KR102163118B1 - Nano fet sensor and system by using the same - Google Patents

Abstract

The present invention relates to a field effect transistor sensor capable of adjusting the measurement sensitivity by itself, and a system using the same. The field effect transistor sensor includes: a substrate gate; a first gate oxide positioned on top of the substrate gate; a field effect transistor (FET) channel positioned on top of the first gate oxide; a second gate oxide positioned on top of the channel; and an upper gate positioned on top of the second gate oxide.

Description

Nano field effect transistor sensor and system using the same {NANO FET SENSOR AND SYSTEM BY USING THE SAME}

The present invention relates to a sensor including a nano field effect transistor and a system using the same.

Recently, sensors of various structures have been developed to detect chemical and biomaterials. Among these sensors, research on a field effect transistor (FET) using an upper gate having a high input impedance and amplification factor is being conducted.

In the case of using such a FET as a sensor, the cost and time are lower than that of the conventional method, and it has the advantage of excellent compatibility due to easy grafting with an integrated circuit (IC)/MEMS process.

According to a conventional field effect transistor, a method of forming a gate insulating layer on a silicon substrate, forming a sensing layer on the upper portion of the gate insulating layer, and forming a control electrode on the upper portion of the sensing layer is mainly used. The sensing principle is that the capacitance or work function of the sensing layer changes before and after sensing, and the effects of charge generation/extinction appear. Changes. By reading this change in drain current, the degree of detection can be quantitatively expressed.

At this time, if the concentration of the object to be detected is too high, an insulation breakdown phenomenon may occur due to electrostatic shock, and if the concentration is too low, measurement may be impossible. Accordingly, there is a need for a structure in which the gate voltage is initialized to protect the device while controlling the measurement sensitivity by itself.

The technical problem to be solved by the present invention is to provide a field effect transistor sensor that operates stably without static shock even at a large amount of ions/gas concentration, and a sensing system using the same.

In addition, it is to provide a field effect transistor sensor capable of self-diagnosing whether a sensor element is operating normally and capable of adjusting measurement sensitivity by itself.

The technical problem to be solved is not limited to the technical problems as described above, and other technical problems may exist.

In order to solve the above technical problem, a field effect transistor sensor according to an embodiment of the present invention includes a substrate gate, a first gate oxide positioned above the substrate gate, and a field effect positioned above the first gate oxide. A transistor (FET) channel, a second gate oxide positioned above the channel, and an upper gate positioned above the second gate oxide.

In the field effect transistor sensor according to an embodiment, the substrate gate may operate as a sensing gate for detecting ions or gases.

In the field effect transistor sensor according to an embodiment, the upper gate may operate as a sensitivity control gate for adjusting the detection sensitivity of ions or gases.

In the field effect transistor sensor according to an embodiment, the first gate oxide may be thicker than the second gate oxide.

In the field effect transistor sensor according to an embodiment, a length of the substrate gate may be longer than a length of the channel, and a length of the upper gate may be shorter than a length of the channel.

In the field effect transistor sensor according to an embodiment, the field effect transistor sensor further includes a switch connected to the substrate gate and capable of changing the substrate gate to one of a floating state and a state for self-diagnosis. I can.

In the field effect transistor sensor according to an embodiment, the switch may be initialized by grounding the substrate gate or connecting a specific voltage V _bg in response to a case where a current of a predetermined value or more flows through the channel.

In the field effect transistor sensor according to an embodiment, the substrate gate may further include a conductor packaging capable of detecting gas or ions.

A field effect transistor gas detection sensor according to an embodiment of the present invention includes: a conductor packaging, a gas detection film, a spacer forming a space between the conductor packaging and the gas detection film, a substrate gate positioned above the gas detection film, A first gate oxide positioned above the substrate gate, a field effect transistor (FET) channel positioned above the first gate oxide, a second gate oxide positioned above the channel, and a top positioned above the second gate oxide It may include a gate.

