured so as to be any one of a transparent electrode (i) including an ultraviolet protection material, a transparent electrode (ii) composed of the ultraviolet protection material and a transparent electrode (iii) having a band gap smaller than a band gap of the oxide semiconductor film.

Description

  The present invention relates to a transparent biosensor, and more particularly, to a transparent biosensor that can accurately acquire signal information when acquiring signal information of a biological substance simultaneously with microscopic observation.

  Living organisms are composed of cells of the order of μm, and the cells are aggregates of nm-order structures such as proteins, lipids or nucleic acids. On the other hand, the fine processing of the semiconductor processing technology is also on the order of nm, which is about the same as the cell size. By applying elements fabricated using such semiconductor processing technology to biological nanostructures, it becomes possible to control the functional expression of cells and acquire biomolecular information such as proteins and nucleic acids, for example. Currently, it is being studied in various fields (Non-Patent Document 1).

  In particular, various methods for inspecting biologically related substances such as DNA, sugar chains or proteins have been developed for the purposes of disease diagnosis, detection of individual differences in drug metabolism, or food or environmental monitoring. Research on biosensors that acquire electrical signal information from (biomolecules) is advancing. In recent years, field effect transistors (FETs) have been used for biological purposes from the viewpoint of fast electrical signal conversion and easy connection between integrated circuits and MEMS (Micro Electro Mechanical System). Many studies have been conducted on biosensors that detect sensitive reactions.

  A biosensor using an FET has a structure in which a gate electrode is removed from a MOSFET and a sensitive film is deposited on an insulating film, and is called “ISFET (Ion Sensitive FET)”. And it can function as various biosensors by placing an oxidoreductase, various proteins, DNA, antigen or antibody on the sensitive membrane (Patent Documents 1 and 2). Specifically, an FET used in a biosensor has a source electrode, a drain electrode, and a gate insulating film formed on the surface of a silicon substrate, and a metal electrode on the surface of the gate insulating film between the source electrode and the drain electrode. ing. A DNA probe and alkanethiol are placed on the surface of the metal electrode.

  In recent years, research on thin film transistors (hereinafter also referred to as “TFTs”) using an oxide semiconductor film has been actively conducted. Patent Document 3 proposes an example in which a polycrystalline film of an oxide made of In, Ga, and Zn (abbreviated as “IGZO”) is used as a semiconductor film of a thin film transistor. In Non-Patent Document 2 and Patent Document 4, IGZO is proposed. An example in which the amorphous film is used as a semiconductor film of a thin film transistor has been proposed. Thin film transistors using these IGZO as semiconductor films can be formed at a low temperature at room temperature, and can be formed without causing thermal damage to a non-heat resistant substrate such as a plastic substrate. This IGZO-based oxide semiconductor is a transparent material having a high transmittance to visible light, and also has a good electrical property even when a conventionally known transparent conductive material such as ITO is used as a gate electrode, a source electrode, or a drain electrode. Since transparent contact characteristics can be obtained, a transparent thin film transistor using only a transparent material has been studied.

Ryo Matsumoto and Yuji Miyahara, `` Current status of biosensors and future issues '', Applied Physics, Vol. 80, No. 3, p.205-210 (2011). K. Nomura et.al., Nature, vol.432, p.488-492 (2004)

JP 2002-296228 A JP 2007-108160 A JP 2004-103957 A JP 2005-088726 A JP 2011-009293 A

  Biosensors using TFTs are being researched because microfabrication using semiconductor processing technology is possible. When a biosensor using a TFT detects the state of a biological substance such as a cell or DNA as electrical signal information, the obtained information data is an important evaluation factor. Microscopic observation of the state is also an important evaluation means. For microscopic observation of cells and the like, it is desirable to directly observe at high magnification with transmitted light. In order to obtain the electrical signal information from the biological substance on the sensitive membrane and to observe the state of the signal with a microscope, an inverted microscope that observes the biological substance from below the biosensor is preferably used. Therefore, in a biosensor having a TFT, it is preferable to use a transparent oxide semiconductor film as the semiconductor film.

  The use of an IGZO-based oxide semiconductor film, which is a transparent oxide semiconductor, can realize the transparency of the entire biosensor having TFTs. However, the oxide semiconductor itself can be converted into ultraviolet rays, particularly UV-C having a wavelength of 200 nm to 280 nm. It is known to respond to this (Patent Document 5). However, when such an oxide semiconductor film is applied to a transparent biosensor capable of obtaining electrical signal information and observing under a microscope, the transparent biosensor is irradiated with irradiation light from above or below under the microscope. Is done. Therefore, the output signal from the oxide semiconductor film may fluctuate or decrease due to ultraviolet rays included in the irradiation light. As a result, there is a possibility that the signal information of the biological substance acquired simultaneously with the microscopic observation is different from the signal information of the biological substance not acquired simultaneously with the microscopic observation.

  The present invention has been made in order to solve the above-mentioned problems, and the object of the present invention is to obtain signal information of a biologically relevant substance simultaneously with microscopic observation using a biosensor having a TFT. The object is to provide a transparent biosensor that can be obtained accurately.

  (1) A transparent biosensor according to the present invention includes a transparent base material, a transparent thin film transistor element portion provided on the transparent base material, and a transparent biological material sensitive part, and the thin film transistor element portion includes The gate electrode has an ultraviolet blocking function for the oxide semiconductor film constituting the thin film transistor element portion.

