JPS5924244A - Multi-sensor manufacturing method - Google Patents

Abstract

PURPOSE:To form a plurality of responsive gates independently, by a method wherein a liquid prepared by dissolving ion responsive substance in a proper solvent along with a film matrix material is blown to a gate by an ink jet system to be repeatedly applied thereto in such a manner that the kind of the ion responsive substance is variously changed. CONSTITUTION:A first unit 21 has a gate 21 for a comparison electrode and said gate is coated with an org. polymer film not responsive to an ion. Each gates of other sensor units 23, 25, 27 are coated with ion selecting films respectively responsive to a different kind of ions. The coating of each ion selecting film is performed by such a method that liquid droplets 45 are intermittently blown out from a nozzle 44 and, after passed through charging electrodes 46, the charged liquid droplets are blown out between polarization electrodes 47. In general, voltage is applied to the charging electrodes 46 and the polarization electrodes 47 and the liquid droplets are guided to a gutter 48. By pulsewise cutting off voltage applied to the charging electrodes 46, the liquid droplets are guided to the objective gate on a substrate. A solvent is evaporated to form an ion selecting film.

Description

[Detailed Description of the Invention] The present invention relates to a field effect transistor (hereinafter referred to as FET)
The present invention relates to an ion sensor using a multi-ion sensor, and particularly to a multi-ion sensor and a method for manufacturing the same.

FETf: Since the principle of the ion sensor used was confirmed by Bergreid, sensors capable of selectively detecting various ions have been developed. This ion sensor is
It is made by coating a sensitive gate with an ion-selective membrane. Dip coating methods and direct casting methods are known as methods for applying ion-selective membranes made from organic materials to this sensitive gate (U, Oesch, S, Caras).
and J., Janata H., pield.
Effect Transistors Sensi
tive to Sodium and A,
rnmonium.

Anal, Chem, 1981, 53.1983-19
86). In addition, methods for applying inorganic materials include C,
VD (Chemical vapor 1)ep
ositelon) method and dip coating method are used.

In all of the examples reported so far, one or two PET gates are formed on a substrate, and one ion-sensitive gate is formed. Therefore, when using the conventional ion-sensitive gate formation method for multi-sensors having multiple sensitive gates on one common substrate, it is difficult to make each gate independent so as not to interfere with each other. be.

An object of the present invention is to provide an F'ET multi-ion sensor and its manufacturing method, in which ion selective membranes are coated on a plurality of gates formed on a common substrate so as not to overlap with each other, and there is no mutual interference. .

In the present invention, a sensitive film is applied only to minute portions by spraying a liquid solution dissolved in a suitable solvent A as small droplets onto the target gate using an inkjet method, together with the entire film base material of the ion-sensitive material. The idea is to repeatedly apply different types of ion-sensitive materials to form a plurality of sensitive gates independently.

Examples of the present invention will be described below.

FIGS. 1 to 3 show one PET sensor that is a constituent unit of a multi-sensor. When a plurality of sensitive gates are formed on a common substrate, each element must be electrically independent. Therefore, the present invention adopts the following element configuration.

As shown in FIG. 1, a sensor unit 2 is mounted on a common board 1.
are formed, and lead wires 4 and contacts 5 are also formed on the substrate by vapor deposition or the like. Sensor unit 2
The size is approximately 50 μm×(200 to 400) μm. Further, when the common substrate is made of P silicon as shown in FIG. 2, the F'ET gate portion is dug down to form the insulating film 7, and then the silicon P layer 13 is formed again. Thereafter, a layer 8 is formed by diffusion to form a drain/source. An oxide film layer 9, an insulating film layer 10, and an ion selection film 11 are coated on the top of the drain source to form a sensor unit.

FIG. 3 shows a sensor unit If made of silicon on sapphire (sos>m). The common substrate 12 is made of sapphire, and a P silicon layer 7 is formed on top thereof by an epitaxial growth method. The drain and gate 8 are formed by a diffusion method. On top of it, there is an oxide film layer 9, as in the case of FIG.
An insulating film 10° and an ion sensitive film 11 are applied.

FIG. 4 shows a multi-ion sensor in which four sensor units are formed on a common substrate by the method described above. The first unit 21 has a gate 22 for comparison electrode. An organic polymer film that does not respond to ions or the like is applied to the gate. Each gate of the other sensor units 23, 25, 27 is coated with an ion-selective membrane that responds to different types of ions.

A method of applying an ion selective membrane according to the present invention is shown in FIG.