In the field effect transistor gas detection sensor according to an embodiment, the upper gate may operate as a sensitivity control gate for adjusting the detection sensitivity of the gas.

In the field effect transistor gas detection sensor according to an embodiment, the first gate oxide may be formed to be thicker than the second gate oxide.

In the field effect transistor gas detection sensor according to an embodiment, the length of the substrate gate may be longer than the length of the channel, and the length of the upper gate may be shorter than the length of the channel.

The field effect transistor gas detection sensor according to an exemplary embodiment may further include a switch connected to the substrate gate to change the substrate gate to one of a floating state and a state for self-diagnosis.

In the field effect transistor gas detection sensor according to an embodiment, the switch may reset the substrate gate by grounding the substrate gate or connecting a specific voltage V _bg in response to a case in which a current of a predetermined value or more flows through the channel.

The disclosed technology can have the following effects. However, since it does not mean that a specific embodiment should include all of the following effects or only the following effects, it should not be understood that the scope of the rights of the disclosed technology is limited thereby.

According to an embodiment of the present invention, a gate electrode located above and below a nanochannel of a field effect transistor sensor may be used as an electrode for controlling measurement sensitivity and a sensing electrode.

According to an embodiment of the present invention, it is possible to self-diagnose whether or not it is in a normal state through a voltage change of the substrate gate electrode of the field effect transistor sensor, and to prevent destruction of the device due to excessive ion/gas concentration. .

1 is a configuration diagram illustrating a field effect transistor sensor according to an embodiment of the present invention.
2 is a configuration diagram illustrating a more specific configuration of a field effect transistor sensor according to an embodiment of the present invention.
FIG. 3 is a diagram illustrating a view of the field effect transistor sensor of FIG. 2 viewed from above.
4 is a view for explaining the IV characteristic of the field effect transistor sensor according to an embodiment of the present invention.
5 is a diagram for explaining an IV characteristic according to an upper gate voltage in a field effect transistor sensor according to an embodiment of the present invention.
6 is a diagram illustrating an operation of a switch in a field effect transistor sensor according to an exemplary embodiment of the present invention.
7 is a diagram illustrating an initialization operation of a substrate gate in a field effect transistor sensor according to an embodiment of the present invention.
8 is a graph illustrating a reaction operation for negative ions after applying a constant voltage to an upper gate in the field effect transistor sensor according to an embodiment of the present invention.
9 is a diagram for explaining packaging of a field effect transistor sensor according to an embodiment of the present invention.
10 is a diagram illustrating a gas detection sensor using a field effect transistor sensor according to an embodiment of the present invention.
11 is a configuration diagram illustrating a field effect transistor sensor according to a second embodiment of the present invention.

Since the present invention can make various changes and have various embodiments, specific embodiments are illustrated in the drawings and will be described in detail in the detailed description. However, this is not intended to limit the present invention to a specific embodiment, it is to be understood to include all changes, equivalents, or substitutes included in the spirit and scope of the present invention.

In describing each drawing, similar reference numerals are used for similar elements. Terms such as first and second may be used to describe various elements, but the elements should not be limited by the terms. These terms are used only for the purpose of distinguishing one component from another component.

For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The term "and/or" includes a combination of a plurality of related stated items or any of a plurality of related stated items.

Unless otherwise defined, all terms including technical or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in this application. Shouldn't.

Hereinafter, a field effect transistor sensor according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a configuration diagram illustrating a field effect transistor sensor according to an embodiment of the present invention.

Referring to FIG. 1, a field effect transistor sensor according to an embodiment includes a substrate gate 110, a first gate oxide 120 positioned above the substrate gate 110, and an upper portion of the first gate oxide 120. A field effect transistor (FET) channel 130 positioned, a second gate oxide 140 positioned above the channel 130, and an upper gate 150 positioned above the second gate oxide 140. I can. Here, the field effect transistor sensor may include source 160 and drain 170 electrodes connected through the channel 130. Here, the electrode voltage of the upper gate 150 may be V _g , and the electrode voltage of the substrate gate 110 may be V _bg .