  According to the present invention, since the gate electrode of the transparent thin film transistor element portion has an ultraviolet cut function for the oxide semiconductor film, the ultraviolet light contained in the light irradiated from below or above the transparent biosensor is irradiated with the irradiated light. The gate electrode arranged on the side acts to cut off the ultraviolet rays. As a result, it is possible to prevent the oxide semiconductor film from being sensitive to ultraviolet rays and to prevent the output signal from the oxide semiconductor film from fluctuating or decreasing. Can be obtained accurately.

  (2) In the transparent biosensor according to the present invention, the gate electrode comprises (i) a transparent electrode containing an ultraviolet cut material, (ii) a transparent electrode made of an ultraviolet cut material, and (iii) the oxide semiconductor film. The transparent electrode has a band gap smaller than the band gap.

  According to this invention, since the gate electrode which is the ultraviolet ray cutting means is any one of the above (i) to (iii), the ultraviolet ray contained in the light emitted from below or above the transparent biosensor is irradiated with the ultraviolet ray. The gate electrode arranged on the light side acts to cut off the ultraviolet rays. In particular, a transparent electrode having a band gap smaller than that of an oxide semiconductor film is preferable because ultraviolet light that excites electrons in the oxide semiconductor film can be cut out of irradiated light.

  (3) In the transparent biosensor according to the present invention, the thin film transistor element portion has a bottom gate type thin film transistor structure or a top gate type thin film transistor structure.

  According to the present invention, any top gate type or bottom gate type thin film transistor structure can be preferably applied.

  (4) In the transparent biosensor according to the present invention, the thin film transistor element portion has a bottom gate type thin film transistor structure, and a detection electrode connected to the gate electrode via an insulating film is provided above the thin film transistor structure, The detection electrode has the ultraviolet blocking function for the oxide semiconductor film.

  According to the present invention, the detection electrode provided above the thin film transistor structure has the same ultraviolet ray blocking function as that of the gate electrode. Therefore, the ultraviolet rays that enter from both below and above the transparent biosensor are transmitted below the oxide semiconductor film. The gate electrode disposed above and the detection electrode disposed above act to cut.

  (5) In the transparent biosensor according to the present invention, the oxide semiconductor film is preferably an IGZO-based oxide semiconductor film.

  An oxide semiconductor film made of an IGZO-based oxide semiconductor material is sensitive to ultraviolet rays contained in light irradiated when a biological substance is observed with a microscope. According to the present invention, it is possible to prevent the output signal from the oxide semiconductor film from fluctuating or decreasing, and thus it is possible to accurately acquire the signal information of the biological substance obtained simultaneously with the microscopic observation.

  According to the transparent biosensor of the present invention, since the gate electrode disposed on the irradiation light side cuts the ultraviolet ray contained in the light irradiated from below or above the transparent biosensor, the oxide semiconductor film Can be prevented from being sensitive to ultraviolet rays, the output signal from the oxide semiconductor film can be prevented from fluctuating or decreasing, and the signal information of the biological substance acquired simultaneously with the microscopic observation can be acquired accurately. .

It is a schematic cross section which shows an example of the transparent biosensor which has the bottom gate type TFT which concerns on this invention. It is a schematic cross section which shows another example of the transparent biosensor which has the bottom gate type TFT which concerns on this invention. It is a schematic cross section which shows another example of the transparent biosensor which has a bottom gate type TFT which concerns on this invention. It is a schematic cross section which shows an example of the transparent biosensor which has a top gate type TFT which concerns on this invention. It is a schematic cross section which shows another example of the transparent biosensor which has a top gate type TFT which concerns on this invention.

  The transparent biosensor according to the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following forms within the range including the technical idea.

  As shown in FIGS. 1 to 5, the transparent biosensors 10 and 20 according to the present invention include a transparent substrate 1 and a transparent thin film transistor element A (hereinafter referred to as “TFT element A”) provided on the transparent substrate 1. And a transparent biological substance sensitive part B. The gate electrode 2 included in the TFT element portion A is characterized in that it has an ultraviolet cut function for the oxide semiconductor film 2 constituting the TFT element portion A.

  In the transparent biosensors 10 and 20, the gate electrode 2 included in the transparent TFT element portion A has an ultraviolet cut function with respect to the oxide semiconductor film 4. Therefore, light irradiated from below or above the transparent biosensors 10 and 20. The gate electrode 2 disposed on the irradiation light side acts to cut the ultraviolet rays contained in the ultraviolet rays. As a result, the oxide semiconductor film 4 can be prevented from being sensitive to ultraviolet rays, and the output signal from the oxide semiconductor film 4 can be prevented from fluctuating or decreasing. Information can be obtained accurately.

  Hereinafter, the configuration of the transparent biosensor will be described in detail by dividing it into one having a bottom gate type TFT and one having a top gate type TFT. In the present invention, “above” means that it is provided directly on itself, and when it is not provided directly, it is referred to as “above”. In addition, “covering” means that it is provided directly on itself and around it. Further, “cutting off ultraviolet rays” means absorbing or reflecting ultraviolet rays.

[Transparent biosensor with bottom-gate TFT]
The transparent biosensor 10 shown in FIGS. 1 to 3 includes a TFT element part A having a bottom gate type thin film transistor (hereinafter also referred to as “TFT”) and a biological substance sensitive part B.

