JPS62163959A - Preparation of electric field effect type semiconductive sensor - Google Patents

Abstract

PURPOSE:To make it possible to prevent delamination of a polymer film over a long period of time, by bonding a silane coupling agent having an optically active group at the terminal thereof. CONSTITUTION:Source and drain regions 2, 3 are formed to the surface of a silicon substrate 1 and a gate insulating film wherein a SiO2 film 4 and a Si3N4 film 5 are successively laminated is further formed thereon. Next, a silane coupling agent 6 having an optically active group at the terminal thereof is bonded to the Si3N4 film 5 being the upper layer of the gate insulating film. Further, an uncured polymer material is applied and, thereafter, the optically active group is irradiated with light to form a highly reactive intermediate which is, in turn, reacted with the polymer material to form a cured polymer film 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a method for manufacturing a field-effect semiconductor sensor.

[Conventional technology]

In recent years, the importance of chemical sensors that respond to specific chemical substances has been recognized. Ion-selective electrodes and enzyme electrodes are conventionally known as such chemical sensors.

The basic principle of the ion-selective electrode is to measure the ion concentration using the potential generated at both ends of an ion-sensitive membrane. This ion-selective electrode has a structure including an ion-sensitive membrane, an electrolytic solution (internal solution), and an internal electrode.

However, ion-selective electrodes generally have high electrode impedance, and this tendency increases as the size becomes smaller. Furthermore, miniaturization is extremely difficult because the internal liquid and internal electrodes are essential.

The basic principle of an enzyme electrode is to use an electrochemical device to measure the substances consumed or produced in a specific reaction caused by an enzyme immobilized on a polymer membrane and convert it into an electrical signal. It is.

The electrochemical devices mentioned above include 02, H2O2
, CO2, NH, , H+, NH+, etc., and electrodes selectively sensitive to ions, respectively, are used. In other words, the enzyme electrode has an enzyme-immobilized membrane and has a structure in which a gas sensor or an ion sensor is used as an internal electrode.

However, since most gas sensors and ion sensors have internal liquids and internal electrodes, it is extremely difficult to miniaturize them from the viewpoint of sensitivity and structure.

For these reasons, in recent years, ion sensors using field-effect transistors (hereinafter referred to as FETs) have been developed.
FETs are attracting attention. The FET is a low impedance device having an fyg function and can be manufactured using semiconductor manufacturing technology, so it has the advantage of being easily miniaturized and mass-produced at low cost.

This (7) ISFET was first proposed by Bergveld (1970), and later by Matsuo and Jan.
TA et al. have conducted extensive research and proposed ion sensors in which a polymer film such as glass or PVC is formed on the surface of the gate part, or enzyme sensors in which enzymes are immobilized on the polymer film on the surface of the gate part. There is.

Currently, they are used not only as ion sensors and enzyme sensors, but also as sensors for a wide range of chemical species.

FIG. 2 shows a cross-sectional view of the 15FET.
Source and drain regions 2 and 3 are formed on the surface of the silicon substrate 1, and furthermore, for example, a 5i02 film 4 and an S
A gate insulating film such as a t3N4 film 5 is formed.

As the gate insulating film, 5i02. A-mi, 03, Ta2e
A laminated material of one or two or more of inorganic materials such as S, 5t3N4, etc. is used.

Generally, the combination 5i02-Si3N4 shown in FIG. 2 or S f O2S i3 N 4- T a 2
Since these gate insulating films are particularly sensitive to H+, 1For example, the I S FET shown in Figure 2 can be used as it is as an H+ ion sensor, with a current of about 60 mA/pH. sensitivity can be obtained.

In order to use it as an ion sensor other than H+ or an enzyme sensor, an ion-sensitive membrane made of a polymer membrane or an enzyme-immobilized membrane in which an enzyme is immobilized on a polymer membrane is formed on the gate insulating film.