According to an embodiment, ions or gas molecules may be detected using a field effect transistor sensor. The nano field effect transistor sensor may detect a sensing material through a change in resistance of a nano channel using an electric field effect by a gate. In this case, a capacitor structure that gives an electric field effect to the channel 130 may be formed in a double upper and lower portions of the nanochannel.

In the field effect transistor sensor according to an embodiment, the first gate oxide 120 may be made thicker than the second gate oxide 140.

For example, the first gate oxide 120 positioned on the substrate gate 110 may be manufactured to have a thickness of about 100 nm or more using a buried oxide (BOX). According to an embodiment, the first gate oxide 120 may preferably be made of about 145 nm. According to an embodiment, the second gate oxide 140 may be manufactured as thin as 20 nm.

In the field effect transistor sensor according to the embodiment, the length of the substrate gate 110 may be longer than the length of the channel 130 and the length of the upper gate 150 may be shorter than the length of the channel 130. . For example, the length of the channel 130 may be 6 μm, and the length of the upper gate 150 may be 4 μm.

If the length of the upper gate 150 is shorter than the length of the channel 130 corresponding to the distance between the source 160 and the drain 170, even if a voltage is applied to the upper gate 150, the entire channel is caused by an electric field effect. It will not turn on. Accordingly, even when the voltage of the upper gate 150 changes, current may not flow through the channel.

The conductivity of the channel 130 can be adjusted by appropriately applying voltages of the substrate gate 110 and the upper gate 150.

In the field effect transistor sensor according to an embodiment, the substrate gate may operate as a sensing gate for detecting ions or gases.

According to an embodiment, the field effect may be applied to the entire field effect transistor channel 130 by using the substrate gate 110 as a sensing gate. When the substrate gate 110 is used as a sensing gate, since the first gate oxide 120 has a thick thickness, it is stable even if a large amount of charge is adsorbed. Therefore, there is an effect of having a high dielectric breakdown voltage characteristic.

According to an embodiment, the size of the substrate gate 110 becomes the entire size of the semiconductor substrate of the sensor, and the thickness of the first gate oxide 120 is thick and thus has high dielectric breakdown characteristics, and thus can be used as a sensing gate. When the substrate gate 110 is used as a sensing gate, the electrode of the substrate gate 110 must not be connected to any of the circuits to be connected to measure the resistance change of the channel 130 while detecting the detection target. Must be in a state.

Since the second gate oxide 140 on the side of the upper gate 150 has a relatively thin gate oxide thickness characteristic, it reacts sensitively to a small voltage change, so it is possible to increase the sensing sensitivity, but it can be easily damaged by adsorption. have. Also, since the area of the upper gate 150 is relatively small, the ion detection operation area is small, and thus an additional structure in which the electrode area is increased is required to increase the sensitivity.

In the field effect transistor sensor according to an embodiment, the upper gate 150 may operate as a sensitivity control gate for adjusting the detection sensitivity of ions or gases.

When the electrode of the substrate gate 110 is in a floating state, the channel is switched from an off state to an on state as the target to be detected is adsorbed. In this case, by adjusting the voltage of the upper gate 150, the detection sensitivity may be adjusted.

A field effect transistor sensor that detects negative ions or gas molecules in the air needs a driving algorithm for a sensor for stable operation of a device because the gate oxide may be insulated and destroyed when the concentration of the object to be detected is too high.

In the field effect transistor sensor according to an exemplary embodiment, in response to a case in which a current of a predetermined value or more flows through the channel 130, the substrate gate 110 may be grounded or may be initialized by connecting a specific voltage V _bg .

In the field effect transistor sensor according to an embodiment, the substrate gate 110 may further include a conductor packaging (not shown) or a capacitor structure packaging capable of sensing gas or ions.

Although the size of the substrate gate 110 is a basic size of the sensor element, it can be configured to have a larger area in order to increase the detection sensitivity because the electrode size can be further expanded when the sensor is packaged. For example, when a conductor packaging such as TO-5 is connected to the substrate gate 110, the external area of the packaging can be used as a sensing electrode of the sensor.