  A transparent biosensor 10A having a bottom-gate TFT shown in FIG. 1 includes a transparent base material 1, a TFT element part A and a biological substance sensitive part B provided on the transparent base material 1. The TFT element part A and the biological substance-sensitive part B are provided side by side without overlapping in a plan view. In addition, the electrode 2 ′ provided below the insulating film 3 ′ and the sensitive film 8 of the biological substance sensitive part B is connected to the gate electrode 2 constituting the TFT element part A.

  The TFT element portion A has a bottom gate type TFT, and as shown in FIG. 1, a gate electrode 2 provided on the transparent substrate 1, a gate insulating film 3 provided on the gate electrode 2, and The oxide semiconductor film 4 provided on the gate insulating film 3, the source electrode 5 and the drain electrode 6 provided in a top contact form on both sides of the oxide semiconductor film 4, the oxide semiconductor film 4, and the source electrode 5 And a protective film 7 covering the drain electrode 6. On the other hand, as shown in FIG. 1, the biological substance-sensitive part B includes an electrode 2 ′ formed on the transparent substrate 1 together with the gate electrode 2 of the TFT element part A, and the TFT element part A on the electrode 2 ′. An insulating film 3 ′ formed together with the gate insulating film 3 and a sensitive film 8 provided on the insulating film 3 ′. The biological substance is placed on the sensitive film 8.

  A transparent biosensor 10B having a bottom-gate TFT shown in FIG. 2 includes a transparent substrate 1, a TFT element portion A provided on the transparent substrate 1, a protective film 7 covering the TFT element portion A, and It is composed of a living body related substance sensitive part B provided on the protective film 7. The TFT element part A and the biological substance-sensitive part B are provided side by side without overlapping in a plan view. In addition, the electrode 2 ′ provided below the insulating film 3 ′ and the sensitive film 8 of the biological substance sensitive part B is located above and below the gate electrode 2, the insulating film 3 ′, and the sensitive film 8 constituting the TFT element part A. Are connected via a wiring 2 "penetrating through the wiring.

  The TFT element portion A also has a bottom gate type TFT, and as shown in FIG. 2, since it has the same form as FIG. 1, its description is omitted here. On the other hand, as shown in FIG. 2, the biological substance-sensitive part B includes a transparent base material 1, an insulating film 3 ′ provided on the transparent base material 1, and a protective film 7 provided on the insulating film 3 ′. ', An electrode 2' provided on the protective film 7 ', and a sensitive film 8 provided on the electrode 2'. The biological substance is placed on the sensitive film 8 in the range where the electrode 2 ′ is provided in the sensitive film 8.

  A transparent biosensor 10C having a bottom-gate TFT shown in FIG. 3 has substantially the same form as FIG. The difference is that the electrode 2 ′ constituting the biological material sensitive part B extends to above the TFT element part A, and the rest is the same as in FIG. To do. The biological substance is placed on the sensitive film 8 in the range where the electrode 2 ′ is provided in the sensitive film 8.

(Transparent substrate)
If the transparent base material 1 is transparent, the kind and structure are not particularly limited, and a flexible material, a hard material, or the like is selected according to the application. Specific examples include glass, quartz, polyethylene, polypropylene, polyethylene terephthalate, polyethylene naphthalate, polymethacrylate, polymethyl methacrylate, polymethyl acrylate, polyester, polycarbonate, and the like. Usually, a glass substrate with ITO, a plastic substrate with ITO, or the like is preferably used. Note that a glass substrate, a plastic substrate, or the like in which a metal film or a transparent conductive film is formed as a gate electrode may be used.

  The definition of transparency should just be transparent to the extent that the biological substance mounted on the biological substance-sensitive part B can be observed from below the transparent substrate 1. For example, (i) when judging by reflectivity, it is preferable that the refractive index of each film is about 2 or less and the difference in refractive index is about 0.5 or less in the visible light wavelength range of 350 nm to 650 nm. ii) When judging by transmittance, it is preferable that the extinction coefficient k of each film is as low as about 0.1 or less in the visible light range of wavelength 350 nm to 650 nm. The thickness of the transparent substrate 1 is not particularly limited, but is usually about 1 μm to 1 mm. The shape of the transparent substrate 1 is not particularly limited, but is preferably a shape that can be used for microscopic observation, and examples thereof include a chip shape, a card shape, and a disk shape.

(Gate electrode)
As shown in FIGS. 1 to 3, the gate electrode 2 is provided as a gate electrode 2 in the TFT element part A, and is provided as an electrode 2 ′ in which the gate electrode 2 extends in the biological substance-sensitive part B. Is also patterned on the transparent substrate 1. Material for forming the gate electrode 2 may be transparent electrodes, for example, ITO (indium tin oxide), indium oxide, IZO (indium zinc _oxide), can be exemplified preferably a transparent conductive film of SnO 2, ZnO and the like. Note that a transparent conductive polymer such as polyaniline, polyacetylene, a polyalkylthiophene derivative, or a polysilane derivative may be used as long as it has desired conductivity.