[Problem that the invention seeks to solve]

By the way, when forming a polymer film on the gate insulating film,
For example, the dip method is used. When this dip method is used, initially the response is close to the Nernst response,
It exhibits a linear relationship between concentration and potential and has good performance. However, as time passes, the film deteriorates as the film peels off, etc. This is because the compatibility between the gate insulating film, which is an inorganic material, and the polymer film, which is an organic material, is not good.

Therefore, research is being conducted to chemically modify the surface of the gate insulating film by bonding, for example, a silane coupling agent to improve its affinity with polymeric materials.

That is, the silane coupling agent has St as a central atom, and this St has three alkoxy groups such as CH30- and C2H50-, and an alkyl group having an amine group, mercapto group, epoxy group, vinyl group, propenyl group, etc. at the end. , polyether, etc. have a bonded structure. and,
The former alkoxy group reacts with -OH groups, 5ixO groups, 5i-0-Si groups, etc. on the surface of the gate insulating film, which are inorganic materials, while the latter functional groups, such as amine groups, react with organic materials, such as polymeric materials. Silane coupling agents have affinity for both inorganic and organic materials.

Therefore, if such a silane coupling agent is used, it can be reacted with polymeric materials having a wide variety of functional groups, preventing the peeling of the polymeric film formed on the gate area and maintaining good performance over a long period of time. Performance may be maintained.

However, even if a silane coupling agent is used, the period of time during which the peeling of the polymer film can be prevented may not be very long. Therefore, the above effects cannot be expected.

The present invention has been made in order to solve the above-mentioned problems, and it manufactures a field-effect semiconductor sensor that can prevent peeling of a polymer film and maintain good performance over a long period of time. The purpose is to provide a way to obtain.

[Means and effects for solving the problems] The method for manufacturing a field-effect semiconductor sensor of the present invention includes a step of bonding a silane coupling agent having a photoactive group at the end to a gate insulating film, and This method is characterized by comprising a step of applying a polymer material and a step of forming a hardened polymer film by irradiating light.

If this method is used, the intermediate produced by irradiating the photoactive group introduced at the end of the silane coupling agent with light is extremely reactive, so it is possible to form a much stronger bond than conventional methods. Furthermore, even when a chemically stable polymer material is used, peeling of the film can be prevented for a long period of time, and good performance can be maintained.

The method of the present invention will be explained in more detail below.

In the present invention, first, as shown in FIG. 1(a), source and drain bond regions 2.3 are formed on the surface of the silicon substrate 1, and further, for example, an St02 film 4 and st, Na115I
Next, as shown in the same figure (b), on the gate 1 insulating film (in this case, the upper layer 5t3N, film 5), a gate insulating film having a photoactive group at the terminal is formed by sequentially stacking 5t3N and film 5. A silane coupling agent 6 is bonded. Furthermore, as shown in the same figure (C), an uncured polymer material (bulk may be used,
After coating the photoactive group (which may be a solution), a highly reactive intermediate is generated by irradiating the photoactive group with light, and this intermediate is reacted with the polymer material to form a cured polymer film 7. ``To form.

In the process shown in FIG. 1(b), in order to bond the silane coupling agent 6 having a photoactive group to the gate insulating film, 1. After bonding a normal silane coupling agent to the gate insulating film,
Either convert the terminal functional group into a photoactive group, or (2) use a silane coupling agent into which a photoactive group has been previously introduced.

Either of these methods is used.

In addition, the photoactive groups introduced include azide, ketene,
Examples include ketones, ethers, diazo groups, and the like.

In either of the above cases ① and ②, in order to introduce a photoactive group to the terminal of the silane coupling agent, the following (a) addition reaction or elimination reaction, or (b) the terminal of the silane coupling agent is performed. A reaction between a functional group and a compound having a thermally functional group and a photoactive group is used.

! p, NaN, +H, O-zH-CH2N3\.

/ H -S:C-0+NH(C2H5)iCJl-(b) H20 -NH2+ HOCO--NHCO--HC sentence-NH2+ C standing Co-= -NHCO--HCf
I.