2 is a configuration diagram illustrating a more specific configuration of a field effect transistor sensor according to an embodiment of the present invention.

Referring to FIG. 2, a field effect transistor sensor according to an embodiment includes a substrate gate 110, a substrate gate electrode 111, a first gate oxide 120 and 121 positioned above the substrate gate 110, and the A field effect transistor (FET) channel 130 positioned above the first gate oxide 120, a second gate oxide 140 positioned above the channel 130, and a second gate oxide 140 positioned above the second gate oxide 140 Passivation for protecting the source 160 and drain 170 electrodes connected through the upper gate 150, the channel 130, the source 160, the drain 170, and the substrate gate electrode 111; 180, 181, 182, 183, 184) may be included. Here, the electrode voltage of the upper gate 150 is V _g , the voltage of the substrate gate electrode 111 is V _bg , the electrode voltage of the source 160 is V _s , and the electrode voltage of the drain 170 is V _ds . have.

FIG. 3 is a diagram illustrating a view of the field effect transistor sensor of FIG. 2 viewed from above.

Referring to FIG. 3, a field effect transistor sensor according to an embodiment may include a substrate 310, an FET channel 320, an upper gate 330, a source 340, and a drain 350. Here, it is _assumed that the gate electrode voltage of the substrate 310 is V _bg and the electrode voltage of the upper gate 330 is V _g .

In this case, the length of the substrate 310 may be longer than the length of the channel 320, and the length of the upper gate 330 may be shorter than the length of the channel 320.

4 is a view for explaining the I-V characteristic of the field effect transistor sensor according to an embodiment of the present invention.

Referring to FIG. 4A, linear axis IV characteristics of a field effect transistor having a channel having an ambipolar characteristic can be confirmed. According to an embodiment, when a detection target is adsorbed on a substrate gate, current flows through the channel due to the electric field effect. For example, when V _bg falls below -20 V or exceeds 20 V, it can be seen that current (I _ds ) flows through the channel. Referring to FIG. 4B, a log-axis IV characteristic of a field effect transistor having a channel having an ambipolar characteristic can be confirmed.

5 is a view for explaining I-V characteristics according to an upper gate voltage in a field effect transistor sensor according to an embodiment of the present invention.

Referring to FIG. 5, a graph obtained by measuring a channel current according to a change in a voltage of an upper gate can be seen. Here, the X-axis means the voltage of the gate electrode of the upper gate. According to an embodiment, when the amount of anions measured at the substrate gate is small (510), when the amount of anions is medium (520), and when the amount of anions is large (530), the threshold voltage value and the current of the channel Values may vary.

In the field effect transistor sensor according to an embodiment, a substrate gate may be floated and negative ions may be adsorbed. In this case, the IV characteristics obtained by varying the amount of charge on the substrate gate and sweeping the upper gate voltage can be checked. As the amount of negative ions adsorbed on the substrate gate increases, the threshold voltage of the upper gate decreases, shifting from negative potential to positive voltage, and the channel current rapidly increases. Therefore, as the upper gate voltage is adjusted to -10 V, -5 V, 0 V, 5 V, and 10 V, the current of the channel varies despite the same amount of substrate gate charge, so that the measurement sensitivity can be adjusted. For example, when 10 V is applied to the upper gate, current (I _ds ) can flow through the channel only when there is a lot of anion adsorption on the substrate gate, but when the upper gate voltage is -10 V, a small positive anion Even with adsorption alone, the current flowing through the channel (I _ds ) is large. That is, detection sensitivity can be adjusted by adjusting the voltage of the upper gate.

6 is a diagram illustrating an operation of a switch in a field effect transistor sensor according to an exemplary embodiment of the present invention.

6, a field effect transistor sensor according to an embodiment includes a substrate 610, an FET channel 620, an upper gate 630, a source 640, a drain 650, and a switch 660. I can. Here, it is assumed that the gate electrode voltage of the substrate 610 is V _bg and the electrode voltage of the upper gate 630 is V _g .