  For the formation of the gate electrode 2, film forming means and patterning means corresponding to the kind of the gate electrode material and the heat resistance of the transparent substrate 1 are applied. For example, when forming the gate electrode 2 with a transparent conductive film, a sputtering method, various CVD methods, etc. can be applied as a film forming means, and photolithography can be applied as a patterning means. When a low temperature film formation is required for forming the gate electrode 2, a sputtering method or a plasma CVD method capable of forming a low temperature can be preferably applied as a film forming means. When the gate electrode 2 is formed of a conductive polymer, a vacuum deposition method, a pattern printing method, or the like can be applied as a film forming unit, and photolithography can be applied as a patterning unit. At the same time as forming the gate electrode 2, a circuit wiring group such as a gate electrode wiring, a ground wiring, and a power wiring may be formed of the same material as the gate electrode 2. The thickness of the gate electrode 2 and the thickness of the circuit wiring group (electrode or wiring) formed simultaneously with the formation of the gate electrode 2 are usually about 0.05 μm to 0.2 μm.

(Gate electrode UV cut function)
In the present invention, the gate electrode 2 included in the TFT element portion A cuts ultraviolet rays that adversely affect the oxide semiconductor film 4 constituting the TFT element portion A. By providing such a gate electrode 2, in the transparent biosensor 10 shown in FIGS. 1 to 3, ultraviolet light contained in light irradiated from below is emitted, and the gate electrode 2 disposed below on the irradiated light side emits ultraviolet light. In the transparent biosensor 20 shown in FIG. 4 and FIG. 5 to be described later, ultraviolet light contained in light irradiated from above is applied to the gate electrode 2 disposed on the upper side on the irradiated light side. Acts to cut. As a result, the oxide semiconductor film 4 can be prevented from being sensitive to ultraviolet rays, and the output signal from the oxide semiconductor film 4 can be prevented from fluctuating or decreasing. Information can be obtained accurately.

  The gate electrode 2 includes (i) a transparent electrode containing an ultraviolet cut material, (ii) a transparent electrode made of an ultraviolet cut material, and (iii) a transparent electrode having a band gap smaller than the band gap of the oxide semiconductor film 4. Or any one of them. “Ultraviolet cut material” means a material capable of absorbing or reflecting ultraviolet rays.

  When the transparent electrode (i) or (ii) is used as the gate electrode 2, examples of the material for forming the gate electrode 2 include an ultraviolet cut material such as ITO and ZnO. The gate electrode 2 containing these materials or the gate electrode 2 made of these materials is applied with film forming means and patterning means corresponding to the type of the forming material. The film forming means may be formed by sputtering, various CVD methods, coating or the like and then patterned by photolithography or the like. In addition, content in the case of containing an ultraviolet cut material is arbitrarily selected by the characteristic of the material to contain.

  When the transparent electrode of (iii) is used as the gate electrode 2, the gate electrode 2 is formed of a material having a band gap smaller than that of the oxide semiconductor film and a transparent gate. A material capable of forming the electrode 2 is used. Since the gate electrode 2 formed of such a material can cut the ultraviolet rays that have been cut by the oxide semiconductor film 4 until now, the incidence of the ultraviolet rays on the oxide semiconductor film 4 can be reduced. The influence based on it can be reduced as much as possible.

  For example, in the case where the oxide semiconductor film 4 is formed using an IGZO oxide semiconductor, the gate electrode 2 is preferably formed using a material having a band gap in the range of more than 3.1 eV and less than 4.05 V. Specifically, the band gap of the IGZO oxide semiconductor is 4.05 eV at the maximum, while the boundary between the visible light region and the ultraviolet light region is 400 nm with an energy of 3.1 eV. Therefore, the gate electrode 2 preferably absorbs ultraviolet light having a wavelength of less than 400 nm and is in a range smaller than the band gap of the IGZO oxide semiconductor. Accordingly, the band gap in the range of energy exceeding 400 nm light energy (3.1 eV) (greater than 3.1 eV) to energy less than the band gap of the IGZO oxide semiconductor (maximum 4.05 eV) (less than 4.05 eV). If the gate electrode 2 is manufactured using a material having the above, the gate electrode 2 can absorb light in the energy range, and the oxide semiconductor film 4 is not affected by ultraviolet rays.

  As a result, when the oxide semiconductor film 4 is formed of IGZO having a band gap of 4.05 eV, even if the oxide semiconductor film 4 is irradiated with light whose energy is less than 4.05 eV, the light is oxide. Electrons are not excited through the semiconductor film 4. On the other hand, when the oxide semiconductor film 4 is irradiated with light having energy greater than 4 eV, the light is absorbed by the oxide semiconductor film 4 to excite electrons. Therefore, the gate electrode 2 only needs to be made of a material that absorbs light of energy absorbed by the oxide semiconductor film 4, that is, ultraviolet rays. Since the energy of visible light having a wavelength of 400 nm is 3.1 eV (400 nm) to 1.55 eV (800 nm), light in these ranges is transmitted through the IGZO oxide semiconductor film 4 having a band gap of 4.05 eV. Since electrons are not excited, no adverse effects occur. The light energy E (eV) can be calculated by 1240 / λ (wavelength: nm).

  In this example, the oxide semiconductor film 4 is formed using IGZO having a band gap of 4.05 eV. However, the band gap varies depending on the oxide semiconductor material used. Therefore, in the same way as described above, a material constituting the gate electrode 2 is selected according to the band gap of the oxide semiconductor film 4 used. For example, examples of the transparent material that can be used for the gate electrode 2 include ITO (3.3 eV), IZO (3.3 eV), ZnO (3.2 eV), SnO (3.8 ev), and the like. Of these, ITO (3.3 eV), IZO (3.3 eV), and ZnO (3.2 eV) are preferable.

