JP2019002727A - Transistor for sensor - Google Patents

Abstract

A sensor transistor suitable for miniaturization is provided.
A sensor transistor includes a silicon substrate, a gate insulating film provided on the silicon substrate, and a circuit around the gate insulating film. An interlayer insulating film 34 to be formed, and a sample container 52 provided on the interlayer insulating film 34 and having a partition wall that goes around the gate insulating film 32, and exposed within a range surrounded by the partition wall of the sample container 52. A reference electrode 43E disposed in the interlayer insulating film 34, a reference electrode terminal exposed in the interlayer insulating film 34 and exposed outside the range surrounded by the partition wall of the sample container 52, and a reference A sensor transistor comprising: a reference electrode wiring 43 extending between the electrode 43E and the reference electrode terminal and disposed in the interlayer insulating film 34.
[Selection] Figure 1

Description

  The technology disclosed in this specification relates to a sensor transistor.

  Sensor transistors have been developed that are configured to output an electrical signal based on channel resistance that varies depending on the measurement object. For example, Patent Document 1 discloses a sensor transistor that detects target biomolecules contained in a sample solvent disposed on a gate insulating film. In this sensor transistor, probe biomolecules that specifically bind to target biomolecules are fixed on the surface of the gate insulating film. When the target biomolecule binds to the probe biomolecule, the channel resistance of the sensor transistor changes depending on the charge of the target molecule. In this sensor transistor, target biomolecules can be detected by measuring the change in channel resistance. Patent Document 2 discloses a sensor transistor for measuring the pH of a sample solvent disposed on a gate insulating film. In this sensor transistor, the gate insulating film acts as an ion sensitive film, and the channel resistance of the sensor transistor changes depending on the pH of the sample solvent. In this sensor transistor, the pH of the sample solvent can be measured by measuring the change in the channel resistance.

JP 2007-304089 A JP 2012-202864 A

  In these sensor transistors, in order to fix the sample solvent at the reference potential, the reference electrode fixed at the reference potential is placed in contact with the sample solvent. The reference electrode is placed so as to come into contact with the sample solvent, for example, in a state of being supported by a support base. However, in order to advance the miniaturization of the sensor transistor, it is necessary to miniaturize the reference electrode and the support base. However, it is difficult to accurately install the reference electrode and the support base. The present specification provides a sensor transistor suitable for miniaturization.

  The sensor transistor disclosed in this specification is used in various applications, and the application is not particularly limited. For example, the sensor transistor can be used for the purpose of observing the state of cell activity in the sample solvent. The sensor transistor can be used for the purpose of detecting the target biomolecule in the sample solvent by fixing the probe biomolecule on the gate insulating film. The sensor transistor can include a semiconductor substrate, a gate insulating film, an interlayer insulating film, a sample container, a reference electrode, a reference electrode terminal, and a reference electrode wiring. The gate insulating film is provided on the semiconductor substrate. The interlayer insulating film is provided on the semiconductor substrate and goes around the periphery of the gate insulating film. The sample container is provided on the interlayer insulating film and has a partition wall that goes around the gate insulating film. The reference electrode is exposed in a range surrounded by the partition wall of the sample container, and is disposed on the interlayer insulating film. The reference electrode terminal is exposed outside the range surrounded by the partition walls of the sample container, and is disposed on the interlayer insulating film. The reference electrode wiring extends between the reference electrode and the reference electrode terminal, and is disposed on the interlayer insulating film. The reference electrode wiring may be disposed through the interlayer insulating film, or may be disposed on the surface of the interlayer insulating film. In this sensor transistor, a reference electrode, a reference electrode terminal, and a reference electrode wiring are disposed in an interlayer insulating film. The reference electrode, the reference electrode terminal, and the reference electrode wiring can be disposed in the interlayer insulating film using a semiconductor manufacturing technique. Thus, it can be evaluated that the sensor transistor has a structure suitable for miniaturization.

FIG. 4 is a schematic cross-sectional view of a main part of a sensor transistor, and is a cross-sectional view of the main part corresponding to the line II in FIG. 3. FIG. 4 is a schematic cross-sectional view of the main part of the sensor transistor, corresponding to the II-II line in FIG. 3. The top view of the transistor for sensors is typically shown.

  1 to 3 show a sensor transistor 10 for observing the state of cell activity. The sensor transistor 10 includes a silicon substrate 20, a gate insulating film 32, an interlayer insulating film 34, various electrodes 43E, 44E, 46E, 48E, various electrode wirings 43, 44, 46, 48, various electrode terminals 43T, 44T, 46T, 48T and a sample container 52 are provided.

As shown in FIG. 1, the silicon substrate 20 includes a p-type drift region 22, an n ⁺ -type source region 24, an n ⁺ -type drain region 26 and a p ⁺ -type base region 28. The source region 24, the drain region 26, and the base region 28 are provided in the surface layer portion of the silicon substrate 20 and are arranged apart from each other. The source region 24 and the drain region 26 are arranged in an adjacent positional relationship, and a part of the drift region 22 is arranged between them. A part of the drift region 22 disposed between the source region 24 and the drain region 26 is particularly referred to as a channel region CH.