This method has been used in conventional inkjet printers, in which droplets 45 are intermittently blown out from a nozzle 44, passed through a charging electrode 46, and then blown out between deflection electrodes 47. Usually, a voltage is applied to the charging electrode 46 and the deflection electrode, and the droplets are guided to the gutter 48. By cutting off the voltage applied to the charging electrode 46 in a pulsed manner, the droplet is guided to the intended gate on the substrate. At this time, a mask material 40 having a small-diameter opening 41 may be used to prevent errors in the apparatus. The solvent is evaporated to form an ion-selective membrane.

The inventors of the present invention prototyped a multi-sensor made from a substrate with a diameter of 1.5 m. The size of the sensor unit is 50μm
x 300μm, gate part is 50μm x 50μm
It was set as m. As shown in FIG. 4, four sensor units and one gold electrode 29 were formed on the substrate. A gate film was formed using the organic film coating apparatus shown in FIG. A polyimide amide resin was used as the sensitive membrane for the reference electrode, and this was dissolved in dimethylformamide and placed in a container 42 in FIG. 5 as a liquid. As the ion-selective membrane, a liquid in which palinomycin for the K+ electrode and a quaternary ammonium salt for the Na+ electrode and the combined ligand T-electrode were dissolved in tetrahydrofuran together with a plasticizer and polyvinyl chloride (PVC) was used. .

The diameter of the droplet blowing nozzle was 25 μm. An ultrasonic oscillator 43 was used to blow out the droplets, and normally the ultrasonic oscillator was operated continuously. Each solution was sprayed onto the gate by cutting off the voltage of the charged electrode in a pulsed manner, and the film thickness was adjusted by the number of sprays. One droplet has a diameter of approximately 50 μm on the gate.
, so the number of droplets should be 1 to 3, and the spread of the film on the gate, ! lll was set within 100 μm. After applying the droplets, the solvent was evaporated at room temperature to form a sensitive film.

In the method of coating the sensitive gate shown in this example, the ion selection film and the reference electrode film can be formed only on the target gate, and different types of ion sensors can be formed. . Therefore, the selectivity of each ion sensor is equivalent to that when formed on a single substrate. Also,
The film thickness can be controlled by the number of droplets sprayed, making it possible to create a multi-ion sensor with good reproducibility.

As described above, according to the present invention, ion selective membranes can be applied to several gates formed on a common substrate without overlapping each other, and mutual interference will not occur.

[Brief explanation of drawings]

Figure 1 is a diagram showing the principle configuration of the present invention, Figures 2 and 3 are diagrams showing an embodiment of the present invention, Figure 4 is a diagram showing an embodiment of a multi-ion sensor, and Figure 5 is a diagram showing a gate formation method. FIG. ■... Board, 2... Sensor unit (FET), 3
...Sensitive gate, 4...Lead, 5...Contact, 6...P silicon substrate, 7...Insulating film, 8...
- Drain, source, 9... Oxide film, 10... Insulating film, 11... Ion selective membrane, 12... Sapphire substrate, 13... P silicon, 21... Reference electrode unit, 23 , 25.27... Ion sensor unit, 22
...Comparison gate, 24°26.28...Ion sensitive gate, 29...Gold electrode. , //

Claims (1)

[Claims] 1. A multi-ion sensor in which a plurality of ion-selective insulated gate field effect transistors are formed on a substrate,
An N-type silicon drain/source part is formed on the surface layer of the well-shaped or island-shaped P-type silicon, and a plurality of sensor units, each of which is covered with an oxide film and an insulating film, are formed on the substrate, and individual sensor units are formed. A field effect transistor type multi-ion sensor, characterized in that at least one gate film for comparison electrodes and a plurality of gate films for ion selection electrodes are formed for each gate film. 2. A first step of forming a plurality of well-shaped P-type silicon or island-shaped P-type silicon on a substrate made of silicon or sapphire, and forming drain/source parts made of n-type silicon on the surface layer of the P-type silicon. Second to do
After the formation of the 20th step, a third step of forming a sensor unit If by covering the upper part with an oxide film and an insulating film, and forming a polymer having no ion selectivity on the sensitive gate of each sensor unit. A liquid in which the membrane material is dissolved in a suitable volatile solvent or a liquid in which at least an ion-selective substance and a polymeric membrane material are dissolved in a suitable volatile solvent is made into a particle size corresponding to the gate part using a nozzle. e [a fourth step of spraying onto the sensitive gate through a mask material having an opening in contact with or at a position corresponding to the sensitive gate, and after the spraying in the fourth step, the solvent is evaporated and at least 1 A method for manufacturing a field effect transistor type multi-ion sensor, comprising a fifth step of forming a gate film for comparison electrodes and a plurality of ion selection electrodes.