  On the other hand, an IGZO oxide semiconductor combined with such a material has an In: Ga: Zn ratio of 1.1: 0.9: 1 (3.77 eV) and an In: Ga: Zn ratio of 1: 1: 1 (3 .81 eV), In: Ga: Zn ratio is 0.7: 1.3: 1 (3.97 eV), In: Ga: Zn ratio is 0.5: 1.5: 1 (4.05 eV), In: The Ga: Zn ratio is 1.1: 0.9: 2 (3.61 eV), the In: Ga: Zn ratio is 1: 1: 2 (3.68 eV), and the In: Ga: Zn ratio is 0.7: 1. .3: 2 (3.79 eV), In: Ga: Zn ratio is 0.5: 1.5: 2 (3.85 eV), and the like.

As an oxide semiconductor other than the IGZO oxide semiconductor, an n-type semiconductor includes ZnO (3.37 eV), In ₂ O ₃ (3.75), Ga ₂ O ₃ (4.8 eV), SnO ₂ (3 .57 eV), and p-type semiconductors include CuAlO ₂ (3.5 eV), LaCuOS (3.1 eV), LaCuOSe (3.1 eV), SrCu ₂ O ₂ (3.2 eV), and the like. it can. In the present invention, since transparency is required, an IGZO oxide semiconductor is preferably used.

  For film formation of the gate electrode 2 made of the material described above, film formation means and patterning means corresponding to the type of the formation material and the like are applied. The film forming means may be formed by sputtering, various CVD methods, coating or the like and then patterned by photolithography or the like. In addition, content in the case of containing an ultraviolet cut material is arbitrarily selected by the characteristic of the material to contain.

The semiconductor characteristics were measured when the ITO film (band gap 3.3 eV), which is the ultraviolet cut material described here, was used as the gate electrode 2 and the oxide semiconductor film 4 was formed using IGZO (band gap 4.05 eV). Specifically, an IGZO oxide semiconductor film having a channel length between the source electrode and the drain electrode of 10 μm and a channel width of 100 μm was used. As UV light, SPECTROLINE LONGGIFE_TM FILTER HIGHEST ULTRAVILET INTENSITY GUARANTEED was used, and the distance between the semiconductor film and the UV light was 13 cm, and ultraviolet light of 365 nm was irradiated. At this time, the drain voltage is 1V fixed and measured semiconductor characteristics _(V G -I _D characteristic) when changing the gate voltage between the 15V~-15V. As a result of semiconductor characteristics when shielded with an ITO film and when not shielded, a difference of about 10 ³ cm / (V · s) at maximum was confirmed. When not shielded with the ITO film, the number of carriers increased due to ultraviolet irradiation, the leakage current increased, the OFF level increased, and the ON / OFF ratio deteriorated as compared with the case of shielding. Then, since the number of carriers increased, the transistor was easily turned on, and the threshold value _Vth shifted to minus. Furthermore, the threshold value _Vth has shifted to minus.

(Gate insulation film)
As shown in FIGS. 1 to 3, the gate insulating film 3 is provided as the gate insulating film 3 covering the gate electrode 2 in the TFT element part A, and the insulating film so as to cover the electrode 2 ′ in the biological substance sensitive part B. 3 'is provided. Various materials can be used for the gate insulating film 3 as long as it is transparent, has high insulating properties, has a relatively high dielectric constant, and is suitable as a gate insulating film. For example, silicon oxide such as silicon oxide, silicon nitride, or silicon oxynitride, nitride, oxynitride, or the like can be preferably exemplified. In addition, at least one or more of yttrium oxide, aluminum oxide, hafnium oxide, zirconium oxide, titanium oxide, tantalum oxide, niobium oxide, scandium oxide, and barium strontium titanate can be given. Particularly preferred are silicon oxides, nitrides or oxynitrides such as silicon oxide, silicon nitride or silicon oxynitride which are excellent in transparency.

  The gate insulating film 3 is formed by a film forming means and a patterning means corresponding to the type of gate insulating film material and the heat resistance of the transparent substrate 1. For example, when the gate insulating film 3 is formed of silicon oxide, nitride, oxynitride, or the like, a sputtering method or various CVD methods can be applied as the film forming unit, and photolithography can be applied as the patterning unit. When the gate insulating film 3 is required to be formed at a low temperature, a sputtering method or a plasma CVD method capable of forming at a low temperature can be preferably applied as the film forming means. The thickness of the gate insulating film 3 is usually about 0.1 μm to 0.3 μm.

(Oxide semiconductor film)
As shown in FIGS. 1 to 3, the oxide semiconductor film 4 is provided in a predetermined pattern on the gate insulating film 3 constituting the TFT element portion A in the TFT element portion A and above the gate electrode 2. It has been. The oxide semiconductor film 4 is not particularly limited as long as the oxide semiconductor film 4 is transparent and has a mobility that can be used as a channel region constituting the TFT element portion A. Even a film may be an oxide semiconductor film to be discovered in the future.