The switch 660 of the field effect transistor sensor according to an embodiment is connected to the gate of the substrate 610 and may change the substrate gate to one of a floating state, a state for self-diagnosis, and an initialization state.

In the field effect transistor sensor according to an embodiment, the switch 660 may cause the substrate gate to be in a floating state. In this case, when anions or gas molecules are adsorbed in the floating substrate gate, an electric field effect may be applied to the channel to allow current to flow.

According to an embodiment, a voltage suitable for the detection condition may be applied to each electrode of the field effect transistor sensor. For example, the drain electrode (V _ds ) is 1 V, the upper gate electrode (V _g ) is 5 V, the source electrode is grounded, and a voltage such as -10 V can be applied to the substrate gate electrode (V _bg ). .

According to an embodiment, in the ion detection mode in which the substrate gate is in a floating state, the substrate gate electrode V _bg may be separated from the circuit and floated. At this time, the polarity and quantity of ions may be determined by an increase or decrease in the current I _ds flowing through the channel.

In the field effect transistor sensor according to an embodiment, the switch 660 may be initialized by grounding the gate of the substrate 610 or connecting a predetermined voltage in response to a case where a current of more than a predetermined value flows through the channel 620. have.

In the field effect transistor sensor according to an embodiment, the switch 660 may switch the substrate gate to a state for self-diagnosis.

Self-diagnosis to check whether the field-effect transistor operates normally can be confirmed by applying a voltage to the substrate gate to confirm whether the IV characteristic appears. If the threshold voltage of a field-effect transistor element having a P-type characteristic is -15 V, sweep the substrate gate voltage to check whether the IV characteristic appears, or apply voltages such as -20 V and -30 V to the substrate gate (V _bg ). You can check whether it is turned on by walking.

According to an embodiment, voltages such as 0 V, -20 V, and -30 V are applied to the substrate gate (V _bg ) of the field effect transistor sensor, and it is checked whether the current flowing through the channel (I _ds ) is an appropriate current. I can. At this time, when the gate oxide is shorted due to dielectric breakdown, too much current may flow through the channel. In addition, when the channel is physically disconnected, the current I _ds may not flow through the channel despite the substrate gate voltage V _bg greater than the threshold voltage.

In the field effect transistor sensor according to an exemplary embodiment, when a current I _ds equal to or greater than a predetermined reference value flows through a channel, a predetermined voltage may be applied to the floating substrate gate electrode to initialize it.

In order to initialize the field effect transistor sensor according to an exemplary embodiment, it is necessary to connect a circuit to a substrate gate in a floating state to remove charges accumulated on the substrate gate to the outside. To this end, the substrate gate may be connected to a circuit by a switch and controlled in a floating state and a state in which a ground or substrate gate voltage is applied.

In the field effect transistor sensor according to an embodiment, when detecting ions, the switch 660 switches the gate of the substrate 610 to a floating state, initiates initialization, or collects charged ions to protect the device. If it is to be removed, the gate of the substrate 610 may be connected to the circuit.

7 is a diagram illustrating an initialization operation of a substrate gate in a field effect transistor sensor according to an embodiment of the present invention.

Referring to FIG. 7, the X-axis represents time and the Y-axis represents the current value of the channel. Accordingly, it is possible to know the change in the current value of the channel over time through the graph of FIG. 7.

When an excessive current flows through a channel of the field effect transistor sensor according to an exemplary embodiment, the sensor may be initialized by connecting a floating substrate gate electrode to a specific voltage. In this case, when a predetermined voltage is applied to the substrate gate in 500 seconds using the switch 660, it can be confirmed that the channel current is initialized.

8 is a graph illustrating a reaction operation for negative ions after applying a constant voltage to an upper gate in the field effect transistor sensor according to an embodiment of the present invention.