-NH2+ Cf1. CH, ---NHCH2-5-
``13H+ CH2-CH---H- CH30H -OH+ CH30---0- Azide (triazo;
N3), ketene (ketoketene or aldoketene; =C=
C-0), diazo group (20-N2), etc. are shown in Figure 1(c).
By being irradiated with light in the process, nitrene (-N:) and carbene (=C:
) is generated.

hυ −N3 + −N: + N2 c=c=o2≧C:+GO hυ ・・−CHN2 + −CH+ N2 The nitrene produced as above is a highly active reaction intermediate, and is The carbon of the methyl group is very stable under the conditions
It even reacts with hydrogen (C-H) bonds. It is known that carbenes having an isoelectronic structure with this nitrene also exhibit high activity.

For example, one of the simplest carbenes, methylene (:
Taking CH2) as an example, this methylene can be used for addition reactions to double bonds, insertion reactions to C-H bonds, and
A hydrogen abstraction reaction as shown in the following formula also occurs.

:CH2+ c) (3c) I,
φCH3+ -CH2CH3 In the above abstraction reaction, the two generated free radicals combine to generate propane.

A series of reactions such as hydrogen abstraction from the saturated hydrocarbon and the bonding of the two free radicals were naturally generated by irradiating the photoactive group at the 6-terminus of the silane coupling agent bonded to the gate insulating film. It also occurs between the highly active reaction intermediate and the main chain polymethylene chain or side chain of the coated polymer material. Therefore, as shown in the formula below, even if there is no functional group in the polymer material, the gate insulating film and the polymer material can be strongly bonded via the silane coupling agent 6, resulting in highly cross-linked A hardened polymer film 7 can be formed.

~h: +~CH2CH2CH2~ Moreover, when manufacturing an enzyme sensor, the enzyme may be further immobilized on the polymer membrane 7 using a conventional method.

Polymer materials used include polyvinyl chloride (PVC), epoxy resin, silicone resin, etc. in the case of ion sensors, and cellulose-based PVC such as polyacrylamide, acetyl cellulose, etc. in the case of enzyme, immunology, and microbial sensors. Aminated acrylonitrile, polyacrylic m
etc. can be mentioned.

In addition, examples of photoactive groups having the above-mentioned effects include carbon-carbon double bonds (-C=C-, ene), carbon-oxygen double bonds (C=C, ketones, aldehydes, etc.). ) Also includes double bonds with equal π electrons and nityl bonds (-C-O-C-) with non-bonding electron pairs. For example, in a double bond, the π bond is cleaved by the action of light. , a biradical, which is a reaction intermediate, is generated according to the following formula.

7 CmCC-Rinimin-dζ Photoactivity can be increased by bonding an electron-donating group or an electron-withdrawing group to the carbon of the double bond or its neighboring atoms. In addition, diphenyl ketone (@-CO-@
) can further enhance the photoactivity of double bonds and ether bonds.

In addition to the above, the following photoreactions that generate free radicals are known.

RONO-RO-+ -No (R is Furuki jL4)
ROX -RO-+ By using a method of forming a polymer film that is cured by irradiation with light, it is possible to form much stronger bonds than conventional methods, and even when using chemically stable polymer materials, it can be used for a long period of time. Peeling of the film can be prevented over time, and good performance as a chemical sensor can be maintained.

〔Example〕

The present invention will be explained in detail below. In the following examples, n-shaped source and drain regions are formed on the surface of a p-type silicon substrate, and 5i
A gate insulating film formed by sequentially laminating a 02 film and a Si3N film was used.

Example 1 First, 3 was applied as a silane coupling agent on the Si3N4 film.
-Aminopropyltriethoxysilane H2NCH2CH
An amino group was introduced by bonding 2CH2Si (OC2Hg)3. Next, this terminal 7mino group and 2-azido 1
-Iodo 2-methylpropane ICH2C(CH,)2-N.