  Many of these transparent oxide semiconductor films 4 are sensitive to ultraviolet rays, such as an IGZO-based oxide semiconductor film, and are sensitive to ultraviolet rays contained in light irradiated when microscopically observing biological materials. The output signal from the oxide semiconductor film 4 may fluctuate or decrease. Therefore, it is possible to prevent the output signal from the oxide semiconductor film 4 from fluctuating or decreasing by cutting the ultraviolet rays with the gate electrode 2 having the ultraviolet ray cutting ability, and the signal of the biological substance acquired simultaneously with the microscopic observation Information can be obtained accurately.

Examples of the oxide constituting the oxide semiconductor film 4 include an amorphous oxide containing InMZnO (M is at least one of Ga, Sn, Al, and Fe) as a main constituent element. In particular, an InGaZnO-based amorphous oxide in which M is Ga is preferable. In this case, the ratio of In: Ga: Zn is preferably 1: 1: m (m <6). When Mg is further contained, the ratio of In: Ga: Zn _1-x Mg _x is preferably 1: 1: m (m <6) and 0 <x ≦ 1. The composition ratio is measured with a fluorescent X-ray (XRF) apparatus. In the case where the oxide semiconductor film 4 is formed using an oxide semiconductor material that is an amorphous oxide containing InMZnO, the oxide semiconductor film 4 can be preferably applied because it exhibits good light transmittance particularly in the visible light region. In particular, an InGaZnO-based amorphous oxide in which M is Ga is preferable.

The InGaZnO-based amorphous oxide exhibits an amorphous phase in a wide composition range of In, Ga, and Zn. The composition range stably showing the amorphous phase in this ternary system is In _x Ga _y Zn _z O _{(3x / 2 + 3y / 2 + z)} and the ratio x / y is in the range of 0.4 to 1.4, and the ratio It can be expressed such that z / y is in the range of 0.2-12. In addition, crystalline is shown with a composition close to ZnO and a composition close to In ₂ O ₃ .

Amorphous oxides include In _x Ga _1-x oxide (0 ≦ x ≦ 1), In _x Zn _1-x oxide (0.2 ≦ x ≦ 1), In _x Sn _1-x oxide ( It may be any amorphous oxide selected from 0.8 ≦ x ≦ 1) and In _x (Zn, Sn) _1-x oxide (0.15 ≦ x ≦ 1).

  An InGaZnO-based (hereinafter abbreviated as “IGZO-based”) oxide semiconductor film is preferably used because it transmits visible light and becomes a transparent film. Further, the IGZO-based oxide semiconductor film may be added with Al, Fe, Sn, or the like as a constituent element, if necessary. This IGZO-based oxide semiconductor film is preferably used for a thin film integrated circuit that requires transparency. In addition, since this IGZO-based oxide semiconductor film can be formed at a low temperature of about 150 ° C. from room temperature by sputtering (particularly RF sputtering), the glass transition temperature is less than 200 ° C. It can be preferably applied to a poor plastic substrate.

  For the formation of the oxide semiconductor film 4, film forming means and patterning means corresponding to the kind of the oxide semiconductor material and the heat resistance of the transparent substrate 1 are applied. For example, a sputtering method, a CVD method, or the like can be applied as a film forming unit, and photolithography can be applied as a patterning unit. However, when low temperature film formation is required, a sputtering method (particularly, RF sputtering method) The plasma CVD method can be preferably applied.

  Although the thickness of the oxide semiconductor film 4 is not generally specified because it is arbitrarily designed depending on the film formation conditions, it is usually preferably in the range of 10 nm to 150 nm, and preferably in the range of 30 nm to 100 nm. Is more preferable.

(Source electrode, drain electrode)
As shown in FIGS. 1 to 3, the source electrode 5 and the drain electrode 6 are patterned so as to be in top contact with both sides of the oxide semiconductor film 4 in the TFT element portion A. The source electrode material and the drain electrode material are transparent and are selected in consideration of ohmic contact with the source electrode connection portion (not shown) and the drain electrode connection portion (not shown) of the oxide semiconductor film 4. As the source electrode material and the drain electrode material, a metal film having good conductivity or a conductive oxide film is usually used. Examples of the metal film include a titanium film, an aluminum film, and a laminated film in which a titanium film is provided on the aluminum film. Examples of the conductive oxide film include ITO (indium tin oxide), indium oxide, and IZO (indium). Zinc oxide), transparent conductive films such as SnO ₂ and ZnO can be mentioned. Further, a conductive polymer such as polyaniline, polyacetylene, polyalkylthiophene derivative, polysilane derivative, or the like may be used as long as it has desired conductivity.

  For the formation of the source electrode 5 and the drain electrode 6, film forming means and patterning means corresponding to the type of electrode material and the heat resistance of the transparent substrate 1 are applied. For example, when the source electrode 5 and the drain electrode 6 are formed of a metal film or a conductive oxide, a vacuum deposition method, a sputtering method, or various CVD methods can be applied as a film forming unit, and photolithography is used as a patterning unit. Although it can be applied, when low-temperature film formation is required, a sputtering method or a plasma CVD method capable of low-temperature film formation can be preferably applied as a film forming means. Further, when the source electrode 5 and the drain electrode 6 are formed using a conductive polymer, a vacuum deposition method, a pattern printing method, or the like can be applied as a film forming unit, and photolithography can be applied as a patterning unit. In the process of forming the source electrode 5 and the drain electrode 6, it is preferable to simultaneously connect to the already formed circuit wiring group or form a new circuit wiring group with the same electrode material. The thickness of the source electrode 5 and the drain electrode 6 is usually about 0.1 μm to 0.3 μm.