  The source region 24 is in contact with the source electrode 44E, and the source electrode 44E is connected to the source electrode wiring 44. As shown in FIG. 3, the source electrode wiring 44 is disposed through the interlayer insulating film 34, and extends between the source electrode 44E and the source electrode terminal 44T to electrically connect the two. It is configured. Similarly, the drain region 26 is in contact with the drain electrode 46 </ b> E, and the drain electrode 46 </ b> E is connected to the drain electrode wiring 46. The drain electrode wiring 46 is disposed through the interlayer insulating film 34, and is configured to extend between the drain electrode 46E and the drain electrode terminal 46T to electrically connect them. The base region 28 is also in contact with the base electrode 48E, and the base electrode 48E is connected to the base electrode wiring 48. The base electrode wiring 48 is disposed through the interlayer insulating film 34, and is configured to extend between the base electrode 48E and the base electrode terminal 48T to electrically connect both.

  2, the reference electrode wiring 43 has one end connected to the reference electrode 43E and the other end connected to the reference electrode terminal 43T. The reference electrode 43 </ b> E is exposed in a range surrounded by the partition wall of the sample container 52 and is in contact with the culture solution 54, and is disposed on the surface of the interlayer insulating film 34. The reference electrode terminal 43T is exposed outside the range surrounded by the partition wall of the sample container 52, and is disposed on the surface of the interlayer insulating film. The reference electrode wiring 43 is disposed through the interlayer insulating film 34, and is configured to extend between the reference electrode 43E and the reference electrode terminal 43T to electrically connect both. Instead of this example, the reference electrode wiring 43 may be provided on the surface of the interlayer insulating film 34 so as to pass between the interlayer insulating film 34 and the partition walls of the sample container 52. The material of the reference electrode 43E is a chemically stable inert material, for example, silver or platinum.

  As shown in FIG. 1, the gate insulating film 32 covers a part on the surface of the silicon substrate 20, is disposed between the source region 24 and the drain region 26, and is in contact with the channel region CH. ing. The thickness of the gate insulating film 32 is, for example, 5 to 50 nm. The material of the gate insulating film 32 is, for example, a silicon oxide film or a silicon nitride film. As described above, an n-type channel MOSFET is formed on the silicon substrate 20.

  As shown in FIGS. 1 and 3, the interlayer insulating film 34 is provided on the surface of the silicon substrate 20 and is configured to make a round around the gate insulating film 32. In other words, an opening is formed in a part of the interlayer insulating film 34, and the gate insulating film 32 is provided in the opening. As described above, the interlayer insulating film 34 is provided with various electrodes, various electrode wirings, and various electrode terminals.

  As shown in FIGS. 1 and 3, the sample container 52 has a partition wall provided on the interlayer insulating film 34 so as to make a round around the gate insulating film 32. The partition wall of the sample container 52 has a cylindrical shape. One end of the sample container 52 is fixed to the surface of the interlayer insulating film 34, and defines a space for retaining the dropped culture solution 54.

  In the sensor transistor 10, cells are adhered to the surface 32 a of the gate insulating film 32. When a cell adhering to the surface 32a of the gate insulating film 32 is activated by receiving a specific stimulus, the ion channel of the biological membrane of the cell is opened and ions contained in the culture solution 54 flow into the cell, The membrane potential changes. As a result, the channel resistance of the channel region CH changes. In the sensor transistor 10, this change in channel resistance is measured as a change in output voltage. In this way, the sensor transistor 10 can observe the state of cell activity.

  The sensor transistor 10 is characterized in that a reference electrode 43E, a reference electrode wiring 43, and a reference electrode terminal 43T are disposed in an interlayer insulating film 34. The reference electrode 43E, the reference electrode wiring 43, and the reference electrode terminal 43T can be formed by patterning the interlayer insulating film 34 using a semiconductor manufacturing technique. As described in the background art, a conventional sensor transistor is installed such that a rod-like reference electrode supported by a support base is in contact with a sample solvent. Compared with such a conventional sensor transistor, it can be evaluated that the sensor transistor 10 has a structure suitable for miniaturization.

  In addition, the conventional sensor transistor has a problem that the position of the reference electrode is not stable, and thus the potential of the culture solution is not stable, and output variation increases. On the other hand, in the sensor transistor 10, the position of the reference electrode 43E in the sample container 52 is fixed. Thereby, in the sensor transistor 10, the potential of the culture solution 54 is stabilized, and variations in output are suppressed.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

10: sensor transistor, 20: silicon substrate, 22: drift region, 24: source region, 26: drain region, 28: base region, 32: gate insulating film, 34: interlayer insulating film, 43: reference electrode wiring, 43E : Reference electrode, 43T: reference electrode terminal, 44: source electrode wiring, 44E: source electrode, 44T: source electrode terminal, 46: drain electrode wiring, 46E: drain electrode, 46T: drain electrode terminal, 48: base electrode wiring, 48E: Base electrode, 48T: Base electrode terminal, 52: Sample container, 54: Culture solution

Claims (2)

A sensor transistor,
A semiconductor substrate;
A gate insulating film provided on the semiconductor substrate;
An interlayer insulating film provided on the semiconductor substrate and circulating around the gate insulating film;
A sample container provided on the interlayer insulating film and having a partition wall that goes around the gate insulating film;
A reference electrode that is exposed in a range surrounded by the partition wall of the sample container and is disposed in the interlayer insulating film;
A reference electrode terminal that is exposed outside the range surrounded by the partition wall of the sample container and is disposed in the interlayer insulating film;
A sensor transistor comprising: a reference electrode wiring extending between the reference electrode and the reference electrode terminal and disposed in the interlayer insulating film.   The sensor transistor according to claim 1, wherein the reference electrode wiring is disposed through the interlayer insulating film.

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