Referring to FIG. 8, it can be seen that initialization is performed by connecting a voltage of -15 V to the substrate gate in the vicinity of 300 seconds, 500 seconds, and 800 seconds. According to an embodiment, -15 V may be applied to the upper gate of the field effect transistor sensor, and -15 V may be applied to the substrate gate when the channel current I _ds exceeds a predetermined reference.

9 is a diagram for explaining packaging of a field effect transistor sensor according to an embodiment of the present invention.

9, the packaged field effect transistor sensor includes a sensor chip 910, a substrate gate electrode connection pin 920, an upper gate electrode connection pin 930, a source electrode connection pin 940, and a drain electrode connection pin ( 950).

In this case, the sensor chip 910 is electrically connected to each electrode pad and an external electrode pin, respectively, and the substrate gate electrode 920 may be additionally connected to an electrode of a wide size to increase the sensing area. According to an embodiment, the rear surface of the sensor chip 910 is a substrate gate, and may be packaged by being connected in a form in direct contact with a conductor surface. For example, the outside of the TO-5 packaging connected to the substrate gate may act as a sensing unit of the sensor.

10 is a diagram illustrating a gas detection sensor using a field effect transistor sensor according to an embodiment of the present invention.

Referring to FIG. 10, the field effect transistor gas detection sensor according to an embodiment includes a substrate gate 1010, a substrate gate electrode 1011, and first gate oxides 1020 and 1021 positioned above the substrate gate 1010. , A field effect transistor (FET) channel 1030 positioned above the first gate oxide 1020, a second gate oxide 1040 positioned above the channel 1030, and an upper portion of the second gate oxide 1040 A passivation for protecting the source 1060 and drain 1070 electrodes connected through the upper gate 1050, the channel 1030, the source 1060, the drain 1070, and the substrate gate electrode 1011 ( Passivation: 1080, 1081, 1082, 1083, 1084, a gas sensing layer 1090 positioned under the substrate gate 1010, spacers 1091, 1092, and packaging 1093. Here, the electrode voltage of the upper gate 1050 is V _g , the voltage of the substrate gate electrode 1011 is V _bg , the electrode voltage of the source 1060 is V _s , and the electrode voltage of the drain 1070 is V _ds . have.

According to an embodiment, the gas detection sensor may manufacture a capacitor structure by floating the substrate gate 1010 and connecting the packaging 1093 composed of a conductor. In this case, the spacers 1091 and 1092 may form a space through which gas molecules can be introduced between the gas sensing layer 1090 under the substrate gate and the packaging 1093.

According to an embodiment, the gas detection sensor connects the substrate gate 1010 to an external flat conductor electrode to float, and configures another flat conductor electrode to fabricate a capacitor structure. That is, a gas detection sensor can be manufactured by connecting to a capacitor-type sensor structure made of a flat electrode larger than the size of the substrate of the sensor chip. In this case, the spacers 1091 and 1092 may form a space through which gas molecules can be introduced between the two planar conductor electrodes, and a gas sensing film may be additionally formed on one or both sides of the flat electrode.

According to an embodiment, the space between the gas sensing membrane 1090 and the packaging 1093 may be filled with a porous polymer such as a hydrogel, and a ligand such as a peptide serving as a receptor for a specific gas is fixed to the hydrogel or a gas Nanoparticles, which are molecular adsorption materials, can be mixed and used.

When gas molecules are introduced, they are adsorbed to the gas sensing layer, and the capacitor values due to the gas sensing layer 1090 and the packaging 1093 may change, resulting in an electric field effect. Accordingly, the gas detection sensor according to an exemplary embodiment may detect the target gas through a change in the current I _ds value of the channel.

In the field effect transistor gas detection sensor according to an embodiment, the upper gate may operate as a sensitivity control gate for adjusting the detection sensitivity of the gas.

In the field effect transistor gas detection sensor according to an embodiment, the first gate oxide may be made thicker than the second gate oxide.

In the field effect transistor gas detection sensor according to an embodiment, the length of the substrate gate may be longer than the length of the channel, and the length of the upper gate may be shorter than the length of the channel.