(Protective film)
As shown in FIGS. 1 to 3, the protective film 7 is formed so as to cover the oxide semiconductor film 4, the source electrode 5, and the drain electrode 6 in the TFT element portion A. As the transparent protective film 7, an organic protective film such as a PVP (polyvinylpyrrolidone) film having a thickness of about 500 nm to 1000 nm, or a gas barrier inorganic protective film made of silicon oxide or silicon oxynitride having a thickness of about 100 nm to 500 nm. Etc. can be mentioned preferably. Alternatively, the oxide semiconductor film 4 may be formed using the same oxide semiconductor material as the constituent material of the oxide semiconductor film 4 described above.

  For the formation of the protective film 7, film forming means and patterning means corresponding to the kind of the protective film material and the heat resistance of the transparent substrate 1 are applied. For example, when an organic protective film is formed, a coating method or a vapor deposition method can be applied, and when an inorganic protective film is formed, a sputtering method or various CVD methods can be applied. In the case of patterning, photolithography can be applied.

(Sensitive membrane)
As shown in FIGS. 1 to 3, the sensitive film 8 is a pattern formed on the insulating film 3 ′ in the biological material sensitive part B. The sensitive film 8 is formed of a material on which a biological substance contained in the fluid to be inspected, such as cells, DNA, sugar chains, proteins, oxidoreductases, antigens or antibodies can be placed. Examples of the material for forming the sensitive film 8 include silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), tantalum oxide (Ta ₂ O ₅ ), and aluminum oxide (Al ₂ O ₃ ). The sensitive film 8 formed of these materials is an ion sensitive film and is appropriately selected according to the ion species to be measured. The sensitive film 8 may be a single layer or a laminated layer. In the case of a laminated layer, for example, a silicon nitride film may be provided on a silicon oxide film, or a tantalum oxide film may be further provided thereon. Good.

  If necessary, surface modification for immobilizing DNA, protein, sugar chain or the like can also be performed. A partition wall 9 to be described later is provided around the sensitive film 8, and a placement region for placing a biological substance contained in the fluid to be tested is provided on the channel region (not shown) of the oxide semiconductor film 4. ing.

  In addition, since the sensitive film | membrane 8 has insulation, you may utilize as a protective film which covers the gate electrode 2, for example. For the formation of the sensitive film 8, a film forming means and a patterning means corresponding to the kind of the sensitive film material and the heat resistance of the transparent substrate 1 are applied. For example, sputtering or various CVD methods can be applied, and photolithography can be applied as the patterning means.

  The thickness of the sensitive film 8 is usually about 50 nm to 500 nm. For example, a silicon oxide film having a thickness of 100 nm may be formed as a single layer, or a silicon nitride film having a thickness of 100 nm may be formed on a silicon oxide film having a thickness of 100 nm. Alternatively, a tantalum oxide film may be formed.

  As described above, in the transparent biosensor 10 having the bottom gate TFT, the ultraviolet light contained in the light irradiated from below the transparent biosensor 10 is cut by the gate electrode 2 having the ultraviolet cut function. As a result, the oxide semiconductor film 4 can be prevented from being sensitive to ultraviolet rays, and the output signal from the oxide semiconductor film 4 can be prevented from fluctuating or decreasing. Information can be obtained accurately.

[Transparent biosensor with top-gate TFT]
The transparent biosensor 20 shown in FIGS. 4 and 5 has a TFT element part A having a top gate type TFT and a biological substance sensitive part B. In the transparent biosensor 20 having the top-gate TFT, the constituent elements of the TFT element part A and the biological substance-sensitive part B including the gate electrode 2 having an ultraviolet cutting ability are the bottom parts shown in FIGS. This is the same as the case of the transparent biosensor 10 having a gate type TFT. Therefore, the same reference numerals are given to FIGS. 4 and 5, and the description thereof is omitted.

  A transparent biosensor 20A having a top-gate TFT shown in FIG. 4 includes a transparent base material 1, a TFT element part A and a biological substance sensitive part B provided on the transparent base material 1. The TFT element part A and the biological substance-sensitive part B shown in FIG. 4 are provided side by side without overlapping in a plan view. Further, the electrode 2 ′ provided below the sensitive film 8 of the biological substance sensitive part B is connected to the gate electrode 2 constituting the TFT element part A.

  The TFT element portion A has a top gate type TFT, and as shown in FIG. 4, the source electrode 5 and the drain electrode 6 provided on the transparent substrate 1 and the source electrode 5 and the drain electrode 6 An oxide semiconductor film 4 provided so as to be connected on both sides in a bottom contact manner, a gate insulating film 3 provided so as to cover the source electrode 5, the oxide semiconductor film 4 and the drain electrode 6, and a gate insulating film 3 It has a gate electrode 2 provided on top and a protective layer 7 provided on the gate electrode 2. On the other hand, as shown in FIG. 4, the biological substance-sensitive part B includes an insulating film 3 ′ formed on the transparent substrate 1 together with the gate insulating film 3 of the TFT element part A, and a TFT on the insulating film 3 ′. An electrode 2 ′ formed with the gate electrode 2 of the element part A, a protective film 7 formed with the protective film 7 of the TFT element part A on the electrode 2 ′, and a sensitive film provided on the protective film 7 8. The biological substance is placed on the sensitive film 8.