Azide was introduced by reacting with iodine. Subsequently, a solution of polyvinyl chloride (PVC) in tetrahydrofuran (THF) containing palinomycin and dioctyl adipate (DOA) was applied.Then, light was irradiated with a high-pressure mercury lamp to form a cured polymer film.

Example 2 First, a mercapto group was introduced by bonding 3-mercaptopropyltriethoxysilane H3CH2CH2CH2Si (OC2Hs)i as a silane coupling agent onto S i 3N atlI. Next, this terminal mercapto group and 2- The azide was introduced by reacting the azide with 2-butene.

Next, palinomycin and dioctyl phthalate (D
OP) dissolved silicone resin (KEl 03 R
TV, manufactured by Shin-Etsu Silicone Co., Ltd.) and a crosslinking agent (Catalys
103) was applied, and then irradiated with light using a high-pressure mercury lamp to form a cured polymer film.

Example 3 First, 3 was applied as a silane coupling agent on the Si3N4 film.
An epoxy group was introduced by bonding -glycidoxyprobyltriethoxysilane. Next, this terminal epoxy group was reacted with sodium azide (N a N 3 ) in the presence of water, thereby converting the epoxy group into an azide. Subsequently, a toluene solution of polystyrene containing palinomycin and dioctyl adipate (CD OA) was applied. Next, light irradiation was performed using a high-pressure mercury lamp to form a cured polymer film.

When the chemical sensors of Examples 1 to 3 obtained as described above were used, the peeling of the polymer membrane could be prevented for a long period of time, and the performance as a chemical sensor could be maintained, resulting in a longer service life than before. It was confirmed that there was a significant improvement.

〔Effect of the invention〕

As described in detail above, according to the method of the present invention, it is possible to manufacture a field-effect semiconductor sensor that can prevent peeling of the polymer film and maintain good performance over a long period of time.

[Brief explanation of drawings]

FIGS. 1C to 1C are cross-sectional views showing an overview of the method of the present invention, and FIG. 2 is a cross-sectional view showing the basic structure of an ISFET. 1... Silicon substrate, 2.3... Source, drain region, 4... Si02 film, 5... Si3N4 film,
6... Silane coupling agent having a photoactive group at the end, 7... Polymer film. Applicant's representative Patent attorney Atsushi Tsuboi Procedural amendment June 27, 1986 Michibe Uga, Commissioner of the Patent Office 1, Indication of the case Patent application No. 1983-5583 2, Name of the invention Manufacture of field-effect semiconductor sensor Method 3. Relationship with the person making the amendment Patent applicant Olympus Optical Industry Co., Ltd. 4. Agent 6.4 Positive object 7. Contents of amendment Device” should be replaced with “Low output impedance device, 1
I am corrected. (2) On page 5, line 9 of the specification, “approximately 60 mA/PHJ
``Correct it to approximately 60 mV/pHJ.'' (3) Delete ``r FA, /

Claims (4)

[Claims] (1) Source and drain regions formed on the surface of a semiconductor substrate, a gate insulating film formed on the substrate, and a high temperature electrode formed on the gate insulating film that is selectively sensitive only to a specific substance to be measured. In manufacturing a field effect semiconductor sensor having a molecular film, a step of bonding a silane coupling agent having a photoactive group at a terminal to the gate insulating film;
1. A method for manufacturing a field-effect semiconductor sensor, comprising the steps of applying an uncured polymer material and forming a cured polymer film by irradiating with light. (2) Manufacturing a field-effect semiconductor sensor according to claim 1, characterized in that a silane coupling agent is bonded to the gate insulating film, and a photoactive group is introduced by reaction with the terminal functional group of the silane coupling agent. Method. (3) A method for manufacturing a field-effect semiconductor sensor according to claim 1, characterized in that a silane coupling agent having a photoactive group introduced at its terminal in advance is used. (4) The method for manufacturing a field-effect semiconductor sensor according to claim 1, wherein the photoactive group is an azide, ketene, ketone, ether, or diazo group.