The field effect transistor gas detection sensor according to an exemplary embodiment may further include a switch connected to the substrate gate and capable of changing the substrate gate to one of a floating state and a state for self-diagnosis.

In the field effect transistor gas detection sensor according to an embodiment, the switch may be initialized by grounding a substrate gate or connecting a predetermined voltage in response to a case in which a current of a predetermined value or more flows through a channel.

11 is a configuration diagram illustrating a field effect transistor sensor according to a second embodiment of the present invention.

Referring to FIG. 11, the field effect transistor sensor according to the second embodiment includes a substrate gate 1110, a first gate oxide 1120 positioned above the substrate gate 1110, and an upper portion of the first gate oxide 1120. Including a field effect transistor (FET) channel 1130 positioned at, a second gate oxide 1140 positioned above the channel 1130, and an upper gate 1150 positioned above the second gate oxide 1140 can do. Here, the field effect transistor sensor may include a source 1160 and a drain 1170 electrode connected through the channel 1130. Here, the electrode voltage of the upper gate 1150 may be Vg, and the electrode voltage of the substrate gate 1110 may be V _bg .

According to the second embodiment, ions or gas molecules can be detected using a field effect transistor sensor. The nano field effect transistor sensor may detect a sensing material through a change in resistance of a nano channel using an electric field effect by a gate. In this case, the capacitor structure that gives an electric field effect to the channel 1130 may be formed in a double upper and lower portions of the nanochannel.

In the field effect transistor sensor according to the second embodiment, the first gate oxide 1120 may be made thicker than the second gate oxide 1140.

For example, the first gate oxide 1120 positioned on the substrate gate 1110 may be manufactured to have a thickness of about 100 nm or more using buried oxide (BOX). In this case, the first gate oxide 1120 may be preferably made of about 145 nm. The second gate oxide 1140 may be manufactured as thin as about 20 nm.

In the field effect transistor sensor according to the second embodiment, the length of the substrate gate 1110 is longer than the length of the channel 1130, and the length of the upper gate 1150 can be manufactured to be longer than the length of the channel 1130. have. For example, the length of the channel 1130 may be 6 μm, and the length of the upper gate 1150 may be 8 μm.

If the length of the upper gate 1150 is longer than the length of the channel 1130 corresponding to the distance between the source 1160 and the drain 1170, the upper gate 1150 and the substrate gate 1110 are simultaneously used as sensing gates. I can. In this case, when the upper gate 1150 is longer than the length of the channel 1130, the sensitivity of the channel may be improved than when the upper gate 1150 is shorter than the length of the channel 1130.

The conductivity of the channel 1130 may be adjusted by using a change in the voltage V _{bg of the} substrate gate 1110 and the voltage V _g of the upper gate 1150.

In the field effect transistor sensor according to the second embodiment, the substrate gate 1110 and the upper gate 1150 may operate as sensing gates for detecting ions or gases.

According to the second embodiment, the field effect may be applied to the entire field effect transistor channel 1130 by using the substrate gate 1110 and the upper gate 1150 as sensing gates. If both the substrate gate 1110 and the upper gate 1150 are sensing gates, the sensitivity of the channel resistance due to the voltage change of the upper gate 1150 may be improved.

Since the second gate oxide 1140 on the side of the upper gate 1150 has a relatively thin gate oxide thickness characteristic, it reacts sensitively to a small voltage change, so that the sensing sensitivity can be increased, but it can be easily damaged by adsorption. Therefore, it can be utilized when the concentration of the detection target is low.

The apparatus described above may be implemented as a hardware component, a software component, and/or a combination of a hardware component and a software component. For example, the devices and components described in the embodiments include, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable array (FPA), It can be implemented using one or more general purpose computers or special purpose computers, such as a programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications executed on the operating system. In addition, the processing device may access, store, manipulate, process, and generate data in response to the execution of software. For convenience of understanding, although it is sometimes described that one processing device is used, one of ordinary skill in the art, the processing device is a plurality of processing elements and/or a plurality of types of processing elements. It can be seen that it may include. For example, the processing device may include a plurality of processors or one processor and one controller. In addition, other processing configurations are possible, such as a parallel processor.