  In the transparent biosensor 20 </ b> A shown in FIG. 4, the gate electrode 2 having an ultraviolet cutting ability is provided above the oxide semiconductor film 4, so that the gate electrode 2 is irradiated from above the transparent biosensor 20. Cuts out ultraviolet rays contained in light. In the example of FIG. 4, the sensitive film 8 is provided in a region other than the TFT element part A in a plan view, but may be provided above the TFT element part A. By doing so, the mounting area of the biological substance on the sensitive film 8 can be increased and the observation range can be widened.

  A transparent biosensor 20B having a top-gate TFT shown in FIG. 5 includes a transparent base material 1, a TFT element part A and a biological substance sensitive part B provided on the transparent base material 1. The TFT element part A and the biological substance-sensitive part B shown in FIG. 5 are provided in a vertical positional relationship so as to overlap in plan view. Further, the electrode provided below the sensitive film 8 of the biological substance sensitive part B serves as both the detection electrode 2 ′ of the sensitive film 8 and the gate electrode 2 constituting the TFT element part A.

  The TFT element portion A has a top gate type TFT. As shown in FIG. 5, the source electrode 5 and the drain electrode 6 provided on the transparent substrate 1, and the source electrode 5 and the drain electrode 6 are provided. An oxide semiconductor film 4 provided so as to be connected on both sides in a bottom contact manner, a gate insulating film 3 provided so as to cover the source electrode 5, the oxide semiconductor film 4 and the drain electrode 6, and a gate insulating film 3 And a gate electrode 2 provided thereon. A protective film 7 may be provided between the gate electrode 2 and the sensitive film 8.

  On the other hand, the biological substance-sensitive part B is provided on the gate electrode 2 constituting the TFT element part A as shown in FIG. In the biological substance-sensitive part B, the gate electrode 2 of the TFT element part A is used in combination as a detection electrode 2 ', and a sensitive film 8 is provided on the detection electrode 2'. A partition wall 9 is provided at the periphery of the living body related substance sensitive part B provided with the sensitive film 8, and the body related substance contained in the fluid to be inspected is introduced into a region surrounded by the partition wall 9 and is transparent. Electrical signal information from the biosensor and microscopic observation are simultaneously performed. The “periphery” means an outer position that does not overlap with the detection electrode 2 ′ when the detection electrode 2 ′ provided in the biological substance-sensitive part B is viewed in plan. On the sensitive film 8, a biological substance contained in the fluid to be inspected, such as a cell, DNA, sugar chain, protein, oxidoreductase, antigen or antibody, is disposed between the partition walls 9.

  The partition wall 9 is provided on the sensitive film 8 at the periphery of the living body related substance sensitive part B. The partition wall 9 is for retaining a fluid to be inspected such as an aqueous solution or a culture solution on the sensitive film 8 and is provided at a predetermined height. The material for forming the barrier 9 is not particularly limited as long as it does not leak the fluid to be inspected. Specifically, according to the type of fluid to be inspected, various resin materials and metal materials can be selected and applied.

  In the transparent biosensor 20 </ b> B shown in FIG. 5, the gate electrode 2 having an ultraviolet cutting ability is provided above the oxide semiconductor film 4, so that the gate electrode 2 is irradiated from above the transparent biosensor 20. Cuts out ultraviolet rays contained in light.

  As described above, in the transparent biosensor 20 having the top-gate TFT, the ultraviolet light contained in the light irradiated from above the transparent biosensor 20 is cut by the gate electrode 2 having the ultraviolet cut function. As a result, the oxide semiconductor film 4 can be prevented from being sensitive to ultraviolet rays, and the output signal from the oxide semiconductor film 4 can be prevented from fluctuating or decreasing. Information can be obtained accurately.

DESCRIPTION OF SYMBOLS 1 Transparent base material 2 Gate electrode 2 'Detection electrode 2 "Connection wiring 3 Gate insulating film 3' Insulating film 4 Oxide semiconductor film 5 Source electrode 6 Drain electrode 7 Protective film 8 Sensitive film 9 Partition 10, 10A, 10B, 10C Transparent Biosensor 20, 20A, 20B Transparent biosensor A Thin-film transistor element part B Bio-related substance sensitive part

Claims (5)

  A transparent base material, a transparent thin film transistor element portion provided on the transparent base material, and a transparent biological material sensitive part, and a gate electrode included in the thin film transistor element portion constitutes the thin film transistor element portion. A transparent biosensor having an ultraviolet blocking function for a semiconductor film.   The gate electrode is (i) a transparent electrode containing an ultraviolet cut material, (ii) a transparent electrode made of an ultraviolet cut material, and (iii) a transparent electrode having a band gap smaller than the band gap of the oxide semiconductor film, The transparent biosensor according to claim 1, which is any one of the above.   The transparent biosensor according to claim 1, wherein the thin film transistor element portion has a bottom gate type thin film transistor structure or a top gate type thin film transistor structure.   The thin film transistor element portion has a bottom gate type thin film transistor structure, and a detection electrode connected to the gate electrode through an insulating film is provided above the thin film transistor structure, and the detection electrode cuts the ultraviolet ray with respect to the oxide semiconductor film. The transparent biosensor according to claim 1, which has a function.   The transparent biosensor according to claim 1, wherein the oxide semiconductor film is an IGZO-based oxide semiconductor film.

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