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the embodiment, or may be known and usable to those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic media such as floptical disks. -A hardware device specially configured to store and execute program instructions such as magneto-optical media, and ROM, RAM, flash memory, and the like. Examples of the program instructions include not only machine language codes such as those produced by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operation of the embodiment, and vice versa.

As described above, although the embodiments have been described by the limited embodiments and drawings, various modifications and variations are possible from the above description by those of ordinary skill in the art. For example, the described techniques are performed in a different order from the described method, and/or components such as a system, structure, device, circuit, etc. described are combined or combined in a form different from the described method, or other components Alternatively, even if substituted or substituted by an equivalent, an appropriate result can be achieved.

Therefore, other implementations, other embodiments, and claims and equivalents fall within the scope of the claims to be described later.

110: substrate gate
120: first gate oxide
130: channel
140: second gate oxide
150: upper gate
160: source
170: drain

Claims (14)

A substrate gate;
A first gate oxide positioned on the substrate gate;
A field effect transistor (FET) channel positioned over the first gate oxide;
A second gate oxide positioned above the channel;
An upper gate positioned on the second gate oxide; And
A field effect transistor sensor comprising a switch connected to the substrate gate and capable of changing the substrate gate to one of a floating state and a state for self-diagnosis. The method of claim 1,
The substrate gate is a field effect transistor sensor, characterized in that operating as a sensing gate for detecting ions. The method of claim 1,
The upper gate is a field effect transistor sensor, characterized in that operating as a sensitivity control gate for adjusting the detection sensitivity of ions. The method of claim 1,
Field effect transistor sensor, characterized in that the first gate oxide is thicker than the second gate oxide. The method of claim 1,
The length of the substrate gate is longer than that of the channel, and the length of the upper gate is shorter than that of the channel. The method of claim 1,
The switch,
In the floating state, a first voltage set as a detection condition is applied to the substrate gate,
In the state for self-diagnosis, a field effect transistor sensor that applies a second voltage set as a turn-on condition to determine whether to turn on or not to the substrate gate. The method of claim 1,
The switch is a field effect transistor sensor, characterized in that in response to a case where a current of a predetermined value or more flows through the channel, grounding the substrate gate or connecting a specific voltage V _bg to initialize. The method of claim 1,
The field effect transistor sensor, wherein the substrate gate further includes a conductor packaging capable of sensing ions. Conductor packaging;
Gas sensing film;
A spacer forming a space between the conductor packaging and the gas sensing layer;
A substrate gate positioned on the gas sensing layer;
A first gate oxide positioned on the substrate gate;
A field effect transistor (FET) channel positioned over the first gate oxide;
A second gate oxide positioned above the channel;
An upper gate positioned on the second gate oxide; And
A field effect transistor gas detection sensor comprising a switch connected to the substrate gate and capable of changing the substrate gate to one of a floating state and a state for self-diagnosis. The method of claim 9,
The upper gate is a field effect transistor gas detection sensor, characterized in that operating as a sensitivity control gate for adjusting the detection sensitivity of the gas. The method of claim 9,
The field effect transistor gas detection sensor, wherein the first gate oxide is thicker than the second gate oxide. The method of claim 9,
The length of the substrate gate is longer than that of the channel, and the length of the upper gate is shorter than that of the channel. The method of claim 9,
The switch,
In the floating state, a first voltage set as a detection condition is applied to the substrate gate,
In the state for self-diagnosis, a field effect transistor gas detection sensor that applies a second voltage set as a turn-on condition to determine whether to turn on or not to the substrate gate. The method of claim 9,
The switch is a field effect transistor gas detection sensor, characterized in that in response to a case in which a current of a predetermined value or more flows through the channel, grounding the substrate gate or connecting a specific voltage V _bg to initialize.

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